Kind: captions
Language: en
the following is a conversation with
barry barish a theoretical physicist at
caltech and the winner of the nobel
prize in physics for his contributions
to the ligo detector and the observation
of gravitational waves
ligo or the laser interferometer
gravitational wave observatory is
probably the most precise measurement
device ever built
by humans
it consists of two detectors with four
kilometer long vacuum chambers situated
three thousand kilometers apart
operating in unison to measure a motion
that is ten thousand times smaller than
the width of a proton
it is the smallest measurement ever
attempted by science a measurement of
gravitational waves caused by the most
violent and cataclysmic events in the
universe
occurring over tens of millions of light
years away
to support this podcast please check out
our sponsors in the description
this is the lex friedman podcast and
here is my conversation with barry
barish
you've mentioned that you were always
curious about the physical world and
that an early question you remember
stood out where you asked your dad
why does ice float on water and he
couldn't answer and this was very
surprising to you
so you went on to learn why
maybe you can speak to what are some
early questions in math and physics that
really sparked your curiosity yeah
that memory is
kind of something i used to illustrate
something i think that's common in
science that people that do science
somehow have maintained
maintain something that kids always have
a small kid
eight years old or so
asks you so many questions usually
typically that you
consider them pests you tell them to
stop asking so many questions
and
somehow our system manages to kill that
in most people
so in school we make people do study and
do their things but not to pester them
by asking too many questions
and
i think
not just myself but i think it's typical
of scientists like myself that uh
have somehow escaped that maybe we're
still children or maybe we
somehow didn't get it beaten out of us
but
i think it's i teach in a college level
and it's to me
one of the biggest deficits is the lack
of curiosity if you want that we've
beaten out of them because i think it's
an innate human quality is there some
advice or insights you can give to how
to keep that flame of character i think
it's a problem of both parents and
and
the parents should be should realize
that's a great quality we have
that you're curious and that's good
instead we have we have expressions like
curiosity killed the cat
and
and uh
and more but i mean that basically it's
not not thought to be a good thing you
get curiosity killed the cat means if
you're too curious you get in trouble
and i don't like catholics anyway so
maybe it's a good thing yeah yeah
that to me needs to be solved really in
education and in homes it's a
realization that there's certain human
qualities that we should try to build on
and not destroy one of them is curiosity
anyway back to me in curiosity i was
passed and asked a lot of questions my
father generally could answer them
and at that age
and the first one i remember that he
couldn't answer
was
not a very original question but
basically that
ice is made out of water and so why does
it float on water
and
he couldn't answer it
and it may not have been the first
question it's the first one that i
remember and and that was the first time
that i realized that
to learn and answer your own curiosity
or questions there's various mechanisms
in this case it was going to the library
and
or asking people who know more and so
forth but
eventually you do it by what we call
research
but but it's um
driven by
if you're
hopefully you ask good questions if you
ask good questions and you have the
mechanism to solve them then you do what
i do in life basically not necessarily
physics but
and it's a great quality in humans and
we should nurture it
do you remember any other kind of in
high school maybe early college
more basic physics ideas
that sparked your curiosity or
mathematics or science engineering i
wasn't really into science
until i got to college to be honest with
you
but
just staying with water for a minute i
remember
that i
was curious
uh
why uh what happens to water you know it
rains and there's water in a wet
pavement and then the pavement dries out
what happened to this
water that came down
and i you know i didn't know that much
and then eventually i learned in
chemistry or something water is made out
of hydrogen and oxygen those are both
gases so how the heck does it make this
substance this liquid
[Laughter]
yeah so but so that has to do with
states of matter
you've uh i know
perhaps ligo and
the the thing for which you've gotten
the nobel prize and the things much of
your life work
perhaps was a happy accident in some
sense in the early days but is is there
a moment where you looked up to the
stars and also the same way you wondered
about water wandered about some of the
things that are out there in the
universe
oh yeah i think everybody's
looks and
is in awe and is curious about
what what it is out there and you know
and as i learned
more i learned
of course that we don't know very much
about what's there and the more we learn
the more we know we don't know i mean we
don't know what the majority of anything
is out there it's all
what we call dark matter a dark energy
and that's one of the big questions 20
year when i was a student those weren't
questions so we even know less in a
sense the more we
uh the more we look so
of course i think that's
one of the areas that
almost it's universal people see the sky
they see the stars and they're beautiful
and
and see it looks different on different
nights and it's a curiosity that we all
have
what are some questions about the
universe
that in the same way that you felt about
the ice
that today
you mentioned to me offline you're
teaching um a course on the frontiers of
science frontiers of physics yeah what
are some questions
outside the ones we'll probably talk
about that kind of
yeah fill you with uh
get your flame of curiosity up and uh
firing up
yeah you know fill you with all
well first i'm a physicist not an
astronomer so i'm interested in physical
the physical phenomenon really so
the question of of uh
dark matter and dark energy which we
probably won't talk about are rece or
recent their last 20 30 years or
certainly dark energy
dark energy is a complete puzzle
it goes against what i'll
will what you will ask me about which is
general relativity and einstein's
general relativity it basically takes
something that he thought was
what he what he called a constant which
isn't and
