Kind: captions
Language: en
a black hole is a mirror
and the way it's a mirror is if light a
photon bounces off your face
towards the black hole and it goes
straight to the black hole just Falls in
you never see it again
but if it just misses the black hole
it'll swing around the back and come
back to you
and you see yourself
from the photon that went around the
back of the black hole
but not only can that happen
the black hole the photon can swing
around twice
and come back so you actually see an
infinite number of copies
of yourself
the following is a conversation with
Andrew strominger theoretical physicist
at Harvard whose research seeks to shed
light on the unification of fundamental
laws of nature the origin of the
universe and the quantum structure of
black holes and event Horizons this is
the Lux Friedman podcast the supported
please check out our sponsors in the
description and now dear friends here's
Andrew strominger
you are part of the Harvard black hole
initiative which has theoretical
physicists experimentalists and even
philosophers so let me ask the big
question what is a black hole from a
theoretical from an experimental uh
maybe even from a philosophical
perspective so a black hole is defined
theoretically
as a region of space-time
from which light can never Escape
therefore it's black
now that's just the starting point many
weird things uh follow from that basic
definition but that is
that is the basic definition what is
light
they can't escape from a black hole well
light is uh you know the stuff that
comes out of the Sun that stuff that
goes into your eyes
light is one of the the stuff that
disappears when the lights go off this
is stuff that appears when the lights
come on
um of course that could give you a Beth
a medical definition but or physical
mathematical definition but I think it's
something that we uh will understand
very intuitively
what is light black holes on the other
hand we don't understand intuitively
they're very weird
and
one of the questions is about black
holes which I think you were alluding to
is you know why doesn't light get out or
how is it that there can be a region of
space-time
from which light can't escape
it definitely happens we've seen those
regions we have spectacular pictures
especially in the last several years of
those regions
um they're there
in fact they're up in the sky thousands
or millions of them
we don't yet know how many
um but the proper explanation
of why light doesn't escape from
uh
a black hole is still a matter of some
debate
um
and
one explanation
which perhaps Einstein might have given
is that light carries energy
you know it carries energy because
you know we have uh photo cells and we
can take the light from the sun and
collect it turn it into electricity so
there's energy in light
and anything that carries energy is
subject to a gravitational pull
gravity will pull at anything with
energy
now it turns out that the gravital
gravitational pull
exerted by an object
uh is proportional to its mass
and so if you get enough Mass
in
a small enough region
um
you you can prevent light from escaping
and let me flesh that out a little more
um if you're
on the Earth
and you're on a rocket ship leaving this
the surface of the Earth and if we
ignore the friction from the air
um if your rocket accelerates up to 11
kilometers per second
that's escape velocity
and it can if there were no friction it
could just continue forever to the next
galaxy
on the moon which has less Mass it's
only seven kilometers per second
so but going in the other direction if
you have
enough mass in one place the escape
Velocity
can become the speed of light
if you shine light straight up away from
the earth it doesn't have too much
trouble it's going way above the escape
Velocity
and
um but if you have enough Mass there
even light can't escape the escape
Velocity and according to
Einstein's theory of relativity there is
an absolute speed limit in the universe
the speed of light
and nothing
makes any sense nothing could be
self-consistent if there are objects
that could exceed
light speed
and so uh in these very very massive
regions of space-time even light cannot
escape and the interesting thing is
Einstein himself didn't think that uh
these uh objects would call the black
holes could exist but let me actually
Linger on this yeah that's incredibly
interesting there's a lot of interesting
things here first of the speed limit
how Wild is it to you if you put
yourself in the mind in the time of
Einstein before him to come up with a
speed limit of that there is a speed
limit that and that speed limit is the
speed of light how difficult of an idea
is that is it you know you said from a
mathematic
mathematical physics perspective
everything just kind of falls into place
but he wasn't
perhaps maybe initially had the luxury
to think mathematically he had to come
up with it intuitively yes so like what
how common intuitive is this notion to
you well is it still crazy no no so it's
a very funny thing in physics the best
discoveries
seem completely obvious in retrospect
yeah
even my own discoveries which of course
are far lesser than Einsteins but many
of my papers many of my collaborators
get a little confused we'll try to
understand something we said we've got
to solve this problem we'll get all
confused finally we'll solve it we'll
get it all together
and
um
then we'll
all of a sudden everything will fall
into place we'll explain it and then
we'll look back at our discussions for
the precedings of months and literally
be unable to reconstruct
how confused we were yeah and how we
could ever have thought of it any other
way
so not only can I not fathom
how confused
Einstein was
before he when you know when he started
thinking about the issues I can't even
reconstruct my own confusion from from
two weeks ago uh you know so the really
beautiful ideas that physics have this
very hard to get yourself back into the
mindset of course Einstein was confused
about many many things
doesn't matter if you're a physicist
it's not how many things you got wrong
it's not the ratio of how many you got
wrong coming you got right it's the
number that you got right
so Einstein didn't believe black holes
existed even though he predicted them
and I went and I read that paper which
he wrote you know Einstein wrote down
his field equations and
1915 and short Shield solved them and
discovered the black hole solution
three or four months later in very early
and um 25 years later Einstein wrote a
paper so with 25 years to think about
what this solution means yeah wrote a
paper in which he said that black holes
didn't exist
and I I'm like whoa
you know if one of my students in my
general relativity course wrote this
you know I wouldn't pass them you get I
get to see mine oh you wouldn't pass
them okay all right good to see minus
okay same thing with gravity waves you
didn't believe oh he didn't believe in
gravitational waves either he went back
and forth but he wrote a paper and I
think 34 saying that gravity waves
didn't exist because it people were very
confused about what a coordinate
transformation is and in fact this
confusion about what a coordinate
transformation
is has persisted
and we actually think
we were on the
edge of solving it
a hundred years later
well what a hundred years later what is
coordinate transformation as it was a
hundred years ago to today let's imagine
I want to draw a map with pictures of
all the states and the mountains and
then I want to draw the weather forecast
what the temperatures are going to be
all over the country
and I do that using one set of weather
stations
and I number the weather stations
and you have some other set of
weather stations
and you
you do the same thing so the coordinates
are the locations of the weather
stations yeah they're how we describe
where the things are
at the end of the day
we should draw the same
map
that is coordinate invariance
and if we're telling somebody uh we're
going to tell somebody at a real
physical operation we want you to stay
as dry as possible on your drive from
here to California
we should give them exactly the same
route
no matter which weather stations we use
or how we you know it's a very trivial
it's it's the labeling of points is an
artifact and not in the real physics
sure
so it turns out that that's
almost true
but but not quite there's some
subtleties to it
the statement that you should always
have the same give it this the same kind
of trajectory the same kind of uh
instructions no matter the weather
station yeah yeah there's some very
delicate subtleties to that which
begin to be noticed in the in the 50s
it's mostly true but when you have a
space-time with edges
it gets very tricky how you label the
edges and space-time in terms of spacer
in terms of time in terms of everything
just based on either one okay space or
time that gets very tricky and Einstein
uh didn't
didn't didn't have it right and in fact
he had an earlier version of general
relativity
in 1914 which he was very excited about
um which was
wrong
um gave it wasn't fully coordinate and
variant it was only partially
coordinated variant it was wrong
it gave the wrong answer for bending
light to the Sun
by a factor of two
there was an expedition
sent out to measure it during World War
One
they were captured
before they could measure it and that
came that came Einstein four more years
to clean it to clean his act act up by
which time he had gotten it right
so it's a very it's a very tricky
business but once it's all laid out it
saves uh
it's it's it's clear then what do you
think Einstein
didn't uh believe his own equations and
didn't think that black holes are real
well why was that such a difficult idea
for him well something very interesting
happens in
short Shield solution of the Einstein
equation
I think his reasoning was ultimately
wrong but let me
explain to you uh
what it was
um
at the center of the black hole behind
the horizon
in a region that nobody can
see and live to tell about it
as a center of the black hole there's a
singularity and if you pass the Horizon
you go into the singularity you get
crushed and that's the end of everything
now the word singularity
means that
um
it just means that Einstein's equations
break down
they become infinite you write them down
you put them on the computer when the
computer hits that Singularity it
crashes
everything becomes infinite there's two
so the questions are just no good there
now
that's actually
not a bad thing it's a really good thing
and let me explain why
um
so
it's an odd thing
that Maxwell's Theory
and Newton's Theory
never
exhibit this phenomena you write them
down you can solve them exactly they're
really Newton's theory of gravity
they're really very simple theories you
can solve them well you can't solve the
three body problem but
um
you can certainly solve a lot of things
about them
nevertheless
there was never any reason
even though Maxwell and Newton perhaps
fell for this trap there were never any
reason to think that these equations
were exact
um and
every there's no equation
well
there's some equations that we've
written down that we still think are
exact
some people still think are exact my
view is that there's no exact equation
everything is an approximation
everything is an approximation are you
trying to get as close as possible yeah
so you think are you saying objective
truth doesn't exist in this world
we could discuss that but that's a
different that's a different thing
um we wouldn't say Newton's theory was
wrong
it had very very small Corrections Inc
incomplete small Corrections it's
actually a puzzle why they're so small
so if you watch the procession of
Mercury's perihelia this was the first
indication
of something going wrong according to
Newton's Theory mercury has an
elliptical orbit
the long part of it moves around
as other planets come by and perturb it
and so on and so this was measured by
leveria in 1859 and he compared
Theory and experiment and he found out
that the perihelion process moves around
the Sun
once every
233 centuries instead of every 231
centuries
okay now this is the wonderful thing
about science
why was this guy
are we didn't get any idea how much work
this is you know
but of course he made one of the
greatest discoveries of the history of
science without you know even knowing
what it what good it was going to be
so that's how small that that was the
first sign that there was something
wrong with Newton yeah
nah so the corrections to Newton's law
are very very small but they're
definitely there
the corrections to electromagnetism
they're mostly the ones that we see are
mostly coming from Quantum effects
and so so the corrections there for uh
Maxwell's equations is when you get
super tiny and then the corrections for
the
um for Newton's uh laws gravity is when
you get super big
that though that's when you acquire
Corrections that's true but I would
phrase it as saying when it's super
accurate you know if you look at the
Bohr atom
Maxwell electromagnetism is not a very
good approximation
to the force between the proton and the
electron the quantum mechanics
if you if you if you didn't have quantum
mechanics the electron would would
spiral into the proton and the atom
would collapse it's Quantum you know so
that's a huge correction there sure
so every Theory gets corrected as we
learn more
dude just be no reason to suppose that
it should be otherwise well how is this
really to the singularity why the
singular so when you hit the singularity
you know that you need some
Improvement
to Einstein's theory of gravity
and that Improvement we understand what
kind of things that Improvement should
involve it should involve quantum
mechanics Quantum effects become
important there it's a small thing
and
um
we don't understand exactly what the
theory is but we know there's no reason
to think you know Einstein's theory was
invented to describe
weekly curves things the solar system
and so on it it's incredibly robust that
we now see that it works very well near
the horizons of around black holes and
so on so
so it's a good thing
that the theory drives itself
that it predicts its own demise
Newton's gravity had its demise
there were regimes in which it wasn't
valid
Maxwell's electromagnetism had its
demise there was uh
regimes in which Quantum effects greatly
modified
the equations
but
general relativity all on its own
found drove a system which originally
was fine
would perversely wander off into a
configuration in which Einstein's
equations no longer applied so to you
the edges of the theory are wonderful
the failures the edges are wonderful
because that keeps that keeps us in
business so that one of the things you
said I think in your Ted Talk that uh
the the the fact that quantum mechanics
and uh and relativity
don't describe everything and then they
Clash is wonderful all right I forget
the adjective you used but it was
something like this so why is that uh
why is that interesting to you in that
same way that there's contradictions
that create Discovery there's no
question in my mind of course many
people would disagree with me that now
is the most
wonderful time to be a physicist so so
people people look back at at um
it's a classical thing to say
among physicists uh I wish it were 1920.
