That's what they tell us. Light can travel through a vacuum with nothing in it. And maybe so but what is the evidence?
So I looked up the best vacuum on planet Earth. It contains 2.5 million molecules of air per cubic cm. This is said to replicate conditions between stars. So how then can we say we've ever tested light waves going through "nothing". We haven't.
To test the validity of my suspicions I've asked the science guys on reddit if they have an answer for this. The first few responses have already been hostile and that usually indicates this is one of those issues they simply don't have a good answer for. I was very polite in my question btw, so no I didn't provoke anybody, this is all on them.
We'll see how it goes. I'm open to a good explanation of why this is a valid test, but this light has 2 million molecules to interact with ever cubic cm it propagates, so you didn't rule out matter.
The difference being one is moving with the medium, the other perpendicular to it. So we would expect different results. For Sagnac (including those showing linear motion, not only rotation) we see a fringe. That includes when the detector is NOT in rotation (some have tried to argue that this is the causal mechanism, but it is not). Therefore when the air is moving perpendicular to the light and with the detector as in the MMX aparatus, we would expect a null result.
I appreciate the recommendation, I will look into it.
In the mmx - ideally anyhow - the medium is stationary (in the local frame of reference).
The fringe occurs because of motion. The fringe that didn't appear in the mmx (or rather, didn't appear outside the range of error / vibration for the device) is the measurement of that lack of motion.
The sagnac i am familiar with is basically on a spinning kitchen dolly. When stationary - a circular/curved path - would be expected to exhibit a minor fringe pattern for the same reasons the circular gale pearson (also stationary) did.
It's the motion of the detector that is registered though, not the air. All the rlg's lasers go through fiber optic cable which surely doesn't have much gas within it nor would moving air affect its measurement (except, notably - through vibration).
They also rotated the apparatus many times to try and determine the "true" direction of motion of the earth around the sun. This ought to have dealt with that "perpendicular blindness issue" - right?
Please let me know your thoughts on it, and/or if you have trouble finding it. I've recommended it to others a few times too but haven't seen it in years. I think i ought to rewatch it myself and see if i still think as highly of it now as i did back then.
Exactly, if the air is "stationary" in the local reference frame it is moving along with a rotating Earth. So detecting any effects of rotation would not be possible with mmx if Sagnac is invoked.
You're missing what I'm saying. It is motion either way, but in one case the motion is the exact same as the rotating Earth. So of course there can not be a fringe if the air is moving the wave over.
But it turns out it has nothing to do with being circular. That's already been shown in better experiments.
I have no reason to think that. The detector is hit after the beams have recombined. So any changes in the velocity was done before reaching it.
Not so. I suppose it's more than* an issue of perpendicular vs not. With MMX the beam travels half the journey one way then half the other, so all the effects in the direction of movement are cancelled out. MMX just assumed the perpendicular effects are not cancelled out, but in fact they also are (at least in air).
The only way to see the effects is with a device that only pushes the light in one direction before it recombines with the split portion of itself. See this aparatus which did just that... https://media.scored.co/post/3fvtgZNPCd1F.png
But that is precisely what the gale-pearson (and every rlg, routinely) detected!
Very possibly.
I don't think i understand what you mean by this. How do you think air is causing a fringe pattern in a stationary rlg (in a room with no wind)?
But this is the core difference between mmx (detected no cosmic linear motion) and gale pearson (detected local/earthbound rotational motion)
But even if the mmx was "perpendicular blind", in a right angle configuration - one of the legs would be parallel with the motion and one perpendicular - creating the fringe pattern...
That is certainly an interesting apparatus. However if that loop is intended to spin on the spindles that is certainly going to introduce vibration (and hence fringe) in and of itself... What is the device intended to observe?
I mean the air is moving the wave over at the same speed of Earth's rotation then. So how could there be a noticably difference between a rotating Earth with rotating lower atmosphere and no rotation measured with this? There can't be.
I don't know gale pearson yet. But from what I understand MMX was designed to look at earthbound rotational motion as well.
Yes it is intended to be mover on those wheels or spindles. Not sure how much vabration was in the system, ask Mr Wang who made it.
The device is intended to observe Sagnac and look at how much linear motion contributes to the effect over a standard rotational only setup.
If the device I cited looks odd I would first study the mechanisms behind a fiber optic gyroscrope. It splits a beam of light, those light beams take different paths around the circle in opposite directions, they then recombine.
Although, I do see the possible objection for the detector moving. They have it moving linearly with the same velocity as the fiber optic cable it is measureing.
So I think it is the parallelogram experiment that actually rules out the detector motion. The base is stationary. https://media.scored.co/post/7NYfywPD4Z1R.png
I think i have a pretty good grasp on the rlg and interferometery in general. That said, the device still looks a little odd to me. Are the arrows showing the fiberoptic cable moving or is that just the direction of the light?
Just like a standard rlg.
So they are moving the cable? Wild, if so.
Again, i may be confused about what you are saying. Unless i am very much misunderstanding the diagram - the device will ONLY show interference pattern when the device is moving (and air is irrelevant). Right?
The fiber optic cable is in fact moving.
Only the top part of the paralellogram moves from right to left. The base is stable.