Neutrinos faster than the speed of light?

"For measuring time at a place which, relatively to the origin of the co-ordinates, has the gravitation potential Φ, we must employ a clock which – when removed to the origin of co-ordinates – goes (1 + Φ/c²) times more slowly than the clock used for measuring time at the origin of co-ordinates."

http://relativitybook.com/resources/Einstein_gravity.html

This is the sentence just before what you quoted from Einstein. It is not to correct the speed of light. The equation is for correcting clocks in order so that they can both measure the same speed of light.

"The principle of the constancy of the velocity of light holds good according to this theory in a different form from that which usually underlies the ordinary theory of relativity."

 

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[video=youtube;9XjS4I4oQDY]http://www.youtube.com/watch?feature=player_detailpage&v=9XjS4I4oQDY[/video]

 

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You can't prove light is consant by definition and that URL says nothing of the sort. The second postulate of special relativity states that the speed of light has the same value in all inertial frames of reference. That's true and nobody is saying that it isn't. What Einstein was later to address is what the speed of light is when the frame of reference is not an inertial one and he was able to show that it doesn't have the same value, i.e. is not constant, when the frame of reference is not an inertial one. And even then when it's not measured locally. Grumpy keeps missing those caveats.

The URL you gave talks about the fact that the meter is defined using the speed of light. That's all its saying. It uses the fact that the speed of light is invariant and always locally has the same value. This is another thing that Grumpy keeps missing, i.e. the non-local part. Ohanian explains this but he's not willing to pick up that text and learn. And nobody can force him to learn.

There are plenty of derivations which prove that the speed of light, while constant and invariant in inertial frames, is not constant in non-inertial frames. Einstein demonstrated this in his 1911 paper that I quoted above. If you strongly believe he made a mistake then I challenge you to prove that his derivation is wrong by pointing out where you think Einstein (and ever other GR expert in the world) screwed up? Are you up to that challenge? You do know, don't you, that every single expert in general relativity that exists today states that light slows down in a gravitational field, right? All you have to do is pick up almost any GR text and it will show you how to prove it.

If you accept that challenge I await your proof. Meanwhile here's the proof that Einstein was right. If you're like Grumpy who can't follow the math then please let me know.

http://home.comcast.net/~peter.m.brown/gr/c_in_gfield.htm

 

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pmb, I don't see the part you disagree with. In the geometrical picture, there are no gravitational forces. For the algebra in a cartesian coordinate system, there are ("fictitious") gravitational forces because the partial derivatives in cartesian coordinates are not geometrically informed. Same physics, different pictures, different derivatives, different definitions of time and acceleration and force.

 

That's the part I disagree with. In the geometrical picture there the gravitational force is not a 4-force. In the geometrical picture there is a gravitational force - it's an inertial force. What was called "fictitious" forces by Newton are called "real" by Einstein.

This was explained by Albert Einstein in the February 17, 1921 issue of Nature where he wrote

This is what I meant when I said that the Coriolis force and the centrifugal force which used to be called fictitious by Newton are called "real" by Einstein. Those are inertial forces tool.

 

Pmb. If in the geometrical picture a bodies energy and angular momentum are constant in free-fall, how are you defining force here? I can see once the body contacts the ground there will be a change in the bodies energy and angular momentum, buts that comes about by contact. In the geometrical picture where is the force on a free-falling body?
A body following a path of constant energy and angular momentum in an altered spacetime gives the geodesic.


Thanks everyone for an interesting thread, I’m learning.
That’s not sarcasm.

 

You are saying that it isn't. You are saying that since signals are observed to slow down in the presence of strong gravitational fields the speed of light has changed. You are basing this on the Shapiro test, and in so doing you are declaring D (the calculated distance to Venus) to be a number that is calculated both in the inertial frame (making the correction for GR) and in the non-inertial frame (making no correction). This is why I keep telling you that you're playing games with reference frames, and this is why your posts are not only nonsensical, but they violate the most basic rules of logical argumentation, not to mention the first principles of science.

Since no one cares about non-inertial frames other than to correct for GR, that entire line of reasoning is moot. It doesn't change the fact that the speed of light is actually constant. Your manic insistence that the non-inertial reference frame is somehow meaningful in understanding first principles is futile. Fundamental definitions like "speed is the derivative with respect to time of displacement" become meaningless in the context of non-inertial frames, at least not without referencing all descriptions of the physical phenomena (in this case a propagating photon) to an inertial frame (e.g. doing the corrections per the Lorentz rotation).

Grumpy is way ahead of you. To attack him is therefore to attack yourself. There is no caveat of the kind. The caveat is that the non-inertial frame, as you are attempting to apply it, is useless to the question of defining the speed of light. It's meaningless. You either go back and revamp the definition "speed is the derivative with respect to time of displacement" to some non-inertial form, such as "speed is the derivative with respect to relative time of relative displacement", or else you stick with the common speech and you accept that all speed measurements are done in inertial frames, even when the frame is not physically purely inertial (i.e. we're all in a gravitational field). And in so doing you admit that there will be corrections for GR not because the speed of light changed but because the space and time the light traverses have, to the observer, changed --and nothing more.