right quantum mechanics had been just
understood
uh there was the periodic table
there was but in fact that was such a
rich thing
um that
uh
well so that what a lot of exciting
stuff happened around 1920. it took it
took the whole it took a whole century
to sort out the new insights that we got
especially adding some experimental
stuff into the into the bunch actually
making observations and adding all the
experimental things all the computers
also help with visualizations and all
that kind of stuff yeah yeah yeah it was
a whole sort of Wonderful
Century I mean the seed of
general relativity
was the incompatibility
of Maxwell's Theory of the
electromagnetic field
with Newton's laws of gravity they were
incompatible because
if you look at Maxwell's Theory
there's a contradiction if anything goes
faster than the speed of light
but Newton's theory of gravity
the uh
gravitational field the gravitational
force is instantaneously transmitted
across the entire universe
so you could you know if you had a
a a a friend on you know in another
galaxy with a very sensitive
measuring device that could measure the
gravitational field that could just take
this cup of coffee and move it up and
down and Morse code and they could get
the message instantaneously over another
galaxy that leads to all kinds of
contradictions it's not it's not
self-consistent
it was exactly in resolving those
contradictions that Einstein came up
with the general theory of of
relativity and it's fascinating how this
contradiction which seems like maybe
it's kind of technical thing
led to a whole new vision of the of the
universe
now let's not get fooled because
lots of contradictions are technical
things we haven't set up the
we run into other kinds of
contradictions that are Technical and
they they don't seem to you know they
would just we understood something wrong
we made a mistake we set up our
equations in the wrong way we didn't
translate the formalisms as opposed to
revealing some deep mystery that's yet
to be uncovered yeah yeah and so we
never we're never very sure which are
which are the really important ones
but to you the difference between
quantum mechanics and general relativity
seem the the tension the contradiction
there seems to hint at some deeper
deeper thing that's going to be
discovered in the century yes because
that one has been understood since the
50s poly was the
uh first person to notice it and Hawking
in the early 70s gave it a really much
more visceral form
um and people have been
hurling themselves at it trying to
reduce it to some technicality but
nobody has succeeded and the efforts to
understand it have led to
uh all kinds of interesting relations
between Quantum systems and and
applications to other fields and and so
on well let's actually jump around so
we'll return to black holes I have a
million questions there but let's let's
go into this unification
uh the battle against the contradictions
and the tensions between the theories of
physics what is quantum gravity maybe
what is the standard model of physics
what is quantum mechanics what is
general relativity what's quantum
gravity
uh what are all the different
unification efforts
okay so again five questions yeah
it's a theory that describes
everything with astonishing accuracy
it's the most
accurate theory in the history of human
thought
Theory and experiment have been
successfully compared to 16 decimal
place
we have that stenciled on the door where
where I work you know it's a it's an
amazing it's an amazing feat of the
human mind
it describes
um the electromagnetic interaction
unifies the electromagnetic interaction
with the so-called weak interaction
which
you need some good tools to even view
the weak interaction and then there's
the strong interaction
which binds the quarks into protons
and the forces between them are mediated
by something called Yang Mills Theory
which is a a beautiful mathematical
generalization of electromagnetism
in which the analogs of the photons
and themselves carry charge
and
um so this uh the final piece of this
of the standard model everything in the
standard model has been observed and its
properties have been measured the final
particle to be observed was the Higgs
particle
served like a over a decade ago the
Higgs is already a decade ago I I think
it is yeah wow time flies but you better
check me on that yeah it's it's true but
so much fun has been happening it's so
much fun it's been happening and so
that's all
um
that's that's all pretty well understood
there's some things that miter might not
around the edges of that you know Dark
Matter neutrino masses
some sort of
fine points or things we
haven't quite measured perfectly and so
on but it's largely a very complete
uh complete Theory and we don't
expect
anything very new
conceptually
in the completion of that anything
contradictory but I'm new because can't
you think contradictory yeah I'll have
some wild questions uh for you on that
front but yeah anything that yeah
because there's no gaps it's so accurate
so precise it's predictions it's hard to
imagine something yeah yeah yeah and
it was all based on something called let
me not explain what it is let me just
throw out the buzzword
renormalizable quantum field Theory they
all fall in the category of
renormalizable quantum field Theory I'm
going to throw that at a bar later to
impress
impress the girls
good luck thank you
all right so uh they all they all fall
under that rubric gravity will not will
not will not put that suit on
so the force of gravity
Cannot Be Tamed by the same
renormalizable Quantum field Theory to
which the all the other forces
so eagerly submitted what is the effort
of quantum gravity what are the
different efforts to um
to have these two dance together
effectively to try to unify the standard
model and um
and general relativity any kind of model
of gravity
sort of the one fully
uh consistent model that we have
that reconciles
that it it would that sort of tames
gravity and reconciles it with quantum
mechanics
uh is string theory and its cousins and
we don't know what or if in any sense
String Theory describes the world the
physical world
but we do know that it
um
is a consistent
reconciliation of quantum mechanics and
general relativity and moreover one
which
um
which is able to incorporate
particles and forces like the ones we
see around us so
it hasn't been ruled out as an actual
sort of unified theory of nature
but there also isn't a
in my view some people would disagree
with me
but there isn't a reasonable uh
possibility that we would be able to do
an experiment in the foreseeable future
which would be sort of a yes or no
to to string theory okay so you've been
there from the early days of string
theory you've seen his developments what
are some interesting developments uh
what do you see as the also the future
of string theory
and what is string theory
well the basic idea which emerged in
the early 70s
was that if you uh
you take
uh the notion of a particle and you
literally
replace it by a little Loop of string
that strings are sort of softer
than than particles what do you mean by
softer
well you know if you hit a particle
if there were particle on this table a
big one and you hit it you might bruise
yourself sure
but if there was a string on the table
you would probably just push it around
and and this the source of the
infinities
in Quantum field theories that would
particles hit each other it's a little
bit of a it's a little bit of a
a jarring effect and and uh
I've never described it this way before
but it's actually scientifically
accurate but if you throw strings at
each other it's a little more friendly
one thing I can't explain is how
wonderfully precise will the mathematics
is that goes into describing String
Theory we don't just wave our hands and
throw strings around and you know
there's some very
um
compelling mathematical equations that
describe it now what was realized in the
early 70s is that if you replace
particles by strings these Infinities go
away
and you get a uh consistent
theory of gravity without
the infinities
and um
that may sound a little trivial but at
that point it already been
15 years that people had been searching
around for any kind of theory that could
do this and it was actually found kind
of
uh by accident
and there are a lot of accidental
discoveries uh in this subject
now at the same time it was believed
then that string theory was an
interesting sort of toy model
for putting quantum mechanics and
general relativity together
on paper
but
um
but that it couldn't describe some of
the very idiosyncratic phenomena
that pertain to our own Universe in
particular the form of so-called parity
violation
our another term for the bar later
tonight yeah yeah parity violation so so
if you go to the bar and I already got
the renormalizable quantity and you look
in the mirror across the bar yes the
universe that you see in the mirror is
not identical
you would be able to tell if you show
your your your your your
the lady in the bar the photograph that
shows both the mirror and you there's a
difference if she's smart enough she'll
be able to to tell which one is the real
world and which one is you now she would
have to do some very precise
measurements
and if the photograph was too grainy it
might not be possible but as Principle
as possible why is this interesting why
is it does this mean that there is some
um not perfect determinism or uh what
does that mean there's some uncertainty
no it's a very interesting feature of
the real world
that it isn't parody of invariant and
string theory it was thought could not
tolerate that
and um then it was learned in the mid
80s that not only could it tolerate that
but if you did things in the right way
you could
construct a world uh
involving strings that reconciled
quantum mechanics and general relativity
which looked more or less like the world
that
we live in
and now that isn't to say that strings
Theory predicted our world
it just meant that it was consistent
that the the hypothesis that string
theory describes our world can't be
ruled out from the get-go
and it is also
the only
proposal for a complete theory that
would describe
our world
still
nobody will believe it
until there's some kind of
direct experiment and I don't even
believe it myself sure which is a good
place to be mentally as a physicist
right always I mean Einstein didn't
believe his own uh equations right with
the black hole okay well that money was
wrong about that but
but you might be wrong too right uh so
do you think string theory is dead if
you were to bet all your money on
um no the future of strength I think
it's a
a logical error
to think that string theory is either
right or wrong or dead or alive
what it is is a stepping stone
and
uh an analogy I like to draw
is yangmil's theory
which I mentioned a few minutes ago in
the context of standard model
yangmail's theory was discovered by
Yangon Mills in the 50s
and they thought that the symmetry of
Yang and Mills
Theory
described the relationship between the
proton and the neutron that's why they
invented it
that turned out to be completely wrong
it does however
describe everything else in the standard
model
and it had a kind of inevitability you
know they had some of the right pieces
but not the other ones sure they didn't
have it quite in the right context
and it had an inevitability to it and it
eventually sort of found its place
and it's also true of Einstein's
theory of general relativity you know he
had the wrong version of it in 1914 and
he was missing some pieces and you
wouldn't say that that his early version
was right or wrong he'd understood the
equivalence principle it understood
space-time curvature he just didn't have
everything I mean technically you would
have to say it was wrong
and technically you would have to say
Yang and Mills were wrong and I guess in
that sense
I would believe just
odds are
we always keep finding new wrinkles odds
are we're going to find new wrinkles and
strings Theory and technically what we
call String Theory Now isn't quite right
but we're always going to be wrong but
hopefully a little bit less wrong every
time except exactly and I I would you
know bet the farm as they say do you
have a farm
you know I say that much more seriously
because not only do I have a farm but we
just renovated it
simply before I read it so before I
renovated better get the far my wife I
spent five years renovating it before I
you were much much looser with that
statement but now I really means
something no no it really means
something and and I would bet the farm
on the um
on the uh guess that 100 years from now
