Spacetime: Stretching or Growing? Or

  • Thread starter salvestrom
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  • #26
I'm not at all sure an atom having a larger radius means it emits light with a longer wavelength. Even if it did - and there's some evidence the bohr radius was slightly bigger in the passed, I have no idea if it was ever big enough to explain expansion in terms of matter contraction. In fact, an electron would need a higher energy to be at a further distance in a larger atom. while it would emit light it would surely be of shorter wavelegth. this whole idea of matter contraction just doesn't have any relevancy to observed physics.
A larger atom is the same thing as observing it closer: all it's constituents will be (appear) larger, strings, quarks, orbitals, wavelength. It's just a matter of scale. (by larger atom here, I do not mean uranium vs hydrogen, I mean identical but larger).
Just imagine a diagram of an atom emitting a light at some wavelength, then enlarge the whole diagram.

Or just imagine the photon travelling from a far away galaxy, eventually reaching our galaxy which in the meantime has shrunk, making us see a redshifted photon.
 
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  • #27
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A larger atom is the same thing as observing it closer: all it's constituents will be (appear) larger, strings, quarks, orbitals, wavelength. It's just a matter of scale. (by larger atom here, I do not mean uranium vs hydrogen, I mean identical but larger).
Just imagine a diagram of an atom emitting a light at some wavelength, then enlarge the whole diagram.

Or just imagine the photon travelling from a far away galaxy, eventually reaching our galaxy which in the meantime has shrunk, making us see a redshifted photon.
http://perrybw.wordpress.com/2011/1...n-of-matter-vs-the-metric-expansion-of-space/

the above is the first link found when googling "matter contraction". while he isn't a crank and fully acknowledges that he's just musing. I hope you have something stronger to actually back up your statements.
 
  • #28
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alphachaptml "I find it is more natural to consider such a comoving volume as dimensionnaly fixed, which also means we have to consider its content (galaxies and atoms) as shrinking."

There are vague analogies you can make between a universe that began with particles in fixed positions 'relatively' inertial WRT each other but with matter particles shrinking and a universe with particles simultaneously expanding away from each other and remaining constant in size. The analogy has fewer problems at close range but at any credible cosmological distances it doesn't just break down, it implodes.

Galaxies extrapolated to positions where they would be at any z 'time' show a relatively uniform density around the observable universe, simply closer together as z increases. The distances galaxies appear to be away from us is a direct concequence of how long they had to get away from us until the light we are seeing arrived. As a result the images Hubble Telescope presents of near and far distant galaxies are enormously different in size.

The shrinking Universe needs to posit that the galaxies are the same distance apart at any point in time and that that distance isn't changing. The problem is not just that this model presents galaxies as not visually appearing much further away with larger z-distant galaxies but neglects the obvious point that the furthest galaxies have barely begun to shrink. They should be enormous in this model-relative to their 'relatively' closer position in space than the expanding universe model.

mathal
 
  • #29
alphachaptml "I find it is more natural to consider such a comoving volume as dimensionnaly fixed, which also means we have to consider its content (galaxies and atoms) as shrinking."

There are vague analogies you can make between a universe that began with particles in fixed positions 'relatively' inertial WRT each other but with matter particles shrinking and a universe with particles simultaneously expanding away from each other and remaining constant in size. The analogy has fewer problems at close range but at any credible cosmological distances it doesn't just break down, it implodes.

Galaxies extrapolated to positions where they would be at any z 'time' show a relatively uniform density around the observable universe, simply closer together as z increases. The distances galaxies appear to be away from us is a direct concequence of how long they had to get away from us until the light we are seeing arrived. As a result the images Hubble Telescope presents of near and far distant galaxies are enormously different in size.

The shrinking Universe needs to posit that the galaxies are the same distance apart at any point in time and that that distance isn't changing. The problem is not just that this model presents galaxies as not visually appearing much further away with larger z-distant galaxies but neglects the obvious point that the furthest galaxies have barely begun to shrink. They should be enormous in this model-relative to their 'relatively' closer position in space than the expanding universe model.

mathal
Interesting point.
I think this effect was already observed and measured.

Angular size redshift relation
an object ... beyond a certain redshift (roughly z=1.5), appears larger on the sky
http://en.wikipedia.org/wiki/Angular_diameter_distance#Angular_size_redshift_relation
http://en.wikipedia.org/wiki/Distance_measures_(cosmology [Broken])

But I don't know are secure the experimental evidences are in this respect.
We don't know of many high redshift galaxies, and we can't see them very well.

The furthest known galaxies have redshift factor z of 8, 9 or 10.
Those galaxies are barely detectable, and we don't really know their size or shape.
http://cosmiclog.msnbc.msn.com/_news/2011/01/26/5920882-hubble-spots-farthest-galaxy-again [Broken]
http://firstgalaxies.org/

At a redshift factor z=9,
- space expansion viewpoint:
the universe was 10 times smaller, so those galaxies should be packed more densely, and appear larger cause of the angular size redshift relation.
- matter contraction viewpoint:
the galaxies were 10 times larger, so they should appear larger, and so would look more densely packed.

Concerning this, it looks like both viewpoints have identical observational consequences.

If the ancient universe was smaller, should it not visually be stretched across the celestial sphere to fill it, making ancient galaxies appear larger?
(basically this is angular size redshift relation, cited earlier)
 
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  • #30
71
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Interesting point.
I think this effect was already observed and measured.

Angular size redshift relation
an object ... beyond a certain redshift (roughly z=1.5), appears larger on the sky
http://en.wikipedia.org/wiki/Angular_diameter_distance#Angular_size_redshift_relation
http://en.wikipedia.org/wiki/Distance_measures_(cosmology [Broken])

But I don't know are secure the experimental evidences are in this respect.
We don't know of many high redshift galaxies, and we can't see them very well.

The furthest known galaxies have redshift factor z of 8, 9 or 10.
Those galaxies are barely detectable, and we don't really know their size or shape.
http://cosmiclog.msnbc.msn.com/_news/2011/01/26/5920882-hubble-spots-farthest-galaxy-again [Broken]
http://firstgalaxies.org/

At a redshift factor z=9,
- space expansion viewpoint:
the universe was 10 times smaller, so those galaxies should be packed more densely, and appear larger cause of the angular size redshift relation.
- matter contraction viewpoint:
the galaxies were 10 times larger, so they should appear larger, and so would look more densely packed.

Concerning this, it looks like both viewpoints have identical observational consequences.

If the ancient universe was smaller, should it not visually be stretched across the celestial sphere to fill it, making ancient galaxies appear larger?
(basically this is angular size redshift relation, cited earlier)
I get your point, the angular size isn't the problem I suspected that it would be. You can get to the same scenario either way. How would the model handle the acceleration of the expansion-(accelerated shrinking in this model)?

mathal
 
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