Ugh.

I guess it depends on which Ohanian text you are selling here. If you mean the one that lampoons Einstein, then you should should read it yourself and explain why you are relying on Einstein as an authority in reference to a variable speed of time. No, Grumpy is right.

All of which is useless information.

You mean the way Einstein screwed up, according to Ohanian, who (characterizing his math) said, "The mistake is the sort of thing every amateur mathematician knows to watch out for" ? But since you haven't even figured out what coordinate speed means you're not really in a position to challenge anybody, so no one is taking this seriously. The challenges are entirely in your court.

You do know, don't you, that none of them are buying what you're selling? The statement "slowing down in a gravitational field" is in no way the same as saying "the speed of light changed" and nowhere do you find any textbook that says they are the same. So you might as well drop the appeal to authority since there are no authorities on your side.

In your case it requires the guidance of a seasoned professor, since the home schooling hasn't worked out for you. The rest of us may grab an old dog-eared book to double check something in a table or just to work end of chapter problems while fooling around with LaTex. But we're not in the dark about the content and meaning of the material in those books, because we had plenty of help from our instructors and advisors whenever we got stuck in a rut. And some of us joined technical societies where we could slog through the challenging material with the help of partners, without having to expose all of our weaknesses to the faculty. In your case you need a full bore showdown with an instructor, which is only going to happen if you enroll in a class on relativitity. Until then you're firing blanks. You are your own worst enemy when it comes to physics. So go fix that. You're obviously not responding to the free help you've been given here; maybe you need to actually pay some tuition to understand the value of an education.

The key to understanding the peter brown web page isn't following the klunky way he derives coordinate speed but rather the nonsensical annotations he made which convert the actual formulations to something worse than common pseudoscience. It's better characterized as common fallacy, the kind most of freshman grapple with when confronted with discussion openers like "when is Baden-Baden going to arrive at the train?"

(I put that in the third person since you're so intent on referring folks to your web page.)

 

pmb

But I'm NOT the idiot claiming variable lightspeed.

There is no such thing as light travelling through a vacuum in spacetime at any other speed except AT lightspeed. That is a simple, massively verified, FACT. It has never been falsified(misapplied math or no). If light is EVER measured to move through spacetime at ANY speed except lightspeed, we won't be hearing it first from you, we will be reading it on the front page of every media outlet known. Remember the "Faster than light Neutrino" that this thread started with? Turned out to be a COMPUTATIONAL error due to a loose fiber optic connection. You are making a COMPUTATIONAL error based on faulty assumptions about distance and time in the experiment Shapiro performed, and getting an erroneous conclusion(slow light speed)from faulty understanding. You are in no way "proving" your understanding is valid(even if your computations are dead on).

Einstein's whole thought experiment series that led to Relativity started with that one assumption(which has survived every test since). That value is intimately tied into the Universe, energy and matter are equivalently proportional to the square of that value, no mass can travel at that speed, time and space warp in proportion to that speed, and they become INFINITELY warped at that value(and no other). How many more ways does it have to be pointed out to you before you say to yourself "Hmm, this value is important."? Lightspeed is a constant and anyone who says otherwise doesn't know crap about Relativity. It makes it easy to tell who the fools are, though. Stop making yourself look so foolish.

You simply do not know what you are talking about and you don't seem to have an ability to self correct. You certainly are totally screwed up concerning understanding Relativity. You seek out quotes that you can misunderstand and misrepresent or cranks who know no more than you do to bolster your continued erroneous conclusions when a simple perusal of "A Brief History of Time" by Hawking would straighten you out in an afternoon(the information in that book is solid and easily understood). Forget Shapiro(you totally misunderstand the implications, as does Shapiro, evidently), forget Ohanian(His statements are obviously leading you astray)and especially forget Peter Brown(he's even more wrong than you are). You're an ignorant crank at the moment, but only you can correct that but it isn't going so well. You aren't, evidently, stupid or unable to understand Relativity, but you aren't putting forth an effort to do so. You've gotten stuck going down a dead end path(variable lightspeed), you need to turn around and get back to the well worn path that Einstein trailblazed and many others improved upon. Start where Einstein did. Assume constant lightspeed and go from there. If you follow his path you will soon catch up to the rest of us who have been following it for decades. The weeds are full of idiots who thought they knew better, don't continue to be one of them.

"I like Scotch, Scotchy, Scotch, Scotch."

Ron Burgundy

Well, I like Cosmology and Astronomy

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Grumpy

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Oh, those are all galaxies and globular clusters from about 9 billion years ago/away. Similar clusters that are a few billion years closer to us are "dead", they have very little gas and almost no star formation, but these are all on fire with massive star formation(most of the red color is due to expansion and apparent speed, not local speed through spacetime).

 

Give it up Grumpy. You demonstrated to me beyond all doubt that, like the other layman here, you don't have what it takes to comprehend this phenomena. Hence both you're refusal to read the GR literature and if you did choose to read it your inability to grasp it. You proved that by claiming Shapiro was wrong when you read what he says about it in his paper in Physical Review. You've already convinced me that there's no hope for you whatsoever and that you're going to be pumping out tis misinformation with the rest of the crackpots. And this is the very reason why this forum has such a terrible reputation.

