Age of Universe relative to what?

[TrickyDicky]

No, your suggestion is directly contrary to the postulates. The principle of relativity postulate says that there is no absolute rest. The light speed postulate says that c is absolute.

That's not what the special principle of relativity says. But nevermind that, there is obviously no absolute rest frame, I'm simply inquiring what is the difference between the rest frame of massive objects and light.

 

[ghwellsjr]

What I discussed in my last posts is independent of the one way vs. round trip speed considerations or the state of motion in which is measured.
do you think that motion is logically defined wrt a rest frame or not?

In Special Relativity, motion is defined with respect to an arbitrarily chosen inertial Frame of Reference. The motion we measure between two objects does not depend on any Frame of Reference. But we cannot measure the one-way speed of light under any circumstance.

And none of this has anything to do with a state of absolute rest. That's the point of contention. You say that because there is an absolute speed of light, there must also be an absolute speed of zero, which is wrong. Here's where you said it:

The key here seems to be that in order to have an absolute velocity (light speed) it appears natural that there has to be some absolute rest you reference that speed to, or otherwise how could c be absolute?

 

[ghwellsjr]

No, your suggestion is directly contrary to the postulates. The principle of relativity postulate says that there is no absolute rest. The light speed postulate says that c is absolute.

That's not what the special principle of relativity says. But nevermind that, there is obviously no absolute rest frame, I'm simply inquiring what is the difference between the rest frame of massive objects and light.

You state that the principle of relativity does not claim that there is no absolute rest. Are you changing your mind? First you argue for an absolute rest and now you say the opposite.

And you ask about the rest frame of massive objects (which exist) and the rest frame of light (which doesn't exist). It's getting very difficult to tell what you are asking or what you are promoting.

 

[TrickyDicky]

You state that the principle of relativity does not claim that there is no absolute rest. Are you changing your mind? First you argue for an absolute rest and now you say the opposite.

And you ask about the rest frame of massive objects (which exist) and the rest frame of light (which doesn't exist). It's getting very difficult to tell what you are asking or what you are promoting.

I'm not actually promoting anything, the OP was about the age of the universe so I'd say it involves GR rather than SR. SR is a theory limited to idealized spacetimes where there's only uniform motion, the special relativity principle was confined to a "local only" principle by Einstein in 1915, it's about time the die hard fans of SR take note; the phrase that originated this discussion was in the context of GR and it simply was exploring what "appears natural" logically and it's really no big deal, just ignore it.

 

[Dale]

That's not what the special principle of relativity says.

Yes, it is: "In the real world, there exists no such state of absolute rest. That's the content of the so-called principle of relativity, which is one of the basic postulates of the special theory of relativity."
http://www.einstein-online.info/elementary/specialRT/RelativityPrinciple

there has to be some absolute rest

there is obviously no absolute rest

 

[TrickyDicky]

Yes, it is: "In the real world, there exists no such state of absolute rest. That's the content of the so-called principle of relativity, which is one of the basic postulates of the special theory of relativity."
http://www.einstein-online.info/elementary/specialRT/RelativityPrinciple

Here your troll soul shines at its brightest, you ignore my previous post that settled the argument by giving it context, then you quote some words as if they were from the first postulate when in fact are taken from some website for kids, which suggests you haven't even read the original postulates. And finally you take a couple of sentences out of context and put them together for effect:as I said pure trolling. I must admit I had a good laugh too.

 

[Dale]

And finally you take a couple of sentences out of context and put them together for effect.

The quotes were deliberately brief, for effect as you mention, but hardly taken out of context. Or are you honestly going to try to claim that your posts 18, 22, 26, and 27 didn't all try to promote the idea of absolute rest?

Look, I'm glad you changed your mind, but don't try to pretend that I took something out of context when it was clearly in line with what you had been repeatedly saying in multiple posts.

 

[phinds]

Here your troll soul shines at its brightest, you ignore my previous post that settled the argument by giving it context, then you quote some words as if they were from the first postulate when in fact are taken from some website for kids, which suggests you haven't even read the original postulates. And finally you take a couple of sentences out of context and put them together for effect:as I said pure trolling. I must admit I had a good laugh too.

TrickyDicky, you are indeed living up to your name. "Out of context" ? Please.

 

[DaveC426913]

TrickyDicky, members of 6 years with 9000+ posts are not trolls, pretty much by definition, but regardless, we don't use that word here; it is an infractible offense and a personal attack.

If you have a beef with the argument, attack the argument, not the arguer. You'll notice right up until your trolling comments, everyone else was doing you the courtesy targeting your arguments, not you personally. Let's keep it that way.

 

[Dale]

It's OK, I understand his irritation with me, and I don't take offense at it. He changed his mind to agree with me, but instead of accepting it graciously and allowing him to save face I emphasized it and laughed at him. I provoked him, and I hope no infractions result.

 

[Snip3r]

You can only measure the round-trip speed of light

a quick question why can't 1-way speed of light be measured?

