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.

Re: Effects of a different CMBR temperature?
 

In addition, planets around first generation stars would be hydrogen and helium only.

Re: Effects of a different CMBR temperature?
 

It wasn't molten platinum, if I remember my freshman physics correctly. It was a hollow cavity inside a solid block of platinum. You need it to be a hollow cavity to make the effects of albedo irrelevant. Checking Halliday and Resnick, I see they say it also makes the size and shape of the cavity irrelevant.

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?

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.