5 ms·

Tadashi is awesome! I love his video explaining how someone found a prime that looks like the Arms of Trinity Hall [1]. Highly recommend all videos from Numberp

by luisb 9y ago

Tadashi is awesome! I love his video explaining how someone found a prime that looks like the Arms of Trinity Hall [1]. Highly recommend all videos from Numberphile [2] and Fermat's Library [3]. [1]https://www.youtube.com/watch?v=fQQ8IiTWHhg https://www.youtube.com/watch?v=fQQ8IiTWHhg [2]https://www.youtube.com/channel/UCoxcjq-8xIDTYp3uz647V5A https://www.youtube.com/channel/UCoxcjq-8xIDTYp3uz647V5A [3]https://www.youtube.com/channel/UCSD2RxaYn2Nxkm41gp-eKfA https://www.youtube.com/channel/UCSD2RxaYn2Nxkm41gp-eKfA

imglorp 9y ago
If you aren't convinced rolling downhill is complicated, physicist Walter Lewin has a demonstration involving cylinders, no fluids this time. https://www.youtube.com/watch?v=cB8GNQuyMPc https://www.youtube.com/watch?v=cB8GNQuyMPc
- arbie 9y ago
  That was incredible. Every combination hypothesized, then experimented with, ending with an intuitive explanation.
  - lisper 9y ago
    I'm afraid I have to dissent here. Compare the footage at 2:10-2:15 with that at 3:20-3:25. He wants the result to be that the box starts sliding at the same angle in both cases, and that's what should happen if what they teach in physics 101 is correct, but that is not actually what happens in the video. In fact, the box starts to slide noticeably earlier in the second case (which is exactly what the off-screen crew members predicted). But he simply glosses over this and says "within one degree the same". What is what should have happened, but is not what actually happened. This is a very unscientific attitude, and I think this does a tremendous amount of damage to the popularization of science, particularly in the face of accusations that science is just another religion with its own dogmas, high-priesthood, etc. The correct reaction here would have been, "Hm, that's interesting, it started sliding earlier. That's not what I expected, and is not what theory predicts. Let's see if we can figure out why this happened." It's also kind of lame that we have to rely on his callouts to know what angle the board is at. It would have been trivial to set up a pointer that would have been visible to the camera. P.S. Yes, I know that he "explains" the discrepancy at 3:40, but his explanation is bogus. First, the discrepancy is much bigger than the "half a degree" that he explains away. And second, his explanation is actually a hypothesis that is easily tested: just run the experiment multiple times. He could easily have done this and again demonstrated how science is actually supposed to work, but he didn't. P.P.S. He does it again at 7:02 where the longer cylinder is clearly beating the shorter one by nearly a full cylinder radius right before he proclaims "no difference".
    - baddox 9y ago
      I understand your complaint, but this isn’t a formal proof or a research paper seeking peer review. This is an educational demonstration of physics concepts that have already been very well-established through the much more rigorous methodology and peer review you are asking for. Of course the educational demonstration won’t have the same rigor, and it shouldn’t be expected to.
      - sago 9y ago
        With respect, I don't think that was his complaint. The problem is pretending to demonstrate by experiment something that involves abstractions to the real world. It's the same thing with 'demonstrations' that a heavy object will fall at the same speed as a light object where inevitably its 'close enough,' but not actually true (they do in perfect vacuum, but not in a simple experiment). This happens a lot in demonstrating science, because science is really messy. And even relatively simple physical phenomena we don't understand fully (a recent topical example is we don't properly understand why curling stones curl the way they do). The problem is pretending the answer is simpler than it is. Which inevitably leads to motivated 'pseudo-experiments'.
        lisper 9y ago
        > The problem is pretending to demonstrate by experiment something that involves abstractions to the real world. Not quite. My complaint is pretending that the result of an experiment was something other than what it clearly was and saying, implicitly, "despite the fact that you could plainly see that the result of this experiment was NOT what I said it would be, you should nonetheless believe what I tell you about the laws of physics because I'm the professor and you are the student and I know what's what and you don't. Pay no attention to the actual outcome of the experiment that you saw with your own eyes and instead trust my authoritah." > This happens a lot in demonstrating science, because science is really messy. That's no excuse here IMO. In this case the demo was simply very poorly designed. It's just not that hard to construct a friction and moment-of-inertia demo that actually shows what it is intended to show.
mistermann 9y ago
Tadashi playlist: Tadashi Tokieda: https://www.youtube.com/playlist?list=PLt5AfwLFPxWI9eDSJREzp1wvOJsjt23H_ https://www.youtube.com/playlist?list=PLt5AfwLFPxWI9eDSJREzp...
deleted 9y ago
[deleted]

