A Bang-Up Job, Ctd

by Katie Zavadski & Chris Bodenner

From Michael Lemonick’s explainer on the discovery of the “first direct evidence of cosmic inflation” (visualized in the above video referenced by a reader):

[J]ust .0000000000000000000000000000000000001 seconds (give or take) after the Big Bang, the [Inflationary Universe theory] said, the cosmos underwent a burst of expansion so furious that it was briefly flying apart faster than the speed of light. Exceeding light speed is supposed to be impossible, except that that law applies only to something moving through spacetime, not spacetime itself expanding. Just as with gravitational waves, there’s plenty of reason to think it really happened, but again, no proof.

Not until now, anyway. … The telescope the researchers used—the [BICEP2]—is tuned to see the critical kind of polarization in background radiation, but there was no guarantee it ever would. Inflation theory comes in several versions, all of which posit different intensities. “In some,” says MIT’s Alan Guth, who was one of the inflationary universe theory’s original inventors, “the waves are so weak they could never be detected. To see them turn up is beautiful.”

Theoretical physicist Matt Strassler dives deeper. Jamie Condliffe describes how the BICEP2 crushes the competing popular idea of a cyclic universe:

The cyclic model, championed by Neil Turok, director of the Perimeter Institute in Canada, predicted that the Universe expanded and contracted over very long cycles. Starting with a Big Bang and ending with a Big Crunch, the growth of the Universe, Turok reckoned, would be tempered by gravity pulling it pack together, in an endless cycle of expansion and contraction. … The main benefit of the now-debunked cyclic model was that it neatly sidestepped the fact that all the matter in the Universe, every atom around us, had to come from somewhere. As far as it was concerned, everything had been here forever.

The inflation model, however, defines a very clear starting point to our Universe, before which there was… well, nobody quite knows.

MIT physics professor Max Tegmark further contrasts Inflationary Cosmology (IC) with the now-discredited Traditional Cosmology (TC):

Q: What caused our Big Bang?
TC: There’s no explanation – the equations simply assume it happened.
IC: The repeated doubling in size of an explosive subatomic speck of inflating material.

Q: Did our Big Bang happen at a single point?
TC: No.
IC: Almost: it began in a region of space much smaller than an atom.

Q: Where in space did our Big Bang explosion happen?
TC: It happened everywhere, at an infinite number of points, all at once, with no explanation for the synchronization.
IC: In that tiny region – but inflation stretched it out to about the size of a grapefruit growing so fast that the subsequent expansion made it larger than all the space that we see today.

Q: How could an infinite space get created in a finite time?
TC: There’s no explanation — the equations simply assume that as soon as there was any space at all, it was infinite in size.
IC: By exploiting a clever loophole in Einstein’s general relativity theory, inflation produces an infinite number of galaxies by continuing forever, and an observer in one of these galaxies will view space and time differently, perceiving space as having been infinite already when inflation ended.

Q: How big is space?
TC: There’s no prediction.
IC: Probably infinite.

Nature‘s conversation with lead BICEP2 researcher John Kovac is here. He and his team’s discovery finally allows Stephen Hawking to claim victory in one of his famous bets. Sarah Gray looks ahead:

Despite meticulous checking by the [BICEP2] team, there is no way to be 100% certain of these results. The findings have to be verified, but according to Time, several research projects are already underway to test the results. Researchers are also already building BICEP3, which hopes to be operational by next summer. This discovery is just the tip of the iceberg in terms of learning about the expansion of the universe[;] it opens the door to new discovery and helps narrow down possible theories.