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> In other words, the likelihood that they either lived before or (will live) after us is overwhelming, since the time scale of the universe is so vast Not sur
by anonymous_sorry 3y ago
> In other words, the likelihood that they either lived before or (will live) after us is overwhelming, since the time scale of the universe is so vast
Not sure this logic makes a whole lot of sense.
Imagine a universe similar to ours, but with a lifetime cut short by a doomsday device. Would you expect any difference in the likelihood that mirror humanity coincides with another alien civilisation?
Independent of other factors, adding more time doesn't really reduce the number of civilisations existing at any one time, it gives more time for civilisations to emerge.
Your logic suggests there is a fixed number of civilisations to distribute evenly across the lifetime of the universe. Now, the number of civilisations may be limited by usable energy for life to consume rather than time - but in that case I'd expect civilisations to cluster at the beginning of time when entropy is low.
Edit: in fact Drake didn't actually include any term for age of the universe in his equation.
- zelos 3y agoI think it reduces the lower bound for how many civilisations we'd expect to exist, from our N=1 example? 1 civilisation in (say) 1 million years would suggest they're more common than 1 civilisation in 13.7 billion years?
- anonymous_sorry 3y agoTricky, but maybe. But I think I was imprecise with my language. By "age" I meant the total lifetime of the universe as a place with planets capable of supporting life, rather than the amount of time between the big bang and now.