Kind: captions
Language: en
the following is a conversation with
peter white a theoretical physicist at
columbia outspoken critical string
theory and the author of the popular
physics and mathematics blog called not
even wrong
this is the lex friedman podcast to
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in the description and now here's my
conversation with peter white
you're both a physicist and a
mathematician
so let me ask what is the difference
between physics and mathematics
well there's kind of a conventional
understanding of the subject that
they're
two you know quite different things so
that mathematics is about you know
making
rigorous statements about
these abstract you know abstract things
things of mathematics and and proving
them rigorously and physics is about you
know doing experiments and
testing various models and that but i
think the more interesting thing is that
the
there's a
yeah there's a wide variety of what
people do as mathematics what they do is
physics and there's a significant
overlap and that i think is actually the
much much very very interesting area and
if you go back kind of far enough to in
in in history and look at figures like
newton or something i mean there it at
that point you can't really tell you
know was newton a physicist or a
mathematician yeah mathematicians will
tell you as a mathematician the
physicist will tell you as a physicist
but he would say he's a philosopher yeah
yeah
that's that's interesting but uh yeah
anyway there there was kind of no such
distinction then it's more of a modern
thing and
but anyway i think these days there's a
very interesting space in between the
two so in the story of the 20th century
and the early 21st century what is the
overlap between mathematics and physics
would you say
well i think
it's actually become very very
complicated i think it's really
interesting to see a lot of what my
colleagues and
math department are doing they
most of what they're doing they're doing
all sorts of different things but um
most of them have some kind of overlap
with physics or other
so i mean i'm personally interested in
one spec one particular aspect of this
overlap which i think
has a lot to do with the most
fundamental ideas about physics and
about
mathematics but um
there's just
you you kind of see this this uh
really really everywhere at this point
which particular overlap are you looking
at group theory yeah so the um
at least
what the way it seems to me that if you
look at physics and look at the our most
successful um
laws of fundamental physics
they're
really you know they have a certain kind
of mathematical structure it's based
upon
certain kind of mathematical objects and
geometry connections and curvature the
spinners the rock equation
and uh that
these this very deep mathematics
provides kind of a unifying
set of meth of ways of thinking that
allow you to to make a unified theory of
physics but the interesting thing is
that if you go to mathematics and look
at what's been going on in mathematics
the last
1500 years and even especially recently
there's a
similarly some kind of unifying ideas
which bring together different areas of
mathematics and which have been
especially powerful in number theory
recently and
there's a book for instance by um
edward frankel about love and math and
oh yeah that book is great i recommend
it highly it's uh partially accessible
but there's a nice audio book
that i had listened to while
running an exceptionally long distance
like across the san francisco
bridge
and uh there's something magic about the
way he writes about it but some of the
group theory in there is a little bit
difficult
uh yeah it's a problem with any of these
things to kind of really say what's
going on is
and make it accessible is very hard
he in this book and elsewhere i think
you know takes the attitude that kinds
of mathematics he's interested in and
that he's talking about are provide kind
of a grand unified theory of mathematics
they um they bring together geometry and
number theory and
representation theory a lot of different
ideas
in a really
unexpected way
but i think to me the most fascinating
thing is if you look at
the kind of grand unified theory of
mathematics he's talking about and you
look at the physicists kind of ideas
about unification it's more or less the
same mathematical objects are appearing
in both
so it's this um i think there's a really
we're seeing a really strong indication
that you know the deepest
ideas that we're discovering about
physics and some of the deepest ideas
that mathematicians are learning about
are really are you know intimately
connected
is there something like if i was five
years old you were trying to explain
this to me is there ways to try to sneak
up to the to to what this unified world
of mathematics looks like you said
number theory he said geometry
words like topology
what does this universe begin to look
like are these what should we imagine in
our mind is it a
a three-dimensional surface
and we're trying to say something about
it
is it uh
triangles and squares and cubes like
what what are we supposed to imagine our
minds is this natural number what what's
a good thing to try to
for people that
don't know any of these tools except
maybe some basic calculus and geometry
from high school that they should keep
in their minds
as to the unified world of mathematics
that also
allows us to explore the unified world
of physics
the i mean what i
find kind of remarkable about this is
the way in which
these we've discovered these ideas but
they're they're actually quite alien to
our everyday understanding you know we
grow up in this three spatial
dimensional world and we have
intimate understanding of certain kinds
of geometry and certain kinds of things
but um these things that we've
discovered in both math and physics are
that they're not at all
close have any obvious connection to
kind of human everyday experience that
they're really quite different and i can
say some of my initial fascination with
this when i was
young and starting to learn about it was
actually
exactly this um
this kind of arcane nature of these
things it was a little bit like being
being told well there are these kind of
some semi-mystical experience that you
can acquire by a long study and whatever
except
that that it was actually true there's
actually evidence that this actually
works
so you know i'm a little bit wary of
trying to give people
and that kind of thing because i think
it's mostly misleading but one thing to
say is that you know that geometry is a
large
part of it and um
maybe one interesting thing to say very
that's about more recent some of the
most recent ideas is that it um when we
think about the geometry of our space
and time it's kind of three spatial and
one
time dimension it's a um
physics is in some sense about
something as kind of four dimensional in
a way and that a really interesting
thing about um some of the recent
developments and number theory have been
to realize that the um
these ideas that we were looking at you
know naturally fit into a context where
your theory is for is kind of four
dimensional
so
so so so i mean geometry is a big part
of this and we know a lot and feel a lot
about you know two one two three
dimensional geometry so wait a minute so
we can at least rely
on the four dimensions of space and time
and say that we can get pretty far by
working that in those four dimensions i
thought you were going to scare me that
we're going to have to go to many many
many many more dimensions than that
my point of view which is which goes
against a lot of these ideas about
unification is that no this is really
everything we do we know about really is
about four dimensions that um
and and that you can actually understand
a lot of these structures that we've
been seeing in fundamental physics and
in
in number theory just in terms of
four dimensions that it's kind of
it's in some sense i would claim
has been a really um
has been kind of a mistake that
physicists have made and
for decades and decades to try to
to try to go to higher dimensions to try
to formulate a theory in higher
dimensions and then then you're stuck
with
the problem how do you get rid of all
these extra dimensions that you've
created and
because we only ever see anything
important
that kind of thing leads us astray you
think so so creating all these extra
dimensions just to get to give yourself
extra degrees of freedom
yeah it's not i mean isn't that the
process of mathematics is to create
all these trajectories for yourself but
eventually you have to end up at the uh
like a final place but it's okay to
it's okay to sort of um
create abstract objects on your path to
uh proving something
yeah so yeah certainly but and from from
mathematicians point of view
i mean
the kinds of mathematicians also are
very different than physicists and that
we like to develop very general theories
we like to if we have an idea we want to
um see what's the greatest generality in
which you can talk about it so from the
point of view of most of the ways
geometry is formulated um
by mathematicians it really doesn't
matter it works in any dimension we can
do
one two three four any any number
there's no particular
for most of geometry there's no
particular special thing but for
but um
and anyway but but what physicists have
have been trying to do over the years is
try to understand
these fundamental theories in a
geometrical way and it's very tempting
to kind of just
start bringing in
extra dimensions
and using them to explain the structure
but
um
typically this this attempt kind of
founders because you just don't know
you end up not being able to explain why
we only see four and anyway
it is nice in the space of physics that
uh like if you look at from o's last
theorem
it's much easier to prove that there's
no solution for n equals three
than it is for the general case
and and so i guess that's the nice
benefit of being a physicist is you
don't have to worry about the general
case because we live in a universe with
n equals
four in this case
yeah the physiophysicists are very
interested in
saying something about specific examples
and
i find that interesting even when i'm
trying to do things in mathematics and
i'm trying even teaching courses and
mathematics students i find that
i'm teaching them in a different way
than um most mathematicians because i'm
very often very focused on examples on
what's
what's kind of the crucial example that
shows how this um
this powerful new mathematical technique
how it works and why you would want to
to do it
and i'm less interested in kind of
you know proving a precise theorem about
exactly when it's going to work and when
it's not going to work do you think
about really simple examples like uh
both for teaching and when you
try to solve a difficult problem are you
do construct like the simplest possible
examples that captures the fundamentals
of the problem and try to solve it yeah
yeah exactly that's often
a really fruitful way to if you've got
some idea to you just kind of try to
boil it down to what's the simplest
situation in which this kind of thing is
going to happen and then try to really
understand that and understand that and
that that is almost always a really good
way to get insight into do you work with
uh paper and pen or like for example for
me
coming from the programming side if you
if i look at a model if i look at some
kind of mathematical object
i like to mess around with it sort of
numerically i just visualize different
parts of it visualize however i can so
most of the work is like with neural
networks for example as you try to play
with the simplest possible example and
just to build up intuition by
um you know
any kind of object has a bunch of
variables in it
you start to mess around with them in
different ways and visualize in
different ways to start to build
intuition
or do you go to einstein route and just
imagine
like
everything inside your mind and sort of
build like thought experiments and then
work purely on paper and pen
well the problem with this kind of
stuff
i'm interested in is it you you rarely
can kind of
it's really something that is really
kind of
or even the simplest example
you know it can is you can kind of see
what's going on by it looking at
something happening in three dimensions
there's there's generally this the
structures involved are um
either they're more abstract or if you
try to kind of embed them in some kind
of space and where you could um
manipulate them in some kind of
geometrical way it's going to be a much
higher dimensional space so even simple
examples
the embedding them into
three-dimensional space you're losing a
lot yeah or but to capture what your
what you're trying to understand about
them you have to go to four or more
dimensions so it starts to get to be
hard to
i mean you can
train yourself to try it as much as to
kind of
think about things in your mind and you
know i often use pad and paper and often
if i'm
in my office often use the blackboard
um and you are kind of drawing things
but they're really kind of more abstract
representations of how
things are supposed to fit together and
they're not really
unfortunately not just kind of really
living in three dimensions where you can
are we supposed to be sad or excited by
the fact that our human minds can't
fully comprehend the kind of mathematics
you're talking about i i mean
what do we make of that i mean to me
that makes me quite sad it makes me it
makes it seem like there's a giant
mystery out there that we'll never truly
get to experience
directly it is kind of sad you know how
difficult this is i mean or i would put
it a different way that um
you know most questions that people have
about this kind of thing
you know you couldn't you can give them
a really a true answer and really
understand it but
the problem is is one more of um of time
it's like
yes you know i could explain to you how
this works but you have to be willing to
sit down with me and you know work at
this repeatedly for
you know for hours and days and weeks
and you you mean it's just going to take
that long for your mind to really wrap
itself around what's going on and um
and that so that does make things an
inaccessible which is uh
which is sad but it again i mean it's
just kind of part of life that we all
have a limited amount of time and we
have to decide what we're going to
what we're going to spend our time doing
speaking of a limited amount of time we
only have a few hours maybe a few days
together here on this podcast
let me ask you the question
of um
amongst many of the ideas that you work
on
in mathematics and physics what to use
the most beautiful idea or one of the
most beautiful ideas maybe a surprising
idea and once again unfortunately the
way life works we only have a limited
time together try to convey such an idea
okay well actually let me just tell you
something which i i'm tempted to kind of
start trying to explain what i think is
this most powerful idea that brings
together math and physics ideas about
groups and representations and how it
fits quantum mechanics and but in some
sense i wrote a whole textbook about
that and
i don't think we really have time to get
very far into it so well can i actually
on a small tangent you did write a paper
towards the grant unified theory
mathematics and physics
um maybe you could step there first what
is the key idea in that paper well i
think we've kind of gone over that i
think that the key idea is what we were
talking about earlier that um
that just kind of a claim that if you
look and see what's that have been
successful ideas in unification in
physics and over the last
um 50 years or so and what
has been happening in mathematics and
the kind of thing that
frankl's book is about that these are
very much the same kind of mathematics
and so it's kind of an argument that
there really
is
you shouldn't be looking to unify just
math or just
fundamental physics but taking
inspiration for looking for new ideas in
fundamental physics that they are going
to be in the same direction of
getting deeper into mathematics and
looking for more inspiration mathematics
from
these successful ideas about fundamental
physics
could you put words to sort of the
disciplines we're trying to unify so you
said number theory are we literally
talking about all the major fields of
mathematics so it's like the number
theory geometry
uh so the differential geometry topology
like yeah
so the i mean one one name for this
that this is acquired in in mathematics
is the so-called language program
and uh so this started out in
mathematics it's that
you know robert langland's kind of
realized that a lot of what people were
doing and um
that was starting to be really
successful in number theory in the
60s and so that this actually
was
anyway that this could be could be
thought of in terms of um
these ideas about symmetry in groups and
representations
and and
in a way that was also close to some
ideas about about geometry and um then
it more later on in the 80s and 90s
there was something called um
geometric language that people realize
that you could take what people have
been doing in number theory in language
and and and get re just forget about the
number theory and ask what is this
