Kind: captions
Language: en
the following is a conversation with
brian greene theoretical physicist at
columbia and author of many amazing
books on physics including his latest
until the end of time mind matter and
our search for meaning in an evolving
universe
this is the lex friedman podcast to
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in the description and now here's my
conversation with brian green
in your most recent book until the end
of time you quote bertrand russell from
a debate he had about god in 1948
he says quote
so far as scientific evidence goes the
universe has crawled by slow stages to
somewhat pitiful result
on this earth and is going to crawl by
still more pitiful stages to a condition
of universal death
if this is to be taken as evidence of
purpose i can only say that the purpose
is one that does not appeal to me i see
no reason therefore to believe in any
sort of god
that's quite a depressing statement as
you say this is a bleak outlook on our
universe and the emergence of human
consciousness so let me ask
what is the more hopeful perspective to
take on the story
well i think the more hopeful
perspective is to more fully
understand
what was driving bertrand russell to
this perspective
and then to see it within
a broader context
and really that's in some sense what
what my book until the end the time is
all about but
in brief i would say that there's a lot
of truth to what bertrand russell was
saying there when you look at the second
law of thermodynamics which is the
underlying scientific idea that's
driving this notion that everything's
going to wither decay fall apart yeah
that's true second law of thermodynamics
establishes that
disorder entropy in aggregate is always
on the rise and that is indeed
interpretable as disintegration and
destruction over sufficiently long time
scales but my view is when you recognize
how special that makes us
that we are these exquisitely ordered
configurations of particles that only
will last for a blink of an eye in
cosmological time like terms the fact
that we're here and we can do what we do
to me
that's just
really something that inspires gratitude
and wonder
and and a sense of of deep
purpose by virtue of being these unique
collections of entities that happen to
rise up look around and try to figure
out where we are and what the heck we
should do with our time
so it's not that i would disagree with
burch and russell
in terms of the
basic
physics and the basic unfolding but i
think it's really a matter of the slant
that you take on what it means for us
so maybe
we'll skip around a bit but let me ask
the biggest possible question then you
said purpose so what's the meaning of it
all then
is uh is there a meaning to life that we
can
take from this
from this brief
emergence of complexity that arises from
simple things and then goes into
a heat death that is once again returns
to simple things as the march of the
second law the thermodynamics goes on i
think there is but i don't think it's a
universal answer
and so i think throughout
the ages there has been
a kind of quest for
some
final way of articulating meaning and
purpose whether it's god
whether it's love whether it's
companionship i mean many people put
forward different ways of
taking this question on
and there is no one right answer when
you recognize deeply
that the universe doesn't care there is
nothing out there
that is the final answer it's not as
though we need a more powerful telescope
and somehow if we can look deeply into
the universe all will become clear in
fact the deeper we've looked both
literally and metaphorically
into the universe and into the structure
of reality the more it's become clear
that we are just a momentary byproduct
of
laws of physics that don't have any
emotional
content they don't have any intrinsic
sense of meaning or purpose
and when you recognize that you realize
that searching for the universal for
this kind of
a question
is a fool's errand every individual has
the capacity to make their own meaning
to set their own purpose and that's not
some platitude that is what we are
because there is no fundamental answer
it's what you make of it and however
much that may sound like a hallmark card
this really is the deep lesson of
physics and science more generally over
the past few hundred years well there's
some level where you can objectively say
that whatever we've got going on here is
kind of peculiar
it's kind of um
special in in in in terms of complexity
and maybe you can even begin
to measure it and like come up with
metrics where
whatever we got going on on earth these
like uh
interesting hierarchical complexities
that form
more and more sophisticated biological
system that seems kind of unique when
you look at the entire universe
the um
the observable part that we can see with
our tools i mean
so i have to ask as you described in
your book once again
uh schroedinger wrote the book what is
life based on the few lectures he gave
in 1944
so let me ask
the fundamental question here
what is
life this particular thing we got going
on here this pocket of complexity that
emerged from such simple things yeah
it's a tough question i asked that
question even to richard dawkins
once
and i already have my preconceived
notion which he pretty much confirmed
which is
if one could give an answer to that
question that allowed you to sort of
draw a line in the sand
between the not living and the living
then perhaps we would have the insight
that we yearn for and trying to say what
is so special about life but the fact of
the matter is it's a continuum there's a
continuum from the things that we would
typically call non-living inanimate to
the things that we obviously call
adamant and full of the currents of life
somewhere in there
it is a question of the complexity of
the structure the ability of the
structure to
take in raw material from the
environment and process it through a
metabolism that allows the structure to
extract energy and to release entropy to
the wider environment
somewhere in those collections of
biological processes is the
necessity or the necessary ingredients
and processes for life but
drawing that line in the sand is not
something that we're able to do but i
would agree with you
