'The Fabric of the Cosmos'

DATE March 16, 2004 ACCOUNT NUMBER N/A
TIME 12:00 Noon-1:00 PM AUDIENCE N/A
NETWORK NPR
PROGRAM Fresh Air

Interview: Physicist Brian Greene talks about some of the concepts
from his new book.
TERRY GROSS, host:

This is FRESH AIR. I'm Terry Gross.

David Greene's new book begins with a number of provocative questions: Does
time have a beginning? What does it mean for space to be empty? Can we
manipulate space and time? What is reality? Greene is a physicist who has
become well known for his ability to clearly explain some of the most
challenging concepts of physics. He's also famous within his field for his
discoveries in superstring theory. His book about string theory, "The Elegant
Universe," became a best seller. His new book, already a best seller, is
called "The Fabric of the Cosmos: Space, Time and the Texture of Reality." It
explains how modern science is revising our picture of reality, offering new
theories about the world that exists beyond what we can perceive with our
senses.

You start the first chapter of your book not by quoting Einstein or Newton but
by quoting Camus. And you quote something he says at the beginning of the
"The Myth of Sisyphus," which is, `There is but one truly philosophical
problem, and that is suicide. Why did you start your book on space and time
and string theory with that quote about suicide?

Mr. BRIAN GREENE (Physicist/Author): Well, that particular quote I read when
I was a teen-ager, and it really had a big influence on me because it very
clearly in very stark language lays out what the most important question that
we can ask ourselves is, and that's the question: Is life worth living?
Should we carry on on this journey that we have been set upon?

And in the years since reading that quote, it has really kind of framed the
work that I've done, because I've always felt that you can't answer that
question, that key question, if you don't know what the context within which
life takes place actually is. That is, if you don't know what the universe
is, you don't really know what life is and you don't know what is valuable in
life. So I, for many years, have been trying to figure out, with many
colleagues around the world, you know, how the universe came to be, how it
takes the form that we witness on a dark, starry night. In that way, just
trying to get as clear a picture of the framework within which life takes
place.

GROSS: Now what I love about your book, which I also find very unbalancing,
is that your writing makes me disbelieve my senses because, as you say, the
reality we observe may have little to do with the reality that's out there.
So you're dealing with things that are way beyond our senses, in part, because
they're so micro, micro, microscopically small.

Mr. GREENE: Yeah. I mean, that's really what science has been doing for the
last 50 or 100 years. I mean, there was a time, if you go back to the time of
Newton, when the key questions had to do with things that you do see in
everyday life. You know, Newton apocryphally was looking at, you know, apples
falling from trees or the motion of the moon around the Earth, things that you
could see with your eyes. But, basically, the success that we've had at
describing everyday phenomena using the laws of physics has impelled us,
driven us to go further.

And when we have gone further to try to understand the microscopic structure
of matter, molecules and atoms and subatomic particles, the shocking thing is
research has revealed that the familiar world operates according to principles
that just don't apply in the microworld. The microworld is very bizarre.
It's very strange and it kind of morphs into the familiar everyday world when
things get larger. But if you or I were to live in the microworld, if we were
to shrink our bodies by a factor of 100 million, billion and walk around in
the microworld, it would be more bizarre than any science fiction that you've
ever seen. It is very odd and very strange by everyday standards.

GROSS: Let's get back to the idea that the reality we observe may have little
to do with the reality that's out there, and let's apply that to time. Now my
reality is that my watch ticks away time second by second and that time, in my
reality, is always moving forward. It never moves backward except in memory.
And it moves forward in predictable ways, in 24-hour days, although some days
seem longer and some days feel shorter, depending on how well the day is
going.

OK, but scientists have challenged this idea of the forward arrow of time.
What is the theory that challenges that time just moves forward in a
predictable way?

Mr. GREENE: Well, scientists haven't completely challenged the idea that
time has a forward arrow associated with it. What they have puzzled over,
though, is something tightly related to that, which is why does it have a
forward arrow associated with it? I mean, after all, for instance, space,
you're able to move left or right; you can move back or forth. You seem to
have complete freedom to navigate space. Why don't you have the same freedom
to navigate time? Why does time seem to relentlessly point toward what we
conventionally call the future?

Now the strange thing is that when you study the laws of physics, there's no
orientation when it comes to time that is fundamentally embedded in the laws
of physics. In other words, the future and the past, according to the
equations that Newton wrote down or the equations that Einstein wrote down or
the equations of quantum theory, all of those equations treat past and future
on completely equal footing, completely symmetrically, but yet, our experience
is completely asymmetric. The past is behind us and gone; the future is yet
to be. This is our intuition. Where does that experience come from if the
laws of physics don't seem to have an arrow of time built into them?