String Theory will be viewed as a
stepping stone towards a greater
understanding of of nature
and and it would I mean another thing
that I didn't mention about strings
theory is of course we knew that it
solved the Infinities problem and then
we later learned that it also solved
Hawking's puzzle about
what's inside of a black hole
and you put in one assumption you get
five things out you somehow you're doing
something right you know probably not
everything but you're you're you know
there's some good signposts and there
have been a lot of good signposts like
that
it is also mathematical toolkit and you
you've used it you've used it with
comrade Waffa uh maybe we can sneak our
way back from String Theory into black
holes yeah
um what was the idea that you and
Cameron valpha developed with the
holographic principle and string theory
were we able to discover through through
this through string theory about black
holes or um
that connects us back to the reality of
black holes yeah so that is a very
interesting story I was
interested in black holes before I was
interested in String Theory I was sort
of a reluctance
strength there is in the beginning I
thought I had to learn it because people
were talking about it but you know once
I studied it I I grew to love it first I
did it in a sort of dutiful way these
people say they've claimed quantum
gravity I ought to read their papers at
least
and then the more I read them the more
interested I got and I began to see you
know they
they phrased it in a very clumsy way the
description of string theory was was
very clumsy and mathematically clumsy or
just mathematically yeah
it was all correct but
but
mathematically clumsy but it often
happens
that in all kinds of branches of physics
that
um people start working on it really
hard and they sort of dream about it and
live it and breathe it and they begin to
see inner relationships and
they see a beauty that
is really there they're not they're not
deceived they're really seeing something
that exists but if you just kind of look
at it you know you can't you can't grasp
it all in the beginning and and um
so
our understanding of string theory in uh
uh in 1985 was almost all about uh you
know
weekly coupled waves of strings
colliding and so on we didn't know how
to describe
a big thing like a black hole and so you
know in string theory of course we could
show that strings in theory in some
limit reproduced Einstein's theory of
general relativity
and corrected it but we couldn't do any
better with black holes
than
um
before my work with command we couldn't
do any better than Einstein and tortill
had done
now
um one of the puzzles
um you know if you look at the
Hawking's headstone and also Boltzmann's
headstone and you
put them together you get a formula
for their really Central equations in
20th century physics I don't
think there are many equations that made
it to headstones
and and they're really Central equations
and you put them together and you get a
formula for the number of gigabytes in a
black hole
now a short shelves description
the black hole is literally a hole in
space and there's no place to store the
gigabytes
and it's not too hard to and this really
was wheeler and beckenstein and
wheeler beckenstein and Hawking
to come to the conclusion that
if there isn't a sense in which a black
hole can store
some large number of gigabytes
that quantum mechanics and gravity can't
be consistent
we got we got to go there a little bit
so uh so how is it possible I won't say
gigabyte say there's some information so
black holes can store information how is
this thing that sucks up all light and
it's supposed to basically be you know
be super homogeneous and boring how is
that actually able to store information
where does the store information on the
inside on the surface
uh where where's yeah and what's
information
I'm liking this ask five questions to
see which one you actually answer oh
okay I'm going to ask you about that I
should try to memorize them and answer
each one in order just to answer them I
don't know I don't know what I'm doing
I'm desperately desperately uh trying to
figure it out as I go along here so
um Einstein's Black Culture short sort
of black hole they can't store
information
this stuff stuff goes in there and it
just keeps flying and it goes to the
singularity and it's gone
however
Einstein's theory is not exact
it has Corrections
and string theory tells you what those
Corrections are
and so you should be able to find some
way of some alternate way of describing
the black hole that enables you
to understand
where the gigabytes are stored
so what Hawking and beckenstein really
did was they showed that physics is
inconsistent
unless
a black hole can store an a number of
gigabytes proportional to its area
divided by four times
Newton's constant times Planck's
Constant and that's another wild idea
you said area not volume
exactly
and that's the holographic principle the
universe is so weird and that's the
holographic principle that's called the
holographic principle that is it's the
area we're just jumping around what is
the holographic principle what does that
mean well is this some kind of weird
projection going on what what the heck
uh well I was just before I came here
writing an introduction to a paper and
the first sentence was
the
as yet imprecisely defined holographic
principle
blah blah blah so nobody knows exactly
what it is
but roughly speaking it says just what
we were alluding to that
um
really all the information
that is in some volume of space-time can
be stored on the boundary of that region
so this is not just about black holes
it's about any any areas based on any
area space however we've made sense of
the holographic principle for black
holes
we've made sense of the holographic
principle for something which could be
called anti-decider space which
could be thought of as a giant as the
black hole turned into a whole universe
and
um we don't really understand how to
talk about the holographic principle for
either flat space which we appear to
live in
or
asymptotically the sitter space which
astronomers tell us we actually live in
as the universe continues to expand
so it's one of the one of the huge
problems in uh physics is to
you know apply or even formulate the
holographic principle for
more realistic
well black holes are realistic we see
them but um
yeah in in more General context so from
a general statement of the holographic
principle what's the difference in flat
space and uh asymptotic decider space so
flat space is just an approximation of
like the world we live in so like uh uh
the sitter space at some time I wonder
what that even means meaning like
uh asymptotic over what okay so for
thousands of years
you know until the last half of the 20th
well sorry until the 20th century
um we thought space time was flat
can you elaborate on flat
or what do we mean by flat
well like the surface of this table
is is flat let me just give an intuitive
explanation surface of the table is flat
but the surface of a basketball
is curved
so the universe itself
could be flat like the surface of a
table or it could be curved like a
basketball which actually has a positive
curvature
and then there's another kind of
curvature called the negative curvature
and curvature can be even weirder
because
that kind of curvature I've just
described is the curvature of space
but Einstein taught us that we really
live in a space-time continuum
so we can have curvature in a way that
mixes up space and time
and that's kind of hard to visualize
because you have to step what a couple
of Dimensions up so it's hard to you
have to step a couple but even a
if you have flat space and it's
expanding in time
you know we could imagine we're sitting
here this room good approximation it's
flat but imagine we suddenly start
getting further and further apart then
space is flat
but it's expanding which means it's
space time is curved
automates about space time okay so
what's the what's the sitter in
anti-disitter space
the three simplest space times
are flat space time which we call
minkowski's base time
and negatively curved space-time
anti-decider space
and positively curved space-time the
sitter space
and so astronomers
um think that
on large scales even though for
thousands of years we hadn't noticed it
beginning with Hubble
we started to notice that space time was
curved space is expanding in time means
that space time is curved
and the nature of this curvature is
affected by the matter in it
because matter itself
causes the curvature of space-time
but as it expands the matter gets more
and more diluted
and one might ask when it's all diluted
away
is space-time still curved
and astronomers believe they've done
precise enough measurements to determine
this
and they believe that the answer is yes
the universe is now expanding eventually
all the unit matter in it will be
expanded away but it will continue to
expand
because uh well they would call it the
dark energy Einstein would call it a
cosmological constant in any case that
the in the far future
matter will be expanded away and we'll
be left with empty decider space okay so
there's this cosmological Einstein's
cosmological constant that now hides
this thing that we don't understand
called Dark Energy what's dark energy
what's your best guess at what this
thing is
why do we think it's there
it's because of this it comes from the
astronomers
dark energy is synonymous with positive
cosmological constant
and um
uh we think it's there
because the astronomers have told us
it's there
and
um they they know what they're doing and
we don't know really really hard
measurement but they know they really
know what they're doing
and
we have no freaking idea why it's there
another big mystery another another
reason it's fun to be a physicist and if
it is there why should it be so small
why should there be so little why should
it have hit itself from us
why shouldn't there enough be enough of
it to substantially cons curve the space
between us and the moon why did there
have to be such a
small amount that only the crazy best
astronomers in the world could find it
well again the same thing be said about
all all the constants
all of the content be said about gravity
can't they be said about the speed of
light
like why is the speed of light so slow
so fast so slow
relative to the size of the universe
can't it be faster
or no well the speed of Lights is a
funny one because you could always
choose units
in which the speed of light is one you
know we measure it in kilometers per
second and it's 100
86 000 or miles per second is 186 000
miles per second
and but if we had used different units
yeah then we could make it one but you
can make dimensionless ratios
so
um you know you could say why is the
time scale set by the expansion of the
universe so large compared to the time
scale of a human life or so large
compared to the time scale for a neutron
to Decay you know yeah I mean ultimately
you know the reference the temporal
reference frame here is a human life
maybe isn't that the important thing for
us uh descendants of Apes isn't that a
really important aspect of physics
like uh because we kind of experienced
the world we Intuit the World Through
The Eyes of
the these biological organisms I guess
mathematics helps you escape that for a
time but ultimately isn't that
how you wonder about the world
absolutely that like a human life yeah
time is only 100 years because if you
think of everything
um if you're able to think in I don't
know in billions of years
uh then maybe everything looks way
different
maybe universes are born and die and
maybe all these physical phenomena
become much more intuitive that we see
at the Grand scale of general relativity
well that is one of the a little off the
track here but that certainly is one of
the nice things about being a physicist
it's
you spend a lot of time thinking about
you know insides of black holes and
billions of years in the future and and
it's sort of uh
gets you away from the day-to-day uh
into into another fantastic
realm
um
but I was answering your question about
how there could be information in a
black hole yes
so
Einstein only gave us
an approximate description and we now
have a theory that corrects it string
theory
and now sort of was the Moment of Truth
well when we first discovered String
Theory we knew we knew from the get-go
that string theory would correct what
Einstein said
just like Einstein corrected what Newton
said
um but we didn't understand it well
enough
to actually compute the correction to
compute how many gigabytes there were
