Originally posted by lemon limeSorry to be slow to reply. I'll read your earlier posts and form a reply in the next hour or two.
So basically you think you understand what I've been saying. It is obvious though that you don't.
But no worries, we've covered this topic before... and this is why I was specifically asking DeepThought about it.
Originally posted by lemon limeHi lemon lime,
A question about redshift. Why does redshift occurring in relation to earth necessarily mean everything is accelerating away from everything else? If earth itself is in motion relative to some other more or less central point of observation then it might only appear the entire universe is accelerating. If it turns out the earth is simply decelerati ...[text shortened]... g this out here as something to think about... I doubt if it can be proven one way or the other.
the previous responses to that question were inaccurate. There is no reason that a distant galaxy should not be moving towards the Earth. I can't remember the exact figure, but the Solar System is moving at a speed of the order of 150 km/s compared with the microwave background. So all the observations need to be corrected for that. In any given galactic cluster the galaxies are all moving in different directions from one another. Andromeda is moving towards us. However at a given distance the average redshift is what matters. The basic assumption is that on average any given cluster has as many galaxies moving one way as another.
In terms of your analogy, you're right if there is only one car. However, if there is a roadful of them then some other cars will be accelerating and some cars will have constant speed. The average speed of all the cars is what the observer on the train should be observing.
Your underlying point about what would be seen from another fairly distant galaxy is a good one. I think that, in general, there is no reason to believe that the universe would look any different from another location. It's a fundamental assumption in cosmology which I assume, but do not know, had been tested as far as one can. The problem is that we can measure radial velocity quite easily, but not tangential velocity at those distances. So it is rather difficult to prove isotropy.
Science has it's limitations, but the theory is more-or-less consistent with observation, so it's scientifically true, which means "provides a reasonable description and not yet disproven".
Originally posted by DeepThoughtThanks for replying. The analogy was a simple one because the focus of my questions and comments have to do with redshift. Unless I'm mistaken, whether or not redshift is observed is entirely dependant on where the observer is and in what direction the observer is moving.
Hi lemon lime,
the previous responses to that question were inaccurate. There is no reason that a distant galaxy should not be moving towards the Earth. I can't remember the exact figure, but the Solar System is moving at a speed of the order of 150 km/s compared with the microwave background. So all the observations need to be corrected for that. ...[text shortened]... it's scientifically true, which means "provides a reasonable description and not yet disproven".
It has always fascinated me how light will always appear to be traveling at the same constant speed 'c' regardless of where the observer is, or in what direction or speed the observer is moving.
But I'm curious to know how we are able to determine the difference between light traveling between two objects accelerating away from one another, and two objects moving apart but not accelerating. It seems to me we should be seeing a redshift in both of those circumstances... if so, are there different degrees (or wavelengths) of observable redshift?
Originally posted by lemon limeRight, I missed that aspect. There are two issues, one is expansion, the other is that the expansion is accelerating. One can legitimately infer that the universe is expanding from redshift alone. The acceleration in the expansion was inferred from observations of Type Ia supernovae. These are standard candles, they cannot happen if the mass of the progenitor white dwarf is less than the Chandrasekhar limit, this means that they always have the same luminosity [1]. In an accelerating universe the light from these supernovae has to travel further for the same redshift as in a non-accelerating universe and so appear too faint. The Wikipedia article about this explains it reasonably well and gives other supporting evidence [2].
Thanks for replying. The analogy was a simple one because the focus of my questions and comments have to do with redshift. Unless I'm mistaken, whether or not redshift is observed is entirely dependant on where the observer is and in what direction the observer is moving.
It has always fascinated me how light will always appear to be traveling at the s ...[text shortened]... ose circumstances... if so, are there different degrees (or wavelengths) of observable redshift?
