What exactly is the M- Theory?

Question

Is it a complete theory yet? Or just a conceptual idea of uniting all the branches of string theory with supergravity ect..
Does M- theory claim that the universe started as a collision of 2 d- branes? If so, where did the branes come from in the first place? What gave them movement?

Answer 1

No, M Theory is not yet a complete theory, and no one, not even its inventor, knows exactly what it is. M Theory is merely a proposal of how ALL the various different "strands" of Superstring Theories are "tied" together (mathematically via some transformation), and that they are essentially the same theory, but presented differently. This highlights the duality that exists for all manifestation of reality (the most basic example being the particle-wave duality).

M Theory does introduce some new concepts such as an additional dimension that allows the existence of "branes", which are multi-dimensional versions of the "string". The extra dimension also ties it mathematically to Supergravity, demonstrating that M Theory and Supergravity are essentially different variations of the same theory.

Also, M Theory proposes (not claim) that the Big Bang which created the Universe could be the result of a collision of 2 d-branes, but this is pure conjecture. There are NO evidence that this is true, since we haven't even yet proven the existence of strings, nor branes. The question of where the d-branes comes from is essentially the same question as "where did the Universe come from?" We don't knoew yet.

BTW, just as a side note, the reason that M Theory and all Superstring Theories are NOT complete theories is because we lack a fundamental framework for expressing the equations of motion of these theories. It's basically like when the ancient Greeks observed that objects thrown into the air eventually falls back to the ground, so they devise a theory that says all objects falls to the ground, but the heavier the object the quicker they fall back, and the lighter the object, the longer they stay afloat. Obviously, this is wrong because they lacked the fundamental principle of gravitational force, and they lacked the mathematical tools to write down the equations of motion that can describe exactly how objects behave within a gravitational potential well. In the same way, we lacked the mathematical tools to write the equation of motion for String Theory, and we don't have a fundamental principle to describe the theory coherently.

Answer 2

No. No. No. Unknown. Unknown.

Start with a book written for a general audience, like the reference. The book, not the PBS show.

While some have hypothesized that our universe formed as the intersection of M-branes, that's not a key part of any string/brane theory. The entire field is a long, long way away from having a complete theory. And none address the issue of ultimate cause or origin.

Answer 3

Its just math that fits many observations of the universe.

Answer 4

very confusing point. research over google. that will can help!