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Post by carnyx on Dec 14, 2010 11:39:26 GMT 1
@sta#43
You have stated the problem right there;
..there and then, of course.
There may well be other suppositions, but this one holds sway at this time, a supposition ... which is inherently impossible to prove. And also whether yea or nay has no actual consequence, save in a metaphysical sense .. (and also a financial sense of course.)
And the orthodoxy of the community of cosmologists ( a binding ... or 'religious' belief) is based on a supposition that says that the universe is expanding.
Now, if you-all could give us, the laymen, (who fund the activity of the brotherhood via the big stick of state power) .. a set of examples of what this actually means ... then there could be some wider communion of the spirit as it were.
But of course that is impossible, because the brethren would be open to judgement, and could even lose the leverage on the funding!
So, STA, in the spirit of open understanding, here is a problem for you to solve;
- Given the Hubble Constant , and assuming it applies to the expansion of ALL matter at ALL scales.. even down to the atomic level;
- How much would a body the size of the Earth have expanded in, say 4 billion years?
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Post by speakertoanimals on Dec 14, 2010 13:02:40 GMT 1
Nope, a testable hypothesis. We can study the light from distant objects, and given that the emission and absorption lines in the spectrum relate to the exact atomic energy levels, we can extract information as to what the atomic physics of the elements is like on that distant object. No, it is based on data that clearly indicates not just that the universe is expanding, but more importantly, that the speed of recession varies with distance. Its the details that matter! How to explain that pattern in the data, that is the question, and the best explanation we have so far, which is in accord with the parts of general relativity that we can test closer to home, is that the universe is expanding. First point is that given the physics, we wouldn't expect atoms to expand, since the assumptions used to derive the unform expansion model don't apply at that scale. Second, as regards the solar system, the calculation has been performed: xxx.lanl.gov/PS_cache/astro-ph/pdf/9803/9803097v1.pdf and if we include the universal expansion, the effects on the orbits of the planets over the lifetime of the solar system is (in terms of acceleration) 44 orders of magnitude smaller than the effect of the sun. In terms of orbital period, the natural variation in the moons orbit is 22 orders of magnitude larger than predicted variation due to expansion. Fractional change in radius of orbit over lifetime of the solar system is 10^-24. So, for the earth, with orbital radius of about 1.5 x 10^11 m, that makes a difference of 10^-13 m (or about a hundreth of the radius of a hydrogen atom over the lifetime of the solar system). You seem to be assuming that cosmology is ALL speculation, that cosmologists just make up pretty stoires based on their own prejudice, and never go near any data. Which is plain rubbish!
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Post by carnyx on Dec 14, 2010 14:10:54 GMT 1
STA, thanks for your answer.
It seems that the cosmologists have established to their own satisfaction that the expansion of the universe is, in a real sense, so tiny that it is almost immeasureable even at the scale of the orbital radius of the earth!
And when you put some scale to these things, the wondrousness disappears .. to the point where the real wonder is why grown adults concern themselves with such trivialities, and more importantly why they should be subsidised-via-force by the rest of the populace!
An expense of other people's spirit on 'angels-on-pins' estimations?
This is not to say that such essentially recreational activities are to be decried, just that they should not be publically funded to the point of making a kind of self-sustaining industry... which appears to rely on a supply of young undergraduates, like a pyramid scheme. Anyway, I also think that nickcosmosonde has a point (on another thread ) about the religiose nature of cosmology, with his;
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Post by speakertoanimals on Dec 14, 2010 14:21:36 GMT 1
Because some people are too stupid to realise how very SMALL the earth is compared to the rest of the universe!
Trivialities? Only to the irremediable dense and stupid. And thankfully not that many people seem to agree with you................
Let's take a very, very simple question. Why is the sky dark? Far from trivial, and the epxanding universe, with a finite past and the red-shift of the CMB is one way to answer that. Of course, if you're just content to lo0ok down at the mud, then so be it, but why try to mock those with a little broader vision that yours?
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Post by carnyx on Dec 14, 2010 14:57:54 GMT 1
STA,
I see you are attempting to invoke the metaphysical power of cosmology, rather than the actualité, via a kind of 'de haut en bas' technique.
In fact, reversing your position ... your quantification of the expansion of the universe shows how SMALL the effect is ... literally insignificant ... in human terms.
And whilst it is nice to have a cosmologically broad vision, why do you feel that cosmologists ought to be subsidised?
Should poets be state employees, too?
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Post by speakertoanimals on Dec 14, 2010 17:45:39 GMT 1
Because unlike some people, I feel that more ought to come into the equation that just 'does it make money'.................