it's deeply
peculiar
it may in fact be unique
but it may not it could be that
the universe is such that under fairly
typical conditions a star
that's
a well-ordered source of low entropy
energy that's what the sun is together
with a planet being bathed by that low
entropy energy together with a surface
that has enough of the
raw constituents that we recognize are
fairly commonplace result of supernova
explosions where star
spews forth the result of the nuclear
furnace that is the core of a star it
could be
that all you need are those fairly
commonplace conditions
and maybe life naturally forms like the
james webb space telescope right is
going up hopefully in december and one
of the one of the goals of that mission
is to look at atmospheres around distant
planets and perhaps come to some sense
of how special or not
life or leaf life as we know it is in
the universe
which part of the story of life
let's stick to earth for a second do you
think is the uh is the hardest if you
were like uh
a betting man like which part is the
hardest to uh make happen is it the
origin of life again we haven't drawn
the line of worth
as you say uh the line between a rock
and a rabbit
um
that part is it uh complex organisms
like multicellular organisms
is it uh
crawling out of the ocean where the fish
somehow figured out how to crawl around
is it then the
uh us homo sapiens
as we like to think of ourselves special
and intelligent
uh or is it somewhere in between as you
also talk about
again very hard to know at which point
this consciousness yeah
emerge like if you if you were to sort
of took us
a survey and made bets
about other earth-like planets in the
universe where do you think they get
stuck the most well i would certainly
see if we're going to go all the way to
conscious beings like ourselves i would
put it at the onset of consciousness
which again
i think is a continuum i don't think it
is something that you can draw the line
in the sand but there are obvious
circumstances there are obvious
creatures such as ourselves where we do
recognize a certain kind of
self-reflective conscious awareness
and if we think about what
it would require for a system of living
beings to acquire consciousness
i think that's probably the hardest part
because look
take earth
and recognize that it weren't for you
know some singular event 65 million
years ago where this large rock slams
into planet earth and wipes out the
dinosaurs maybe the dinosaurs would
still rule the planet and
they may well have not developed the
kind of conscious awareness that we have
so
for billions of years on this planet
there was life
that didn't have the kind of conscious
awareness that we have and it was an
accidental event in astrophysical
history that allowed a mammalian species
like us to ultimately be the end product
and so yeah i could imagine there's a
lot of life out there
but perhaps none of it's
wondering what's the meaning of life or
trying to make sense of it
just going about its business of
survival which of course is the dominant
activity that life on this planet has
practice we are a rare exception to that
and i really appreciate that you lean
into some of these unanswerable
questions to me today but the
so you think about consciousness
not as like a phase shift the binary
zero one you think uh
it was a continuum that humans somehow
are maybe some of the most conscious
beings on earth
so you're so
i mean people will dispute that
yes i mean whoa and it's a very hard
argument people will dispute that rocks
probably will stay quiet on the matter
maybe not right for the moment they're
waiting for their opportunity but but
but i i i agree that um look even when
you and i look at each other i
am not fully convinced
that you're a conscious being right i
mean i think that you are on to me i
mean your behavior is such that that's
the best explanation for what's going on
but of course we're all in the position
of only having direct awareness of our
own conscious
being and therefore when it comes to
other creatures in the world we're in a
similar state of ignorance regarding
what's actually happening inside of
their head if they have a head and so
it's hard to know
how singular we are but i would say
based on the best available data and the
best explanations we can make yeah there
is something special about us i don't
think that there are fish walking around
and you know
coming up with you know existentialism i
don't know that there are you know dogs
walking around who've developed an
understanding the general theory of
relativity i mean maybe we're wrong but
that seems the best explanation
what do you think is more special
intelligence or consciousness
i think consciousness and i think that
there's a
deep connection between these ideas they
are distinct but they're deeply
connected but
look i mean to me and to of course many
philosophers actually coined a name for
this the heart problem of consciousness
you know david chalmers and others
as a physicist i look at the world and i
see
it's particles governed by physical law
we can name
them you know we've got
electrons we've got quarks that come in
various flavors and so forth we have a
list of ingredients that science has
revealed
and we have a list of laws that
seemingly govern those ingredients and
and nowhere in there is there even a
hint
that when you put
those particles together in the right
way
an inner world should turn on and it's
not only that there's no hint
it's insane i mean it's ridiculous
how could it be
that a thoughtless
passionless emotionless
particle
when grouped together with compatriots
somehow can yield something so deeply
foreign to the nature of the ingredients
themselves so so answering that question
i think is among the deepest and most
difficult questions that we face
do you
think
it is in fact a really hard
problem
or
is it possible
i think you mentioned your book that
it's just like almost like a side effect
it's an emergent thing that's like oh
it's nice it's like a nice little
feature
yeah well i mean when people use the
phrase hard problem i mean they mean in
a somewhat technical sense that
it's trying to explain something
that
seems fundamentally unavailable to third
party objective
analysis