That's the question that we have studied, and we've made a lot of progress, I
think, in trying to come to an answer. The surprising thing--We can go
through the chain of reasoning, if you'd like--is that the reasoning leads us
to the big bang itself. We believe that special conditions at the birth of
the universe imprinted a direction on time, and we have been living through
the unfolding of that arrow of time that was lost, if you will, by the big
bang itself.

GROSS: Well, do you think about things like time travel, like if we'll ever
be able to move forward in time and see the future before the future happens
or move backward in time and visit the past?

Mr. GREENE: Well, time travel is a very provocative idea, and it really is
very important to distinguish between two kinds of time travel: time travel
to the future and time travel to the past. And the reason why you need to
make that distinction is time travel to the future is not part of science
fiction. It really emerges from insights that Einstein had in the early part
of the 20th century. Time travel to the future is within the laws of physics
as we understand it.

If you want to see what, say, the earth will be like 1,000 years from now or
10,000 or even a million years from now, Einstein lays out a strategy for
doing it. You build a spaceship, you travel out into space at very high
speed, near the speed of light, you turn around and you come back. And if
you've carried out that journey correctly, when you return to Earth, perhaps
one year will have elapsed according to your biology and according to the
clocks in your ship, but when you step out of your spaceship, 1,000 years or
10,000 or a million years will have gone by on Earth. You will have leaped
into Earth's future through this particular journey.

Now we can't actually build the ships that can go near the speed of light, so
we can't actually carry out this kind of journey today or perhaps ever; I
don't know. But in terms of the laws of physics, traveling to the future is
absolutely within those laws.

Now travel to the past...

GROSS: Yeah, what about traveling to the past?

Mr. GREENE: Well, that's, of course, the key thing. Let's say, you know,
somebody gives you the opportunity and you do travel to the future, can you
get back? And most of us believe that you can't. Most of us believe that
time travel to the past is just on a very different par than travel to the
future. You know, the reason is something that we're all very familiar with.
There are all sorts of paradoxes that arise if you can travel to the past.
You know, you can imagine traveling to the past and doing something that would
prevent your own birth. Then how are you there to actually carry out that act
if you were never born in the first place? There are paradoxes of this sort.

Now these paradoxes--it turns out there are ways around them, some very cute
and interesting ways around them, from quantum theory in particular. But our
gut feeling is that when the laws of physics are fully understood, time travel
to the past will not be possible. But I should say, you know, as of today,
some very well-respected physicists have even suggested ways that you might
build a time machine that would allow you to travel to the past. When you
study the proposals in detail, they seem to all kind of brush right up against
the limits of the currently known laws of physics. Most of us believe that
when those laws are better understood, the proposals will actually pierce them
and step outside the laws of physics and thereby be impossible. But as of
today, no one's been able to prove that. And that's at least kind of
compelling and provocative.

GROSS: My guest is physicist Brian Green. His new book is called "The Fabric
of the Cosmos." We'll talk more after a break. This is FRESH AIR.

(Soundbite of music)

GROSS: My guest is physicist Brian Greene. His new best seller is called
"The Fabric of the Cosmos: Space, Time and the Texture of Reality."

Since your new book is about time and space, let's talk a little bit about
space. We think of space--we lay people think of space as being empty, you
know, just kind of like devoid of anything, maybe like there's air or there's
not air or there's some particles floating around. But how do you think of
space? Do you think of it as emptiness or something else?

Mr. GREENE: Yeah, very different. This is one of the key ways in which, I
think, common perception misleads us. And maybe as an aside, I should
emphasize, I don't think it's surprising that common perception will mislead
us, because our perceptions evolved through many centuries, through many
millennia in order that we can survive in the jungle. And perceptions that
are good at making us survive are not necessarily good at revealing the true
nature of the world, the true nature of the universe. That's why we need to
go further with our minds and experiments and our equations.

And when we do that, especially with regard to space, we come to a very
different picture of space than the intuitive one that you just described,
because--for instance, according to quantum mechanics and this so-called
Heisenberg uncertainty principle, which is a principle that says that there
are always features of the microworld that are undetermined, that can
fluctuate between various possibilities, and what that means when you apply it
to space is that there is no such thing as truly empty space. Even in what
you normally think of as the deep darkness of empty space: no planets, no
stars, no galaxies, totally dark, quantum theory says that there's always, in
the microscopic feature of that space, particles popping into existence and
then annihilating, fields, like the electromagnetic field, fluctuating up and
down. So in the microworld, there is this tumult, this chaos, this frenzied
activity that even happens in the deep darkness of what we normally think of
as completely empty space. So the very notion of nothingness is completely
rewritten by the laws of quantum physics.

