= 27d567bc2d48d9f40e9ccc20ea370b15)
army1987 comments on Where Fermi Fails: What is hard to estimate? - Less Wrong Discussion
You are viewing a comment permalink. View the original post to see all comments and the full post content.
= 783df68a0f980790206b9ea87794c5b6)
Loading…= b715d02e85f7b3b4ae65ca3d3e450868)
Subscribe to RSS Feed
Powered by Reddit
= f037147d6e6c911a85753b9abdedda8d)
You are viewing a comment permalink. View the original post to see all comments and the full post content.
Comments (46)
As for the Earth, I'd say light radionuclides such as carbon-14 are more or less in equilibrium (as many are created by cosmic rays as many decay), and so are heavy short-lived radionuclides such as radon (as many are created by uranium and thorium decaying as many decay themselves), whereas heavy long-lived radionuclides (uranium and thorium) decay with nothing replenishing them. So the total radioactivity is decreasing (at least on timescales long compared with the 2x11-year solar cycle but short compared with the Earth's age).
When an uranium atom splits, a chain begins. Where more energy is released later in this chain than in the starting decay.
In other words. The power of radiation is greater and greater for some time. For how long?
Short compared to the Earth's age.
I am not that sure. We know for the natural nuclear reactors.
E.g.
They could be deep inside the Earth as well. Heavy atoms do fall toward the center of the planet. You can't exclude ever better circumstances for the ongoing natural nuclear reactors deep down and the still rising number of them.
It is not granted, but not excluded also. It might be that the planet's interior is more and more radioactive. Possible if not probable.
Yes, but why there would be more such reactors today than there were one billion years ago?
Be cause U atoms are heavy and migrate under the influence of gravity to the center. Their relative abundance steadily rising.
I don't know if is it enough to have some effect. But if we discover some exoplanets, hotter than expected, it would be indicative for a process like that.
I don't know, it just might be, that the radioactivity of a planet rises for a longer time than usually postulated. Certainly, the Galaxy's atoms are more and more radioactive.