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whatdofisheat
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how can the area or distance between two objects getting larger cause something traveling between them to strech?
misskitty said:Self, so let me see if this is right:the wave length the only portion of the light that would be affected?
Nope. The individual photons do indeed lose energy as space expands.misskitty said:I don't think it is so much as light loses energy. Because energy can neither be created nor destroyed. The light travels through space (it's medium) and as its medium expands the distance between molecules of space is greater which makes it more difficult for the light to travel. Not by much though. Anyway, the energy is more spread out making it seem as though there is less of it, but there really isn't. I'm pretty sure that's how it works. My physics class is studying light and sound waves, so based on that information I'm pretty sure.
firsty - sound waves are quite different to photons. Why would you expect them to behave the same way? What makes you think that photons are in any way analagous to sound waves?Chronos said:I'm not sold on that. Do sound waves lose energy when the source is receeding?
Light is EM waves propagating through EM fields. When light is redshifted, the frequencies of the light waves are reduced and the effective wavelengths increase.moving finger said:firsty - sound waves are quite different to photons. Why would you expect them to behave the same way? What makes you think that photons are in any way analagous to sound waves?
I could equally well argue that light is comprised of quantum objects which we call photons, which propagate according to the configuration of mass/energy in their vicinity.turbo-1 said:Light is EM waves propagating through EM fields. When light is redshifted, the frequencies of the light waves are reduced and the effective wavelengths increase.
Please can you provide me with the details of this post?turbo-1 said:As I pointed out in another post recently, Einstein never modeled light as photons, but as EM waves propagating through the aether. He was unable to reconcile the aether with GR, so he claimed that it had NO properties sensible to us.
Einstein was awarded the Nobel prize for explaining the photoelectric effect on the basis of light being composed of discrete quantum objects.turbo-1 said:He knew that it had to exist to allow the propagation of light through space, but he couldn't get it to make sense in GR.
misskitty said:...I don't think it is so much as light loses energy. Because energy can neither be created nor destroyed. The light travels through space (it's medium) and as its medium expands the distance between molecules of space is greater which makes it more difficult for the light to travel. Not by much though. Anyway, the energy is more spread out making it seem as though there is less of it, but there really isn't. I'm pretty sure that's how it works. My physics class is studying light and sound waves, so based on that information I'm pretty sure.
...
marcus said:Some people have ideas about "where does the lost energy go?" but there is no straightforward answer. As far as the light knows, over 99 percent of its energy has been destroyed. I am NOT talking about "thinning out" which happens too (fewer photons per square kilometer) but about the loss of over 99 percent of an individual photon's energy due to spatial expansion.
moving finger said:
I respect your acceptance of the particle/wave duality. I suggest to you that you might look at this duality as an interesting convergence of classical and quantum physics. Classical physics tells us (quite appropriately) that energy travels as waves propagating through fields. Quantum physics tells us that EM waves collapse and can act as if they are point sources, and the likelihood that a point will be expressed at any location is a function of the sum of the magnitudes of the probabilities involved. Feynman gave some great lectures on this at a non-technical level. you'll need a few spare hours to view these, but they are priceless!moving finger said:I could equally well argue that light is comprised of quantum objects which we call photons, which propagate according to the configuration of mass/energy in their vicinity.
show me an experiment which you think demonstrates light behaving as a wave and I'll show you an alternative interpretation based on the motion of discrete quantum objects.
when space expands the energy of individual photons in that space is reduced, this is interpreted as an increase in wavelength of the light (ie redshifting).
I can't locate the post right now, but here is the lecture that Einstein gave in 1920, after struggling for years to get rid of the aether. He finally reconciled himself with the aether because it is essential for EM wave propogation. Because he couldn't accept the idea that the aether represented a reference frame against which proper motion might be sensed, he claimed that it had NO properties other than the ability to propogate EM waves. This was probably not the right assumption, as demonstrated by the Unruh Effect. The assumption did not accord with the Machian view of space, either, although that is a bit more theoretical, modeling rotation and proper motion as if they had to be measured relative to the reference frames of every piece of matter in all the universe. I think Mach's aether failed only because he did not have an idea of the enormity of space, and neglected to treat the aether as a local reference fram.moving finger said:Please can you provide me with the details of this post?
Yes, but Einstein had a great deal of difficulty accepting the particle/wave duality of light that many seem to credit to his work.moving finger said:Einstein was awarded the Nobel prize for explaining the photoelectric effect on the basis of light being composed of discrete quantum objects.
Hi ChronosChronos said:This is my favorite myth buster episode regarding tired light:
http://www.astro.ucla.edu/~wright/tiredlit.htm
Please consider that cosmologically redshifted photons are also time dilated. Photons from a z=2 supernova are only half as energetic as those from a z=1 supernova - but you receive twice as many of them due to time dilation effects. I don't see any missing energy.
