1,862 karma · joined June 19, 2020
That should be 'edge', not 'face', no? Otherwise I do not understand what is happening at all with the examples.
No they do not.
In fact, authors cannot even delete submitted papers after they have officially appeared in the (approximately) daily cycle. You can update your paper with a new version (which happens frequently) or mark it as withdrawn (which happens rarely). But in either case all the old versions remain available.
S = - sum_n p_n log( p_n )
where the p_n is a probability distribution: for n = 1...W, p_n >= 0 and sum_n p_n = 1. This is always the underlying equation, the only thing that changes is the probability distribution.
And in any case, the fine does not seem to be about the blue checkmarks at all.
https://scienceintegritydigest.com/
Alternatively, maybe the people behind the Data Colada blog can help:
https://www.newyorker.com/magazine/2023/10/09/they-studied-d...
Technical details of the fraud can be found in four famous-ish blog posts of the Data Colada group, also from 2023, beginning with:
"Having a democratic mandate" is either a valid counterargument or it is not. But it is simply not consistent to apply it only to Netanyahu and not to Trump.
So there is at least (and, perhaps, also at most) a sociological difference.
Pet peeve: don't say "are Majorana particles", say "have a Majorana mass term".
All spin 1/2 fermions in four spacetime dimensions can be constructed from the chiral (or Weyl) representation. A Dirac fermion is two independent chiral fermions. A Majorana fermion is just a chiral fermion written in a funny way. And people saying that chiral fermions cannot have mass are lying. (/rant)
By the way, a nicer explanation for the neutrino masses is the so-called seesaw mechanism:
https://en.wikipedia.org/wiki/Seesaw_mechanism
In this wiki article the Majorana mass is denoted B'. However, as the article explains, it must vanish by gauge invariance in the standard model.
That would be exactly my verdict of any product based on LLMs in the past few years.
P(max(X1 ... Xn) < x) =
P(X1 < x and X2 < x ... and Xn < x) =
P(X1 < x) P(X2 < x) ... P(Xn < x) =
x^n
Also,
P(X^{1/n} < x) = P(X < x^n) = x^n
I guess I am just an old man yelling at clouds, but it seems so strange to me that one would bother checking this with a numerical simulation. Is this a common way to think about, or teach, mathematics to computer scientists?
I disagree: some experiments are just not worth our time. I wrote about such a situation three years ago:
https://news.ycombinator.com/item?id=26656206
My view is that it applies here as well.
You refer to a non-scientific article and to a youtube video, but any vaccine sceptic can probably easily find exactly the same kind of material to support their view. That would almost certainly include a video by a "professional doctor".
You might call me abrasive, but I am really just trying to be as clear as possible: this is the consensus in the field.
And before you continue this discussion it might be worth pondering the following questions. How do you think doctors should convince vaccine skeptics that vaccines work? And how big a percentage of their weekend do you think they should spend engaging on the details with anti-vaxxers? (And, in this forum, how many downvotes from obvious non-experts should they be willing to accept?)
In other words, what could I do to convince you in a reasonable amount of time?
MOND is just some wild idea, but a little thought should convince every physicist of its uselessness. It has major issues both in explaining experimental data and in its theoretical consistency. It justifiably receives next to no attention from the vast majority of (astro)physicists.
In popular science the idea however does not seem to want to die, perhaps because it is so easily explained to a layperson. Of course this is a little frustrating for the community, but perhaps we should look at the upsides: more attention for science is probably a good thing, and explaining to people why MOND is so useless provides a good opportunity to discuss some proper physics.
I do not think that is correct? This actually shows stagnation for at least 2 decades in real median household income:
https://en.wikipedia.org/wiki/Household_income_in_the_United...
Source: https://en.wikipedia.org/wiki/Household_income_in_the_United...
For those who know quantum mechanics I would add that the oscillations mentioned in the article are just the familiar exp( i E t ) of any wave function that is an eigenfunction of the Hamiltonian. For a particle at rest in a relativistic theory (and in units where c=1), we of course have E = m.
