| HN Mirror

If one can extract practical comparisons between a pair of mathematical formalisms, and map those to differences in observables, I think that qualifies both as physical theories. Between ASG and string theory (with some assumptions about how to get the latter out of the AdS box and ignoring the landscape problem) there are noteworthy differences that are likely to manifest in the detailed accounting of accretion disks around astrophysical black holes. QG phenomenologists (who are sadly rare) are professionally interested in extracting such comparisons among various theories with a view to distinguishing them observationally or experimentally.

Annoyingly, experimental evidence can be hard to come by because any viable mathematical formalism has to reproduce the successes of GR, and it is shockingly easy to depart from GR in a serious way even in very weak gravity.

ASG's main anti-features are that it's not in itself a fundamental ToE; what it would accomplish (if it holds up) is getting the gravity part right to Planck scales and avoiding the incompatibility with QFT. Who knows what beyond-the-Standard-Model physics outside the gravitational sector will look like at those scales?

ASG is not alone in this, though.

String theory, on the other hand, would let gravity and matter emerge from something like a field of strings resembling dark energy, where cooling increases the apparent volume of the cosmological frame at a given scale factor. Slow thermalization in turn produces everything else, like dark matter, baryons, light, and so on.

There are other less popular theories from which matter and spacetime geometry emerge, too.

And of course it goes the other way around too, where matter theories can arise from geometry (Cartan torsion is still viable, and Poplawski still tries to get people to pick up Riemann-Cartan geometry; and quantum geometrodynamics remains viable too).

> We live in amazing times

The amazing thing is that collaboration, simulation, and publication is hugely improved upon even a couple of decades ago. If in the early 1900s people had WWW and message boards, email and message boards, LaTeX, ArXiv, and so forth, who knows what might have been different given the big brains around at the time !

In richer countries we have relative peace, antibiotics and sanitation. Feynman's wife died of TB while he was working on the Manhattan project; that's the trifecta there, just once removed from a theoretical physicist. Henry Moseley was shot through the head on the battlefield at Gallipoli. Many other scientists had their work seriously disrupted during both world wars and during cold war repressions (Sakharov on the one hand, Condon on the other; the former got it much worse of course).