telling you about geometry and you get a
whole some new insights into certain
kinds of geometry that way
so it's anyway that that's kind of the
name for this area is langlins and
geometric language
and just recently in the last few months
there's been um
there's kind of a really major paper
that uh appeared by uh peter schultz and
laurel farg where they
you know made you know some serious
advance and trying to understand
a very much
kind of a local problem of what happens
in number theory near a certain prime
number and they
turn this into a problem of exactly the
the kind the geometric
language people had been doing these
kind of pure a pure geometry problem and
they
found
by generalizing the mathematics they
could actually reformulate it in that
way and it worked perfectly well
one of the things that makes me sad
is you know i'm um pretty knowledgeable
person and then
uh what is it at least i'm in the
neighborhood of like theoretical
computer science right
and it's still way out of my reach and
so many people talk about like language
for example is one of the most brilliant
people in mathematics and just really
admires work
and i can't
it's like almost i can't hear the music
that he composed and it makes me sad
yeah well i mean i i think that
unfortunately it's not just
you as i think even most mathematicians
have no really don't actually understand
this about them in the the group of
people who really understand
all these ideas and so for instance this
paper of
schultz and farg that i was talking
about the number of people who really
actually understand how that works is
anyway one
very very small and so it's uh so i i
think even
you find if you talk to mathematicians
and physicists even they will often feel
that you know there's this really
interesting sounding stuff going on and
which i should be able to understand
it's kind of in my own field i have a
phd in but it still seems it's pretty
clearly far beyond me right now
well if we can step into the back to the
question of beauty uh
is there an idea that maybe is a little
bit smaller
that you find beautiful in the space of
mathematics or physics
there's an idea that you know i kind of
went got a physics phd and spent a lot
of time learning about mathematics and i
guess
it was embarrassing and i hadn't really
actually understood this very simple
idea
um until and kind of learned it when i
actually started teaching math classes
which
is maybe that there there may be
there's a simple way to explain kind of
the fundamental way in which algebra and
geometry are connected so you normally
think of geometry is about these spaces
and these points and
and you think of algebra is this very
abstract thing about with these
abstract objects that satisfy certain
kinds of relations you can multiply them
and add them and
do stuff but it's it's completely
abstract and there's nothing geometric
about it but the um
the kind of really
fundamental idea is that unifies algebra
and geometry is to is to realize is to
think when whenever anybody gives you
what you call an algebra some abstract
thing of things that you can multiply
and add
that you should ask yourself
is that algebra the space of functions
on some geometry
so one of the most surprising examples
of this for instance is a
i mean a standard kind of
thing that seems to have nothing to do
with geometry is the um
is the
the integers so then they're you can you
can multiply them and add them it's
it's an algebra but the um
it has seems to have nothing to do with
geometry but what you can it turns out
but if you ask yourself this question
and ask you know is are integers can you
think if somebody gives you an integer
can you think of it as a function on
some space
on some geometry and it turns out that
yes you can and the space is the space
of prime numbers
and so what you do is you just if
somebody gives you an integer
you can make a function on the prime
numbers by just
you know at each prime number taking
that
that integer modulo that prime so if uh
if you say i don't know if you get given
you know 10 and you ask what is its
value at 2 well it's
it's 5 times 2 so mod 2 it's zero so it
has zero one what what is what is this
value at three
well it's nine plus one so it's it's one
mod three
so it's about it's zero at two it's one
at three and you can kind of keep going
and so
this is really kind of a
truly fundamental idea it's at the basis
of what's called algebraic geometry and
it just links these two parts of
mathematics that look completely
different and it's just an incredibly
powerful idea and so much of mathematics
emerges from this kind of
simple relation so uh you're talking
about mapping from one discrete space to
another to another so
um
for a second i thought perhaps
uh mapping like a continuous space of
discrete space like functions over a
continuous space
because yeah well you can i mean you can
take if somebody gives you a space
you can ask you can say well let's let's
and this is also this is part of the
same idea the part of the same idea is
that if you try and do geometry and
somebody tells you here's a space
that what you should do is you said wait
say wait wait a minute maybe i should be
trying to solve this using algebra and
so if i do that the way to start is you
give me the space
i start to think about the functions of
the space okay so for to each point in
the space i associate
a number i can take different kinds of
functions and different kinds of values
but but basically functions on a space
so
what this
insight is telling you is that if you're
a geometer often the way to to to work
is to trans change your problem into
algebra by changing your space stop
thinking about your space and the points
in it and think about the functions on
it got it and if you're if you're an
algebraic and you and you've got these
abstract algebraic gadgets that you're
multiplying and adding say wait a minute
are those gadgets
can i think of them in some way as a
function on a space what would that
space be and what kind of functions
would they be and that going back and
forth really brings these two
completely different looking areas of
mathematics together do you have uh
particular examples where it allowed to
prove some difficult things by jumping
from one to the other is that something
that's a part of modern mathematics
where such jumps are made oh yes this is
kind of all the time
a lot much much of modern number theory
is kind of based on this idea but
and and when you start doing this you
start to realize that you need you know
what simple
things simple things on one side
algebras start to require you to think
about
the other side about geometry in a new
way you have to kind of get a more
sophisticated idea about geometry or if
you
start thinking about the functions on a
space
you may have you may need a more
sophisticated kind of algebra but um but
in some sense i mean much or most of
modern number theory is
based upon this move to geometry and um
there's also a lot of geometry and
topology is also based upon
yeah changing if you want to understand
the topology of something you look at
the functions you do dram comology and
you get the topology
anyway
well let me let me ask you then the
ridiculous question you said that this
idea is beautiful
uh can you formalize the definition of
the word beautiful
and why is this beautiful like first why
is this beautiful and second
um what is beautiful
well
and i think there are many different
things you can find beautiful for
different reasons i mean i think in this
context
the notion of beauty i think really is
just kind of
an idea is beautiful if it's
packages a huge amount of kind of
power and information into
something very simple so in some sense
you i mean
you can almost kind of try and measure
it in the sense of you know what's the
what are the implications of this idea
what
non-trivial things does it tell you
versus
you know how how how how simply can you
can you express the idea and so so level
of compression yeah uh what is it
correlates with uh beauty yeah that's
that's one and one aspect of it and so
you can start to tell that an idea is
becoming uglier and uglier
as you start kind of having to
you know it doesn't quite do what you
want so you throw in
something else to the idea and you keep
doing that until
you get what you want but that's how you
know you're doing something uglier and
uglier when you have to kind of keep
adding in
more
more into what was originally a fairly
simple idea and making it more and more
complicated to get what you want
okay so let's put some uh philosophical
words on the table and try to make some
sense of them one word is beauty another
one is simplicity as you mentioned
another one is truth
so
do you have a sense if i give you two
theories one is
simpler one is more complicated
do you have a sense which one is more
likely to be true
to uh
capture
deeply
the fabric of reality
the simple one or the more complicated
one yeah i think all of our evidence
what we see in the history of the
subject is the the simpler one though
often it's a surprise it's simpler in a
surprising way but um
yeah that that we just don't we just
anyway when the kind of best theories
have been coming coming up with are
ultimately when properly understood
relatively simple and uh much much
simpler than you would expect them to be
do you have a good explanation why that
is is it just because humans want it to
be that way are we just like ultra
biased then we we we just kind of
convinced ourselves
that simple is better because we find
simplicity beautiful or is there
something about at the our actual
universe
that uh at the core is simple
my own belief is that there is something
about a universe that that's simple and
i was trying to say that you know there
is some some kind of fundamental thing
about math physics
and physics and all this picture which
is um
which which is in some sense simple
it's true that you know it
it's of course true that you know our
minds have certain have
are very limited and can certainly do
certain things and not others so it
it's it's in principle possible that
there's some
great insight there are a lot of
insights into the way the world works
which is aren't accessible to us because
that's not the way our minds work we
don't and that what we're seeing this
kind of simplicity is just because
that's
all we ever have any hope of seeing but
so there's a brilliant
physicist by the name of sabine
hasenfelder who both agrees and
disagrees with you i suppose agrees
that uh
the final answer will be simple yeah
but uh simplicity and beauty leads us
astray in the lo in the local pockets of
scientific progress
uh do you uh do you agree with her
disagreement do you disagree with her
agreement
i agree with the agreement uh well i i i
i i i
yes i thought it was really fascinating
reading your book and and and anyway it
was finding disagreeing with with a lot
but then at the end when she says yes
when we find
there when we actually figure this out
it will it will be simple and yeah and
okay so
we agree in the end
does beauty lead us astray which is the
the core thesis of her work
in that book i actually i guess i do
disagree with her on on that so much i
don't think and especially and i
actually fairly strongly disagree with
her about sometimes sometimes the way
she'll refer to math and
so the problem is
you know
physicists and people in general just
refer to as math and and they're often
um
they're they're often meaning not what i
would call math which is the interesting
ideas of math but just
cause some complicated calculation and
and so um
i i guess
my feeling about it is more that it's
very
the problem with talking about
simplicity and using simplicity as a
guide
is that it's very um
it's very easy to fool yourself and you
know it's very easy to decide
to you know to fall in love with an idea
you have an idea you think oh this is
this is great and you fall in love with
it and it's like any kind of love affair
it's very easy to believe that you know
you're the object of your affections is
much more beautiful than they others
might think and they're that they really
are and that's
very very easy to do so um if you say
i'm just gonna pursue ideas about
beauty and
this and mathematics and this it's
extremely easy to to just fool yourself
i think um and i think that's a lot of
what
the story is she was thinking of about
where people have gone astray that i
think it's i would argue that as more
people it's not that there was some
simple powerful wonderful idea which
they'd found and it turned out not to be
um
not to be useful but it was more that
they kind of fooled themselves that this
was actually a better idea than it
really was and it was
simpler more beautiful than it really
was is a lot of the story um i see so
it's not that the simplicity would be
lisa's astrays that's just people or
people and they
uh fall in love with with whatever idea
they have and then they they weave
narratives around that idea or they
present in such a way that uh emphasizes
uh the simplicity and the beauty
yeah that's part of it but i mean the
thing about physics that you have
is that you you know what what really
can tell
if you can do an experiment and check
and see if nature is really doing what
your your idea expects that you you do
in principle have a way of really of
testing it and and it's certainly true
that if you um
you know if you thought you had a simple
idea and that doesn't work and you got
into an experiment and what actually
does work is somewhere maybe some more
complicated version of it that can
certainly happen and
that that that can be true
i think her emphasis is more that i
don't really disagree with is that
um
people should be concentrating on
when they're trying to develop better
theories on
morons on self-consistency not so much
on beauty but you know not is this idea
beautiful but you know is there
something about the theory which is not
quite consistent
and that and use that as a guide
that there's something wrong there which
needs fixing and and so i think that
part of her argument i think i was
we're on the same page about
uh what's what is consistency in
inconsistencies
what what exactly um
do you have examples in mind
well it can be just simple inconsistency
between theory and an experiment that if
you so we have this
great fundamental theory but there are
some things we see out there which don't
seem to fit in it like like dark energy
and dark matter for instance
but if there's something which you can't
test experimentally i think
you know she would argue and i would
agree that for instance if you're trying
to think about
gravity and how are you going to have a
quantum theory of gravity you should
kind of
be you know and test any of your ideas
with kind of
kind of a thought experiment you know is
does this actually give a consistent
picture what's going to happen of what
happens in this particular situation or
not
so this is a good example you've written
about this um
you know since quantum gravitational
effects are
really small
super small arguably unobservably small
should we have hope to arrive at a
theory of quantum gravity somehow
what are the different ways we can get
there you've mentioned that you're not
as interested in that effort because
basically
yes you cannot
have uh ways to scientifically validate
it given the tools of today yeah i've
actually you know i've over the years
certainly spent a lot of time learning
about
gravity and about attempts to quantize
it but it
it hasn't been that much
in the past the focus of what i've been
thinking about but
i mean my feeling was always you know as
i think speed would agree that the uh
you know one way you can pursue this if
you if you can't do experiments is
just this kind of search for consistency
you know it can be remarkably hard to
come up with a completely consistent
model of model of this in a way that
brings together quantum mechanics and
general relativity
and that's i think kind of been
the traditional way that people who have
pursued quantum gravity have often
pursued you know
we have the best route to finding a
consistent
theory of quantum gravity and string
theorists will tell you this
other other people will tell you it it's
it's kind of what people argue about but
but the problem with all of that is that
you end up
um
the danger is that you end up with that
that everybody could be successful
everybody everybody's
program for how to find a theory of kind
of gravity you know ends up with
something that is consistent
and so
in some sense you could argue this is
what happened to the strength there is
they um
they solved their problem of finding a
consistent theory of quantum gravity and
they ended but they found 10 of the 500
solutions so
you you know
if you believe that everything that they
would like to be true is true well
okay you've got a theory but it's
it ends up being kind of useless because
it's just one of
an infant essentially infinite number of
things which you have no way to
experimentally distinguish and so this
is a
just a depressing situation
um but but i but i do think that there
is a um
so again i think pursuing ideas about
what
more about beauty and how can you
integrate and unify
these issues about gravity with other