GROSS: Well, you know, if the world is filled with dimensions that our senses
don't allow us to perceive, you could argue that, you know, some or all of
those dimensions are the world of microparticles. But I guess you could also
argue just as easily that that world is a more spiritual one in which we see,
you know, spiritual forces that--in which there exists spiritual forces that
we are incapable of perceiving.

Mr. GREENE: Yeah, I would dissuade people from heading in that direction.
Let me tell you why. Indeed, string theory is the theory that I work on, one
of the cutting-edge developments in an attempt to build what Einstein called a
unified theory, a theory that might describe everything in the world using one
basic master equation. And this approach called string theory does entail
that the universe have more than three dimensions that we know about. So we
all know about left, right, back, forth, up, down. This theory does say that
there are other dimensions beyond those. And since we don't see them, many
people might say, `Well, perhaps they are on par with some of the mystical
ideas or theological ideas.'

And the main difference and the key distinction to keep in mind is when we
talk about these extra dimensions, we ultimately--we haven't been able to do
it yet, but we ultimately imagine that we'll make predictions for how these
dimensions behave and the implications that these dimensions have for
observable phenomenon. And that's the key difference between the scientific
incarnation of these strange ideas and the mystical incarnation. We only will
believe these ideas when we can test them experimentally. There's no active
faith that's going to be involved in our taking on the theories that we are
studying. And I don't think that's true of either the theological or mystical
approaches which always, as far as I have encountered so far, involve some
element of faith and a key inability to make predictions that will be testable
and allow us to determine whether those ideas are right or wrong.

GROSS: What's wrong with faith? What's wrong with just believing something
because you have faith, even though it isn't empirically provable or testable?

Mr. GREENE: Nothing's wrong with it at all. In fact, my brother is a Hare
Krishna. And for many years, the developments that we've come upon in physics
and string theory--I always enjoy telling him about these developments. And a
lot of times, he'll say to me, `Well, we already knew that. That's in Vedic
text number 23 or something of that sort.' And, you know, it's an interesting
exchange because when we've ever gone into more detail on it, it seems as
though many of the ideas that we have come upon do have a kind of resonance
with ideas that have been articulated in ancient text or even in more modern
theological or mystical text.

And I think that's very interesting. But from the point of view of what we
really believe as true from the scientific perspective, we have laid down over
the last few centuries a particular yardstick to determine what we believe and
what we don't believe. And from the scientific point of view, that yardstick
involves making a prediction, then an experiment you can go out and measure
and determine whether your prediction is right or wrong. If your prediction
is confirmed, your ideas are right; if your prediction is not borne out by the
experiment, your ideas are plain wrong. And we have found this to be a very
fruitful way to describe the universe. We have got very deep ideas which are
now describing the world and able to make predictions.

Now it's not to say that that yardstick is the right one outside of science.
You know, when it comes to religion and mystical ideas, maybe faith is the
right yardstick. But the key thing to bear in mind is you're not going to be
able to really make a prediction. You're not going to be able to say how the
universe truly works if you're not, at least as far as I've seen in any
example, working in the scientific context where experiment is the yardstick.

GROSS: Do you think that science necessarily conflicts with religion and vice
versa?

Mr. GREENE: Not at all. I mean, oftentimes people do talk about this
conflict between science and religion. And, look, if you want to stop
teaching evolution and start teaching creationism, then, yeah, there's a
conflict. But I don't consider the over-arching realms of science and
religion to be in conflict because, for instance, it could be that everything
that I'm doing as a scientist and everything that every other scientist is
doing is simply revealing the laws that were laid down by some divine being.
This is absolutely possible. In fact, if you think about it, there's no way
ever for science to disprove that possibility because the retort can always
be, `Well, the divine being set it up so that you'd describe things and make
that argument to try to disprove what the divine being set in place.' So it's
completely unfalsifiable that what we're doing might be revealing God's
design. And to tell you the truth, if that's what we're doing, I think it's
pretty cool. I'd be very excited to spend my life trying to work out the laws
that the divine being set down.

Now I should say, I see no evidence for a divine being. I see no evidence for
anything but the laws of physics. And, again, if there is no divine being and
what we're doing is revealing laws that have described how the universe began
and how it's going to evolve for 100 billion years into the future, I think
that's pretty cool, too, and I'm excited to try to work out those laws unto
themselves.

GROSS: What's your reaction to the people who believe that evolution should
not be taught in the schools but creationism should or that creationism should
be taught alongside evolution or that something called intelligent design
should be taught? And if I comprehend intelligent design correctly, that is
the theory that the universe is so complicated that there had to be some kind
of master intelligence behind it. And the implication at least is that that
master intelligence is God. So what's your reaction to that whole conflict?

