Such a metastable universe is not a new idea. As far back as 1979, physicists were trying to calculate the implications of the mass of the Higgs boson on cosmology. In 2001 theoretical physicists Paul Steinhardt of Princeton University and Neil Turok of the Perimeter Institute for Theoretical Physics in Canada described a cyclic universe, which alternates between expansion and contraction, and is consistent with the sort of metastability implied by the observed mass of the Higgs boson. More recently, Giuseppe Degrassi of the University of Rome and Jose Espinosa of the Autonomous University of Barcelona and their collaborators have calculated the broad implications of the Higgs mass.
"We now know with a large degree of confidence that our vacuum is on the unstable side and we were able to calculate its decay lifetime," Espinosa says. "This lifetime turns out to be way larger than the [present] age of the universe."
Most theorists don't seem to be too worried about the destruction of our universe, because metastability would not manifest itself anytime soon—if ever. Also, they expect that the LHC will find other particles in due course. Then, new calculations could indicate that the universe has more stability. Specifically, the fate of the universe depends quite sensitively not only on the Higgs but also on the mass of the top quark, another fundamental particle whose mass hovers at about 180 GeV. "The top quark strongly affects the vacuum by its quantum fluctuations because it is so heavy," Allanach says. "If the Higgs mass were really 127 GeV and the top mass were a little lower than its most likely value, then actually the universe would be completely stable and the vacuum would be in the true minimum."
Steinhardt says, "There is a tiny sliver of metastability. Why is the universe just at this point? Is this actually a profound thing we have to understand?"
But assuming that everything is known about the Standard Model and no new particles and forces will be found in the future, then the universe might be in the gray region where it is long-lived but somewhat unstable and therefore might disappear a few billions of eons from now. "And maybe not even billions of years, but billions of eons or billions of billions" of eons, Strassler stresses. "This is not something that keeps me awake."
*Editor's Note (03/28/13): This sentence was edited after posting to correct Joseph Incandela's statement about the experiment's sensitivity to detecting massive Higgs bosons.