Ask Ethan #86: The last light in the Universe (Synopsis)

“A single tiny light creates a space where darkness cannot exist. The light vanquishes the darkness. Try as it might, the darkness cannot conquer the light.” -Donald L. Hicks

While it might seem like there are an endless supply of stars in the Universe, the process that powers each and every one requires fuel to burn. At some point -- even though it's far in the future -- that fuel will all be spent, and all we'll be left with are stellar corpses of various types.

Image credit: E. Siegel. Image credit: E. Siegel.

But the Universe is full of second chances, and opportunities to bring not only burned-out stars back to life, but to give life to the failed stars-that-never-were. Of all the possibilities out there, what's going to give rise to the very last light in the Universe?

Image credit: Janella Williams, Penn State University, via Image credit: Janella Williams, Penn State University, via

The smart money is on colliding and merging (but not inspiraling) failed stars known as brown dwarfs. Come find out why!

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Years ago I read the very interesting article:
A dying universe: the long-term fate and evolution of astrophysical objects
Fred C. Adams and Gregory Laughlin
Rev. Mod. Phys. 69, 337 (1997) – Published 1 April 1997
This article extrapolated the longterm fate of the universe regarding all relevant physics known at that time.
Unfortunately especially with finding dark energy this has been largely obsoleted.
Your posting reminds me of this and gives at least a partial update to this old article, which I have been missing.

By Martin Selmke (not verified) on 02 May 2015 #permalink

Interesting. Of course all is contingent on what dark energy will do in the future. Ethan what about the thermal lifetime of neutron stars? I suspect it could be very long, and even though their surface areas are small, a photon is a photon. Then of course if the black holes decay, their end produces a flash of light as well.

By Omega Centauri (not verified) on 02 May 2015 #permalink

Thanks for the post. Although I'd guess that if there were civilizations still out there, a brown dwarf would be taken as a valuable prize to be mined and allowing a star to form seen as a great waste.. but I don't think that can be taken into account!

By Andrew Dodds (not verified) on 05 May 2015 #permalink

I have never taken much interest in the science of the universe however i found this article very informative and very riveting. This post makes me more interested in discovering more about the science of space. Are there any sites that you could mention that I could possibly research and find out more about this topic?