things we know about physics and can you
find a theory which were they were these
fit together in a in a way that makes
sense and and hopefully predict
something that's much more promising
well it makes sense and hopefully i mean
we'll sneak up
onto this question a bunch of times
because you kind of said
uh a few slightly contradictory things
which is like it's nice to have a theory
that's consistent
but then
if the theory is consistent it doesn't
necessarily mean anything
so like it's it's not enough it's not
enough it's not enough and that's the
problem so it's like it keeps coming
back to
okay there should be some experimental
validation
so okay
let's talk a little bit about string
theory you've been uh
a bit of an outspoken critic of strength
theory
maybe one question first to ask is what
is string theory
and uh
beyond that why is it
wrong
or rather the title of your blog says
not even wrong okay
well one interesting thing about the
current state of strength theory is that
i think it i'd argue it's actually very
very difficult to at this point to say
what string theory means if people say
they're string theorists what they
mean and what they're doing is uh
it's kind of hard it's hard to pin down
the meaning of the term but the but the
initial meaning i think goes back to um
there was kind of a series of
developments starting in 1984 in which
people felt that they had found a
unified theory of
our so-called standard model of of all
the standard
well-known kind of particle interactions
and gravity and it all fit together in a
quantum theory and that you could do
this
in a very specific way by
instead of thinking about
having a quantum theory of particles
moving around in space time think about
uh quantum theory of kind of
one-dimensional loops moving around in
space-time so-called strings and so
instead of one degree of freedom
these have an infinite number of degrees
of freedom it's a much more complicated
theory but you can imagine
okay we're going to quantize this theory
of loops moving around in space-time
and what they found is that they
is that you could make you could do this
and you could fairly relatively
straightforwardly make sense of
of such a quantum theory but only if
space and time together were
10-dimensional
and so then you had this problem again
the problem i referred to at the
beginning of okay now once you make that
move you've got to get rid of six
dimensions
and so the hope was that
you could get rid of the six dimensions
by making them very small and that
consistency of the theory would require
these that these six dimensions um
satisfy a very specific condition called
being a claudio manifold and that we
knew very very few examples of this
so what got a lot of people very excited
back in
84 85 was the hope that
you could just take this some 10
dimensional string theory and
find one of a limited number of possible
ways of
of getting rid of six dimensions by
making them small and then you would end
up with a an effective four-dimensional
theory which looked like the real world
this was the hope so then
there's been a very long story about
what happened to that hope over the
years i mean
i i would argue and like part of the
point of the book and its title was that
um
you know that this this ultimately was
it was a failure that you ended up that
this idea just didn't um
there ended up being just too many ways
of doing this and you didn't know how to
do this consistently
that it was kind of
not even wrong in the sense that you
couldn't even you never could pin it
down well enough to actually get a real
falsifiable prediction out of it that
would tell you it was wrong but it was
um
it was kind of in the in the realm of
ideas which initially looked good but
the more you look at them
they just um
they don't work out the way the way you
want and they don't actually end up
carrying the power or the that you
originally had this vision of
and yes the the book title is not even
wrong your blog your excellent blog
title is not even wrong
okay but there is nevertheless been a
lot of excitement about string theory
through the decades as you mentioned uh
what are the different flavors of ideas
that came
uh
like they branched out you mentioned 10
dimensions you mentioned
loops with infinite degrees of freedom
what what other interesting ideas to you
that kind of emerge from this world
well yeah i mean the problem in talking
about the whole subject and well partly
one reason i wrote the book
is that you know it it gets very very
complicated i mean there's a huge amount
you know you a lot of people got very
interested in this a lot of people
worked on it and and in some sense i
think what happened is exactly because
the idea didn't really work
that this caused people to
you know instead of focusing on this one
idea and digging in and working on that
they just kind of
kept trying new things and so
people i think ended up wandering around
in a very very rich space of ideas about
mathematics and physics and discovering
you know all sorts of really interesting
things it's just the problem is there
tended to be an inverse relationship
between how interesting and beautiful
and fruitful this new
idea that they were trying to pursue was
and how much it looked like the real
world
so there's a lot of beautiful
mathematics came out of it
i think one of the most spectacular is
what the
physicists call two-dimensional
conformal field theory and so these are
basically
[Music]
quantum field theories and kind of think
of it as one space and one time
dimension which
you know have just this huge amount of
symmetry and a huge amount of structure
which
and just some totally fantastic
mathematics behind it and um and again
and and some of that mathematics
is exactly also what appears in the
language program so a lot of the um
first interaction between math and
physics around the language program has
been around these two-dimensional
conformal field theories
is there um something you could say
about what the major problems are with
strength theory
so
like um
besides
that there's no experimental validation
you've written that a big hole
in string theory has been its
perturbative definition yeah
perhaps that's one can you explain what
that means well maybe to begin with i
mean i think i mean the simplest thing
to say is
you know the the initial idea really was
that
okay we're we have this
instead of what's great is we have this
thing that only works
that's very structured and has to
work in a certain way for it to make
sense
and um
but but then you ended up you ended up
in ten space time dimensions and so to
get back to physics you had to get rid
of five of the dimension six of
dimensions
and
the bottom line i would say in some
sense it's very simple that what people
just discovered is just
there there's kind of no particularly
nice way of doing this there's an
infinite number of ways of doing it and
you can get whatever you want depending
on how you do it so the you you end up
the whole program of starting at ten
dimensions and getting to four
just kind of collapses out of a lack of
any way to kind of get to where you want
because you can get anything
the hope around that problem has always
been that
the standard formulation that we have of
string theory which is
you can go in by the name perturbative
but it's kind of um
there's a standard way we know of given
a classical theory of constructing
a quantum theory and
and working with it which is
that's the so-called perturbation theory
that um that we know how to do
and that
that by itself just just doesn't doesn't
give you any hint as to what to do about
the six dimensions
so actual perturbed string theory by
itself really only works in 10
dimensions
so
you have to start making some kinds of
assumptions about how i'm going to
go beyond
this formulation that we really
understand of string theory and get rid
of these six six dimensions so kind of
the simplest one was the um
the claudio
postulate
but um
when that didn't really work out people
have tried more and more different
things and and the hope has always been
that
the solution
this problem would be that you would
find a a deeper and better understanding
of what string theory is that would
actually go beyond this perturbative
expansion and which would um which would
generalize this and and that once you
had that it would um
it would solve this problem of
it would pick out what to do with the
six dimensions how difficult is this
problem so
if i could restate the problem it seems
like there's a very consistent
physical world operating in four
dimensions
and uh how do you map a consistent
physical world in 10 dimensions to a
consistent physical world in four
dimensions right and how how difficult
is this problem is is that something you
can even answer
um
just
in terms of physics intuition in terms
of mathematics mapping from
ten dimensions to four dimensions well
basically i mean you have to get rid of
the of six of the dimensions so there's
i mean there's kind of two ways of doing
it one is what we call compactification
you say that
there really are 10 dimensions but for
whatever reason six of them are really
are so so small we can't see them
so you basically start out with ten
dimensions and what we call you know
make make six of them
not go out to infinity but just kind of
a finite extent and then make that size
go down
so small it's unobservable but that's
like that's a math trick
so
can you also help me build an intuition
about
how rich
and interesting the world in those six
dimensions is
because so compactification seems to
imply
well that's very interesting well no but
the problem is that what you learn if
you start doing math mathematics looking
at geometry and topology and in more and
more dimensions is that
i mean
asking the question like what are all
possible six dimensional spaces it's
just a it's kind of an unanswerable
question it's just uh i mean it's even
kind of technically undecidable in some
way they're just they're just too too
they're too many things you can do with
all these
if you start trying to make if you start
trying to make one-dimensional spaces
it's like well you got a line you can
make a circle you can make graphs you
can kind of see what you can do but as
you go to higher and higher dimensions
there's just so many ways you can
put things together of and get something
of that dimensionality and
so it it
unless you have some very very strong
principle which is going to pick out
some very specific
ones of these six dimensional spaces
and
they're just too many of them and you
can get anything you want but um so if
you have 10 dimensions
the kind of things that happen
say that's actually the way
that's actually the fabric of our
realities 10 dimensions there's a
limited set of behaviors of objects i
don't even know what the right
terminology to use that can
occur when within those dimensions like
in reality yeah
and so like
what i'm getting at is like is there
some consistent constraints
so if you have some constraints that map
to reality
then you can start saying like
dimension number seven is kind of boring
all the excitement happens in the
spatial dimensions one two three yeah
and time is also kind of boring
yeah and like
some are more exciting than others or we
can use our metric of beauty
some dimensions are more beautiful than
others once you have an actual
understanding of what actually happens
in those dimensions in our physical
world as opposed to sort of all the
possible things that could happen in
some sense i mean just the basic factors
you need to get rid of them we don't see
them so you need to somehow explain them
what you have to the main thing you're
trying to do is to explain why we're not
seeing them
and so you can you have to come up with
some theory of these extra dimensions
and how they're going to behave and
string theory gives you some ideas about
how to do that but
but
the bottom line is where you're trying
to go with this whole theory you're
creating is
to just make all of its effects
essentially unobservable so it's a it's
not a really
it
it's an inherently kind of dubious and
worrisome thing that you're trying to do
there why are you just
adding in all the stuff and then trying
to explain why we don't see it i mean
it's just good this may be a dumb
question but it's is this an obvious
thing to state
that
those six dimensions are unobservable or
anything beyond four dimensions is
unobservable or
do you leave a little door open to
saying
the current tools of physics
and obviously our brains aren't unable
to observe them
yeah but we may need to come up with
methodologies for observing so as
opposed to collapsing your mathematical
theory into four dimensions
leaving the door open a little bit too
maybe we need to come up with tools that
actually allow us to directly measure
those dimensions
yes i mean but you mean you can
certainly ask you know assume
that that we've got
model look look at models with more
dimensions and ask you know what would
the observable effects how would we
know this and you go out and do
experiments so for instance
you have a
like
gravitationally you have an inverse
square law of forces okay if you had
more dimensions that inverse square law
would change something else
so you can go and start
measuring the inverse square law and say
okay an inverse square law is working
but maybe if i get get and it turns out
to be actually kind of very very hard
measuring gravitational effects and even
kind of
you know somewhat macroscopic distances
because they're so small so you can you
can start looking at the inverse square
law and say start trying to measure it
at shorter and shorter distances and see
if there were extra dimensions at those
distance scales you would start to see
the inverse square law fail and um so
people look for that and again you don't
see it but
you can i mean there's all sorts of
experiments of this kind you can you can
imagine which test
for effects of extra dimensions at
different at
different distance scales but
you know none of them
i mean they they all just don't work
nothing yet i think yeah but you could
say ah but it it's if it's just it's
just much much smaller you can say that
which by the way makes ligo and
the detection of gravitational waves
quite an incredible project
ed whitten
is often brought up as one of the most
brilliant mathematicians and physicists
ever
what do you make of him and his work on
string theory
well i think you know he's a truly
remarkable figure i've
you know had the pleasure of meeting him
first when he was a postdoc and um i
mean he's a
just completely
amazing um mathematician and physicist
and uh you know he's
quite a bit smarter than just about
about any of the rest of us and also
more hard working and it's a it's a kind
of frightening combination to see how
much he's
been able to do
and um but i would actually argue that
you know his his greatest work the
things that he's done that have been of
just this mind-blowing significance of
giving us i mean he's completely
revolutionized some areas of mathematics
he's totally revolutionized the way we
understand the relations between
mathematics and physics
and most of those
his greatest work is is stuff that
doesn't have has little or nothing to do
with string theory i mean for instance
he um
you know he so he was actually one of
fields the very strange thing about him
in some sense is that he um
he doesn't have a nobel prize so there
there's a very large number of people
who are
nowhere near as smart as he is when
don't work anywhere near as hard who
have nobel prizes i think he just had
the misfortune of
coming into the field at a time when
things had gotten much much much tougher
and nobody really had
no matter how smart you were it was very
hard to come up with a new idea that was
going to work physically and get you a
nobel prize
but he but he um you know he he got a
fields medal for
a certain work he did in um in
mathematics and that's just completely
unheard of you know for mathematicians
to give a field medal to someone outside
their field and physics is really um
you know you wouldn't have before it he
came around i don't think anybody would
have thought that was even conceivable
these things um
he came into the field of theoretical
physics at a time when um
and still to today
is you can't get a nobel prize for
purely theoretical work a specific
problem of trying to do better than the
standard the standard model is just
this insanely successful thing and it
kind of came together in 1973 pretty
much
and post and so and and all of the
people who kind of were involved in that
coming together you know many of them
ended up with nobel prizes for that but
but if you look
post 1973 pretty much it it's a little
bit more there's some
edge cases if you like but the if you
look post 1973 at what people have done
to try to do better than the standard
model and to get a better unified theory
it really hasn't it's been too hard a
problem it hasn't worked the theory is
too good and so it's not that other
people
went out there and did and did it and uh
not him and that they got nobel prizes
for doing it is that no one really the
kind of thing he's been trying to do
with string theory is not um no one has
been able to do since 1973.
