The ashes of the late British physicist Stephen Hawking will get a fitting resting place in Westminster Abbey, near the graves of Isaac Newton and Charles Darwin.
But you could argue that the true monuments to Hawking’s memory are his books and theoretical papers, delving into the nature of black holes, the big bang and other cosmic mysteries. And as was often the case during his life, the last paper he completed is stirring up a fuss just days after his death.
Hawking’s so-called “Final Theory” is a paper written with Belgian collaborator Thomas Hertog, and titled “A Smooth Exit from Eternal Inflation?” It hasn’t yet been published in a journal, but it’s said to be under review and is available for inspection on the ArXiv pre-print server.
The paper focuses on hypotheses having to do with cosmic inflation and the idea that our own cosmos is just one of many universes in a multiverse.
Finding the evidence that other universes exist has been a puzzler for proponents of the multiverse concept, and this week some news outlets claimed that the Hawking-Hertog paper showed how those parallel universes could be detected.
Those claims sparked a strong pushback from physicists who could actually navigate the paper’s dense, math-filled arguments. In reality, Hawking and Hertog laid out their view on how many universes might exist if Hawking’s cosmological perspective is correct.
“It’s not entirely uninteresting if you are into multiverse ideas, because then you need this information to calculate the probability of our universe,” German theoretical physicist Sabine Hossenfelder said in a posting to her Backreaction blog. “But it is also a very theoretical paper that does not say anything about observational consequences.”
Some theories have suggested that as many as 10500 kinds of universes could exist in the multiverse. If that’s the case, it may not be worth obsessing over why our universe is the way it is. We just happen to be in a universe with the right physical properties to give rise to stars, planets, life … and intelligent creatures who wonder about the meaning of the universe.
That’s what’s called the anthropic principle.
In contrast, Hawking and Hertog argue that their cosmological view is consistent with a more limited range of choices.
“Our conjecture strengthens the intuition that holographic cosmology implies a significant reduction of the multiverse to a much more limited set of possible universes,” they write. “This has important implications for anthropic reasoning.”
Katie Mack, a theoretical astrophysicist at North Carolina State University, provided a tweet-sized summary:
REALLY short summary of the paper: Hawking & Hertog found, using some VERY preliminary calculations, that the rapid expansion in the early universe (inflation) might not always create a big mess of a multiverse, but might be more likely to make a cosmos like what we see.
— Katie Mack (@AstroKatie) March 20, 2018
If it holds up, it might make it possible to draw a fairly straight line between the beginning of the cosmos and today, rather than trying to explain why we're in a Universe like ours and not one of the countless others that look totally different.
— Katie Mack (@AstroKatie) March 20, 2018
I should add that the calculations in the paper, while, again, very preliminary, connect to some really cool ideas, like ways to bring gravity and quantum mechanics together.
— Katie Mack (@AstroKatie) March 20, 2018
Hossenfelder wasn’t quite as impressed. “Stephen Hawking was beloved by everyone I know, both inside and outside the scientific community,” she wrote. “He was a great man without doubt, but this paper is utterly unremarkable.”
For further perspectives on Hawking’s “final theory,” take a look at The Register and Live Science. And for further perspectives on Hawking’s life, check out some of the video presentations that are being released or resurfaced in his honor:
- On Sunday, Smithsonian Channel will air a documentary featuring Hawking’s views on space exploration, titled “Leaving Earth: Or How to Colonize a Planet.” The BBC’s version of the show generated a hubbub last year, due to Hawking’s claim that humanity had to populate another planet within 100 years to guarantee our species’ long-term survival.
- From now through Friday, the CuriosityStream online video channel is providing free access to a three-part documentary series titled “Stephen Hawking’s Favorite Places,” in which the physicist takes viewers on cosmic tours. After Friday, the series will remain part of CuriosityStream’s standard subscription service.
- PBS has a number of online videos featuring Hawking’s life and legacy, including a documentary titled “Hawking” and a six-part series that was hosted by the physicist, called “Genius by Stephen Hawking.”
- For a fictionalized version of the disabled physicist’s life story, you can always fall back on “The Theory of Everything,” the movie that won Eddie Redmayne an Oscar in 2015 for his portrayal of Hawking. It’s available via HBO plus pay-per-view services such as Amazon, YouTube and iTunes.
- Discovery Channel has “Into the Universe With Stephen Hawking,” which focuses on big questions about time travel, extraterrestrial intelligence and, yes, the multiverse.