right i'm the only one that can get
inside my head and i can tell you a lot
about what's happening inside my head
right now it's reflected in what i'm
saying and you can try to deduce things
about what's going on inside my head but
you don't have access to it in the way
that i do and so it seems like a
fundamentally different kind of problem
from the ones that we have successfully
dealt with over the course of centuries
in science where we look at the motion
of the moon everybody can look everybody
can measure it we look at you know the
properties of hydrogen when you shine
lasers on everybody can look at the data
and understand it and so it seems like a
fundamentally different problem and in
that sense it seems like it is hard
relative to the others but
i do think ultimately that the
explanation will be as you recount i
think that a hundred years from now or
maybe it's a thousand it's hard to
predict the time scale for
developments but i think we'll get to a
place where we'll look back and kind of
smile
at
those folks in the 20th century and
before 21st century and before who
thought consciousness was so incredibly
mysterious when the reality of it is
it's just a thing that happens when
particles come together and and however
mysterious that feels right now
i think for instance when we start to
build conscious systems you know things
that you know you're more familiar with
than i am when we start to build these
artificial systems and those systems
report to us
i'm feeling sad
i'm feeling anxious yeah there's a world
going on inside here i think the mystery
of consciousness will just begin to
evaporate well that's
first of all beautifully put and i agree
with you completely just the way you
said it it'll begin to evaporate
i have built quite a few robots and have
had them do emotion
emotional type things and it's immediate
that exactly what you're saying this
kind of mystery of consciousness starts
to evaporate that
the
kind of need to truly understand to
solve the hard problem of consciousness
like disappears because
well
i don't really care
if i understand what can solve the hard
problem of consciousness that thing sure
as heck looks conscious you know i feel
like that way when i interact with a dog
i don't need to
solve the problem of consciousness to to
be able to interact
and richly
enjoy the experience with this other
living being obviously same thing with
other humans i don't need to fully
understand it and there's some aspect
maybe this is a little bit too
engineering focused but there's some
aspect in which it feels like
consciousness is just a
nice trick
to help us communicate with each other
it sounds ridiculous to say but
sort of uh
the ability to experience the world is
very useful in a subjective sense it's
very useful to put yourself in that
world and to be able to describe the
experience to others yeah it could be
just the social and the emerge obviously
animals the sort of more primitive
animals might experience consciousness
in some more primitive way
but this kind of rich
subjective experience that we think
about as humans i think it's probably
deeply coupled like language and poetry
yeah that resonates with my view as well
i mean there's a
scientist maybe you've spoken to michael
graziano from princeton yeah he um
he's developed ideas of consciousness
that look i don't think they solve the
problem but i think they do illuminate
it in an interesting way where basically
we
are not aware
of all the underlying physiochemical
processes that make our brains and our
inner worlds tick the way they do
and because of that dissociation between
sensation and the physics of it and the
chemistry of it and the biology of it it
feels like our minds and our inner
worlds are just untethered like floating
somewhere in this gray matter inside of
our heads
and the way i like to think of it is
like look you know if um if if if you're
in a dark room right and and i had
glow-in-the-dark paint on my fingers so
all you saw was my fingers dancing
around there'd be something mysterious
how how could those fingers be doing
that and then you turn a light you
realize oh there's this arm underlying
it and that's the deep physical
connection explains it all and i think
that's what we're missing the deep
physical connection between what's
happening up here and what is
responsible for it in a physical
chemical biological way and so to me
that at least gives me some
understanding of why consciousness feels
so mysterious because we are suppressing
all of the underlying
science that ultimately is responsible
for it and one day we will reveal that
more fully and i think that will help us
tether this experience to something
quite tangible in the world i wonder
if the mystery
is uh
an important component of enjoying
something
so once once we know how this thing
works
maybe we uh
will no longer enjoy
like this conversation we'll seek other
sources of enjoyment but
there's uh this is again from an
engineering perspective i wonder if the
mystery
is is an important component well you
know there's have you ever seen
there's this beautiful interview that
richard feynman did
you know great nobel laureate physicist
responsible for a lot of our
understanding of quantum mechanics
quantum fields and so forth and he
was in a conversation with an
interviewer where he noted that some
people feel like once the mystery is
gone once science explains something
it
the beauty goes away you know the wonder
if it goes away and he was
emphasizing in his response to that he's
like no that's not the right way of
thinking about he says look when i look
at a rose
he says yeah i can still
deeply enjoy the aroma the color the
texture he says but what i can do that
you can't if you're not a physicist i
can look more deeply and understand
where the red comes from where the aroma
comes from where the structure comes
from he says that only
augments
my wonder it only augments my experience
it doesn't flatten it or take away from
it so
yeah well i sort of take that as a bit
of a
of a motto in some sense that that there
is a wonder that comes from a kind of
ignorance and i don't mean that in a
derogatory sense but just from not
knowing so there is a wonder that comes
from mystery there's another kind of
