= 27d567bc2d48d9f40e9ccc20ea370b15)
Mitchell_Porter comments on How about testing our ideas? - Less Wrong
You are viewing a comment permalink. View the original post to see all comments and the full post content.
= 783df68a0f980790206b9ea87794c5b6)
Loading…= b715d02e85f7b3b4ae65ca3d3e450868)
Subscribe to RSS Feed
Powered by Reddit
= f037147d6e6c911a85753b9abdedda8d)
You are viewing a comment permalink. View the original post to see all comments and the full post content.
Comments (113)
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.