Richard Pearson FRAS
[Tomorrow 5 July I take a look at The Arrow of Time]
Everything around us seems solid and genuine; the brick walls of buildings and infrastructure of roads, railways, airports and space-ports. The structures of all modes transport, and spaceships. Along with the biological make up of all life here on earth, and the various life forms in the Universe as a whole. If we punch a wall or a wooden desk, it really does hurt. People are killed and injured in motor car accidents, train crashes and so forth. To us the world is without doubt ‘real’, and the Universe does contain a great deal of amazing stars, extra-solar-planets, gas clouds, along with exotic objects like black holes, all of which are physical bodies. Astronomers have been studying the Universe with telescopes since the time of Galileo Galilei in 1609, and have managed to explain the physical phenomena of what they have revealed, while new discoveries are made all the time.
“Yet atoms contain a great deal of empty space, so much so that it does not seem plausible that solid objects exist in real terms. In String theory atomic particles like photons, neutrons and electrons can exist either as tiny vibrating strings or fuzzy blobs of atomic particles. So, our world and the Universe should not contain any solid objects at all, yet as intelligent human beings, we know that it does.”
We live in a wonderful complex universe, and we are curious about it by nature. So, what is the world made of? Ordinary matter is made of atoms, which are in turn is made of just three basic components: electrons whirling around a nucleus composed of neutrons and protons. The electron is a truly fundamental particle, but neutrons and protons are made of smaller particles, known as quarks. Quarks are, as far as we know, are truly elementary.
Our current knowledge about the subatomic composition of the universe is summarized in what is known as the Standard Model of particle physics. It describes both the fundamental building blocks out of which the world is made, and the forces through which these blocks interact.
The behaviour of all of these particles (and forces) is described with faultless precision by the Standard Model, with one notable exception: gravity. For technical reasons, the gravitational force, the most familiar in our everyday lives, has proven very difficult to describe microscopically. This has been for many years one of the most important problems in theoretical physics, to formulate a quantum theory of gravity.
In the last few decades, string theory has emerged as the most promising candidate for a microscopic theory of gravity. And it is infinitely more ambitious than that: it attempts to provide a complete, unified, and consistent description of the fundamental structure of our universe. (For this reason, it is sometimes, quite arrogantly, called a 'Theory of everything').
Today String Theory has been superseded by M-Theory, M for membrane. The essential idea behind string theory is that all of the different 'fundamental' particles of the Standard Model are really just different manifestations of one basic object: a string. How can that be? Well, we would ordinarily picture an electron, for instance, as a point with no internal structure. A point cannot do anything but move. However, if string theory is correct, then under an extremely powerful 'microscope' we would realize that the electron is not really a point, but a tiny loop of string. A string can do something aside from moving. It can oscillate in different ways. If it oscillates a certain way, then from a distance you would be unable to tell if it is really a string, we see an electron. But if it oscillates some other way, then we call it a photon, or a quark. So, if string theory is correct, the entire world is made of strings!
Perhaps the most remarkable thing about string theory is that such a simple idea works. It is possible to derive an extension of the Standard Model which has been verified experimentally with incredible precision from a theory of strings. But it should also be said that, to date, there is no direct experimental evidence that string theory itself is the correct description of Nature. This is mostly due to the fact that string theory is still under development. We know bits and pieces of it, however we do not yet see the whole picture, and we are therefore unable to make definite predictions. In recent years many exciting developments have taken place, radically improving our understanding of what the theory is. Therefore, String Theory informs us that there is only one true unique atomic particle that can change into other particles in the Standard Model, depending upon the vibration of its component string.
Physicist Albert Einstein (1879 -1955) introduced us to General Relativity in 1916. He said that the speed of light (299,792,458 metres per second) is a constant; nothing can travel faster than the speed of light. Therefore, a star ship that has been accelerating every year for five years to reach 95% of light speed, constantly has to use extra energy to allow it to move faster, because the Mass (of the spaceship) increases to infinity at light speed. Therefore, if the hull of our star ship is made up of iron atoms, as the star ship approaches the speed of light, these iron atoms must also increase in Mass. If this is the case, then how does this allow them to sit happily in the periodic table? I believe that String Theory offers the best answer: the vibrating string that makes the atomic particle ‘iron,’ would vibrate slower as time itself slows down. Does this turn the iron-atom into another type of particle? It is more likely that the particles that make up the iron atom act in a relative way just as Time does, in relation to other nearby atomic particles that are not in the hull of the spaceship.
However, since no spacecraft has reached light speed, we are unable to test this suggestion for the foreseeable future.
In the Universe, there is an increasing collection of exotic objects like black holes that amplify the Mass of ‘approaching’ atomic particles, so much so that the laws of physics of what we know about the Standard Model, could break down in areas around such mysterious objects. Like other physicists I also suggest that the laws of physics are not the same everywhere in the Universe. It is unsafe to assume that the laws of physics are the same everywhere.
“Everyday objects we take for granted in our daily lives, are not, as far as we know, subjected to the same great forces at play we see in the Universe, as a result the building blocks of matter that compose our world is in a steady state, which is beneficial to the origin of life as we know it. Yet it is still puzzling as to why all the solid things we take for granted, that desk, the chair or the brick wall at the far end of your office, is really an illusion.”