wonder that comes from knowing
and and and deep knowing and i think
that kind of wonder has its own
special character that in some ways can
be more gratifying
i hope he's right i hope you're right
and but there's also i remember he
he said something about like an
like science is an onion or something
like that you can peel back you can keep
it keep peeling back i mean there is
also
when you understand something there's
always a sense that there's more mystery
to understand
like you never get to the bottom of the
mystery but i think it's also different
than you know
i don't think you can analogize say to a
magician right the magician you know
does some trick you learn how it sounds
like oh my god that was that's
ridiculous when you find but but nature
is perhaps the best magician if you want
to try to make the analogy there because
when you peel things back and you
understand
how it is that things have color and you
have electrons
dancing from one orbital to another
emitting photons at very particular
wavelengths that are described by these
beautiful equations of quantum
electrodynamics part of which that
feynman developed
it gives you a greater sense
of awe when the curtain is pulled back
than what happens in other circumstances
where it does flatten it completely yeah
it's very possible then say in physics
that we arrive at a theory of everything
that unifies the laws of physics and has
a very strong understanding of the
fabric of reality even like from the
very for the big bang to today
it's possible that
that understanding is only going to
elevate our appreciation of this whole
thing yeah i think it will i think it
will i think it has it has so far
but the other side of it which you which
you emphasize is
it's not like science somehow
reaches an end right there are certain
categories of questions that do reach an
end i think we one day we'll close the
book on nature's ingredients and the
fundamental laws now that can't prove
that maybe it goes on forever smaller
and smaller maybe they're deeper and
deeper laws but i i don't think so i
think that there's going to be a
collection of ingredients in a
collection of basic laws that chapter
will close
but
it's one chapter now we take that
knowledge and we try to understand how
the world builds the structures that it
does you know from planets to people to
black holes
to the possibility of other universes
and every step of the way
the collection of questions that we
don't know the answer to only blossoms
and so
there's a there's a deep
sense of gratification from
understanding certain quantities of the
world but i would say that if you take a
ratio
of what we understand to the things that
we know that we don't yet understand
that ratio keeps getting smaller and
smaller because the things that we know
that we don't understand grows larger
and larger
do you have a hope that we solve that
theory of everything puzzle
in the next few decades so there's been
a bunch of attempts from string theory
to all kinds of attempts of trying to
solve quantum gravity or basically come
up with a theory for quantum gravity
there's a lot of uh complexities to this
one for experimental validation
you have to observe effects that are
very difficult to uh measure
so you have to build like that's like an
engineering challenge
and then there's the theory challenge
which is like
it seems very difficult to connect the
laws of gravity to quantum mechanics do
you have a hope or are we
hopelessly stuck well i have to have to
have a hope i mean it's
in some sense but i devote at least part
of my
professional life toward trying to make
progress on i'm glad you use the phrase
quantum gravity
i'm not a great fan of the theory of
everything phrase because
it does make other scientists feel like
if they're not working on this what are
they working on man's like you know
there's not much left when you're
talking about theory of everything
biology is just small d yeah right
exactly
yeah so so it is really trying to put
gravity and quantum mechanics together
and uh since i was a college kid i was
uh deeply fascinated with gravity
and as i learned quantum mechanics the
the notion of physicists being stumped
and trying to blend them together how
could one not get fired up about maybe
contributing something to that journey
and so we've been on this you know i've
been on this for 30 years since i was a
student we we have made progress
we do have ideas you mentioned strength
theory is one possible scenario it's not
stuck string theory is a vibrant field
of research that is making incredible
progress
but we've not
made progress on this issue of
experimental verification validation
which as you know it is a vital part of
the story so i would have hoped that by
now we would have made contact with
observation if you would have
interviewed me back in the 80s when i
was you know a wild bright-eyed kid
trying to make headway working 18 hours
a day on this sort of stuff i would have
said yeah by by 2021 yeah we're gonna
know whether it's right or wrong we'll
make contact i would have said look
there may be certain mathematical
puzzles that we've got to work out but
we'll know enough to make contact with
experiment that has not happened
on the other hand if you would have
interviewed me back then and asked me
will we be able to talk about
detailed qualities of black holes and
understand them at the uh the level of
detail that we actually i i would have
said no i i don't think that we're going
to be able to do that will we have a
an exact formulation of strength here in
certain circumstances no i don't think
we're going to have that and yet we do
so it's just to say you don't know where
the progress is going to happen but yes
i do hold out hope that
maybe before i move on
to wherever i don't think there is an
after but i i would love before i
leave this earth to to know the answer
but
you know science and the universe it's
not about
pleasing any individual it is what it is
and so we just press onward and we'll
see where it goes so in terms of string
theory
if i just look from an outsider's
perspective currently at the theoretical
physics community string theory is the
theory was as a theory has been very
popular for for a few decades but has
