4 ms·
Say your prior is that something has a 1 in 1 million chance of happening in any given year. You start monitoring it. Year 1, the thing happens. Which is more
by joshuamorton 8y ago
Say your prior is that something has a 1 in 1 million chance of happening in any given year.
You start monitoring it. Year 1, the thing happens. Which is more likely:
1. You've encountered a 1/1,000,000 event
2. Your prior is incorrect and the thing happens more often than once every million years?
Without more information we can't actually answer this question with certainty, but "re-evaluate your priors" would absolutely be a thing one might suggest in response to this event.
- bsder 8y agoUnfortunately, LIGO encountered the 1/1,000,000 almost as soon as it was powered on and they've been waiting for another one like it. Probabilities are funny things ...
- Blackbeard_ 8y agoI don’t understand this comment... It’s true that the first event occurred after only two days but ligo have 11 events over two running periods at this point. https://en.m.wikipedia.org/wiki/List_of_gravitational_wave_observations https://en.m.wikipedia.org/wiki/List_of_gravitational_wave_o...
- bsder 8y agoI was under the impression from an interview that the first event that LIGO caught was held up so long before release because it was such a stupidly rare occurrence.
- bjelkeman-again 8y agoEven as there are eleven observed events so far, that is from 2 trillion galaxies in the observable universe [1]. So at 100 billion stars per galaxy [2] a guesstimate is that we are talking about 200 billion trillion stars. Seems even divided by eleven it seems pretty rare. (Not sure if the detector can “see” all those stars though.) [1] https://en.m.wikipedia.org/wiki/Observable_universe https://en.m.wikipedia.org/wiki/Observable_universe [2] https://www.livescience.com/56634-how-many-stars-are-in-the-universe.html https://www.livescience.com/56634-how-many-stars-are-in-the-...
- Zarath 8y agoWhat does 1/1000000 even mean? One every million seconds, every million minutes, every million years?
- ordu 8y agoIt means "outcome with low prior probability". Just that and nothing more. Seriously.