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Post by eamonnshute on Dec 11, 2010 12:09:51 GMT 1
carnyx,
If you divide 10Km by 1 million you get 1cm, not 1Km.
I have answered your question. To repeat, the only thing that affects the speed of light is the refractive index of the medium, which for space is virtually 1. The distance travelled etc. are irrelevant.
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Post by carnyx on Dec 11, 2010 12:39:08 GMT 1
How many centimetres in a metre?I suggest you redo the sums.
And dealing with just the interaction with matter;
- How about the density of the intergalactic filaments?
- And all those hydrogen atomds that are supposed to spontaneously appear/disappear?
- And what about all that missing 'dark matter'?...
Then, you have not even mentioned the effect of magnetic, electric fields on light?
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Post by carnyx on Dec 11, 2010 15:37:57 GMT 1
@nm#27
To narrow the field to cosmology which like climatology and sociology is purely speculative; I think that religious attitudes do come into it.
To the average person, cosmology is an amusing pastime, and fills the same kind of cultural niche as eskimos do with their 'cats cradle' game, which stretches ingenuity.
But to some social inadequates, like Dawkins for example, it is a means of gaining social power but without having to exercise any responsibility, via their parading of unprovable clevernesses, and the coining of new metaphysical 'bubbles'.
They also tend to exhibit the vice of Bacon's schoolmen, who were in a real sense presumptious, or otherwise seeking 'laws' to explain behaviours rather than induction based on observation.
So, we see these professional meta-scientists behaving with the kind of intolerance fond in extreme sectarian religions such as calvinism. That they are state-funded is a glaring anachronism, and ought really to be stopped.
Whilst they can be spotted a mile away by any normal person, I think the best test for them is to give us their definition of what they mean by 'truth'.
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Post by Progenitor A on Dec 11, 2010 16:22:12 GMT 1
@nm#27 To narrow the field to cosmology which like climatology and sociology is purely speculative; I think that religious attitudes do come into it. To the average person, cosmology is an amusing pastime, and fills the same kind of cultural niche as eskimos do with their 'cats cradle' game, which stretches ingenuity. But to some social inadequates, like Dawkins for example, it is a means of gaining social power but without having to exercise any responsibility, via their parading of unprovable clevernesses, and the coining of new metaphysical 'bubbles'. They also tend to exhibit the vice of Bacon's schoolmen, who were in a real sense presumptious, or otherwise seeking 'laws' to explain behaviours rather than induction based on observation. So, we see these professional meta-scientists behaving with the kind of intolerance fond in extreme sectarian religions such as calvinism. That they are state-funded is a glaring anachronism, and ought really to be stopped. Whilst they can be spotted a mile away by any normal person, I think the best test for them is to give us their definition of what they mean by 'truth'. ;D What a polemic! Love it! |
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Post by Progenitor A on Dec 11, 2010 16:27:41 GMT 1
The speed of light depends on the density of the medium, not how far it has travelled, or anything else. I know thatI am splitting hairs here Eammon, but density is a function of space (volume) and hence the ditance travelled is relevant ro density. When light enters water it immediately slows down, but then continues at the same reduced speed. The density of matter in space is negligible, so the effect on the speed is also negligible. But 'negigible' quantities , if they are ignored can lead to enormously important consequences, errors that are absurd when repeated and repeated, and there is nowt more repetitive than the universe. |
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Post by eamonnshute on Dec 11, 2010 16:40:38 GMT 1
But 'negigible' quantities , if they are ignored can lead to enormously important consequences, errors that are absurd when repeated and repeated, and there is nowt more repetitive than the universe. "Can" does not mean the same as "always does". The density of matter in the universe has a negligible effect on the speed of light, or even on the time it takes to reach us. It is as simple as that. Matter equivalent to Carnyx's monster diamond will only delay light by a tiny fraction of a second! |
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Post by carnyx on Dec 11, 2010 18:06:08 GMT 1
eammon,
~40% reduction in light speed through diamond is pretty impressive. And 1Okm of diamond is a likely amount of mass that this stream of photons will physically interact with.
But what about the effect on this light of passing through the considerable number of gravity and electric and magnetic fields? Will these photons have been accelerated/decelerated/deflected/refracted/reflected, even?