Mr. GREENE: Yeah. Well, I find it highly unfortunate and very dangerous
when one tries to substitute religious ideas for scientific breakthrough and
scientific developments. Again, you know, I think if one is taking a course
on religion and theology, then I think it's very interesting to study what the
ancient religions have said about the universe and how it came into being and
so forth. But my own feeling is--and I think this is shared by many people;
at least I hope it is--that science has given us such new deep insight into
the workings of the world. I mean, we can understand, by and large, how it is
that the universe is expanding. We can understand, by and large, how it is
that galaxies form, how stars form. We understand the nuclear processes that
allow our sun to shine and bathe the Earth in radiation and heat and light.
And to try to substitute something for the powerful science that we've
developed to understand these things is a travesty.

Again, you know, I feel that it's not the point of science to rule out that
perhaps everything we do fits inside some religious context, but no way should
we allow older religious ideas to somehow displace the fantastic developments
that science has achieved over many years.

In fact, let me just say it this way. There's a way of thinking about
religion where, when you can't address something in the natural world, you try
to bring in God or some religious explanation because you haven't yet figured
it out. And that is often called God of the gaps. We use God to fill in the
gaps in our understanding. And from that point of view, the more we
understand, the more God is necessarily going to get pushed out. The more we
understand how the world came to be and how life evolved and formed, we're not
going to need the theological explanations. And I think there are some people
who feel that religion is diminished by being pushed out from that explanatory
role.

But what we as scientists will never do is give an answer to why there is a
universe and the meaning of the universe and the meaning of life. And I think
that many people--not me, but many people do find religion is very, very
effective at answering those `why' questions. So my feeling is, we should use
science in the realm that science works well to answer the `how' questions,
and we should perhaps, if it's one particular taste, use religion to answer
the `why' questions.

GROSS: Brian Greene is the author of the new best seller "The Fabric of the
Cosmos: Space, Time and the Texture of Reality." He'll be back in the second
half of the show. I'm Terry Gross, and this is FRESH AIR.

(Soundbite of music)

GROSS: This is FRESH AIR. I'm Terry Gross back with physicist Brian Greene,
author of the new best-seller "The Fabric of the Cosmos: Space, Time and the
Texture of Reality." It discusses the latest scientific theories about the
nature of space, time and the reality beyond what we can perceive with our
senses. It explains many complicated ideas but can't answer how I got this
annoying cold. Fortunately, we recorded the interview before I came down with
it. Anyway, when we left off, we were comparing how science and religion go
about explaining some of the same questions about the nature of the universe.

As a physicist is very interested in the creation of the universe and
implications of the big bang theory, can you talk a little bit about the
creation story from the physicist's point of view?

Mr. GREENE: Yes. So from the point of view of physics, the creation
story, if we use that language...

GROSS: Right. Yeah.

Mr. GREENE: ...it is often described as the big bang. And the key thing that
many people are not aware of is that the big bang is a theory of how the
universe evolved from a split second after whatever occurred to bring it into
existence. And we definitely are still struggling to figure out what happened
at time zero. Our equation's general relativity breaks down when we try to
apply it literally to time zero itself. We can only go far back as about, you
know, a fraction of a second--you know, 10 to the -43 seconds--after the
beginning. And that's where our story begins; we don't start at the very,
very start.

And the idea is that in the very beginning the universe, all of space, all of
time, in fact, it was all compressed to an ultra-microscopic nugget, very,
very tiny. Now this is not a nugget that exists within space. This is all of
space crushed together. Then the universe begins to expand. Space expands;
it goes outwards. And as the universe expands, it cools down. It was very
hot in the beginning. It gets cooler and cooler and cooler as space expands.
And as it cools down, structures can begin to congeal out of this primordial
hot plasma. And that structure begins to form, and its yields ultimately
galaxies and stars. And other things form out of the plasma, planets and,
ultimately, the things that we see on our Earth. So there are a lot of
mathematical details in that progression over 14 billion years, but that's, in
a nutshell, our understanding of how the universe takes the form that it
currently does.

GROSS: It's so difficult to imagine the whole universe being a kind of
particle. Not a particle within the universe, but the whole universe is that
one particle.

Mr. GREENE: Yeah.

GROSS: And then you start wondering, `Well, what's around the particle?'

Mr. GREENE: Yeah, it's a very natural question.

GROSS: And if there's nothing around the particle--it's just kind of
unfathomable. I can't...

Mr. GREENE: It's very hard because...

GROSS: Yeah.

Mr. GREENE: ...you're right, I mean, any object that we look at exists within
space...

GROSS: Exactly. Exactly.

Mr. GREENE: ...and, therefore, there's space around it. And what we are
asking you to do is to imagine that all of space itself is crushed to this
very, very small size, so that there wouldn't necessarily be anything outside
of it. You know, it's very hard to picture.