recently fallen out of favor or at least
there's been like
you know it became more popular to kind
of
ask the question
is string theory really the answer
where do you fall on this like how do
you make sense of this puzzle why do you
think it has fallen out of favor yeah so
i don't i would actually challenge the
statement that's fallen out of favor
i would say that
any
field of research when it's new and it's
the the bright shiny bicycle that no one
has yet seen on that block yeah it's
going to attract attention
and
the news outlets are going to cover it
and students are going to flock to it
sure but as a as a field matures it does
shed those qualities because it's no
longer as novel as it was when it was
first introduced 30 or 40 years ago
but you need to judge it by a different
standard you need to judge it by
is it making progress on foundational
issues deepening our understanding of
the subject and by that measure string
theory
is is is scoring very high
now at the same time you also need to
judge whether it makes contact with
experiment as we discussed before too
and on that measure we're still
challenged so
i would say that
many strengthers myself included
are are very sober about the theory it
it has the tremendous progress that it
had 30 40 years ago that hasn't gone
away but we've become
better equipped at assessing
the long journey ahead and that was
something that we weren't particularly
good at back say in the 80s look when i
was just starting out in the field
there was a sense of
physics is about to end
string theory is about to be the be-all
and end-all final unified theory and
that will bring this chapter to a close
now i have to say i think it was more
the younger physicists who were saying
that some of the more seasoned even if
they were pro-string theory at the time
i don't know if they were rolling their
eyes but they knew yeah that was going
to be a long long journey i think people
like you know john schwartz one of the
founders of string theory michael green
no relation to me founders of the theory
edward whitton you know one of the main
people driving the theory back then and
today
i think they knew that we were in for a
long haul
and and that's the nature of science
quick hits that resolve everything few
and far between
and so if you were in
for
the
quick
solution to the big questions of the
world then you would have been
disappointed and i think there were
people who were disappointed and moved
on and work on other subjects if we were
in in the way that einstein was in
for a lifetime of investigation to try
to see
where
what the answers to the deep questions
would be then i think string theory has
been a rich source of material that has
kept
so many people deeply engaged in moving
the frontier forward there's a few
qualities about string theory which are
weird
i mean a lot of physics is just weird
and beautiful so let me ask the question
what do you as most beautiful about
string theory well but what attracted me
to the theory at the outset
beyond its putting gravity and quantum
mechanics together which i think is um
it's true claim to fame at least on
paper it's able to do that
what attracted me to here was the fact
that it requires extra dimensions of
space
and this was an idea that intrigued me
in a very deep way even before i really
understood what it meant
i somehow
had i mean talk about sort of the
emotional part of consciousness and the
cognitive part in some perhaps you call
it strange in some strange emotional way
i was enamored with einstein's general
relativity the idea of curved space and
time before i really knew what it meant
it just spoke to me i don't know how
else to say it
and then
when i subsequently learned that people
had thought about more dimensions of
space than we can see and how those
extra dimensions would
be vital to a deep understanding of the
things that we do see in this world four
five six dimensions might explain why
there are certain forces and particles
and how they behave
to me this was like amazing utterly
amazing and then when i learned that
strength theory embraced all these ideas
embraced the general theory of
relativity embraced quantum mechanics
embraced the possibility of extra
dimensions
then i was then i was hooked and so when
i was a graduate student
we would just spend hours
we i mean a couple of other graduate
students and myself who had a have sort
of worked really well together at oxford
in england we would we would work these
enormous numbers of hours a day trying
to understand the shapes of these extra
dimensions the geometry of them what
those geometrical shapes for the extra
dimensions would imply for things that
we see in the world around us
and it was a it was a heady heady time
and and that kind of excitement has sort
of filtered through over the decades but
i'd say
that's really
the the
part of the theory that i think really
hooked me most wrongly
how are we supposed to think about those
extra dimensions i was supposed to
imagine actual physical reality or
is this more in the space of mathematics
that allows you to
sort of come up with tricks to describe
the four-dimensional reality that we
more directly perceive
no one really knows the answer of course
but if i take the most straightforward
approach to string theory you really are
imagining that these dimensions
are there they're real i mean just as
you would
say that the three space dimensions
around us you know left right back forth
up down
yeah we they're real they're here we are
immersed within those dimensions
these other dimensions are
as real as these with the one difference
being their shape and their size
differs from the shape and size of the
dimensions that we have direct access to
through through human experience
and
one approach imagines that these extra
dimensions are tightly coiled up
curled up crushed together if you will
into a beautiful geometrical form
that's all around us
but just too small for us to detect with
our eyes too small for us to detect even
with the most powerful equipment that we
have nevertheless according to the
mathematics the size and the shape of
those extra dimensions leaves an imprint
in the world that we do have access to
so one of the ways that we have hoped
