Universal Expansion & Density

[polit]

Is the expansion of the universe causing quantum foam or the universe to become less dense? (or vice versa) I'm not asking which is the cause of which - I am asking if the universe or spacetime or quantum foam or whatever is becoming less dense due to/ causing the expansion of the universe?

[Ken G]

It seems to me the whole concept of "quantum foam" presupposes a theory that does not exist, to wit, a theory that marries gravity and quantum mechanics. Perhaps there are theorists who have an expectation about how such a theory should work, but I'd be pretty suspicious of any claims that are based on untested physics.

[polit]

Ok - I am going to research more about density of the universe & whatnot.

[George]

Is the expansion of the universe causing quantum foam or the universe to become less dense? (or vice versa) I'm not asking which is the cause of which - I am asking if the universe or spacetime or quantum foam or whatever is becoming less dense due to/ causing the expansion of the universe?

Assuming you are asking about normal matter density, as the universe expands in volume the net density will decrease. Galaxies and their associated clusters will not change much in density, though if the acceleration rate continues to increase, that might change things but not for a very long while.

[DrRocket]

Ok - I am going to research more about density of the universe & whatnot.

When you do that, stick to sources that quote well-established physics.

There is all sorts of stuff of a speculative nature involving "quantum foam", particularly writings on quantum loop gravity. There is also speculation like that from some string theory types. Neither quantum loop gravity nor string theory are established physics, despite a lot of publicity and hype.

Be very wary of recent popularizations. There is a tendency to present cutting-edge speculation as fact.