 

Guess I’m being ignore by pmb.
It must be below him to reply to my question in post #226, about force in the geometrical spacetime model.
But, If your reading this pmb, here’s a quote from” Exploring Black Holes” first edition page 4-5.

And a quote from the second edition…page 2-2

So, pmb, in the geometrical spacetime model, where is the force you claim to be in that model?

 

nimbus

pmb ignores what he cannot answer, he soon runs out of people he does not ignore. Sure sign that he knows he's a crank, he runs from those who know better than the crap he spews.

If you really want a good grounding in Relativity, what time and space are and the history of our Universe, Steven Hawking is much easier to understand than most and "A Brief History of Time" will tell you exactly what I have been saying in much better terms and detail. And Hawking understands that until you understand the framework, the math will do you little good. pmb doesn't understand Relativity, he is making huge, basic mistakes before he does his first calculations. He wants to argue the validity of his math, not it's application to reality(or lack thereof).

Grumpy

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That's it. Enough is enough. I can no longer tolerate so much misinformation being passed around by layman who have neither the ability nor the desire to learn the correct physics. And even if they did it's clear that they have too much pride and are too arrogant to admit their mistakes. To claim that Shapiro is wrong when in fact it was Grumpy telling me to listen to him when he thought Shapiro would agree with him is so sad that I can no longer let me name be associated with a forum whose name has so little respect for this all over the internet.

If and when the forum moderators and administrators choose to prevent the likes of Grumpy, brucep, niumbus etc. from propagating so much bad information and trying to convince the members of this forum to ignore everything the GR community is trying to teach them tjhen perhaps the forum won't be frowned upon so badly. Until then I won't be associated with such horrible science.

Shame on all of you, especially brucep who should know better since he has Exploring Black Holes which he's choosing either to ignore to twist out of all recongnition. Shame on you Pew.

 

pmb

:wave:

 

Hi Grumpy, pmb.

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I was just reading-only hoping to identify exactly where the disagreement lay between you two (sorry to see that mutual frustration is engendering ill feeling into the discussion between you two; I hope this ill feeling will be shortlived!

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).

Anyhow, Grumpy, I was just reading here, but something you said to pmb struck a jarring note with what I read you saying to me in another thread. I would like it clarified (if you have time) so that I can better understand your 'take' on the matter of lightspeed and warped space etc as it relates to your and pmb's respective arguments.

Specifically in this thread, in post #228 (I have bolded the particularly relevant bits), I read you to say to pmb:

That rang a bell, and I recalled what you said to me in the "Time is NOT the 4th Dimension" thread (post #324 therein; again, I bold the particularly relevant bit):

Hence I ask now:

1) Wasn't the hypothetical BB 'spacetime' during inflation at 'maximum warp' condition; such that any 'warping of spacetime' at present by a photon is almost neglible in comparison (again, I allow for the sake of discussion your 'accepted' hypothesis/argument of BB scenario/states etc)? and...

2) How do you reconcile your statement to me, ie, "there was NO lightspeed limit" until later on in the "spacetime inflation/expansion process" BB process, with your statement to pmb that you are "NOT claiming variable lightspeed"?


So as to forestall any possible misunderstanding/contradictions, I have need of further clarification as to what you mean in the context of both statements taken together. Once I have the needed clarification I can again confidently proceed to read-only with the view to properly understanding in consistent context your exchange with pmb on these aspects. Back tomorrow. Thanks!

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PS: Grumpy, pmb, please try to patch things up between you two, as I like and respect you both too much to watch such falling out over possible misunderstandings due to potentially cross-purpose exchanges on the subtleties involved in these aspects. Good luck to both of you!

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Of course it's not sarcasm. It's obvious to 'those or us' who enjoy this science.

 

'End of chapter problems' is the extent of it for me. LOL. Very informative post. Thanks for writing it down.

 

At maximum warp? I think someone has been watching too much star trek.

Something like a photon moves through the vacuum at a speed determined by a ratio of electric constant and the magnetic constant to a negative power.


Rpenner

''nimbus,
Force is a term of art.

In a geometrical theory about the manifold of space time, there can be no gravitational forces. ''



Your physical understanding of nature is somewhat lacking. Maybe that is because you come across as a pure mathematician?

Either way, the geometrical understanding of the spacetime manifold is because of gravitational forces. Geodesics, implying the word ''geometry'' of moving systems are determined from the gravitational influences which deform space and time the same manifold we began with.

 

Funnily, and I have high respect for Michio, he made the same comments when asked about the faster than light particles.


He said it would have been a break down of relativity as we know it. This is the only circumstance I have found him incompetent in his claims. There is no theory in relativity which forbids faster than light particles. I haven't watched the whole video but I will never forget what he said when this was believed to have been discovered.

 

pmb you told me you were leaving this forum at least twice in the last 2 weeks. But you're still here, I see. Which is fine by me. But you do seem to be rather on your own and not have managed to convert anyone to your way of thinking. I draw my conclusions accordingly.