Is it true? Is the universe flat?

Are you actually taking a position on anything? Trying to catch AlphaNumeric in a contradiction is not a position. The only assertions I've seen you make in this thread are that Sagnac occurs without acceleration (false) and that MMX+Sagnac, taken together, are contradictory (false).

 

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No, I think that is an issue with your reading comprehension and nothing more.

The posts show clearly I was explaining to AlphaNumeric his position that being at rest with CMB is no different from being at rest wrt to anything else is a contradiction and provided the clear evidence to show that.

Now, if you are able to take that position of AlphaNumeric, then have at it. I will correct you as well.

 

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The problem with getting involved with you is that I have little faith that you will address all points made if they are inconvenient to you, but I guess I'll try...

I don't know what AN originally said, but this talk of being at rest with respect to (from now on: wrt) photons is not possible, first of all; we can only talk of being at rest wrt to the photon source. Making the local CMB isotropic is as close to being at rest wrt the Universe as you can be. Actually being completely at rest wrt the entire Universe is not possible since the expansion means it is accelerating in all directions, and remaining inertial with multiple accelerating sources is not possible. I suppose one could say that the "ideally inertial frame" would be at the universal center of mass (presuming it exists) while also minimizing CMB in all directions.

All that being said, your counter-argument is wrong. Please provide an example of an "earth based application where the light source and receiver are at rest in ECEF yet conclude the earth's rotational sagnac." It does not exist.

 

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You played back my argument. It is written in this thread.

I introduced MMX to force him into a differential from SR relative to his argument in which I intended to run him into a contradiction. The proof of this is in the thread.

So,I am glad to see you adopted my argument after that. That means you are a follower of mine. I guess.

Find another master.

 

In an intercontinental microwave link between Japan and USA via a geostationary satellite as relay, the influence of the Earth’s rotation is also demonstrated in a high-precision time comparison between the atomic clocks at two remote stations [9]. In this transpacific-link experiment, a synchronization error as large as about 0.3 μs was observed unexpectedly and then is attributed to the Sagnac effect due to the Earth’s rotation after a detailed analysis.
http://qem.ee.nthu.edu.tw/f1b.pdf

 

I see. So your contention is that the 3 components (the equipment in USA, Japan, and the Geo-stationary satellite) are at rest?

 

Yes that would be my contention.

But, let this be your guide.

The Sagnac Experiment

Sagnac constructed a ring interferometer and measured its fringe shifts as it is rotated. Contrary to some uninformed claims, this experiment can be fully analyzed using SR, and the results are consistent with SR.

Sagnac, C.R.A.S 157 (1913), p708, p1410; J. Phys. Radium, 5th Ser. 4 (1914), pg 177.
The classic papers by Sagnac.

Post, “Sagnac Effect”, Rev. Mod. Phys., 39 no. 2, pg 475 (1967).
A review article. This is probably the most useful reference on ring interferometers and the Sagnac effect.

Anderson et al., Am. J. Phys. 62 no. 11 (1994), pg 975.
A more recent review, and description of a much more accurate ring interferometer.

Hasselbach and Nicklaus, Phys. Rev. A 48 no. 1 (1993), pg 143.
The Sagnac effect using electrons.

Allan et al., Science, 228 (1985), pg 69.
They observed the Sagnac effect using GPS satellite signals observed simultaneously at multiple locations around the world. See GPS.

http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html

 

You might have noticed that I'm not actually taking a position here. I'm just pointing out that you don't seem to grasp the difference between special and general relativity, between minkowski spacetime and curved spacetime.

I don't pretend to have an expert grasp on those things myself, so I recommend you read further.

It's called 'homework'.

 

So, in your understanding of Physics, rotating systems are at rest? Giving me references to Sagnac effects is not going to help this assertion. Sagnac only occurs in rotating systems, and rotating systems are under acceleration. Systems under acceleration, by definition, are not inertial nor at rest, period. Please tell me how many times something must be told to you before you learn it.

 

Changing frame is an 'instantaneous' thing. This means that at a given instance applying the SR Lorentz transform to change frame doesn't have to deal with any general relativistic effects. The temperature of the sky can be used to determine a particular frame, that where the CMB has no dipole, but setting yourself to be in that frame doesn't give any physics different from putting yourself in any other frame. The CMB is just a physical construct which allows a particular frame to be referenced, just like the Earth or Sun are physical objects which have particular (instantaneous) rest frames. That deals with a specific point in space at a specific time.

My explanation to Farsight as to why the CMB, despite being everywhere, is not a universal absolute reference frame was due to it being a general relativistic effect and people at different points in space or the same person at the same point but at different times will be able to observe things which special relativity cannot explain, as the effect is due to the length scale associated to the expansion.

How many times more am I going to have to explain this to you? If you actually know some relativity I'd not have to be doing this. For instance, my comments about SR choices of frame at a specific point at a specific time should be understandable if you are familiar with normal coordinates. A choice of coordinates at an instant can have \(g_{ab} \to \eta_{ab}\) and then you have residual Lorentz invariance coordinate freedoms. But this only works for an instant, if two observers are separated in space or time then they'll be able to detect GR related phenomena, no matter what coordinates they use.

