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You may wonder what M-theory means. For the average person who only has a basic understanding of physics the idea of M-theory would be pretty difficult to grasp. In this article we will try to present in way that is more accessible. First off the main goal of physics is to understand the various motions that guide the universe and its interactions. Modern physics has managed to explain three of the four main interactions but has not found a proper explanation for gravity. Whenever values for gravity are applied to the standard model, the values are too large to be practical.
The M-theory is the culmination of an alternative concept to the standard model. The standard model bases the interactions of the physical world on particles. These basic particles are considered to be the fundamental building blocks of the universe. However, as mentioned gravity does not seem to fit in standard model of physics. The reason is that gravity is described in two different ways. The first is special relativity a concept developed by Einstein. According to Einstein’s theory of special relativity gravity is a curve in space time caused by massive object. In quantum theory gravity is described as the result of a theoretical particle, the graviton.
To address this inconsistency string theory emerged as a viable alternative. Instead of particles, strings are the basic unit of all matter. They can be either open or closed and vibrate at different frequencies. These different string frequencies create the fundamental particles as we understand them. String theory goes further by stating that the universe has 10 dimensions rather than 4. The 4 we know of directly are the three dimensions of space and one of time. However string theory states that there are 6 more dimensions tightly curled up in the others that are not visible. These extra dimensions are considered as derivations of the main 4.
So if string theory is so comprehensive why is it still considered incomplete. The main problem is that there are five viable string theories. Three of them deal with superstrings and two deal with heteorotic strings. Each theory has strong foundations and the equal difficulty of finding practical ways of testing them.
M-theory was developed as a solution as means of testing these theories arose. In essence it states that the reason why each of these five string theories are valid is that each are a different aspect of the same theory. Another interesting assumption is that instead of just 10 dimensions there are actually 11. If proper means of testing M-theory could be found it could become a definitive unified field theory.
We’ve also recorded an episode of Astronomy Cast all about String Theory. Listen here, Episode 31: String Theory, Time Travel, White Holes, Warp Speed, Multiple Dimensions and Before the Big Bang.