zachf

Don’t worry, I didn’t think you were :) you’re welcome!

80 years? I would date its birth as 1968-9 (Veneziano), it’s hard for me to imagine calling prior work than that as “string theory”. But never mind that—the bigger problem with this (quite common) argument is that everything about quantum gravity, not just string theory, has avoided testability because our other theories are too good, and because we’re limited to doing experiments on Earth with equipment built on human scales with human budgets, and that’s just not where quantum gravity would naturally make itself known. So really this argument just suggests we shouldn’t study quantum gravity at all. Maybe that’s your actual opinion—it’s a waste of time if we can’t access the Planck scale, we should table it all and sit on our hands until we can. But string theory really is quite interesting to study, stuff like AdS/CFT is just really surprising and magical when you get what it’s about, and it would be a real pity to not pay the meager salaries of theoretical physics just because of pessimism. String theory is so far from fully understood! It’s actually…really hard!

BtW I think you got this 80 years number from looking at the earliest date on the Wikipedia page. You might want to read it more carefully. Not everything leading up to string theory is string theory.

I mean the people and land area governed by the United States Constitution, a document that provides explicit protections against the kind of ethnostate policies you are so worried about.

Right, of course, extending the franchise of voting to women and non-white, non-landholding men devalued the franchise, lol.

America has a long history of successful integration of racial groups. Once upon a time, the Irish were extremely unwelcome in Boston, simply for being Catholics. Dozens of examples like this abound in American history. America is stronger than the countries you’ve listed because of the melting pot, not in spite of it. That’s because the selfishness you alluded to is contrary to a core American value: that a person is not defined by their ancestors’ virtues or sins, but by the content of their character. All the immigrants I know are fierce defenders of this principle.

It’s a pity some people can’t think of politics as possibly more than zero sum. A good policy should actually lift all boats. Middle America simply will not survive without more people and more economic activity, period. If native born children choose to move to the coasts, and no immigrants fill in the gaps, you’re not going to have the long-term prosperity you’re imagining.

So you would support naturalization of immigrants who agree with your views, then?

I remember hearing that exact phrase, word for word, back in 2008 about gay marriage. Guess what happened next?

Okay, I’ll tell you about my own research. From studying the way that geometric surfaces work in AdS, we conjectured a relationship between the stress tensor of QFT and entanglement entropy. This is because those quantities translate into geometrical analogs in the quantum gravity theory. We then proved this same relationship holds in some simple field theories and then other physicists proved it in the general case. So we learned something about non gravitational physics from gravitational physics. We study a specific, tractable case (AdS, mapping onto CFT) and then use it to learn about the general case (every QFT). That’s how physics works! You study the spherical cows. Eventually you learn something universal. All this is because I started with an open mind, and pursued the full consequences of AdS/CFT.

Your complaint about supersymmetry is like saying that Newtonian physics can’t work because objects are not rigid, continuous solid bodies. And yeah, that’s true, there are none of those in nature. Does that mean Newtonian physics is not useful? NO! It’s a model that’s useful. Is it wrong? Kinda. And the models that have unbroken SUSY are “wrong” too, in the same way. But the point is—-it’s obviously useful!

Please try to be open minded about string theory, especially if you wish to lecture about small-mindedness around MOND. Diminishing the real accomplishments of physicists doesn’t make other fields more likely to get funded—it makes it more likely that bureaucrats defund everyone. That’s the lesson of the SSC.

No, this is a shallow understanding of AdS/CFT. If you want to study quantum gravity when it is weakly coupled to matter, you can use AdS/CFT regardless of whether the background space is asymptotically AdS by embedding a brane near the boundary and working in a perturbative expansion. If you want to study the physics of quantum de Sitter space with a field theory dual, you can study any of the recent work on TTbar deformations. And anyway, surely you aren’t arguing that conformal field theories are irrelevant for physics? Because that would obviously be an untenable position, and the whole point is that quantum gravity AdS (basically) is CFT (it’s an equality! It goes both ways), just in different variables. You can actually study non-gravitational physics with it, using a gravitational language. That’s awesome stuff! Please don’t dismiss this fascinating field too quickly.

By the way, I know Oppenheim personally. He gets funding from string grants. Nobody is angry about that. Anybody can do this. I don’t think his theory is going to pass any experimental validation (it requires a really severe violation of a physical principle we have tested over and over) but the entire community has always supported and listened. He gives talks at major universities. He’s not an outcast or renegade or something.

There are in fact exceptionally strong incentives to discover alternatives to quantum gravity which could be tested in experiments. These are the same incentives that always drive the scientific process, and new theories cost next to zero to produce. The reason string theory is popular is not because string theorists somehow prevent funding of other directions. It is because string theory has given us tools like AdS/CFT that are useful in other contexts to understand real physics—-and the alternatives have not (yet). There are many physicists who spend their lives studying alternatives to string theory with 100% of their time. I hope for their sake that there is a similar pot of gold at the end of their rainbows. It has not yet materialized.

Is your preferred remedy that quantum gravity be entirely defunded, or instead that more funding be redirected to any of the other programs to study quantum gravity? If the latter, which ones in your opinion are more likely to be productive than string theory?