and sometime in the early 90s
we began to understand the mathematics
of string theory better and better
and it came to the point where it was
clear that this was something we might
be able to compute
and it was a kind of Moment of Truth for
string theory because
if it hadn't given the answer
that beckenstein and Hawking said it had
to give for consistency
String Theory itself would have
been inconsistent and we wouldn't be
doing this interview well
that's a very dramatic statement but yes
uh that's not the most that's not the
most dramatic thing
I mean but like okay that's very life
and death you mean like that that uh
because string theory was Central to
your work at that time is that what you
mean well String Theory would have been
inconsistent yeah okay so that would be
a string theory would have been
inconsistent but those inconsistencies
can give birth to other theories like
you said the inconsistency right
something else could have happened yes
yeah it would have been a major a major
uh change in the way we think about
string theory if it and it was a good
thing that you know one supposition that
the world is made of strings solves two
problems not not one solves the infinity
problem and it solved the Hawking's
problem
and also the way that it did it
was very uh was very beautiful
um it it gave an alternate description
so
alternate description thing of things
are are uh
are very common I mean we could to take
a simple example this bottle of water
here is
90 percent full I could say it's 90 full
I could also say it's ten percent empty
those are obviously the same statement
and they're it's trivial to see that
they're the same but there are many
statements that can be made in
mathematics and mathematical physics
that are equivalent
but might take years to understand that
they're equivalent
and might take the invention or
discovery of whole new fields of
mathematics to prove their equivalent
and this was one of those
we found an alternate description
of the certain black holes and string
theory
which we could prove was equivalent and
it was a description of the black hole
as a hologram
that can be thought of a holographic
plate
that could be thought of as sitting on
the surface of the black hole
and the interior of the black hole
itself sort of arises as a projection
uh or the near Horizon region of the
black hole arises as a projection
of that holographic plate so the two
descriptions were the hologram
the three-dimensional image and the
holographic plate
and the whole gram is what Einstein
discovered in the holographic plate
is what we discovered
and this idea that you could describe
things very very concretely in string
theory in these two different languages
of course took off and was applied to
many uh many different
many different contexts within string
string theory so you mentioned the
infinity problem in the Hawking problem
uh witch-hawking problem the the that
the black hole destroys information or
that the what which Hawking problem are
we talking about well there's really two
Hawking problems they're very closely
related
one is how does the black hole store the
information
and
um
that is the one that we
solved in some cases so it's sort of
like you know your your smartphone
how does it store at 64 gigabytes well
you rip the cover off and you count the
chips and there's 64 of them each with a
gigabyte and you know they're 64
gigabytes
but that does not solve the problem of
how you get information in and out of
your smartphone
you have to understand a lot more about
the Wi-Fi and the internet and the
cellular and and that's where Hawking
radiation this prediction it starts
that's where Hawking radiation comes in
and that problem of how the information
gets in and out you can't you couldn't
have explained how information gets in
and out of an iPhone without first
explaining
how it's stored in the first place so
just to clarify the storage is on the
plate
on the flight on the holographic plate
and then it projects somehow inside the
the bulk the the space time is the
Hologram the Hologram but man I mean did
you have any intuitive when you sit late
at night and you stare at the stars do
you have any intuitive understanding
what a holographic plate is
um like that there's two Dimension no
projections that store information
how a black hole
could store information on a holographic
plate
I think we do understand in in great
mathematical detail and also intuitively
and it's very much like an ordinary
hologram or you hold up a holographic
plate and you sh it contains all the
information you shine a light through it
and you get an image which looks
three-dimensional yeah but why should
there be a holographic plate
why should there be yeah why
that is the Great thing about being a
theoretical physicist is
anybody can very quickly stump you if
they going to the next level of wise
yeah so if I can just keep asking yeah
you could just keep asking and it won't
take you very long to
so the trick in being a theory a
theoretical physics is finding the
questions that
you can answer sure so so the questions
that we think we might be able to answer
now and we've partially answered
is that
um there is a holographic explanation
for certain
kinds of things and string theory Sure
we've answered that
now we'd like to take what we've learned
and that's what I've mostly been doing
for the last 15
20 years I haven't really been working
so much on string theory proper I've
been sort of taking the lessons that you
we learned in string theory
and trying to apply them to the real
world
using only
assuming only what we know for sure
about the real world so on this uh topic
you you co-wrote co-author the paper
with Stephen Hawking called soft hair on
black holes yes that makes the argument
against Hawking's original prediction
that black holes destroy information can
you explain this paper
yeah and the title yeah
okay so um first of all
um
the hair on black holes
is a word that was coined by the
greatest phrase master in the history of
physics John Wheeler invented the word
black hole
and he also said that uh he made the
statement that black holes have no hair
that is every black hole in the universe
is described just by its mass and spin
they wrote they can also rotate as was
later shown by Kerr
and
um
and this is very much unlike a star
right every Star of the same mass is
different
in a multitude of different ways
different chemical compositions
different motions of the individual
molecules every star in the universe
even of the same mass is different in
many many different ways
black holes are all the same
and that means when you throw some in
Einstein's description of them
which we think must be corrected
and um
if you throw something into a black hole
it gets sucked in
and if you uh throw in a red book or a
Blue Book
the black hole gets a little bigger but
there's no way within Einstein's theory
of telling how they're different
and that was one of the assumptions
that Hawking made in his
1974-75 papers in which he concluded
that black holes destroy information you
can throw encyclopedias thesis defenses
the Library of Congress it doesn't
matter it's going to behave exactly the
same uniform way yeah so what what
Hawking and I showed and also Malcolm
Perry
um
is that one has to be very careful about
what happens
at the boundary of the black hole
and this gets back to something I
mentioned earlier about when two things
which are related by a coordinate
transformation are and are not
equivalent
and
um
and what we showed is that they're very
subtle imprints when you throw something
into a black hole
they're very subtle imprints left on the
horizon of the black hole which you can
read off at least partially what went in
and
um so this
invalidates uh Steven's original
uh argument that the information is
destroyed and that's a soft hair that's
the soft hair right so and soft is the
word that is used in physics for things
which have very low energy and these
things actually carry no energy
there are things in the universe which
carry no energy
you said I think to Sean Carroll
um by the way everyone should go check
out Sean Carroll's mindscape podcast
it's incredible and Sean Carroll is an
incredible person I think he said there
maybe in a paper I have a quote you said
that a soft particle is a particle
that has zero energy just like you said
now and when the energy goes to zero
because the energy is proportional to
the wave of length it's also spread over
an infinitely large distance if you like
it's spread over the whole universe
it somehow runs off to the boundary what
we learned from that is that if you add
a zero energy particle to the vacuum you
get a new state and so there are
infinitely many vacuole
plural for vacuum which can be thought
of as being different from one another
by the addition of soft photons or soft
gravitons right can you uh elaborate on
this wild idea
if you like it spreads over the whole
universe when the energy goes to zero
because the energy is proportional to
the wavelength it also spreads over an
infinitely large distance if you like
it's spread over the whole unit it's
spread over the whole universe what
um can you explain these soft gravitons
and photons
yeah so the soft gravitons and photons
um have been uh known about since the
60s
but exactly what we're supposed to do
with them or how we're supposed to think
about them
um I think what has been
well understood
only recently
and in quantum mechanics the energy of a
particle
is proportional to Planck's constant
times its wavelength
so when the energy goes to zero the
wavelength gets goes to Infinity
now if something has
uh zero energy and it's spread all over
the universe
in what sense is it actually there
that's yeah that's been the confusing
thing
to make a precise statement about when
something is and isn't there
now the simplest way of seeing
so people might have taken the point of
view
that if it has zero energy and is spread
all over the universe it's not there we
can ignore it
um but if you do this you'll get into
trouble
and one of the ways that you'll get into
trouble is that even though it has zero
energy it doesn't have zero angular
momentum
if it's a photon it always has angular
momentum one if it's a graviton it's uh
angular momentum two
so you can't say that the state of the
system with the Zero Energy Photon
should be identified with the one
without the Zero Energy Photon that we
can just ignore them because then you
will conclude that angular momentum is
not conserved
and the angular momentum is not
conserved things won't be consistent
and
um and of course you can have a lot of
these things and typically you do get a
lot of them
and when you you can actually do a
calculation that shows that every time
you scatter
two particles you create an infinite
number of them infinite number of the
soft photons the Zero Energy ones yeah
and so these are and they're somehow
everywhere but they're everywhere but
they're also contained information or
they're able to store information and
they're able to store information
they're able to store an arbitrary large
amount of information
so what we pointed out is
so what these things really do one way
of thinking of them is they rush off to
the edges of the universe
spreading out all over the space is like
saying they rush off to the energy edge
of the universe right
and that includes if the interior of the
black hole is not considered part of the
universe that includes the edge of the
black hole
so we need to set up our description of
physics
so that all the things that are
conserved
are still conserved in the way that
we're describing them and that will not
be true if we ignore these things we
have to keep careful track of these
things
and people had been sloppy about that
that and we learned how to be very
precise and careful about it and this
and once you're being precise you can
actually uh that makes you can actually
answer this kind of very problematic
thing that Hawking suggested that black
holes destroy information well what we
showed
is that there's an error in the argument
that all black holes are the same
because they hadn't kept track of these
uh these very subtle things
and
um whether or not
this is the key error in the argument
remains to be seen or whether this is a
technical Point yes but it is an error
it is an error and uh Hawking obviously
agreed with it Hawking agreed with it
and he was sure that this was the he was
sure that this was this was a critical
error that this was the critical error
in that understanding this would would
would get us the whole story and and and
and and that could well be what was it
