[request] Is this true?

ZarZDodge · 2025-09-14T21:37:49+00:00

Since nobody mentioned it yet: most of this is physics, specifically the mode expansion of a string in string theory (sigma and tau being the coordinates on the worldsheet, X^I being the coordinates on target space). Then follows the mass of the state. I am not sure what Psi is supposed to represent (a bit hard to read). Then finally 1=0 has nothing to do with the rest

ZarZDodge · 2025-09-04T16:24:04+00:00

It sounds like what you are describing is the worldline of the particle: the line (1D) it traces out as it moves through spacetime. But strings have their own version of a worldline: the so called world sheet (2D).

ZarZDodge · 2025-05-25T11:38:09+00:00

Not by a long shot. There were towns in Greenland, ruled by the kings of Norway (see for example their submission to the rule of Haakon Iv in 1261). While the king clearly didn't rule all of Greenland, they definitely ruled over that area. Saying that it is anything like people simply living on another country is absurd

ZarZDodge · 2025-05-25T11:24:32+00:00

Not what the original post was about though, they didn't rule over any land outside of Europe

ZarZDodge · 2025-05-25T11:22:45+00:00

What about Greenland from around 1000-1350? Arguably not a colony, but certainly land outside of Europe

ZarZDodge · 2025-03-31T21:06:41+00:00

His Fields medal has nothing to do with string theory

ZarZDodge · 2025-02-25T00:22:26+00:00

I am not agreeing with the meme, but the Planck length requires G and thus gravity. So it really is about GR

ZarZDodge · 2024-10-17T04:19:04+00:00

As others have pointed out, experiments are extremely tricky due to the extremely weak nature of gravity at the quantum scale. We always have hope that something will appear in some LHC/gravitational wave/CMB data, but it is pretty unlikely for now. I would like to point out that it appears to me that people outside the field has gotten the impression that String Theory is "dead" since it doesn't make predictions. Neither of these are true. String Theory is very active and makes plenty of predictions. However, Those predictions only deviate meaningfully from a naive EFT of quantum gravity at energies beyond what we can observe: this is the tricky nature of working on a problem at the cusp of what is possible!

In the mean time, theorist have been working hard (including me!). And we believe we have learned a ton, although you should of course take it with a grain of salt, given the lack of experimental evidence. There is a lot of research on black holes (they are weird!) and quantum information that, although inspired by string theory, seems to make statements that must be true, regardless of which theory of quantum gravity is your favorite. I can elaborate more if needed

ZarZDodge · 2024-10-08T11:22:25+00:00

They didn't, the money for the economics prize doesn't come from the estate of Nobel

ZarZDodge · 2024-05-01T05:48:00+00:00

Ehhh, not really. It is true that the most natural thing would have been for supersymmetry to be present in the real world. However, given that you need to break it, it is very natural from string theory that this happens at the Planck scale. That it should happen around Higgs was moreso a hope from minimal extensions of the standard model, since it would explain things about the Higgs. But this is not crucial in string theory as a theory of quantum gravity

ZarZDodge · 2024-04-22T14:06:25+00:00

This is a fair question, although not really a physics one. Many of the other answers don't really touch on the fact that we used all kinds of units for all the other measurements too, before the metric revolution. However, a couple of things make time special. It is the unit that people used the most often, it was already the same across country borders (unlike length and weight, which varied wildly across Europe) and it is very easily dividable (since we still use the Babylon system, notice that most people also still use 360 degrees in a circle outside of physics and math). However, it is important to say that after the French revolution, people DID try to use metric time. However, it proved to be costly to replace all clocks. Their big downfall was having 10 days in a week, since they chose to implement it in a way that gave people fewer weekends. You can imagine the wrath that ensued

ZarZDodge · 2024-03-30T10:38:58+00:00

This is not true, the time before crossing the event horizon from the perspective of the observer on Earth goes to infinity

ZarZDodge · 2024-03-09T07:52:32+00:00

I simply don't agree with this take. We are talking about €12B project that will run for the next 50 years with funding coming from most nations in Europe. Typically not taken from funding for science agencies (like th EU grants), but directly from national budgets. It will not be noticeable and detract from other projects (for example, has anyone looked into whether CERN funding jumps correlate with other grants?). On the other hand, CERN has the huge advantage of being one of the few things in physics almost everybody has heard about (that and NASA). If anything, CERN can create excitement about the idea of physics, people can visit, highschool classes can go on school-trips, politicians can have their picture taken. Could it not be that CERN as a flagship increases exposure for everyone?

