Max Tegmark says that when he was applying for graduate school in physics, you’d best not mention the idea of parallel universes if you wanted to be accepted. A quarter century later Tegmark, an MIT physicist, stood before the 225th meeting of the American Astronomical Society making a plenary address titled “Inflation and Parallel Universes: Science or Fiction?” that made the concepts seem downright plausible.
Tegmark’s 2014 book, Our Mathematical Universe: My Quest for the Ultimate Nature of Reality, has sparked a lot of conversation inside and outside the scientific community. AAS Vice President Jack Burns of the University of Colorado says that made Tegmark a great pick for a talk at the biannual confab of astronomers.
“Max’s approach to cosmology and big-picture questions have really been largely non-traditional, and I find that exciting,” Burns said in introducing Tegmark at the Jan. 7 meeting in Seattle. “Max is a rebel within a highly orthodox infrastructure that we all have to work in.”
Tegmark said that we as a species have a history of thinking too small.
“If we ask what we humans have figured out so far during the 13.8 billion years of our cosmic evolution, I think it’s one long story of underestimation,” Tegmark said. “We’ve again and again and again underestimated the size of our cosmos, realizing that everything that we thought existed was just a small part of something much grander: a planet, a solar system, a galaxy, clusters of galaxies, our observable universe, and maybe, as we’ll explore in this talk, a hierarchy of parallel universes.”
Tegmark said he wasn’t there to prove that inflation or parallel universes exist, but to correct some misconceptions. Most particularly, he poked at the notion that the existence of parallel universes cannot be tested scientifically. He contends that inflation predicts many phenomena that can be observed and measured. We wouldn’t throw out general relativity just because we have yet to observe a black hole directly. Likewise he said we shouldn’t dismiss parallel universes because we have yet to visit one.
Tegmark noted that inflation is more than just a mainstream idea now.
“It’s really, in my opinion, the most audacious idea we have, the most audacious extrapolation of physics so far,” he said. He noted that human growth interestingly parallels an inflationary early universe. Our number of cells double daily after conception, but the growth rates slows down soon after. The same happened with inflation. He points out that many people often think incorrectly that inflation followed the Big Bang.
“Inflation creates the Big Bang,” Tegmark said. “I think it’s more logical to say that before our Big Bang there was a cold little swoosh. That’s the early stages of inflation.”
“Inflation does this great party trick,” he added. “You can start with a tiny finite volume, less than a proton, and within there you can make an infinite volume inside the finite volume.”
“It’s pretty crazy, but that’s what you can do with general relativity,” Tegmark said. “Moreover, if there are many places where inflation doesn’t end, there’s nothing preventing you from having multiple, disconnected pockets like this.”
So how does Tegmark answer his own question? Are inflation and parallel universes science or fiction?
“Inflation has emerged as the most mainstream explanation for what happened early on,” he contended. “Whether it actually occurred and produced parallel universes is, of course, not yet settled. It remains controversial. But the key point that I want you to take away from this is that this controversy is clearly a scientific controversy, not a philosophical one, because the way it’s being settled is with data, not by people beating each other over the head with bottles in a bar.”
“2015 should bring much more clarity to what is going on,” Tegmark concluded. “Our universe is going to be an exciting place this year.”
The talk was engaging and the book should be a good read.