and uh
in the if that's even the right theory
and it represents most of
the universe
and then we have something called dark
matter and there's good reason to
believe it might be an exotic form of
particles um and that is something i've
always
worked on on particle accelerators and
so forth and it's a big puzzle what it
is it's a bit of a cottage industry and
that there's
lots and lots of searches
um but it may be a little bit like you
know looking for a treasure under rocks
or something you know it's hard to
we don't have really good guidance
except that
we have very very good
information that
it's pervasive and it's there
and that it's probably particles small
that the evidence is all of those things
but then the most
uh logical solution doesn't seem to work
something called supersymmetry
and
do you think the answer could be
something very complicated
you know i like to hope that think that
most things
that appear complicated are actually
simple if you really understand them
i think we just don't know at the
present time and it isn't something that
affects us it does affect it affects how
the stars go around each other and so
forth because we detect that there's
missing gravity but
uh but it doesn't affect
everyday life at all i tend to
think and
expect maybe and that the answers will
be simple we just haven't found it yet
do you think those answers might change
the way we see
other sources of gravity black holes
the way we see
the parts
of the universe that we do study it's
conceivable
the black holes that we've found in our
experiment and now we're trying now to
understand the origin of those
it's
conceivable but not
doesn't seem the most likely that they
were pre-primordial that is they were
made at the beginning and they in that
sense they could represent at least part
of the dark matter
so there can be connections dark
black holes or
how many there are how much of the mass
they encompass is still pretty primitive
we don't know so before i talk to you
more about black holes let me take a
step back to yeah i was actually went to
high school in chicago and would go to
uh take classes at fermi lab
uh watch the buffalo and so on yeah
so let me ask about you mentioned that
enrico for me was somebody who was
inspiring to you
in a certain kind of way um
why is that can you speak to that sure
he was amazing actually uh
he's the last
this is not the re i'll come to the
reason in a minute but the
he had a big influence on me at a young
age
he uh but he was the only the last
physicist
of note
that was both an experimental physicist
and a theorist at the same time
and he did two amazing things within
months
in 1933.
he
it was we didn't really know what the
nucleus was what uh
radioactive decay was what beta decay
was when electrons come out of
a nucleus
and in
nearly near the end of 1933
um he
the neutron had just been discovered and
that meant that we knew a little bit
more about what the nucleus is that it's
made out of neutrons and protons the
neutron wasn't discovered till 1932
and then once we discovered that there
was a neutron and proton and they made
the nucleus and then their electrons
would go around the basic ingredients
were there
and he uh wrote down not only just the
theory a theory but a theory that lasted
decades
and has only been
improved on
of beta decay that is the radio
radiation he did this
came out of nowhere and it was a
fantastic theory he submitted it to
nature
magazine which was the primary
play best place to publish even then
and it got rejected as being too
speculative
and so he went
back to his
drawing board in rome where he was
added some to it made it even longer
because it's really a classic article
and then published it in
the local italian
journal for physics and the german one
at the same time in 19 january of 1932
giulio and curie for the first time
steve saw artificial radioactivity
this was an important discovery because
radioactivity had been discovered much
earlier and you know we'd they had
x-rays and you shouldn't be
using them but they there was
radioactivity people knew it was useful
for medicine
but radioactive materials are hard to
find and so it wasn't prevalent but if
you could make them
then they had great use and julio and
curie
were able to bombard
aluminum or something with alpha
particles and
find that they excited something that
decayed and gave
decayed and gate had some half-life and
so forth meaning it was artificial
version
or let's call it a not not a natural
version an induced version of
radioactive uh
materials
and uh
fermi
somehow
had the insight
and i still can't see where he got it
that the right way to follow that up was
not using
charged particles like alphas and so
forth but use use these newly discovered
neutrons as the bombarding particle
seemed impossible they barely had been
seen
it was hard to get very many of them
but it had the advantage that they don't
um they're not charged so they go right
into the
to the nucleus
and that turned out to be the
experimental work that he did that won
him the nobel prize
and it was the first step in fission
discovery of fission
and that's he did this two completely
different things an experiment that was
a great idea
and a
tremendous implementation because how do
you get enough neutrons
and then he learned
quickly that not only do you want
neutrons but you want really slow ones
he learned that experimentally and he
learned how to make slow ones and then
they were able to make go through the
periodic table and make
lots of
particles he missed on fission at the
moment but he had the basic information
and and then fission followed soon after
that forgive me for not knowing but is
the birth of the idea of bombarding with
new uh
neutrons
is that uh
is that an experimental idea was it born
out of an experiment you just observe
something or is this an einstein style
idea where you
took a combination because he realized
that neutrons had a characteristic that
would allow them to go all the way into
the nucleus when we didn't really
understand what the
you know what how what the structure was
of all this so that took
uh
an understanding or recognition of the
physics itself of how a neutron
interacts compared to say an alpha
particle that giulio and curie had used
and then he had to invent
a way to have enough neutrons and uh you
know what he had a team of
associates and he pulled it off
quite quickly so you know it's pretty
astounding and probably maybe you can
speak to it
his ability to put together
the engineering aspects of great
experiments
and doing the theory they probably fed
each other i wonder can you speak to why
