Once upon a time, about 13.8 billion years ago, our universe sprang from a quantum speck, ballooning to one million trillion trillion trillion trillion trillion trillion times its initial volume (by some estimates) in less than a billionth of a trillionth of a trillionth of a second. It then continued to expand at a mellower rate, in accordance with the known laws of physics.
So goes the story of cosmic inflation, the modern version of the Big Bang theory. That single short, outrageous growth spurt fits all existing cosmological data well and accounts for the universe’s largeness, smoothness, flatness and lack of preferred direction. But as an explanation of how and why the universe began, inflation falls short. The questions it raises — why the growth spurt happened, how it happened, what (if anything) occurred beforehand — have confounded cosmologists since the theory emerged in the 1980s. “We have very strong evidence that there was this period of inflation,” said Matthew Kleban, a cosmologist at New York University. “But we have no idea — or we have many, many ideas — too many ideas — what inflation was, fundamentally.”
To understand the origin of the universe, today’s cosmologists seek to identify the unknown driver of inflation, dubbed the “inflaton.” Often envisioned as a field of energy permeating space and driving it apart, the inflaton worked, experts say, like a clock. With each tick, it doubled the size of the universe, keeping nearly perfect time — until it stopped. Theorists like Kleban, then, are the clocksmiths, devising altogether hundreds of different models that might replicate the clockwork of the Big Bang.
Read more:
https://www.quantamagazine.org/20160419-string-inflation-triangles/?utm_source=Quanta+Magazine&utm_campaign=15ed4a68fa-Quanta_Newsletter_Feb_27_2015&utm_medium=email&utm_term=0_f0cb61321c-15ed4a68fa-389397069
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