Analogies sometimes help. I don't know if this one will do it for you, but we
often invoke the so-called balloon analogy, where we imagine that all of space
is the surface of a balloon. Now for this analogy to work, you can't think
about what's in the balloon, outside the balloon. Think of the surface of the
balloon as the entire universe. And when the balloon is very, very, very
tiny, space will, therefore, be very small. As you begin to blow air into the
balloon, the balloon will expand and to get bigger and bigger. And that
expansion is quite analogous to the expansion or stretching of space.

Now the surface of the balloon gets bigger and bigger without it necessarily
requiring a realm to expand into. Now that's hard to picture because we
always think of the balloon in a room, and it's getting bigger within the
room. But imagine that the surface of the balloon is everything. There's
nothing else in this balloon universe but its surface. And as its surface
stretches, you get more balloon, more space. Similarly, as our universe
expands, you get more space. It doesn't require pre-existing space. The
expansion itself creates the new space itself.

GROSS: You've co-discovered a couple of big things in the world of physics.
Would you tell us about one of them, maybe the one that's simpler to explain?

Mr. GREENE: Sure. I've worked for many years on the spatial dimensions that
string theory requires. And I came upon something a couple of years ago which
is very interesting, very exciting. So in Einstein's general relativity, as
we've sort of discussed already, the theory says that space can expand. In
fact, it says other things. It says space can stretch, it can twist, it can
warp, it can undergo all sorts of changes in shape over time. But the one
thing that general relativity says cannot happen, it says that space can't
rip. Now if you take any familiar piece of material, you stretch it enough,
it will tear. General relativity says that's a failure of the analogy; that
when it comes to space, you can keep on stretching and it will never rip.

Now we studied this question in string theory, which is a theory that goes
beyond Einstein's general theory of relativity by also incorporating quantum
mechanics. And we reasked that question: Can space rip? And in the
framework of string theory, we found that, indeed, space can tear. Space can
literally rip apart without there being any catastrophe, without there being
any explosion or anything like that. Space can rip and repair itself in a
manner that Einstein would not have thought possible. So, in essence, what we
learned is that space can evolve through a sequence of changes that are much
more exotic than the ones that Einstein would have thought possible in the
20th century.

GROSS: So if space rips, what does that mean exactly? Like, if a fabric
rips, you can stick your finger through it.

Mr. GREENE: Yeah.

GROSS: If space rips, what gets through the space? What's on one side of the
tear, and what's on the other side of the tear?

Mr. GREENE: Yeah, it's a very good question because you might say, `Well, if
it rips, is the space in between the two pieces--is that part of the universe,
or is that outside of the universe?' And the answer is that there isn't any
`in between' the two pieces because, again, we're talking about the entire
universe, we're talking about all of space. And what we're simply learning is
that the changes in the shape of space are more exotic than what we've thought
before. So were you at the edge of the rip, so the speak, it's not as though
you could fall out into some abyss. No, it just means that that piece of
space would be connected to a different part at the end of this process than
it would have been connected to at the start of this process. So it's simply
an evolution in the shape of space that previously would have been ruled out
but now is allowed by these more refined laws of string theory.

GROSS: My guest is physicist Brian Greene. His new book is called "The
Fabric of the Cosmos." We'll talk more after a break. This is FRESH AIR.

(Soundbite of music)

GROSS: My guest is Brian Greene. His new best-seller is called "The Fabric
of the Cosmos: Space, Time and the Texture of Reality." Greene is a
physicist who has made discoveries in the area of string theory.

Can I ask you to give us a layperson's explanation of what string theory is?

Mr. GREENE: Yeah, sure. Absolutely. So string theory--well, first, let me
just say what it attempts to do, and then I'll say what the theory actually
is. String theory attempts to realize the dream that Albert Einstein himself
articulated in 1930s, 1940s, of finding this unified theory, what he called
it, the single theory, to describe everything. And at that time Einstein was,
really, kind of, oh, somewhat of an outcast among scientists because no one
else really believed that this was a worthy goal or it was a goal that was
attainable. So he kind of worked in solitude for many years. It was a very
sort of sad end to the career of the perhaps greatest physicist of all time
because he worked very hard to find this unified theory, but he never found
it.

Now we think that string theory, this new approach, may well be the theory
that Einstein was looking for, a theory that does unify everything together.
Now how does it do that? Well, the basic question that string theory seeks to
address is: What is the smallest constituent making up matter in the world
around us? So just to be concrete, imagine you took a piece of wood and you
sliced it in half; slice that piece in half again, keep on cutting into
ever-smaller pieces. And the natural question is: Where does it stop, or
does it stop? Is there a finest ingredient that you get to in this cutting
process? Now we've learned in our age that sooner or later in this cutting
process you get way down to the scale of molecules and atoms. But we also
have learned that atoms are not the end of the story because they can be cut,
they can be split, into little electrons that orbit around the nucleus, which
has neutrons and protons. And even those particles can be split up because
they have finer constituents that are known as quarks.

