|There was a wonderful TV program of NHK entitled "The Elegant Universe, Unification Theory" on two weeks ago. It was so instructive program for me. After watching this, I felt as if all of my doubt on the recent development of the theory of universe had gone away.
I have been a watcher of the Universe Theory for the last 40 years. When I was the 3rd grade boy of the elementary school, I learned that Dr. George Gamow explained that the beginning of the universe was a fire ball. Since then it had been a fan of the scientists who study the origin of the universe. However I could not imagine that such a short period of only a half century the progress of the study of universe has developed so much.
Of course I can't understand the complicated formula of mathematics. So what I had learned was reading the book of famous scientists or watching TV on universe. Through having doing like this way, I thought as if I could know the recent studies on universe. I know that Dr. Sato is one of Tokyo University who created the theory of Big Ban, or Dr. Stephen William Hawking is now studying the black hole etc. I have been a good reader of the scientific magazine of "Newton", which sometimes takes the universe as their topics.
However, for the last few years I could not understand a new theory on universe, which was taken by the science magazine Newton. It is titled as "String theory". It seemed to be successful to explain the unified force theory of space. There are four kinds of forces; these are gravity, electromagnetism power, a weak nuclear force and a strong nuclear force. Dr. Weinberg and Dr.Saram were awarded of the Novel Prize for creating this Grand Unification Theory, which can unify three powers, electromagnetism power, a weak nuclear force and a strong nuclear force. But they failed to unify gravity with other three powers. "String theory" has come out newly and seems to be successful to unify all of these powers. It states as below;
The fundamental factor of our world is a vibrating string. Our world is floating on a multi-dimensional brain. Our universe is only one of them. When I read the magazine Newton, there were some pictures to explain the String theory. However I am afraid that the author seemed not to understand this theory, his writing was insufficient to make readers understand. There were some pictures floating bubbles in space or several rubber rings. So I was frustrated to read them. I had very bad impression on it.
However the TV program made in this United States was the complete answer to my doubt exactly. It made the amateur scientist like me understand what kind of theory it was. I recorded this program into two DVD disks; I will watch it any time. What would happen if I would watch this program after 25 years later? It would be either I will be surprised what an antique theory it is or I will be impressed that this is the beginning of a great theory.
Well, I will review of what programs they were. First of all, the navigator that appears on the screen and explains the history of the theory concisely was a young man at the Columbia University, named Brian Green. He was quite a handsome young man. He entered the Columbia University and measured in the String theory.
The String theory is the world like the science fiction novel. It explains that this world consists of the space of 11 dimensions. The component of space is vibrating small energy that is called a string. A string vibrates by various patterns, which make it either various materials or energy by the vibration pattern.
It would be very elegant and wonderful if we could get such a theory that can explain various phenomena of space. The purpose of physics was exactly like this. For example, Isaac Newton proved that both of the phenomena that an apple drops down on the ground and the phenomena that the moon goes around earth are the same power of the universal gravitation. This is the first attempt and a really wonderful achievement to explain the gravity scientifically. It is an elegant theory. However only one problem of his theory is that he can't explain why and how the gravity is born.
Dr. Albert Einstein was born in the end of the 19th century. When he was 26 years old, he did a surprising discovery that there was no such substance, whose speed exceeded the speed of light. However it was found that this fact contradicted Newton's theory of universal gravitation, to tell the truth. For instance, it is assumed that the sun disappeared suddenly. Then, the planet goes out of orbit at once and will dash out to space in according to the theory of universal gravitation. However, Einstein knew that light did not reach to the earth at once. Actually, the light of the sun reaches to the earth after eight minutes. Therefore, he thought that before the arrival of the light the earth should not come off from the revolution orbit to which the earth turns round the sun. The reason is because the speed of the gravity is the same as the speed of light. Starting this idea, he studied for about 10 years. Finally Einstein reached to a unique idea that the universe was just like as the cloth of the 4th dimension composed of the 3 dimension Space and 1 dimension Time. When the sun would disappear, this 4 dimension cloth must be distorted at that time. The wave of gravity reaches to the earth at the same speed as light, then the earth came off from the revolution orbit. Einstein explained that the gravity was a distortion in a space and time's cloth. This is the theory of General Relativity. So far the correctness has been proven by observing the space.
