does a really nice job of the •commit• workflow: showing the diff, selecting changes to commit, maybe selecting individual lines.
I don’t care about anything fancier that commits — not even branches! I have tools I like for all that stuff.
I’m just looking for a nice UI for viewing and selecting uncommitted changes, something better than the clunky “stage / unstage” buttons that are the norm.
@JimPropp Does it have a lot of credibility? When Robert Krulwich was on, I thought there was a lot of woo-woo being discussed, and I haven't really heard much to change my opinion of that.
No. Succeeding in love is not easy, and there's no formula for it.
Here's the essence of this bad take:
"Since life is itself simply a game in disguise, having a few mathematical tricks up your sleeve can also give you an edge in the game of life."
Life is not simply a game in disguise. There are no fixed rules, apart from possibly the laws of physics. More importantly, there's no fixed definition of what counts as "winning". In fact the whole concept of "winning" doesn't apply, except in very limited realms.
I'm reminded of an anecdote I heard from the statistician Persi Diaconis. I'll probably get the details wrong, but it goes something like this:
Persi Diaconis was friends with an economist who had just gotten two job offers, one on the east coast of the US and one on the west coast. The economist was having a lot of trouble deciding which offer to take: each had its pros and cons. So Diaconis said "Hey, why not use the mathematics you're always talking about? Compute the expected utility in each case, and pick the offer that maximizes it!"
And the economist said "Come on, Persi! This is SERIOUS!"
@johncarlosbaez I'm reminded of a piece of advice I once read and sometimes call upon:
If you find yourself stuck between choosing two options, flip a coin -- not for the result, but to clarify which one you're subconsciously rooting for as the coin spins in the air.*
I don't bring this up as an example of how to "gamify" life, but rather as a way of indicating how, despite being able to methodically rationalize and enumerate the pros-and-cons of any course of action, we can fail to take into account our irrational reactions to the outcomes -- the feelings which we can't always ignore or bury once we have made a choice, and which can haunt and torment us for long after.
(* Of course, that option is a function of how naturally willing you are to leave your comfort zone; the less adventurous/more risk-averse you are, the more likely you're hoping for the outcome that's less difficult in the short run.)
Voice Of Harold
It's The End Of The World As We Know It
Kohoutek
I Believe
Sweetness Follows
Me in Honey
So. Central Rain
You Are The Everything
(Don't Go Back To) Rockville
Pilgrimage
Exhuming McCarthy
King of Birds
Let Me In
Driver 8
Strange Currencies
Romance
Fall on Me
This is the 3rd time I've seen someone who makes YouTube videos go mad trying to second guess "the algorithm."
YouTube provides creators with a firehose of data: How long people watch, when they stop watching, the distribution of views.
YouTube also sometimes selects videos using a secret, unknowable algorithm to be "promoted." For small and medium creators this is a huge deal and the difference between 500 views and 500,000.
For self-critical analytical minds it's a toxic combination. 1/
@futurebird@paulcox I absolutely hate this. There are a lot of video creators who produce quality stuff, not always on serious topics, but who say they are forced to put up a thumbnail image of them looking like Munch's Scream (with added googly eyes). It's not that they're normally dour and stuffy people, but it makes them look like utter clowns. I find it so off-putting that I find it hard to believe that it draws in a significant number of viewers.
Can you roll a ball with exactly enough energy to reach the top of a dome, and have it reach the top in a finite amount of time?
I'm going to idealize the hell out of this problem so we can easily study it using math. So: no friction, no air resistance... in fact, NONE of the sneaky stuff you're probably thinking about!
The problem is still tricky. For an ordinary dome the answer is no. If the ball has just enough energy to make it to the top, it rolls slower and slower as it gets near the top, in such a way that it never reaches the top.
But if the dome has a carefully chosen shape, the ball can reach the top in a finite time! This was pointed out by the philosopher John D. Norton, so it's called "Norton's dome".
Norton was mainly interested in another freaky feature of his dome. Say you start with a ball at rest on top of the dome. Then there are many solutions of Newton's law
F = ma
In one the ball remains at rest on top of the dome. But in others, it starts to roll down the dome in some arbitrary direction! Moreover it can start rolling at any time.
If you change the shape of the dome ever so slightly, this probably won't work. It needs to be crafted with perfect accuracy. So this is basically just a mathematical curiosity.
