Speed of light

[Chris Peterson]

Can anyone answer, 'if light has no wavelength, is it still light'.

How could it be? Wavelength is related to energy by the Planck relation. If light had no wavelength, it would consequently have no energy (nor any momentum). I don't see how anything like that could describe what we call light.

[The Code]

http://blog.modernmechanix.com/2006/07/ ... han-sound/

everything and anything is possible. we just got to find out how.

bone anyone?

mark

[Qev]

While interesting, these cases don't do anything to undermine Special Relativity. No signal is ever transmitted faster than c in these experiments. This page goes into some detail why this is the case, for the caesium-gas experiment. There are also challenges to Dr.s Nimtz and Stahlhofen's interpretation of their quantum tunnelling experiment breaking the speed of light, also (there are links off of Dr. Nimtz's wiki page).

[Qev]

Do you have a comment on the two Germans who claim to have broken the speed of light?

I'm not aware of any such claims. People have modified the phase velocity of light to be both faster and slower than c, but that doesn't break any rules because no energy or information is traveling faster than light.

I think this is the paper that he's referring to: http://arxiv.org/abs/0708.0681v1 It seems to be a claim that they've transmitted a signal faster than c via quantum tunnelling.

[Qev]

Time has no matter or energy or any other form of particles or wave forms.

Neither do up, or left, or forwards?

I did not say that GR is wrong or right, just stated that time cannot be changed.

Then, depending on what you mean by 'changed', you're saying that GR is wrong, as time dilation is part of GR.

If you can prove one way or another than, what can I say.

Theories cannot be proved, only supported or disproved. And...

Expressing an opinion without science evidence is like asking for a chinese whisper.

GR has plenty of supporting evidence.

[Chris Peterson]

I think this is the paper that he's referring to: http://arxiv.org/abs/0708.0681v1 It seems to be a claim that they've transmitted a signal faster than c via quantum tunnelling.

Well, it's a very interesting report, mainly because they managed to come up with a practical way to measure the speed of tunneling- assumed by theory to be infinite, but never confirmed by experiment. However, I wouldn't say that SR is violated by this, but rather that the conditions created are outside the bounds of SR (just as GR defines behavior under conditions where SR breaks down). After all, in this experiment no photons traveled faster than c. It's important to remember that most theories in physics exist for specific conditions, and shouldn't be taken as absolute truths. Just as relativity actually solidifies Newtonian mechanics by more accurately defining its boundaries, so does QM have the potential (and perhaps in this case, has actually succeeded) in solidifying relativity in the same way. It should be noted that this is a report of an experiment to confirm what was already predicted by theory. In other words, this result doesn't change our understanding of the behavior of virtual photons.

As we've discussed in the past, scientific theories developed in the last century or longer (particularly in physics) have rarely been discarded because of later discoveries; rather, they are modified because their conditions of validity become better understood.

[harry]

G'day from the land of ozzzz

Hello Qev

Do you understand what relative time is?

and if you have evidence to support what you say or some form of logic that time can change.

Time that is determined by the speed of EMR is in many case relative to the time of communication.

Some one asked if I was tired when I wrote the last post.

YEP!

This is interesting
The Myth of the Beginning of Time
http://www.sciam.com/article.cfm?id=the ... ng-2004-05

Was the big bang really the beginning of time? Or did the universe exist before then? Such a question seemed almost blasphemous only a decade ago. Most cosmologists insisted that it simply made no sense--that to contemplate a time before the big bang was like asking for directions to a place north of the North Pole. But developments in theoretical physics, especially the rise of string theory, have changed their perspective. The pre-bang universe has become the latest frontier of cosmology.

[Qev]

I guess it really underlines how virtual photons don't have to play by the same rules that real ones do.

I'm assuming that there's a catch here that prevents this method from actually being useful for signalling faster-than-c (like their is in all the other 'faster-than-c' setups)?

[aristarchusinexile]

Can anyone answer, 'if light has no wavelength, is it still light'.

How could it be? Wavelength is related to energy by the Planck relation. If light had no wavelength, it would consequently have no energy (nor any momentum). I don't see how anything like that could describe what we call light.

So at what point does light cease to be light, and what does it become? I believe I have seen written here that space is curved but the distances involved actually flatten space. Although I see in a post above, Chris, you say space is only thought to be flat. Could the same effect occur in wavelength? I have no point in asking this question, no agenda, mere curiousity.

[aristarchusinexile]

While interesting, these cases don't do anything to undermine Special Relativity. No signal is ever transmitted faster than c in these experiments. This page goes into some detail why this is the case, for the caesium-gas experiment. There are also challenges to Dr.s Nimtz and Stahlhofen's interpretation of their quantum tunnelling experiment breaking the speed of light, also (there are links off of Dr. Nimtz's wiki page).

I'm glad that url included diagrams.

[aristarchusinexile]

Yes, this can be tiring stuff, which makes it easier for me to let go of my firm grip on what I think I understand, in favour of considering other considerations.