 

[Dale]

a quick question why can't 1-way speed of light be measured?

In order to measure the one-way speed of light requires two synchronized clocks. In order to synchronize the clocks you have to adopt some synchronization convention. Your measurement of the one-way speed of light then depends on the synchronization convention you have chosen, so you measure whatever number you chose to measure.

 

[TrickyDicky]

It's OK, I understand his irritation with me, and I don't take offense at it. He changed his mind to agree with me, but instead of accepting it graciously and allowing him to save face I emphasized it and laughed at him. I provoked him, and I hope no infractions result.

If it makes you happy to think that...lol oh, you enjoy provoking people eh noughty boy?, yeah, you got such power to make me change my mind to agree with you whenever you want.
Anyway why should you take offence if I just described your behaviour wrt a particular post, no personal attack involved at all. I'm sure you and your defenders are honourable men. (well maybe honourable dog in phinds case).

 

[Dale]

If it makes you happy to think that...lol oh, you enjoy provoking people eh noughty boy?, yeah, you got such power to make me change my mind to agree with you whenever you want.

Are you saying you didn't change your mind from

there has to be some absolute rest

in post 18 and emphasized in posts 22, 26, and 27 to

there is obviously no absolute rest

in post 31?

 

[TrickyDicky]

Do you mean you didn't read #34 yet?

And why don't you quote the complete phrase?

You are getting boring, I won't respond to any more of your instigations, don't find it fun anymore.

 

[Dale]

Do you mean you didn't read #34 yet?

If you had just posted 18 and 34 then I would have chalked it up to miscommunication, that from the beginning you had meant "it appears natural but it is wrong".

But in your followup posts (especially 22 and 26) you went far beyond that and explicitly stated that it didn't just "appear natural" but that logically "one implies the other" and "it is in the postulates". If anything your emphasis of the "seems natural" comment is out of context wrt the rest of your comments.

And why don't you quote the complete phrase?

For effect, as you already realized and I already agreed. It isn't misrepresenting your comments in any way, so I picked the most effective quotes.

I won't respond to any more of your instigations, don't find it fun anymore.

I am not surprised you don't find it fun anymore. I wouldn't either if I were in your position. But that is why, when I make a mistake or change my mind during a discussion, I usually admit it unambiguously. I do that to preempt anyone who would point out the change at my expense.

 

[phinds]

DaleSpam, your patience and equanimity amaze me. Thanks for setting a good example.

 

[Dale]

Thanks, although if I were really to be a good example I do feel like I shouldn't have rubbed it in his face in post 35. I am sad that he was banned or quit; I hope it is temporary.

 

[phinds]

Thanks, although if I were really to be a good example I do feel like I shouldn't have rubbed it in his face in post 35. I am sad that he was banned or quit; I hope it is temporary.

See that's why you're a good example. You're sad he was banned. I found him so offensive I'm glad he was banned. I just have no patience with his kind of behavior even though I sometimes have to struggle to keep myself from doing similar things, although I don't think even in my worst moments I'd call another forum member a dog, and I have no difficulty in admitting when I'm wrong.

 

[my_wan]

I didn't take TrickyDicky's quoted text to be contradictory in the context given. It seemed to me that if you take the quotes in the context given as contradictory implies relativity is contradictory. In fact I'll search up a quote from Einstein's book making a major point of saying that in the context of GR the constancy of light cannot be considered an "absolute" constant. Simply choosing to apply "absolute" in the sense certain fringe interpretations use it as a beating stick on relativity isn't necessarily valid. The speed of light is itself not an absolute constant, it is an observationally bound constant.

It is also possible to measure the one way speed of light, though I know of no explicit examples of it actually being done. Simply take a rotating hollow disk with holes on opposite side and note the RPM ranges in which a very short flash of light makes it through the disk to be detected, or some variation thereof.

 

[ghwellsjr]

It is also possible to measure the one way speed of light, though I know of no explicit examples of it actually being done. Simply take a rotating hollow disk with holes on opposite side and note the RPM ranges in which a very short flash of light makes it through the disk to be detected, or some variation thereof.

So you think a mechanical device can instantly transmit time information over a long distance? Sorry, that won't work.

 

[Dale]

It is also possible to measure the one way speed of light, though I know of no explicit examples of it actually being done. Simply take a rotating hollow disk with holes on opposite side and note the RPM ranges in which a very short flash of light makes it through the disk to be detected, or some variation thereof.

This seems similar to yuiop's proposal discussed in detail here:
https://www.physicsforums.com/showthread.php?t=461274

 

[my_wan]

So you think a mechanical device can instantly transmit time information over a long distance? Sorry, that won't work.

The device doesn't need to transmit time information. The distance between the two holes determine the timing, not clocks. The only variable involving a clock is the RPM of the disk. Are you saying I can't know the RMP of the disk over long distances? Even setups that have the light source on full time can work and the only thing measured is RPM and what RPM ranges did the light get through.