like working with Stephen Hawking on
this particular uh problem because it's
kind of a whole journey right well you
know I I I I love the guy I he's so
passionate about
physics
uh he just
yeah his
his Oneness with
the problem and uh I mean it's
so his mind is all occupied by the world
that's uh yeah and let me tell you
there's a lot of other things with his
illness and with his celebrity and yeah
a lot of other things
a lot of distractions pulling it is uh
at his mind he's still there that's
right I remember him turning down
tea with Lady Gaga so we could spend
another hour on our paper
that my friend's dedication what did you
learn about physics what did you learn
about life uh from uh having worked with
Stephen Hawking well he was one of my
great teachers of course he's he's older
than me and I was I was reading his um
his textbooks in in um
in graduate school and um
uh you know I learned a lot about uh
relativity from him I learned about
passion for a problem I I learned about
um
not caring what other
people think you know I mean physics
isn't
interesting culture even if you make a
great discovery
like Walking Dead
people don't believe everything you say
in fact people love to disagree
it's it's a it's a a culture that uh
cherishes disagreement and and so you
know he kept ahead with what he believed
in and sometimes he was right and
sometimes he was wrong do you feel
pressure from the community so for
example with strength Theory
I was very popular for a time there's a
bit of criticism or is less popular now
do you feel the forces of the community
as it moves in and out of different
fields or do you try to stay like how
difficult is it to stay uh
intellectually and mathematically
independent from the community
personally
uh I'm lucky
I'm well equipped for that
I when I
started out in graduate school the
problem of quantum gravity was
not considered interesting
he still did it anyway I still did it
anyway I I'm a little bit of a
contrarian I guess and I think that has
served me well
um
and uh
people are always sort of disagreeing
with me
and they're usually right but I'm right
enough and like you said the
contradiction ultimately paves the path
of Discovery yeah uh let me ask you just
on this tension we've been dancing
between physics and Mathematics
um what to you is an interesting line
you can draw between the two uh you have
done some very complicated mathematics
in your life to explore the laws of
nature what's the difference between
physics and Mathematics
to you well um
I love math I think my first love is is
physics and the math that I've done I've
I've done to because it was needed and
serve as a physics in service of physics
but then of course in the
In the Heat of it it has its own appeal
and uh In the Heat of it I like it sure
it has its its own appeal and I
certainly enjoyed it and
ultimately I would like to think I
wouldn't say I believe
but I would like like to think that
there's no difference between physics
and Mathematics that
or mathematics
is realized in the physical world and
all physics has a for a mathematical
basis that they're really the same thing
I mean why would there be math that had
no physical
manifestation it seems a little odd
right you have two kinds of math some
that
are relevant to the real world where
they don't have to be contradictory but
you can have a can't you not have
mathematical objects that are not at all
connected to the physical world so I
mean this is to the question of is math
discovered or invented
I said to you math is just discovered
and and and there's a deep linkage
between the two yeah yeah yeah do you
find it all compelling these ideas uh
like something like Max tag Mark where
our universe is actually fundamentally a
mathematical object
that math is our universe is
mathematical fundamentally mathematical
in nature
my expertise is a a physicist doesn't
add anything to that
it's not really you know physics is
you know I was once very interested in
philosophy and
you know physics
physics
I like questions that can be answered
that it's not obvious what the answer is
and that you can find a
an answer to the question
and everybody will agree
what the answer is and that there's a an
algorithm for for getting there
um not that these other questions aren't
interesting
um and they don't somehow have a way of
preventing presenting themselves but to
me the interesting thing is to
is is motion in what we know is learning
more and understanding things that we
didn't understanding before things that
seemed totally confusing having them
seem obvious that's wonderful so
I think that's those questions are there
I mean I would
even go further you know the whole
Multiverse I don't
I don't think there's too much we
concrete we're ever going to be able to
say about it this this is fascinating
because you spend so much time in string
theory which is devoid from a connection
to the physical world for a long time
like it did not devoid but it it travels
in a mathematical world that seems to be
beautiful and consistent and seems to
indicate uh that it could be a a good
model of the laws of nature but there's
it's still traveling independently
because it's very difficult to
experimentally verify but there's a
promise with Laden in it in the same way
Multiverse or uh you can have a lot of
kind of very far out there questions or
your gut and Instinct and intuition says
that maybe in 1500 200 years you'll be
able to actually have strong
experimental validation
right
I think that with string theory
um
I don't think it's likely that we could
measure it
but we could get lucky
in other words just to take an example
about 10 or 20 years ago it was thought
that they had seen a string in the sky
in it that it was seen by
um
you know uh doubled stars that were
gravitationally lensed around the
gravitational field produced by some
long string there was a line of double
instant now the signal went away okay
but
people were hoping that they'd seen a
string and it could be a fundamental
string that it somehow gotten stretched
and that would be some evidence for
string theory there was also bicep two
which
it was a the experiment was wrong
but it could have happened
it could have happened that we got lucky
and this experiment was able to make
direct measurements
certainly would have been measurements
of quantum gravity if not string theory
so it's a logical it's a very logical
possibility that we could get
experimental evidence from string that
is a very different thing than saying do
this experiment here's a billion dollars
and after you do it we'll know whether
or not strings are real
but I think it's a crucial difference
it's measurable in principle
and we don't see how to get
from here to there
if we see how to get from here to there
in my eyes it's boring
right so when I was a graduate student
they knew how to measure the Higgs boson
took 40 years
but
they did it
I not just say that stuff is boring I
don't want to say that stuff yeah but I
I you know you know would Magellan set
out
he didn't know we could get around the
world
there was no map you know so I don't
know how we're gonna
um
connect in a concrete way
um all these ideas of string theory to
the real world and you know when I
started out in graduate school I said
what is the what is the most interesting
problem
that there might be the deepest most
interesting problem that there might be
progress on in 60 years
and
I think it could be you know uh that you
know in another 30 years that maybe
we'll learn that uh we have understood
how black holes store information you
know that doesn't seem wild that that
we're able to abstract what we learned
from string theory and show that it's
operative and and and and and you know I
mean the Bose Einstein condensate they
did you know they if you win Bose and
Einstein
uh predicted it when was that the 30s
maybe early 30s
it took they were there were 20 orders
of magnitude that were needed
in order to Improvement in order to
measure it
um and they did 50 years later
so and then you couldn't have guessed
how that had happened how they could
have gotten that
and it could happen that we I don't
think we're gonna light
see the heterotic string Spectrum in an
accelerator but but it could be that
things come around and and uh
in an interesting way and
somehow it comes together and the fact
that we can't see to the end
isn't a reason not to do it you know we
just you know what did they do when they
were trying to find the Pacific right
they just they took every route they
just tried everything and that's what
we're doing and we're taking and I'm
taking the one that my nose tells me is
the best you know and other people are
taking other ones and that's good
because we need every
person taking every route
and you know if somebody on another
route uh
uh find something that looks really
promising you know I'm gonna make a
Portage over the mountain and get on
their street you know so the fact that
you don't
see the experiment Now isn't to me a
reason to give up on what I view as the
most fundamental
Paradox in 20th century
20th in present physics 20 21st century
physics absolutely you can see that it's
possible you just don't know the way but
that's what I mean why some of the
philosophical questions could be
formulated in a way that's explorable
scientifically so uh some of the stuff
we've talked about but you know for
example this topic that's become more
okay to talk about which is the topic of
consciousness
uh you know to me as an artificial
intelligence person that's a very
practically interesting topic but
there's also philosophers uh Sean
Carroll loves to argue against them but
there's the philosophers that are pen
psychist I'm not against philosophers
it's just not as fun I don't it's not a
fun right
but they they uh they start a little
flame of a fire going that some of those
Flames I think eventually become physics
So eventually it becomes something that
we can really like having them around is
really important because you'll discover
something by modeling and exploring
black holes it's really weird and having
these ideas around like the ideas of pan
psychists that Consciousness could be a
fundamental force of nature just even
having that crazy idea swimming around
in the background could really spark
something where
that you were missing something
completely
and it's just that's where the
philosophy done right I think is very
useful that's where even the you know
these thought experiments which is very
fun and sort of the the tech sci-fi
world that we live in a simulation uh
that you know taking a perspective of
the universe as a as a computer as a as
a computational system that process
information which is a pretty intuitive
notion but you can just even reframing
it that way for yourself could really
open up some different way of thinking
and then you have
I don't know if you're familiar with
Stephen wolfram's work of like cellular
atom and complexity yeah I did a podcast
with Stephen Hey Stephen that's awesome
I I to me forget physics to get all that
uh cellular automata
make no sense they're so beautiful
they're so like they're from simple
rules you can create complexity I I just
don't think you know he wrote a book A
New Kind of Science
um
basically hinting at which a lot of
people offended as like we don't have a
good way to talk about these objects we
don't we can't figure out what is
happening here these simple these
trivial rules can create incredible
complexity all right he's totally right
about that yeah
and I and physicists I guess don't have
don't know what to do with that
don't know do with cellular automata
because you can describe the simple
rules that will govern the system but
how complexity can emerge like
incredible complexity yeah
of course wolfram's version of that is
that physicists will never be able to
describe it right yeah exactly he tries
to prove that it's impossible what do
you make of that what do you what do you
uh what do you make about the tension of
being a physicist and potentially not
being able to it's like a Freud or
somebody that maybe uh Sigmund Freud
maybe you'll never be able to actually
describe the human psyche
uh is that a possibility for you that
you will never be able to get to the
core fundamental description of the laws
of nature
yeah so I had this conversation with
Weinberg
yeah how'd it go
so Weinberg has this book called dreams
of a final Theory yeah
and I had this conversation with him I
said
why do you think
um there's ever going to be a final
Theory why should there ever be a final
Theory I mean what does that mean do
physics departments shut down we've
solved everything