Of course, the point is that the general public is actually rather interested in cosmology -- such TV programs always get a good audience, as do programs about dinosaurs, archaeology etc. The general public does seem rather proud of such famous cosmologists as Stephen Hawking, and there does seem to be a general feeling that such research is a good thing, and should be supported.
The point (rather than just picking on subject areas that you personally happen to consider daft or unscientific or pointless) is what is academia and universities FOR. Research that can earm money, in a very straightforward way, will often be funded directly by those who wish to make money out of it. The issue is then what about the rest of it -- cosmology, other bits of science that you might consider daft, astronomy (what use is that to anyone eh!), or even the arts.........
And frankly, I really don't want to get into such a pointless with someone with so little knowledge as yourself. It will just end up as -- harrumph, harrumph, don't see why MY taxes should be spent on such rubbish.
Whereas others, some of whom work in universities, can see a point to learning beyond the purely monetary. And think it is somewhat sad that others can't........................
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Post by carnyx on Dec 15, 2010 0:26:14 GMT 1
@sta
You miss the point. It is not that the activity of cosmology makes or does not make money .. or that it needs to be a paid or an unpaid occupation. It is a command-economy question of the kind that existed in communist regimes; should cosmology be state-funded? and if so why shouldn't poets be on a par with cosmologists?
The problem with state funding is that the money is exacted from the average person via the big-stick power of the state, from which there is no appeal. The second problem is that we are also compelled to put up with whatever cosmology dishes up, yet we have do a choice with poetry ...
I see you allude to the entertainment value of cosmology as part of the justification.. therefore why not apply for funding from the BBC? .. which is in turn also dependent on coerced funding; but at least there is a choice of sorts .. unlike the output from Universities.
Frankly you will have to thank the climatologists for this general disaffection with University Scientists, as grant-seeking behaviour seems to take priority over truth-seeeking.
But, as students now have to pay a proportion of the costs, one wonders how many cosmology courses will run next year..
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Post by Progenitor A on Dec 15, 2010 9:47:32 GMT 1
@sta You miss the point. It is not that the activity of cosmology makes or does not make money .. or that it needs to be a paid or an unpaid occupation. It is a command-economy question of the kind that existed in communist regimes; should cosmology be state-funded? and if so why shouldn't poets be on a par with cosmologists? The problem with state funding is that the money is exacted from the average person via the big-stick power of the state, from which there is no appeal. The second problem is that we are also compelled to put up with whatever cosmology dishes up, yet we have do a choice with poetry ... I see you allude to the entertainment value of cosmology as part of the justification.. therefore why not apply for funding from the BBC? .. which is in turn also dependent on coerced funding; but at least there is a choice of sorts .. unlike the output from Universities. Frankly you will have to thank the climatologists for this general disaffection with University Scientists, as grant-seeking behaviour seems to take priority over truth-seeeking. But, as students now have to pay a proportion of the costs, one wonders how many cosmology courses will run next year.. In summary: We have established that the velocity of light is not a constant? We have established that light is accelerated (positively or negatively) by gravity)? We have established that light undergoes infinite accelerations and decelerations without any loss or gain of energy? We have established that in black holes (according to cosmologists) light is decelerated so much that it never escapes? We have established (from observation of black holes) that light is reduced to zero velocity from our point of view? We have established that light is not affected by em, electric or magnetic fields? We have established that space is not a vacuum(and cosmologists tell us that space is seething with energy fluctuations and furthermore that 90 % of space consists of dark matter) so we have never had a vaccum throgh which light travels.? Therefore it seems that the conservation of energy laws are flouted by light, and if the speed of light is constant in vacuo then that postulation is unverifiable? We have established that the velocity of light is relative? Not much light on this subject then
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Post by speakertoanimals on Dec 15, 2010 14:08:24 GMT 1
Wrong. the velocity of light in vacuo is a constant, it can be slower in matter.
Wrong. The speed of light is not changed, the direction may be -- hence positive or negative does not apply (that would be, in common parlance, an increase or decrease in speed).
Wrong. The speed of light is unchanged, but path can be bent by gravity, and looses energy/changes frequency due to gravitational redshift or blueshift.
Wrong. It isn't deceleration for starters.
Wrong. Our point of view doesn't make sense, all we can ever define as a measure of speed is the speed measured by someone who is in the vicinity, and for them, the speed of light is still c.
Almost right. Em fields couple to charges and currents (classically), and photons are not charged, hence no effect. Which is why different frequencies of light can pass by each other and have no effect.
