There’s a worrying problem with the ‘Higgs field’ – the energy field that gives particles their mass. It seems to be dangerously close to having an inherent instability. In the absence of particles, the Higgs field has a background, non-zero ‘vacuum energy’.
Scientists have found that this may not be the absolute minimum energy of the Higgs field, however, but merely an energy ‘trough’ instead.
An analogy would be a ball rolling down a hill, but getting trapped in a crater on its way. The ball is stable in the crater, but hasn’t attained its minimum energy by reaching the bottom of the hill.
Physicists refer to this as a ‘metastable’ state and describe the resulting background energy as a ‘false vacuum’. Our best measurements to date suggest we’re living in a Universe with a false vacuum.
But what would happen if the Higgs field were to somehow flip to a lower energy state? Such a so-called ‘vacuum decay’ would be bad news for the Universe. There would be completely different constants of nature; physics, and therefore chemistry and biology, would work completely differently, if at all.
The Universe would collapse into an entirely new state of being, destroying itself and recreating itself in a puff of energy. What that new Universe might look like, we have no way of telling.
How likely is this? For vacuum decay to be triggered, enough energy would need to be concentrated in a small enough volume. But calculations suggest there’s no known process for achieving this.
The Higgs field, is subject to the usual rules of quantum physics, however – there’s a process, called ‘tunnelling’, which allows the Higgs field to spontaneously jump to a different energy state. It’s as if our hypothetical ball simply tunnels right through the ground to escape the crater.
Thankfully, calculations show this to be extremely unlikely; occurring perhaps once in 10100 years (a 1 followed by 100 zeroes). Of course, just because something happens rarely, doesn’t mean it won’t happen at all.
In fact, somewhere in the cosmos, the vacuum decay may have already begun, racing through the Universe at the speed of light. This expanding catastrophe will destroy everything in its path and we would know nothing about it until it arrives. But let’s try not to worry.
This article is an answer to the question (asked by Kirill Jerdev, email) 'Could the Universe explode?'
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