Will the universe last forever?
Don’t let anybody say All Predictions Wrong is afraid of the big questions!
In the Cosmic Thoughts edition just before Christmas, yours truly promised, “A newsletter coming next spring will delve into whether dark energy overturns assumptions about the running-down of the cosmos.”
Spring has arrived and the science world just, as I hoped it would, delivered the goods with the announcement of new dark energy research findings.
I will dive right in and suggest the cosmos may last a trillion years: which might as well be forever.
And if I’m wrong, a trillion years from now you can send an outraged letter to the editor of the antimatter-powered AI running Substack.
The Big Bang hypothesis was advanced in 1927 after back-to-back major discoveries: first, there are other galaxies (Einstein composed his theories of relativity without knowing that), second, they are speeding away from us.
Initially scoffed at, the Big Bang was generally accepted by the mid-1960s, owing to a third discovery -- distant cosmological effects predicted by Big Bang thinking.
How the Big Bang might have worked, and produced (current estimate) at least 200 billion galaxies, just isn’t a Big enough question for this Substack. The universe exists: so obviously the universe came into existence!
The Really Big Question is whether the universe will end or last forever. And there’s just been a research breakthrough.
(Note -- this essay uses informal language, not postdoc lingo.)
After the Big Bang became a consensus, specialists began to debate what seemed three possible fates for creation. The three possibilities seemed to be:
1) the galaxies gradually lose impetus from the Big Bang and stop receding from us, coming to a halt; someday running out of heat and energy as everything turns cold and lifeless;
2) the galaxies never stop traveling away from us, but someday run out of heat and energy, as everything became cold and lifeless;
3) gravity overcomes momentum of the Big Bang and pulls the galaxies back together in a Big Crunch, triggering another Big Bang.
A “deep field” image from NASA’s Webb Space Telescope. The bright shiny points are not stars — are entire galaxies.
Big Crunch was the hopeful outcome. If our reality ends this way, perhaps another, future universe would fly outward to carry on. Big Crunch implied the current universe need not be the first, rather, might be the second or third or zillionth.
Possibilities 1) and 2) have the cosmos ultimately cold and lifeless, an undifferentiated blur. Mathematics prodigy Frank Ramsey, influential with 20th century physicists, said before his 1930 death, “In time the universe will cool and everything will die.”
Frank Ramsey must have been some fun at parties!
Physics may use “heat” and “energy” interchangeably – if everything cools, there’s no more energy available. “Heat death” was presumed to be the conclusion of the cosmos at least several billion years from now, so no direct relevance to our lives.
Still, assuming “the universe will cool and everything will die” makes creation seem meaningless.
Photo by Unsplash.
In 1998 a team of astronomers led by Adam Riess of Johns Hopkins University discovered a fourth possibility – expansion of the universe is speeding up. Here is me interviewing Reiss for The Atlantic shortly before he won the Nobel for physics in 2011.
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