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[Physltest] Re: [Phys-L] Re: Basic Facts About Dark Energy



The trouble is that you are trying to explain a bad verbalization
of a compllcated concept. The word "energy" crept into "dark energy" by
analogy. If the observations had shown deceleration, that could have been
explained by an "excess" of mass-energy in the universe. Acceleration
seems like anti-gravity, so by analogy the publicizers looked for language
relating the observation to mass-energy. Be brave! Find your own
language to explain what is going on without using the word "energy".




On Mon, 10 Jan 2005 STRatliff@NWC.EDU wrote:

Regarding Dark Energy:

Remember, that all of these statements were prefaced by, "If dark energy
exists, it has the following properties."

1. I can change "It exists uniformly throughout the universe" to "It
exists throughout the universe."
Perhaps the main problem here is that it is not required to be uniform?
If it exists throughout the observable universe then it probably exists
throughout the universe.

2. New version: It makes up most of the energy of the observable
universe.

3. My intent with statement number 3 was to somehow explain, in simple
terms, that there is a fundamental difference between "dark energy" and,
for example, light energy or sound energy. You can build a photocell that
will directly detect light. You can build a microphone that detects sound
energy. We don't have a dark energy detector. Perhaps it would be
preferable to say that we don't have a dark energy sensor.

4. My intent with statement 4 was to explain in simple terms the idea
that dark energy, if it exists, is causing the expansion of the universe
to accelerate. As a further note, I think that when we say that the
universe is expanding, we really mean that space itself is expanding.

Any further comments?

Thank you for your help.

Sincerely,
Steven Ratliff


Steven T. Ratliff
Institutional Researcher / Professor of Physics
Northwestern College
3003 Snelling Ave. N.
St. Paul, MN 55113-1598
U. S. A.

Internet: stratliff@nwc.edu



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