Why is Lorentz Ether Theory Hard to Rule Out?

[alexandrinushka]

TL;DR Summary

I get that the math is the same for LET (Lorentz Ether Theory) and for traditional SR (Special Relativity). Yet the explanations behind the phenomena aren't, are they? Why high precision lasers cannot rule out LET?

I am reading pretty much everywhere that LET (Lorentz Ether Theory, or call it Neo-Lorentzian Relativity, or whatever theory that involves a preferred undetectable frame with some yet unknown properties that make all the moving objects with respect to this frame length contact and time dilate) and SR are equivalent and that there is no test that can falsify one and not the other.
Although I understand that the math involved is the same, it just seems difficult for me to understand why on an intuitive level.

Here is an example.
We set a high-precision laser with a narrow range. That is to ensure light does not spread all over the place and thus one cannot claim its wavefront has reached everything around.
Several dozens (hundreds?) of meters away we set a large photosensitive paper with a point. The imaginary thread between this target point and the laser opening would be 90° perpendicular to the paper.
Now we fire the laser.
Obviously the laser will hit the paper in that exact perpendicular point. No need for an external observer, the paper would be damaged at the target point.
Two conclusions are possible.
1. SR is right and all inertial frames are equivalent.
2. LET is right and we are by pure coincidence in this special absolute reference frame. But then repeating the experiment several times during the year or even assuming we are not in the preferred frame, but moving at the speed of 368km/s compared to CMB or whatever other hypothetical absolute frame, would quickly rule out this second scenario.
Therefore only the first option is viable and retained. Any movement of the lab setup compared to this absolute frame would necessarily have the laser miss the target point and land somewhere around it, no?
What is wrong with my argument?
This experiment seems so "easy" that I assume I must be missing something essential. I cannot be the first one to have "figured out" such an easy way to rule out LET :D

Thank you in advance for your constructive and instructive support.
Please keep answers at high-school or lower undergrad level.

 

[martinbn]

Why would the laser miss the point?

 

[Ibix]

I think you are mixing up a naive mechanical ether theory, which might have an ether wind to deflect the laser, and LET, which is essentially SR with the added and untestable claim that one frame is somehow special.

As I understand it, experiment after experiment chipped away at the physical properties that an ether could have. Eventually it couldn't have any properties except existence, so it doesn't really add anything to SR even on an interpretative level. That's why it's largely ignored.

 

[alexandrinushka]

Why would the laser miss the point?

It never would in orthodox SR.
In an LET interpretation it would in case of the lab being in movement with a constant velocity with respect to the absolute frame. Well, maybe it's less than a nm amiss, that is not the question. The question is whether with a long enough path and a precise enough laser we can rule out LET.
Why miss the target point? Well imagine we launch the laser. In the meantime the lab, including the photosensitive paper on the other receiver side, are moving. By the time the laser reached the paper, the "target point" is moved already.

 

[Ibix]

In an LET interpretation it would in case of the lab being in movement with a constant velocity with respect to the absolute frame.

No it wouldn't. This is a mechanical ether wind, which is not LET.

In LET the laser is moving in the "real" frame, and so are its lasing medium's electrons and protons and its mirrors. If you analyse a laser with a lateral velocity then you will find that it emits at a slight angle to its axis and the beam hits in the same place as it does when the system is at rest. This is identical to the SR analysis, except for quibbling about calling one frame "real".

 

[alexandrinushka]

I think you are mixing up a naive mechanical ether theory, which might have an ether wind to deflect the laser, and LET, which is essentially SR with the added and untestable claim that one frame is somehow special.

Well that untestable part is quite puzzling for me...
I mean those who support some form of absolute simultaneity (I can only think of Lee Smolin and Sean Gryb for now) must draw a picture in their mind of how light is launched, where it lands and how all of this would correspond to the evidence we have, no?

 

[Ibix]

We've crossed posts. Read #5 if you haven't seen it.

 

[alexandrinushka]

We've crossed posts. Read #5 if you haven't seen it.

Yes, only reading it now, sorry...

 

[alexandrinushka]

No it wouldn't. This is a mechanical ether wind, which is not LET.
In LET the laser is moving in the "real" frame, and so are its electrons and protons and mirrors. If you analyse a laser with a lateral velocity then you will find that it emits at a slight angle to its axis and the beam hits in the same place as it does when the system is at rest. This is identical to the SR analysis, except for quibbling about calling one frame "real".

At a slight angle, hm...
Ok, that kinda makes sense, although I do not understand why it would be emitted at an angle. Length contraction and time dilation cannot justify this. Modern LET says it can do "just as good" as SR with physical LC, clock retardation and absolute simultaneity.
Thanks a lot.

 

[Ibix]

Look up "relativistic aberration". It's a fairly simple consequence of the Lorentz transforms. Conceptually, it's no different to the fact that I, standing still, experience rain falling straight down while you, in a train, see slanted streaks on the window. I say that your train moved horizontally as the drop struck, so the top of the streak got carried along with the window while the rest of the drop was falling. You say the rain is falling at an angle.

 

[alexandrinushka]

Look up "relativistic aberration". It's a fairly simple consequence of the Lorentz transforms. Conceptually, it's no different to the fact that I, standing still, experience rain falling straight down while you, in a train, see slanted streaks on the window. I say that your train moved horizontally as the drop struck, so the top of the streak got carried along with the window while the rest of the drop was falling. You say the rain is falling at an angle.

The raindrop streak helps me visualize it, indeed.
Thank you.

 

[martinbn]

Imagine a ball dropped in a moving train. In the frame in which the train is at rest, the ball hits the floor at a given point, the point right bellow it. Now switch to the frame in which the Earth is at rest and the train is moving. The ball will hit the same point, there is no reason to expect a different result just because of a choice of a frame. Now postulate that the first frame is somehow special, that doesn't change anything, and it doesn't allow you to experimentally test if the frame was indeed special. Given a label to that frame was pointless. LET is just like that, except that it doesn't commit to which frame is special.

 

[Dale]

Why miss the target point? Well imagine we launch the laser. In the meantime the lab, including the photosensitive paper on the other receiver side, are moving. By the time the laser reached the paper, the "target point" is moved already.

An interesting exercise would be to determine quantitatively, according to LET, by exactly how much would it miss the target point. This would be a necessary step for determining how far your laser needed to be and how precise that 90 deg angle needs to be.

Summary:: I get that the math is the same for LET (Lorentz Ether Theory) and for traditional SR (Special Relativity). Yet the explanations behind the phenomena aren't, are they?

Hopefully, it doesn’t surprise you that to quantitatively figure out how far the spot would move you have to use the math. The thing is that the scientific method does not and cannot test explanations. It can only test predictions. And those predictions are made using the math. So if they share the math then they share the predictions and hence are indistinguishable.

 

[alexandrinushka]

Hopefully, it doesn’t surprise you that to quantitatively figure out how far the spot would move you have to use the math. The thing is that the scientific method does not and cannot test explanations. It can only test predictions. And those predictions are made using the math. So if they share the math then they share the predictions and hence are indistinguishable.

Good point.

 

[Sagittarius A-Star]

Maybe, the analysis of the Michelson–Morley experiment helps:
https://en.wikipedia.org/wiki/Michelson–Morley_experiment#Light_path_analysis_and_consequences

 

[PeterDonis]

What is wrong with my argument?

LET and SR make the same predictions for all experimental results; they must, since the math is the same (as you note), and the math is what we use to make the predictions. So any argument that says you can distinguish between LET and SR by experiment must be wrong.

Also, LET is not an allowed topic of discussion on PF. So this thread is closed.