Semi-OT: A General Tech Question Thread for me :)

Renegade 13 · #1 September 30th, 2005, 12:02 PM

Quote:

dogscoff said:
When the universe was born, it was all hydrogen- there were no heavy elements.

As far as I know, when the universe was born, it was essentially an electrically charged soup of particles. Free atomic nuclei and free electrons were everywhere, since the temperature for a few hundred million years was far too hot to allow electrons to 'permanently' bond with the free atomic nuclei. So for quite a while in there it was an electromagnetically opaque universe, until things cooled off enough to allow the first elements to form.

narf poit chez BOOM · #2 September 30th, 2005, 01:28 PM

...Why would all of those elements be hydrogen?

Wolfman77 · #3 September 30th, 2005, 01:35 PM

Protons atract electrons. 1 proton + one electron = hydrogen. Protons, having the same electric charge, need to be forced together to form larger atoms. Which happened only after stars formed.

narf poit chez BOOM · #4 September 30th, 2005, 01:59 PM

That makes sense.

But...Wouldn't 1 proton + 1 electron = neutron?

Wolfman77 · #5 September 30th, 2005, 02:40 PM

Sort of, if you force them together, they could create a neutron and some energy, I think. There is something that keeps them from doing that on their own, can't remember what it is off the top of my head, and need to go do some work for a half hour or so, I'll look it up when I get back here. Or you can try wikipedia if you want.

Suicide Junkie · #6 September 30th, 2005, 03:09 PM

Quote:

Wolfman77 said:
Sort of, if you force them together, they could create a neutron and some energy, I think. There is something that keeps them from doing that on their own, can't remember what it is off the top of my head, and need to go do some work for a half hour or so, I'll look it up when I get back here. Or you can try wikipedia if you want.

You don't get energy out. You have to put energy in.

Free neutrons have a half-life of 11 minutes, and decay back to a Proton and Electron.

Neutrinos get thrown around too, but I don't think you care.

Wolfman77 · #7 September 30th, 2005, 04:51 PM

Sorry, I had it backwards. That's what I get for being in a hurry and not looking it up first.

Hunpecked · #8 September 30th, 2005, 03:02 PM

According a Wikipedia article, right after the Big Bang there was about 74% hydrogen-1, 1% hydrogen-2, 25% helium-4, and trace amounts of lithium and beryllium. Nucleosynthesis stopped there because there are no stable 8-nucleon elements (2 x helium-4) and there was insufficient time for many triple-alpha collisions (3 x helium-4).

http://en.wikipedia.org/wiki/Big_Bang_nucleosynthesis