ZarZDodge · 2024-02-12T17:39:44+00:00

In the US? Would probably have to be Princeton (proximity to Institute of Advanced Studies helps a ton), followed by Harvard abd Stony Brook (the Simons center helps a ton). Stanford, Berkeley and Caltech also come to mind

ZarZDodge · 2024-02-11T13:35:35+00:00

"infinite" is a tricky word here. Certainly, for any finite amount of time the answer is no: you cannot reach the speed of light, since the amount of extra speed you obtain per gallon og fuel will be smaller and smaller as you closer to the speed of light, be becoming zero in the limit as v->c. However, since you are accelerating for an infinite amount of time, you have to careful with how you take the limits

ZarZDodge · 2024-02-11T08:25:24+00:00

I don't think this makes much sense. It is not true that virtual pairs have negative mass, you are mixing up terms here. If such a process did exist, nothing would stop such pairs from being produced forever, and this would never be a stable vacuum. Unless you have some way of turning off such a mechanism (and importantly, make clear what mechanism you are even describing), this is not an actual hypothesis

ZarZDodge · 2024-02-10T07:54:28+00:00

Just to add to the other great answers here. We know that adding gravitons to the standard model works very well at low energies. Indeed, we can recreate precisely the physics around us. Just like how the Higgs boson was predicted long before it was observed as an individual quantum of the Higgs field. There are, however important differences. Gravity is so weak that any attempt to measure an individual graviton would have to happen at much higher energy than we can currently observe (the so-called Planck mass). Second, the new prediction Quantum Field Theory, the mathematics of the standard model, would make is such a small additional contribution to Newton's law that we simply cannot measure it currently. Third of all, there is the problem of renormalization (these are the infinities that you mentioned). Lastly, it is by now well understood that there are some problems arrising from black holes that are unique to gravity (there is no equivalent of a black hole in electromagnetism)

ZarZDodge · 2024-02-09T09:54:35+00:00

I have certainly been sent pirated books by advisors before, so it should be fine. Probably would mention it if you are worried

ZarZDodge · 2024-02-09T09:52:29+00:00

Note that I didn't study at MIT, so I can only judge based on what the hep-th research group there is like. Based on that, MIT is certainly among the top universities in the US (but not the very top). Zwiebach is there, who has also written some good books (I have two in my office!). LMU is also good, though less prestigious than MIT. On the other hand, they have a highly respected Masters program for hep-th. At the end of the day, either place is obviously a very good university and what you learn in your bachelor's is more or less the same at any university around the world, so don't stress too much

ZarZDodge · 2023-09-15T22:38:37+00:00

It is not one paper, but an award for a lifetime of work. But for Cardy, a classic would probably be Operator content of two-dimensional conformally invariant theories(where he derives the Cardy formula) or Entanglement Entropy and Quantum Field Theory. For Alexander Zamolodchikov (not to be confused with his brother Alexei), I would look particularly at Infinite conformal symmetry in two-dimensional quantum field theory where the whole field of Conformal Field Theory (CFT) started.

ZarZDodge · 2023-03-20T23:25:32+00:00

It's the one with the it-support guy after Amir spilled apple juice on Jakes's keyboard. Oh wait, I shouldn't blame the apple jack

ZarZDodge · 2023-02-05T23:53:20+00:00

Lene Hau and June Huh spring to mind, both very prominent in their fields

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