Effects of a different CMBR temperature?

[malloyd]

Originally Posted by vicky_molokh

IOW, even if you raise it to 30K or even 100K, this will have zero noticeable effect on planetary climates?

Well for terrestrial planets. It may matter for iceballs. It's much the same issue as the second stars of binary systems usually don't matter for the habitable planet's temperature.

Two temperature sources add as the fourth root of the sum of their fourth power. So if you have two sources that would heat something to 100K in isolation, their combination heats the thing to 119K, which could matter, but if you have a one source that heats it to 300K and add another that would heat it to 100K, the combination heats it to 300.9K, which is likely negligible.

Edit: Is there a goal here? If you want a setting where space happens to be warm, I wouldn't suggest tampering with cosmology. Look for an excuse to bathe the entire region of the setting in a hot gas cloud instead. Yeah it's a little tricky to justify why whatever heated a cloud light-years across didn't kill everything in the region, but you can probably come up with something. If another galaxy collided with the Milky Way you might be able to get a jet of gas getting tossed off in the direction of one of the Magellanic Clouds that would still be fairly warm when it got there with less handwaving than changing the expansion of the universe. Sure it'll pass through, or cool back down again in 10 or 100 million years, but your metaplot doesn't need that much time anyway, right?

[Anthony]

Originally Posted by vicky_molokh

IOW, even if you raise it to 30K or even 100K, this will have zero noticeable effect on planetary climates?

30K may prevent the formation of planetary systems; 100K almost certainly will. Upper limit for having planets that support life is probably a CMBR temperature of 6-8K due to age of the universe effects. However, if somehow we teleport a planetary system into a location with a different CMBR, a 100K background would increase the temperature of a habitable planet by about 1.5 degrees kelvin.

Originally Posted by vicky_molokh

Will it have any effect on the 'space is very cold' factor of detection under any circumstances (such as ways of radiating away waste energy in an adjusted spectrum, perhaps with some ultra-tech advancements)? Or none either?

If it's high enough it will cause increased background noise, but for the most part thermal emissions will be at wavelengths where the CMBR is dim. If your goal is to make detection in space harder, I wouldn't mess with the CMBR, just increase zodiacal dust by a lot. Or add an asteroid belt (blowing up Mars and/or Venus would accomplish both objectives).

[Anthony]

Originally Posted by vicky_molokh

Greetings, all!

I'm curious: what would be the implication of a setting having the Cosmic Microwave Background Radiation temperature higher than in ours?

Well, the temperature of the CMB is directly related to the expansion of the universe, so you can just look at what the universe looked like when it was younger. If you don't want a younger universe you probably have to change dark energy or something.

Originally Posted by vicky_molokh

Currently I'm mostly see differences in calculating blackbody temperatures of everything, and in detection modifiers for objects in space, but what would those changes be, based on a given new value of the temperature?

Unless you're scanning at microwave wavelengths, changes in the CMB will not directly affect detection at all. However, differences in the expansion of the universe probably mean there's also changes in the backgrounds of galaxies, which will have some effect.

[Phantasm]

Seems like there would be some changes on the cosmic scale of things with galaxy clusters being closer to each other, but...

Very few changes in the mundane minutia that most games would happen in. At most, you'd see faster intergalactic travel, but since most of that happens at the speed of plot anyway....