[1] It used to be believed that they never measurably exceeded the Chandresekhar limit either. Recently someone pointed out that if two white dwarves collided the result would be a super-luminous Type Ia supernova. This isn't a problem for the above argument as it would produce an error in the wrong direction (it would tend to make us think that the universe was decelerating).
[2] https://en.wikipedia.org/wiki/Accelerating_universe
Originally posted by DeepThoughtBesides, two white dwarf's colliding would be a statistical anomaly, that would happen, what, maybe one in a million cases? If so, the averages would win out.
Right, I missed that aspect. There are two issues, one is expansion, the other is that the expansion is accelerating. One can legitimately infer that the universe is expanding from redshift alone. The acceleration in the expansion was inferred from observations of Type Ia supernovae. These are standard candles, they cannot happen if the mass of the p ...[text shortened]... nk that the universe was decelerating).
[2] https://en.wikipedia.org/wiki/Accelerating_universe
Originally posted by lemon limeWhat are you thinking the consequences are if your thinking is right?
Thanks for replying. The analogy was a simple one because the focus of my questions and comments have to do with redshift. Unless I'm mistaken, whether or not redshift is observed is entirely dependant on where the observer is and in what direction the observer is moving.
It has always fascinated me how light will always appear to be traveling at the s ...[text shortened]... ose circumstances... if so, are there different degrees (or wavelengths) of observable redshift?
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Originally posted by DeepThoughtThere is more to the theory of evolution than just biological evolution that depends on abiogenesis which violates the Law of Biogenesis.
I hate to spoil the party, but the theory of evolution does not depend on the Big Bang theory. It depends only on the Earth having a history longer than about 500 million years. What is more the observed redshift of distant galaxies compared with standard candles, along with the microwave background, is rather hard to explain without a big bang. Wheth ...[text shortened]... reation ab nihilo or some prior universe there is no reason to doubt the overall picture.
1. Cosmic Evolution: The origin of time, space and matter, by the Big Bang
2. Chemical Evolution: The origin of higher elements from hydrogen.
3. Stellar and Planetary Evolution: The origin of stars and planets.
4. Organic Evolution: The origin of Life.
5. Macro-Evolution: The changing from one kind of species to another kind of species.
6. Micro-Evolution: The variation within kinds of species.
Big Bang Cosmology is a Fake
Originally posted by RJHindsR.J., the Theory of Evolution is the one proposed by Darwin. It does not include explanations of where the world came from and does not include abiogenesis. The theory was called evolution because of the general meaning of the word evolution. Systems exhibit change in time, so we say that they evolve. This does not mean that every system that evolves in some way is part of the theory of evolution. So your post has failed to muddy the waters.
There is more to the theory of evolution than just biological evolution that depends on abiogenesis which violates the Law of Biogenesis.
1. Cosmic Evolution: The origin of time, space and matter, by the Big Bang
2. Chemical Evolution: The origin of higher elements from hydrogen.
3. Stellar and Planetary Evolution: The origin of stars and planets ...[text shortened]... tion within kinds of species.
Big Bang Cosmology is a Fake
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Originally posted by DeepThoughtActually it was EVIL-Lution that Darwin suggested. That has already been disproved. You can continue to live in ignorace if you wish for I can only lead a horse to water since I can't make it drank.
R.J., the Theory of Evolution is the one proposed by Darwin. It does not include explanations of where the world came from and does not include abiogenesis. The theory was called evolution because of the general meaning of the word evolution. Systems exhibit change in time, so we say that they evolve. This does not mean that every system that evolves in some way is part of the theory of evolution. So your post has failed to muddy the waters.
Originally posted by RJHindsDisproved by whom? None of the stuff you seem to regard as evidence has the slightest credibility. Really, I've got no problem with people having religious beliefs, but don't confuse the spiritual with the material, you're on to a loser that way.
Actually it was EVIL-Lution that Darwin suggested. That has already been disproved. You can continue to live in ignorace if you wish for I can only lead a horse to water since I can't make it drank.
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