yet to achieve to make contact with
experimental physics is to see a
signature of those extra dimensions in
places like the large hadron collider in
geneva switzerland
and it hasn't happened yet doesn't mean
it won't happen
but that would be
a stunning moment in the history of the
species if data that we acquired in
these dimensions
gives us kind of incontrovertible
evidence
that these dimensions are not the only
dimensions i mean how
mind-blowing would would that be so with
a large header and collider it would be
something in the movement of the
particles or
also the gravitational waves potentially
be a place where you can detect signs of
multiple dimensions like with something
called ligo but much more accurate in
principle all of these can work so one
of the experiments that we had high
hopes for but by high hopes i'm actually
exaggerating one of the experiments that
we
imagined might in the best of all
circumstances yield some insight we
weren't with baited breath waiting for
the result we knew it was a long shot
when you slam protons together at very
high speed as a large hadron collider if
there are these extra dimensions and if
they have the right
form and that's a hypothesis that may
not be correct but when the proteins
collide they can create debris energetic
debris that can in some sense leave our
dimensions and insert itself into the
other dimensions and the way you'd
recognize that is
there'd be more energy before the
collision than after the collision
because the debris would have taken
energy away from the place where our
detectors can detect it so that's that's
one real concrete way that you could
find evidence for extra dimensions but
yeah since extra dimensions are of space
and gravity is something that
exists within in fact is associated with
the shape of space
gravitational waves in principle can
provide a kind of you know cat scan of
of the extra dimensions if you had
sufficient control over
those processes we don't yet but perhaps
one day we will
does it make you sad
a little bit or maybe looking out into
the future you mentioned edwin
that no nobel prizes have been given yet
related to string theory do you think
they will be do you think you have to
have experimental validation or can a
nobel prize be given which i don't think
has been given for quite a long time
for uh
purely sort of theoretical contributions
yeah it certainly as a matter of
historical precedent has been the case
that those who win the prize
have
established investigated
illuminated a demonstrably real quality
of the world
so
gravitational waves the prize was
awarded after they were detected not not
the mathematics of it but the actual
detection of it you know the higgs
particle
you know it was an idea that came from
the 1960s peter higgs and others in fact
and it wasn't until
on july 4th when the announcement came
that this protocol had been detected the
large hadron collider that people viewed
it as eligible for the nobel prize the
idea was there the math was there but
you needed to
confirm it indeed the prize ultimately
was awarded so i'm not surprised
in fact i would have been surprised if a
nobel prize had been awarded in the
arena of string theory because it's far
too
speculative right now it's far too
hypothetical in fact
i am sympathetic to the view
that it really shouldn't be called
string theory it degrades the word
theory
because theory in science of course
means the best available explanation for
the things that we observe in the world
the things that we measure in
experiments about the world
and string theory does not do that at
least not yet so it really should be
the string hypothesis right we're at an
earlier stage of development
and that's not the kind of thing that
nobel prizes should be awarded for
what do you think about the critics out
there peter white he's from colombia too
i think sabine hafenstadter
is that a healthy thing or should we
sort of focus on sort of the optimism of
of these hypotheses yeah
it's actually a good way that you frame
it
because
i'm always
somewhat repelled
by
views of the world
that start from the negative
try to cut down an idea try to say
that's the wrong way of thinking about
things and so on i'm
much more drawn maybe because i'm an
optimist i don't know i'm much more
drawn to those who go out into the world
with new ideas yeah and and don't try to
cut down one idea but rather present
another one that might be better
and so you make the first idea maybe
strengthy irrelevant because you've come
up with the
better approach to the world
so do i think it's healthy look i think
having a wide
range of
views and perspectives is generally a
healthy thing
i think it's good to have
arguments within a subject in order that
you stay fresh and you stay focused on
the things
that matter but in the end of the day i
think it's a more
vital contribution to give us something
new rather than to criticize something
that's there yeah i'm totally with you
um but it could be just the nature of
being an optimist i and also just a
a love of engineering it's there's it it
helps nobody by criticizing
the uh the rocket that somebody else
built just build a
bigger cheaper better rocket
exactly yeah and that seems to be how uh
human civilization can progress
effectively
we we've uh mentioned the second law of
thermodynamics i got to ask you about
time
yeah and
do you do you think of time as emergent
or fundamental to our universe i like to
think of it as emergent
i don't
have a solid reason for that perspective
i have a lot of hints of reasons that
some of which come out of string theory
and quantum gravity that perhaps would
be worth talking about
but what i would say is
time is
the most familiar quality of experience
because there's nothing that takes place
that doesn't take place within an
interval of time and yet at the same
time
it is perhaps the most mysterious
quality of the world so it's a wonderful
confluence of the familiar and the
deeply mysterious all in one little
package
if you were to ask me what is time
i don't i don't really know i don't
think anybody does i i can say
what time gives us
it allows us the language for talking
about change
it allows us to envision the events of
the universe being spread out in this