Now that is where conventional theory and experiment stops. Electrons and
these little particles called quarks and a few other exotic species are the
fundamental entities making up everything: you, me, tables, everything in the
world that we can literally see. String theory comes along and says no. It
suggests that the story continues. It suggests that there's at least one more
level of structure. So it says that if you were to look inside an electron or
look inside a quark, you would see something else, and the something else is a
little filament, little filament of vibrating energy. It kind of looks like a
string; that's where the name string theory comes from. And the wonderful
idea is that just as the string on a violin...

(Soundbite of music)

Mr. GREENE: ...can vibrate in different patterns that your ear will hear,
different musical notes, these little strings in string theory also can
vibrate in different patterns. The vibrations don't produce music. Instead,
they produce the different particle species. So an electron is a string
vibrating, say, like a middle C, and a quark is a string vibrating like an A.
So everything in the world, according to string theory, comes from one
fundamental idea: the vibrations of these little strings, these little
filaments of energy. That's the basic idea.

GROSS: And somehow the discover or the posing of this string theory leads to
the possibility that there are other dimensions beyond the dimensions that we
are capable of perceiving.

Mr. GREENE: Yes.

GROSS: How does string theory lead to the possibility of other dimensions?

Mr. GREENE: Very tough question to answer it without mathematics, so let me
just say it briefly, and then I'll maybe just fill it in with more of a
technical statement. But the underlying mathematics of string theory says
that the math breaks down, it doesn't make sense, unless these strings can
vibrate in a certain number of patterns. Now imagine you have a little string
on your tabletop. It can vibrate in, say, the left, right and back-forth
dimensions on the tabletop, but that's it if you constrain it to vibrate only
on the surface of the table. Now allow the string to also vibrate in the
up-down direction. Clearly there'll be more vibrational patterns that can be
executed: the ones that you had before, plus these new ones that might go in
the up-down direction.

Now the thing is when we count up the number of vibrational patterns in the
universe with three dimensions, there aren't enough to satisfy the equation of
string theory. When we look in a universe that, say, has four dimensions,
indeed, now we have more vibrational patterns. It's hard to picture, but the
more dimensions there are, the more vibrational patterns there are allowable.
There aren't enough in four dimensions to meet the equations of string theory.
We keep on going. And, finally, when we hit the 10-dimensional universe, the
number of vibrational patterns of a string does match the requirement that
comes out of the math of string theory. And that's where we get this strange
prediction that the universe doesn't have three dimensions, but it has more.
It comes from the internal mathematical consistency of the equations of the
theory itself.

GROSS: Well, I think all I could say to that is wow (laughs).

Mr. GREENE: Yeah. Well, I have to tell you that's what physicists said.
This was completely unexpected. People were studying the physics of strings,
and they came upon this equation. And the equation, for the time, I should
say, in the history of physics was not an equation for some process in the
universe. It was an equation that dictated the number of dimensions of space.
And the absolute mind-blowing, strange thing was when people studied the
equation, it did not say that there are three dimensions of space. It said
there are more. And that was very, very unexpected and very mind-blowing.

GROSS: What are the tools that you use to pose questions about another
dimensions?

Mr. GREENE: Well, we do thought experiments. We can't, at the moment, build
technology that would actually allow us to probe these extra dimensions,
again, assuming the theory is correct, so we pose thought experiments. We ask
ourselves, `Imagine that the extra dimensions have a particular shape. Think
of it as a ball or a doughnut or any particular shape that the equations
allow.' And we ask ourselves, for instance, `What would happen if the shape
of the extra dimensions were to slowly change? Would there be something that
we could observe in the world around us that would change in a corresponding
manner?' And, indeed, we have found, for instance, that the massive particle,
like the electron, would slowly shift if the extra dimensions change their
shapes slowly, or the strength of the electromagnetic force or the strength of
gravity might slowly shift if these extra dimensions changed. And we spent
many years trying to make a very precise dictionary between the shapes of
these extra dimensions and the physics of the particles that we would observe.

If you like, I can spell that out a touch more concretely.

GROSS: Sure.

