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Comment by colechristensen | Hacker News Reader

There are as many galaxies in the observable universe as there are stars in our galaxy or… as there are bytes in 100 gigabytes. Within a factor of five or so.

The universe is flat as far as our best measurements go, if it is curved, it is with a much larger radius than the ~100 billion light year width of the observable universe.

It is indeed difficult to conceive but it is how it is, the universe is very big and has a whole lot of unique stuff in it.

Occasionally there is a lensing thing where we see the same galaxy twice or so, but not in any way to diminish the 10^11 other galaxies out there.

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What's interesting to me is, relative to human scales, cosmic space is so much more ridiculously vast than cosmic time.

Our size as a percentage of the size of the universe is tiny, and our age as a percentage of the universe's age is still tiny. But the second number is gargantuan in comparison to the first.

It always seemed odd to me that we're so close to the apparent start of the universe. 13.8 billion years isn't that long ago, given how big the future time horizon is.

We are close to the beginning of the universe, but we are about halfway through the lifetime of our sun, which formed right around when 50% of all sunlike stars that will ever be formed, had been formed. So we're actually around average in many ways.

Oh, that's interesting! That does make more sense. Most of the sun like stars that will ever exist are formed in the early universe, so it makes more sense that's why we exist when we do.

Does that mean that roughly around the time our sun dies that many more stars will also be dying ?

And then will there simply be way less stars in the universe than there are today?

Not “way” less, because most stars are lower mass than the Sun and thus have longer lifetimes (~ trillions of years in the case of red dwarfs).

Do you have a sense of how many stars are "sunlike" compared to how many stars there are in general?

This is interesting to me because there are a lot of seemingly arbitrary ways you can try to make the size and age of the universe comprehensible, and relative to a human scale is arbitrary but at least kinda means something.

And the commenter above measured our point on a cosmic time scale by looking at where on that timeline our sun formed relative to other sunlike stars. By that metric we are kind of "in the middle." But for me the natural next question is compared to stars in general, as "sunlike stars" is maybe a bit of a texas target.

AFAIK the sun is brighter than about 90% of stars in the Milky Way. We're on the larger and faster burning side, as stars go. So there will be many stars left after the sun dies. Whether you consider this to mean that saying we're about halfway through the lifetime of sunlike stars sidesteps the question depends on whether you believe that complex, energy-intensive, intelligent life is equally viable on planets orbiting red dwarfs.

One person's idea of a "side step" is another person's "refraining from making assumptions" but point noted.

For me, in my position of refraining from associating life with particular types stars, I at least feel a bit more reassurance to think of us as in the company of stars writ large, by which measure we're not so close to the end of the cosmic span of time.

That said, I think sun-like stars is a perfectly legitimate measure to put alongside the others when casting about for intuitive ways of assessing where we stand on a cosmic timeline.

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