Planck data may hold evidence for what members of the physics community, like Peter Timbie from the University of Wisconsin-Madison, commonly refer to as inflation’s smoking gun: a massive collection of propagating bends and kinks in space itself, called gravitational waves.
Analogous to the way one can send a wave pulse down a taut rope, massive objects and violent events in the universe can bend and kink space itself, sending waves propagating away. Unambiguous evidence of the violent, exotic period of inflation would be traces in the CMB of these gravitational waves.
In actuality, the picture is slightly more complicated because, as Timbie somewhat reluctantly points out: “There are a whole range of models for inflation and it’s a continuum of energy scales it can occur at. The lower energy scale models wouldn’t give us anything we could see -- certainly nothing Planck would see and pretty quickly out of reach of any experiment.”
Additionally, other physicists like Daniel Chung, also of the University of Wisconsin-Madison, have discovered a handful of interesting “non-inflationary solutions” to particular problems with the original Big Bang theory. As if the story needed another twist, it turns out that, at least on paper, interactions in extra dimensions with a “’hidden’ universe” can account for certain unexplained conditions in our early cosmos.
So the picture is complicated. But what if Planck has seen evidence for a process like inflation, what next? Is our existential investigation finally over? Admittedly, probably not. As Timbie says, if the Planck data ends the search for inflation, it “would really just be the beginning.”
While we would inch ever closer to a consistent and explanatory model of reality, the philosophical gap between an observable universe’s origins and a reality’s origins would still be tough to close.
In fact, the assumption that reality is the type of thing that can have a beginning is just that, an assumption. What was reality doing a day before the Big Bang? might turn out to be a perfectly coherent question as our understanding of our origins becomes ever more clear.
And asking these types of questions and garnering evidence with telescopes like Planck might turn out to be our only path to answering our initial, existential query: how did reality get here?
David Marulli is a senior at University of Wisconsin-Madison, majoring in physics and philosophy. He can also be found on Twitter (@Delinquencyance)