From: Robert J. Bradbury (bradbury@aeiveos.com)
Date: Tue Jan 07 2003 - 18:55:23 MST
On Tue, 7 Jan 2003 ABlainey@aol.com wrote:
> Forgive my ignorance, But isn't 7000K pretty damn hot by our standard, That
> being small squishy water based lifeforms. Or am I mistaken? I assume 7000k =
> 7000kelvin or 6700 ish C, or does the K stand for another astronomical
> measurement of temperature that I am not familiar with?
It took me a long time to figure out what the astronomers meant by this.
It turns out its a measure of the degree of ionization of the atoms floating
around in space. It takes a lot of energy for example to strip of 5-9 electrons
from an iron atom (very high temps). If the electrons are pushed far enough
away, they cannot be recaptured and the iron atom remains ionized. If the
atom happens to bump into an atom with a lower temperature, its going to
strip off its electrons, effectively leaving that atom at a higher temperature.
And so it goes.
> If I am right in my assumption, then wouldn't that kind of heat caused
> problems for any out of solar system travel we have in the future?
It depends on the density of the highly ionized (high temp) atoms.
As Spike, Amara and I have previously discussed this varies a lot
depending on where you are (in the local bubble, I think its like
0.001 atoms/cu cm). In high density regions if you are traveling
at high velocity you do need an ablation shield to absorb the
impacts of these ions.
> or is the
> relatively low density of heated atoms insufficient to cause significant
> problems.
In the bubbles it seems to be a minor annoyance -- but it depends in
large part on how fast you are going.
> Could the heat be collected and used as a power source for a vehicle?
> I'm thinking something along the line of heat to laser light, bounced of a
> light sail.
I haven't run across that idea before -- I expect the conversion
efficiencies and/or energy harvesting efficiencies would be pretty low.
Robert
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