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  • Now, on NOVA,

  • take a thrill ride into a world

  • stranger than science fiction,

  • where you play the game by breaking some rules,

  • where a new view of the universe

  • pushes you beyond the limits

  • of your wildest imagination.

  • This is the world of "string theory,"

  • a way of describing every force and all matter

  • from an atom to earth, to the end of the galaxies --

  • from the birth of time to its final tick,

  • in a single theory, a "Theory of Everything."

  • Our guide to this brave new world

  • is Brian Greene, the bestselling author and physicist.

  • BRIAN GREENE (Columbia University):

  • And no matter how many times I come here,

  • I never seem to get used to it.

  • NARRATOR: Can he help us solve

  • the greatest puzzle of modern physics --

  • that our understanding of the universe

  • is based on two sets of laws that don't agree?

  • NARRATOR: Resolving that contradiction eluded even Einstein,

  • who made it his final quest.

  • After decades,

  • we may finally be on the verge of a breakthrough.

  • The solution is strings,

  • tiny bits of energy vibrating

  • like the strings on a cello,

  • a cosmic symphony

  • at the heart of all reality.

  • But it comes at a price:

  • parallel universes and 11 dimensions,

  • most of which

  • you've never seen.

  • BRIAN GREENE: We really may live in a universe

  • with more dimensions than meet the eye.

  • AMANDA PEET (University of Toronto): People who have said that there

  • were extra dimensions of space

  • have been labeled crackpots, or people who are bananas.

  • NARRATOR: A mirage of science and mathematics

  • or the ultimate theory of everything?

  • S. JAMES GATES, JR. (University of Maryland):

  • If string theory fails to

  • provide a testable prediction,

  • then nobody should believe it.

  • SHELDON LEE GLASHOW: (University of Boston)

  • Is that a theory of physics,

  • or a philosophy?

  • BRIAN GREENE: One thing that is certain is that string theory

  • is already showing us that

  • the universe may be a lot stranger

  • than any of us ever imagined.

  • NARRATOR: Coming up tonight...

  • GABRIELE VENEZIANO (CERN): We accidentally discovered string theory.

  • NARRATOR: ...the humble beginnings

  • of a revolutionary idea.

  • LEONARD SUSSKIND (Stanford University):

  • I was completely convinced it was going to say,

  • "Susskind is the next Einstein."

  • JOSEPH LYKKEN (Fermilab): This seemed crazy to people.

  • LEONARD SUSSKIND: I was depressed, I was unhappy.

  • The result was I went home and got drunk.

  • NARRATOR: Obsession drives scientists to pursue the Holy Grail of physics,

  • but are they ready for what they discover?

  • Step into the bizarre world of the Elegant Universe right now.

  • THE ELEGANT UNIVERSE

  • Hosted By Brian Greene

  • String's the Thing

  • Two Conflicting Sets of Laws

  • BRIAN GREENE: It's a little known secret

  • but for more than half a century

  • a dark cloud has been looming

  • over modern science.

  • Here's the problem:

  • our understanding of the universe

  • is based on two separate theories.

  • One is Einstein's general theory of relativity --

  • that's a way of understanding

  • the biggest things in the universe,

  • things like stars and galaxies.

  • But the littlest things in the universe,

  • atoms and subatomic particles,

  • play by an entirely different set of rules

  • called, "quantum mechanics."

  • These two sets of rules

  • are each incredibly accurate in their own domain

  • but whenever we try to combine them,

  • to solve some of the deepest mysteries in the universe,

  • disaster strikes.

  • Take the beginning of the universe,

  • the "Big Bang."

  • At that instant

  • a tiny nugget

  • erupted violently.

  • Over the next 14 billion years

  • the universe expanded and cooled

  • into the stars,

  • galaxies and planets we see today.

  • But if we run the cosmic film in reverse,

  • everything that's now rushing apart

  • comes back together,

  • so the universe gets smaller,

  • hotter and denser

  • as we head back to the beginning of time.

  • As we reach the Big Bang,

  • when the universe was both

  • enormously heavy and incredibly tiny,

  • our projector jams.

  • Our two laws of physics,

  • when combined,

  • break down.

  • But what if we could unite

  • quantum mechanics and general relativity

  • and see the cosmic film in its entirety?

  • Well, a new set of ideas

  • called "string theory"

  • may be able to do that.

  • And if it's right,

  • it would be one of the biggest blockbusters

  • in the history of science.

  • Someday, string theory may be able

  • to explain

  • all of nature,

  • from the tiniest bits of matter

  • to the farthest reaches of the cosmos,

  • using just one single ingredient:

  • tiny vibrating strands of energy

  • called strings.

  • But why do we have to rewrite

  • the laws of physics

  • to accomplish this?

  • Why does it matter

  • if the two laws that we have

  • are incompatible?

  • Well, you can think of it like this.

  • Imagine you lived in a city

  • ruled not by one set of traffic laws,

  • but by two separate sets of laws

  • that conflicted with each other.

  • As you can see

  • it would be pretty confusing.

  • To understand this place,

  • you'd need to find a way

  • to put those two conflicting sets of laws together

  • into one all-encompassing set that makes sense.

  • MICHAEL DUFF (University of Michigan):

  • We work on the assumption

  • that there is a theory out there,

  • and it's our job, if we're sufficiently smart and sufficiently industrious,

  • to figure out what it is.

  • STEVEN WEINBERG (University of Texas at Austin):

  • We don't have a guarantee --

  • it isn't written in the stars

  • that we're going to succeed --

  • but in the end

  • we hope we will have a single theory

  • that governs everything.

  • BRIAN GREENE: But before we can find that theory,

  • we need to take a fantastic journey

  • to see why the two sets of laws we have

  • conflict with each other.

  • And the first stop on this strange trip

  • is the realm of very large objects.

  • To describe the universe on large scales

  • we use one set of laws,

  • Einstein's general theory of relativity,

  • and that's a theory of how gravity works.

  • General relativity pictures space

  • as sort of like a trampoline,

  • a smooth fabric that heavy objects

  • like stars and planets

  • can warp and stretch.

  • Now, according to the theory,

  • these warps and curves create

  • what we feel as gravity.

  • That is, the