is there something you can say about the
standard model so the four laws of
physics that seems to work very well and
uh
yet people are striving to do more
talking about unification so on why
what's wrong what's broken about the
standard model
why why does it need to be improved i
mean the thing which gets most attention
is um
is gravity that we have trouble um
so you want to you want to in some sense
integrate
integrate what we know about the
gravitational force with it and have a
unified quantum field theory that has
gravitational interactions also so
that's the big problem everybody talks
about um
i mean
but but it's also true that if you look
at the standard model it has these very
very deep beautiful ideas but
there's certain aspects of it that are
very
let's just say that they're not
beautiful they're not um
you have to to make the thing work you
have to throw in
lots and lots of extra parameters at
various points
um and a lot of this has to do with the
so-called uh
you know the so-called higgs mechanism
in the higgs field that if you look at
the theory it's
everything is if you forget about the
higgs field and what it needs to do
the rest of the theory is
is very very constrained and has very
very few free parameters really a very
small number there's a very small number
of parameters and a few integers which
tell you what the theory is
to make this work as a theory of the
real world you need a higgs field and
you need to
it needs to do
to do something and
once you introduce that higgs field all
sorts of parameters
um make an appearance so now we've got
20 or 30 or whatever whatever parameters
that are going to tell you what all the
masses of things are and what's going to
happen so you've gone from
a very tightly constrained thing with a
couple parameters to uh
this this thing which the minute you put
it in you had to add all this extra
all these extra parameters to make
things work and so that
it may be one argument as well that's
just the way the world is and
the fact that you don't find that
aesthetically pleasing is just your
problem or
maybe we live in a multiverse and those
numbers are just different in every
universe but but you know another
reasonable conjecture is just that well
this is just telling us that there's
something we don't understand about
what's going on in a deeper way which
would explain those numbers and there's
some kind of
deeper idea about where the higgs field
comes from and what's going on
which we haven't figured out yet and
that's
that's what we should look for but to
stick on string theory a little bit
longer
could you play devil's advocate
and
try to argue for string theory
why it is something that
deserved the effort that it got
and still con
like if you think of it as a flame still
should be a little flame it keeps keeps
burning well i i think the i mean
the most positive argument for it is is
all the um
you know all sorts of new ideas about
mathematics and about parts of physics
really emerged from it so it was very a
fruitful
source of
ideas and i think you know this is
actually one argument you'll definitely
which i kind of agree with i'll hear
from from whitten and from other
strength here i said you know this is uh
this is just such a fruitful and
inspiring idea and it's led to so many
other different things coming out of it
that you know there must be something
right about this
and um yeah that's you know okay that
anyway i think that that's probably the
strong the strongest thing that they
that that they've got um but you you
don't think there's
aspects to it that could be uh
neighboring to to just to a theory that
does unify everything to a theory of
everything like it could it may not be
exactly um
uh exactly the theory but uh sticking on
it longer might get us closer to the
theory of everything
well the problem now really is that you
really don't know what it is now you've
never nobody has ever kind of come up
with this non-perturbative
theory so there
it's become more and more
frustrating and an odd activity to try
to argue with the string theorists about
string theory because it's become
less and less well-defined what what
what it is
and it's become actually more and more
kind of uh whether
you have this weird phenomenon of people
calling themselves string theorists
when they've never actually worked on
any theory were there any strings
anywhere
so what has actually happened kind of
sociologically is that
you started out with this fairly
well-defined proposal and then
i would argue because that didn't work
people and
branched out in all sorts of directions
doing all sorts of things it became
farther and farther removed from that
and for sociological reasons the ones
who kind of
started out
or now or or were trained by the people
who worked on that have now
become this string string theorist and
um
and
but but but it's become
almost more kind of a tribal denominator
than a um
i think so it's very hard to know what
you're arguing about when you're arguing
about string theory these days well to
push back on that a little bit i mean
string theory it's just a term right it
doesn't
like you could uh like this is the way
language evolves
is it could start to represent something
more than just the theory that involves
strings it could represent the uh the
effort
to unify the laws of physics right yeah
and uh at high dimensions with these
super tiny objects right or something
like that
i mean we can sort of uh put string
theory aside so for example neural
networks in the space of machine
learning
there was a
time when they were extremely popular
they became much much less popular to a
point where if you mentioned you'll
never gain no funding
and uh you're not going to be respected
at conferences and then once again
uh you know networks became all the all
the rage about 10 15 years ago and as it
goes up and down and a lot of people
would argue that uh using terminology
like machine learning and deep learning
is um
is
you know often misused over general
you know everything that works is deep
learning everything that doesn't isn't
yeah something like that you know that's
just the way uh
again we're back to sociological things
but i guess what i'm trying to get at is
if if we leave the sociological mess
aside
uh do we throw out the baby with the
bath water is there some
besides the side effects of nice ideas
from the edwins of the world
is there some core truths there
that we should stick by
in in in the full
beautiful mess of a space that we call
string theory that people call string
theory
you're right it is kind of a common
problem that you know how what your what
you call some field
changes and evolves in
interesting ways as the field changes
but
i mean
i guess
what i would argue is the you know the
initial understanding of string theory
that was quite specific we're talking
about a specific idea 10-dimensional
super strings compactified in six
dimensions
to my mind the
the really bad thing that's happened to
the subject is that
you it's hard to get people to admit at
least publicly that that was a failure
that this really didn't work
and so
the fact facto what people do is people
stop doing that and they start doing
more interesting things but they keep
telling talking to the public about
about string theory and
referring back to that idea and using
that as kind of the starting point and
this kind of the
the place where the
the whole
where the whole tribe starts and
everything else comes from and so the
problem with this is that having as your
as your initial name and what what
everything points back to
something which
um
which really didn't work out it kind of
makes everybody makes everything you've
created this potentially very very
interesting field with interesting
things happening but
you know
people
in
graduate school take courses on string
theory and everything kind of and this
is what you tell the public in which you
continually pointing back so you're
continually pointing back to this idea
which never worked out as you're
guiding
inspiration and it really kind of
deforms the whole your whole way of um
your your hopes of making progress and
that's to me i think you know the kind
of worst thing that has happened in this
field okay so there's a lack of
transparency and sort of authenticity
about communicating the things that
failed
uh in the past and so you don't have a
clear picture of
like firm ground that you're standing on
again those are sociological things and
yeah
i i
there's a bunch of questions i want to
ask you so one
what's your intuition about
um
why the original idea failed so what can
you say about
why you're pretty sure has it has failed
you know and the initial idea was as i
tried to explain it it was quite
seductive in that that you you could see
why whitton and others got excited by it
it was um
you know
at the time it looked like there were
only a few these possible claudios that
would work and it looked like okay we
just have to understand this very
specific
model in these very specific six-special
spaces and we're going to get everything
and so it was a very subjective idea but
it just
you know as people
learn worked more and more about it it
just didn't um
they just kind of realized that they're
just more and more things you can do
with these six dimensions and you can't
and this this is just not going to work
meaning like it's
i mean
what was the failure um
mode here is is you could just have an
infinite number of possibilities that
you could do so it's you can come up
with any theory you want you can fit
quantum mechanics you can
you can explain gravity you can explain
anything you want with it right is that
the basic failure mode yeah so it's a
failure mode of kind of that this idea
ended up
being kind of being essentially empty
that it it just didn't
doesn't ends up not telling you anything
because it's consistent with
just about just about anything
and so i mean there's a complex if you
try and
talk with strengtheners about this now i
mean there's a there's an argument
there's a long argument over this about
whether um
you know
oh no no no maybe there still are
constraints coming coming out of this
idea or not and or maybe we live in a
multiverse and
you know everything is true anyway so
you can there are various ways you can
kind of the strength here as i kind of
react react to this kind of argument
that i'm making but
try to hold on to it
um what about experimental validation is
that uh
is that a fair
standard to hold before
a theory of everything that's trying to
unify quantum mechanics and gravity yeah
i mean ultimately to be really convinced
that you know that on some new you know
idea but unification really works you
need some kind of uh you need to look at
the real world and see that this is
telling you something
something true about it i mean you know
either either
telling you that if you do some
experiment and go out and do it you'll
get some unexpected result and
that's the kind of gold standard or it
may be
just that like all those numbers that
are we don't know how to explain it it
will show you how to calculate them i
mean you can it can be various kinds of
experimental validation but that that's
certainly ideally what you're looking
for
how tough is this do you think for a
theory of everything not just string
theory so for something that unifies
gravity in quantum mechanics so the the
very big and the very small
is this uh
let me ask it one way is is it a
physics problem a math problem or an
engineering problem
my guess is it's a combination of a
physics and a math problem that you
really need
it's it's not really interesting it's
not like there's some kind of
well-defined thing you can write down
and we just don't have enough computer
power to do the calculation that's not
the kind of problem it is at all
but the question is you know what
mathematical tools you need to properly
formulate the problem
is unclear so one reasonable conjecture
is the way the reason that we haven't
had any success yet is just that um
we're missing
either we're missing certain
physical ideas or we're missing certain
mathematical tools which
or some combination of them which would
which we need to kind of properly
formulate the problem and see and and
see that it
it has a solution that looks like the
real world but those you need uh i guess
you don't but
there's a sense that uh you need both
gravity
like all the laws of physics to be
operating on the same level so this
isn't it feels like you need an object
like a black hole or something like that
in order to make predictions about
otherwise you're always making
predictions about this joint
phenomena
or or can you do that as long as the
theory is consistent and doesn't have
special cases for each of the functions
well your theory should i mean if your
theory is going to include gravity our
current understanding of gravity is that
you should have um
there should be black hole states in it
you should be able to describe black
holes in this theory and um and just one
aspect that people concentrate a lot on
is just this
kind of questions about if your
theory includes black holes like it's
supposed to and it includes quantum
mechanics then there's certain kind of
paradoxes which come up and so that's
that's been a huge focus of kind of
quantum gravity work work has been just
those paradoxes
so stepping outside of string theory uh
can you just say first at a high level
what is the theory of everything what
does the theory of everything seek to
accomplish
well i mean this is very much a kind of
reductionist point of view in the sense
that so it's not a theory this is not
going to explain
to you you know
anything it doesn't really this kind of
theory the theory this kind of theory of
everything we're talking about doesn't
say anything interesting particularly
about like macroscopic objects about
what the weather is going to be tomorrow
or
you know things are happening at this
scale but
just what we've discovered is that as
you look at um
the universe that kind of
you know if you
kind of start brit you can start
breaking it apart into and you end up
with some fairly simple pieces quanta if
you like and which are doing which are
interacting in some fair in some fairly
simple way
and it's um
it's good so what we mean by the theory
of everything is
a theory that describes all
all the objects all the correct objects
you need to describe what's happening in
the world and describes how they're
interacting with each other at a most
fundamental level how you get from that
theory to
describing some macroscopic incredibly
complicated thing is there that becomes
again more of an engineering problem and
you may need machine learning or you
made you know a lot of very different
things to do it but i don't even
think it's uh just engineering it's also
science it one thing that i find
um
kind of interesting
talking to physicists is is a little bit
there's a
a little bit of hubris so some of the
most brilliant people i know are
physicists both philosophy and just in
terms of mathematics in terms of
understanding the world but there's a
kind of uh either a hubris or what would
i call it
uh
like a confidence that if we have a
theory of everything we will understand
everything like this is the deepest
thing to understand and i would say
and like the rest is details right