Either you're deluded in how much relativity you think you understand or you're just trolling. You've done this in other threads, so much so that James R has stopped responding to you because you won't even answer direct yes or no questions. If you can't do that then you're showing you're dishonest and you know it. All you're doing with me is saying "Nuh uh! That's wrong!" and then ignoring when I explain myself, bringing up points I've already addressed. If you can't enter into a discussion go troll somewhere else.

 

Thanks, but I have demonstrated AN does not understand the difference between the GR and SR based on his statements.

Now, why don't you prove his statements are consistent.

 

Perhaps you can explain why GPS shows a sagnac when the amount of rotation in .05s can't influence the results. If you check here
http://www.mathpages.com/rr/s2-07/2-07.htm

you will see path length is the only issue.

Check here, you will also find path length is the only issue.
http://relativity.livingreviews.org/Articles/lrr-2003-1/


Further, here is a mainstream paper for linear sagnac.

http://web.stcloudstate.edu/ruwang/PRL93.pdf

So, you have much to learn. See you later.

 

The letters after my name would beg to differ.

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If you have anything other than assertion please provide it. If I perhaps hadn't explained my thoughts enough initially I've certainly clarified them since, multiple times. You haven't engaged in a discussion, you have ignored all attempts to discuss it and you just repeat comments already retorted. This is just how you tried to talk with James R. In that case you eventually couldn't even answer direct yes or no questions, illustrating you know your actions are dishonest.

I explained why they are not inconsistent, you haven't responded to what I said. You ask Pete, ignoring that I've already done so and that you failed to respond. That is typical crank behaviour, asking people to provide responses which have already been provided and which you've ignored. If you're unwilling to discuss things honestly you're trolling.

 

This is bunk.

You still not have addressed this. You need to learn to admit when you have failed.

Here is my post

Now either prove my clear statements false, or accept you are wrong and have failed.

But, I can see you intended "at rest with photons" to mean a specific point in time for the entire universe.

If you can make the entire universe at rest, then your statements are true. Is that it AN?

Why not simply admit you are failed and are wrong?

 

A difficult lesson to learn. I find that many students don't learn it until postgrad studies.

 

FOR F&CK SAKE, how can the path length be changing if you maintain that the emitter, relay station in space, and the bloomin receiver are all at rest wrt each other? (FYI, they aren't at rest, but their relative distances are not changing) Sagnac is the ONLY thing that explain this. Where exactly did you get the ".05s can't influence the results" comment? Did you pull it out of your ass where you apparently store the rest of your knowledge?

The links you're giving me show nothing unexpected. Turn on a light equidistant from two mirrors, then move the source towards one of the mirrors and...surprise! That reflection is seen first. Sagnac is neither demonstrated nor needed when discussing changing path lengths between emitter and receiver. How you believe that it isn't Sagnac that causes the GPS errors, even though the distances between the stations DOES NOT CHANGE I'll never know. What you're suggesting is exactly what Motor Daddy talks about - absolute motion relative to the f&cking aether, and unfortunately you're starting to sound less like a troll and more like a general goofball.

 

I have, repeatedly. You haven't addressed any of my responses. I'll reply one more time, after that I'll do as JamesR did and simply regard you as a troll because you clearly have no wish (and likely no ability) to engage in honest discussion.

The comment about setting ones motion wrt to lots of photons was poorly worded, I admit, but I've clarified it. I was referring to using the aggregate behaviour of the CMB to determine a dipole in the temperature of the sky and to set your motion at a particular location to be such that you observe no dipole. This is just a Lorentz transformation, because it acts at a single point at a single moment in time. My comment about it being no different to setting your frame to any other frame was in reference to the fact the CMB is an 'object' like any other and setting your motion in reference to it is no different to setting your motion in reference to anything else, contrary to Farsight's claim it was somehow 'absolute'. I then went on to explain how its not absolute in a more general relativistic sense either, in that people doing as I just outlined at different points in space will find themselves moving relative to one another due to space-time expansion, which a GR, not an SR, effect.

Where does any of that involve me specifying a point in time for the entire universe? Where do I need to make the entire universe at rest? You claim that's what my explanation requires, prove it. Failure to do so will result in you simply being regarded as a troll. RJBeery has reached the same conclusion as James R and myself. You're failing to convince anyone of anything but your ignorance.

And don't think I didn't notice you just ignored my comment about how I do understand this stuff. You claimed I don't understand this stuff, I have years at universities to prove otherwise and I've responded to your questions. You've avoided direct questions, even when simple 'yes or no'. It shows you are being knowingly dishonest.

You're a troll. Prove otherwise.

 

Since I have already been there.....

 

I can see you did not read the mainstream links I provided to enhance your "intelligence".

Where you are confused on sagnac, is that the receiver and the emitter are at rest with each other. Yet, they do not measure c and the mainstream aritlce I provided for linear sagnac is the same way.

So, how exactly to you propose to explain the at rest receiver and the at rest emitter not measuring c and also support the light postulate?

Naturally, I assumed with your complete lack of knowledge you would spend more time studying, but, I guess I was wrong because here you are again failing.

 

The comment about setting ones motion wrt to lots of photons was poorly worded

Poorly worded? No completely false.

You essentially claimed GR and SR are equivalent with your statement and I called you on it.

Setting yourself at rest with CMB is the same as setting yourself at rest with wrt to anything else is the stupidest statement I ever read. That was your statement.

You failed not me.