the cosmologist spent We have spent decades trying to understand why our universe is so amazingly vanilla. doing. Coming out of the Big Bang, according to simple calculations, the universe was crumpled by gravity and blown away by repulsive dark energy.
To explain that the universe is flat, physicists have added a dramatic opening chapter to the history of the universe. They propose that the universe expanded rapidly like a balloon at the start of the Big Bang, solving the curvature. And to explain the gradual growth of the universe following the first spell of inflation, some argue that our universe is just one of many not-so-welcome universes in a vast multiverse. .
But now, two physicists have turned our vanilla universe on its head. Following a body of research initiated by Stephen Hawking and Gary Gibbons in 1977, the duo have published new calculations that suggest that cosmic plains are expected rather than rare. According to Neil Turok of the University of Edinburgh and Latham Boyle of the Perimeter Institute for Theoretical Physics in Waterloo, Canada, our universe is as it is. This is for the same reason that the air spreads evenly throughout the room. Unlikely.
The universe is “very tweaked, and though it may seem highly improbable, [they’re] I was like, ‘Wait a minute, this is my favorite one,'” said Thomas Hertog, a cosmologist at the Catholic University of Leuven in Belgium.
“This is a new contribution that uses a different method than most people have been doing,” said Steffen Gielen, a cosmologist at the University of Sheffield (UK).
The provocative conclusion is based on the mathematical trick of switching to a clock that ticks in imaginary numbers. Using an imaginary clock, Turok and Boyle were able to calculate a quantity known as entropy, as Dr. Hawking did in the 1970s. This seems to correspond to our universe. However, the imaginary-time trick is a roundabout way of calculating entropy, and without a more rigorous method the meaning of the quantity remains hotly debated. Although disturbing, many see it as a new signpost on the way to the fundamental quantum nature of space and time.
“Somehow it gives us a window into the fine structure of space-time.”
virtual path
Frequent collaborator Turok and Boyle are famous for coming up with original and unconventional ideas about cosmology. Last year, to study the potential of our universe, they turned to methods developed by physicist Richard Feynman in his 1940s.
Aiming to capture the stochastic behavior of particles, Feynman envisioned them exploring all possible routes from beginning to end: straight lines, curves, loops, infinity. He gave each path a number associated with its probability and devised a method of summing all the numbers. This ‘path integral’ technique has become a powerful framework for predicting how quantum systems are most likely to behave.
As soon as Feynman began publishing path integrals, physicists discovered an intriguing connection to thermodynamics, the time-honored science of temperature and energy. It was this bridge between quantum theory and thermodynamics that enabled Turok and Boyle’s calculations.
South African physicist and cosmologist Neil Turok is a professor at the University of Edinburgh.Photo: Gabriela Sekara/Perimeter Institute