temporal timeline and in that way
allows us to see the patterns that
unfold within time i mean time allows us
the structure and the organization to
think about things in that kind of a
progression but
what actually is it
i i don't really know and that's so
strange because
we can measure it
right i mean there are laboratories in
the world that measure this thing called
time to spectacular precision
but you know if you go up to the folks
and say like
what is it that you're actually
measuring
i don't know that they can really
articulate the kind of answer that you
would expect
from those who are engineering a device
that can measure something called time
to that level of precision
so it's a very curious combination
what do you make of the one-way
feeling of causality like is causality
a thing or is that too just a human
story
that we put on top of this emerging
phenomena of time i don't know
um i can give you my my guess and my
intuition about it
i do think that at the macroscopic level
if we're talking about sort of the human
experience of time i do think at the
macroscopic level there is a fundamental
notion of causality that does emerge
from a starting point that may not have
causality built in so i certainly would
allow that at the deepest
description of reality when we finally
have that on the table
we may not see causality directly at
that fundamental level but i do believe
that we will understand how to go from
that fundamental level to a world where
at the macroscopic level there is this
notion of a causes b
a notion that einstein deeply embraced
in his special theory of relativity
where he showed that time has qualities
that we wouldn't expect based on
experience you and i if we move relative
to each other our clocks
tick off time at different rate and our
clocks is just a means of measuring this
thing called time so this is really time
that we're talking about time for you
and time for me are different if we're
in relative motion he then shows in the
general theory of relativity that if
we're experiencing different gravity
different gravitational fields or
actually more precisely different
gravitational potentials
time will elapse for us at different
rates these are things that are
astoundingly strange that give rise to a
scientific notion of time travel okay so
this is this is how far einstein took us
in
wiping away the old understanding of
time and injecting a new understanding
of its qualities so so there's so much
about time that's counterintuitive
but i do not think that we're ever going
to wipe away causality at the
macroscopic at the microscope i mean
there's so many interesting things at
the macroscopic level that may only
exist at the microscopic level yeah like
we already talked about consciousness
that that very well could be one of the
things you mentioned time travel so
um
i mean according to einstein
and
in general
what
types of travel do you think our
physical universe allows well certainly
allows
time travel to the future and i'm not
talking about the silly thing that you
and i are now going into the future
second by second second i'm talking
about really the diversion that you see
in hollywood at least in terms of its
net effect whereby
an individual
can follow an einsteinian
strategy
and
propel themselves
into the future in some sense more
quickly so if if i wanted to see what's
happening on planet earth 1 million
years from now
einstein tells me how to get 1 million
years from now build a ship i got to
turn to guys you know who know how to
build stuff i can't do it like you build
a ship that can go out into the universe
near the speed of light
turn around and come back let's say it's
a six month journey out a six month
journey back and einstein tells me how
fast i need to travel how close to the
speed of light i need to go so that when
i step out of my ship
it will now be one million years into
the future on
planet earth
and this is not
a controversial statement right this is
not something where there's differences
of opinion in the scientific community
any scientist who knows anything about
what einstein taught us agrees with what
i just said it's it's commonplace it's
bread and butter physics and so that
kind of travel to the future is
absolutely allowed by the laws of
physics there are engineering challenges
they're they're technological challenges
close to the speed of light yeah yeah
and they're they're even biological
challenges right they're g-forces that
you're going to experience you know so
there's all sorts of stuff embedded in
this but those
i will call the details and those
details
notwithstanding
the universe allows this kind of travel
to the future and if i could pause real
quick
you could also
at the macro level
with biology extend the human lifespan
to do a kind of
travel forward in time
if you expand how long we live yeah
that's a way to from a perspective of an
observer a conscious observer that is a
human being
you're essentially traveling forward in
time by allowing yourself to live long
enough to see the thing yes so that's in
the space of biology
uh what about traveling back in time
yeah that's the um
that is a natural next question
especially if you uh if you're doing if
you're going on one of these journeys is
it a one-way journey yeah can you can
you come back
and
the physics community doesn't speak with
a unified voice on this as yet but i
would say that the dominant perspective
is that you cannot get back
now having said that there are proposals
that serious people have written papers
on
regarding hypothetical ways in which you
could travel to the past and
we've seen some of these again hollywood
loves to take the most sexy ideas of
physics and build narratives around them
this idea of a wormhole like jody foster
and contact went through a wormhole
deep space nine star i'm sure there are
many other examples where these ideas
that i've probably never even seen
but with wormholes there's at least a
proposal of how you could take a
wormhole tunnel through space-time
manipulate the openings of the wormhole
in such a way that the openings are no
longer synchronous they are out of sync
relative to each other which would mean
one's ahead and one's behind which means
