The Music of the Spheres
Date: Friday, March 26 @ 18:06:29 UTC
What a gorgeous idea, guaranteed to stir the soul of every poet, every mystic, every musician: everything that is is made from invisible (so far) vibrating strings of energy. A cosmic symphony, of which we and everything we know is but one infinitesimal note. The drive in physics to find the one 'theory of everything,' the one organizing principle governing the universe, is of course our human religious impulse expressed in mathematics, the sacred language of physics. This yearning for a unity of understanding is the impetus behind all religious expression over the entire history of humanity. Our most ancient ancestors after all knew what Isaac Newton showed mathematically: that the same laws which rule over the earth rule everything in the cosmos, and that whatever God is, so too are we.
The earliest deities in Africa were stellar gods and goddesses. Somehow we understood when we looked to the sky that those glowing and twinkling things up there were our origin, our home, and the source of all our sustenance. Cosmologists showed us that indeed we are who we are, right here, right now, doing what we do only because primeval stars exploded and made us. We are literally stardust, the 15 billion years' expression of the cataclysmic instant when everything we can conceive of came into being, merely the latest effect of the great Cause, with many many more to come. Everything that is is united in a vast stream of history that ripples out from that one defining moment.
We are the first creatures we know of to understand ourselves, with the power to reflect on this history, to glimpse the whole of this grand tapestry, and that gives us a unique place in this story. It can be said that the universe knows itself through us, and that in our celebration of the universe, the universe celebrates itself. This also gives us a unique and grave responsibility. We know that everything that is exists on the razors' edge between creation and obliteration, and unlike the galaxy that birthed us (for when we look at the Milky Way, She is in the truest sense our mother), we have choices here in our little blue microcosm. Immense violence is our heritage but it need not be our legacy. We are an astonishing cosmic development indeed.
Albert Einstein was a religious man. The search that consumed him all of his life, and made him appear to some in his later years as a doddering old fool, refusing to accept the idea of quantum chance, was for a unified field theory, one explanation for the four great cosmic forces: gravity, electromagnetism, and the strong and weak nuclear forces. Einstein felt and knew that there was one explanation for everything under heaven and earth, and that human beings were capable of discovering it. This is no less than the search for God.
When Isaac Newton watched the apple fall from that tree, he had his revelation of 'gravity.' He realized that the same force which caused the apple to fall caused the planets to stay up. He saw gravity as a force from the Sun that grabs the earth and determines its obit. His equations were so powerful that they launched satellites and got us to the moon. Gravity to him is a force that acts instantaneously and across great distances, across any distance. His equations show with great accuracy how the planets move. And the idea implied in these equations, the idea of simultaneous action at a great distance and not dependent on time, made Newton himself uncomfortable.
Einstein's equations showed something different, that it takes time for the effect of one thing to be known in another location. The velocity of light is a cosmic speed limit, and not even gravity can travel faster. It takes 8 minutes for the sun's rays to reach the earth. So how then do the planets stay up? According to Newton, if the sun were destroyed the planets would immediately lose their orbits and go flying out into space.
Einstein's theory of General Relativity gives the answer. Gravity is not a giant tractor beam, but what we experience as gravity are warps and curves in the fabric of space and time. We live in four dimensions, three dimensions of space and one of time. All things move along the surface of space and time, and like balls rolled onto a rubber sheet, or wind along the surface of a pond, the weight of planets and stars warp the surface of space-time as they move along it. The earth follows the curve made by the sun's presence, and this is what we experience as gravity. If the sun were destroyed, this would cause a series of waves like ripples on water, and nothing would happen to the earth until the waves reach it. 8 minutes. Gravity travels at the speed of light. In just the same way, galaxies were formed by 'density waves.'
Next, Einstein wanted to understand the relationship between gravity, and the other known primal force at the time, electromagnetism. It was James Clerk Maxwell who showed that electricity and magnetism are not separate forces. The problem for Einstein was that gravity is billions of times weaker than electromagnetism, so how are they related? The reason why a person who jumps off a skyscraper doesn't simply go crashing through the sidewalk to the center of the earth is because of the repelling action of the electrons of the sidewalk meeting the electrons of the falling body. It will just make a little dent. A little patch of sidewalk can repel the full force of the earth's gravity.
The question for Einstein was how to unify these principles? To complicate the issue further, two more primal forces were discovered, the strong and weak nuclear forces. The strong nuclear force is the bond between protons and neutrons that holds the nucleus of an atom together. The ultimate testament to the almost inconceivable strength of this force is what happens when it is forcibly broken. This is the nuclear reaction, and no one has to be reminded of the immense force of that. The sun derives its energy from constant nuclear fusion reactions. The weak nuclear force is when neutrons are converted into protons. This is radioactivity, a product of the strong force. Niels Bohr also discovered that, when looking at the behavior of elementary particles, particles far smaller than atoms, these 'quanta', both gravity and electromagnetism were far too weak to account for any of what he was seeing. The fabric of space is bumpy and chaotic on the quantum level. Space and time are utterly distorted, and all 'laws' simply break down. He said that on the quantum level, uncertainty rules, and only the laws of mathematical probability make any sense. It may be that all possibilities for the effect of an action do occur in parallel universes. Einstein reacted angrily, saying, 'God does not play dice with the universe.' It was his dearest and deepest belief that there is a way to explain everything. In most physicists' minds, Einstein simply could not keep up with the times.