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Post by eamonnshute on Dec 11, 2010 18:37:06 GMT 1
eammon, ~40% reduction in light speed through diamond is pretty impressive. And 1Okm of diamond is a likely amount of mass that this stream of photons will physically interact with. But what about the effect on this light of passing through the considerable number of gravity and electric and magnetic fields? Will these photons have been accelerated/decelerated/deflected/refracted/reflected, even? Light emerging from the diamond will still have the same speed and frequency as before it encountered it. Light is deflected slightly by gravity near galaxies, but not by electric or magnetic fields. The frequency would not be affected either. If there was simple explanation of cosmic redshift other than the expansion of the universe don't you think that someone would have thought about it by now? |
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Post by carnyx on Dec 11, 2010 19:02:19 GMT 1
Are you quite sure of that?
and re redshift ... in fact there are credible alternative explanations which of course you know, but Eammon if you REALLY want to deal in certainties ... looking at the history of science it is CERTAIN that inflation will be replaced as an explanation.
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Post by speakertoanimals on Dec 12, 2010 19:20:41 GMT 1
First off , inflation is NOT the same as expansion.
Second, this line that science progresses, hence it is highly likely that in the future we''l realise it is all crap is a very weak line of argument.
Progress will still leave us with the measurements we do have, and no matter how hard we try, explanations which have been tried and failed will very likely still fail.
So, just bringing in gravity (or electric or magnetic fields) ignores the fact that we do know what effect those have on light, and it is NOT the same as a universal redshift. That's the point, to get the universal shift of frequency that we do see, at all frequencies, we can't invoke matter (which treats different frequencies differently), or gravity (what we gain on the fall down, we loose again on the way back up). All that does fit the bill is the expansion of space, which then has the merit that it agrees with observations of basic redshift, AND agrees with other observations such as the redshift of the decay curves for distant supernovae.
Well just shows that the average person (based on yourself I presume), knows very little science of cosmology if they think that cosmology is PURELY speculative. Plus I think you have some very weord ideas if you think Dawkins cares that much about cosmology, given that he worked in evolutionary biology, and probably knows very little cosmology.
Cosmology -- we have a WEALTH of observations (a little thing callaed astronomy), plus a wealth of observations here from on earth as to the way that matter behaves. Making all taht fit in ANY way is far from trivial.
Calling it purely speculative is the height of ignorance, as are these feeble attempts to claim that there are other supportable explanations for red shift other than the usual cosmological one. Not just flogging a dead horse, but a dead, buried, decomposed and turned back into compost and used for growing your roses ex-horse.............
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Post by speakertoanimals on Dec 12, 2010 19:23:57 GMT 1
Plus claiming that distance travelled has anything to do with DENSITY just shows a total ignorance of the very basics. Akin to: distance travelled involves length, density involves volume (which is length cubed) therefore density involves distance travelled.........
WRONG! If anything, distance travelled (if you were a trawl net) would involve total mass collected, just in terms of total mass on journey would be distance travelled times area of mouth of net, multiplied by collecting efficiency. But since none of that applies to light, its just the dimensionally-inept trying to encourage the ignorant..............