um and you know what is it doesn't it
seem that every time we answer some old
questions we'll
we'll just find new ones and that will
just keep going on forever and ever
he said well
that's what they used to say about the
Nile they were never going to find the
end
and one day they found it yeah so I
don't I don't know
um String Theory doesn't
String Theory doesn't look like a
candidate to me for a final Theory it
as it stands now it doesn't get to the
bottom of the world
yeah it seems to me that even if we kind
of solved it and we've
did experiments there still would be
more questions like why are there four
dimensions instead of six it doesn't
seem to have any anything that in it
that would explain that you could you
can always hope you know that there's
something that we don't know about
string theory that we'll explain it but
but it but it still doesn't look like
it's going to answer every question
and um
why is there one time not two you know
why is this but you know it doesn't seem
like it's
I don't even know what it would mean to
answer every question but to answer
every question obviously so when you
refer to The Theory of Everything
you'll be able to have a
if it exists
it would be a theory that allows you to
predict precisely the the behavior of
objects in the universe and their their
movement right what what about them
their movement
yeah like like precisely no matter the
option right that's true so so that
would be a really interesting State of
Affairs
if we could predict everything
but not necessarily understand
everything
so for example
let's just forget about gravity I mean
we're not too far from that situation if
we forget about gravity the standard
model
in principle given a big enough computer
predicts almost everything
but
if you look at the standard model it's
kind of a laundry list with neutrino
masses and all that stuff they're
they're hundreds of free parameters
where do they come from
is there an organizing principle
is there some further unification sure
so so being able to predict
uh everything is not the only goal that
physicists have
so on the way to trying to predict
you're trying to understand that's
actually probably the goal is to
understand yeah
but but but right we're more interested
in understanding than actually
than actually doing the predictions but
the predictions are more
focusing on how to make predictions is a
good way to improve your understanding
because you know you've understood it if
you could do the predictions yeah one of
the interesting
things that might come to a head with is
our artificial intelligence there's an
increasing use of AI in in physics we
might live in a world where AI would be
able to predict perfectly what's
happening and so that will as physicists
you'll have to come to to the fact that
you're actually not that interested in
prediction
I mean it's very useful but you're
interested in really understanding the
Deep laws of nature versus a perfect
predictor yeah like uh you want to play
Just within AI yeah AI people are trying
to understand
what it is that the AI Bots have learned
in order to
produce whatever they produce for sure
but you still don't understand deeply
especially because they're getting
you know uh especially language models
if you're paying attention uh the
systems that are able to generate tax
they're able to have conversations chat
gpts the recent manifestation of that
there they just seem to know everything
they're trained on the internet they
seem to be very very good at uh
something that looks like reasoning
they're able to generate uh you can ask
them questions they can answer questions
it just feels like this thing is
intelligent right uh and I could just
see that being possible with physics you
ask any kind of physical question and
it'll be able to very precise about a
particular star system or a particular
black hole you'll say well these are the
numbers it's it'll perfectly predict
and then sure you can understand
uh how the neural network is the
architecture is structured actually for
most of them now they're very simple you
can understand what data is trained on
huge amount of data you're giving a huge
amount of data from a very nice
telescope or something
and then but it seems to predict
everything perfectly you know how a
banana Falls when you throw it like
everything is perfectly predicted you
still don't have a deep understanding of
what governs the whole thing
um
and maybe you can ask it a question
it'll be some kind of Hitchhiker's Guide
to the Galaxy type answer uh that you
know it's a funny world uh we live in of
course it's also possible that there's
no such deep simple governing laws of
nature
behind the whole thing I mean you
there's something in US humans it's
possible that wants it there to be yeah
it doesn't have to be right right I do
what's where do you again you're betting
the you already bet the farm but if you
were to have a second Farm
do you think there is a theory of
everything that we might get at so
um simple laws in the whole thing
I don't I don't
I I honestly I I don't know but I'm
pretty confident that if there is
we won't get to it in my lifetime
I don't think we're near it but doesn't
it feel like they're like the fact that
we have the laws we do they're
relatively simple already
that's kind of incredible it's just
there seems to be there seems to be
simple laws that govern things right by
Theory of Everything you mean Theory a
theory of
of everything an algorithm to predict
everything
but a simple algorithm
a relatively simple algorithm to predict
everything
so for me it would be a sad day
if we arrived at that
without answering some deeper questions
sure of course it definitely is but the
question yes
but one of the questions before we
arrive there we're going to ask does
such a destination even exist so because
the asking the question and the possible
answers and the process of trying to
answer that question is in itself super
interesting is that is is it is even
possible to get there well there's an
equals mc squared type of there's a
function okay you can have many
parameters but
a finite number parameter function that
can predict a lot of things about our
universe well okay but just to sort of
throw one thing in in order to answer
every question
we would need a theory of the origin of
the universe right
and that is a huge
uh task right so and the fact that the
Universe seems to have a beginning
defies everything we know and love right
because we we you know one of the one of
the
basic principles the physics is
determinism that the past follows from
the
the present follows from the past
the future follows from the present so
on
but
if you have the origin of the universe
if you have a big bang that means before
that there was nothing
and you can't have a theory in which
something Falls from nothing
so somehow sounds like you don't like
singularities
well I thought for somebody that works
with black holes you'll get used to them
by now no no I I like this because it's
it's so hard to understand
I like it because it's hard to
understand but but it's really
challenging us it's not a I don't think
we're close to solving that problem so
even uh
and strength string theory has basically
had nothing there's been almost nothing
interesting said about that
in the last
many decades so String Theory hasn't
really looked at the big bang it hasn't
really tried to get to see the origin
not not successfully not not in there
there aren't compelling papers that lots
of people have read that that people
have taken it up and tried to go at it
but but there aren't there aren't there
aren't compelling
String Theory doesn't seem to
have a trick that
that helps us with that puzzle do you
think we'll be able to sneak up to the
the origin of the universe like reverse
engineer it from experimental from
theoretical perspective like okay if if
we can well it's what would be you've
already gotten yourself in trouble you
see because you use the word reverse
engineer
so if you're going to reverse engineer
that means you know you you
forward engineering means that you take
the present and determine the future
reverse engineering means that you take
the present and determine the past but
estimate the best but yes sure but but
but if the past was nothing how are you
ever gonna reverse engineer to nothing
well that's hard to do run up against
the nothing right until they have
mathematical models that break down
nicely to where you can actually start
to infer things
let's work on it no but do you think
that that it could maybe but it is
people try to do things like that yeah
but have not succeeded it's not it's not
something that we we you know we're
getting a pluses in sure
let's pretend we live in a world where
in a hundred years we have an answer to
that
yeah what would that answer look like
who what department is that from
What fields left led us there what uh uh
not what feels what set of ideas and
theoretical physics
um is it experimental is it theoretical
like what can you imagine possibly could
have possibly lead us there is it
through gravitational waves and some
kind of observations there is it
investigation of black holes is a
simulation of universes is it uh
maybe you start creating black holes
somehow I don't I don't know uh
maybe some kind of high energy physics
type of experiments
well
I have some late night ideas about that
that aren't really ready for Prime drugs
okay sure but you have some ideas yeah
yeah but but
um and many people do it could be that
some of the advances in Quantum
information Theory are important in in
that they
kind of go beyond taking Quantum systems
and just replicating themselves but
combining them with others do you think
since uh you highlighted the issue with
time and the origin of the universe do
you think time is fundamental or or
emergent
I think ultimately it has to be emergent
yeah what does it mean for time to be
emergent
well
because let's review what it means for
space to be emergent
yes what it means for space to be
emergent is that
um
you you have a holographic plate
and you shine some light that's moving
in space
and it produces an image
which contains an extra spatial
dimension
and time just goes along for the ride
so what we'd like to
do and indeed there is some rather
concrete
work in this direction though again I
would say even within our stringy
Community we're not getting a pluses on
these efforts
but what we'd like to do is to see
um
examples in which the extra space-time
dimension
is time in other words
usually what what we understand very
well mathematically is how to take
systems
uh
in
some number of space-time dimensions
and rewrite them as a plate in fewer
space dimensions
what we'd like to do is to take systems
with
one time and some number of space
dimensions and to rewrite them is a
system that had only space dimensions in
it had no time evolution
and there's some fairly concrete ideas
about how to do that but they're not
you know you universally accepted even
within the
stringy community
but isn't it wild to you yes for to be
emergent how do we Intuit
these kinds of ideas as human beings for
whom space and time seems as fundamental
as apples and oranges both Illusions
okay they're both illusions even time
you co-authored a paper titled Photon
rings around warped black holes first of
all whoever writes your paper titles
you like uh the soft hair and the and
and the term black hole in the Big Bang
you're very good at coming up with
titles yourself anyway you co-authored a
paper title Photon rings around warped
black holes in it you write quote recent
work has identified a number of emergent
symmetries related to the intricate
self-similar structure of the photon
ring so what are Photon Rings what are
some interesting characteristics of a
photon ring
um so that was a paper with Dan coppets
and Alex lipska that just came out
and this is uh paper is kind of a
wonderful example
of what happens
when you start to talk to people who are
you know way out of your comfort zone of
those different stuff and look at the
world a different way and
and some two or three years ago
um I'm I'm part of this uh
the black hole initiative I'm also part
of this event horizon telescope
collaboration that took the famous uh
though I had nothing to do with the
experiment but uh that that took the
famous picture of the of the Donut of of
m87 and
um
through conversations with them
which started out in an effort
to understand the image that they'd seen
so it's a great thing for somebody like
me a theoretical physicist
lost
seemingly lost in string land
to be presented with an actual picture
