3 ms·
One thing I'll be interested to see if there are any heavy elements in the samples. Why? Because anything from the Uranium decay chain effectively dates the cr
by cletus 6y ago
One thing I'll be interested to see if there are any heavy elements in the samples.
Why? Because anything from the Uranium decay chain effectively dates the creation of those elements.
I belong to the school of thought that believes that spacefaring life is relatively rare. By "rare" I mean we may well be the only one within the Milky Way (within our light cone). There are lots of reasons for this but a lot of people have put a lot of thought into this but it's a whole separate topic.
Anyway, this then raises the issue of the Fermi Paradox. One angle might be the relative abundance of elements heavier than iron.
Elements up to iron are relatively common in the Universe because they're created by nuclear fusion. More specifically, nuclear fusion of elements up to iron produces energy.
Heavier elements are produced by supernovae or the merger of neutron stars and/or black holes (as we've detected by LIGO in recent years). It seems like a neutron star merger is almost required for the relative abundance of such elements we have on Earth. That might be one reason why spacefaring life is "rare".
I've seen some discussion of this for Earth-bound materials suggesting they were created 80-200 million years (IIRC) before the Earth was.
So I'm curious how old samples like these. Are they from the same event or do they have a different origin? Examining such samples from other parts of the Solar System may tell us about the relative likelihood of such events on cosmic timelines.
- rmu09 6y agoI wonder, if something "large" (like a neutron star merger) happened "just" before earth was formed, where is that large object now? It doesn't seem to be in our immediate neighborhood.
- humazed 6y agoThe sun should be what's left of the supernova explosion that created the solar system.
- kbelder 6y agoWe do a full orbit around the galactic core about once every 250 million years... so our solar system has made about 20-30 orbits. It's very likely that our stellar neighborhood has completely changed since the Earth formed.
- krisoft 6y ago> “I belong to the school of thought that believes that spacefaring life is relatively rare.” I wonder why you believe that. From the next sentence it sounds like you consider humanity spacefaring life. We barelly poked our toes out from our planet. We have less than a hundred individuals who visited a different gravity well and they each only spent a relatively short amount of time there. The physical signatures of our “spacefaring-ness” is practicaly undetectable from interstellar distances. How do you know that there arent like tons of us out there?