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How did the universe begin? Not with a Big Bang, says physicist behind 'bouncing universe' theory

Publicado em 28 novembro 2017

Por Joseph Frankel

To any high school graduate or regular viewer of a certain CBS sitcom, the concept of the Big Bang should be somewhat familiar. In broad strokes, the theory is that the universe started from the expansion of an extremely hot, dense, single point and continues to expand to this day.

Juliano César Silva Neves, a physicist at the University of Campinas in São Paulo, Brazil, now suggests that might be wrong, in a paper published in the journalGeneral Relativity and Gravitation.

Physicist Georges Lemaître first laid the groundwork for the Big Bang theory in the 1920s when he proposed an ever-expanding universe. Astronomer Edwin Hubble’s discovery, published in 1929, that galaxies are growing ever farther from one another at faster and faster speed was taken as a key early piece of evidence that the universe started from a single point.

But Neves’s group presents an alternative explanation. Challenging the idea that “time had a beginning,” they suggest that the state of expansion in the universe came after a state of contraction.

The group’s cosmology, or model of how the universe began, outlines a “bouncing cosmology.” You can think of this, according to Yahoo News, as a kind of “Big Crunch” as opposed to a “Big Bang.” In other words, rather than coming from a single great expansion (a bang), the paper proposes that a great contraction (or crunch) preceded that expansion.

This all raises a question: How can you test a theory about what happened billions of years ago? The answer, according to Neves, is to look at black holes and other traces from when the universe may have first begun.

"Who knows, there may be remains of black holes in the ongoing expansion that date from the prior contraction phase and passed intact through the bottleneck of the bounce," Neves told In other words, Neves believes there may be remnants of black holes that predate the contraction-expansion he describes, and they may offer evidence to prove it.