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  #21  
Old 20-11-2008, 07:23 PM
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Gravity does not Suck

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Well you are new here so your are not going to know what folk think about me being stupid if you talk a lot... and I do ...the numbers tell you that you if you think about it....somewhere and often I must put my foot in it....so the point is its not a personal thing....I understand how people could see it that way... but it is nice that you do not regard me so...thank you.... and keep at those equations so you can explain it all to me... do plenty of problems ..so I am told by someone who knows more than me.

alex
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  #22  
Old 20-11-2008, 10:41 PM
Karls48 (Karl)
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Bojan wrote-“Photon is stable and does not decay. We can detect it even if it is coming from near the edge of the visible Universe.
What is happening, thought, wavelength is changed (it becomes longer) because of expansion of the universe (similar to Doppler effect), so the photons from the edge of the visible Universe would have wavelengths infinitely long (frequency would have been zero, energy also zero).”

Is no this just fancy way to say that the photon decayed to nothing? By this definition it would become DC current with zero voltage. Where did the original energy it had go to? What happen to the law of conservation of energy?
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  #23  
Old 21-11-2008, 09:28 AM
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Quote:
Originally Posted by Karls48 View Post
Bojan wrote-“Photon is stable and does not decay. We can detect it even if it is coming from near the edge of the visible Universe.
What is happening, thought, wavelength is changed (it becomes longer) because of expansion of the universe (similar to Doppler effect), so the photons from the edge of the visible Universe would have wavelengths infinitely long (frequency would have been zero, energy also zero).”

Is no this just fancy way to say that the photon decayed to nothing? By this definition it would become DC current with zero voltage. Where did the original energy it had go to? What happen to the law of conservation of energy?
I expected someone will ask this question this problem was bugging me since long time ago, but I do not know the answer.

But, the potential energy of the Universe increases with expansion. Perhaps this is where energy from "stretched" photons go to.

EDIT:
BTW, Universe expansion itself has to be accountable for energy conservation. I think I read somewhere long time ago that potential energy of the Universe exactly balances the mass contained within Universe... It seems I have to do some more searching and reading on this subject.

Last edited by bojan; 21-11-2008 at 09:45 AM.
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  #24  
Old 21-11-2008, 09:44 AM
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Gravity does not Suck

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The answer is simple......there is no such thing a wave with and infinite wave length... it makes no sence... and wave with and infinte wave length is a line... there can be no wave.... so lets work on something less than infinite... a wave lenght of 500 trillion light years to the power of 3000... now although that is a very long wave is is not infinite in fact it is still infinitely removed from that length...

When dealing with finite inputs you can not get a result producing an infinity... you can not double finite to reach infinity nor can you halve infinity to come to a finite...

There must always remain a wave if the sums say otherwise they need adjustment.

alex
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  #25  
Old 21-11-2008, 09:49 AM
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Sorry to be brief but the batteries are flat and I can only run when the panels are running and really charging the lap top almost direct..
gotta go clouds coming
alex
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  #26  
Old 21-11-2008, 10:07 AM
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Alex,mathematically, "infinite wavelength" is perfectly correct thing to say.
Especially if we start with some (short) wavelength which becomes longer as expansion progresses.
Photons arriving from the exact edge of the visible Universe will be DC...
Photons that arrive from a bit closer distance will have finite (but very long) wavelength.

Are you familiar with math term called "limes"? (or limit, I believe this is English term)
You have to get accustomed to mathematical way of thinking

BTW, this why we are talking about the "edge of the visible Universe" because we can not see anything at or beyond this (mathematical) boundary.

Last edited by bojan; 21-11-2008 at 10:41 AM.
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  #27  
Old 21-11-2008, 11:07 AM
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Quote:
Originally Posted by Karls48 View Post
Bojan wrote-“Photon is stable and does not decay. We can detect it even if it is coming from near the edge of the visible Universe.
What is happening, thought, wavelength is changed (it becomes longer) because of expansion of the universe (similar to Doppler effect), so the photons from the edge of the visible Universe would have wavelengths infinitely long (frequency would have been zero, energy also zero).”
Is no this just fancy way to say that the photon decayed to nothing? By this definition it would become DC current with zero voltage. Where did the original energy it had go to? What happen to the law of conservation of energy?
It's a good question. And there is a simple answer. The laws of physics such as the conservation of energy apply within frames of references not across them. In the photon's frame of reference (if it can be called that), the photon doesn't lose energy, as much as it doesn't lose energy in the observer's frame. The observer in his cosmological frame of reference only sees the photon of a particular frequency and doesn't see a change of the photon's energy in his frame. Energy is therefore conserved in both frames.