of a black hole and ask and to be yes to
be asked what can we learn from this
so you know with some help uh uh from uh
you know Michael Johnson
um and a bunch of other people
venturized in collaboration
we came up with a fantastic beautiful
answer using Einstein's theory
that is both shaping the future
of now it is shaping the future of
improved photo black hole photographs
what do you want to concentrate on in
the photograph you know just point at
the sky and click no you don't do that
you you optimize for various features
and um it's it's both shaping that and
in the process of
talking to them and thinking about how
light behaves around a black hole
it they black holes just have so many
magic tricks and they do so many weird
things
and the photon ring is among the
weirdest of them we understood the this
Photon ring and in the process of this
we said hey this Photon ring
has got to be telling us something
about the puzzle
of where the holographic plate is
um outside of a ordinary astrophysical
black hole and we nailed it for the
stringy black holes
but they have a somewhat different
character with a stringy black hole the
the black holes that describe us the
black holes that are contained in string
theory and they have different structure
in them sure well basically can we step
back so what was the light in the image
taken in 2019 not taken to 2018
um uh presented in 2000 so here's the
puzzle
um what they really saw
so the black holes tend to gather stuff
that swirls around it
yeah
and they don't know what that stuff is
made of they don't know what its
temperature is they don't know what kind
of magnetic fields there are around
there
so
the form of the image has a lot of
unknowns in it that it's dependent on
many other things other than the
geometry of the black hole
so most of what you're learning
is about the stuff
now the stuff the swirling stuff the hot
swirling stuff
is interesting as hell
but it's not as interesting as the black
hole which are the which are the most in
my view
the most interesting things of the
universe so you don't want to just learn
about the stuff you want to learn about
the black hole that that it's swirling
around so one of the
at the very first step of the very
primitive level this is just a big leap
for human civilization to be able to see
a black hole and the way you can see it
is because there's stuff around it but
you don't get to learn much about the
black hole you get to learn more about
the stuff just from the image yeah okay
but you're not going to learn about the
details before you've even seen it
because there's too many parameters
there's too many variables that govern
the stuff yeah so then we found a very
wonderful way
to learn about the black hole and here's
how it works
a black hole is a mirror
and the way it's a mirror is if light a
photon bounces off your face
towards the black hole it goes straight
to the black hole just Falls in you
never see it again
but if it just misses the black hole
it'll swing around the back and come
back to you
and you see yourself
from the photon that went around the
back of the black hole
but not only can that happen
the black hole the photon can swing
around twice
and come back so you actually see an
infinite number of copies
of yourself like with a little bit of a
delay
with a little bit of a delay right
this is awesome yeah and in fact I mean
we're not used to an object that bends
light like that right yeah so you're
gonna get some trippier effects and in
fact one of my my students has made a
really awesome computer animation of
this which I'm going to show at a public
lecture in a couple weeks where the
audience will see infinitely many copies
of themselves
so
if you so it's a black hole is like a
Hall of Mirrors you know like a
department store where you go and
there's there's the three mirrors and
you see infinitely many copies of
yourself yeah
think of the black hole as the mirror
you know and you know you go in there
with your clothes if you want to know
about your clothes you just look at the
direct image you're not learning
anything about the configuration of
mirrors
but the relation
of of
um
the image you see in front of you
to the one you see at the side and the
next one and then so on
depends only on the mirrors it doesn't
matter what clothes you're wearing
so you can go there a thousand times
wearing different clothes but each time
there will be the same relation between
the subsequent images
and that is how
we're going to learn about the black
holes
we're going to take the stuff that is
swirling around
and we're going to tease out the
subsequent images and look at their
relation
and there's some very beautiful
really beautiful mathematics which we
were surprised to realize with the
volumes and volumes of
papers on black holes in their
properties this particular
because it was a physical question that
had never been asked in exactly this way
so basically you're looking at the the
relationship with the subsequent images
the relationship but those are
ultimately formed by photons that are
swirling around the photons that are
orbiting so the photon ring are the
photons that orbit around and Beyond so
like orbit and lose orbit like they are
they yeah like so
uh wow and that starts to give you what
can you possibly figure out
mathematically about the black hole can
you the geometry of it does this
geometry the spin
um and you can verify
things behaving you know we have never
seen
a region of space-time
with such high curvature I mean yeah the
region around a black hole is crazy it's
not like in this room right the
curvature is everything you know you
spend probably enough time with the math
and the photons
can you
put yourself in that space so we're like
having a conversation pretty peaceful
comfortable flat space are you able to
put yourself in in a place around a
black hole yeah I'm able to imagine that
kind of thing yeah so for example and
actually there's a wonderful movie
um
Interstellar yeah and
um
in that movie you know Kip Thorne of
course is a great
theoretical physicist experimental who
later won the Nobel Prize
um for ligo and
that movie is very accurate
scientifically
and there's some funny statements in
there
that
of the
you know 100 million people who saw that
movie there can't be more than 10 or 20
understood
about why Matthew McConaughey is
ejecting the trash in a certain
direction in order to
but you know for example if I wear a
spinning black hole right here if I was
spinning fast enough
you wouldn't be able to stay still there
you'd be have to be orbiting around like
that you know you'd have to have your
microphone on them but I wonder what the
experiences with the actual experience
because I mean space itself is curved
well space gets very curved you get
crushed
you know my body gets ripped apart
because the forces are different on
different parts sure okay so that would
be but if but if it can be less curved
so that the curvature is very noticeable
but you're not ripped apart
the fact that this was just nonchalantly
stated is is just beautiful like two
biological systems discussing uh which
level of curvature is required to rip
apart said biological system very well
um so you propose in the paper that a
photon ring of a warped black hole is
indeed part of the black hole hologram
a photon ring of a warped black hole is
indeed part of the black hole hologram
uh so what can you Intuit about the
hologram
and the the holographic plate
from looking at the photon rings
well this paper
is exploring a new idea it's not making
it's not
it's it's not making a new
Discovery so to speak it's exploring an
idea and and and
um the ins and outs of it and and what
might work and
and what might not and this Photon ring
somehow everybody always thought that
the holographic plate sat at the Horizon
of the black hole right
and that the quantum system that
describes the black hole is inside the
horizon
and it in fact
um we think
it's plausible
and we give some evidence in some
soluble examples in this case in an
example in one lower Dimension where we
can handle the equations better
that the quantum system that describes
the black hole
should correspond to a region of
space-time which is includes the photon
ring
so it's bigger hmm
so that that would be the holographic
plays so that would be the holographic
play all of that I mean we didn't prove
this we we
we uh you know we put it out there with
hadn't really been considered previously
we put it out there and
um it does seem more plausible than the
idea that it sits literally at the
Horizon and it is a big
outstanding problem of of how you have a
holographic reconstruction of black
holes like m87
do you think uh there could be
experimental further experimental data
that helps explore some of these ideas
that you have for Photon rings and
holographic plates through Imaging and
through like higher and higher
resolution images and also just more and
more data I wish so but I don't think so
and but what I think already has
happened and will continue happen
is that the you know there there are
many different ways that
uh theorists and
observers can interact
the gold standard is the theorist makes
a prediction The Observer
measures it and confirms it or the
Observer uh makes a
discovery and the theorist explains it
um but there's a lot less than that
which is really kind of the bread and
butter of those are dramatic moments
when that happens right those are once
in a lifetime moments when that happens
but the bread and butter is more when
and it already has already happened
they came to us and said what what is
the interesting theoretical things we
can understand
in this
swirl around the black hole and we give
an answer and then that
in turn jogged us to
think about the holographic principle in
the context of
m87 a little bit differently and so it's
a useful and in the same vein it's
useful to talk to the philosophers and
it's useful to talk to the
mathematicians and you know a lot of
you gotta we just gotta you know we
don't know where we're going we just
gotta like
do everything let me ask you another
sort of philosophical type question but
not really actually
um
it seems that thought experiments are
used so it's not just mathematics that
makes progress in theoretical physics
but thought experiments too they did for
Einstein as well they did for a lot of a
lot of great physicists throughout
history over the years how is your
ability to generate thought experiments
it's just your intuition about some of
these weird
things like quantum mechanics
or string theory
or quantum gravity
or yeah even general relativity how's
your intuition improved over the years
have you been able to make progress the
hard part in physics
is
most problems are
uh
either doable most problems the
theoretical calculation that are
theoretical physicists would do there
there's no end of problems
whose answer is uninteresting
can be solved but the answer is
uninteresting
there's also no end of problems that are
very interesting
some of which you've asked me but we
don't have a clue how to solve them
and when first presented with the
problem
almost every problem is one or the other
it's it's the jackpot when you find one
that isn't one or the other
and it seems like there's a gray area
between the two right that's where you
should be looking
well I wouldn't describe it as a gray
area I would describe it as a knife edge
this is a very small
area there isn't like a huge area with a
side hear life problems that are doable
and people want to know the answer and
that's in some deep sense that's where
timing is everything with physics with
with science with Discovery timing I
mean I think earlier in my career I I
aired more on the side of
problems that were
not solvable
the ambition of Youth
yeah what what what made you fall in
love with physics
at first if we can go back
to the early days you said black holes
were there in the beginning
but what made you do you remember what
really made you fall in love you know I
wanted to I wanted to reach nirvana and
I sort of realized that wasn't going to
happen and then after that I wanted to
know the meaning of life and I realized
I wasn't
probably wasn't going to figure that out
and then I wanted to like
understand you know
Justice and socialism and World things
and
couldn't figure those out either and the
simplest smaller and smaller problems
I mean most of this stuff talking about
adolescence you know but but uh it was
the biggest problem
that I thought that there was uh a
prospect of
but not a hundred percent you know and I
was definitely
ready to
spend my
my life in the wilderness knocking my
