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I am aware of that. Which is why I tried being very precise with my words: > However, AdS/CFT hasn't produced a single bit of verifiable experimental evidence

I am aware of that. Which is why I tried being very precise with my words: > However, AdS/CFT hasn't produced a single bit of verifiable experimental evidence in the realm of black holes

whatshisface 6y ago
Given that there have been exactly zero experiments conducted in laboratories close to black holes, isn't that qualifier kind of a cop-out? Our entire observational knowledge of black holes consists of radiation emitted from the accretion disk (deep in the classical regime), orbits of nearby objects (even farther in the classical regime), and one blurry radio picture (predicted by GR and containing nothing, yet, to our knowledge, outside of GR's predictions.) I guess you could count gravitational waves, but guess what, that's GR too... ;) Given the observational knowledge of today, even a true theory of quantum gravity beamed back from the future would fail to produce verifiable experimental evidence in the realm of black holes.
- codethief 6y ago
  > Given that there have been exactly zero experiments conducted in laboratories close to black holes, isn't that qualifier kind of a cop-out? No, I don't think it is. I agree of course that it's hard to test predictions regarding black holes. But I was addressing OP's statement that > For example, you can use string theory to study the structure and behavior of black holes and holography, something called AdS/CFT, an area that has been incredibly successful. and I merely intended to express my disagreement with the claim that AdS/CFT has been "incredibly successful". Successful in what way? Measured by what metric? Clearly not by the usual metric that says that experimental evidence is what counts. And on top of all of that AdS isn't even close to the spacetime describing the known universe. > Given the observational knowledge of today, even a true theory of quantum gravity beamed back from the future would fail to produce verifiable experimental evidence in the realm of black holes. I don't think this is necessarily true. See, for instance, https://backreaction.blogspot.com/2020/01/how-to-test-quantum-gravity.html https://backreaction.blogspot.com/2020/01/how-to-test-quantu...

I am aware of that. Which is why I tried being very precise with my words: > However, AdS/CFT hasn't produced a single bit of verifiable experimental evidence in the realm of black holes

whatshisface 6y ago

Given that there have been exactly zero experiments conducted in laboratories close to black holes, isn't that qualifier kind of a cop-out? Our entire observational knowledge of black holes consists of radiation emitted from the accretion disk (deep in the classical regime), orbits of nearby objects (even farther in the classical regime), and one blurry radio picture (predicted by GR and containing nothing, yet, to our knowledge, outside of GR's predictions.) I guess you could count gravitational waves, but guess what, that's GR too... ;) Given the observational knowledge of today, even a true theory of quantum gravity beamed back from the future would fail to produce verifiable experimental evidence in the realm of black holes.

codethief 6y ago
> Given that there have been exactly zero experiments conducted in laboratories close to black holes, isn't that qualifier kind of a cop-out? No, I don't think it is. I agree of course that it's hard to test predictions regarding black holes. But I was addressing OP's statement that > For example, you can use string theory to study the structure and behavior of black holes and holography, something called AdS/CFT, an area that has been incredibly successful. and I merely intended to express my disagreement with the claim that AdS/CFT has been "incredibly successful". Successful in what way? Measured by what metric? Clearly not by the usual metric that says that experimental evidence is what counts. And on top of all of that AdS isn't even close to the spacetime describing the known universe. > Given the observational knowledge of today, even a true theory of quantum gravity beamed back from the future would fail to produce verifiable experimental evidence in the realm of black holes. I don't think this is necessarily true. See, for instance, https://backreaction.blogspot.com/2020/01/how-to-test-quantum-gravity.html https://backreaction.blogspot.com/2020/01/how-to-test-quantu...