Thursday Throughput: Parallel Universes Edition

So…have we detected a parallel universe?

NASA scientists have detected evidence of a parallel universe, right next to ours, where all the rules of physics seem to be operating in reverse.

Sounds cool. So what’s the evidence of this fantastic claim?

Let’s break this down. The University of Hawaii ran an experiment in the Antarctic called the Antarctic Impulsive Transient Antenna (ANITA). ANITA is designed to detect ultra-high energy (UHE) cosmic neutrinos — tiny particles that are traveling at near the speed of light that occasionally slam into the Earth. It’s not clear where these particles come from. ANITA is a balloon mission that floats about 37 km up above the antarctic. Most neutrinos just pass through matter without interacting with it — trillions will pass through your body by the time you finish reading this sentence. But high-energy neutrinos do interact with matter. And if one hits the antarctic ice, it may smash into an ice atom and produce a radio pulse that ANITA can detect.

ANITA was a success, detecting the UHE neutrinos. But it also detected something odd. These neutrinos should only be coming from above. But ANITA detected two events that seemed to come from below. That shouldn’t be possible, given our understanding of particle physics. Low-energy neutrinos can pass through the Earth just fine. But high energy ones can’t. Or at least shouldn’t.

What is being claimed on various websites this week, based on a quote buried in a month-old New Scientist article, is that this is evidence of a parallel universe.¹ That what we are detecting are particles interacting with our universe from one where time runs backwards and the neutrinos are coming up from the ice instead of going down into it.

Is this likely? Before I answer, let me talk a bit about parallel universes.

As we move out into the cosmos and backwards in time, our understanding of astrophysics begins to fray. We understand nearby things like stars and planets fairly well. We have a pretty good understanding of galaxies. And a fair understanding of the cosmos itself. But as we get further and further out and find ourselves looking further and further back in time, we run into limitations. Some of these limitations are fundamental — the cosmic microwave background is the furthest that light can take us; the universe was opaque to light for the first 300,000 years. But some limitations are conceptual. Our understanding of the Big Bang is mostly informed by indirect evidence — theoretical work, the structure of the cosmos and recreating the initial conditions of the universe inside particle accelerators. Our understanding can trace all the way back to the tiniest instants after the Big Bang, when the universe didn’t really even consist of matter, just fundamental forces vying it out. But beyond that, before 10^-35 seconds, we don’t have the theoretical framework. We may never have it.

We do know enough to ask some questions, though. And one of the biggest is why we are even here to ask them. The physical constants that shape our universe — the number of dimensions, the strength of the cosmological constant, etc. — are very finely tuned. If some of them were off by even a small amount, our universe might have died very quickly. Or exploded into nothingness. Or had some change that would have made life impossible. So why are they so precisely tuned to give rise to a universe that could have life in it?

Some think this reflects aspects of the Grand Unifying Theory or the Theory of Everything.² If we could reconcile Relativity and Quantum Mechanics, the answer might be obvious. Some have even turned to religion for the answers. But one of the most tantalizing is the idea that the parameters are not finely tuned.

What if, instead of creating one universe, the Big Bang created many universes — a multiverse of infinite variety, each universe having its own physical laws determined at random. Then we don’t need to fine-tune our universe. At least one of those universes will have the right formula for life to evolve and this is, naturally, the one we would inhabit.

While this sounds a bit like science fiction, it may actually be testable. It is possible that other universes could interact with ours in ways that are detectable. So far, we have not seen any signs of such interactions.

And that is where these mysterious neutrinos come in. If they are indeed traveling backward in time, that might indicate some interaction with a parallel universe, one in which time runs backward.

So…returning back to the question…have we detected a parallel universe? I’m afraid the answer is…probably not.

It’s now time for me to be Dr. Buzzkill. While this explanation is not impossible, it’s far less likely than more mundane explanations, although many scientists would faint at me describing them as mundane. It could still be some bias or error we don’t understand. It could reflect the detection of particles we didn’t know existed or tell us something about the nature of dark matter.³

That’s not to say the result isn’t exciting as all hell. If the ANITA result were confirmed, it would put a big strain on the standard model of particle physics. And while that may sound dull compared to Parallel Universe!, it is anything but. We had thought, with the discovery of the Higgs Boson, that the standard model was on pretty firm ground. If that ground crumbles beneath it…our understanding of everything would change.

Whatever the explanation, the results of the ANITA experiment were intensely interesting. And they have the possibility of throwing over the table of particle physics and cosmology that we have been carefully setting for the last century. But evidence of a parallel universe? Maybe. But probably not.

What has happened here is that a scientific speculation has been blown up a media chain of whispers from “University of Hawaii scientist speculates on nature of mystery particles” to “NASA SCIENTISTS DISCOVER PARALLEL UNIVERSE!”, a phenomenon best described by SMBC:

Same vibe pic.twitter.com/gsMW2fdknX

— Kaley Brauer (@kaleybrauer) May 20, 2020

Of course, I would be remiss if I wrote a post about a universe where time runs backward without linking to one of the best episodes of one of the best sci-fi series ever. Here’s a little clip from the Red Dwarf episode “Backwards”, where the heroes find themselves in a universe where time runs backward. And barroom brawls become barroom tidies. If you’ve never watched Red Dwarf, this story — and the ongoing quarantine — is a good excuse to start.

Addendum on May 22 Interviews with the scientists involved confirm that this is some speculation that has been blown up.

1. The quote is “below the fold”, where I can’t read it without a subscription. But I suspect that whatever Dr. Gorham said, it was more circumspect than what the papers are claiming.
2. These are theories that would unite all four fundamental forces into a single theoretical framework.
3. Dark matter being the invisible matter that provides 85% of the mass in the universe but does not interact with ordinary matter or with light. We can detect its gravitational effects but we’ve never found one particle of it.