There is a small, predicted higher-order scattering of light by light, a purely quantum effect, but you'd need a gargantuan em field to see it!
Space is pretty much a vacuum. The CMB is what I think you thought cosmologists refer to, but since that is just photons, see above. Their are quantum vacuum fluctuations, but those are, in effect, the source of the higher-order light scattering lightb effects I referred to above.
For all practical purposes, lilght travelling through intergalactic space is as close as light in vacuum as anyone would like.
Wrong (almost). The speed of light is constant stuff HAS been verified, here on earth. Simple experiment -- get a particle to emit light, measure the speed. Chuck the same particle in an accelerator, whizz it up to as close to light speed as you can get, let it emit light again, and measure the velocity of that. Comes out the same.
The conservation of energy is a bit tricky when we have gravity, but for light, it is realy no more mysterious than the fact that if you throw a ball in the air, it looses kinetic energy. A photon does the same except its kinetic energy is given by frequency/momentum NOT speed. Hence speed stays the same, but frequency changes, to give loss of kinetic energy.
I make that 0.5 out of 8, must try harder...............
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Post by StuartG on May 6, 2011 0:22:09 GMT 1
The speed of light is 299 792 458 m/s [exact], I thought You all needed to know this. in vacuo that is....
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Post by buckleymanor1 on May 6, 2011 0:34:23 GMT 1
Ok so the speed remains the same how does this reconcile with light which travells through a prism. The light which comes out blue is at a different speed to the light which is red. Is gravitational redshift or blueshift in anyway different and if it is how.
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Post by StuartG on May 6, 2011 2:10:20 GMT 1
As I understand it, when em travel through different media they have their velocity reduced. The media can be classed by their velocity ratio VR. When the light emerges from the prism it is split into its component frequencies (colours). The light emerging will speed up again because the VR of air/atmosphere has a VR nearer 1. Again, as I understand it a range of Ultra High Frequencies can be treated in a similar way, using a wax prism [and similar focussing with wax lens]. Cheers, StuartG
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Post by buckleymanor1 on May 6, 2011 12:13:03 GMT 1
As I understand it, when em travel through different media they have their velocity reduced. The media can be classed by their velocity ratio VR. When the light emerges from the prism it is split into its component frequencies (colours). The light emerging will speed up again because the VR of air/atmosphere has a VR nearer 1. Again, as I understand it a range of Ultra High Frequencies can be treated in a similar way, using a wax prism [and similar focussing with wax lens]. Cheers, StuartG This sounds right, though the continuity don't.The light is split within the prism into colours and slows but it's still coloured when it exits.I am not sure that red light or any of the spectral light will differ in velocity in or out of the prism it looks the same how do you show it is not.(if it looks like a duck) If you were to place a second prism along side the first the light that exits would be white which could be traveling at c which makes more sense. Can you refer to an experiment that shows that spectral light within the prism travels at a different velocity than the spectral light which exits.
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Post by StuartG on May 6, 2011 13:47:09 GMT 1
I don't move in scientific circles, so to find experimental data will be slow. First note my previous frivolous but true statement with the added proviso of 'in vacuo' this suggests that light velocity is different for other media. However if light is considered an em, then extrapolation from the simple co-axial cable with one of its parameters of VF [velocity factor], usually in the region 0.8 - 0.5, does help to illustrate that this change in velocity can be measured in that case. A further reference can be seen here en.wikipedia.org/wiki/Refractive_index where it says "The velocity at which light travels in vacuum is a physical constant, and the fastest speed at which energy or information can be transferred. However, light travels slower through any given material, or medium, that is not vacuum." further it goes onto explain that "As light exits a medium, such as air, water, or glass, it may also change its propagation direction in proportion to the refractive index " and further justifies by saying "Refractive index of materials varies with the frequency of radiated light. This results in a slightly different refractive index for each color" not an experiment, I agree, but a 'text book' statement. Cheers, StuartG ps. A further reference can be found here en.wikipedia.org/wiki/Optical_fiber#Index_of_refraction where it's discussing 'optic fibre' and says "The index of refraction is a way of measuring the speed of light in a material. Light travels fastest in a vacuum, such as outer space."
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Post by buckleymanor1 on May 6, 2011 15:12:07 GMT 1
Thanks for the links.What I am finding difficulty with is that when you see red light it is because that is the frequency at which it proper gates.Why should it differ in speed in air or glass.The fact that before white light enters the prism it is at c and then is refracted by the glass once it enters and its frequency changes to be broken into different colours which travel at different speeds.When it exits it is still red if its speed or velocity had changed why has it's frequency remained the same in other words it is not white light exiting you still see it as red.
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