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Gaffer Variety:
String Theory V054:
By Willie Gaffer:
August 21, 2006:
Recently I had the accidental pleasure of watching a super interesting show on PBS about string theory. It was accidental because I tuned into our local PBS channel out of desperation. It was a Saturday. I had been working outside all day, I was tired, and I just wanted to relax with a soda pop and something a little less mind numbing than golf. I was not hopeful. I was expecting to hit another rerun of an old Lawrence Welk show. I am ceaselessly amazed at how these PBS folks can pretend to such intellectual sophistication and then give us old LW reruns. This time, I was pleasantly surprised. This show was a lot less mind numbing that golf or LW. It was fascinating.
The show was a Nova presentation called "Elegant Universe." I missed the very first part, but I did discover who the commentator was. It was a physicist named Brian Greene. He was very good at making string theory understandable. Just to get us on the same page, this string theory is not about violins or any other kind of musical instrument. It is not about music at all. It is a relatively new theory about the structure, or lack thereof, of our universe.
Another wonderful thing that happened is the second segment of that same show was aired a few days later on PBS. I tuned in thinking it would be a rerun of what I had seen and I would be able to catch what I had missed, To my surprised and delight, it was a continuation. Greene, by the way, has also written a book with the same title. It is offered by B&N for 20 bucks in hardcover. It might be worth the price and your time.
Well, what about string theory? Up until recently the field of subatomic science has been dominated by a theory of energy and matter called quantum mechanics or quantum theory. This is really a branch of mathematical physics that deals with the nature of energy and matter. In particular, it is concerned with how energy is emitted and absorbed and in how particles behave. In this theoretical model energy and matter exist in tiny discrete amounts called quantum (singular) or quanta (plural). Hence the name quantum mechanics. It is particularly suited to the study of elementary particles and the interactions between them.
For sure, there are even older models of the universe which we call classical physics. In that world we return to the theories and mathematics of Newton and Euclid. This is the good old temporal world with which all of us are familiar. It's the world we see and is impossible to refute. In our familiar Newton Euclid world, energy is treated as a continuous phenomenon and matter is assumed to occupy a very specific region of space and to move in a continuous manner. That's fine for the world of automobiles and bicycles. The shortest distance between two point is a straight line and gravity will get you if you slip and fall. These familiar rules break down, however, in the world of subatomic physics.
This is where quantum theory takes over. According to quantum theory, energy is emitted and absorbed in small packets, called quanta which in some situations behaves as particles of matter. In addition particles sometimes act like waves wherein they cannot be viewed as localized in a given region. They seem to be in many places at the same time. So quantum theory sees a dual nature for both waves and particles, with one behavior active in some situations and the other active in other situations.
Quantum mechanics is effective in explaining many properties of matter, but not all. Physicists define four fundamental forces in our universe and quantum mechanics explains only three of them. Without going into spiraling detail the forces are the strong interaction, the weak interaction, electromagnatism, and gravity. We all pretend to know about electromagnatism and gravity. The strong and weak interactions have to do with how the small elemental particles are held together and how they interact. Quantum mechanics can give mathematical descriptions of the strong and weak interactions and electromagnatism. It fails in providing a mathematical model for gravity.
To complete the picture we need Dr. Einstein's theory of relativity. Relativity is necessary to explain the attraction between bodies that we call gravity. These two theories, quantum mechanics and relativity, have been the basis for modern physics. While quantum theory deals with the world of the very tiny particles, relativity theory deals with the world of large bodies like planets and their interactions.
The problem with all of this is there is no unifying theory which explains everything in a neat package. The thinking goes, if these theories are completely valid, there should be a way of unifying them mathematically. Dr. Einstein spent most of the remainder of his life attempting to solve the conundrum. He searched for what he called a unified field theory. So far, that magic has evaded the scientific community.
This is where string theory comes in. This is also where it gets pretty weird. String theory is a model of the universe which postulates that particles are really one-dimensional extended energy strings rather than the zero-dimensional points that are the basis of the quantum mechanics model. Got that? Me neither! Let's think of it as kind of a game. I think that's what these physicists do.
Anyhow, the idea of string theory is, the universe consists of nothing more that tiny strings of energy. Maybe they are closed strings (like a rubber band) and maybe not. Either way, these things have unique vibrational characteristics which cause them to appear as different types of subatomic elements or particles. When we say tiny we mean lengths of about the negative 35th power of ten. As I said, these things vibrate or resonate at specific frequencies causing them to appear as different particles. They can also split and combine. Thus they would emit or absorb other particles. Sure!
Now here is the really weird part. There are at least five versions of string theory that appear to be equally valid. Really! Not only that, but depending on which flavor of string theory you choose, these theories demand degrees of freedom in more than four dimensions. Ho boy! So, we have our three normal dimensions of Euclidian Geometry plus time as another dimension, per Einstein. Now string theory tells us there must be six more dimensions to accommodate these new theories giving us a total of ten. Also, there are, we are told, other objects which exist in these extra dimensions. Ho boy again.
Now, why would we put up with such nonsense? The reason is, these string theories, any one of them, provides a mathematical model which accounts for all four of our fundamental forces. String theory is seen as a theory of everything. Another point is, we have not proven string theory to be wrong. It has not made a statement that can be experimentally tested and proven false. To be sure, our scientific community is working on that. In the meantime work goes on in trying to understand all of the ramifications of this newest theory, or set of theories.
This set of theories has been the real stumbling block for many scientists. They might ask, will the real string theory please stand up. If the theory is valid, our common sense must demand that there be only one of them, not five. Well, it turns out a fellow named Ed Witten seems to have resolved the conundrum. He explained and proved to the scientific community his own theory that the five theories were simply the result of different perspectives. From a higher perspective, so to speak, the five merge into one and this demands yet another dimension. The ten dimensions become eleven. Not only do we have all those other dimensions, these guys also speculate that there are parallel universes and worm holes out there. Shades of Star Trek. This is stranger than science fiction.
This new theory is called M theory. No one seems to know why, but that's what it's called. I suspect we can guess string theory and M theory will not be the last words in physics. It is, however, a step along a long and fascinating journey for mankind. That it is not the last word is fortuitous for physicists. It would be a tragedy of the first order for a person to spend half of his or her life to become a physicist only to discover there was nothing more to do.
For more comprehensive information on string theory, go to
"Ask Jeeves" on the web and type in the phrase "String
Theory" for your search. You will be amazed. There is a link
to "Ask Jeeves" on my links page "Portals, Directories,
and ISPs." You might also want to purchase Greene's book.
It's also available in paperback for the economy minded like me.
Amazon offers it for $10.37.
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