we don't see more of that is that just
really difficult to do
it's difficult to do yeah i think in
in both theory and experiment in physics
anyway
was um
it was conceivable if you had an the
right person to do it and no one's been
able to do it since so i had the dream
that that
was what i was going to be like fermi
but so you love both sides of it the
theory yeah yeah i never liked the idea
that you did experiments without really
understanding the theory or the theory
should be related very closely to
experiments
and so i've always done
experimental work that was closely
related to the theoretical ideas
i think i told you i'm russian so i'm
going to ask some romantic questions but
is it tragic to you that
he's seen as the architect of the
nuclear age that some of his creations
led to potentially
some of his work
has has led to
potentially still the destruction of the
human species some of the most
destructive
weapons yeah
uh
but i think even more general than him i
i i gave you all the virtues of
curiosity a few minutes ago there's an
interesting book called the ratchet of
curiosity you know a ratchet is
something that goes in one direction
and that that it's written by a guy
who's probably a sociologist or
philosopher or something
and he he picks on this particular
problem but other ones and that is the
the danger of knowledge basically you
know you're curious
you learn something so it's a little bit
like curiosity killed the cat you have
to be worried about whether you can
handle
new information that you get so in this
case the new information had to do with
really understanding nuclear physics
and that information maybe we didn't
have the sophistication to know how to
keep it under control
yeah and fermi himself was
a very a political person so he wasn't
very driven by or or at least
he appears in all of his writing the
writing of his wife the interactions
that others had with him as either he
avoided it all or he was pretty
apolitical i mean he just saw the world
through kind of the lens of a scientist
but you asked if it's tragic uh
the bomb was tragic certainly on japan
and he had a role in that so i wouldn't
want it as my legacy for example
i mean that but broader to the human
species that
it's the ratchet of curiosity that we
uh
we do stuff just to see what happens
that that curiosity that uh in sort of
my area of artificial intelligence
that's been a concern
they're on a small scale on a silly
scale perhaps currently there's
constantly
unintended consequences you create a
system
and you put out there and you have
intuitions about how it will work you
have hopes how it will work but you put
it out there just to see what happens
yeah and uh in most cases because
artificial intelligence is currently not
super powerful it doesn't
create uh large-scale negative effects
but that same curiosity as it progresses
might lead to something that
destroys the human species and the same
may be true for bioengineering there's
people
that
you know engineer viruses to protect us
from viruses
to see you know how do uh how close is
this to mutating so it can jump to
humans or going you know or engineering
uh defenses against those
and it seems exciting and the
application the positive applications
are really exciting at this time but
we don't think about
how that runs away in decades to come
yeah and i think it's the same idea as
this little book the ratchet of
science the the
uh ratchet of curiosity i mean
whether you pursue take curiosity and
let
artificial intelligence or machine
learning run away with
having its
solutions to whatever you want or we do
it
it's i think a similar consequence
i think uh from what i've read about uh
enrico for me he
he became a little bit cynical about the
human species towards the end of his
life
both having observed what he observed
we didn't write much
i mean he died young he died soon after
the world war uh
there was already you know
the
work by teller to develop the hydrogen
bomb and i think he was a little cynical
of that you know pushing it even further
and
uh rising tensions between the soviet
union and the u.s and looked like an
endless thing so but he didn't say very
much but a little bit as you said yeah
there's a few clips to sort of uh maybe
picked on a bad mood but in in the sense
that uh almost like a sadness a
melancholy sadness to
um
a hope that waned a little bit about
that uh yeah perhaps we can do
like
the science this curious species can
find the way out
well especially i think people who
worked like he did at los alamos and
spent years of their life
somehow had to convince themselves that
dropping these bombs would bring
lasting peace and it didn't and that it
didn't yeah
as a small interesting aside it'd be
interesting to hear if you have opinions
on this his name is also attached to the
fermi paradox which asks if there's uh
you know with
it's a very interesting question which
is
if it does seem if you sort of reason
basically that there should be a lot of
alien civilizations out there if the
human species
if earth is not that unique
by
basic
no matter the values you pick
it's likely that there's a lot of alien
civilizations out there and if that's
the case
why have they
not at least obviously visited us or
sent us loud signals that everybody can
hear
fermi's quoted as saying sitting down at
lunch i think it was with
teller
and uh herb york who was kind of the one
of the fathers of the atomic bomb
and he sat down and he says something
like where are they
yeah
which meant where are these
other and
um
and then he did some
numerology where he
calculated you know how many what they
knew about how many
uh
galaxies there are and how many stars
and how many planets in are like the
earth and blah blah blah that's been
done much better by somebody named drake
and so people usually refer to the i
don't know whether it's called the drake
formula or something but it has the same
conclusion
the conclusion is it would be a miracle
if there weren't other
you know uh there's the statistics are
so high that how can we be singular and
separate
that so probably there is
but there's
almost certainly life somewhere
maybe there was even life on mars a
while back but
uh
intelligent life
probably why were we so so you know the
statistics say that communicating with
us
i think that it's harder than people
think
we might
not know the right way to
expect the communication
but all the communication that we know
about travels at the speed of light
and we do we don't we don't think
anything can go faster in the speed of
light that
limits the problem quite quite a bit and
it uh
makes it difficult to have any back and
