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In Oklo, Gabon there was a natural nuclear fission reactor about 1.7 billion years ago. The concentration of uranium and groundwater was just right that nuclea
by lizknope 5y ago
In Oklo, Gabon there was a natural nuclear fission reactor about 1.7 billion years ago. The concentration of uranium and groundwater was just right that nuclear fission occurred naturally.
We can measure the elements left behind and we have determined that the fine structure constant was the same then as it is now.
If the laws of physics have remained constant for that long then most scientists think they will remain constant in the future.
https://en.wikipedia.org/wiki/Natural_nuclear_fission_reactor#Relation_to_the_atomic_fine-structure_constant https://en.wikipedia.org/wiki/Natural_nuclear_fission_reacto...
- actually_a_dog 5y agoOh, sure, I wasn't saying the laws of physics were likely to change, simply that if they did, the SI definition of time might not be well posed. That said, although I agree the laws of physics are likely to remain constant, 1.7 billion years is only just about 12% of the age of the Universe. And, that time period only reflects the most recent 1.7 billion years. So, there's still some theoretical wiggle room there for the fine structure constant to vary over time. After all, heat death is not expected to occur for much more 100 trillion years (if that is our ultimate fate)! [0] Edit: Come to think of it, if the laws of physics aren't constant, how would it be possible to pose a coherent definition of a unit of time at all? --- [0]: https://en.wikipedia.org/wiki/Future_of_an_expanding_universe#Degenerate_Era https://en.wikipedia.org/wiki/Future_of_an_expanding_univers...