Consider relative velocities. Each observer will measure a different velocity in their frame of reference and therefore calculate a different kinetic energy. For kinetic energy to be conserved across frames would imply a baseline common to all the observers (an absolute frame of reference) which of course doesn't exist.

Regards

Steven
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  #28  
Old 21-11-2008, 11:55 AM
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Bojan thanks for that.
Steven thanks for your explaination.

Bojan I know what you are saying.

Calculus the math of limits.

We never get to where we are going because we are alwayas still half way from our destination... and that is the math yes...but we can get where we are going and even move past it... but yes I get the point.

I gather the edge of the observable Universe is where light cant get past in the sense that we are moving away from it faster than light due to the expansion... the light beyond the observable boundary simply can not catch us...math will tell us it is going backwards if we let it...but an interesting proposition really.

AND as if this were not perplexing enough Stevens explaination has me wondering... I think I get it but then ... I realise dont know zip.

Thinking about this raises another thought ... if there is a point where expansion is faster than light..the edge I expect... how do we "see" that.. I see our part in effect moving away from another part of the Universe but between those parts we have a reccession of c or greater??? Sorry just being cheeky the Sun is out but I am still cabin crazy:l ol:.

I think I better call someone and say I am sorry and I will agree that men are responsible for all wrongs on the planet me mainly


alex
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  #29  
Old 21-11-2008, 12:30 PM
Karls48 (Karl)
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Bojan, I also think of disappearing energy of photon as becoming potential energy. It got one problem, thought. In our environment the conversions of potential and kinetic energy takes place all the time. To recover the photons and the information it carries (in this scenario) would require (to my way of thinking) reversing the direction of time flow. That leads to the interesting speculations about the fate of the Universe and about what may exist beyond the observable Univers.
This kind of inconsistencies pops up all the time when you consider one section of the current Cosmology and compare it to other sections. In some other tread you wrote that it is necessary to accept current view of mainstream science. And to large extent I agree. What irritates me is that by large the mainstream theoretical science presents its model of universe as definitive and only possible truth, instead of saying – based on our current knowledge and our abilities that’s how we thing the universe works.
From historical point of view it is quite possible that couple thousand years from now the GR, Space-Time and limit on speed will have about same credibility as flat earth idea.
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  #30  
Old 21-11-2008, 05:56 PM
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The great thing about the net is if you look long enough you can find someone of good repute who says what you want to hear........
a quote from wiki on page

http://en.wikipedia.org/wiki/Particle-wave_duality
.............
The path integral formulation or sum over histories approach of Richard Feynman also considers particles to be the primary entities:

I want to emphasize that light comes in this form—particles. It is very important to know that light behaves like particles, especially for those of you who have gone to school, where you were probably told something about light behaving like waves. I'm telling you the way it does behave—like particles. [Emphasis as in the original]

—Richard Feynman, QED: The Strange Theory of Light and Matter (1985), p. 15
Feynman goes on to explain that the wave behaviour is exhibited only as a consequence of how the particle histories are summed. He says:

It's rather interesting to note that electrons looked like particles at first, and their wavish character was later discovered. On the other hand, apart from Newton making a mistake and thinking that light was "corpuscular," light looked like waves at first, and its characteristics as a particle were discovered later. In fact, both objects behave somewhat like waves, and somewhat like particles. In order to save ourselves from inventing new words such as "wavicles," we have chosen to call these objects "particles," but we all know that they obey these rules for drawing and combining arrows [representing complex values of wave functions] that I have been explaining. It appears that all the "particles" in Nature—quarks, gluons, neutrinos, and so forth (which will be discussed in the next lecture)—behave in this quantum mechanical way. [Emphasis as in the original]...

So what does this leave us with a particle scribing a wave thru space and eventuality "flat lining"...

I spent all afternoon reading about light and duality again and so I thought this was amusing... I wonder in the context of what he said how he would explain the double slit experiemnt..I guess he has someplace... I will look.


alex
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  #31  
Old 21-11-2008, 06:33 PM
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Quote:
Originally Posted by sjastro View Post
It's a good question. And there is a simple answer. The laws of physics such as the conservation of energy apply within frames of references not across them. In the photon's frame of reference (if it can be called that), the photon doesn't lose energy, as much as it doesn't lose energy in the observer's frame. The observer in his cosmological frame of reference only sees the photon of a particular frequency and doesn't see a change of the photon's energy in his frame. Energy is therefore conserved in both frames.

Consider relative velocities. Each observer will measure a different velocity in their frame of reference and therefore calculate a different kinetic energy. For kinetic energy to be conserved across frames would imply a baseline common to all the observers (an absolute frame of reference) which of course doesn't exist.

Regards

Steven
Steven, thanks for this explanation, it sounds plausible to me :-)
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