forth communication you can send signals
like we try to or
look for but to have any communication
it's pretty hard when you it has to be
close enough that the speed of light
would mean we could communicate with
each other and i think
and we didn't even understand that i
mean it's an advanced civilization but
we didn't even understand that
a little more than 100 years ago
so uh
are we
just not advanced enough maybe
uh to know something about that's the
speed of light maybe there's some other
way to communicate that isn't based on
electromagnetism i don't i don't know
gravity seems to be also this have the
same speed that was a principle that
einstein had and something we've
measured actually
so is is it possible i mean so we'll
talk about gravitational waves and
it in some sense there's a
there's a brainstorming going on which
is like
how do we detect the signal like what
would a signal look like and how would
we detect and that's true for
gravitational waves that's true for
basically any physics phenomena
you have to predict that that signal
should exist you have to have some kind
of theory and model why that signal
should exist i mean is it possible that
aliens are communicating with us via
gravity
like why not well it it
yeah it's true why not uh
for us it's very hard to detect these
gravitational effects they have to come
from something
pretty that has a lot of gravity like
black holes but we're pretty primitive
at this stage
there's uh
very reputable physicists that look for
a fifth force
one that we haven't found yet maybe it's
the key so you know
it's what would that look like what
would a fifth force of physics look like
exactly well usually they think it's
probably a long range for longer range
force than we have now
um
but uh
they're reputable for colleagues of mine
that spend their life looking for a
fifth force so longer range than gravity
yeah
super it doesn't fall off like one over
r squared but maybe
separately
gravity
uh newton taught us goes like inversely
one over the square of the distance
apart you are so it falls pretty fast
that's okay so now we have a theory of
what consciousness is it's just the
fifth force of
physics yeah there we go that's a good
hypothesis
uh
speaking of gravity uh of gravity uh
what are gravitational waves let's maybe
start from the basics
we learned gravity from newton
right you you and you were young you
were told that if you jumped up the
earth pulled you down
and when the apple falls out of the tree
the earth pulls it down
and maybe you even asked your teacher
why but
most of us
accepted that that was newton's
picture the apple falling out of the
tree but newton's theory never told you
why the apple was attracted to the earth
that was a missing in newton's theory
newton's theory also
newton recognized at least one of the
two problems i'll tell you one of them
is there's more than those but one is
why does the earth what's the mechanism
by which
the earth pulls the apple or holds the
moon when it goes around whatever it is
uh that's not explained by newton even
though he has the most successful theory
of physics ever went 200 and some years
with nobody ever seeing
a violation but he accurately describes
the movement of an object falling down
to earth but he's not answering why that
what's yeah yeah because it's a distance
he gives a formula right which which
it's the product of the earth's mass the
apple's mass
inversely proportional to the square the
distance between and then the strength
he called capital g the strength he
couldn't determine but it was determined
100 years later
but no one ever saw a violation of this
until a possible violation which
einstein fixed which was very small that
has to do with mercury going around the
sun
the orbit being slightly
wrong if you calculated by
newton's theory
but so
um like most theories then in in physics
you can have a wonderful one like
newton's theory it isn't wrong
but you have to have a
an improvement on it to answer things
that it can't answer and in this case
einstein's theory is the next step we
don't know if it's
anything like a final theory or even the
only way to formulate it
either
but he formulated this theory
which
which he
released in 1915
he took 10 years to develop but even
though in 1905 he solved three or four
of the most important problems in
physics in a matter of months and then
he spent 10 years on this problem before
he
uh let it out and it's called general
relativity it's a new theory of gravity
1915 in 1916
einstein
wrote a little paper
where he
did not do some fancy derivation instead
he did
what i would call it used his intuition
which he was very good at too
and that is he noticed that if he formed
if he wrote the formulas for general
relativity in a particular way
they looked a lot like the formulas for
electricity and magnetism
being einstein he then took the leap
that electricity and magnetism we
discovered only 20 years before that in
the 1880s
have waves of course that's
light and electromagnetic rays radio
waves everything else so he said if the
formulas look similar
then gravity probably has ways too
that's such a big leap by the way i mean
maybe you can correct me but that just
seems
so that seems like a heck of a look yeah
and so that and it was considered to be
a heck of a leap so first that paper was
except for this
intuition was
uh
poorly written had had a serious mistake
it had the a factor of two wrong and the
strength of gravity which meant if we
use those formulas we would
and
two years later
he wrote a second paper
and in that paper it turns out to be
important for us because in that paper
he not only
fixed his factor of two mistake which he
never admitted he just wrote it fixed it
like he always did and
and then he
told us
how you make gravitational waves what
what makes gravitational waves
and
you might recall in electromagnetism we
make electromagnetic waves in a simple
way you take a plus charge and minus
charge you oscillate like this and that
makes electromagnetic waves
and a physicist named hertz
made a receiver that could detect the
waves and put in the next room
he saw them and moved forward and
backward and saw that it was wave-like
so
einstein said it won't be a dipole like
that it'll be a four-pole thing and
that's what
it's called a quadrupole moment that
gives the gravitational wave so he saw
that again by insight not by derivation
that's at the table for what you needed
to do to do it at the same time in the
same year schwartz child not einstein
said there were things like called black
holes so it's interesting that that came
the same so what year was that
2015.
