Reading about the latest theory that spacetime may well be some sort of a superfluid makes me wonder whether we are wasting time trying to unify the theory of general relativity and quantum mechanics. General relativity, as many of you would know, relates to how massive structures in the universe are governed, while quantum mechanics is about how the infinitesimally small is governed. These two distinct theories work perfectly on their own and independent of each other but things become weird when you apply one to the other. Relativity does not work at the quantum level and quantum mechanics does not work at the large structural level. That has been infuriating the scientific community for decades because it is the default temperament of scientists to look for theories that explain everything. It is as noble a goal as one can possibly have in science. I am not sure if it is a necessary goal.
Nevertheless, it is fascinating to see what is being proposed by Stefano Liberati of the International School for Advanced Studies and Luca Maccione of Ludwig Maximilian University. Their basic contention is that spacetime is a liquid. It is as if the universe is inside one gigantic amniotic sac containing a placenta-like superfluid. I am still trying to square this new idea with the very old idea of luminiferous aether as the medium that carries light across the universe. When I figure out I will let you know.
For now, the two scientists have been studying high-energy photons from the Crab Nebula to determine whether photons slow down traveling within this fluid. The distance between the Crab Nebula and Earth, 6,500 light years, is long enough for the photons traveling from there to us to slow down. “We show the spectrum would be severely affected by this energy loss, even if it’s a very tiny effect, because it travels for so long,” Liberati has been quoted by Clara Moskowitz of Nature as saying. Since they do not seem to be slowing down, they must be traveling through some kind of a superfluid that causes next to no dissipation. Think of this as a tsunami of x-ray and gamma rays rising from the nebula and by the time it reaches our earthly shores it should lose a lot of its force at that distance. Moskowitz does a fine job of explaining this new theory here.
My larger point, which I started with, is about the need to unify the two fundamental theories. Must we unify them? Flowing from that question is another one—must we comprehend everything? I ask because there does not seem to be a logical end of comprehension at the scale of the universe. Just as you think you have achieved an epic scientific closure—and ended physics in a way—an even greater befuddlement occurs. This approach of mine explains why I am not a scientist but just an ordinary journalist pretending to get some measure of what the deal with the universe is. One expression that I have frequently heard while reading up physics since my teenage is “emergent” properties. Moskowitz too writes about it. Emergent properties are properties or behaviors in the universe that emerge as a result of or interactions between discrete building blocks of anything. As humans we can only perceive emergent properties unless we choose to go to extraordinarily small levels.
I am reminded of the Buddhist idea of kshanika or moments. It holds that the universe is momentary and does not exist between moments. These discrete moments perhaps create emergent properties that we call the universe. Kumarila Bhatta, a great Hindu philosopher circa 660 CE, was so exercised by this Buddhist assertion to ask, "If the universe is does not exist between moments, then in which of these moments does it exist?" Not that I support one over the other but somehow the Buddhist idea of momentariness feels more in tune with the way I think. I could be thinking wrong, of course, but that is the way I currently think. But then Bhatta’s question is equally valid. In short, everything is valid and yet nothing is. Ergo, there is no need to unify the theory of general relativity and quantum mechanics. Without realizing it, I have internalized the Indian idea—or more specifically the Mahabharat’s idea—of situational logic that works in and is limited to particular situations as opposed to overarching logic that is supposed to work in all situations. (Wow! I can spin some serious non-sense).