The String Theory

What do you know about The String Theory?

I've given a short description about it in simple language, so that it could be easily understood by everyone.

 In 1992, Theodore Kaluza gave a bizarre idea and proposed that our universe might actually have more than three dimensions, that is in addition to left-right, back-forth and up-down, Kaluza proposed that there might be additional dimensions of space that for some reason we don’t yet see. But this was just some explanation, we don’t know whether it’s right or wrong. This idea has had a major impact on physics in the last century.

Now I’d like to tell you about the stories of these extra dimensions. To begin, we need a little bit of back story, we go to 1907, when Einstein was working on a new theory to try to understand fully the grand pervasive force of gravity because even Newton had written that although he has understood how to calculate the effect of gravity but he was unable to figure out how it actually works! How is it that the Sun 93 million miles away somehow affects the motion of the earth? How does Sun reach out empty and inert space and exert influence.
So Einstein found that the medium that transmits gravity is space itself. He explained this through warps and curves of space. Imagine space as a flat blanket where there is no matter present. But if, there is some matter in the environment, such as the Sun which causes space of fabric to warp, to curve, and that communicates the force of gravity, even the Earth warps, curves the space around. Also the Moon is kept in orbit according to these ideas, which rolls around the valley, in the curved environment around the Earth. Likewise, Earth too moves around the Sun, or we can say, Earth is fall into the curved space of the Sun. This is the concept of Space-Time Fabrication. Refer the figure below.

 

 

Now that explanation of Einstein made Kaluza thinking. He like Einstein was, in search of a unified theory, which is one theory that might be able to describe all of nature’s forces from set of ideas and principles.

So influenced by Einstein’s idea, Kaluza explained electromagnetic force through warps and curves of space. That raises a question, warps and curves in what??
So Kaluza said, “Maybe there are more dimensions of space. To describe one or more force maybe I need one more dimension”. So while working on the three-dimensional equation which Einstein had already described, he found one more equation of fourth dimension which was equation of Electro-magnetic force.

Now two question arises: If there are extra dimensions, where are they? And does this theory really works when applied?

Answer to the first question: In 1926, a scientist said that there could be dimensions which are not easy to be perceived by us, but others might be curled up that we might not be able to see.

Answer to the second question: The scientists worked really hard on this, but in detail it detail it didn’t work. They didn’t find the mass of an electron work out correctly.

Now certainly by 50’s this strange but very compelling idea of how to unify the laws had gone away. But then by our age, by our era, a new approach to unify the laws of physics is being pursued by scientists such as Brian Greene, Stephen Hawking, etc., it is called the String Theory.
At beginning it has nothing to do with extra dimensions, but later it resurrects those ideas. The idea is based on, what are the basic, indivisible, uncuttable constituents present all around us? Imagine we’re looking at a candle, and we want to figure out what it is made of. So we go on a journey deep inside the object and examine the constituents. So going deep inside, we fall down to atoms, and we all know atoms are just not the end of the story, there we see little electrons swarm around the central nucleus, then we have neutrons and protons, even these aren’t the smallest particle, we zoom in further, we find quarks and that is where the conventional idea stops, and here is the new idea of string theory. Deep inside any of these particles (quarks) is something else, this something else is the dancing filament of energy which looks like a vibrating string and that’s where the idea of String Theory comes from. These vibrating strings vibrate in different patterns, they don’t produce different musical notes, rather they produce different particles making up the world around us. So the whole universe is ultimately built up of these tiny little filaments of vibrating energy, vibrating at different frequencies, the different frequencies produce different particles, the different particles are responsible for all the richness in the world around us. And there you see unification because matter particles, electrons and quarks, radiation particles; photons, gravitons, are all built up from one entity, so matter and the forces of nature all are put together under the roof of vibrating strings and that’s what we mean by the unified theory. But practically and mathematically, the string theory doesn’t work in the universe with just three-dimensions of space, it doesn’t work in the universe with 4-dimensions of space, nor five, nor six, finally you can study the equations and show that it works only in the universe that has ten dimensions of space and one dimension of time.

So this is all the basics of String theory you need to know about. And I'd like to thank the  theoretical physicist and string theorist Sir Brian Greene for introducing this wonderful concept to the world.

Happy reading friends. :)

*Sameep Baxi*