I have been reading about M-Theory and LQG, and from what I read they are actually very similar.(adsbygoogle = window.adsbygoogle || []).push({});

It seems that just a a string-world sheet is the same as a sum of an infinite number of Feynman diagrams, a membrane would be the sum of an infinite number of graphs or networks. Or as Susskind suggested, 0-branes connected by strings. Which if you draw it looks a lot like a network of points and lines.

In M-Theory there are not separate membranes (since any two can be connected by an infinitely thing tube of zero energy) just one big one. And presumably the lowest energy state where the membrane has lowest surface area it would simply collapse to a network of thin tubes like a network. The only thing that would differentiate this infinitely thin tube from nothing at all would be the charge or spin it carried.

Some people suggest that we live 'on' that membrane. So that the Universe 'is' this membrane.

On the other hand LQG suggests that space-time can be described by spin networks. That the Universe 'is' this network.

So two theories both described in terms of an infinite sum of networks. Albeit in string theory the network might be more "stringy" and in 10 dimensions and have supersymmetry.

I don't know how particles arise in LQG, but equally I'm not entirely sure how strings arise in M-Theory, presumably as charged loops in the membrane which preserve charge and spin.

So really when everyone says these are completely different theories I am confused because they seem remarkably similar. What do you think?

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# In what way is M-Theory different from Loop Quantum Gravity?

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