Is the Universe Asymmetrical?
It took careful mapping of more than a million galaxies across the Universe for Oliver Philcox, a junior fellow in the Simons Society of Fellows, hosted at Columbia University, to draw his conclusion that a longstanding assumption about the Universe’s layout may be incorrect: The Universe isn’t evenly distributed, a layout we’d expect from a Universe that emerged from a single point where the Big Bang occurred. Instead, it exhibits distinct asymmetry, suggesting that some force, perhaps in the extremely early moments of the Universe, caused it to develop that way.
Philcox came to that conclusion after he used supercomputers to map the separations between millions of galaxies. With the computers, Philcox drew millions of shapes called tetrahedra, each of which connects four galaxies. He found that, when every possible tetrahedron between galaxies is mapped, the shapes, on average, orient far more in one direction than any other.
If confirmed, the results will have major implications for our understanding of the cosmos.
Columbia News sat down with Philcox to discuss the findings and what comes next for his research.
Did these results surprise you?
It’s very surprising. Gravity generally pulls things evenly in all directions. If you imagine a mass like the earth, it’s pulling everything on every side of it toward it with equal force. And we assumed that would hold on the scale of the Universe and that you’d get approximately the same number of left-handed and right-handed tetrahedra if you counted them all up. But we didn’t, which indicates that the Universe may be very different than we thought it was.
The findings have been described as “blockbuster.” Why is that?
These observations are important if true, but we should be cautious about them. The interesting thing here is that, if you’ve got an asymmetry like this, there’s got to be something that created it, and the standard picture of the Universe doesn’t create this kind of asymmetry. In the standard model, most things are controlled by gravity, which doesn’t produce imbalances like this. So this basically suggests that there is new physics going on, either in the early, primordial Universe, or in the late Universe, much more recently. Either way, it could be a smoking gun of a new physics that we don’t really understand yet.
Do you personally have a theory about when this major event that made the Universe happen took place?
I initially thought after writing this paper that the first 10-32 of a second of the Universe’s existence, which is known as inflation, is much more likely than anything more recent. There’s a huge amount of physics that we are yet to understand that could have been at work in that period.
But then I wrote another paper, now under peer review, that looks at the cosmic microwave background—the light emitted from the early Universe, often called the “afterglow” of the big bang. That paper didn’t find the same asymmetries in the cosmic microwave background that we see in galaxies. That suggests that whatever caused this asymmetry happened later in the development of the Universe, that there’s some mechanism that “hides” its signature in the new data I was looking at, or that there’s a problem with the galaxy data or analysis that I did.
What might have caused the asymmetry?
In the first 10-32 of a second of the Universe, there were particles and forces active that we don’t fully understand, and that don’t operate exactly like the particles that we do know about today. Atypical interactions in this period (possibly including gravitational waves) could generate something like the asymmetry we’re seeing. We looked at a bunch of models of this and none of them seem consistent with the data, so I don’t think we’ve come up with the solution yet. But I do think that is the most likely scenario, because physics in the extremely early Universe is so difficult to predict, and is happening at temperatures and energy scales many orders of magnitude higher than anything we can probe on Earth today.
In 1957, Columbia physicist Chien-Shiung Wu discovered that subatomic particles are asymmetrical, a discovery that sent shockwaves through the physics community. How are those observations related to this one?
That goes back to the period of the early Universe that we were talking about–the first 10-32 of a second. Though the early Universe involves different forces and particles, they can act similarly to those present today, exhibiting behavior like Wu’s discovery.
If you look at where galaxies are today, you basically get a map of the primordial Universe. Areas of the Universe that were quantum mechanically fluctuating upward have more galaxies than today, and regions that were fluctuating downward have fewer galaxies today. Physics in the primordial Universe leaves imprints on the distribution of galaxies today.
What comes next for this research?
My paper on the aymmetry of galaxies was published in Physical Review D in September, and there’s a team of researchers who are working on an analysis that shows similar findings that is undergoing peer review. Given the possible implications, we’re working to rule out any possible alternative explanations for the signal, such as measurement error, as well as looking into new physics models that could explain it.
You moved to New York six months ago from Princeton, where you got your doctorate. What do you like to do here?
I’m a classical musician by training, playing trombone and piano. So I’ve gone to quite a few concerts, mostly at Carnegie Hall and Lincoln Center. I also like trying bars and restaurants.
Do you have a favorite restaurant?
I haven’t been to any restaurants in New York twice. I keep a list of every restaurant I’ve been to. I’ve gone to about 53 and I haven’t repeated any so far.