Next, Dr. James Clerk Maxwell found four equations, which can prove the unity of the electricity and the magnetism. This attempt was successful and these two powers were united newly as the electromagnetism power. So Einstein tried to unite gravity and this newly found electromagnetism power. However the gravity is relatively very weak force mysteriously compared with the electromagnetism power. He could not do it so well easily.
Dr. Niles Bohr designed a new outlook on the universe in 1920's. The atom consists of smaller elementary particles. It was impossible for the conventional theories of Einstein and Maxwell to explain the phenomenon that had happened in these elementary particles. Bohr discovered a new theory that the extremely small world of the quantum such as atoms and elementary particles is the world of the probability. Bohr said that there was no certain thing in the world quantum. This seemingly strange theory perfectly matches with the experiment results. Therefore gradually many scientists have supported this theory of Quantum. However Einstein could not agree with this idea He had a strong belief that there must not be uncertain one in this world. So he died with leaving the difficult question how to integrate gravity and the electromagnetism power.
Because electromagnetism power, strong power (power to unite the proton with the neutron) and weak power (power that rules radioactive decay) have already been integrated in modern physics, how we should integrate these powers and gravity should be remained as the most difficult problem. The scholar who researches this problem has been divided into two groups. One is the group that researches the world of a very small scale, such as atom and elementary particle by using Bohr's Quantum Mechanics theory. Another is the group that researches the big world, such as the stars and galaxies by using Einstein's General Relativity theory. These two groups have been developed separately. However they have reached to special phenomena, which could not be found without these two theories at the same time. This is so-called black holes. It was Shubaltsshult, who predicted the existence of black holes. But his study has been thought that it was only the matter of theory, not the real phenomena. However some black holes were actually discovered, that forced us which of these two theories we should make use. In nature, both of galaxies and elementary particles are the part of our world. We should and could explain both of them by using only one theory.
In nature, a black hole has been made as following. A big and heavy star collapsed and reached such stage as it can't sustain its shape. The star started shrinking in one point. And the black hole will become larger by eating surrounding substances. According to the standard big bang theory, when we go back toward the starting point of the universe from the present time, it will become higher density, smaller and hotter. Finally it will reach to the only one point finally at last. And at this point, both of the two theories of General Relativity and the Quantum Mechanics would fail respectively.
It is expected that "String theory" will be able to solve this issue. "String" is thought to be the vibrating existence of extremely small. Since its beginning, this theory has passed various twisted ways. The first scientist who thought of this theory was an Italian scientist Dr. Gabriele Veneziano. Through his study, he happened to read the book of mathematician Leon Halt Euler in Switzerland by chance. And he found that his formula can explain the strong power out of four powers. This is the beginning of the String theory. Physicist Dr. Leonard Suskind in the United States shut himself up in the attic and researched this intensively. He found that this formula implied the existence of a particle. The shape is the one that the rubber band or rubber band cut in the half. He was so happy to this discovery and wrote the document and sent it to a science magazine. However his writing was neglected without paying attention at all. As he was so desperate that he just drunk, which was a famous anecdote.
In the course of the study of the big bang, Dr. John Shuwalts and Dr. Michael Green discovered an elementary particle that conveyed the gravity. It was named as the graviton. Both of them studied together. The top priority of their study on the String theory was how to solve the mathematical contradiction of anomaly that existed in the String theory. One stormy night, they divided into one side and the other side of the blackboard. They started the calculation separately. They reached to the quite the same answer at the end. It was proven that mathematical contradiction that existed inside the string theory was perfectly solved.
The String theory is now called as the theory of every thing. The atom is made of the elementary particles and the elementary particle consists of Quark. The String vibrates in each peculiar pattern. This vibration patterns shows the difference of four powers. The String theory is very elegant theory to be able to explain both of gig and small sized worlds. However the weak point of this theory is that we can't prove it through the experiment or observation. It is said that such theory on which we can't experiment or observe is not the science idea, but the philosophy. In addition to this, the String theory invites another doubt, because it needs a higher dimension universe, which exceeds four dimensions. So far no one believes that there is more than five dimension world. The String theory states that the string is very small existence, where the other dimensions except four dimensions have been rolled up. As a result there are such world more than four dimensions. However we can't prove such extra dimensions.
By the way, there are Primary Constants only of 20 in our universe, such as the mass of electrons and electromagnetism power. However if we would change one of these Primary Constants, the universe would be drastically changed and seems to be difficult to keep the present style and shape. For instance, we would simulate what would happen if we make the constant of the electromagnetism power just by a little. We would easily know that there is no more our space, because the stars can't burn by themselves and whole universe would keep in black and dead. It means that our universe of today could not exist. The String theory says that the shape of the dimensions rolled up will decide the primary constants.
