06-15-2017, 10:26 AM | #21 |
Join Date: Feb 2005
Location: Berkeley, CA
|
Re: Effects of a different CMBR temperature?
It's when current generation stars form. First generation stars formed at higher temperatures, but you're not going to get planetary systems around first generation stars.
|
06-15-2017, 10:42 AM | #22 |
Join Date: Aug 2007
|
Re: Effects of a different CMBR temperature?
In addition, planets around first generation stars would be hydrogen and helium only.
__________________
Fred Brackin |
06-15-2017, 11:58 AM | #23 | |
Join Date: Jun 2005
Location: Lawrence, KS
|
Re: Effects of a different CMBR temperature?
Quote:
__________________
Bill Stoddard I don't think we're in Oz any more. |
|
06-16-2017, 10:47 AM | #24 |
Join Date: Jun 2005
Location: Lawrence, KS
|
Re: Effects of a different CMBR temperature?
So, okay, on one hand, mean energy per unit volume varies as L^(-4). On the other hand, minimum mass for gravitational collapse to form a solar system varies as T^(3/2). To link the two, we need a conversion between energy and temperature.
* In basic thermo, temperature was defined as mean molecular kinetic energy, which would suggest that T is proportional to E, probably using Boltzmann's constant or the ideal gas constant. * In blackbody radiation, energy radiated per unit time is proportional to T^4. * However, the universe doesn't seem to be radiating into anything other than itself. I believe the proportionality for energy *content* in a medium is that internal radiation is proportional to T^3. Which of these gives the right scaling relationship?
__________________
Bill Stoddard I don't think we're in Oz any more. |
06-16-2017, 11:21 AM | #25 |
Join Date: Jan 2005
Location: Gothenburg, Sweden
|
Re: Effects of a different CMBR temperature?
The first stars formed when the universe was about 200 million years after the Big Bang. How hot would the CMB be then.
__________________
“When you arise in the morning think of what a privilege it is to be alive, to think, to enjoy, to love ...” Marcus Aurelius |
Tags |
cmbr, space, spaceships, worldbuilding |
|
|