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Post by Progenitor A on Dec 12, 2010 19:50:04 GMT 1
First off , inflation is NOT the same as expansion. Second, this line that science progresses, hence it is highly likely that in the future we''l realise it is all crap is a very weak line of argument. Progress will still leave us with the measurements we do have, and no matter how hard we try, explanations which have been tried and failed will very likely still fail. So, just bringing in gravity (or electric or magnetic fields) ignores the fact that we do know what effect those have on light, and it is NOT the same as a universal redshift. That's the point, to get the universal shift of frequency that we do see, at all frequencies, we can't invoke matter (which treats different frequencies differently), or gravity (what we gain on the fall down, we loose again on the way back up). All that does fit the bill is the expansion of space, which then has the merit that it agrees with observations of basic redshift, AND agrees with other observations such as the redshift of the decay curves for distant supernovae. Well just shows that the average person (based on yourself I presume), knows very little science of cosmology if they think that cosmology is PURELY speculative. Plus I think you have some very weord ideas if you think Dawkins cares that much about cosmology, given that he worked in evolutionary biology, and probably knows very little cosmology. Cosmology -- we have a WEALTH of observations (a little thing callaed astronomy), plus a wealth of observations here from on earth as to the way that matter behaves. Making all taht fit in ANY way is far from trivial. Calling it purely speculative is the height of ignorance, as are these feeble attempts to claim that there are other supportable explanations for red shift other than the usual cosmological one. Not just flogging a dead horse, but a dead, buried, decomposed and turned back into compost and used for growing your roses ex-horse............. Good heveans! She is back! This person is self-evidently semi-literate in that she find extreme difficulty in constructing grammatical sentences She is also innumerate Here she is demonstrating innumeracy More nonsense, in that you are mistakenly trying to equate a velocity defined in terms of ds/dt, with a different distance, which is wavelength. Your wavelength is s per hertz is really rather odd, as is frequency is d(phi)/dt, since you've not bothered to define phi................... In short, your usual bollocks! This is an absolute demonstartion of ignorance of mathematics and simple equations of motion The woman is innumerate, yet still she bounces back with her 'arguments' based on insult which she hopes will shut people up! Madam, you are a waste of time! |
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Post by carnyx on Dec 12, 2010 20:30:54 GMT 1
@sta
From this I see that your Cosmology is now attempting to subsume all of Physics, Astronomy, Chemistry and presumable Mathematics, too!
Face it, STA; your covetous discipline is no more than a Cosmogony (with Bell's on, you might say !) ..
The evidence that you practice a kind of Latter-Day Astrology; a religiose metaphysics; is found in your frequent asperities when faced with the threat that the science is most definitely not settled.
As for my open-ended speculative questions, they are NOT 'attempts to claim' as you put it, because unlike you I am not trying to prove anything ...
However, I will say that your kind of Cosmology is not a fit subject for public funding. Rather, it should be reserved for consenting adults in privatem as it fills a private emotional need, as does any religion, that seeks a Grand Unified Explanation.
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Post by speakertoanimals on Dec 13, 2010 12:18:12 GMT 1
O do stop being so SILLY!
It is blindingly obvious that when we are trying to understand the behaviour of distance objects, or what might have happened to the light from those objects on its way to us, that we have to refer back to the way matter behaves here on earth.
For starters, when we look at the spectrum of a distance object, what do we see? We see spectral lines in the same PATTERN as for spectral lines we might investigate on earth, but with the entire pattern red-shifted. Hence we suppose that:
1) Matter in distance objects behaves in the same way as matter here on earth, that the hydrogen that exists here behaves in the same way as hydrogen that existed there.
2) The systematic difference is then explained (the universal red-shift, that applies to ALL frequencies) in terms of the expansion of space.
If you think you can do cosmology (or even astronomy) without referring to physics and chemistry here on earth, then you are even more ignorant that I suspected.................
So far, your 'arguments' just reduce to -- cosmology is obviously just a load of nonsensical speculation, and we shouldn't waste good money on it. Which is just based in plain ole ignorance of what cosmology actually is, and what the evidence for it is.
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Post by nickcosmosonde on Dec 14, 2010 3:24:02 GMT 1
Very interesting point. Firstly, the effects of gravity on light is not within SR's province, strictly speaking, but GR's. But the invariance of c still applies. The apparent speed of light is c, to us or anyone else who measures it, however they're moving relative to its source. We will not be able to measure it until it reaches us, of course. So this "slowing down of c from our point of view" is not apparent. It's a deductive inference we make based on our theoretical understanding of the way mass curves spacetime - observed in for example the Eddington 1919 eclipse measurements.
From our frame of reference it has not slowed down, no. I am aware that this judgement is in contradistinction to a lot of writers on these matters - including Hawking in his Brief History, amazingly enough - but I think this is merely an indication of how difficult it is to get these counterintuitive theoretical predictions clear in our minds. SR in particular is impossible to understand - if anyone claims they do, don't believe them. They might think they do, but the fact of the matter is it's internally contradictory, and simply can't be understood due to this inherent logical paradox. The only way to comprehend it is to see it as an incomplete and self-contradictory preliminary stepping stone to GR. To see it as Lorentz's theory, in other words. I'm fairly sure this is how Einstein came to see it.
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