that's the the old rutherford thing uh
but
to me
there's like this is like a cake or
something there's layers to this thing
and each one has a theory of everything
yeah like at every level
from biology like how life originates
that itself like complex systems yeah
like that in itself is like this
gigantic thing that requires a theory of
everything and then there's the in the
space of humans psychology like
intelligence collective intelligence the
way it emerges among species
that feels like a complex system that
requires its own theory of everything
on top of that
is
things like in the computing space
artificial intelligence systems like
that feels like it is a theory of
everything and it's almost like
once we solve
once we come up with the theory of
everything that explains the basic laws
of physics that gave us the universe
even stuff that's super complex like uh
how like how the
universe might be able to originate even
explaining something that you're not a
big fan of like multiverses or stuff
that we don't have any evidence of yet
still we won't
be able to
have a strong explanation
of uh
why
food tastes delicious oh yeah yeah i
know no anyway i yeah i agree completely
i mean this
there is something kind of completely
wrong with this terminology or theory of
everything that it's not um it's really
in some sense very bad term very
hubristic and bad
terminology because it's not um this is
explaining
this is a purely kind of reductionist
point of view that you're trying to
understand
certain a certain very specific kind of
things which
you know in principle
other things
you know emerge from but
to actually understand how anything
emerges from this is it's hope it can't
be understood in terms of
this this underlying fundamental theory
is going to be
hopeless in terms of kind of telling you
what about this um
this various emergent behavior and as
you go to different levels of
explanation you're going to need to
develop new you know different
completely different ideas completely
different ways of thinking and
i guess there's a famous kind of um
phil anderson's
slogan is that you know more is
different
and then yeah so it and
it's just it's just
even once you understand how what a
couple things well if you have a
collection of stuff and you understand
perfectly well how each thing is
interacting with it
with the others what the whole thing is
going to do is just a completely
different problem it's just not and you
need completely different ways of
thinking about it what do you think
about this
i got to ask you at a few different
attempts at the theory of everything
especially recently uh so
i've been
for many years a big fan of cellular
automata of complex systems and
obviously if because of that a fan of
stephen wolfram's work on in that space
but he's recently been talking about a
theory
of everything through his physics
project essentially
uh what do you think about this kind of
discrete
theory of everything for like from
simple rules and simple objects on the
hyper graphs emerges all of our reality
where time and space are emergent
basically everything we see around us is
immersed yeah yeah i i have to say
unfortunately i have kind of pretty much
zero sympathy for that i mean i don't um
i spend a little time looking at it and
i just don't see
it doesn't seem to me to get anywhere
and it really is just really really
doesn't agree at all with what what with
what i'm seeing this the kind of
unification of math and physics that i'm
kind of talking about around certain
kinds of very deep ideas about geometry
and stuff this
if you want to believe that
that your things are really coming out
of cellular automata at the most um
fundamental level you have to believe
that everything that i've
seen my whole career and as
as beautiful powerful ideas that that's
all just kind of a mirage which just
kind of randomly is emerging from these
more basic very very simple-minded
things and i
you have to give me some serious
evidence for that and i'm saying nothing
so mirage you don't think there could be
a consistency
where
things like quantum mechanics
could emerge from much much much smaller
discrete
like computational type systems i think
from the point of view of certain
mathematical point of view quantum
mechanics is already
mathematically as simple as it gets it
really
is a story about really
the fundamental objects that you work
with in when you write down a quantum
theory are in some in some point of view
precisely the fundamental objects
at the deepest levels of mathematics
that you're working with they're exactly
the same
so
and cellular automata are something
completely different which don't fit
into these structures and so i just
don't see why anyway i don't see it as a
promising
uh
you know promising thing to do and then
just looking at it and saying does this
go anywhere does this solve any problem
that i've ever
that i didn't does this solve any
problem of any kind i just don't see it
yeah to me cellular automata and these
hypographs
i'm not sure solving a problem
is even the standard to apply here at
this moment to me
the fascinating thing is that the
question it asks have no good answers so
there's not good math explaining forget
the physics of it math explaining the
behavior of complex systems yeah and
that to me is
both exciting and paralyzing like we're
at very early days of understanding
you know
how complicated and fascinating things
emerge from simple rules yeah you know i
agree i think that is a
truly great problem and
depending where it goes it may be um
you know
it may
start to develop some kind of
connections to the
the things that i've kind of found more
fruitful and
hard to know it just i think
a lot of that area i i kind of strongly
feel i
best
not say too much about it because i just
i don't know too much about it and uh i
mean again we're back to this original
problem that you know your time in life
is uh
is limited you have to figure out what
you're going to spend your time thinking
about and that that's something i've
just never seen enough to convince me to
spend more time thinking about it well
also timing it's not just that our time
is limited but
the timing of the kind of things you
think about there there's some
aspect to cellular autonomy these kinds
of objects that it feels like
we're very many years away from having
big breakthroughs on
and so it's like you have to pick the
problems that are solvable today in fact
my intuition
again not perhaps biased
is it feels like the kind of systems
that complex systems that cellular
automata are
would not be solved by human brains
it feels like well like it feels like
something post-human that will solve
that problem or like significantly
enhance humans meaning like using
computational tools
very powerful computational tools
to us to to crack these problems open
um
that's that's if our
approach to science our ability to
understand science our ability to
understand physics will become more and
more computational or there'll be a
whole field that's computational nature
which currently is not the case that
currently computation is the thing that
sort of
assists us
in um
understanding science the way we've been
doing it all along but if there's a
whole new i mean that
world from new kind of science right
it's a little bit dramatic but you know
this
if computers could do science on their
own computational systems
perhaps
um
that's the way they would do the science
they would try to understand the
cellular automata and that feels like
we're decades away so
perhaps he'll crack open some
interesting facets of this physics
problem but it's it's very far away so
timing is everything that that's
perfectly possible yeah
uh well let me ask you then in the space
of geometry
i don't know how well you know eric
weinstein oh bro quite well
what are your thoughts about
his geometric community and the space of
ideas that he's playing with
on
in his proposal for a theory of
everything well i i think that he has
he fundamentally has i think the same
problems that everybody
has had
trying to do this and you know they're
various they're really versions of the
same problem that you try to um
you try to get unity by put it putting
everything into some bigger structure so
he's
has has has some other ones that he that
are not so conventional that he's trying
to work with but um
he has that he has the same problem that
even if he can
if he can get a lot farther in terms of
having a really well-defined
well-understood clear picture of this
these large these things he's working
with they're really kind of large
geometrical structures with many
dimensions many kinds and i just don't
see any way
he's going to have the same problem the
string leaders have how do you get back
down to
the structures of the standard model and
how do you um
yeah so i i just
anyway
it's the same
and there's another interesting example
of some similar kind of thing is um
garrett lucy's
theory of everything again you know he's
there it's a little bit more specific
than eric's he's
working with this e8 but it um
again
i think all these things found her at
the same point that you don't
you know you create this unity but then
you have no
you don't actually have a good idea how
you're going to get back to the to the
actual
to the objects we're seeing how are you
going to you create these big symmetries
how are you going to break them and and
because because we don't see those
imageries in in the real world and um so
ultimately there would need to be a a
simple
process
for collapsing it to four dimensions
you'd have to explain well yeah and i
forget in his case but it's not just
four dimensions it's also these um
these structures you see in the standard
model there's a
you know there's certain very small
dimensional groups of symmetry so called
u1 su-2 and su-3 and
the problem with
and this has been the problem since the
beginning almost immediately after 1973
about a year later two years later
people started talking about grand
unified theories so you take
the u1 the su-2 and the su-3 and you put
them in together into this bigger
structure called the su5 or so10
but then
you're stuck with this problem that wait
a minute now how
why does the world not look why do i not
see
the these su5 symmetries in the world i
only see these and so
and and i think you know those id
the kind of thing that that that eric
and all sudden garrett and lots of
people try to do they all kind of found
her in that same
in that same way that they don't have
they don't have a good answer to that
are there lessons ideas to be learned
from theories like that from gary leases
from eric's
um i don't know it depends i have to
confess i haven't looked that closely at
a
at uh at eric's i mean he explained to
this to me um personally uh a few times
i've looked a bit at his paper but it's
um
again we're back to the problem of a
limited amount of time in life and
yeah i mean it's an interesting effect
right
why don't more physicists look at it
there
i mean i i'm in this position that
somehow
you know
uh
i've of uh
people write me emails for whatever
reason
and i'd work in the space of ai and so
there's a lot of people perhaps ai is
even way more accessible than physics in
a certain sense it's a lot of people
write to me with different theories
about they have for how to create uh
general intelligence
and it's again a little bit of an excuse
i say to myself like well i only have a
limited amount of time so that's why i'm
not investigating it but i wonder if um
there's ideas out there
that are still powerful they're still
fascinating and that i'm missing because
i'm
because i'm dismissing them
because they're outside of the sort of
the usual process of academic research
yeah well i mean the same thing and
pretty much every day in my email
there's a somebody's got a
theory of everything about why all of
what physicists are doing
perhaps the most disturbing thing i
should say about my uh critique being a
critic of string theory is is that when
you realize who your fans are
um that they
every day i hear from somebody that oh
well since you don't like string theory
you must of course agree with me that
this is the right way to think about
everything
oh no oh no
and you know
most of these
are you know you quickly you can see
this is person doesn't know very much
and doesn't know what they're doing you
know but there's a whole continuum to
you know people who are quite serious
physicists and mathematicians who are
making a fairly serious attempt to try
to to do something and like like eric
and uh and eric and then
then your your problem is
you know you spent you
you do so won't try to spend more time
looking at it and try to figure out what
they're really doing but
then at some point you just realize wait
a minute you know for me to really
really understand exactly what's going
on here would just
take
time i just don't have
yeah it takes a long time which is the
nice thing about ai
is unlike the kind of physics we're
talking about
if your idea is good
that should
quite naturally lead to you being able
to build a system that's intelligent
so you don't need to get approval from
somebody that's saying you have a good
idea here you can just utilize that idea
and engineer a system like naturally
leads to engineering with physics here
if you have a
perfect theory that explains everything
that still doesn't obviously lead one to
um
to scientific experiments that can
validate that theory and two to like uh
trinkets you can build and sell right
right at a store for five dollars i
can't make money off of it
[Laughter]
so that that makes it much much more
challenging um
well let me also ask you about something
that you found especially recently
appealing which is roger penrose's
twister theory
what is it what kind of questions might
it allow us to answer
what will the answers look like it's
only in the last couple years i really
really kind of come to really i think to
appreciate it and to see how to really
what i i believe to see how to really do
something with it and i've gotten very
excited about that last year too i mean
one way of saying
one idea of twister theory is that what
it's it's it's a different
way of thinking about
what space and time are and about what
points in space and time are
but but which only which is very
interesting that it only really works in
four dimensions so four dimensions
behaves very very specially unlike other
dimensions and in four dimensions
there's certain
there is a way of thinking about
space and time geometry where you know
as well as just thinking about
points in space and time
you can also
um
think about different objects it's all
called twisters and then when you do
that you end up with a um kind of a
really interesting insight that the um
that
you can formulate a theory and you can
formulate a very take a standard theory
that we formulated in terms of points of
space and time and you can reformulate
in this twister language and in this
twister language it's the um
the fundamental objects actually are
more kind of the
are actually spheres in some sense kind
of the light cone so maybe one
way to say it which actually i think is
is really
is quite amazing is if you ask yourself
you know what do we know about about the
world we have this idea that
the world out there is this all these
different points in these points
