Anika Begay
The original version From this story appeared in Quanta Magazine.
Vacuum decay, a process that could end the universe as we know it, could happen 10,000 times sooner than expected. Fortunately, it won’t happen for a long, long time.
When physicists talk about “vacuum,” the term sounds like it means empty space, and in a way it does. More specifically, it refers to a set of default settings, like the settings on a control board. When the quantum fields that permeate space are at these defaults, it’s considered empty space. Small changes to the settings create particles: Increase the electromagnetic field a little, and you get a photon. Big changes, on the other hand, are best thought of as new default settings altogether. They create a different definition of empty space, with different characteristics.
A quantum field is special because its default value can change. Called the Higgs field, it controls the mass of many fundamental particles, such as electrons and quarks. Unlike all other discovered quantum field physics, the Higgs field has a default value greater than zero. Increasing or decreasing the value of the Higgs field would increase or decrease the mass of electrons and other particles. If the Higgs field setting were zero, those particles would be massless.
We could stay at the default non-zero value forever, if it weren’t for quantum mechanics. A quantum field can “tunnel,” jumping to a new lower energy value even if it doesn’t have enough energy to pass through the intermediate higher energy settings, an effect similar to tunneling through a solid wall.
For this to happen, you need a lower energy state to tunnel to. And before building the Large Hadron Collider, physicists thought that the current state of the Higgs field might be the lowest. That belief has now changed.
The curve representing the energy required for different settings of the Higgs field has always been known to resemble a sombrero with the brim turned up. The current setting of the Higgs field can be represented as a ball resting on the bottom of the brim.
Illustration: Credit: Mark Belan for Quanta Magazine
