It's analogous to a combined count of how many people have commented on the post, or shared it (or "reblogged", to use the Tumblr term). It might also include likes? I only use Tumblr occasionally so I'm not sure.

I don't know why Tumblr counts things like this. I sort of like it though — it makes it feel like a distinct place. Tumblr hasn't escaped enshittification, but it makes me happy that it still exists as a little pocket of weirdos

That or a giant space turtle with elephants holding a flatten rock on it's back.

I'm skeptical of this. Life doesn't just need a certain temperature, it needs to convert lower entropy energy to higher entropy. A uniform environment temperature does not provide any usable energy. You would still need a star or some other energy source.

Well, "life as we know it". But for all we know energy rather than matter-based beings could have existed more readily back then, and perhaps struggle to exist now under lower density conditions. Thereby making that earlier era more habitable for their type of life, even as our current era is more habitable for our own type.

but it’s cool to imagine a universe where life was incredibly abundant

There was probably nothing but helium, hydrogen and a tiny bit of lithium at that period.

More weird to me is that, at some point before the first stars, the entire universe glowed through the entire rainbow, so there is a moment when, were you to travel back in time, the entire universe would glow blindingly green.

Interesting theory, I'd never heard of it before. All of the sudden, "a long time ago, in a galaxy far, far away", actually seems plausible (although this theory looks like it came well after SW in 2014).

The actual paper about it: https://lweb.cfa.harvard.edu/~loeb/habitable.pdf

Also its not true that space is "very very cold".

If you are in space wearing space suite that doesn't radiate heat properly, you could die from the excessive heat. Once dead your body stops producing heat and the existing heat eventually radiate away and your body freeze.

Space is neither hot or cold because these are property of matter. Since space has very little atoms, it technically has no temperature.

But you will if you sit in a vacuum for a while without a radiation source nearby, and it will be quite low.