if you go through one direction you
travel to the future if you go back you
travel to the past
now
we don't know if there are wormholes
possible according to einstein correct
they are possible according to einstein
but even einstein was very quick to say
just because my math allows for
something doesn't mean it's real and he
famously didn't even believe in black
holes yeah didn't believe in the big
bang right and yet the big the the black
hole issue has really been settled now
we have
radio telescopic photographs of the
black hole in m87 who's in newspapers
around the world just a couple of years
ago so
so it's just to say that just because
it's in einstein's math um it doesn't
mean it's real but yes it is the case
that wormholes are allowed by einstein's
equations and in principle
you can imagine you know putting
electric charges on the openings of the
wormhole allowing you to toe them around
in a manner that could yield this
temporal asymmetry between them maybe
you toe one of the mouths to the edge of
a black hole in principle you can do
this slowing down the passage of time
near that black hole and then when you
bring it back it will be well out of
sync with the other opening and
therefore could be a significant
temporal gap between one and the other
but people have studied this in more
detail questioned could you ever keep a
wormhole open assuming it does exist
could you ever travel through a wormhole
or would there be a requirement of some
kind of exotic matter to prop it open
that perhaps doesn't exist so
there are many many issues that people
have raised and i would say that the
general sentiment
is that it's unlikely
that this kind of scenario is going to
survive our deeper understanding of
physics when we finally have it but that
doesn't mean that the door is closed so
maybe it's a
a small possibility that this could one
day be ready that's such an interesting
way to put it
it will not this kind of scenario will
not survive deep understanding of
physics
it's an interesting way to put it
because
it makes you wonder what kind of
scenarios
will be created by our deeper
understanding of physics maybe
uh
sorry to go crazy for a second but if
you have like the pan psychosome idea
that
consciousness permeates all matter maybe
traveling in that whatever laws of
physics the consciousness operates under
something like that in that view of the
universe if we somehow are able to
understand that part maybe traveling is
super easy yeah
it does not follow the constraints of
the speed of light
something like this yeah so
look i have i have a definite
degree of um
sympathy with the possibility
that consciousness might be more than
what we described earlier is just the
byproduct of mindless particles you just
made the rock happy
exactly you know so so
it isn't the approach that
feels to me the the most likely but i i
see the logic
if you've got the puzzle how do mindless
particles build mind one resolution
might be the particles are not mindless
the particles have some kind of
proto-conscious quality so there's
there's something appealing about that
straightforward solution to the puzzle
and if that's the case if we do live in
a pan-psychist world where there's a
degree of consciousness residing in
everything in the world around us then
yes i do think some
interesting possibilities might emerge
where maybe there's a way of communing
with physical reality
in a in a deeper way than we have so far
i mean we as human beings a vital part
of our existence is human to human
communication contact we live in social
groups and that's what it's allowed us
to get to the place where we've gotten
imagine
that we have long missed that there's
other consciousness out there and some
kind of relationship or communion with
that larger conscious possibility would
take us to a different place now do i do
i buy into this yet i don't i don't see
any evidence for it
but do i have an open mind and allow for
the possibility in the future yeah i do
so if that's not the case and you have
these
simple particles that at the macro level
emerges some interesting stuff like
consciousness another thing you write
about in the until the end of time book
is the the thing that seems to emerge at
the macro level is the feeling
like uh that like there's a free will
like we decide to do stuff and you have
a really interesting take here
which is
no there's not a free will i'm just
going to speak for you and then you
should correct me no there's not a free
will
but there is
an experience of freedom yeah
yeah
which i i really love so where does the
experience
where does freedom come from if we don't
have any kind of physics based free will
yeah and and so the idea
follows naturally from all that we've
been talking about let's make the
assumption
that all there is in the physical
universe is stuff governed by laws we
may not have those laws may may not know
what the fundamental stuff is yet
but everything we know in science points
in the direction that it's physical
stuff governed by universal laws
and
that being the case or that being the
assumption then you come to a particular
collection of those ingredients called a
human being and that human being has
particles that are fully governed by
physical law
and when you then recognize that every
thought that we have every action that
we undertake is just the motion of
particles when i'm thinking thoughts
right now of course at this level of
description it is the motion of
particles cascading down various neurons
inside of my head and so on and every
single one of those motions collectively
and individually is fully governed by
these laws that we perhaps don't have
yet but we imagine one day we will that
leaves no opportunity for any kind of
freedom to break free from the
constraint of physical law and that is
the end of the story
so the traditional intuitive notion of
free will that we're the ultimate
authors of our actions that we were the
buck stops that there is no antecedent
that is the cause for our decided to go
left or right choose vanilla or
chocolate live or die
that intuitive sensation does not have a
basis in our understanding of the
physical world so that's the end of the
free will of the traditional sort but
then your question is
what a