Mr. GREENE: When a string vibrates, its vibrational pattern, as I was saying,
determines the properties of particles. So, for instance, the string vibrates
really fast, it has a lot of energy. And from Einstein's E=MC2, that means
the corresponding particle would have a lot of mass. If a string vibrates
very gently, the energy will be less, so the particle will have less mass and
so forth. Now when a string vibrates, it doesn't just vibrate into the three
dimensions around us. A string is so tiny that it also vibrates into the
extra dimensions. And just as the air that goes through a French horn goes
into vibrational patterns that are influenced by the twists and turns in the
French horn, the vibrational patterns of a string are influenced by the twists
and turns in the geometry of these extra dimensions. And that means that
properties in the world around us, like the mass of the electron or the
strength of the forces of nature, may well be determined by the shape of the
extra dimensions. So it's not a matter of hiding away the extra dimensions,
making them very small because we can't see them. They may have a very direct
impact on the world around us.

GROSS: What did you fall in love with first? A search for, like, meaning in
the world or just a passion for numbers and the beauty of numbers themselves?

Mr. GREENE: It was definitely numbers. You know, when I was a little kid, I
was amazed by the fact that--you know, my dad taught me the elementary
operations: addition, you know, division, multiplication and so forth. And I
was amazed by the fact that with these few rules, you could then start to do
stuff. You could do calculations, maybe a calculation that nobody had done
before. And I think that's, really, what's very compelling about numbers and
about mathematics. I mean, you see it--we are aware of there being, you know,
mathematical prodigies, but do you ever have a prodigy in history or
psychology or English literature? No, because those subjects you require
maturity, you require experience to excel. But in mathematics, you teach a
kid a few operations, and he or she can go off and running and do stuff. And
that's what I did as a kid.

You know, I started to do these calculations that my dad would set me maybe to
keep me out of his hair or something. And I would spend days and days doing
these huge multiplications and complications, often for no real purpose beyond
the wonder of the numbers themselves.

GROSS: Now your father was or is a former vaudevillian? Do I have that
right?

Mr. GREENE: Yeah. Yeah. My dad was a...

GROSS: What was his act?

Mr. GREENE: Well, he used to be part of a harmonica act when he was much
younger. He was also a...

GROSS: Not the Harmonicats?

Mr. GREENE: No, no. It was a much less-well-known group. And he was also a
stand-up comedian. He was also a voice teacher. He was Harry Belafonte's
vocal coach actually. So Harry Belafonte would often come to our apartment in
Manhattan when I was growing up to take lessons. So it was a very musical
environment when I was growing up. But it was also a difficult one because, I
mean, as you know, as many people know, the music industry is very hard to
succeed. And my dad, who spent much of his time composing--and he wrote a lot
of music that never saw the light of day. And it was hard to see this very
talented, creative person, whose work basically just would gather dust. So it
was very hard in many ways.

GROSS: Are you interested in the physics of music? You know, the vibrations
of notes and instruments and all that?

Mr. GREENE: Well, I love the fact that--the analogies that physicists have
used for many years, which are often musical.

GROSS: Right.

Mr. GREENE: You talk about the music of the spheres. You talk about, you
know, vibrations and so forth. The fact that these metaphors are--they find
their most natural home in string theory, you know, the theory that I work on,
because the strings in string theory--the equations really are very similar to
the equations of a violin string. I mean, there are sort of key differences,
but roughly speaking they're in the same genre of equations. And the fact,
therefore, that the analogy of music really brushes up so closely to the
physics I discuss and work on is very satisfying. It sort of brings it all in
a full circle for me.

GROSS: Well, I'd like to end on a note about string theory, getting back to
the idea that string theory allows for the possibility--in fact, suggests the
possibility--that there are other dimensions beyond our perception. Could you
just, like, leave us with some idea of what one of those dimensions might be
or how these extra dimensions might affect us, if at all, once we discover
them?

Mr. GREENE: Yeah. Well, if the extra dimensions are of the sort that we
think about, I think that they may give an answer to what many people think is
the deepest question that a scientist can ask, which is this: Why is the
universe as it is? So experimenters for a hundred years have gone out and
measured the numbers that I mentioned before, like the mass of the electron or
the strength of gravity, the strength of the electromagnetic force. And there
are about 20 numbers of that sort that very, very talented experimenters have
measured. We have the numbers, and we can write them down. The thing is
nobody knows why the particular numbers have the values that they do. We
don't know why the electron weighs what it does. Now you might say, `Who
cares? You know, if it weighed a little more, it weighed a little less, so
be it. That's just how the world would be.'

But you really should care because it turns out that if you change any of
those numbers by even a little bit, the universe as we know it would
disappear. The universe has stars which rely upon nuclear processes that
demand delicate relationships between those numbers. You fiddle with those
numbers, you change the nuclear processes, they don't happen, stars don't
light up, the universe as we know it blacks out. It completely disappears.
So the deep question is: Why do the 20 numbers have just the right values to
allow stars to shine, planets to form and people to exist on at least one
planet? Now no theory has answered this question; string theory hasn't. But
it has proposed a framework, and the framework relies upon the extra
dimensions because, as I mentioned before, string vibrations, we believe, are
the answer to why those numbers have the value they do. The strings vibrate
into the extra dimensions. So if we knew exactly what the extra dimensions
looked like--we don't know them yet, but if we did, we might be able to
calculate how the strings would vibrate and that way calculate the 20 numbers.