Math folks will realize what's going on: not every first-order differential equation has a unique solution given its initial value. But Norton, being a philosopher of physics, manages to make this a lot more exciting than a typical textbook treatment of the Picard–Lindelöf theorem. 🙃
@johncarlosbaez@SylviaFysica Interesting! I initially had an intuitive guess that this would take an infinite amount of time in general.
Then I thought about time-reversal and thought it was just the T-reverse of releasing the ball with zero initial velocity -- but I guess the point here is that the top of the dome is an unstable equilibrium point, and only a perturbation to the EOM (i.e. some small but finite push) will cause it to roll down?
Then I confused myself more and thought about the toy picture of instantons and tunnelling. In the Euclidean version of the particle in a double-well, we have inverted the usual potential to get two hills/domes separated by a valley. The "bounce" solution to the Euclidean EOM is where the particle starts at one peak, rolls from down and the up to the other, before returning to the top of the first hill.
But I guess that's still consistent with the above reasoning, as the bounce solution takes an infinite amount of time.
@johncarlosbaez Thanks! I see: the divergence comes from the integral for the travel time taking the form [\int_0^{D} dx/x^{p/2} ].
Though I guess the differentiability at $r=0$ is a more subtle issue, right? Taking $V=-r^p$ with $p=5/2$ for instance meets the criterion for infinite time but should have the same differentiability issue as $p =3/2$.
@johncarlosbaez Well, some of us might be getting paid to do so, while others are a little rusty... ;-)
I guess here analyticity doesn't matter as long as it's smooth, which implies (IIRC) that it's Lipschitz continuous, which apparently is the relevant criterion? But I suppose a more precise specification is described in the reference (and its citations) provided by Sylvia.
@johncarlosbaez Thanks for engaging again! I see, to find more such solutions we know where to look but have to take it case by case. Maybe there is also some minor issue regarding changing variables to the arc-length coordinate as per my edit above, but I guess in general the RHS of the ODE will have the same properties for smooth changes in variable.
Things like Picard-Lindelof, and Cauchy-Kowalewski, are theorems that I briefly passed by while learning something in lectures or checking if some result was kosher -- I had a slightly unconventional route through physics and a bad head for names, so this read as Picard-Lefschetz at first.
@supernovae Very sorry to hear this -- my best wishes to you and your family. Thanks very much for setting up this instance, which allowed me to take my first steps in the Fediverse.
Physicist Rudolph Peierls was born #OTD in 1907. He contributed across the breadth of 20th century physics, from quantum field theory to nuclear physics to statistical mechanics.
Peter Woit exposed the problems with string theory. Then Sabine Hossenfelder brought the news to a bigger audience. Now, in this hilarious video, Angela Collier brings it to the Gen Z gamer crowd:
Yes, she shreds the repeated grandiose claims of string theorists while gaming!
I agree with her main points. Some pedants (like me) will notice mistakes. I think they arose because she has a PhD in astrophysics, not particle physics. Also, she said she didn't want to talk about the physics, just the sociology. None of these mistakes affect her actual point, but just to keep up my nerd cred:
The pion was not one of the particles whose existence was predicted by the Standard Model. Yukawa predicted it way back in 1935, and it was found in 1947.
The cost of the never-finished Superconducting Supercollider would have been $11 billion, not $200 billion. I think she was just being flip here. By the way, the US spent $2 billion building it before giving up.
There are 5 superstring theories, not 10.
Bosonic strings work best in 26 dimensions, not the numbers she haphazardly guessed.
A bit more importantly, I think she said the Superconducting Supercollider was cancelled much later than it actually was: October 1993. So this gums up her chronology a bit.
@johncarlosbaez I think I know a little bit about your background in LQG/QSG, but I'm curious as to how your animosity to string related work has grown.
I agree that the era of hype around the 90s (slightly before my time) was not at all helpful, but in my view there are still some interesting and useful things arising from the field -- though perhaps we can argue about the distinction between science, mathematics etc.
I've seen some interesting papers of yours on SUSY in the past (though these approach it from the mathematical rather than pheno. side), and a lot of your recent posts on line bundles, sheaves, abelian varieties and algebraic geometry all cover topics that arise frequently in the string theory literature -- some of the questions you raise are often discussed there. Maybe you won't appreciate this, but you have a lot in common with the string theory community!