At times the going is tough even if you are a physics professor, because Pais accurately captures the process of discovery which was often messy with unfamiliar equations, strange logical jumps, or subtle mistakes.
I would not recommend the book unless you have taken courses in quantum mechanics, statistical physics and general relativity.
(Historically quantum mechanics and statistical physics were developed together, even though now we see one as more fundamental than the other.)
Why is this important? Do you think he would not have been arrested if he had not had a French passport? I would think that all that matters is that his crimes fall under French jurisdiction.
Let me chime in that as a physicist (who does use the "pseudo" stuff occasionally) I very much share this opinion.
The notation may be really cool and compact, but I just do not see the benefit - for example, d*F = j and dF = 0 is compact enough for me.
It is all fine if people use this language to learn linear algebra or differential geometry. And maybe it has a use for numerics or computer science. But I am quite sure that the geometric algebra formalism will not be widely adopted in physics any time soon. Sorry.
I am asking this because HN neems to be so much more negative of academia than what I am seeing around me.
More generally I think it is worth stressing that any site like this can be a terrible echo chamber at times. Generally there are smart people here, but on some topics I suspect that the consensus could be completely misguided.
I would like to add that Sabine's video on her academic experience was quite a tragic thing to watch. If her allegations are true then the behavior of her PhD supervisor was completely outrageous.
She also did seem a bit too dreamy-eyed about academia. Sure you can criticize everything you want, but she never seemed to have understood that tone of voice still matters. Academics are busy people with emotions, and not likely to engage with someone whose claims appear to have more loudness than substance.
I insist that calling them "just functions" is simplistic. In fact, I'd say that the complexity of your elaborations kind of proves my point.
Note that I deliberately use "simplistic" and not "wrong", since a section is a function of sorts.
I think this is far too simplistic, for one because the values of this putative function depend on the chosen coordinate system.
So I completely agree with the comment you are replying to: when a physicist says "tensor" they really mean a "tensor field" and the definition of the latter is quite a bit more involved than just specifying a multilinear map at each point of a manifold.
Ultimately physicists care not about the words but rather about the equations. Only equations allow them to predict the outcome of experiments (at least probabilistically). A physicists' ultimate dream is to find a single set of equations that predicts every experiment. Words are just used to describe what the equations do, to colleagues and laypeople alike.
So yes, our best model to describe gravitational phenomena is general relativity which describes these phenomena in terms of the bending of spacetime.
If you want to go back to a "force" description of general relativity you can do so as it's a free world. The description of all the other forces starts with a fixed background spacetime, so to do the same with gravity you'll have to contort the elegant covariant equations of general relativity into an ugly mess by expanding around such a background. And then your resulting "theory" will predict exactly the same experimental outcomes as general relativity. (Around flat space it is not so difficult, it produces Newton's law of gravity to the first approximation.)
All that just does not seem worthwhile. More importantly, the discovery of general relativity (and of the importance of general covariance) led to a paradigm shift in physics: all reasonable physicists now believe that any fundamental theory will not ultimately be a set of equations on a fixed background spacetime but rather a set of equations from which spacetime itself should somehow emerge. Very different, therefore, from quantum field theory which needs a fixed background and describes all the other forces in the standard model.
This was my attempt at addressing the "not like the other forces". For the quantum dynamics see the sibling comment https://news.ycombinator.com/item?id=41179419 . And thank you for teaching me about the "permanent" and "immanant" of a matrix, but I still have no idea what that comment is supposed to mean - sorry.
Obviously one first introduces the relevant probability distributions (at least the micro-canonical ensemble). But once you have those, your comment still does not offer a better way to introduce entropy other than what I wrote. What did you have in mind?
In other words, how did you think I should change this part of my course?
I simply do not understand why you say this. Entropy in physics is defined using exactly the same equation. The only thing I need to add is the choice of probability distribution (i.e. the choice of ensemble).
I really do not see a better "definition of the concept of entropy in physics".
(For quantum systems one can nitpick a bit about density matrices, but in my view that is merely a technicality on how to extend probability distributions to Hilbert spaces.)