Gian Giudice is a rather smiling and relaxed person for someone who has just shown the Universe might be doomed. This rather shaking discovery did not induce any lack of sleep to this CERN theorist whom I met yesterday. He and his colleagues showed in their latest calculations that if the Standard Model holds beyond all what we have seen so far, the Higgs field will change its value and all matter as we know it will simply cease to exist.
But rest assured, nothing is due to happen for roughly another 10100 years, that is 1 followed-by-100-zeros years. As Gian put it, we should not stop paying our taxes. Given that the Universe is only about 13.77 billion years old, it still gives us plenty of time. One billion is “only” nine zero, a very small number in comparison with the time estimated for this change to happen.
What he and his colleagues found is that we live in a Universe having parameters sitting just on the edge. Their calculations established that the stability of our Universe depends on the specific values assumed by various entities such as the masses of some fundamental particles. Assuming the new boson found last July is the Higgs boson and has a mass of 126 GeV, and injecting the known value of the top quark mass (roughly 173 ± 1 GeV), implies the Universe sits in a meta-stable region. This means the Universe is doomed to undergo some sort of “phase transition” at some distant time in the future.
The left plot, extracted from their paper, shows three types of regions depending on the value of these two masses: the red ones indicate that the Universe would have been unstable and would not have formed. The green region corresponds to a set of values leading to eternal stability, where the Higgs field would remain unchanged forever. The yellow region describes a meta-stable region. The right plot shows that, with the assumed mass values, we fall in the meta-stable region, where eventually the Higgs field value will change, leading to a complete collapse of all atoms.
The Higgs field is a physical entity, just like a magnetic field around a magnet. And the Higgs boson is simply an excitation of this field, just like a wave is an excitation of the surface of the ocean.
This change of the Higgs field value would be just a phase transition similar to what happens when a liquid starts to boil. Bubbles form and eventually, the liquid evaporates and disappears. Since the value of the Higgs field has a direct impact on the mass of quarks and electrons, it also determines the size of atoms. If the field value changes sufficiently, the atoms equilibrium is at risk and all matter could collapse.
What is puzzling Gian Giudice the most is why are these parameters such as to put us right on the edge between the meta-stable and stable region. Why has Nature chosen such unlikely values out of all possibilities? Could it be that all values are possible and we simply happen to live in a Universe having these specific ones? This would then mean there would be zillions of other Universes out there, each one having its own set of parameters, some of them being completely unstable and undergoing rapid phase transitions, others simply never being born. Our Universe would be part of a multiverse.
Much food for thoughts! The easiest way out is still for the Large Hadron Collider (LHC) to lead to the discoveries of new particles, revealing that the Standard Model does not provide the full picture. This in turn would mean all these calculations would just be good for the garbage, as Gian Giudice is the first to point out laughingly.
Pauline Gagnon
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Tags: metastability, Universe
