Ask Ethan: How many stars in the night sky still exist? (Synopsis)

"I saw a star explode and send out the building blocks of the Universe. Other stars, other planets and eventually other life. A supernova! Creation itself! I was there. I wanted to see it and be part of the moment. And you know how I perceived one of the most glorious events in the universe? With these ridiculous gelatinous orbs in my skull!" -Ronald D. Moore, Battlestar Galactica

When we look out at the night sky, we aren’t seeing the Universe everywhere as it is exactly at this moment, but rather as it was some time ago. Because the speed of light is finite and the stars are many light years away, we’re seeing them as they were a long time ago in the past. Is it possible that some of the stars we’re seeing have already burned out, and that their light has stopped shining?

The night sky as seen from the California Coastal National Monument, similar to what human eyes could ideally see. Image credit: Bureau of Land Management, under a cc-by-2.0 license. The night sky as seen from the California Coastal National Monument, similar to what human eyes could ideally see. Image credit: Bureau of Land Management, under a cc-by-2.0 license.

To answer that, there’s some astrophysics we need to look into. How long do these stars live? How many of them can we see? And which ones are the ones that “die” on timescales that are meaningful for what we’re seeking?

The remnant of supernova 1987a, located in the Large Magellanic Cloud some 165,000 light years away. Image credit: Noel Carboni & the ESA/ESO/NASA Photoshop FITS Liberator. The remnant of supernova 1987a, located in the Large Magellanic Cloud some 165,000 light years away. Image credit: Noel Carboni & the ESA/ESO/NASA Photoshop FITS Liberator.

The answer is, of course, “most of them,” but is that all of them? Find out on this week’s Ask Ethan!

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“And you know how I perceived one of the most *glorious* events in the universe? With these *ridiculous* gelatinous orbs in my skull!”

Spoken as an honest, transparent evolutionist.

But if he were to think just a little harder, he’d realize that his thinking is also ridiculous, including his assessment of what is “glorious.”

How does a random, non-rational process (i.e. evolution) produce a non-random thing called rationality?
How would a non-rational being determine that it is now, by some unseen/unknown mutation, rational?

By See Noevo (not verified) on 20 Aug 2016 #permalink