Why this universe is more likely than any other

By | November 20, 2022

Charlie Wood writes:

Cosmologists have spent decades striving to understand why our universe is so stunningly vanilla. Not only is it smooth and flat as far as we can see, but it’s also expanding at an ever-so-slowly increasing pace, when naïve calculations suggest that — coming out of the Big Bang — space should have become crumpled up by gravity and blasted apart by repulsive dark energy.

To explain the cosmos’s flatness, physicists have added a dramatic opening chapter to cosmic history: They propose that space rapidly inflated like a balloon at the start of the Big Bang, ironing out any curvature. And to explain the gentle growth of space following that initial spell of inflation, some have argued that our universe is just one among many less hospitable universes in a giant multiverse.

But now, two physicists have turned the conventional thinking about our vanilla universe on its head. Following a line of research started by Stephen Hawking and Gary Gibbons in 1977, the duo has published a new calculation suggesting that the plainness of the cosmos is expected, rather than rare. Our universe is the way it is, according to Neil Turok of the University of Edinburgh and Latham Boyle of the Perimeter Institute for Theoretical Physics in Waterloo, Canada, for the same reason that air spreads evenly throughout a room: Weirder options are conceivable, but exceedingly improbable.

The universe “may seem extremely fine-tuned, extremely unlikely, but [they’re] saying, ‘Wait a minute, it’s the favored one,’” said Thomas Hertog, a cosmologist at the Catholic University of Leuven in Belgium. [Continue reading…]

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