I do not accept it the way you perhaps think I do.turbo-1 said:I respect your acceptance of the particle/wave duality.
I disagree – I think the opposite! IMHO it is precisely the continued attempt to force QM to fit the classical paradigm of “either wave or particle” that prevents us from truly understanding what is going on at the quantum level.turbo-1 said:I suggest to you that you might look at this duality as an interesting convergence of classical and quantum physics. Classical physics tells us (quite appropriately) that energy travels as waves propagating through fields.
This is what I mean by “misconceptions”. There is (IMHO) in fact no “EM wave” as you call it, because quantum objects are not waves, and there is no “collapse” and it is not the case that they “can act as if they are point sources” – these are all consequences of trying to force quantum objects to fit your intuitive macroscopic paradigm of “either wave or particle”, when in fact they are neither wave nor particle.turbo-1 said:Quantum physics tells us that EM waves collapse and can act as if they are point sources, and the likelihood that a point will be expressed at any location is a function of the sum of the magnitudes of the probabilities involved.
IMHO, the problem is the one I have outlined above. Quantum objects are not “waves” which “collapse to point-like functions”, this is our distorted attempt to understand QM assuming the macroscopic “either wave or particle” paradigm.turbo-1 said:This tendency of waves to collapse to a point-like function and the way that atoms on the receiving end must exhibit quantized (fixed-energy) reactions have made us comfortable with the concept that light actually travels in quantum-energy packets. This is not true.
I respect your belief, but IMHO I do not think we can ever hope to properly understand quantum objects as long as we continue to try and shoehorn them into an “either wave or particle” paradigm. Your picture carries with it all of the ugly “collapse” implications as the “wave” (spread out over the entire universe I might add!) suddenly stops being a wave and all of it’s energy is suddenly collected and focused into a single “particle” at the moment of detection.turbo-1 said:I think that light exists as waves propagating through EM fields, and that the waves decrease in energy as they propagate through the field, and that our detectors can only respond in quantum steps, leading us to think (erroneously) that light can only impinge upon our receptors with fixed energy levels and in point sources.
Another reason for rejecting the “wave” picture of quantum objects.turbo-1 said:I can't locate the post right now, but here is the lecture that Einstein gave in 1920, after struggling for years to get rid of the aether. He finally reconciled himself with the aether because it is essential for EM wave propogation.
IMHO Mach’s principle is alive and kicking, and I believe will eventually need to be accounted for in a quantum-mechanical theory of gravity, whereas I don’t see any hope for the aether (except insofar as Mach’s principle suggests a reference frame dictated by mass-energy which could be called the “aether”).turbo-1 said:Because he couldn't accept the idea that the aether represented a reference frame against which proper motion might be sensed, he claimed that it had NO properties other than the ability to propogate EM waves. This was probably not the right assumption, as demonstrated by the Unruh Effect. The assumption did not accord with the Machian view of space, either, although that is a bit more theoretical, modeling rotation and proper motion as if they had to be measured relative to the reference frames of every piece of matter in all the universe. I think Mach's aether failed only because he did not have an idea of the enormity of space, and neglected to treat the aether as a local reference fram.
turbo-1 said:http://www.tu-harburg.de/rzt/rzt/it/Ether.html[/QUOTE]
Thanks, I shall read with pleasure.
moving finger said:Einstein was awarded the Nobel prize for explaining the photoelectric effect on the basis of light being composed of discrete quantum objects.As many of us still do!turbo-1 said:Yes, but Einstein had a great deal of difficulty accepting the particle/wave duality of light that many seem to credit to his work.
"Niels Bohr brainwashed a whole generation of physicists into believing that the problem had been solved"
Murray Gell-Mann
This is what Einstein had to say about duality :
“It is unreasonable for a single photon to travel simultaneously two routes. Remove the half-silvered mirror, and one finds that one counter goes off or the other. Thus the photon has traveled only one route. It travels only one route, but it travels both routes; it travels both routes, but it travels only one route. What nonsense! How obvious is it that quantum theory is inconsistent! Bohr emphasised that there is no inconsistency. We are dealing with two different experiments. The one with the half-silvered mirror removed tells which route. The one with the half-silvered mirror in place provides evidence that the photon traveled both routes. But it is impossible to do both experiments at once”
Albert Einstein
Further evidence (IMHO) that thinking in terms of a “duality” is a misconception.turbo-1 said:Einstein is often cited as the man who killed the aether and established the particle nature of photons, but this is in direct opposition to the views he expressed in his later published works. (see link above)
Yes, and Schroedinger (the man who came up with the wavefunction which bears his name) was opposed to any idea of “collapse” of the wavefunction :turbo-1 said:Hubble is often cited as the man who proved the reality of the Big Bang (cosmological expansion extrapolated back to a point source) although he publicly resisted and /or seriously doubted that explanation until the end of his life.
