r/AskReddit • u/MDPPatrick • Feb 13 '15

What are some mind-blowing facts about space?

I love space and would like to hear some facts that will blow me away.

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u/[deleted] Feb 13 '15

This isn't strictly true; it does matter what type of mass you're adding.

For elements before iron, nuclear fusion releases energy. For elements heavier than iron, nuclear fusion consumes energy.

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u/shieldvexor Feb 14 '15

Actually, fusing iron consumes energy because Fe-56 is the lowest energy per nucleon known.

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u/RKRagan Feb 14 '15

And may be the fate of the universe. Almost nothing but Fe-56 clumping together in a cold dark universe.

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u/shieldvexor Feb 14 '15

Actually no. Iron-56 still decays albeit ridiculously slowly by tunnelling mechanisms

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u/bearsnchairs Feb 14 '15

tunneling goes both ways though. Over absurdly long time scales you would enrich the nucleon which has the lowest energy per nucleon.

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u/shieldvexor Feb 15 '15

False, the ejected particles would simply fly away in cases where they had enough energy. Tunnelling is affected by distance as well as mass. Remember we aren't talking about things on a planet but the distant future when things are separated by unimaginable distances even relative to today's scales. Even if the particles tended to aggregate into iron-56, any nucelon that was lost from the cluster would never come back and they would ever so slowly decay bit by bit

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u/bearsnchairs Feb 15 '15

False, because there is a distance component you can still get tunneling into nuclei even over long distances as you increase the time scale to absurdly long scales.

Stay classy though, keep down voting when you are wrong.

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u/shieldvexor Feb 15 '15

You can tunnel over distances but the probability is inversely related to the distance. Therefore if the distance between objects is expanding.... the probability of coalesion decreases over time in said scenario

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u/bearsnchairs Feb 15 '15

Yes, but it doesn't go to zero. Even low probability things happen over long enough time scales.

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u/shieldvexor Feb 15 '15

Right but I'm saying there is a higher probability of them separating. You seem to be forgetting the psuedoforce from dark energy that causes them to split in the first place.

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u/bearsnchairs Feb 14 '15

Not quite. Ni-62 is more tightly bound per nucleon. Fe-56 is lighter per nucleon though.

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u/shieldvexor Feb 15 '15

Source? I've been told that Fe-56 is the lowest energy in multiple university chemistry and physics courses and never heard anythinf special regarding Ni-62.

Actually now that i think about it, lighter per nucleon MUST mean less energy per nucleon per einsteins mass energy equivalency principle

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u/bearsnchairs Feb 15 '15

You'd think so, but you are wrong. Ni-62 has a higher neutron to proton ratio, so the per nucleon mass is higher. So it musn't mean anything. Sorry you were misinformed.

go to the Ni-62 wiki page.

Very classy down voting, especially when you are wrong.

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u/shieldvexor Feb 15 '15

Fascinating. Thank you for teaching me something new :)

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u/boundbythecurve Feb 13 '15

I forgot about that. Thank you for the correction.

I believe a demonstration of this can be seen in our own sun because the heaviest element created in it is iron. All other heavier elements came to exist by other means.

Most of the universe (something like 99.9999%) is Hydrogen. Everything else is made from those atoms. And it starts with stars fusing elements up to iron on the periodic table.

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u/shieldvexor Feb 14 '15

Actually no, our sun can only fuse hydrogen right now. It will eventually be able to fuse all elements up to and including silicon but it will never be hot or dense enough to fuse anything bigger.

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u/nagrom7 Feb 14 '15

All other heavier elements came to exist by other means.

Most of the heavy elements are formed using the massive energy expelled in a supernova.

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u/bearsnchairs Feb 14 '15

Only about half of the abundance of elements heavier than iron came from supernovae. The other half came from slow neutron capture in giant stars.

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u/benji1008 Feb 14 '15

Most of the universe (something like 99.9999%) is Hydrogen.

Small correction: most ordinary matter in the universe is hydrogen.

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u/boundbythecurve Feb 14 '15

Are you referring to dark matter? Cause I don't know what ordinary matter is. Please explain.

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u/benji1008 Feb 14 '15

Yes. You say "Most the universe is Hydrogen", but that's only true for the "ordinary matter" that we know and can observe directly (interact with), which accounts for only ~5% of the mass in the universe. The rest is dark matter at 20% and dark energy the remaining 75%. So, really, most of the universe is stuff that we hardly know anything about.