@johncarlosbaez That's not the impression you give! I recall a post from you here about "people doing better stuff than strings/SUSY", which is fair enough.
The video's 52 minutes long, and as someone who's worked in string related pheno and cosmology, I think I can hazard a guess at some of the points raised based on your description of her "shredding repeated grandiose claims".
By the time I got into the field -- which is post-LHC -- I didn't really get a sense of grandiosity from my the older hands. Most of them were seemed more than slightly embarrassed by the situation.
@johncarlosbaez My take on this is that this entire era from the 80s-mid 2000s was one of global hubris. In the same way that the political world had seemed to reach "The End of History", I think that generation of physicists arrived at the rich structure of string theory and felt that "The End of Science" (i.e. the ultimate theory) had been achieved. In both cases it hasn't worked out that way.
My fear is not whether or not string theory will survive as a field -- whether it does or not, I think whatever succeeds it will still be influenced and shaped by it -- but whether particle physics in general will continue.
@johncarlosbaez I think that while the string hubris of the 90s may have "made science communication difficult", the reach of its critics like Woit and Hossenfelder is in danger of making HEP devalued. Not because of what they say specifically (although Hossenfelder seems happy to let large HEP experiments die), but because the public and policy makers will not be able to see the difference between strings and HEP in general.
(If that's the point that's made in the video, then my apologies.)
@johncarlosbaez I see, I'm sorry for mischaracterizing the sentiment (though I think such a post exists, as I was struck by the impression it left on me).
I'm afraid that I have to agree with pretty much everything you said. Condensed matter and quantum info/computing may be more fruitful and rewarding areas to direct younger people towards than HEP.
But I think there is still useful and interesting work being done there, despite all the problems. I fear that the sense that this is all "uninteresting nonsense" and a "waste of time" (not your words) will take hold, when in fact it's bloody difficult.
Maybe a collective step back is warranted. But I'd hate for it to be for the wrong reasons.
@johncarlosbaez Tell me about it! If only we could come up with a catchy name for the intersection of math and physics... ;-)
The way I try to think about this is that, in the absence of new data (particle states or other new physics detected by experiment), the role of mathematical physics is to get some sense of what could be possible in nature (subject to internal consistency), and to better improve/organize what we currently know by developing new tools and techniques.
I see examples of the latter in how stringy and SUSY related math is being used in the calculation of scattering amplitudes. For the former, I'm thinking along the lines of the Swampland conjectures, or studying SQCD to understand confinement, or the various mechanisms in string-descended models of inflation (pace Steinhardt et al.).
(I'm sure you know all this, I'm mostly just affirming it to myself and to anyone else who's following this thread!)
The usual name for inverse hyperbolic sine function is
arcsinh 𝑥
Now some Wikipedians have decided to start calling it
arsinh 𝑥
I've never seen this before and it makes me think "arse". I don't like it!
A more common alternative is
sinh⁻¹ 𝑥
Some computer scientists use
asinh 𝑥
Some pedants, claiming that hyperbolic trig functions aren't connected to arcs, argue for
argsinh 𝑥
Who came up with "arsinh" and why? Is it too late to kill off this notation? It seems like a case of Wikipedia editors run amok. It reminds me of how some of them made up their own very precise definition of "order of magnitude" - and now run around correcting people who say "to within an order of magnitude" if it doesn't match their made-up definition.
When I want to be understood I'll use "arcsinh". When I want to act mathematical I'll use "sinh⁻¹". If I wanted to save space I'd write "asinh". I might use "argsinh" if I were pretending to be a pirate. But I'd only use "arsinh" if I wanted to be an arse.
By the way, I don't like debates about notation. So I don't know why I'm talking about this when I have more interesting things to talk about. Just blowing off steam, I guess.
@johncarlosbaez I believe this was the convention in UK schools -- though I don't recall being particularly titillated by "arse" when learning about it. See for instance the following book (Chandler, S.,Rourke, C.,Bostock, L. (1982). Further Pure Mathematics), whose heydey was before my time, but which we consulted when the more modern ones ran out of exposition:
And the absence of the 'c' was explained precisely by the argument you gave. The avoidence of the inverse function "exponent label" (^{-1}) was to avoid students confusing it with the reciprocal (as with arcsin).