General Relativity is an elegant theory, smooth, orderly, and geometric, and absolutely accurate when it comes to the formation and movements of stars and galaxies. Just as quantum mechanics is amazingly accurate in its domain of the subatomic. But what of the moment of creation, the Big Bang, when something extremely tiny erupted violently and over the last 15 billion years expanded and cooled into the universe as we know it? Here the two theories conflict.
And there is the black hole. When enormous mass and density are concentrated in a small space, space-time is warped so severely that not even light can escape its gravitational pull. How do you explain what goes on in a black hole? With relativity because the star that forms it is so immensely heavy, or with quantum mechanics because the star that forms it is so infinitesimally tiny? Since it is both, both theories if they have any validity must somehow apply. Since atoms and galaxies belong to the same universe, there must be some way to describe both. Relativity describes gravity. Quantum mechanics describes electromagnetism and the strong and weak nuclear forces. The reaction of the 4 forces with matter describes everything in the universe. But how do the four forces relate to each other?
And so, we come to the string. Instead of tiny particles, perhaps all matter is composed of one thing-tiny vibrating strands of energy. Maybe the ways they vibrate, the ways they wiggle, represent all the kinds of elementary particles: the protons, neutrons, electrons, quarks, photons, gravitons, gluons… Just as violin strings vibrate at different frequencies and create different sounds, the 4 forces are a reflection of changes in mass and force due to the strings' oscillation patterns.
What frightened physicists for some time is that the equations of string theory require extra dimensions of space. Einstein theorized that the warps in space time caused by gravity might constitute a fifth dimension. Newton's universe is a flat, static, unchanging grid. Einstein said space can warp and stretch. String theorists have found a way that space can even safely tear. Strings on the quantum level calm the chaos and can surround a tear, making wormholes possible, which could mean that we may one day find a way to travel vast distances in space without being limited by the speed of light.
For the equations of string theory to make sense there have to be at least 11 dimensions. But it is even possible that there is an extra curled-up dimension at every point in space. Because I am not a mathematician, I cannot even begin to conceive of what this means. But it is the extra dimensions that allow strings to wiggle the way they do, and allows them, with enough energy, to stretch into membranes, membranes as large even as the universe itself. This is the picture of the universe that emerges: perhaps our universe is living on a membrane inside a multi-dimensional space. It's like we are one slice of a loaf of bread. And our picture of the universe may be limited by the fact that we are trapped on just this single slice. Other slices are parallel universes, existing in other dimensions all around us.
The reason string theorists aren't laughed out of the town is the explanatory power of strings, the 'beauty' of these equations. For the last 100 years, no one has been able to integrate gravity into a unified theory. Quantum mechanics does well integrating electromagnetism and the strong and weak nuclear forces, but how to account for the weakness of gravity compared to the other forces? Electromagnetism is 10 to the 39th power stronger than gravity. Think of it: with our muscles we overcome the entire force of the gravity bearing down on our planet. Instead of asking why gravity is so weak, string theorists assume its great strength and ask why we don't experience it. Maybe atoms and particles stay on our membrane, while gravity slides off our part of the universe into other dimensions. Maybe some strings are open-ended, with one end tied down to our 3-D membrane, while others are closed-loop strings that can move from dimension to dimension. Physicists call this gravity-carrier a graviton, and huge atom-smashers and particle accelerators have been constructed to search for it. Giant atom-smashers strip the electrons off atoms and send the protons shooting down a 4-mile track at speeds approaching the speed of light. When two protons, collide, subatomic particle showers result, and scientists hope some day soon to discover the trail of a graviton escaping to another dimension. Maybe we can feel the other dimensions of our being through gravity. Maybe we will be able to use gravity waves to communicate across parallel universes.
String theory also shows promise in explaining some of the problems with our idea of the Big Bang, the cataclysmic explosion that brought this universe as we know it into being. Something unimaginably tiny and unimaginably dense for no reason we can determine exploded, and from that moment to this the universe has expanded and expanded into something unimaginably huge. This idea accounts for so much, but the laws of physics break down at that moment of explosion-none of the math we have makes sense. But string theory asks, what if the Big Bang is the result of the collision of two membranes, of two of these parallel universes, these slices of bread? If strings were present at the Big Bang, they would have stretched out and expanded like everything else, so physicists have hope that we will someday find traces of one.
It is interesting to hear mathematicians speak of beauty and elegance when they meditate on the equations that describe strings. They say without embarrassment that they believe this theory has merit exactly because of the beauty of the math. After all, Newton's beautiful equations described gravity, Maxwell's described electromagnetism, and Einstein's enlarged our understanding of these forces. They also gave us telecommunications and computers and landed us on the moon and set us off exploring our solar system. The fact is, there is no physical evidence for strings, and yet more and more young physicists devote their lives to finding some.
It seems to me that in some way which will be clearer as time passes, science and religion have again become one, as they were in the beginning. Humans have relentlessly quested after the one 'theory of everything' throughout all of our time here, and there is something amazing and fantastic in the idea that mathematics is perhaps the ultimate religious language, unifying all that is within one set of symbols. And the idea that these symbols describe a grand cosmic symphony, that all that is, is one? It seems the reconciliation of all our tumultuous history. Our tireless yearning to understand, to describe, to celebrate this existence of ours…maybe the universe expanded and expanded for 15 billion years just for this, for the day when one particular configuration of molecules and atoms and quarks and strings, which carries within it traces of all the rest, would be able to reflect on the magnificence of this creation, the universe reflecting upon itself. And find it good. Very good.