Steuard

40 ms·

301.
by Steuard 11y ago
True. I started using Subversion and then Mercurial for writing scientific papers during grad school (a distributed VCS was handy when editing on multiple machines), but it never seemed worth the effort to teach my collaborators how to use
302.
by Steuard 11y ago
At the University of Chicago, the thesis office didn't give any indication that they'd ever heard of LaTeX. But they did hand us a long list of formatting requirements (precise margins, contents format, lots of other details) and
303.
by Steuard 11y ago
I've been a professor for close to ten years now, and I can't tell you how strongly I disagreed with this essay. Maybe it's a generational thing: a perception of what's acceptable in life even outside academia. For insta
304.
by Steuard 11y ago
I'm not sure that I know which way you mean that initial comment. I don't see there being any question that "SJW" is almost always intended as an insult: it's almost universally used by people who disapprove of that
305.
by Steuard 11y ago
It's a pejorative term meaning "social justice warrior", almost invariably intended as an insult. In my experience, there's no well-defined meaning to the term (it covers a lot of ground), but it does send a pretty consi
306.
by Steuard 11y ago
> people are not being locked up just because they are black, or poor I just said this elsewhere, but I knew many people in college who used illegal drugs, and none of them were ever locked up (or even searched). When we have a set of
307.
by Steuard 11y ago
I knew quite a few people in college who used illegal drugs, some of them pretty regularly. (I doubt that I'm the only person for whom that's true.) That is crime. To my knowledge, not one of them were ever investigated, searched,
308.
by Steuard 11y ago
I should've guessed that you had a physics background, since that turned out to be an unexpectedly interesting problem. (The view from one of the moving rods in particular was more subtle than I anticipated. As usual, once I stopped tr
309.
by Steuard 11y ago
So, do I understand you correctly: relative to the "static observer", the rods are both moving "sideways", as if the x-axis of a graph were moving toward +y and the y-axis were moving toward +x? In that case, the "s
310.
by Steuard 11y ago
As you say, event order is not preserved: two events that appear simultaneous to one observer can easily appear in different orders to other observers. But causality itself is safe in relativity: if a signal from event A could possibly
311.
by Steuard 11y ago
If you've got way too much time to spare, I've got a set of topic review videos that I made for various classes on this stuff. The quality's not great , but seeing some worked examples could be interesting. https:/&#
312.
by Steuard 11y ago
This explanation is correct, but I find it pretty empty of intuition: "Here's a magic formula! Look, it adds up funny." I've taught relativity quite a bit recently, and I much prefer to build intuition using "space-
313.
by Steuard 11y ago
That's still a built-in Firefox feature: View->Page Style->No Style. The same menu will also let you choose between different "alternate style sheets" for the same site. (I think it may even be sticky, per-page or per-s
314.
by Steuard 11y ago
It doesn't work, or so I've heard. Drivers in those cities learn to expect the safety margin of the delay, and statistically they become more willing to run a red light right after it changes.
315.
by Steuard 11y ago
I honestly don't even know where to begin in responding to this. You've called me (or my words) "ignorant" and "pseudo-skeptic", you've suggested that I have relied on appeal to authority in making my argu
316.
by Steuard 11y ago
I can't begin to tell you how much more likely I would consider a lunar McDonald's publicity stunt than a demonstration that "momentum isn't conserved after all". The first is so implausible as to be laughable. But
317.
by Steuard 11y ago
Well, that's a funny question, right? On the one hand, they really were careful in their announcement to indicate "we're not sure about this". They were clearly making a real attempt to exercise proper scientific skeptic
318.
by Steuard 11y ago
Conservation of momentum can be derived as a necessary result in any theory whose basic laws are translation invariant (that is, if the defining equations are unchanged if you move everything in the universe 6.2 cubits to the left). This
319.
by Steuard 11y ago
Nope! :) That's the point of the "locally conserved" clarification I made in a sibling comment: these conservation laws hold at every individual point in space, regardless of whether the point is part of a curved manifold or
320.
by Steuard 11y ago
I may have been using a technical term too glibly there. Local conservation of momentum is a fundamental property of any translation-invariant model in the framework of quantum field theory. All this means is that the (vector) momentum flow
321.
by Steuard 11y ago
I guess this is really the point: space elevators and commercial fusion are many, many orders of magnitude more likely to pan out than this is. Both of those are engineering challenges, and materials science challenges. They may be insurmou
322.
by Steuard 11y ago
And even low-Tc superconductors looked "impossible" under the physics of their day. No question about it! Science thrives on surprises: it's the very best part of what we do. But maybe non-physicists don't have a sense o
323.
by Steuard 11y ago
Yes, it would be more precise if I had prepended "local" every time I said "conservation of momentum" above. With that clarification, I'm happy to stand by what I've said.
324.
by Steuard 11y ago
I'm not sure what you're getting at, either. The Casimir effect is real, absolutely. I think it was an exercise in one of my quantum field theory classes. In particular, the Casimir effect is something that you can compute entirel
325.
by Steuard 11y ago
Yes, actually. Every dollar that NASA spends has the potential to accomplish something for humanity. To my eye, even the vast potential benefits of this technology are more than washed out by the tremendously low probability that it will tu
326.
by Steuard 11y ago
Fair point, and thanks for calling me on it. In retrospect, accurate or not, that sentence grew out of feelings of frustration more than a desire to teach, which is always a bad sign. I've rephrased it. (I really do have much the same
327.
by Steuard 11y ago
Yes, sure, they've measured something surprising. I have no reason to doubt that. A few years ago, the enormously more respected folks at the OPERA experiment were willing to announce that they had seemingly detected neutrinos moving f
328.
by Steuard 11y ago
In the back of my mind, I suppose I'm hoping that some administrator involved with the NASA budget is reading my comment. (Just for instance, I would say that the possibility that we could find life on Europa or the other outer moons i
329.
by Steuard 11y ago
This is not worth getting excited about. Really. Extraordinary claims require extraordinary evidence. These drives would violate conservation of momentum.[0] Conservation of momentum is built in to the known laws of physics at an extraordin
330.
by Steuard 11y ago
A friend of mine created the board game Robot Turtles ("programming for preschoolers"), which has a bit of that goal. It's a parent-child(ren) thing rather than a solo activity, mind you. http://www.robotturtles.co

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