[Airbreaker (OP)]

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[Airbreaker (OP)]

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You know that the universe is expanding, well does that mean as the planets expand and move further away, eventually we (planet Earth) will be left on it's own.

[syhprum]

The expansion of space is only apparent between bodies that are so far appart that there is no gravitational effect.
We will still have our companion galaxies in the local group

[neilep]

Eventually though....long long long after Earth is over and done with there will eventually be nothing...this is...as long as the expansion continues....all that will be in the sky (that can bee seen)....will be black .........and then......if the theories are to be borne true that space itself will eventually rip itself apart.....http://en.wikipedia.org/wiki/Big_Rip

[Eagle333]

But then you have the concept of dark matter. So as this expansion takes place, dark matter fills the void. But if understanding your question, yes,  but we still have our companions. Maybe the universe expands, but not the individual solar systems....

[turnipsock]

The universe could be shrinking for all we know. Andromeda is already coming towards us at 300,000m/s and it's the closest galaxy to the milky way. Due to the light taking so long to reach us, from galaxys that are far away, all we see is the universe still expanding. I could be that they are now hurtling towards us at alarming speed.

[DoctorBeaver]

The universe could be shrinking for all we know. Andromeda is already coming towards us at 300,000m/s and it's the closest galaxy to the milky way. Due to the light taking so long to reach us, from galaxys that are far away, all we see is the universe still expanding. I could be that they are now hurtling towards us at alarming speed.

If the universe were shrinking, we would not see galaxies moving away from us. That we do see them moving away is indicative of the universe expanding.

[Saganist]

Hi guys,

This website really impressed me and may help this thread's discussion?

http://www.atlasoftheuniverse.com/ [nofollow]

Cheers.

PH

[Dick1038]

All that we can say is that the universe is expanding at the present time.  Measurements show that the expansion was slower in the distant past.  Einstein's theory states that the universe is either expanding or contracting. So, an oscillating universe is theoretically possible.

Dark matter can't be filling the void as the expansion continues. DM represents energy and so cannot be created from nothing.  Unless there is some strange physics that converts dark energy into dark matter.  Perhaps most or all of the DE will be converted to DM eventually and so gravity may pull things back together again.

By the way, why doesn't energy have gravity.  Matter and energy are two forms of the same thing.  One has gravity and one doesn't.  Hmmm.  Where does the gravity go when matter is converted to energy. If DM pervades the universe, perhaps its "gravity" accounts for the observed red-shift.

Please pardon my ramblings.

[syhprum]

Energy in as much as it is a different form of mass does indeed exert gravity.

[Dick1038]

If energy does indeed exert gravity and if dark energy pervades intergalactic space and gravity can red-shift light, then the observed red-shift of the light from galaxies may not be entirely from cosmic expansion.  So, the universe may not be as large as assumed.

Since energy can't be created to fill in the expansion, then the energy density of space must be decreasing.  Thus the repulsive effect of dark energy must be decreasing.  But this contradicts the measured acceleration of the expansion. Can this conflict be reconciled?