3 ms·
“Observed locally” seems to be doing a lot of heavy lifting if I read things right. If the observable universe is say 1/300th of the total, wouldn’t this actua
by alex_young 6y ago
“Observed locally” seems to be doing a lot of heavy lifting if I read things right.
If the observable universe is say 1/300th of the total, wouldn’t this actually represent an increase?
- pdonis 6y agoWe can only make direct observations of stellar mass density locally. We have no direct way of knowing what the stellar mass density is "now" a billion light years away; all we can see is what it was a billion years ago. We have to reconstruct what things are like "now" elsewhere based on past data, which is all we can see.
- alex_young 6y agoThat makes sense, but isn’t it at least more likely than not that there is relatively normal distribution?
- pdonis 6y ago> isn’t it at least more likely than not that there is relatively normal distribution? No, because that would make our particular spatial location in the universe special, and that is an additional hypothesis that would require some kind of evidence in its favor, and we have none. The simplest hypothesis is that the universe is pretty much the same everywhere, and that means the average stellar density "now" should be pretty much the same everywhere.
- alex_young 6y agoThat’s what I meant by normal distribution :)
- pdonis 6y agoAh, ok. I was interpreting "normal distribution" in the sense that term is used in statistics, as "Gaussian centered on our spatial location".
- Akababa 6y agoThat's a uniform distribution
- falseprofit 6y agoThis type of casualty is to be expected when a word like 'normal' takes on a technical definition :)
- pdonis 6y ago> If the observable universe is say 1/300th of the total, wouldn’t this actually represent an increase? I'm not sure what you mean.