well that's kind of a derived quantity
what really really know about the world
is when we open our eyes what do you see
you see a sphere
and you and that what you're looking at
is you're looking at this you know a
sphere is worth a light rays coming into
into your eyes and what penrose says is
that
well what what a point in space-time is
is that sphere
that sphere of all the light rays coming
in and and he says and you should
formulate your um instead of thinking
about points you should think about the
space of those spheres if you like and
formulate the degrees of freedom as
physics that's living on those fears
living on so you're kind of you're kind
of living on your degrees of freedom are
living on light rays not on points
and it's a very different way of
thinking about um
about about physics and you know he and
others working with him developed a
you know a beautiful mathematical this
beautiful mathematical formalism and a
way to go back and forth between our
kind of some aspects of our standard way
we write these things down and
work on the so-called twister space and
you know they
certain things worked out very well but
they ended up
you know
i think kind of stuck by the 80s or 90s
that they weren't
a little bit like string theory that
they they um
by using these ideas about twisters they
could develop them in different
directions and find all sorts of other
interesting things but they were they
were getting they weren't finding any
way of doing that that brought them back
to kind of new insights into physics
and um my own i mean what's kind of
gotten me excited really is is that what
i think i have an idea about
that i think does actually does actually
work that goes more in that direction
and um i can go on about that endlessly
or talk a little bit about it but that's
the um
i think that that's the one kind of easy
to explain insight about twister theory
there are some more technical ones i
should mean i think it's also very
convincing what it tells you about
spinners for instance but that's more
technical well first let's like linger
on the spheres and the light cones
you're saying twisted theory allows you
to
make that the fundamental object with
which you're operating yeah
how that i mean first of all like
philosophically that's
weird
and beautiful
maybe because it maps
it feels like it moves us so much closer
to
the way human brains perceive reality
yeah so it's almost like um
our perception is
like the the content of our perception
is the fundamental object of reality
that's very appealing yeah
is it mathematically
powerful
is there something you can
say
can you say a little bit more about what
the heck that even means uh for because
it's much easier to think about
mathematically like a point
in space time like what does it mean to
be operating on the light cone
it uses a kind of mathematics that's
relative that you know what was kind of
goes back to the 19th century among
mathematicians it's not um
anyway it's a bit of a long story but
one problem is that you have to start
it's crucial that you think in terms of
complex numbers and not just real
numbers and
this for most people that makes it
harder to for mathematicians that's fine
we love doing that but for most people
that makes it harder to think about but
um i i think perhaps the most the way
that there is a uh something you can say
very specifically about it
you know in terms of spinners which i
don't know if you want to i think at
some point yeah
so maybe what are spinners let's start
with spinner because i think that if we
can introduce that then i can
by the way
twister spell with an o
and spinner is spelled with an o as well
yes okay
so in case you want to google it and
look it up that's very nice wikipedia
pages as a starting point i don't know
what is a good starting point for
twister theory
one thing you say about penrose i mean
penrose is actually a very good writer
and also very good draftsman he's on
drafts he to the extent this is
visualizable he actually has done some
very nice drawings so i mean almost any
kind of expository thing you can find
him writing is is a very good a good
place to start he's a
he's a remarkable person but the um
so
spinners are something that
independently came out of mathematics
and out of physics
and um to say where they came out of
physics i mean what people realized when
they started looking at elementary
particles like electrons
or whatever that there there seemed to
be
there seemed to be some kind of doubling
of the degrees of freedom going on if
you
counted
what was there in some sense in the way
you would expect it and when you started
doing quantum mechanics and started
looking at elementary particles there
were seem to be two degrees of freedom
they're not one
and one way of seeing it was that if you
if you put your electron in a strong
magnetic field
and asked and asked what was the energy
of it instead of it having one energy it
would have two energies there'd be two
energy levels and as you
increase magnetic field the splitting
would increase so
physicists kind of realized that wait a
minute so in we thought when we were
doing first start doing quantum
mechanics that the way to describe
particles was in terms of wave functions
and these wave functions were complex to
complex values well
if we actually look at particles that
that's not right there they're they're
pairs of complex numbers
and pairs of complex numbers
so you know why so one of the kind of
fundamental from the physics point of
view the fundamental question is why are
all our kind of fundamental particles
described by pairs of complex numbers
just weird and then but if you go and
then then you can ask you know what
happens if you like
take an electron and rotate it so how
how do things move in this this pair of
complex numbers
well now if you go back to mathematics
what had been
been understood in mathematics you know
some years earlier not that many years
earlier was that if you um
if you ask very very generally think
about geometry of three dimensions and
ask
and if you think about things that are
happening in three dimensions
in the standard way everything
the standard way of doing geometry
everything is about vectors right so if
you've
if you take any mathematics classes you
probably see vectors at some point
they're just triplets of numbers tell
you
what a direction is or how far you're
going in three dimensional space and
most of everything we teach in most
standard courses in
mathematics is about vectors and things
you build out of vectors so you express
everything about geometry in terms of
vectors or how they're changing or how
you put two of them together and get
planes and
whatever but what
had been realized that early on is that
if you ask very very generally what are
the
if you have
what are the things that that you can
kind of consistently think about
rotating
and um
and you can so you you ask a technical
question what are the representations of
the rotation group well
you you find that their one answer is
their vectors and everything you build
out of vectors
but then people found but wait a minute
there's also these other things
which you can't build out of vectors
but which you can consistently rotate
and they're they're described by pairs
of complex numbers by two complex
numbers and they're they're they're the
spinners also and
to make a lot and to make and and you
can think of spinners in some sense is
more fundamental than vectors because
you can build vectors out of spinners
you can take two spinners and make a
vector
but you can't
you can't if you only have vectors you
can't get spinners
so there in some sense at there's some
kind of level of lower level of geometry
beyond what we thought it was which was
kind of spinner geometry
and this is something which
even to this day when we teach graduate
courses in geometry we mostly
don't talk about this because it's a bit
it's a bit hard to hard to do correctly
if you start if you start with your
whole setup is in terms of vectors
getting describing things in terms of
spinners is a whole different ball game
but um the but so but anyway it was just
this amazing fact that this
this kind of more fundamental piece of
geometry spinners and what we were
actually seeing if you look at electron
are one in the same
so it's a
i think it's kind of kind of a
mind-blowing thing but it it's very uh
un counter-intuitive
what are some weird properties of
spinners that are currently
counter-intuitive
there are some things that they do for
instance if you rotate a spinner around
360 degrees it doesn't come back to
where it's it it becomes minus what it
was
so it's
anyway so so the way rotations work
there's a kind of a funny sign you have
to keep track of in some sense um so
they're kind of too valued in a way
another weird way but there's but but
the fundamental problem is that it's
just not
if you're used to visualizing
vectors you just there's nothing you can
do visualize in terms of vectors that
will ever give you a spinner it just is
not going to ever work
as you were saying that i was
visualizing a vector walking along a
mobius strip
yeah and it ends up being upside down
um but you're saying that doesn't really
capture
so i mean what really captures it the
pro the problem is that it's really
the simplest way to describe it is in
terms of two complex numbers and your
problem with two complex numbers is
that's four real numbers so
your spinner kind of lies in a four
dimensional space so you that makes it
hard to visualize and
it's crucial that it's not just any four
dimensions it's just it's actually
complex numbers you're really going to
use the fact that
these are the complex numbers so it um
it's very hard to visualize but but to
get back to what i think is mind-blowing
about twisters
is that the
another way of saying this this idea
about talking about spheres another way
of saying the fundamental idea of
twister theory is
in some sense the fundamental idea of
twister theory is that a point
is a two
is a two complex dimensional space so
that every
and that it lives inside the space that
it lies inside is twister space
so in the simplest case it's
for twister space is four dimensional
and
a point in space time is a two complex
dimensional
um
subspace of the f of all the four
complex dimensions and as you move
around in space time you're just moving
your planes are just moving around okay
and that
and but but then the it's a plane in a
four-dimensional space it's a yeah it
plays complex complex planes so it's two
complex dimensions in four comics
okay but then to me the mind-blowing
thing about this is this then
kind of tautologically answers the
question is what is a spinner well
a spinner is a point i mean the space of
spinners at a point is the point in
twister theory
the points are the complex two planes
and and you want me to and you're asking
what a spinner is
well a spinner the space of spinners is
that two plane
so it's you know just your whole
definition of what a pointed space time
was just
told you what a spinner was it's they're
they're just it's the same thing yeah
we're trying to project that into a
three-dimensional space and trying to
intuit but yeah
yeah so the intuition becomes very
difficult but um but
from if you don't you not using twister
theory
you have to kind of go through a certain
fairly complicated rigor role to even
describe spinners to describe electrons
whereas using twister theory it's just
completely tautological they're just
what you want
to describe
the electron is
fundamentally the way you're describing
the point in space-time already it's
just there
so
do you have a hope you mentioned that
you've been uh you found it appealing
recently is it just because of certain
aspects of its mathematical beauty or do
you actually have a hope that this might
lead to a theory of everything
yeah i mean i certainly do have
such a hope because what i've found i
think the thing which which i've done
which i i don't think as far as i can
tell no one had really looked at
from this point of view before
is
has to do with it this question of how
do you how do you treat time in your in
your quantum theory and um
so
there's another long story about how we
do
quantum theories and about how we treat
time and quantum theories which um
it is a long story but
to me the short version of it is that
what what people have found when you try
and write down a quantum theory
that
it's often
it's often a good idea to take
your time coordinate whenever you're
using your time coordinate and then
multiply it by the square root of minus
one and to make it purely imaginary and
so you all these formulas which you have
um
in your standard theory if you do that
to those i mean those those formulas
have some very strange
strange behavior and they're kind of
singular
if you ask even some simple questions
you have to very
take very delicate singular limits in
order to get the correct answer and you
have to take them from the right
direction otherwise it doesn't work
whereas if you just take time
and if you just put a factor of square
root of minus one wherever you see the
time coordinate
you end up with
much simpler formulas which are much
better behaved mathematically
and what i what i hadn't really
appreciated until fairly recently is
also how dramatically that changes the
whole structure of the theory you end up
with a consistent way of talking about
these quantum theories but it has very
some very different flavor and very
different aspects that i hadn't really
appreciated and in particular the way
the way symmetries act on it is is not
at all what i originally had expected
and so
that's the new thing that i've where i
think i think gives you something is to
um
to do this move which people often think
of as just kind of a
kind of a mathematical trick that you're
doing to make some formulas work out
nicely but to take that mathematical
trick as really fundamental
and um turns out in twister theory
allows you to simultaneously talk about
your usual time and the time times the
square root of minus one they both
fit they both fit very nicely into
twister theory and um you end up with a
some structures which look a lot like
the standard model
well let me ask you about some nobel
prizes okay
do you think there will be uh
uh there was a bet between um
michio kaku and somebody else uh about
john horgan here and john horgan about
uh
uh by the way maybe discover a cool
website longbets.com or dot org yeah
yeah it's cool it's cool that you can
make a bet with people
uh and then check in 20 years later
that's uh i really love it there's a lot
of interesting bets on there yeah i
would love to participate but it's
interesting to see you know time flies
yeah
and you make a bet about what's going to
happen 20 years you don't realize 20
years just goes like this yeah yeah and
then and then you get to face oh and you
get to wonder
like
what
was that person what was i thinking that
person 20 years ago is almost like a
different person what was i thinking
back then to think that
is interesting but so let me ask you
this on record
uh you know 20 years from now or some
number of years from now do you think
there will be a nobel prize given for
something directly connected to a first
broadly theory of everything
and second
of course one of the possibilities one