And if the answer that we got for those 20 numbers agreed with the numbers
that experimenters have found over the last century, that really would be the
first fundamental explanation for why the universe is as it is and it would
rely upon the extra dimensions. So that really is what we're shooting for:
trying to explain how it is that the world around us takes the form that it
does. And it may very well invoke those extra dimensions in string theory.

GROSS: Well, Brian Greene, thank you (laughs). Very interesting (laughs).
Thanks for talking with us.

Mr. GREENE: Thank you. I enjoyed it.

GROSS: Brian Greene is the author of the best-seller "The Fabric of the
Cosmos: Space, Time and the Texture of Reality."

Coming up, Lloyd Schwartz reviews the Alloy Orchestra's new scores for Buster
Keaton silent films. This is FRESH AIR.

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

Review: Alloy Orchestra's music for silent movies
TERRY GROSS, host:

Silent movies were never really silent. They were always accompanied by
music. Most of the original music has been lost. One of the pioneers in
composing new music for old movies is the Alloy Orchestra. Classical music
critic Lloyd Schwartz thinks they do just about everything music for a silent
movie needs to do and more.

(Soundbite of music)

LLOYD SCHWARTZ reporting:

A few weeks ago I was part of a sold-out crowd having the time of its life at
a silent movie, a screening of Buster Keaton's great Civil War comedy "The
General." Part of the attraction was the live accompaniment perfectly
synchronized by the amazing Alloy Orchestra, a group that both composes and
performs its own music. This orchestra is actually a trio: Terry Donahue on
junk percussion and accordion, Roger C. Miller on synthesizer and Ken Winokur
playing percussion and clarinet. They provide atmosphere--comic, romantic or
ominous--and especially changes of mood. They also provide sound effects: a
train whistle, a bird call, a marching band, a rifle shot. They can reinforce
a sight gag or underline the punch line of a joke: ba-da-boom.

Two of the Alloy Orchestra's best scores are for Buster Keaton's masterpieces
"The General" and "Steamboat Bill Jr." "The General" is one of the most
complexly ironic treatments of American heroism in film. The title is the
name of a train run by the Keaton character, Johnny Gray, a Confederate Army
rejectee. He's good at his job, not only competent but imaginative. Yet he's
also a klutz, who can be most successful when he's most inept. At one point
he pulls his sword out of its sheath, and the blade comes loose and flies into
the air. But when it lands, it kills his most dangerous enemy. Without
diminishing the comedy, the music is also truly heroic, evoking the grandeur
and tragedy of the Civil War in what was the closest Keaton came to producing
an epic. The merging of the two main themes, the riveting train music and the
visceral war music, is chilling.

(Soundbite of music)

SCHWARTZ: One of the great Keaton moments comes in "Steamboat Bill Jr." A
hurricane is ravaging the town. Keaton is standing in front of a house when
the whole front wall collapses on him. Miraculously, he's standing directly
under an open window. Keaton was legendary for doing his own stunts. The
wall could have killed him if it landed only inches to the left or right. In
some screenings, though, that two-ton wall doesn't look very heavy. Maybe
because the film speed is a little off. If the wall comes down just the
slightest bit too fast or too slow, it seems weightless. On the new DVD from
Image, the projection speed has been corrected, and the Alloy Orchestra
provides just the subtlest little drum thud when the falling wall hits the
ground. I've never seen a version in which the weight of the wall, the danger
to Keaton, is so completely realized.

(Soundbite of music)

SCHWARTZ: Most silent movie music just fills the void. Some of it even gets
in the way. But the Alloy Orchestra really helps us see what we're watching.
And often the music, whether driving or fanciful, is even worth listening to
on its own.

GROSS: Lloyd Schwartz is classical music editor of The Boston Phoenix. He
reviewed the Alloy Orchestra, which can be heard accompanying silent movies on
DVDs released by Image Entertainment and Keyno(ph). In the next few months
the Alloy Orchestra will be performing in Detroit, Boston, Winston-Salem,
Baltimore and New York and at the Ozark Foothills Film Festival, the San
Francisco Film Festival and Roger Ebert's Overlooked Film Festival.

(Soundbite of music)

(Credits)

GROSS: I'm Terry Gross.
Transcripts are created on a rush deadline, and accuracy and availability may vary. This text may not be in its final form and may be updated or revised in the future. Please be aware that the authoritative record of Fresh Air interviews and reviews are the audio recordings of each segment.