it was in parallel
with i did
i should probably know this but did i
say not have any intuition that there
should be such things as black holes
that came from schwarzschild oh
interesting
yeah
so schwartz child who was a
a german theoretical physicist he got
killed in the war i think in the first
world war a year two years later
or so
he's the one that proposed black holes
that there were black holes it feels
like a natural conclusion of uh general
relativity you know
or is that uh
[Music]
well it may seem like it but i don't
know about a natural conclusion it is a
it's a result
of curved space time though right and
it's but it's such a weird result that
you might have to uh yeah it's a special
yeah it's a special case yeah
so um
i i don't know anyway
einstein then the interesting part of
the story is that einstein then left the
problem most physicists because it
really wasn't uh derived he just made
this
didn't pick up on it or general
relativity much because quantum
mechanics became the thing in physics
and
einstein
uh
only picked up this problem again after
he immigrated to the u.s so he came to
the u.s in 1932
and i think in 1934-5
he was working with another physicist
called rosen who he did several
important works with and they revisited
the question
and they
had a problem that most of us as
students always had that study general
relativity general relativity is really
hard because it's four-dimensional
instead of three-dimensional and if you
don't set it up right you get infinities
which don't belong there the we call
them coordinates singularities
as a name
but it but if you get these infinities
you don't get the answers you want and
he was trying to derive now general
relativity out from general relativity
gravitational waves and in doing it he
kept getting these infinities
and so he wrote a paper with rosen that
he submitted to
our most important journal physical
review letters
and
that when it was submitted to physical
review letters it was entitled do
gravitational waves exist
a very funny title to write 20 years
after he proposed they exist
but it's because he had found these
singularities these infinities
and so
the
editor at that time and the part of it
that i don't know
is peer review we live and die by peer
review as scientists send our stuff out
and it's we don't know when peer review
actually started
or what what peer review einstein ever
experienced before this time but the
editor of physical review sent this out
for review
he had a choice he could take any
article and just accept it he could
reject it or he could send it for review
right i believe the editors used to have
much more power yeah yeah and he was a
young man his name was tate and he ended
up being an editor for years but
so he sent this for review
to
a theoretical physicist named robertson
who was also in this field of general
relativity who happened to be on
sabbatical at that moment at caltech
otherwise his institution was princeton
where
einstein was
and he
saw that the way they set up the problem
the infinities were like i might get as
a student because if you don't set it up
right in general relativity you get
these
infinities
and so he reviewed the article and told
he gave an illustration that they set it
up in what are called cylindrical
coordinates these infinities went away
he's the
editor of
uh physical review was obviously
intimidated by einstein he wrote this
really not not a letter back like i
would get saying you know you're screwed
up in your paper instead
it was kind of uh
what do you think of the comments of our
[Laughter]
referee einstein wrote back and it's a
well documented letter wrote back a
letter to physical review saying
i didn't send you the paper
to send it to one of your so-called
experts i sent it to you to publish
i now i withdraw the paper
and he never published again in the in
that journal that was 1936 instead
he
rewrote it
with the fixes that were made changed
the title
and published it in what was called the
franklin review which is the
uh franklin institute in philadelphia uh
which is benjamin franklin institute
which doesn't have a journal now but
did at that time so the article is
published it's the last time he ever
wrote about it
it remained controversial
so it wasn't until
close to 1960 1958 where there was a
conference in which brought that brought
together
the
experts in general relativity to try to
sort out whether there was uh
um
whether
it was true that there were
gravitational waves or not
and there was a very nice
derivation by a british
theorist
from
the heart of the theory that gets
gravitational waves
uh and that was number one the second
thing that happened at that meeting is
richard feynman was there
and feynman
said well if there's a typical feynman
if there's gravitational waves they need
to be able to do something otherwise
they don't exist so they have to be able
to transfer energy so he made a
idea of a gadonkan experiment that is
just a bar
with a couple rings on it
and then if a gravitational wave goes
through it distorts the bar
that creates friction on these little
rings
and that's heat and that's energy so
that that meant is that a good idea that
sounds like a good idea yeah it means
that he showed that
with the distortion of space-time you
could transfer energy just by this
little idea and it was shown
theoretically so at that point
it was
believed theoretically then by
people that gravitational waves should
exist
no and we should be able to detect them
we should be able to detect them except
except that they're very very small
just so what kind of uh there's a bunch
of questions there but what kind of
events
would generate
gravitational waves you have to have
this what i call quadrupole moment that
