According to a direct interpretation of general relativity, the Big Bang was not the beginning of "everything."
Taking Einstein's famous equations for apparent value and making as few assumptions as possible, a team of researchers rewound the clock in our Universe to find that it would not lead to a stopping point, but would lead us to a different kind of beginning. in an inverted space.
To understand what all the fuss about the Big Bang is, we need to go back a bit to understand why physicists think it may not have been the beginning of it all.
About 90 years ago a Belgian astronomer named Georges Lemaître proposed that the observed changes in the light shift of distant galaxies meant that the Universe is expanding. If it's getting bigger, it means it used to be smaller.
Continue rewinding the clock – about 13.8 billion years – and we have reached a point where space has to be confined to an incredibly small volume, also known as uniqueness.
"At this point, the Big Bang, the whole matter of the universe, would be on top of itself. The density would have been infinite," Stephen Hawking explained in his talk on The beginning of time.
There are several models that physicists use to describe the nothingness of empty space. Einstein's general relativity is one of them – he describes gravity as regards the geometry of the underlying fabric of the Universe.
The theorems proposed by Hawking and the mathematician Roger Penrose argue that solutions to the general relativity equations on an infinitely narrow scale – such as exists within a singularity – are incomplete.
In everyday terms, it is often said that physics decomposes into singularity, leading to a mixture of speculation about what little we can extract from physics that still makes sense.
Hawking only recently gave his own opinion in an interview with Neil de Grasse Tyson, where he compared the space-time dimensions of the Big Bang to the South Pole. "There is nothing south of the South Pole, so there was nothing before the Big Bang" , he said.
But other physicists argue that there is something beyond the Big Bang. Some propose that there is a mirror Universe on the other side, where time moves backwards. Others argue in favor of a recovering Universe.
With a slightly different approach, physicists Tim A. Koslowski, Flavio Mercati and David Sloan presented a new model, noting that collapse arises from a contradiction in properties at a given point in time, as defined by general relativity.
What the theorem does not imply is how the Universe, as we observe it, necessarily reaches that point in the first place.
Retracing the whole question of uniqueness, the researchers reinterpreted the existing model of shrinking space, distinguishing the space-time map from the "things" contained within it.
"All terms that are problematic turn out to be irrelevant when you work on the behavior of quantities that determine how the Universe appears from the inside out," said Sloan, a University of Oxford physicist.
What this essentially adds is a description of the Big Bang in which physics remains intact as the stage in which it acts when it reorients.
Instead of a singularity, the team calls it Janus Point, in honor of the Roman god with two faces.
The relative positions and scales of the things that compose the Universe effectively flatten themselves into a two-dimensional pancake when we step back time. Passing through Janus Point, the pancake turns the 3D again, just backwards.
What this means in physical terms is hard to say, but researchers believe that this could have profound implications for the symmetry of particle physics, perhaps even producing a universe based primarily on antimatter.
Although the idea of an inverted universe is old news, the approach of circumventing the singularity problem in this particular way is new.
"We do not introduce new principles and make no changes in Einstein's theory of general relativity – only in the interpretation that is put on objects," Sloan said.
No doubt this debate will continue in the future. Who knows? Perhaps there is a similar argument going on in the mirror Universe sometime on the other side of the Janus Point.
This research was published in F Physics B Lyrics.
A version of this story was first published in March 2018.