by luisb 9y ago

imglorp 9y ago

If you aren't convinced rolling downhill is complicated, physicist Walter Lewin has a demonstration involving cylinders, no fluids this time. https://www.youtube.com/watch?v=cB8GNQuyMPc https://www.youtube.com/watch?v=cB8GNQuyMPc

arbie 9y ago
That was incredible. Every combination hypothesized, then experimented with, ending with an intuitive explanation.
- lisper 9y ago
  I'm afraid I have to dissent here. Compare the footage at 2:10-2:15 with that at 3:20-3:25. He wants the result to be that the box starts sliding at the same angle in both cases, and that's what should happen if what they teach in physics 101 is correct, but that is not actually what happens in the video. In fact, the box starts to slide noticeably earlier in the second case (which is exactly what the off-screen crew members predicted). But he simply glosses over this and says "within one degree the same". What is what should have happened, but is not what actually happened. This is a very unscientific attitude, and I think this does a tremendous amount of damage to the popularization of science, particularly in the face of accusations that science is just another religion with its own dogmas, high-priesthood, etc. The correct reaction here would have been, "Hm, that's interesting, it started sliding earlier. That's not what I expected, and is not what theory predicts. Let's see if we can figure out why this happened." It's also kind of lame that we have to rely on his callouts to know what angle the board is at. It would have been trivial to set up a pointer that would have been visible to the camera. P.S. Yes, I know that he "explains" the discrepancy at 3:40, but his explanation is bogus. First, the discrepancy is much bigger than the "half a degree" that he explains away. And second, his explanation is actually a hypothesis that is easily tested: just run the experiment multiple times. He could easily have done this and again demonstrated how science is actually supposed to work, but he didn't. P.P.S. He does it again at 7:02 where the longer cylinder is clearly beating the shorter one by nearly a full cylinder radius right before he proclaims "no difference".
  - baddox 9y ago
    I understand your complaint, but this isn’t a formal proof or a research paper seeking peer review. This is an educational demonstration of physics concepts that have already been very well-established through the much more rigorous methodology and peer review you are asking for. Of course the educational demonstration won’t have the same rigor, and it shouldn’t be expected to.
    - sago 9y ago
      With respect, I don't think that was his complaint. The problem is pretending to demonstrate by experiment something that involves abstractions to the real world. It's the same thing with 'demonstrations' that a heavy object will fall at the same speed as a light object where inevitably its 'close enough,' but not actually true (they do in perfect vacuum, but not in a simple experiment). This happens a lot in demonstrating science, because science is really messy. And even relatively simple physical phenomena we don't understand fully (a recent topical example is we don't properly understand why curling stones curl the way they do). The problem is pretending the answer is simpler than it is. Which inevitably leads to motivated 'pseudo-experiments'.
      - lisper 9y ago
        > The problem is pretending to demonstrate by experiment something that involves abstractions to the real world. Not quite. My complaint is pretending that the result of an experiment was something other than what it clearly was and saying, implicitly, "despite the fact that you could plainly see that the result of this experiment was NOT what I said it would be, you should nonetheless believe what I tell you about the laws of physics because I'm the professor and you are the student and I know what's what and you don't. Pay no attention to the actual outcome of the experiment that you saw with your own eyes and instead trust my authoritah." > This happens a lot in demonstrating science, because science is really messy. That's no excuse here IMO. In this case the demo was simply very poorly designed. It's just not that hard to construct a friction and moment-of-inertia demo that actually shows what it is intended to show.

mistermann 9y ago

Tadashi playlist: Tadashi Tokieda: https://www.youtube.com/playlist?list=PLt5AfwLFPxWI9eDSJREzp1wvOJsjt23H_ https://www.youtube.com/playlist?list=PLt5AfwLFPxWI9eDSJREzp...

deleted 9y ago

[deleted]