head against the wall but
I haven't
had to
I haven't solved them but
I've said enough interesting things that
you're you're you're you're you're
interviewing me so so I'm not in the
wilderness but yeah so do you remember
the the early days of if you feel
nostalgic when you think back to the
ideas the circumstances that let down
that led you down this
the path
towards black holes those theoretical
physics doors the tools of physics
stores this really fascinating world of
theoretical physics
well I wouldn't I wouldn't
add Nostalgia to it because
it's not like a
you know
a summer in Italy or something it's it's
like there there's
there's
results that are there that that people
are and that's what's that's what's so
gratifying
I mean of course one's name
disappears from these
these things
um unless you're Einstein or Newton or
something you're people are not gonna
remember my name in 50 years almost no
basically every nail will be forgotten
in hundreds of years yeah yeah are you
able to by the way
um love the idea the exploration of
ideas themselves without the names yeah
yeah that's what I'm saying so I have
not I hope someday but I have not
um you know there are some experiments
now to
verify some of my
predictions about you know properties of
gravity and so on but I I have not like
you know most of what I've done is in
the you know it could happen still it's
still a logical possibility that
everything having to do with string
theory and the uh I mean as I as we
mentioned I'm betting the farm that it's
not but but it is a lot indeed a logical
possibility that that people always say
can you believe
Lex Fred men interviewed Elon Musk and
Kanye West and
and he interviewed strominger who was on
this
this working on this theory that just
completely went into the yeah it
completely went into the toilet you know
I'm gonna make I'm gonna get uh with a
wife I don't have I'm gonna make a
public statement she'll be on stage I'll
say I'm really sorry I made this giant
mistake
of platforming this wild-eyed physicist
that believed for decades in the power
of theoretical physics yes no like you
said so that could happen it could
happen it could happen it's it's in the
and of course if that couldn't happen
yeah it wouldn't be real exploration
right absolutely and um
so but I I you know I do take a lot of
satisfaction that some of the things I
discovered are
at the minimum mathematical truths and
they're still so you don't have that
sort of nostalgic feeling of it being
something that was
gone and and uh and I'm still making
discoveries
now that I'm as excited about we'll see
if they
hold the test of time that
that stand the test of time that these
other ones did that but that I'm as
excited about as I
was about those when I when I when I
made them I am easily excitable as my
friends will tell you well one
interesting thing about you is and I
have been very excited about things
which turned out to be completely wrong
you know well that's the the excitement
is a precondition for uh for
breakthroughs
um but you're also somebody like just
like you said you don't have a cynical
view of the modern state of physics so
so there's a lot of people that glorify
like the early days of string theory and
that you know all these yeah
yeah yeah but you're saying like this
this to you uh might be one of if not
the most exciting times to be a
theoretical physicist like uh when uh
the alien civilizations 500 years from
now that visit Earth will look back
they'll think the 21st century some of
the biggest discoveries ever were made
in the 21st and they have a when they
have a measurement of string theory the
fund's over
then we have to go on to something new
you know no there's deep there's oh
there's going to be the fun is over oh
man
um but there is an end to the Nile right
I mean there that's there's is there
who told you
some Weber guy uh uh let me let me ask
you another trippy out there question uh
so uh again perhaps unanswerable from a
physics perspective but do you wonder
about
um alien civilizations do you wonder
about
other intelligent beings out there
making up their own math and physics
trying to figure out the world do you
think they're they're out there
it is hard to understand
why there were given that there's so
many planets and of course there's
Drake's formula and we don't exactly
know what the
but I mean I think fermi's Paradox that
you know
is a real Paradox and
I
I think they're
there probably are and I think it's very
exciting that uh
you know we might you know find some
it's it's a logical possibility that we
could learn about it I mean to me it's
super interesting to think about aliens
from a perspective of physics because so
any intelligent civilization is going to
be contending with the ideas but you're
trying to understand the world around it
so I think that the alien I think that
the universe is filled with alien
civilizations so they're all have their
physicists right they all have their
they're all trying to understand the
world around them and it's just
interesting to me to imagine all these
different perspectives all these
different Einsteins yeah like trying to
make sense of like though they might be
more different than we think they might
be different in a way that we haven't
even thought of like smarter or
different
just just different something that we
don't even we're not even able to
describe now we just haven't thought
about it you know man
yeah this is a really frustrating thing
when we think from uh me as an AI person
you start to think about what is
intelligence which is consciousness you
start to sometimes again uh night
evening thoughts is um
how little we understand how narrow our
thinking is about these Concepts yeah
yeah that that it could be intelligence
could be something could be intelligent
and be very different intelligent in a
very different way they won't be able to
detect because we're not keeping an open
mind open enough mind
and that's kind of sad because to me
there's also just a strong possibility
that aliens or something like alien
intelligence or some
fascinating beautiful physical phenomena
are all around us
and we're too dumb to see it
for now
or to close-minded to see it
there's something we're just deeply
missing whether it's uh like fundamental
limitations of our cognitive abilities
or just because our tools are too
primitive right now
or like the way we it's like you said
like uh
the idea seemed trivial once you figure
it all out looking back yeah but
that kind of makes me sad because there
could be so much Beauty in the world
we're not seeing
because we're too dumb there surely is
and that's I guess the process of
Science and physics is to keep exploring
to keep exploring
to find the thing that will uh in a
century seem obvious
well it's something we know for sure I
mean the brain we don't
really understand and that's got to base
some
fabulously beautiful story that uh I'm
hoping some of that story will be
written through the process of trying to
build a brain so the process of
engineering intelligence not just the
neuroscience perspective of just looking
at the brain but trying to create it
uh
but yeah that story hasn't been written
almost at all which is the early days of
figuring that one out but see like you
said that math is discovered so
um aliens should at least have the same
math as us
right I think so maybe different symbols
oh well they might have discovered
different
they might have discovered it
differently
and they might have had a different idea
of what a proof is
sure yeah we're very uh we're very like
black and white with the proof thing
yeah maybe they're looser
right well so you can you can know
something is true
to first of all you never know something
is true with 100 uncertainty I mean
you might have had a blackout it's just
to be it's never a hundred percent right
you you might have had a momentary lapse
of Consciousness it's a key step in the
proof and nobody read it and whatever
okay so you never know for sure
but you can
be have a preponderance of evidence
which makes it
and preponderance of evidence
is not accepted very much
in mathematics and
and that was sort of
how you know the famous ramanujan work
he worked he had
formulas which he guessed at and then he
gathered a preponderance of evidence
that that you were sure they were true
and so there might be or something
completely different you know they might
function in a different in a very
different way
let me ask you um kind of a heavy
question for a physicist but one on
nuclear weapons
just in general what do you think about
nuclear weapons where like philosophical
level
where brilliant physicists and Brilliant
engineering leads to thing that can
destroy human civilization
sort of like some of the ideas
that you're working on
have power when it when engineered into
machines into systems is there some
aspects I don't know what the brilliant
had to do with it because of course
you know Oppenheimer and all that okay
they did it really fast but if you
didn't have Oppenheimer yeah you know I
mean would all have happened anyway
it it's the it had a reality of its own
the possibility of making a nuclear
didn't it didn't depend on the fact that
the physicists who built it were
brilliant maybe that
bed it up by a year two years or but by
now we'd have nuclear weapons it's it's
something that so the ideas have
momentum and that they're um yeah
Unstoppable right the possibility of
making nuclear weapons was discovered
right it was there before
we didn't we didn't it's not like
somebody made it right
um
without Picasso
you know there would never have been a
Guernica but without Oppenheimer that
would surely have still been
an atom bomb
but timing matters right timing is very
important there's a guy of course of
course of course but the timing matter
the timing mattered there
um
but I
I yeah
uh okay I mean you could try to make a
case for
stopping uh no no no it's the case of
carrying the burden of the
responsibility of the power of ideas
when manifested through into systems so
there's not it's not a game it's not
just a game a fun mathematics the same
with artificial intelligence you have
this you know a lot of people in AI yeah
you know in a lot of people in the AI
Community it's a fascinating fun puzzle
how to make systems more and more
intelligent how to you have a bunch of
benchmarks you try to make them perform
better and better and better and all of
a sudden you have a system that's able
to all smart people
it's now able to be used in geopolitics
it's able to create a super intelligent
Bots that are able to at scale control
the belief of a population of people and
now you can have world wars you can have
a lot of really risky instabilities they
really are incredible and so to think
like there's some responsibility this is
not sort of
um
it's a beauty and a power and a terror
to these ideas you know
yeah
at that moment it was certainly a
question for Oppenheimer and everybody
who participated in that what it what is
the responsible way to
serve Society
when you're
sort of accidentally in this position of
being at the Forefront of
a development that has a huge impact on
society I I don't see my work
the likelihood of having a huge impact
on the development of society itself but
if I were you
oh I love this working on AI yeah I
think that there is a possibility there
and that it is as a responsible
scientist that it's really not a good
thing to say I'm just the scientist here
and I'm figuring out what's possible
because
you're in a role where you
you're you know you have more of a
a Podium to influence things than other
people and
it's your responsibility is it citizen
of the planet or or let me phrase it a
little less shouldy it's you know you
have an opportunity yeah as a citizen of
the planet to
make the world a better place which
which it would be sad too
to bypass yeah it's a nice world without
going it'd be nice to keep it going for
a little bit longer Andrew
um I'm really honored that you sit down
with me this is uh thank you for your
work thank you it was it was a really
great conversation I really enjoyed it
you really uh you really covered a lot I
can't believe you're able to
discuss at this level on so many
different uh topics so it's a pleasure
it was it was super fun thank you
thanks for listening to this
conversation with Andrew stromiger to
support this podcast please check out
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let me leave you some words from Warner
Heisenberg
not only is the universe Stranger than
we think
it is stranger than we can think
you for listening and hope to see you
next time