I can think of a few more approaches using a CCD, since you can actually tell where on a CCD the light hit and even position shifts of a frequency variance over the CCD. Creating a light source with a frequency spread like this is easy enough.

Never really cared much but I'll look over the links.

 

[Passionflower]

So you think a mechanical device can instantly transmit time information over a long distance? Sorry, that won't work.

We can always use subspace transmission to send a message really fast! ;)

 

[my_wan]

I see that thread still involved clocking flashes. There is no need. You have a rotating hollow pipe of a given length with an always on light source at one end, such that when the pipe points at the light source it goes through the pipe and detected at the other end. If the RPM is large enough the light never makes it through the pipe to be detected. The RPM is the only effective clock.

 

[my_wan]

It wouldn't even have to be a binary result, such that light was either detected or not. Since as the RPM increased the effective size of the hole is reduced which reduces the intensity of light as a result of a finite C. Neither would the relativity of rigidity play a role, since we know the the end results are always the same as if we presumed the relativity of rigidity played no role.

So here we have variation in both intensity and duration, where duration is not too significant in terms of the speed C, mostly just the effect of RPM alone, but intensity is. This would allow measurements with a finer grained variation in RPM and testable over a greater range of RPM.

 

[ghwellsjr]

Could you explain your experiment in more detail? I can't figure out what you are proposing. You started with a "rotating hollow disk with holes on opposite side" and now you're talking about a "rotating hollow pipe". Please describe the orientation of these rotating devices and where the holes are and how the light propagates, etc. I'm sure it's clear in your mind but it's not in mine.

 

[Dale]

I see that thread still involved clocking flashes. There is no need. You have a rotating hollow pipe of a given length with an always on light source at one end, such that when the pipe points at the light source it goes through the pipe and detected at the other end. If the RPM is large enough the light never makes it through the pipe to be detected. The RPM is the only effective clock.

The key objection, which applies to your idea, is this one:
https://www.physicsforums.com/showpost.php?p=3069207&postcount=14
with some follow-up here:
https://www.physicsforums.com/showpost.php?p=3070985&postcount=21
and here:
https://www.physicsforums.com/showpost.php?p=3075250&postcount=33

Your device let's through light at a specific speed due to its geometry. However, in theories with non-isotropic 1-way speeds of light (i.e. non-Einstein synchronization conventions) the length contraction is no longer isotropic and the device is geometrically distorted such that the light passes.

You simply cannot measure the one-way speed of light without assuming it.

 

[my_wan]

In the configuration it really makes no difference whether the pair of holes the light must pass through is a pair of holes on a surface of a cylinder or a hollow pipe in which the light must pass.

DaleSpam brings up a bigger issue. In the context of standard relativity the relativity of rigidity, as I've noted, makes no difference to the outcome. If "theories with non-isotropic 1-way speeds of light" are merely a different choice of synchronization then this is in principle perfectly allowed by relativity. Relativity only chose the synchronization procedure to match the maximal rate at which a given observer could obtain information about global coordinates as it was mathematically expedient, and only restricted it in such a way that effects could not precede causes. Choosing a different synchronization procedure in principle is no more physically significant than selecting a different coordinate choice. Trying to attach 'real' physical meaning to that is no different that arguing over which clock is really going slower, or which of two meteors the relational kinetic energy is 'really' located at.

Therefore, simple choosing a differing synchronization procedure which gives differing mathematical conditionals of space and time, has no physical meaning. Trying to require it to be measurable is like trying to measure the difference between 1 inch and 2.54 cm.

If the actual physics differs, outside of what is effectively a coordinate choice, then the anisotropy measuring procedure stands. That's why I mentioned my lack of real interest, because the only reasonable anisotropic C theories I seen are nothing more than an effectively different coordinate choice. Which might still provide some interesting numerical solutions to difficult problems and/or interesting perspectives.

We already know from GR that light speed does not constitute an absolute constant, only a relational constant.

The only people a measurable anisotropic C has any bearing on is the Einstein is wrong crowd. The people looking for some kind of absolute coordinate choice as if it is a physically real thing.

 

[ghwellsjr]

Could you explain your experiment in more detail? I can't figure out what you are proposing. You started with a "rotating hollow disk with holes on opposite side" and now you're talking about a "rotating hollow pipe". Please describe the orientation of these rotating devices and where the holes are and how the light propagates, etc. I'm sure it's clear in your mind but it's not in mine.

In the configuration it really makes no difference whether the pair of holes the light must pass through is a pair of holes on a surface of a cylinder or a hollow pipe in which the light must pass.

If you are going to claim that your method of measuring the one-way speed of light works, then you must have a way of measuring how long it takes for light to traverse some measured distance. Just saying that you have a rotating object with holes in it does not communicate what you have in mind.

If you have lost interest in defending your claim, I would at least urge you to read the wikipedia article on "one-way speed of light" to see that several attempts at measuring it have proved to be failures.