Saturday, May 13, 2006

Space, the Final Frontier

The Beginning of Time: String Theory

I've been reading The Elegant Universe, Brian Greene's wonderful book on string theory. A quick description quoted from the publishers comments on the back cover:
"In a rare blend of scientific insight and writing as elegant as the theories it explains, Brian Greene, one of the worlds leading string theorists, and author of the forthcoming the Fabric of the Cosmos, peels away layers of mystery surrounding string theory to reveal a universe that consists of eleven dimensions, where the fabric of space tears and repairs itself and all matter - from the smallest quarks to the most gargantuan supernova - is generated by the vibrations of microscopically tiny loops of energy.

This was my third reading and each time I came away with a deeper insight of quantum theory and a sense of awe that mankind can even conceive of such a far reaching theoretical description of the universe. The universe as something as opposed to nothing, not just a universe of stars, but corporeality itself.

At the beginning of the last century physics was relatively simple, matter was viewed in a way similar to the Greek concept of atoms. Of course scientists, being a curious lot, found a way to break apart the atom into smaller particles, neutrons, protons and electrons, but it didn’t stop there and particle smashing became a part of experimental physics for the next century.

As one might suspect, experimental physicists kept finding more and more subatomic particles, the little pieces which made up the atomic particles, quarks, muons… and things became complicated rather quickly. Up to this point we are still using a model we can easily visualize by playing around with some styrofoam balls. Consider the photon, the particle for light, and everything goes awry. Light sometimes behaves like a waveform, this can be verified by experiment but it is also can be viewed as a particle which also can be tested by experiment. In 1927, Werner Heisenberg and Niels Bohr proposed the Uncertaity Principle which in essence states that you cannot measure properties which define both states at the same time. Things are now starting to become interesting, as these chameleon like properties, become evident only when viewed statistically, sometimes they are here, sometimes they are there, but if you measure them, you freeze a particular state.

Richard Feynman was awarded the Nobel Prize for physics for his work on Quantum electrodynamics which offers a solution to the problem above by suggesting that light takes all possible paths to its destination and what the scientist observes is the statistical sum of all of them. Right about here one has to leave a common sense world view behind, welcome to quantum physics. As counter-intuitive this seems in a Newtonian world view , it was a theory which helped make, among other things, the transistor possible. However, in spite of the early achievements in quantum theory, there were several unexplained questions and all the macro-micro views did not all quite fit together, in particular Gravity was problematic. In physics, one often finds big theoretical problems are caused by mathematical solutions which give "undefined" results, like dividing a number by zero. Infinity is the bane of the mathematical theorist. For example, when a star collapses into a black hole its density, mass/volume, which might shrink to zero, becomes infinite. While this may not be precisely correct, it does describe one of the problems which occurs when trying to formulate an all inclusive quantum theory, the holy grail of physics, the TOE, the theory of everything.

Enter string theory
In 1968, theoretical physicist Gabriele Veneziano was trying to understand the strong nuclear force when he made a startling discovery. Veneziano found that a 200-year-old formula created by Swiss mathematician Leonhard Euler (the Euler beta function) perfectly matched modern data on the strong force. Veneziano applied the Euler beta function to the strong force, but no one could explain why it worked.
In 1970, Yoichiro Nambu, Holger Bech Nielsen, and Leonard Susskind presented a physical explanation for Euler's strictly theoretical formula. By representing nuclear forces as vibrating, one-dimensional strings, these physicists showed how Euler's function accurately described those forces.

Brian Green picks it up from there, leading the reader through the historical developments as well as the mind boggling mathematical and conceptual constructs which make string theory a viable possibility for a TOE.

String theory, or M-Theory as it is now called, is an appealing conceptualization which piqued my interest in several areas. For one, a string, as far as I can understand, isn't anything at all. It is not really a "thing" or made of something, rather it is a vibration in space, if it ceases to vibrate, like a guitar string it is silent, it ceases to exist. If it vibrates, it possess energy and since energy and matter are related, it becomes something.

In order to keep the bookkeeping straight, eliminate those pesky infinities and to unify all the forces including gravity, Edward Witten and others proposed an 11 dimensional space to contain reality as we know it. The expanded dimensions, three space dimensions, plus the time dimension are what we experience, the other seven dimensions are described as being "curled up", or super small. Visualizing 11 dimensions is wickedly difficult, the mathematicians can describe them mathematically, but trying to visualize them is more or less impossible. I think it is possible to understand their implications, they allow the strings to exist and as such they allow the world to exist.

So I asked myself, what was there before the big bang? Nothing? I like the idea of nothing. So suppose we have nothing, by nothing I mean nothing, no space, no time, nothing. "Let there be space" and there was space. The will of a supreme being, or just chance, that is all it would take, because once there is space, everything else follows. Since strings require space, but are not made from space, they just vibrate in space, the shock of the initial creation of space sets everything into vibration, the vibration creates energy and matter, and must expand. Something from nothing, it's a start, the grand inflation leading to the separation of the primary forces, gravity and matter, it is all just space buzzing at one frequency or another. What a grand idea.

1 comment:

Anonymous said...

Before the big-bang there was a flat 10d space.
This answer was provided by Veneziano himself
in the 90's in a series of papers.