Need opinions on Youtube video: "From constant moving charge to SR"

[TCO]

TL;DR

Youtube video: "How Superposition Causes Length Contraction -- And Explains the Principle of Relativity"

Im utterly confused about this video and I would like some opinions about it:

"How Superposition Causes Length Contraction -- And Explains the Principle of Relativity"


Approximately content:
1) Length contraction is entirely physical (shorter molecular bonds??).
2) Oliver Heaviside's retarded potential.
3) He is introducing some wave mechanics(Maxwell?) for electric force/potentials propagation.
4) Choosing to work with the retarded scalar potential.
5) This potential updates its value via. waves (what type of wave?)
6) Calculating the retarded potential in front(weaker) of the moving charge and after(stronger). (@12:29min)
7) Introducing superposition of wavefronts: "Our charge is continuously emitting wavefronts." (potential "waves"?)
8) Adding the two contributions: retarded potential + "wavefront superposition"
9) Using Doppler effect formula for waves in a medium (like sound waves, not the relativistic Doppler effect formula).
10) Cancel terms.
11) Recover The Principle of Relativity.
12) Calculates the potential in the y-direction.
13) Recovers pancake potential.
14) Calculate vector potential.
15) Recover formulas for electric and magnetic field.

I think (somewhere, Doppler effect?), he assumes that light speed is not constant for all observers.
But also, what is this "wave mechanics" for potentials?

Is he inventing his own (wrong) "physics" to get rid of relativity?

 

[Nugatory]

If your summary of this video is accurate then your skepticism is justified.

The a priori probability that an internet video (making an extraordinary claim in the title) will be bogus is so high that not many people who are qualified to check your summary for accuracy will be willing to spend 23 minutes watching it, but we will leave this thread open just in case.

Generally it's less work and more effective to seek out reliable sources than to sift through the unreliable ones looking for something valuable.

 

[phinds]

1) Length contraction is entirely physical (shorter molecular bonds??).

That's such nonsense that I have zero interest in reading any further. Forget pop-sci presentations and read some actual physics.

 

[TCO]

Thanks.

I suspected it was nonsense, but I was confused by the lack of critical comments and the many views.

I have many physics books as I studied physics 20+ years ago and I had to open four of them again to debunk this video...

What a sad state of Youtube physics information...

 

[Ibix]

I suppose it's possible the video is doing something like Lorentz Ether Theory, which is an alternative interpretation of relativity with a privileged frame. It's kind of the rump of mechanical ether theory once experiment chips away at the mechanical properties the medium can have until there's nothing left. You can either say it doesn't exist (vanilla SR) or say that it exists but is undetectable (LET). Literally all the Lorentz ether does is privilege one frame's measurements as accurate descriptions of reality, so all other frames' measurements are less correct in some sense. But which frame is "real" remains undetectable, so it's a pointless addition to the theory that everybody drops.

However, once you privilege a frame like that you can take its measurements of velocity difference as the "real" relative velocity between two things, so light speed relative to you is "really" $c-v$, and you only measure it to be $c$ because your measurements are messed up because your instruments are moving relative to the privileged frame. Since the priviledged frame is indistinguishable from any other, though, this is all just unnecessary complication compared to the standard interpretation.

 

[TCO]

Yes, he(the channel) likes ether, maybe that's why he uses the Doppler effect for waves in a medium...the goal of the channel seems to be to recover some intuitive archaic version of "classical reality"...

- like here:

 

[Ibix]

In that case I'd just ignore. The world is as complicated as it is. You can, to some extent, recover simpler views on it by brushing stuff under the mathematical carpet ("relativistic mass" is one of the more famous examples of trying this in mainstream physics), but eventually somebody asks about that huge bump under the carpet and it all comes out.

We handle a lot of confused questions here from people who've poked the bumps of pop-sci, so we're big advocates of being upfront about the world not being quite what an intuitive mental model might suggest.

 

[PeroK]

Yes, he(the channel) likes ether, maybe that's why he uses the Doppler effect for waves in a medium...the goal of the channel seems to be to recover some intuitive archaic version of "classical reality"...

- like here:

I would urge some caution here. It's becoming painfully clear that the mass of misinformation on the Internet generally leads to a much greater likelihood of people accepting fringe, conspiracy or crackpot theories. Almost everyone I know has friends who buy into this stuff. One of the key points is to make you think that mainstream = gullibility; and, crackpot = being skeptical and thinking for yourself. Whereas, of course, it's essentially the other way round. Once someone has bought into a conspiracy theory, they believe everything the conspiracists say without question.

This stuff is like a drug and by consuming it you run the risk of becoming addicted. Be careful they don't suck you in.

 

[Ibix]

- like here:

I didn't see the video link earlier. I presume it's a reaction video to the Sabine Hossenfelder video in the thumbnail, which it has to be said is terrible. It falls smack into the "acceleration causes time dilation" trap and generalises it to gravitational time dilation, getting everything wrong. We've discussed it a couple of times and Kevin Brown made some comments on it that we discussed here.

 

[pervect]

TL;DR Summary: Youtube video: "How Superposition Causes Length Contraction -- And Explains the Principle of Relativity"

I watched until I found something that was ill-thought out, which starts with his observation about field lines. There's nothing surprising about the field lines of a charge in uniform motion that never accelerates or deaccelrating not changing. If the charge accelerates briefly to change it's motion from "at rest" to moving, there is indeed a "kink" in the field lines that is delayed, as one would expect. MTW has a diagram of this, google finds this diagram reposted on stack exchange https://physics.stackexchange.com/questions/70054/why-do-accelerating-electrons-emit-radiation

The relevant image is:

If I had more patience I might continue to watch the video - but I didn't.

Back to the point I was making - doing a transform to change from a "stationary" frame of reference to a "moving" frame of reference is just a relabeling of coordinates, creating a different view of the same physics. -There is nothing about this process that propagates. You can change your mental image as fast as you like. Physically changing the state of motion of a charge by accelerating it does cause propagation effects.

 

[A.T.]

I didn't see the video link earlier. I presume it's a reaction video to the Sabine Hossenfelder video in the thumbnail, which it has to be said is terrible. It falls smack into the "acceleration causes time dilation" trap and generalises it to gravitational time dilation, getting everything wrong. We've discussed it a couple of times and Kevin Brown made some comments on it that we discussed here.

Unfortunately, the reaction video, just like Sabine's video, fails to distinguish between accelerated frames and accelerated clocks. Merely talking about "acceleration causing / not causing something ..." is always the root of the confusion that follows.

My previous comment on Sabine's video:
The confusion starts when accelerating reference frames (which can have clocks going at different rates at different locations) are conflated with the proper acceleration of the clocks (which doesn't affect the clock rate).

Context:
https://www.physicsforums.com/threa...n-is-due-to-acceleration.1051866/post-6877595