of them
string theory
um
strength
definitely not that uh things have gone
yeah
so fine if you were giving financial
advice you would say not to bet no do
not but
and and even i actually suspect if you
ask strength here is that question these
as you you're going to get a few of them
saying i mean if you'd asked them that
question 20 years ago again when
kaku was making this better whatever i
think some some of them would have taken
you up on it but um
and certainly back in 1984 a bunch of
them would have said oh sure yeah but
now i get the impression that
they've
even they realized that things are not
looking good for that particular idea
again it depends what you mean by string
theory whether maybe the term will
evolve to mean something else which
which will work out but i don't yeah i
don't think that's not gonna
likely to work out whether um
something else i mean i i still think
it's relatively unlikely that you'll
have any
really successful theory of everything
and and the main problem is is just the
um
it's become so difficult to do
experiments at higher energy that we've
really lost this ability to kind of get
unexpected input from
from experiment and and you can you know
while it's maybe hard to figure out what
people's thinking is going to be 20
years from now looking at um
you know energy particle energy
colliders and their technology it's
actually pretty easy to make a pretty
accurate guess what it's going to look
what
except what you're going to be doing 20
years from now and um
i think actually i
i would actually claim that
it's pretty clear where you're going to
be 20 years from now and what it's going
to be is you're going to have the
um you're going to have the the lhc
you're going to have a lot more data an
order of magnitude or more
or more
data from the lhc but at the same energy
you're not going to you're not going to
see a higher energy
accelerator operating successfully in
the um in the next 20 years and like
maybe machine learning or great sort of
data science methodologies that process
that data will not reveal any
major
like shifts in our understanding of the
underlying physics you think i don't
think so i mean i think that that that
feel that my understanding is that they
they're starting to make a great use of
those techniques but but it seems to
look like it it will help them solve
certain technical problems and be able
to do things somewhat better but not
completely change
the way they're looking at things what
do you think about
the potential quantum computers
simulating quantum mechanical systems
and through that sneak up
to sort of simu through simulation
sneak up to a deep understanding of um
the fundamental physics
the problem there is
that that's promising more for this um
for uh you know for phil anderson's
problem that you know if you want to
there there's lots and lots of if you
know
you take
you start putting together
lots and lots of things and we think we
know they're pair by pair interactions
but what this thing is going to do we
don't have any good calculational
techniques
you know quantum computers may very well
give you those and so they may
what we think of as kind of strong
coupling behavior we have no good way to
calculate
you know even though we can write down
the theory we don't know how to
calculate anything
with any accuracy in it the um quantum
computers may solve that problem but the
problem is that they i don't think that
they're going to solve the problem that
they help you with the problem of not
having their
of knowing what the right underlying
theory is
as somebody uh
who likes experimental validation let me
ask you the perhaps ridiculous sounding
but i don't think it's actually a
ridiculous question of
do you think we live in a simulation
do you find that thought experiment at
all useful or interesting
not really not not really i don't uh it
just doesn't uh
yeah and anyway to me it doesn't
actually lead to any kind of interesting
lead anywhere interesting and yeah to me
so maybe i'll i'll throw a wrench into
your thing uh
to me it's super interesting from an
engineering perspective so if you look
at virtual reality systems
the the actual question is
how much computation and how difficult
is it
to construct a world
that uh like there are several levels
here
one
is you won't know the difference our
human perception systems and maybe even
the tools of physics won't know the
difference between the simulated world
and the real world
that's sort of more of a
physics question
the the most interesting question to me
has more to do with why food tastes
delicious which is create how difficult
and how much computation is required to
construct a simulation
where you kind of know it's a simulation
at first
but you want to stay there anyway and
over time
you don't
even remember yeah
well yeah anyway i agree these are kind
of
fascinating questions and they may be
very very relevant to our future as a
species but um
yeah they're just very far from anything
so from a physics perspective it's not
useful to you to think
taking a computational perspective to
our universe think of it as an
information processing system
and then think of it as doing
computation and then you think about the
resources required to do that kind of
computation and all that kind of stuff
you could just look at the basic physics
and who cares what the the computer it's
running on us yeah it just i mean the
kinds of i mean
i'm willing to agree that you can get
into interesting kinds of questions
going down that road but they're just so
different from anything from what i
found interesting that i just
again i just have to
kind of go back to life is too short and
i'm very glad other people are thinking
about this but
i just don't see any anything i can do
with it
what about
space itself so i have to ask you about
aliens
again something uh since you emphasize
evidence
do you think there is how many do you
think there are and how many
intelligent alien civilizations are out
there
yeah i have i have no idea i have
certainly as far as i know unless the
government's covering it up or something
we haven't heard from uh
we don't have any evidence for
such things yet but there's there seems
to be no
there's no particular obstruction
why there shouldn't be so
i mean do you
you work on some
fundamental questions about the physics
of reality when you look up to the stars
do you think about whether somebody's
looking back at us
actually i originally got interested in
physics i actually started out as a kid
interested in astronomy exactly that and
a telescope and whatever that and
certainly read a lot of
science fiction and
thought about that i i find over the
years i find myself kind of less
anyway
less and less interested in that well
just because i don't i don't really know
what to do with them
i've also kind of kind of at some point
kind of stopped reading science fiction
that much kind of feeling that there was
just two that the actual science i was
kind of learning about was
perfectly kind of weird and fascinating
and unusual enough but and better than
any of the stuff that
and isaac asimov so why should i
yeah
and you can mess with the science
much more than the the distant science
fiction
yeah the one that's exist in our
imagination or the one that exists out
there among the stars yeah
well you mentioned science fiction
you've written quite a few book reviews
i gotta ask you about some books perhaps
if you don't mind
is is there one or two books that you
would recommend
to others and maybe if you can
what ideas you drew from them
either negative recommendations positive
well do not read this book for sure well
i must say i mean
unfortunately
yeah you can go to my website and
there's you can click on book reviews
and you can see i've written
read a lot of a lot of i mean
as you can tell from my views about
string theory i'm not a fan of a lot of
the kind of popular books about oh isn't
straight theory grade and
about
yeah so i'm not a fan of
a lot of things of that kind can ask you
a quick question on this a small tangent
are you a fan
okay can you explore the pros and cons
of forget string theory
sort of science communication
sort of cosmo style
communication of concepts to people that
are outside of physics outside of
mathematics outside of even the sciences
and helping people to sort of dream and
fill them with awe about the full
range of mysteries in our universe
that's a complicated issue i think
you know i certainly go back and go back
to like what inspired me and um maybe to
connect to connected a little bit to
this question about books i mean
certainly one
the books that some books that i
remember reading when i was a kid were
about the early history of quant
mechanics like heisenberg's books that
he wrote about you know kind of looking
back at telling the history of what
happened when he developed climate
change it's just kind of a
totally fascinating romantic
great story and uh those were very
inspirational to me
and um i would think maybe other people
might also
also find them that but the um and
that's that's almost like the human
story of the development of the ideas
yeah the human story but yeah just also
how you know they they're these very
very weird ideas that didn't seem to
make sense that how they were struggling
with them and how you know they actually
anyway it's it's it's it's i think it's
the period of physics kind of beginning
in 1905 plank and einstein and
ending up with the war when these things
are get used to you know make massively
destructive weapons is it's just that
truly amazing so many so many new ideas
let me on another tangent on top of a
change on top of a tangent ask
if we didn't have einstein
so how does science progress
is it the long geniuses
or is it uh some kind of weird network
of ideas swimming in the air and just
kind of the the geniuses pop up to catch
them and others would anyway without
einstein would we have
uh special relativity general relativity
i mean it it's an interesting case to
case based i mean i mean especially
special relativity i think we would have
had
i mean there are other people
anyway
you could even argue that it was already
there in some form in some ways but i
think special relativity would have had
without einstein fairly
fairly quickly general relativity
that was a much much harder thing to do
and um
required a much more effort much more
certificate that
i think he would have had sooner or
later but it would have taken taken
quite a bit longer
another thing that took a bunch of years
to validate scientifically the general
relativity but even for einstein from
you know the point which he had kind of
a general idea of what he was trying to
do to the point where he actually had a
well-defined theory that you could
actually compare to the real world that
was you know i kind of forget the
numbers of the order of magnitude 10
years of very serious work and um if he
hadn't been
around to do that it would have taken a
while before anyone else
got around to it on the other hand there
are things like
with quant mechanics you have um
you know heisenberg and um schrodinger
came up with two
which ultimately equivalent but two
different
approaches to it you know within months
of each other and you know so if
heisenberg hadn't been there he already
what about schrodinger or whatever and
if neither of them been there it would
have been somebody else a few months
later so
there are times when the um
you know just the
a lot often is
the combination of
the right ideas are in place and the
right experimental data is in place to
point in the right direction and it's
just waiting for
somebody's going to find it um
maybe maybe to go back to your uh to
your aliens i guess the one thing i
often wonder about aliens is would they
have the same
fundamental physics ideas as we if we
have in mathematics would their mouth
you know would they
you know
how much is this really intrinsic to our
minds if you start out with a different
kind of mind when you end up with a
different
ideas of what fundamental physics is or
what or what the structure of
mathematics is so this is why like if i
was uh
you know i like video games the way i
would do it as a curious being so first
experiment i'd like to do is run earth
over
many thousands of times and see if our
particular
um no you know what i wouldn't do the
full evolution i would start at homo
sapiens first and then see the evolution
of homo sapiens millions of times and
see how the the ideas of science would
evolve like
would you get
like how would physics evolve how would
math evolves i would particularly just
be curious about the notation they come
up with
um every once in a while i would like
throw miracles at them to like to mess
with them and stuff and then i would
also like to run earth from the very
beginning to see if evolution would
produce different kinds of brains that
would then produce different kinds of
mathematics and physics and then finally
i would probably millions of times run
the universe over to see what kind of um
what kind of environments
and what kind of uh life would be
created to then lead to intelligent life
to then lead to
um theories of mathematics and physics
synthesis the full range and like sort
of uh like darwin kind of mark okay
it took them uh
what is it
several hundred million years to come up
with uh
calculus
i would just like keep noting how long
it does and get an average and see see
which ideas are difficult which are not
and and then and then conclusively
sort of figure out if it's uh
if it's more collective intelligence or
singular intelligence that's responsible
for shifts and for big phase shifts and
breakthroughs in science
if i was playing a video game and
i got a chance to run this whole thing
yeah
but um
we were talking about books before i
distracted okay of course yeah go back
books and yeah so and then yeah so
that's one thing i recommend is the
books books about the
from the original people especially
heisenberg about the
how that happened and there's also a
very very good kind of history of
of the kind of what happened during this
20th century
in physics and you know up to the time
of the standard model in 1973 it's
called the um the second creation by um
pop crease and uh and man that's one of
the best ones i know that's
but the one thing that i can say is that
so that book i think
forget when it was late 80s 90s
the problem is that there just hasn't
been much that's actually worked out
since then so
most of the books that are kind of
trying to tell you about all the
glorious things that have happened since
1973 are
they're mostly telling you about how
glorious things are which actually don't
really work it's really
the argument people sometimes make in
terms in favor of these books as well oh
you know they're really great because
you want to do something that will get
kids excited and then you know so
they're getting excited about things
something that's not really quite
working it's doesn't really matter the
main thing is get them excited yeah the
other argument is
you know wait a minute when if you're
getting
people excited about ideas that are
wrong you're really kind of you're
actually kind of discrediting the whole
scientific enterprise in a not really
good way so there's
these problems so my uh
my general feeling about expository
