No one’s saying that forces “just build up” by virtue of applying for a long time. Azathoth123 is saying that in this particular case, when these particular forces act for a long time they produce a gradually accumulating change (the rotation of the ring) and that as that change increases, so do its consequences.
Your rope is moving faster and faster, whether or not it goes all the way around the galaxy. The relations between different bits of the rope are pretty much exactly the setup for Bell’s spaceship paradox.
Yeah, but it’s a “paradox” only in the sense of being confusing and counterintuitive, not in the sense of having any actual inconsistency in it. The point is that this is a situation that’s already been analysed, and your analysis of it is wrong.
It wouldn’t be a problem, if it was just “paradox”, but unfortunately it’s real.
We can’t and therefore don’t measure the postulated Lorentz contraction. We have measured the relativistic time and mass dilatation or increase, we did. But there is NO experiment confirming the contraction of length.
To get direct verification of length contraction we’d need to take something big enough to measure and accelerate it to a substantial fraction of the speed of light. Taking the fact that we don’t have such direct verification as a problem with relativity is exactly like the creationist ploy of claiming that failure to (say) repeat the transition from water-dwelling to land-dwelling life in a lab is a problem with evolutionary biology.
We have. The packet of protons inside LHC, Geneva.
Packets all around the circular tube. Nobody says, they shrink. They say those packets don’t qualify for the contraction as they are “not rigid in Born’s sens” and therefore not shrinking.
If we can measure even a tinny mass gain, we could measure a tinny contraction.
If you read the whole article instead of quote-mining it for damning-looking sentences, you will see that that’s incorrect.
They modelled, performed experiments, and compared the results. That’s how science works. The fact that the article also mentions what happens in the models beyond the experimentally-accessible regime doesn’t change that.
Every rigid body is just a cloud of particles. If they are bonded together, they are bonded together with other particles like photons. Or gravity. Or strong nuclear force, as quarks in protons and neutrons.
Also the strong nuclear force is responsible for bounding atomic nucleus together. The force just doesn’t stop at the “edge of a proton”.
But why do you think they “must be bonded together” in the first place?
Hubble flow is at best a very noncentral example of travelling. Also, images aren’t supposed to show any contraction (see Terrell rotation), only the objects themselves.
(Why are you expecting apparent sizes to match real sizes in the first place? The Sun looks as small as the Moon as seen from Earth, do you think it actually is?)
Of all light rays entering your eye right now, the ones coming from parts of the object farther away from you departed earlier than the ones coming from parts closer to you. If the object moved between those two times, its image will be deformed in a way that, when combined with Lorentz contraction, foreshortening, etc., will make the object look the same size as if it was stationary but rotated. This is known as Terrell rotation and there are animated illustrations of it on the Web.
(BTW, galaxies are moving along the line of sight, so their Lorentz contraction would be along the line of sight too, and how would you expect to tell (say) a sphere from an oblate spheroid seen flat face-first?)
I agree that “Lorentz contraction” is a misleading name; it’s just a geometrical effect akin to the fact that a slab is thicker if you transverse it at an angle than if you transverse it perpendicularly.
No one’s saying that forces “just build up” by virtue of applying for a long time. Azathoth123 is saying that in this particular case, when these particular forces act for a long time they produce a gradually accumulating change (the rotation of the ring) and that as that change increases, so do its consequences.
I understand. But imagine, that only 1 m of rope is accelerated this way. No “forces buildup” will happen.
As will not happen if we have rope around the galaxy.
Your rope is moving faster and faster, whether or not it goes all the way around the galaxy. The relations between different bits of the rope are pretty much exactly the setup for Bell’s spaceship paradox.
And? The Relativity isn’t coherent, that’s the whole point.
Transition from one, to another paradox doesn’t save the day.
Yeah, but it’s a “paradox” only in the sense of being confusing and counterintuitive, not in the sense of having any actual inconsistency in it. The point is that this is a situation that’s already been analysed, and your analysis of it is wrong.
It wouldn’t be a problem, if it was just “paradox”, but unfortunately it’s real.
We can’t and therefore don’t measure the postulated Lorentz contraction. We have measured the relativistic time and mass dilatation or increase, we did. But there is NO experiment confirming the contraction of length.
To get direct verification of length contraction we’d need to take something big enough to measure and accelerate it to a substantial fraction of the speed of light. Taking the fact that we don’t have such direct verification as a problem with relativity is exactly like the creationist ploy of claiming that failure to (say) repeat the transition from water-dwelling to land-dwelling life in a lab is a problem with evolutionary biology.
We have. The packet of protons inside LHC, Geneva.
Packets all around the circular tube. Nobody says, they shrink. They say those packets don’t qualify for the contraction as they are “not rigid in Born’s sens” and therefore not shrinking.
If we can measure even a tinny mass gain, we could measure a tinny contraction.
Had there been any.
Funny you should mention that.
See? It’s only calculation based on Relativity, not actual experimental data.
If you read the whole article instead of quote-mining it for damning-looking sentences, you will see that that’s incorrect.
They modelled, performed experiments, and compared the results. That’s how science works. The fact that the article also mentions what happens in the models beyond the experimentally-accessible regime doesn’t change that.
A bunch of particles not bound to each other by anything is not rigid in any reasonable sense I can think of, so what’s your point?
Every rigid body is just a cloud of particles. If they are bonded together, they are bonded together with other particles like photons. Or gravity. Or strong nuclear force, as quarks in protons and neutrons.
Also the strong nuclear force is responsible for bounding atomic nucleus together. The force just doesn’t stop at the “edge of a proton”.
But why do you think they “must be bonded together” in the first place?
https://en.wikipedia.org/wiki/Length_contraction#Experimental_verifications
The link you gave does not talk about the direct observation of the Lorentz contraction. Rather of “explanations”.
Fast traveling galaxies, of which all the sky is full, DO NOT show any contraction. That would qualify as a direct observation.
Hubble flow is at best a very noncentral example of travelling. Also, images aren’t supposed to show any contraction (see Terrell rotation), only the objects themselves.
If images aren’t supposed to show any contraction, then measurements aren’t supposed to detect any contraction.
My point exactly.
Are you saying, that there in an invisible contraction?
(Why are you expecting apparent sizes to match real sizes in the first place? The Sun looks as small as the Moon as seen from Earth, do you think it actually is?)
Of all light rays entering your eye right now, the ones coming from parts of the object farther away from you departed earlier than the ones coming from parts closer to you. If the object moved between those two times, its image will be deformed in a way that, when combined with Lorentz contraction, foreshortening, etc., will make the object look the same size as if it was stationary but rotated. This is known as Terrell rotation and there are animated illustrations of it on the Web.
(BTW, galaxies are moving along the line of sight, so their Lorentz contraction would be along the line of sight too, and how would you expect to tell (say) a sphere from an oblate spheroid seen flat face-first?)
I agree that “Lorentz contraction” is a misleading name; it’s just a geometrical effect akin to the fact that a slab is thicker if you transverse it at an angle than if you transverse it perpendicularly.
Yes. Rotated rope looks shorter. Problem remains.
We see the close and the far edge of many of them. Still, the pancake apparently isn’t neither squeezed neither rotated.
What problem?