comes about if i have uh
for for example two objects that go
around each other like this like the
earth or the earth around the sun or the
moon around the earth or in our case it
turns out to be two black holes going
around each other like this so how's
that different than basic oscillation
back and forth this is just more common
in nature oscillation is a dipole moment
so it has to be in three-dimensional
space yeah kind of oscillations so you
have to have something that's
three-dimensional that'll give what's
what i call the quadrupole moment that's
just built into this and luckily in
nature you have stuff
and luckily things exist
and it is luckily because the effect is
so small that you could say look i can
take a barbell
and
and spin it right and detect the
gravitational waves but unfortunately no
matter how much i spin it how fast i
spin it it's so i know how to make
gravitational waves but they're so weak
i can't detect them so we have to take
something that's stronger than i can
make otherwise we would do what hertz
did for electromagnetic waves go in our
lab
take a barbell put it on something spin
it ask a dumb question so a uh a single
object that's weirdly shaped does that
generate gravitational waves so if it's
if it's rotating
sure
it it was just much weaker
it's weaker well we didn't know what the
strongest signal would be that we would
see
uh we targeted seeing something called
neutron stars actually because black
holes we don't know very much about it
turned out we were a little bit lucky
there was a stronger source which was
the black holes well another ridiculous
question so
you say waves what is what does a wave
mean like
the most ridiculous version of that
question is what does it feel like
to uh ride a wave as you get closer to
the source
or experience it well if you experience
a wave imagine that this is what happens
to you
i don't know what you mean about getting
close it comes to you so it's like it's
like uh this light wave or something
that comes through you so when the light
hits you it
makes your eyes detected
i flashed it what does this do is
it's like going to the amusement park
and they have these mirrors you look in
this mirror and you look short and fat
and the one next to you makes you tall
and thin
okay
imagine that you went back and forth
between those two mirrors once a second
that would be a gravitational wave with
a period of once a second
uh if you did it 60 times a second go
back and forth and
and then that's all that happens it
makes you taller and shorter and fatter
back and forth as it goes through you
at the frequency of the gravitational
wave so
the frequencies that we detect are
higher than one a second but that's the
idea so but uh and the amount is small
amount is small but when if you're
closer to the
to the source of the wave is it the same
amount
yeah it's it doesn't dissipate it
doesn't dissipate
okay so it's not that fun of an
amusement ride well it it does dissipate
but it doesn't it doesn't it's it's just
it's proportional to the distance right
it's not uh it's not a big power right
gotcha so but so
it would be a fun ride if you get a
little bit closer or a lot closer
i mean like i i wonder what the
this is a ridiculous question but i have
you here
like the getting fatter and taller
i mean that experience
for some reason that's mind-blowing to
me
it brings
the distortion of space-time to you
i mean space-time is being morphed
right like this is a way right
that how that's so weird and we're in
space so yeah we're in space and it's
moving
i don't know what to do with it i mean
does it okay um
how much do you think about the
philosophical implications of
general relativity like that we're in
space time
and it can be bent by gravity
like
is that just what it is are we are we
supposed to be okay with this
because like newton
even newton is a little weird right but
that at least like makes sense that's
our physical world
you know when an apple falls it makes
sense
but like the fact that entirety of
the space time we're in can bend
well that's uh
that's i that's really mind-blowing
let me make another analogy this is a
therapy session for me at this point
right another analogy thank you so so
imagine you have a trampoline yes
okay
what happens if you put a marble on a
trampoline it doesn't do anything right
no just saves a little bit but not much
yeah i mean just if i drop it it's not
going to go anywhere
now imagine i put a bowling ball at the
center of the trampoline
now
i come up to the trampoline and put a
marble on what happens
they'll roll towards the bowling ball
all right so what's happened is the
presence of this
massive object distorted the space
that the trampoline did
this is the same thing that happens to
the presence of the earth
the earth and the apple the presence of
the earth affects the space around it
just like the
uh bowling ball on the trampoline yeah
this doesn't make me feel better i'm
referring from the perspective of an
aunt
walking around on that trampoline
then
some guy just dropped the ball and not
only dropped the ball right it's not
just dropping a bowling ball it's making
the the ball go up and down
or doing some kind of oscillation thing
where it's like waves
and that's so fundamentally different
from the experience on being on flat
land and walking around and just finding
delicious sweet things as ant does and
just it just feels like to me from a
human experience perspective
completely it's humbling it's truly
humbling
it's something but we see that kind of
phenomenon all the time
let me give you another example imagine
that you walk up to a
a still pond
yes okay
now i throw
it you like to throw you throw a rock in
it what happens
