Love it when it snows

to what did the universe expand from? I never studied astrophysics so I’m always fascinated by the subject so I’m being sincere here. What do astrophysicists teach in regards to before the bang.

I recommend you read Stephen Hawking's A Brief History of Time. If you're in Redmond I'll lend you mine. Its actually pretty easy going until the end where he's explaining how matter can escape from a black hole.

The answer to your question, what they teach, is conditions prior to the Big Bang are undefined. This is because as we run the calculations back further and further the closer we get to time zero the greater the density of energy. 

Not matter. Energy. Einstein showed energy equals mass times the speed of light squared. E=mc2. Go back far enough, it was pure energy. Matter only formed some moment after time zero.

You can look up the details. I've long since forgotten. As you would know if the mods in their infinite wisdom hadn't decided to remove the post, this was all stuff I learned in grade school. Well a lot of it anyway. More than you would believe.

So anyway yeah, undefined. 

Briefest of instants later, pure energy. Then matter. Which at first was almost exactly equal parts matter and anti-matter. Which they annihilate each other. Eventually this runs its course and turns out there's a bit more matter than anti-matter and so that's why its all matter now.

Would be cool if GK would vouch for this. Being theoretical physicist he should know, or at least be able to follow and understand. I am of course leaving out a lot of details, including even details I know about, never mind all the other cool stuff.

So the whole thing, all the matter there is, is expanding. You might well ask, expanding into what? Once again, undefined. But it can't be nothing. Nothing is literally "no thing", ie empty space. But there is no space. All the space there is is right here right now. Then too.

The universe you see is what we call finite and unbounded. Its finite because we can see and measure its size. But its unbounded because you can never find the end, let alone cross over into somewhere else. Its kind of like the Earth. Its finite. But you can travel all over round and round, forever, never able to leave. You can leave of course, but only by going up, into another dimension. Literally. Got it?

Okay so gonna post this, come back with more- cuz there's lots more.


 

Sorry, MC, I cannot vouch for that. 😛

With all of this navel gazing I found some lint.

Sorry, MC, I cannot vouch for that.

Not your area. I understand. Fascinated me since childhood. Oh well. Easy enough for people to look it up and see. If they don’t want to take my word for it. Which they shouldn’t. Even though its all crazy true.

to what did the universe expand from? I never studied astrophysics so I’m always fascinated by the subject so I’m being sincere here.

Okay so now we got all the matter there is, expanding out making all the space there is bigger and bigger. This is like hours, days, something like that (look it up) past the big one.

At which point - oh but wait, this is kinda cool. All that energy from the Big Bang? Its like a bell that’s been rung, its still slowly faintly ringing. Couple guys, Penzias and Wilson? whatever not gonna look it up their radio telescope had this noise and nothing they did would get rid of it, no matter which way they point the damn thing its there. Finally figure out its the remnant echo of the Big Bang. Won em a Nobel.

So anyway this all happened. Multiple lines of evidence.

Back to matter. Its almost all hydrogen. Because when the energy cooled and the matter formed it was electrons, protons, neutrons. They start pairing up and form hydrogen, one proton, one electron. Sometimes one neutron too. But usually one e, one p.

This hydrogen is all there is. Its expanding. Really fast. And hot. But cooling. Slowly cooling. And slowing down. Because, gravity. The mass of the cloud itself is trying to draw it all back together. (Remember this for later, happens again!) So its expanding, but slower and slower. To this very day.

Not uniformly. Some regions are a little more dense than others. What will later become local groups of galaxies separate out. Within those regions other clumps are drawn together by their mutual gravitational pull and will become galaxies. Same process happens within those and forms stars.

But not ours. Not yet. The first stars are super massive. The way stars work, the more massive the faster they burn through their hydrogen.

Now here’s where it gets interesting. Really freaking interesting. Because, think of it, there’s only hydrogen. Look around. Do you see any hydrogen? Ha! You see everything BUT hydrogen! Where’s all these other elements come from?

Good question. https://www.youtube.com/watch?v=ZJQjjBR6PbY

That’s right! When Carl Sagan said we are star stuff, he wasn’t just being poetic. We literally are.

Cliff Notes for those who won’t put in the hour to watch the (totally worth it) video: stars fuse hydrogen into helium. Really massive stars then keep on going using up the helium and in the process creating more elements. Eventually if the star is massive enough it goes supernova. The star collapses, and in this cataclysmic collapse the pressures and temperatures at the core of the star are so immense all the other elements on the periodic table are formed.

The release of all this energy then causes the star to explode, sending all these elements out into interstellar space.

So that when new stars form they have around them planets with all these elements. Elements like carbon. On which we are all based.

But seriously, watch the video. Coolest thing ever.

You misunderstand, MC. It is my area. I was being tactful. 🤗 I give you an A for enthusiasm, though.