According to the best current physics models, the universe should have collapsed shortly after inflation—the period that lasted for a fraction of a second immediately after the Big Bang.
The problem lies in part with Higgs bosons, which were produced during inflation and which explain why other particles have the masses that they do. Previous research has shown that, in the early universe, the Higgs field may have acquired large enough fluctuations to overcome an energy barrier that caused the universe to transition from its standard vacuum state to a negative energy vacuum state, which would have caused the universe to quickly collapse in on itself.
In a new paper published in Physical Review Letters, Matti Herranen at the University of Copenhagen and coauthors may have come a step closer to solving the problem by constraining the strength of the coupling between the Higgs field and gravity, which is the last unknown parameter of the standard model.
As the physicists explain, the stronger the Higgs field is coupled to gravity, the larger are the fluctuations that may eventually trigger a fatal transition to the negative energy vacuum state.
In the new paper, the scientists calculated that a collapse after inflation would have happened only if the coupling strength had been above a value of 1.
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