the rock goes in sinks to the bottom
fine and these little ripples go out
yeah and they travel
out that's exactly what happens i mean
there's a disturbance
which is the safe
the bowling ball or our black holes and
then the ripples that go out in the
water they're not they don't have any
they don't have the rock any part pieces
of the rock i see the thing is i guess
what's not disturbing about that
is it's a i mean it's a i guess a flat
two-dimensional surface that's being
disturbed
like for a three-dimensional surface a
three-dimensional space to be disturbed
feels weird it's even worse it's
four-dimensional because it's space and
time yeah
so that's why you need einstein is to
make it uh
four-dimensional no
to make it four-dimensional yeah yeah
it's gonna take the same phenomenon and
and
look at it in all of space and time
anyway luckily
for you and i and all of us
the amount of distortion is incredibly
small
so it turns out
that if you think of space
itself now this is going to blow your
mind too if you think of space as being
like a material like this table
it's very stiff you know we have
materials that are very pliable
materials that are very stiff
so
space itself is very stiff
so when gravitational waves come through
it luckily for us it doesn't distort it
so much that it affects our ordinary
life very much
no i mean that's great
that's great i thought there was
something bad coming no this is great
that's great news so i mean that i mean
perhaps we evolved as the life on earth
do we
so to be such that for us this
particular set of uh effects of
gravitational waves
uh is not that significant maybe maybe
that's why you probably used
this effect today
or yesterday
so it's it's pervasive well you mean
gravity or the way the external
because i only curvature of space
curvature of space how i only care
personally as a human right the gravity
of earth but you use it every day almost
oh it's curving uh-huh no no no it's in
this thing
every time it tells you where you are
yeah
it how does it tell you where you are
it tells you where you are because we
have 24 satellites or some number that
are going around in space and it
asks how long it takes the
being
to go to the satellite and come back the
signal to different ones and then it
triangulates and tells you where you are
and then if you go down the road it
tells you where you are do you know that
if you did that with the satellites and
you didn't use einstein's equations oh
no
you want it you won't get the right
answer that's right and
in fact if you take a road let's say 10
meters wide i've done these numbers and
you ask how long you'd stay on the road
if you didn't make the correction
for
general relativity this thing you're poo
pooing because you're using every day
uh you'd go off the road and you'd go
the middle road well actually that might
be so you use it so so well
well i think i'm using an android so
maybe and the gps doesn't work that well
so maybe i'm using newton's physics uh
so i need to upgrade to general
relativity um so
gravitational waves and einstein
had uh wait fireman really does have a
part in the story was that one of the
first kind of experimental pro
proposed detect gravitation well he did
what we call a gadonkan experiment
that's a thought experience okay not a
real experiment but then after that
then people believe gravitational waves
must exist you can kind of calculate how
big they are there's tiny
and so
people started searching the first idea
that was used was feynman's idea
and the
very end of it
and it was to take a great big
huge bar of aluminum
and then put around and it's a it's made
like a cylinder
and then put around it some very very
sensitive detectors so that if a
gravitational wave happened to go
through it it would go
and you detect this extra strain that
was there and that was this method that
was used until we came along it wasn't a
very good method to use
and what was the
so we're talking about a pretty weak
signal here yeah that's why that method
didn't work so what can you tell the
story of figuring out what kind of
method would be able to detect
this very weak signal of gravitational
waves
so
remembering the
remembering what happens if you when you
go to the amusement park yeah that it's
going to do something like
stretch this way and squash that way
squash this way and stretch this way we
do have an
instrument that can detect that kind of
thing
it's called an interferometer
and what it does
is it just basically takes usually light
and the two directions that we're
talking about you send light down one
direction and the perpendicular
direction and if
nothing changes it takes the same and
the arms are the same length it just
goes down bounces back
and if you invert one compared to the
other they cancel so there's nothing
happens
but
if it's like the amusement park and one
of the arms got you know got shorter and
fatter so it took longer to go
horizontally than it did to go
vertically then when they come back when
when the
light comes back that comes back
somewhat
out of time
and that basically is the scheme
the only problem is that that's not
a very done very accurately
in general and we had to do it extremely
accurately so what uh
what what's the what's the difficulty of
uh
doing so accurately okay
so the the measurement that we have to
do
is the distortion in time
how big is it one it's a distortion
that's one part and 10 to the 21 that's
21 zeros and a one
okay wow and this so this is like a
delay in the thing coming back
uh it's a one of them coming back after
the other one but the difference is just
one part and 10 to the 21.
so for that reason we make it big
let it let the arms be long
okay so one part and 10 to the 21.
