You don't need a full fledged theory of quantum gravity to describe Hawking radiation. Quantization of the gravitational field isn't relevant for that phenomenon. Similarly you don't need quantum gravity to describe large elements. Special relativity is already integrated into quantum field theory.

In some ways saying that we don't have a theory of quantum gravity is overblown. It is perfectly possible to quantize gravity in QFT the same way we quantize the electromagnetic field. This approach is applicable in almost all circumstances. But unlike in the case of QED, the equations blow up at high energies which implies that the theory breaks down in that regime. But the only places we know of where the energies are high enough that the quantization of the gravitational field would be relevant would be near the singularity of a black hole or right at the beginning of the Big Bang.

re 2: special relativity is not general relativity - large elements will not provide testable predictions for a theory of everything that combines general relativity and quantum mechanics.

re: "GR environments (such as geostationary satellites)" - a geostationary orbit (or any orbit) is not an environment to test the interaction of GR and QM - it is a place to test GR on its own, as geostationary satellites have done. In order to test a theory of everything, the gravity needs to be strong enough to not be negligible in comparison to quantum effects, i.e. black holes, neutron stars etc. your example (1) is therefore a much better answer than (2)

Can't black holes explain Dark Energy? Supposedly there was an experiment showing Black Holes are growing faster than expected. If this is because they are tied to the expansion of the universe (univ. expands -> mass grows), and that tie goes both ways (mass grows -> universe expands), boom, dark energy. I also think that inside the black holes they have their own universes which are expanding (and that we're probably inside one too). If this expansion exerts a pressure on the event horizon which transfers out, it still lines up.

What's the "quantum measurement problem"? And why is it a problem? I get the wave function collapses when you measure bit. But which part of this do you want to resolve in a testable way?

Getting into the weeds about what is and is not "A Theory" is an armchair scientist activity, it's not a useful exercise. Nobody in the business of doing physics cares or grants "theory status" to a set of models or ideas.

Some physicists have been trying to build an updated model of the universe based on mathematical objects that can be described as little vibrating strings. They've not been successful in closing the loop and constructing a model that actually describes reality accurately, but they've done a lot of work that wasn't necessarily all to waste.

It's probably either just the wrong abstraction or missing some fundamental changes that would make it accurate.

It would also be tremendously helpful if we had some new physics where there was a significant difference between an experiment and either GR or the standard model. Unfortunately the standard model keeps being proven right.

I don't think that's quite the problem. In mathematics, the word "theory" is often used when referring to particular mathematical frameworks (e.g. Group Theory, Graph Theory, Morse Theory). In that sense I think String Theory is very much a theory. As you imply, in physics, the word "theory" is typically used in a different sense. I'm not a physicist but I presume a physical theory has to be verifiable, consistent with observations, able to predict the behavior of unexplained phenomena. If I understand correctly, the basic problem is that in some quarters string theory is being passed off as a physical theory. I know of pure mathematicians who are interested in string theory and who couldn't care less whether its a physical theory.

I remember a video talk by Witten where he said string theory predicts the existence of gravity, and nothing else does.

Wellllll. Despite the title, the paper does not make a claim about string theory. The starting point is the "Witten string field theory" which is a field theory engineered to have properties like string theory. Nothing guarantees that theory is exactly like string theory. In addition, the idea is perturbative in nature, there's no guarantee that perturbative effects are in fact realized in the full quantum theory - exoteric cancellations happen often in field theories with many symmetries. This is two degrees of questionable.

So A) the paper isn't actually about string theory and B) it's not clear that the claim it makes is actually correct for the field theory it supposedly applies to.

> That’s just piggybacking on a prediction of special relativity itself.

Let me stop you right now to inform you you don't understand how scientific theories are structured. Special relativity is not a prediction of special relativity. Likewise, 1+1=2 isn't a predict of arithmetic, it's the starting point.

No. Special relativity postulates that special relativity is preserved at all scales. It's an axiom. Comes from nowhere. It's assumed.

This is what a theory is: assume XYZ is true, and see how much of the world you can explain. Why is XYZ? That theory doesn't explain it.

Theoretical physics is: what is the smallest set of XYZ assumptions that can explain other theories. So if you can come up with a theory that's internally self-consistent that _predicts_ something which is postulated by another successful theory, that's a very convincing result.

It does, but a number of alternative theories of quantum gravity do not. So, if Lorentz invariance is shown to be violated, this would favor those over string theory.

Because String Theory hasn't delivered falsifiable predictions, yet keeps expanding to accommodate failure.

Because a lot of people felt this applied to them (this was the intention) and were hurt. Good on you for being able to articulate it. Respect.