Physicists have many delightful theories about how our universe might end, including one that suggests it isn\u2019t in its most stable state. If it transitions to that state, we could all be squelched into quantum oblivion. Delightful, I know. But a new study suggests this haunting scenario may be less likely than feared\u2014so there\u2019s that, at least.<\/p>\n
It\u2019s known as false vacuum decay<\/a>. In this hypothetical scenario, the universe appears stable to us, the local observer. But some calculations suggest that the universe isn\u2019t in its most stable state, in which it has the minimum possible energy\u2014a true vacuum. If the universe decides to tunnel into a more stable state, reality as we know it would be wiped out<\/a>. This cosmic transition would create an apocalyptic quantum bubble<\/a> that expands at nearly the speed of light\u2014completely rewriting the rules of physics without warning.<\/p>\n However, a research team claims to have identified a mechanism by which the early universe\u2019s rapid expansion triggered quantum effects that locked it into what the team calls a \u201ccosmic lockdown.\u201d So, even if the universe indeed exists in a false vacuum, it\u2019s unlikely that it\u2019ll decay into something else, as the team explains in a recent paper published in the Journal of Cosmology and Astroparticle Physics<\/a>.<\/p>\n \u201cThe result does not prove the universe\u2019s current state will remain stable forever or determine the specific likelihood that the Higgs field [which gives elementary particles their mass] will eventually decay,\u201d the researchers explained in a statement<\/a> from Syracuse University, where co-author Gregory Kaplanek<\/a> serves as a postdoctoral researcher.<\/p>\n Some quick physics lore <\/p>\n The story starts with the Higgs boson, which assigns<\/a> mass to an otherwise soupy universe. Fundamental particles like the electron acquire mass<\/a> by interacting with this particle-field, and it was from exploring this very useful metric that physicists realized<\/a> the universe might not be at its most stable state.<\/p>\n \u201cA useful analogy is a ball moving through a landscape of hills and valleys, where the ball represents the state of the field and the valleys represent different possible vacua,\u201d Kaplanek explained in an email to Gizmodo. \u201cThe valley we are trapped in would be the false vacuum: it appears stable because the ball sits comfortably at the bottom, but it is not the lowest-energy state available. The deeper valley is the true vacuum.\u201d<\/p>\n And quantum mechanics introduces the \u201cremarkable possibility\u201d for the field to tunnel through this hill, Kaplanek said. This would lead to dramatic changes in the properties of particles and forces, \u201cfundamentally changing the universe as we know it,\u201d he said. That makes it \u201cimportant to understand whether there are physical mechanisms that can make a false vacuum more stable,\u201d he added.<\/p>\n Quantum interactions <\/p>\n The latest findings argue that quantum fields don\u2019t exist in isolation. The team\u2019s model evaluates how quantum fields evolve in a rapidly expanding space, a setup Kaplanek clarified was \u201cmotivated by and applicable to inflationary cosmology.\u201d From the calculations, the team found that a quantum field\u2019s tunneling capabilities become curbed by decoherence\u2014a phenomenon in which quantum systems break down after interacting with their environment, acting more like classical systems.<\/p>\n There are two possible scenarios. If the field calculated in the paper were heavier relative to the rate of the universe\u2019s expansion, the universe would likely approach a true vacuum. If it were lighter, then the \u201csystem cannot keep up with the changes\u201d and would probably fall into a false vacuum, Robson Christie, the study\u2019s first author and a physicist at the University of Portsmouth in the U.K., told Quantum Insider<\/a>.<\/p>\n No squelching here? <\/p>\n