Space is currently at approximately NEGATIVE 270 Celsius. The last time that the general temperature of the universe was zero Celsius it was probably some short (cosmologically speaking) time after the Big Bang and consisted of some sort of hypothetical gluon/plasma/quark/condensate. All matter as humans understand it is gone in a practical instant.
this post was submitted on 15 Dec 2023
4 points (100.0% liked)
ELI5
65 readers
1 users here now
Explain it to me like I am 5. Everybody should know what this is about.
founded 2 years ago
Are you trying to say that all matter was in its building block shape when the general temperature was 0 celsius?
And when that material touches us, we'd become same stuff and stopped existing as we are now (evaporate).
Don't take my opinions too seriously, I'm just referencing my Astronomy notes (of which come from a single semester of a single class). With that said, here's my 2¢ guess:
I think they're trying to say that the last time the universe as a whole was 0°C, was probably before the formation of matter in the universe (I'll guess the inflation era, just after the birth of the universe, somewhere 10^(-35 to -33) seconds).
At this point in the universe, atoms cannot form (as the nuclear forces binding atoms are overwhelmed by the gravitational forces of all the energy in the Universe — you ever crush a cracker? It'd probably be like that). Perhaps even sub-atomic particles (protons, neutrons, etc.) can't form. All that's there is sub-sub-atomic particles (which we don't know much about, from my understanding).
So basically we (and the world, etc.) would be ripped apart at the sub-sub-atomic level by the immense forces (gravitational, etc. — remember, all of the matter/energy in the universe is being concentrated in a small place) of the early universe.
So, it's not that we would necessarily evaporate, nor that touching sub-sub-atomic matter would kill us, but more-so that we'd be crushed, at the sub-sub-atomic level, by the gravitational forces of the early universe. It'd probably be painless though, at least.
Space wasn't 0 Kelvin (I'm assuming you mean "absolute zero" because outer space is currently colder than 0°C/32°F) at any point in the past. In fact, the farther you go back in time, the warmer the universe gets, on average. This is because the same amount of energy was packed closer together when the universe was smaller. As the universe got bigger and things moved farther apart, the average temperature got colder.
As for what would happen if we magically teleported ourselves back to when the universe was very young, we would be cooked from all the radiation that was flying around, or if we went really far back, we'd just be blown apart because the entire universe was a hot plasma.
Space wasn’t 0 Kelvin
I think you also misread my question/thread title 😁
In fact, the farther you go back in time, the warmer the universe gets, on average.
I know this. Space was Planck temperature in the first very short time when it was born. After that it started cooling down.
I tried to go back in history with my question.
.
As for what would happen if we magically teleported ourselves back to when the universe was very young, we would be cooked from all the radiation that was flying around
Okay, so at the general space temperature of 0 celsius the radiation was still too crazy for us to survive?
0 Celsius? Space is far colder than that. Did you mean 0 Kelvin?
We would all be very dead very fast. At 0 Kelvin the fundamental atomic particles have no motion. The heat of the earth primarily comes from our sun, and without that the geothermal heat would not be nearly enough to keep us warm and alive before the magma under the crust itself cooled off.
In ELI5 terms - space is colder than ice or even snow. It’s so cold that it would even freeze lava! Without our sun, the earth would get so cold that everyone and everything on it would turn to ice.
I meant 0 celsius.
So we'd need to go THAT FAR back to history in our "mind game" where the most space in, well, "empty space", was 0 celsius.