"Was the big bang really the beginning of time? Or did the universe exist before then? Such a question seemed almost blasphemous only a decade ago. Most cosmologists insisted that it simply made no sense--that to contemplate a time before the big bang was like asking for directions to a place north of the North Pole. But developments in theoretical physics, especially the rise of string theory, have changed their perspective. The pre-bang universe has become the latest frontier of cosmology."

Thanks Harry. The answer seems simple, because eternity is accepted by practically everyone (I am led to believe) as simple fact; and time, as is normally considered, no matter how lengthy in duration, is merely a blip in eternity. However, as "universe" is described as 'all the matter which exists', the investigation of the pre-bang universe hinges on the theory that the universe was created from an exploding singularity. So, that 'beginning' hinders creative thought about what might have been "in the beginning", because every thought must relate to a singularity which might not have existed. Also, if time is not merely measurement of part of eternity, but is something which directly effects energy and matter, then the investigation becomes more complicated. I will investigate 'relative time'.

[aristarchusinexile]

I got this: "Space and time are now dynamic quantities: when a body moves, or a force acts, it affects the curvature of space and time---and in turn the curvature of space-time affects the way in which bodies move and forces act. Space and time not only affect, but are also affected by everything that that happens in the universe." Hofstadter would call this a Strange Loop." from near the end of this:http://www.ram.org/ramblings/science/ti ... ative.html "Time is Relative".

To me, this seems confirmation that time is a quality which affects matter, therefore it must not be simple measurement.

From Wiki: "Energy quality the contrast between different forms of energy, the different trophic levels in ecological systems and the propensity of energy to convert from one form to another." I suggest again, not to be redundant or emphatic, mostly to remind myself, that time is a relative of energy, an energy itself.

Oops, a glitch from Wiki: "The universe is defined as everything that physically exists: the entirety of space and time, all forms of matter, energy and momentum, and the physical laws and constants that govern them. However, the term universe may be used in slightly different contextual senses, denoting such concepts as the cosmos, the world or Nature."

So, is the Wiki definition wrong to include time? If correct .. there was no beginning to the universe, perhaps only a beginning to the matter and energy in the universe.

By the way, Harry, I don't see this as a divergence from jets. If time is an energy which is compressed inside a black hole or a black hole's surroundings, it can help account for the length of long jets.

[Qev]

and if you have evidence to support what you say or some form of logic that time can change.

Well, what exactly do you mean by 'time cannot change'? Are you referring to time dilation? Time travel?

[Chris Peterson]

So at what point does light cease to be light, and what does it become?

The point is, it doesn't. You can reduce the energy of a photon to arbitrarily close to zero, but you can never reach zero energy. There are subatomic interactions that can convert a photon to different forms of energy, of course, but these involve multiple particles. You can never redshift all the energy out of a photon.

I believe I have seen written here that space is curved but the distances involved actually flatten space. Although I see in a post above, Chris, you say space is only thought to be flat. Could the same effect occur in wavelength?

Measurements only place a boundary on how curved space might be; it is either flat or very close to it. I think most cosmologists believe it is probably flat, but there is some uncertainty remaining. I'm not sure, though, what you're asking when you compare the flatness of the Universe to something happening to the wavelength of a photon. Over cosmological distances, redshift from the expansion of space lowers the energy of photons. But as noted above, it can't get to zero (and in practice doesn't come close, given the times and distances involved).

[aristarchusinexile]

I'm not sure, though, what you're asking ...

That makes two of us, Chris.

[makc]

My minutes-old awareness of chronons leads me back to 'Galaxies trailing their spirals', where I propose Galaxies create time, making it appear in photos of spiral galaxies face on that their spirals are trailing behind the nucleus, whereas no edge on photos of spirals galacies exhibit the appearance. You might remember my proposed 'time funnels'.

Weren't it posts like these that got Sputnick banned? I think someone needs a reminder here.

P.S. Thanks for some good quotes.

[makc]

and perhaps in this case, has actually succeeded

Isn't QED (a theory supposedly used in a paper) relativistic theory?

You can reduce the energy of a photon to arbitrarily close to zero, but you can never reach zero energy... You can never redshift all the energy out of a photon.

Now this is interesting, can we all have a bit more elaborate explanation why?

[Chris Peterson]

and perhaps in this case, has actually succeeded

Isn't QED (a theory supposedly used in a paper) relativistic theory?

It is, but I don't know how this relates to my earlier comment.

You can reduce the energy of a photon to arbitrarily close to zero, but you can never reach zero energy... You can never redshift all the energy out of a photon.

Now this is interesting, can we all have a bit more elaborate explanation why?

Any process I can think of that increases a photon's wavelength is continuous and multiplicative. You need an infinite amount of time with such a process to achieve an infinite wavelength (zero energy). In order to get there in a finite time, you need some sort of non-continuous, additive process. I can't imagine any natural process like that. Do you know of any?

