Expanding Universe

**MOHANTHILAGARAJ** · December 19th, 2011, 04:12 AM

Does the distance between celestial bodies within a solar system change due to expanding universe? Does distance between earth and mars change over a period of time?

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**Strange** · December 19th, 2011, 04:35 AM

No, the expansion only happens at very large scales. So the solar system, galaxies and even galaxy clusters are not part of the expansion. You can think of them as being gravitationally bound and overcoming the expansion because of that.

**MOHANTHILAGARAJ** · December 19th, 2011, 04:46 AM

Originally Posted by Strange

No, the expansion only happens at very large scales. So the solar system, galaxies and even galaxy clusters are not part of the expansion. You can think of them as being gravitationally bound and overcoming the expansion because of that.

Oh ok ok. Thanks! I was wondering if it affects solar system then over the period of time, the distance between sun and earth will change (increase I assume). As a consequence, the temperature of earth will change. As there will be no impact on solar system so no question of my concern

**Jack1941** · December 30th, 2011, 10:46 PM

The expanding universe was proposed to explain the red shift in light. It is now know that other influences effect the red shift. They need to shelve the expanding universe concept.

**MeteorWayne** · December 30th, 2011, 11:24 PM

Not really. It's all the other "explanations" that have been shelved.

**SpeedFreek** · December 31st, 2011, 09:02 AM

Originally Posted by Jack1941

The expanding universe was proposed to explain the red shift in light. It is now know that other influences effect the red shift. They need to shelve the expanding universe concept.

When all other known influences that can cause redshift have been accounted for, what we are left with is a huge amount of cosmological time-dilation, caused by the expansion of the universe. In a high redshift galaxy, only the tiniest amount of that redshift (<1%) can be due to either peculiar motion or a difference in gravitational potential (the other main causes of spectral shift).

There is currently no known effect that could causes such a large redshift in distant galaxies, apart from the expansion of the universe. So, Jack, you need to shelve the concept that there are alternatives that can otherwise explain that redshift, at least until we find some!