There was no such stagnation. This is the period which saw M-theory, the holographic principle, and the twistor revival,
I understand M theory sufficiently well to be seriously underwhelmed.
M theory and the holographic principle suspiciously resemble postmodernism: insiders talking to each other in ways that supposedly demonstrate their erudition, without any external check to verify that they are actually erudite, or even understand each other, or even understand what they themselves are saying. Twistors are valid and erudite mathematics, but don’t seem to get us any closer to anything interesting.
M theory is just string theory only more so. The trouble with string theory as a theory of spacetime is that it takes place in a fixed space time background, thus inherently makes no sense whatever. If you start with a contradiction, you can deduce anything you please. The central problem in any quantum theory of spacetime is that you have no fixed spacetime to stand upon, and string theory just blithely ignores the problem. That is not an advance in theoretical physics, that is finding weak excuses to publish meaningless papers.
The trouble with string theory as a theory of spacetime is that it takes place in a fixed space time background
That’s just an approximation. Those situations (flat space, hyperbolic space) are really just asymptotically fixed—the form of the space-time in the infinite past or the infinite future is fixed. But in between, you can have topology change.
String theory in positively curved space may even allow for topologically distinct asymptotic outcomes, but that is still a topic of great confusion.
There is a standard paradigm for applying string theory to the real world—grand unification, broken supersymmetry, compactification. I’d give that about a 50% chance of being correct. Then there are increasingly unfamiliar scenarios, the extreme of which would be a theory in which you don’t even have strings or branes, but in which some of the abstract properties of string theory (e.g. the algebraic structure of the amplitudes) still hold. The twistors could swing either way here: twistorial variables may exist for an orthodox string scenario, but there may also be twistorial theories way outside the usual M-theoretic synthesis.
That’s just an approximation. Those situations (flat space, hyperbolic space) are really just asymptotically fixed—the form of the space-time in the infinite past or the infinite future is fixed. But in between, you can have topology change.
I don’t think string theory as it exists is capable of of describing a space time that undergoes topological change as a result of the dynamics of the strings. They talk about branes undergoing topological change, but they undergo topological change within a given background spacetime that acts without being acted upon.
And if it is capable of describing such an event, string theorists don’t really have any idea of how to make it do it.
People go into Quantum Gravity because it is the big unsolved problem, find they cannot solve it, but they have to publish papers anyway. And so they do, resulting in postmodern physics.
There is a string counterpart to the old idea of “spacetime foam”, it’s called a “Calabi-Yau crystal”. The crystal fluctuates and branes are defects in the crystal. There are more things in string theory, sam0345, than are dreamt of in your philosophy.
That is just people waving their hands fast to distract you from noticing that not only do you have no idea what they are saying, they have no idea what they are saying either: Much like postmodernism, hence I described it as “postmodern physics”
Now you’re being paranoid. This isn’t a bluff, these aren’t just words. Compactification on a Calabi-Yau is one of the basic ideas for how to get realistic physics out of string theory, and “crystal melting” is a model of its microscopic quantum geometry.
Yes, and there are so many Calabi-Yau manifolds that just knowing that the world is a ten-dimensional spacetime with six dimensions rolled up into some Calabi-Yau manifold yields hardly any falsifiable prediction at all.
I understand M theory sufficiently well to be seriously underwhelmed.
M theory and the holographic principle suspiciously resemble postmodernism: insiders talking to each other in ways that supposedly demonstrate their erudition, without any external check to verify that they are actually erudite, or even understand each other, or even understand what they themselves are saying. Twistors are valid and erudite mathematics, but don’t seem to get us any closer to anything interesting.
M theory is just string theory only more so. The trouble with string theory as a theory of spacetime is that it takes place in a fixed space time background, thus inherently makes no sense whatever. If you start with a contradiction, you can deduce anything you please. The central problem in any quantum theory of spacetime is that you have no fixed spacetime to stand upon, and string theory just blithely ignores the problem. That is not an advance in theoretical physics, that is finding weak excuses to publish meaningless papers.
That’s just an approximation. Those situations (flat space, hyperbolic space) are really just asymptotically fixed—the form of the space-time in the infinite past or the infinite future is fixed. But in between, you can have topology change.
String theory in positively curved space may even allow for topologically distinct asymptotic outcomes, but that is still a topic of great confusion.
There is a standard paradigm for applying string theory to the real world—grand unification, broken supersymmetry, compactification. I’d give that about a 50% chance of being correct. Then there are increasingly unfamiliar scenarios, the extreme of which would be a theory in which you don’t even have strings or branes, but in which some of the abstract properties of string theory (e.g. the algebraic structure of the amplitudes) still hold. The twistors could swing either way here: twistorial variables may exist for an orthodox string scenario, but there may also be twistorial theories way outside the usual M-theoretic synthesis.
I don’t think string theory as it exists is capable of of describing a space time that undergoes topological change as a result of the dynamics of the strings. They talk about branes undergoing topological change, but they undergo topological change within a given background spacetime that acts without being acted upon.
And if it is capable of describing such an event, string theorists don’t really have any idea of how to make it do it.
People go into Quantum Gravity because it is the big unsolved problem, find they cannot solve it, but they have to publish papers anyway. And so they do, resulting in postmodern physics.
There is a string counterpart to the old idea of “spacetime foam”, it’s called a “Calabi-Yau crystal”. The crystal fluctuates and branes are defects in the crystal. There are more things in string theory, sam0345, than are dreamt of in your philosophy.
That is just people waving their hands fast to distract you from noticing that not only do you have no idea what they are saying, they have no idea what they are saying either: Much like postmodernism, hence I described it as “postmodern physics”
Now you’re being paranoid. This isn’t a bluff, these aren’t just words. Compactification on a Calabi-Yau is one of the basic ideas for how to get realistic physics out of string theory, and “crystal melting” is a model of its microscopic quantum geometry.
Yes, and there are so many Calabi-Yau manifolds that just knowing that the world is a ten-dimensional spacetime with six dimensions rolled up into some Calabi-Yau manifold yields hardly any falsifiable prediction at all.