[1]https://www.youtube.com/watch?v=fQQ8IiTWHhg [2]https://www.youtube.com/channel/UCoxcjq-8xIDTYp3uz647V5A [3]https://www.youtube.com/channel/UCSD2RxaYn2Nxkm41gp-eKfA
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".
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'.
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.
Consider this from the perspective of someone who knows nothing of physics and is skeptical of science and academia. Here is a person that shows us he is wrong, does almost nothing to rectify this (there is a very brief explanation, but why not more demonstrations? Or really, why not just prepare a better demonstration that doesn't have these problems?), and then continues to pontificate as an authority figure.
If his goal is to offer a refresher to people that already know the physics, okay I guess this makes sense, but I sure as hell would've liked a refresher on the equations personally (so I am not the target demographic). If his goal is to teach people that know nothing of physics, he really could've done a lot more to actually teach and explain things.
Getting back to my first paragraph though, I feel like this comment thread might be a great example of humans being humans - everybody is susceptible to confirmation bias (again I could be wrong, but that hypothesis makes the most sense to me). If you didn't already understand the physics and you didn't take him at his word because he is a college professor, honestly his tutorial is unconvincing. He completely ignores the scientific method!
He gets away with it because he doesn't need to convince his fellow scientists, only a bunch of pupils. But it is nevertheless quite unscientific.
So some lecturer might think of themselves as demonstrating only friction. But they're also demonstrating how to present material, how to do lab safety, and perhaps also how to silently subordinate observation and data to expectation and narrative.
When doing a demo, one can easily acknowledge and flag a divergence with a "<expectation>... more or less".
And it's not just a problem for students. In the context of science education research, a first-rate stone-cold-empircial experimental physicist, when thinking about their teaching, might be "like, I have gut feel for what works - I trust my gut". Sigh. I know a biologist, who does respected work, but get them started on <other thing that's not their research focus>, and it's a bizarre sidestep into earthy-crunchy crystal-crazy land. Pity the poor student trying to figure out which of all these are the behaviors to emulate, and which not.
I wanted to continue watching the video because I should watch the whole thing if I'm gonna criticise it.
But then he lied about the stapler. Just because he skipped counting "15, 16, 18, 19.." doesn't mean it didn't start sliding at 17 degrees, which is in fact within one degree of the unweighted yellow box (if you take his word for it, or within two degrees if you go by what you saw), either way definitely closer than when the weighted yellow box started sliding.
If there's one thing this video tells me it's that the angles that he measures are accurate to no more than +/- 5 degrees. Therefore drawing conclusions about differences that are less than that is FLAWED.
What he is demonstrating is how NOT to do a physics experiment.
It's terrible!
If he just wanted the audience to take away from this video that friction is independent of weight or whatever, it would have been better if he had just told the story in front of a blackboard or something.
I stopped watching when he claimed the two cylinders of different length made "no difference". https://i.imgur.com/SXg4FRk.png FFS this is just embarassing.
It's pretty obvious that this guy is just going through the motions telling a rehearsed story that has not much to do with the actual outcomes of the "experiment" he is trying to make us believe he is performing.
If you think that's okay, then imagine replacing this "demonstration" with an animated cartoon of the very same. How convincing would that be to you? Because he does say "you just gotta take my word for it", a lot.
> this isn’t a formal proof or a research paper seeking peer review
No but it is a youtube video of a physics experiment. They don't get peer reviewed. What is it exactly that you are trying to say?
Am I not allowed to expect some amount of rigour and honesty unless it's a research paper seeking peer review?
If it intends to be educational, at least don't show that apparently it's okay to fudge results in a physics experiment as long as you're a MIT professor and say "just take my word for it". Because that's my takeaway from this video: "this guy probably shouldn't do physics experiments".
Because most Youtube videos on scientific topics I've seen, they either perform the experiment correctly, but if they don't get the results that they "should", they own up to it. Sometimes they record the experiment again, and they TELL you it failed at first and what they changed. Sometimes I even hear them lament that they filmed a great experiment, got the results they wanted, but had to trash the video because it just looked fake and unconvincing (because of the angle, timing, just didn't work on camera, etc)[0].
It sucks for their time and effort but they know they can't use it because it would completely undermine their point when the comments point out how fake it looks.
Guess who disabled commenting on their video? You're absolutely right about not seeking peer review, or in fact any review.
Quick check of some other vids on that Physics World youtube-channel, in particular a few videos with a professor or PHD talking or doing an experiment: NONE (of the ones I clicked so far) had their comments disabled!
So what I'm guessing happened here is, a LOT of people had issues with the fudging of the experimental results and dis-ingenuity of what they supposedly demonstrate. They commented and pointed out that what the man says is happening isn't actually what they see is happening, and that makes it really hard to "just take his word for it".
I doubt it even got really ugly before someone's ego got a dent in it and instead of deleting the crummy video, they took the much easier road of deleting the criticism.
If he's doing this all the time in Skype demonstrations all over the world, why put up a video where the first couple of experiments clearly don't show what he's saying they show?
[0] That example btw, was Tom Scott a couple of times, huge respect. Not only owning up to failed experiments, but clearly talking about the experiments he DID do, that DID NOT work out as he hoped, so much that he didn't want to publish them (on YouTube), but he still said he did the experiment. That's a HIGHER STANDARD actually than a proper scientific formal proof or peer-reviewed research paper is held to!!!! Peer review doesn't check for publication bias.
I have no clear conclusion for how this relates to your point though. Maybe modern education should include this as abc basics, not as high school revelations. Uneducated people are hard to convince, since they don’t know that reality is hard, while beliefs are easy.