stuff is yeah it's to the extent you can
do it kind of honestly and and and well
that's great there are a lot of people
doing that now but
to the extent that you're
just trying to get people
excited and enthusiastic by kind of
telling them stuff which isn't really
true this is you really shouldn't be
doing that
you obviously have a much better
intuition about physics i i tend to um
in the space of ai for example you could
you could use certain kinds of language
like calling things um intelligent
that could rub people the wrong way but
i never had a problem with that kind of
thing you know saying that a program can
learn its way without any human
supervision as
alpha zero does to play chess
to me that
may not be intelligence but it's sure
that as heck seems like
a few steps down the path towards
intelligence yeah and so like i think
that's a very peculiar
uh property of systems that can be
engineered so even if the idea is fuzzy
even if you're not really sure what
intelligence is
or um
like if you don't have a deep
fundamental understanding or even a
model what intelligence is if you build
a system that sure as heck is impressive
and showing some of the signs of what
previously thought impossible
for a non-intelligent
uh system then that's impressive and
that's inspiring and that's okay to
celebrate in physics
because you're not engineering anything
you're just now swimming in the space
directly when you do theoretical physics
that it could be more dangerous you
could be out
too far away from shore yeah well the
problem
i think if physics is it in a i think
it's actually hard for people even to
believe or really understand
how
that this particular kind of physicist
has gotten itself into a really unusual
and strange and historically unusual
state which is not really i mean i
spent half my life among mathematicians
and athletic physicists and you know
mathematics is kind of doing fine people
are making progress and it has all the
usual problems but also
so you could have a
but but you i just i don't know i've
never seen anything at all happening in
mathematics like what's happened in the
specific area in physics it's just
the kind of sociology of this the way
this field
works
banging up against this harder problem
without
anything from experiment to help it it's
really
it's led to some really kind of
problematic things and those so it's one
thing to kind of
you know oversimplify or to slightly
misrepresent to try to explain things in
a way that's not quite right but it's
another thing to start promoting to
people
as a successes ideas which which really
completely failed and um so i mean i'm
i've kind of a very very specific
if you so have people
won't name any names for instance coming
on certain podcasts like you're telling
the world you know this is a huge
success and this is really wonderful and
it's just not true
and and this is this this is really
problematic and it carries a serious
danger of um you know once
when people realize that this is what's
going on you know they
you know the the loss of credibility of
of science is is a real real problem for
our society and and you don't want
you don't want people to have an all too
good reason to
to think that what they're being
what they're being told by kind of some
of the best uh institutions in our
country or authorities is is not true
you know it is
it's not true it's a problem
that's it's obviously a characteristic
of not just physics it's uh
it's sociology yeah
and it's uh i mean obviously in the
space of politics it's the the history
of politics is uh
you um
you you sell ideas to people
even when you don't have any proof that
those ideas actually work if you speak
as if they've have worked and that that
seems to be the case throughout history
and just like you said it's human beings
running up against a really hard problem
i'm not sure if this is like a
particular
uh like trajectory through the progress
of physics that we're dealing with
knowledge it's just the natural progress
of science you run up against a really
difficult
stage of a field
and
uh
different people that behave differently
in the face of that
some sell books and sort of
tell narratives that are beautiful and
so on they're not necessarily grounded
in um solutions that have proven
themselves
others kind of uh put their head down
quietly keep doing the work others sort
of pivot to different fields and that's
kind of like yeah ants scattering and
then you have feels like machine
learning which is there's a few folks
mostly scattered away from machine
learning in the in the 90s in the winter
of ai ai winter as they call it but a
few people kept their head down and now
they're called the fathers of deep
learning yeah
and and they didn't think of it that way
um
and in fact if there's another yeah i
went to they'll just probably keep
working on it anyway sort of like loyal
ants
to a particular
sure yeah
so it's it's it's interesting but you're
sort of saying that um
we should be careful over hyping things
that have not proven themselves
because people will
lose
trust in the scientific process yeah but
unfortunately there's been other
ways in which people have lost trust in
the scientific process that ultimately
has to do actually with all the same
kind of behavior as you're highlighting
which is
not being honest and transparent about
the flaws
of mistakes of the past yeah i mean
that's always a problem but um this
particular field is kind of fun mostly
it it's a
it's always a strange one i mean i think
in the sense that
there's a lot of public fascination with
it that it seems to speak to kind of our
deepest questions about you know
what is this physical reality where do
we come from and what and these kind of
deep issues so there's there's this
unusual fascination with it mathematics
is versus very different nobody nobody's
that interested in mathematics nobody
really kind of expects to
learn really great
deep things about the world from
mathematics that much they don't ask
mathematicians that so
so so it's a very unusual it it draws
this kind of unusual amount of attention
and it really is historically in a
really unusual state it's kind of it's
gotten itself
way kind of down uh
down a blind alley in in in a way which
it it's hard to find other historical
parallels but sort of push back a little
bit there's power to inspiring people
and if i just empirically look
physicists
are really good
at
um combining
science and philosophy
and communicating it like there's
something about physics often that
forces you to build a strong intuition
about the way reality works
right and that allows you to think
through
sort of and communicate about all kinds
of questions like if you see physicists
it's always fascinating to take on
problems that have nothing to do with
their particular discipline they think
interest in interesting ways and they're
able to communicate their thinking
interesting ways and so in some sense
they have a responsibility not just to
do science but to inspire
and not responsibility but the
opportunity and thereby i would say
a little bit of a responsibility
yeah yeah and sometimes but um i know
anyway it's hard to say because because
different um there's many many people
doing this kind of thing with different
degrees of
of success and
whatever i i guess one thing um
but but i mean my what's kind of front
and center for me is kind of a more
parochial interest is just kind of what
what damage do you do to the subject
itself
ignoring
misrepresenting you know what high
school students think about string
theory and not that doesn't matter much
but but what the smartest
undergraduates or the smartest graduate
students in the world think about it and
what paths you're leading them down and
what story you're telling them and what
textbooks you're making them read and
what they're hearing and um and so a lot
of what's motivated me is more to try to
speak to
as kind of a specific population of
people to make sure that look you know
people
it doesn't matter so much what the
rest of what the average person on the
street thinks about string theory but
you know what
what what what the best students at
columbia or harvard or princeton or
whatever who are who really want to
change work in this field and want to
work that way what what they know about
it what they think about it and that
they not be go into the field being
misled and believing that a certain
story this is where this is all going
this is what i got to do um is it is
that's important to me well in general
for graduate students for uh people who
seek to be experts in the field
diversity of ideas is really powerful
and is getting into this local pocket of
ideas that people hold on to for several
decades is not good no matter what idea
i would say no matter if the idea is
right or wrong
because there's no such thing as right
in the long term like it's right for now
until somebody builds on
something much bigger on top of it it
might end up being ripe but being a a
tiny subset of a much bigger thing
so there you always should question sort
of the uh the ways of the past
yeah yeah so so how to kind of achieve
that kind of
diversity of thought and uh within kind
of the sociology of how we organize
scientific research researches i know
this is one thing that i think it's very
interesting that uh sabine hassenfelder
is very it's interesting things to say
about it and i think also at least mohan
in his book which is also about that
very
very much in agreement with them that
there's
anyway there's a really kind of
important
questions about you know how
how how research in this field is
organized and how people
you know
what can you do to kind of get and get
more diversity of thought and get more
to and get people thinking about um
about a wider range of ideas
at the bottom i think humility always
helps
well
but the problem is that it's also it's a
combination of humility to know when
when you're wrong and also
but also you have to have a you have to
have a certain very serious lack of
humility to believe that you're going to
make progress on some of these problems
i think you have to have like both modes
and switch between them when needed
let me ask you a question you're
probably not going to want to answer
because uh
you're focused on the mathematics of
things and mathematics can't answer the
why questions but
let me ask you anyway
do you think there's meaning to this
whole thing
what do you think is the meaning of life
why are we here
i don't i don't know yeah i
was thinking about this so the um
it did occur
one interesting
thing about that question is that you
don't you know so i have
this life in mathematics and this life
in physics and and i see
some of my physicist colleagues you know
kind of
seem to be people are often asking them
what's the meaning of life and they're
writing books about the meaning of life
and teaching courses about the meaning
of life and
but then i realized that no one ever
asked my mathematician colleagues
nobody ever asks mathematicians yeah
that's funny so
[Laughter]
yeah
everybody just kind of assumes okay well
you people are studying about that
actually whatever you're doing it's
maybe very interesting but it's clearly
not going to tell me anything useful
about the meaning of my life and i'm
afraid a lot of my point of view is that
if people realized how little difference
there was between what the
mathematicians are doing and what a lot
of these theoretical physicists are
doing they would they might understand
that
it's a bit misguided to look for
deep insight into the meaning of life
from from
from many theoretical physicists it's
not uh
they you know they're they're people
they have they may have interesting
things to say about this you're right
they have they know a lot about physical
reality and about
about
and sometimes about metaphysics about
what
is is real of this kind but um
you're also
to my mind i think you're also making a
bit of a mistake that you're you're
looking to uh
i mean i'm very very aware that you know
i've led a very
pleasant and fairly privileged existence
of a fairly
without many challenges of different
kinds of a certain kind and and um
i i'm really not in no way the kind of
person that
a lot of people who are looking for to
try and understand
in some meaning of life in the sense of
the challenges that they're facing in
life uh i can't really i'm really the
wrong person for you to be asking about
this well
if struggle is somehow a thing that's
core to meaning yeah perhaps
mathematicians are just quality the ones
who are
most equipped to answer that question if
in fact the creation or at least
experiencing beauty
is uh
is
is at the core of the meaning of life
because it seems like mathematics is the
methodology but which you can most
purely explore beautiful things
right yeah
so in some sense maybe we should talk to
mathematicians more
yeah yeah maybe but but the uh
unfortunately you know people do have a
somewhat correct perception that what
these people are doing every day
whatever is is pretty far removed from
anything
yeah from from what's kind of close to
what i'm
what i do every day and what my typical
concerns are so you may learn something
very interesting by talking to
mathematicians but it's uh
it's probably not going to be you're
probably not going to get what you were
hoping
so when you put the pen and paper down
and you're not thinking about physics
and you're not thinking about
mathematics and you just get to breathe
in the air and look around you and
realize that you're going to die one day
you know you think about that
um your ideas will live on but you the
human
not not especially much but certainly
i've been getting getting older i'm now
64 years old you start to realize well
there's
probably less ahead than there was
behind and so you start to
that starts to become you know wait what
do i think about that maybe i should
actually
get serious about some getting some
things done which i
which i may not have which i may
otherwise not have time to do which i
didn't see this didn't seem to be a
problem when i was younger but um
that's the main i think the main way in
which that thought occurs
but it doesn't uh you know the stoics
are big on this meditating on mortality
helps you
more intensely appreciate the beauty
when you do experience it
i suppose that's true but it's not yeah
it's not
not something i've spent
a lot of time trying but um but yeah
day to day you just enjoy the positive
mathematics just enjoy yeah or
our life in general life is
have a
perfectly pleasant life and enjoy enjoy
it and
often think wow this is i think things
are
i'm really enjoying those things are
going well
yeah life is pretty amazing yeah i think
you and i are pretty lucky we get to uh
live on this nice little earth yeah with
a nice little comfortable climate and we
get to have this
nice little podcast conversation thank
you so much for spending your valuable
time with me today and having this
conversation thank you glad thank you
thank you
thanks for listening to this
conversation with peter white to support
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and now let me leave you some words from
richard feynman the first principle is
that you must not fool yourself
and you
are the easiest person to fool
thank you for listening and hope to see
you next time
you