Tuesday, March 25, 2014
Inflationary models predict that the rapid expansion that occurred directly after The Big Bang would have created certain noticeable patterns in the cosmos called “gravitational waves,” whose existence having been observed in 1993 resulted in that year’s Nobel prize. Plait explains:
We don’t see the waves themselves, but we can detect the effect they had on light coming from the early Universe. The waves would polarize the light, in a sense aligning the waves of light in certain ways. There are many different ways light can be polarized, but gravitational waves left over from inflation would do so in a very specific way (called B mode polarization, which twists and curls the direction of the polarization; see the image at the top of this post). Finding this kind of polarization in the light leftover from the fires of the Big Bang would be clear evidence of gravitational waves… and it was precisely this type of polarization that was finally detected by a telescope called BICEP2 (Background Imaging of Cosmic Extragalactic Polarization), located in Antarctica.
This video of BICEP2 project co-lead Professor Chao-Lin Kuo delivering the news to inflationary theory founder Professor Andrei Linde that his theory has just been proven is quite entertaining to watch:
This is kind of heady, inside-baseball stuff that physics PhDs are more qualified to discuss, but the BBC has several articles on the topic that help to unpack it in lay terms, such as this one:
From that article:
It’s an “add on” to BBT (Big Bang Theory). It proposes that about a trillionth of a trillionth of a trillionth of a second after our observable Universe got going, it went through a super-rapid expansion, taking an infinitesimally small patch of space to something about the size of a marble, before then continuing to coast outwards. (Note: space may open up faster than light, but nothing in it is moving faster than light). One of the pioneers of inflationary theory, the American Alan Guth, describes inflation “as sort of the bang in the Big Bang”. And it fixes some puzzling aspects in BBT. For example, it explains why the Universe looks so smooth on the largest scales. Inflation would have stretched away any unevenness. It also explains the structure we see in the Universe – all those galaxies and clusters of galaxies. The random quantum fluctuations that existed before inflation would have been amplified to provide the seeds for everything that came after.
While contemplating all of these questions, I find it impossible not to consider the question of what existed prior to The Big Bang. I’ve long thought it was just nothing, a pure void, what the French would call “nul,” but Einstein might have scoffed at me, saying it’s it’s a nonsensical question. One article I read compared it to asking, “What’s farther north than the North Pole?”
The shortest answers to the question of what existed before The Big Bang may either be that we simply don’t know, or else that the question cannot be meaningfully answered because our notion of time only started with The Big Bang. Prior to that event, there was simply an unmanifest singularity, a sort of void potentiality that had yet to spring into physical existence.
Sound familiar, that?
Another well-formed overview of this topic can be found in this 2013 piece on the BBC by physicist and science writer Matthew Francis:
First of all, the language we use to describe what we know and don’t know can sometimes be muddy. For instance, the Universe may be defined as all that exists in a physical sense, but we can only observe part of that. Nobody sensible thinks the observable Universe is all there is, though. Galaxies in every direction seem similar to each other; there’s no evident special direction in space, meaning that the Universe doesn’t have an edge (or a centre). In other words, if we were to instantaneously relocate to a galaxy far, far away, we’d see a cosmos very similar to the one we observe from Earth, and it would have an effective radius of 46 billion light-years. We can’t see beyond that radius, wherever we’re located.
To be honest, this is really a bit much for my primitive musician brain to grasp. Near the end of my research, I came across this interview with superstar astrophysicist Neil deGrasse-Tyson that cleared everything up for me. The video playback has been noticeably slowed down, which has created the fascinating and amusing effect of making him sound like he’s having a sort of nondual acid trip:
(image from Hubble site)