why would it be fabricated? Given some of the opinions he espouses on Twitch and the hardline posture of ICE today it makes sense they'd interview him based on his opinions on Hamas.
There was a deconstruction of his tweets timeline somewhere. He said he was questioned for two hours but the timeline shows the time his plane arrived and then an hour later his tweet that he was out. It leaves more like 20-30 minutes for questioning. There is speculation he actually was pulled aside for a routine Global Entry application on arrival interview since he had said he had applied for it in some prior episode.
This YouTube video is making deconstruction and timeline does not corroborate what Hasan is saying and it also looks like it was standard Global Entry interview
I thought information could only travel as fast as light because that was fastest medium we're currently aware of that can carry information. But that doesn't necessarily preclude other, faster mediums from existing, no?
Not quite. There are two speeds in relativity: the maximum speed and non-maximum speeds (i.e. everything else). It just so happens that light travels at the maximum speed.
Supra-luminal signals will almost necessarily imply that it's possible to violate causality by arranging a series of supra-luminal communications. Not every supra-luminal communication violates causality, but it's hard to think of a way to build a consistent theory that would both preclude causality violations and permit at least some supra-luminal signaling.
Supersonic speed doesn't violate laws of nature or violates casuality. Superluminal speed in matter just produces Cherenkov's radiation.
At superluminal speed, we will be able to hit photons in any order, including reverse order, or emit photons and catch them later. Why this is a problem for casuality?
I know next to nothing about physics, but isn't the "It just so happens" part of what you said potentially misleading? Isn't it that light is massless, so that directly implies that it would travel at the maximum speed?
It's a distinction with no difference. Only massless particles can move at the "maximum speed", in our Universe these are photons and gluons. And maybe gravitons, if they exist.
Similarly, massless particles can't move below the "maximum speed", as they'll have no energy or momentum and won't be able to interact with anything.
Why would the absence of mass force something to travel at the maximum speed? I could understand it being able to travel at that speed; why would it always do so though?
Theoretically, a massless particle can move slower than light. But then it'll have zero energy and momentum, so it won't be able to interact with anything.
No. It's an absolute, inviolable, universal limit on any and all interactions in the universe. It was recently confirmed that even gravitational waves are limited to the speed of light. This (and the Fermi Paradox) are the strongest evidence that faster than light travel or communication of any kind is impossible.
We just call it the "speed of light" because it's the speed that massless particles (like photons) travel at in a vacuum.
Per relativity, any medium that could conceptually facilitate transfer of information or of causality (which are basically the same thing) faster than the speed that light happens to travel at would also be able to reverse direction and arrive at their source in space earlier than the time that they left. That effect is completely unrelated to light itself.
IIRC It’s not that light is a medium. It is that light goes that particular speed max (photons can go slower in fact) because that is the speed of causality.
If this is the lesson where you're introducing pointers to students, you're probably doing them a disservice. Reminds me of my engineering professors who were bored with the material, so they dove straight into difficult problems.
Johnny Harris makes well produced videos that contain a lot of old information and misinformation. If any of his videos cover a topic you're an expert in, you'll see immediately.
No veritasium is pretty legit imo. Johnny Harris is not bad, I’ve heard the same criticism too. I think he won an award in journalistic integrity at one point.
Theres no YouTuber without criticism. Referring to no one in particular: There’s even offensive snobbish garbage comments equivalent to the banality of Mr. Beast videos here on HN yet this doesn’t reflect the overall vibe here.
Don’t try to bring my overall point down by attacking one particular aspect of one particular example. What should the snobbery of some of the commentary on HN here render the entire site moot? No. My point stands regardless.
> Don’t try to bring my overall point down by attacking one particular aspect of one particular example. What should the snobbery of some of the commentary on HN here render the entire site moot? No. My point stands regardless.
No, you giving two for two garbage suggestions shows how easy it can be for garbage content to masquerade as good. Both on YouTube, in HN comments, and elsewhere.
it's not true of veritasium; he is meticulous about correctness. it's true that his videos do include a lot of old information, but it's correct old information such as the theory of relativity
agreed. This one: https://www.youtube.com/watch?v=oI_X2cMHNe0 generated a lot of controversy and he ended up being right. Hence the criticism. It's almost like the Monty Hall problem for Marilyn vos savant where even people with PhDs derided her for being wrong when in fact they were all wrong themselves.
well, the truth turned out to be quite complicated; see also https://www.youtube.com/watch?v=2Vrhk5OjBP8 and https://www.youtube.com/watch?v=2AXv49dDQJw. the result is more complicated than just a single time delay, and the details of the experimental setup (like the wire diameter! and load impedance relative to transmission-line pulse impedance) matter a lot. in alphaphoenix's first experiment, putting 5 volts into a kilometer of wire, he got 0.2 volts across his resistor immediately, then after about 1.6μs, a jump up to about 2 volts, and then a gradual rise to 1.7 volts, some overshoot peaking after another 1.6μs, and then settling back down to the 1.7-volt level
(derek's results in the linked video, which incidentally links to one of the two i linked above, were quantitatively different but qualitatively similar)
the really unintuitive thing about this i think is that people think of electrical energy as flowing inside wires, when actually almost all of it flows around the wires, as veritasium explained quite ably. this is something people doing high-speed pcb layout have to deal with a lot in order to avoid emi problems
as i understand it, derek has a ph.d. in physics, or actually in physics education researchhttps://youtube.fandom.com/wiki/Veritasium. that doesn't mean he knows everything about physics, but generally my experience with people in ph.d. programs is that they're good at listening to counterarguments and admitting when they're wrong, and also seeking out experts before publishing
(i think the veritasium video does contain a minor error in that it says electrons collide with metal ions, which as i understand it is not exactly how ohmic resistance works—the 'electrons' moving through the lattice are not exactly electrons but virtual particles similar to phonons or plasmons, and so the things they scatter off of are not individual ions—but possibly derek knows this and was intentionally simplifying, or possibly my understanding is wrong. i mean, i don't have a ph.d. in anything, much less solid-state quantum physics! derek certainly knows the electrons traveling through the wire aren't point-like particles bouncing around like billiard balls, and that the ions aren't red spheres with plus signs on them, despite depicting them that way.)
>i think the veritasium video does contain a minor error in that it says electrons collide with metal ions, which as i understand it is not exactly how ohmic resistance works—the 'electrons' moving through the lattice are not exactly electrons but virtual particles similar to phonons or plasmons,
electrons are moving through the wire. The virtual particle thing is a misunderstanding on your part I think.
I think your talking about current. Current flows in the opposite direction of electron drift velocity. In the simplified model they use these things called negative and positive charges flowing through the wire and current is defined as the movement of positive charge. These "charges" are of course virtual in nature because it's not what's actually happens.
What actually happens is negative charge is moving and positive charge (protons) are frozen.
And yes of course derek knows that it's a wave traveling through the lattice.
while of course that is correct, that's not what i'm talking about
there is a good introductory presentation in https://www.feynmanlectures.caltech.edu/III_13.html but note that it assumes some previous familiarity with quantum mechanics. §13.6 explains that mostly what the electrons (really propagating waves of quantum probability amplitude for there to be an extra electron) are scattering off of is imperfections in the lattice. but that can't be the whole story or all perfect crystals would be superconductors
I made a hearing aid app for the iPhone nearly 10 years ago. It was nearly impossible to get anybody to pay $10 or less for it.Also, there is/was a FDA exception for mobile apps, which kind of obviated the need for the grad school class i was taking at Stanford about getting medical devices FDA approved.