[JimJast]

[space] is either flat or very close to it

In Einstein's theory the flat space makes no sense. If space were flat the universe would have to be infinite, which seems a non physical solution. The space has to be curved to close the universe into a 3-sphere. One may estimate that the radius of curvature of space is over 4 Gpc, which might be tough to test obserationally.

[makc]

It is, but I don't know how this relates to my earlier comment.

well they are saying in the article that their results comply with QED. and as such, they cannot violate relativity, even if that's what they are also saying.

Any process I can think of that increases a photon's wavelength is continuous and multiplicative. You need an infinite amount of time with such a process to achieve an infinite wavelength (zero energy). In order to get there in a finite time, you need some sort of non-continuous, additive process. I can't imagine any natural process like that. Do you know of any?

How about Universe expansion? What happens to light emitted by most distant objects leaving the limits of visible universe?

edit: this is somewhat similar to light emitting things passing through BH horizon. in case of BH, physicians were able to dodge the question by saing that, from the perspective of distant observer, it would take an infinite time to cross the horizon, and so red-shift-to-zero never actually happens. only this time it doesnt seem to be the case, since accelerated universe expansion means that everything will be out of visible universe in finite time, doesnt it?

[Chris Peterson]

How about Universe expansion? What happens to light emitted by most distant objects leaving the limits of visible universe?

Is that happening? That is, is there material that we were causally connected to that we became disconnected from?

edit: this is somewhat similar to light emitting things passing through BH horizon. in case of BH, physicians were able to dodge the question by saing that, from the perspective of distant observer, it would take an infinite time to cross the horizon, and so red-shift-to-zero never actually happens. only this time it doesnt seem to be the case, since accelerated universe expansion means that everything will be out of visible universe in finite time, doesnt it?

I'm not at all sure that's the case. Of course, if you are causally disconnected from something, does that mean that it has been redshifted to zero wavelength, or simply that it is "around a corner" and you aren't receiving any signal? It seems to me there's a difference between receiving no photons, and receiving photons that have been highly redshifted. Something to think about, anyway.

[harry]

G'day from the land of ozzz

You got to know that, I'm not a smart cookie.

Just learning as I go.

In the last 2 years my reading because of Neried has exploded basically in understanding compact matter, degenerate matter and the formation of jets and yes Aris is right time is of importance to the topic.

Hello Qev

Actual Time cannot change, relative time can because the speed of EMR can be altered during experiments here on earth and when EMR comes close to compact objects such as Neutron stars and so called Black holes that have densities 10^17 to the theoretical 10^35 Kg/m3 that are able to crete vector fields strong enough to attract EMR and in the case of black hole prevent it from escaping. So! when we talk of communication relative time will alter.

[makc]

your reasoning is like that in the tale of Achilles and the Tortoise. it is true that f(x) = exp(-x) will never reach 0, but g(x) = 1 - x will reach g=0, cross it, and extend forever into negativity. so I am asking here what makes you think it is f(x) situation, and not g(x)?

edit; any way, what experimental data says, will there be a big rip or no? I've found some article that says no, but it doesnt look very credible. would the real astronomer please enlighten us? Chris? come on. give us some material

[aristarchusinexile]

Relativity: "A Quantum Threat to Special Relativity" Scientific American, March 09 - David Z. Albert & Rivka Galchen http://www.sciamdigital.com/index.cfm?f ... 6D4FE32B9D - and I thought the whole article was included when I copied that link, but then I checked and found only a preview .. so I can't guess what occured.

This stuff is probably old hat to many of you here on the forum, but perhaps not to all, and I found it particularly interesting, well written and stimulating .. although the more I consider this post that I'm composing the more I know I have to give more thought to locality and non-locality: but at this point I consider: 1 - distance an illusion like a mirage, although I'll have to explore the meaning of the word 'illusion': 2 - the reality which we see around us is reality, but what is unreal is our perception as to how limited we are in our ability to affect reality, either by "local" or "non-local" methods.

An interesting point the article makes is that "no material (my italics) carrier of a message can be accelerated from rest to speeds greater than that of light." I can't help but consider two things: 1 - energy added to a message in transit might boost the message faster than light: 2 - exploring the immaterial will probably enable instantaneous transmission.

I also found interesting this http://en.wikipedia.org/wiki/Alcubierre_drive .. especially because of the Speedy Conzalez connection.

[aristarchusinexile]

your reasoning is like that in the tale of Achilles and the Tortoise. it is true that f(x) = exp(-x) will never reach 0, but g(x) = 1 - x will reach g=0, cross it, and extend forever into negativity. so I am asking here what makes you think it is f(x) situation, and not g(x)?

edit; any way, what experimental data says, will there be a big rip or no? I've found some article that says no, but it doesnt look very credible. would the real astronomer please enlighten us? Chris? come on. give us some material

Thanks for the link, Makc. The big rip, in which the stuff of atoms fly apart also, seems to be the way the present universe is "ordained" to end, giving place to an immaterial existance, immaterial in my sense meaning not of matter, perhaps relating to the "immaterial" sense of George Berkley, but I can't understand his sense right now.