"If we have to go on with these damned quantum jumps, then I'm sorry that I ever got involved."
Erwin Schroedinger
Both Einstein & Schroedinger were deeply dissatisfied with the notion of “wave-particle duality” and “collapse of the wavefunction”. Here is an extract from a letter sent by Albert to Erwin :
"You are the only person with whom I am actually willing to come to terms. Almost all the other fellows do not look from the facts to the theory but from the theory to the facts; they cannot extricate themselves from a once accepted conceptual net, but only flop about in it in a grotesque way."
It’s time that wave-particle duality was consigned to the dustbin, where it belongs.
MF
Yes, I am suggesting that. And I think I have a good reason to make that claim. The redshifted photons are lazy, but still get here.moving finger said:Hi Chronos
I agree re tired light, however I am not sure that I understand your comment "Photons from a z=2 supernova are only half as energetic as those from a z=1 supernova - but you receive twice as many of them due to time dilation effects."
You are not suggesting (I hope) that given two similar supernovae (A and B), one (A) at z=1 and the other (B) at z=2, we receive twice as many photons from B as we do from A?
MF
not sure we are talking about the same things.Chronos said:Yes, I am suggesting that. And I think I have a good reason to make that claim. The redshifted photons are lazy, but still get here.
Photons are unnecessarily obscuring things. A better analogy is in order: A Z=1 supernova shines at an intensity of say 100 watts per minute for 10 days [according to a Z=1 watch] before fading away. By the time the light gets to Z=0, the observer at Z=0 measures 50 watts per minute, but it shines for 20 days due to time dilation.moving finger said:not sure we are talking about the same things.
are you suggesting that there are twice as many photons (in total) arriving from the z=2 supernova when compared to the z=1 supernova?
MF
Huh? Light intensity falls off by an inverse square rule, so doubling the time of the light-curve falls WAY short of delivering equivalent energy.Chronos said:Photons are unnecessarily obscuring things. A better analogy is in order: A Z=1 supernova shines at an intensity of say 100 watts per minute for 10 days [according to a Z=1 watch] before fading away. By the time the light gets to Z=0, the observer at Z=0 measures 50 watts per minute, but it shines for 20 days due to time dilation.
The intensity is irrelevant. The wavelength of say sodium light from a Z=1 source is twice that of a Z=0 source, hence has only half the energy of the Z=0 emitter. The point is you receive those half-energy wavelengths for double the time it took the Z=1 source to emit them.turbo-1 said:Huh? Light intensity falls off by an inverse square rule, so doubling the time of the light-curve falls WAY short of delivering equivalent energy.
(sorry, please change that to watts, not "watts per minute" - watts is already a time-dependent unit, so 100 watts for 10 days then becomes 24kW hours, and 50 watts for 20 days is also 24kW hours)Chronos said:Photons are unnecessarily obscuring things. A better analogy is in order: A Z=1 supernova shines at an intensity of say 100 watts per minute for 10 days [according to a Z=1 watch] before fading away. By the time the light gets to Z=0, the observer at Z=0 measures 50 watts per minute, but it shines for 20 days due to time dilation.
Well, I would say 25kW hours [just being mathematically correct], but that aside, that is precisely what I am saying. There is no more missing energy than there is any missing time. Energy x Time works in every reference frame, in my opinion. I am attempting to eliminate the cowpies from the equation of state.moving finger said:(sorry, please change that to watts, not "watts per minute" - watts is already a time-dependent unit, so 100 watts for 10 days then becomes 24kW hours, and 50 watts for 20 days is also 24kW hours)
in which case... ok...nothing controversial in that...and... (getting back to your original suggestion)...what about the light from the Z=2 supernova (which at source should also emit 24kW hours)? Are you suggesting that we again should see (compensating for the distance dispersion) 24kW hours from this source?
MF
oh my... 100 watts times 24 hours per day times 10 days equals...Chronos said:Well, I would say 25kW hours [just being mathematically correct],
But the whole point is that there IS missing energy. The total energy flux (integrating over time) received from the z=2 SN is less than we would expect after correcting for the extra distance dispersion and based on the assumption that it is the same standard candle as the z=1 SN, and the amount by which it is less is actually (roughly) proportional to distance (Hubble's "law"). This is because the photons from the z=2 SN are more redshifted (have lower energy) than the z=2 SN, thus there is less energy per photon.Chronos said:but that aside, that is precisely what I am saying. There is no more missing energy than there is any missing time. Energy x Time works out in every reference frame, in my opinion.+
an illusion?Chronos said:I believe GR nicely accounts for the apparent missing energy as an illusion created by time dilation effects.
My understanding is that what you suggest does not agree with the experimental data.Chronos said:I am repeating my mantra, there is no missing energy... All the waves reach the destination, they merely take more time when forced to travel through stretched space. In the end, they all finish the journey. Would you agree energy density is time dependent?