in our case it's kilometers long so we
have an instrument that kilometers in
one direction kilometers in the other
kilometers we're talking about four
kilometers four kilometers in each
direction
uh
if you take then one part and 10 to the
21 we're talking about measuring
something to
10 to the minus 18 meters
okay
now to tell you how small that is yeah
the proton yeah the thing we're made of
that you can't go and grab so easily is
10 to the minus 15 meters
so this is 1 1000 the size of a proton
that's the effect size of the effect
einstein himself didn't think this could
be measured have we ever seen
actually he said that
but that's because he didn't
you know anticipate modern lasers and
and techniques that we developed
okay
so
maybe can you tell me
a little bit what you're referring to is
ligo the laser uh interferometer
gravitational wave observatory
what is ligo
can you just elaborate kind of the big
picture of you here before i ask you
specific questions about it yeah so
in the same idea that i just said we
have
two long vacuum
pipes
10 to
4 kilometers long okay
we start with a laser beam and we divide
the beam
going down the two arms
and we have a mirror at the other end
reflects it back
it's more subtle but we bring it back
if there's
no distortion in space-time and the
lengths are exactly the same which we
calibrate them to be
then when it comes back if we just
invert one signal compared to the other
they'll just cancel
so we see nothing
okay
but if one arm got a little bit longer
than the other
then they don't come back at exactly the
same time they don't exactly cancel
that's what we
measure
so
to give a number to it
we have to do that
to
we have
the change of length to be able to do
this 10 to the minus 18 meters to one
part in 10 to the 12th and that was the
big experimental challenge that
required a lot of innovation to be able
to do
what you gave a lot of credit to i think
caltech and mit for some of the
technical developments like within this
project
is there some interesting things you can
speak to
like
at the low level of some cool stuff that
had to be solved like what are we yeah
i'm a software engineer so okay all of
this i have so much more respect for
everything done here than anything i've
ever done so it's just code so
so i'll give you
an example of doing uh
mechanical engineering
and a better look at at a basically
mechanical engineering and geology and
maybe at a
level which
okay uh so what do we what's the problem
the problem is the following that i've
given you this picture of an instrument
that i by some magic i can make good
enough to measure this very short
distance
but then i put it down here
it won't work
and the reason it doesn't work is that
the earth itself is moving all over the
place all the time you don't realize it
it seems pretty good to you i get it but
it's moving all the time so somehow
it's moving so much that you we can't
deal with it we happen to be trying to
do the experiment here on earth
but we can't deal with it so we have to
make the instrument
isolated from the earth
oh no
at the frequencies we're at we've got to
float it that's a mechanical that's an
engineering problem not a physics
problem so when you actually like uh
we're doing we're having a conversation
on a podcast right now there's uh and
people who record music work with this
you know how to create an isolated room
and they usually build a room within a
room
but that's still not isolated in fact
they say it's impossible to truly
isolate from sound from noise and stuff
like that
but that that
that's like one step
of
millions that you took
is building a room inside a room because
you basically have to isolate all now
this is actually an easier problem you
just have to do it really well so the
making a clean room is really a tough
problem because you have to put a room
inside a room yeah
so this is this is really simple
engineering or physics uh-huh okay so
what do you have to do how do you
isolate yourself from the from the earth
yes
first we work at
uh we're not looking at all frequencies
for gravitational waves we're looking at
particular frequencies
that you can deal with here on earth
so what frequencies would those be
you were just talking about frequencies
i mean we know by evolution our bodies
know it's the audio band
okay the reason our ears work where they
work is that's where the earth isn't
going making too much noise okay so the
reason our ears work the way they work
is because this is where it's quiet
that's right
so if you go to if you go to one hertz
instead of 10 hertz
it's the earth is
it's really moving around so
so somehow we live in a what we call the
audio band it's tens of hertz to
thousands of hertz that's where we
live that's where we live okay
if we're going to do an experiment on
the earth i might as well do this it's
the same frequency that's where the
earth is the quietest so we have to work
in that frequency so we're not looking
at all frequencies okay
so the solution for the for the shaking
of the earth to get rid of it
is pretty mundane if we do the same
thing
that you do uh to make your car drive
smoothly down the road so what happens
when your car goes over a bump
early cars did that they bounced right
okay but you don't feel that in your car
so what happened to that energy you
can't just disappear energy so we have
these things called shock absorbers in
the car
what they do
is they absorb they take the the thing
that went like that and they basically
can't get rid of the energy but they
move it to very very low frequency
so what you feel isn't
you feel like go shh
smoothly okay
all right so uh
we also work at this frequency so if we
so we basically why
why do we have to do anything other than
shock absorbers so we made
the world's fanciest shock absorbers
okay
not just like in your car where there's
one layer of them they're just the right
squishiness and so forth they're better
than what's in the cars
and we have four layers of it so
whatever shakes and gets through the
first layer we treat it in a second
third
level so it's a mechanical engineering
problem yeah that's what i said so
it's not there's no weird tricks to it
like uh like a chemistry type thing or
no no j