zachf

6 ms·

1.
by zachf 2y ago
Don’t worry, I didn’t think you were :) you’re welcome!
2.
by zachf 2y ago
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
3.
by zachf 2y ago
The kind of supersymmetry you’re referring to (global spacetime supersymmetry) is not required by string theory; this is a common misconception. Looking for super partners in a collider is actually only telling you about global supersymmetr
4.
by zachf 2y ago
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.
5.
by zachf 2y ago
Right, of course, extending the franchise of voting to women and non-white, non-landholding men devalued the franchise, lol.
6.
by zachf 2y ago
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
7.
by zachf 2y ago
So you would support naturalization of immigrants who agree with your views, then?
8.
by zachf 2y ago
I remember hearing that exact phrase, word for word, back in 2008 about gay marriage. Guess what happened next?
9.
by zachf 2y ago
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 g
10.
by zachf 2y ago
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 ne
11.
by zachf 2y ago
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 t
12.
by zachf 2y ago
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
13.
by zachf 2y ago
You would probably learn more by listening to Cumrun Vafa [0] than anything I could say. It’s hard to say much about string theory without space time supersymmetry not because it doesn’t exist (we know it does) but because it’s so hard to c
14.
by zachf 2y ago
You mean, if string theory does not turn out to describe the universe, how could it be useful? Well, by giving extraordinarily powerful tools for understanding things that are well established to be useful, like quantum field theory. AdS&#x
15.
by zachf 2y ago
If you have something specific in mind, I’m happy to address it! But I’m not quite sure what you’re referencing.
16.
by zachf 2y ago
To whom? To other branches of physics? Look up AdS/CFT. To the general public? Dunno, I guess the pursuit of understanding the universe is its own reward for some.
17.
by zachf 2y ago
There are exactly zero free parameters in string theory [0]. The details of why string phenomenology is hard is a difficult subject, but the characterization you've given of it is not correct. If you have a proof that string theory is
18.
by zachf 3y ago
Most quantum computer experts think that this is not the case, that it is very unlikely that quantum computers can solve NP-complete problems like travelling salesman more efficiently than classical computers. (In particular, the popular in
19.
by zachf 3y ago
This is one of those things that laymen often misunderstand, actually. (I don’t blame you, it’s often not well explained.) General relativity is easy to make into a QFT. There’s an action and you can easily derive amplitudes from it. And it
20.
No, physicists didn’t make a real wormhole. What they did was still pretty cool(arstechnica.com)
2 points by zachf 4y ago|0 comments
21.
by zachf 4y ago
I think it proves my point that AdS/CFT is hard to talk about :) I’ve still got mixed feelings about the lamp/shadow analogy but thanks for the clarification.
22.
by zachf 4y ago
Respectfully, your metaphor doesn’t bear any similarity to the way AdS/CFT works. In AdS/CFT there are dual quantum systems with no information loss. A bit more precisely, the correspondence relates the partition functions of quan
23.
by zachf 4y ago
If anyone is looking to learn some actual physics instead of media crit, it would be worthwhile to sit down with the wikipedia pages for the AdS/CFT correspondence and the black hole information paradox. There’s a lot of things you can
24.
by zachf 4y ago
Newtonian space == a universe with nothing in it, which is then populated with fictitious continuous rigid bodies. Yet we use it to build bridges. Physics is about models. Some are useful. AdS/CFT is useful. I know this because I spent
25.
by zachf 4y ago
Since this comment was more controversial than I expected, let me add a few notes. 1. Everything done on the quantum computer here can be (and was) also simulated on a classical computer. The most interesting part of the story here is the a
26.
by zachf 4y ago
This is a very cool and important result. Here's a rough analogy to what's happening. You take two drums, and you hit one of them. Then you wait for a while. After waiting, you hook up a special kind of wire between the drums, and
27.
by zachf 4y ago
Its the part that you omitted from your summary that makes the statement nontrivial—the idea that the metric theory (poetically, the warping of space) is only valid as a low energy effective description, and the general case does not have a
28.
by zachf 4y ago
You might be excited by [0]. The idea there is to study a novel phenomenon in strongly-coupled quantum systems that is very complex to see ordinarily, but becomes easy to understand when you look at the same physics from the gravitational p
29.
by zachf 4y ago
The existence of those solutions is independent of a choice of coordinates. (Nothing in GR is ever allowed to depend on coordinates, in the end!) The existence of the second asymptotic region is easiest to see from the Penrose diagram of th
30.
by zachf 4y ago
One of the most important papers in this field is [0]. (As is common in science, it built on a long history of nearby ideas, e.g. [1].) An important calculation done around this idea is presented in [2], in which remarkable progress is made

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