The String theory is just like as the world of science fiction. We are on a brane of four dimensions that floats on the universe of higher dimensions. There is parallel universe next to ours. The one that had been thought the particle up to now and had researched is a string that vibrates in each pattern. The string vibrates by various patterns, makes the particle and makes our universe. If only we would study the character of the string, it is possible for us to explain from the elementary particle to the grand galaxy indeed elegantly. Exactly, the String theory has the possibility of becoming the unified force theory of universe.
In the string theory, there was another big problem besides mathematical contradiction, anomaly. After the research of various scientists, it diversified into five versions. This was too many as the unified force theory. It was Dr. Edward Witten who nicely solved this difficult problem. Most of the String researchers all over the world gathered in the Southern California University in 1995. Dr. Witten announced a new idea to solve this problem. What he did was to add another one dimension to the String theory. So far the number of dimension of the String theory was 10. As he added one more, so the total number of dimensions of the String theory has become 11. He proved that 5 versions observe the same phenomena by different angles. His new idea was named as "M" theory and hurly-burly happened. All of the theoretical problems of the String theory came to be solved by his contribution.
The scientists noticed the existence of the brane in 11 dimensions. There can be such a big sized brane as universe. Moreover the entire universe exists on one brane, which exists in a lot of dimensions. It is just like as bread. When we slice the bread, we can find various universes. Our universe is one of these parallel universes. As long as human being body exists is in the brane of 4 dimensions, it is natural why we can't touch or feel other parallel universes.
By the way, gravity is the power to keep our solar system in the Milky Way and makes human beings stay on the earth. Looking these facts, we think that gravity is a great power. However, actually gravity is very weak power to compare with other three powers. For instance, the electromagnetism power is far stronger than gravity. The string theory explains why the reason is so. We cannot feel the strength of gravity for some reasons, although gravity is strong power in reality. For example, gravity is to diffuse like the sound wave that occurs when the gem knocks against by a billiard stand. In a word, the gravity that arose in our world diffuses to other parallel universes. Why only gravity is so is that everything related to the shape of "String". M theory implies that the both ends of the string that makes the material or energy are kept on the 4 dimension universe. Therefore, it is possible to move only on the brane. However, the graviton, which creates gravity, is the String on one circle, which is not kept on our 4 dimension universe. So it is easily going out from our universe to the other parallel universes. That's why we can see the gravity is not so
Then, what kind of relation it is between our universe and the parallel universes? String theory has an answer to this question. Before that I would like to show the weak points of the standard theory of the big bang. If we would trace the time to the point of big bang, at a certain point, all physical theories could not be effective. How we should solve this? This is the first problem. Also the big bang theory can't explain why the big bang happened. This is the second question.
A researcher of the String theory announced that the universe had existed since the eternal past. If the String theory is correct, the big bang is related to the brane that float on higher dimension universe. The big bang occurred when two brane collided to each other by some reasons. These collisions have been repeated in the limitless world since the infinite past. However, at this moment, we can't understand under what condition or why the collision would occur.
In research laboratories of the United States and Europe, the experiment that examines the evidence of the String is conducted by using a huge accelerator. The purpose of this experiment is to discover the super symmetric partner that the existence is prophesied by the String theory. Of course, it is not always the direct evidence of the String theory. However it will be a powerful circumstantial evidence of the String theory. Hydrogen is thrown into the accelerator. After putting a high voltage of electricity, electrons are stripped off. The atomic nucleus of hydrogen will be accelerated up to nearly the speed of light and to collide to each other in the accelerator. If graviton would be generated, it should run away to another dimension. If the String theory is correct, it should be observed. Fermi National Accelerator Laboratory of the United States and the CERN of Europe are competing.
Thus, there are pros and cons on the String theory among researchers and scientists. The people who oppose to the theory claims that it is not the science but the philosophy, because we can't prove its correctness. On the other hand, the people who agree with the theory say that this theory is very elegant and attractive one among many other theories on universe. They add that some other day someone should prove that the String theory right. Certainly, this is the matter of a philosophy or a religion, rather than science. But it is interesting indeed.
(March 24, 2005)
Views from the Hubble Space Telescope
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