NASA

After the New Year I sent this letter to NASA:

Hi NASA.

So, I just read this blog post:
http://kottke.org/15/02/current-paradoxes-in-cosmology

Which took me to this blog post:
https://medium.com/the-physics-arxiv-blog/the-paradoxes-that-threaten-to-tear-modern-cosmology-apart-d334a7fcfdb6

They describe this paradox:

“What’s more, there is an energy associated with any given volume of the universe. If that volume increases, the inescapable conclusion is that this energy must increase as well. And yet physicists generally think that energy creation is forbidden.”

Here’s my Question: Why does increased VOLUME necessarily mean increased ENERGY when that VOLUME is a vacuum. Can’t the energy and matter just be spreading across the universe through a vacuum without altering total ENERGY?  Like marbles across a floor?

Thank you,
Chad

A few weeks later NASA replied thus:

The answer is that it is the energy density that is constant, so as the volume increases, there must be more energy. The constant energy density seems to be an observed feature of the Universe – that is, it is needed to explain the observed expansion in a simple way compatible with General Relativity. Here is a more detailed explanation:
http://www.preposterousuniverse.com/blog/2013/11/16/why-does-dark-energy-make-the-universe-accelerate/

You might also enjoy reading a related post:
http://www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved/

Here is a good site for anyone interested in astronomy:
http://antwrp.gsfc.nasa.gov/apod/astropix.html

Brian and Jeff
for Ask an Astrophysicist

Editorial. I’m still unsure what’s going on. I need to find me an astrophysicist in the flesh.

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2 Comments

Filed under Ephemeron

2 responses to “NASA

  1. From the second link: “In the case of dark energy, that evolution is pretty simple: the density of vacuum energy in empty space is absolute constant, even as the volume of a region of space (comoving along with galaxies and other particles) grows as the universe expands. So the total energy, density times volume, goes up.”

    That explained it for me.

    • OK, I think I get this part. This is WHAT happens to density/energy. I just can’t imagine HOW it happens. It seems like making something out of nothing.

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