“A nightmare, long engendered in the modern mind by the mythology that follows in the wake of science, was falling off him. He had read of ‘Space’: at the back of his thinking for years had lurked the dismal fancy of the black, cold vacuity, the utter deadness, which was supposed to separate the worlds. He had not known how much it affected him till now…”
– C.S. Lewis, Out of the Silent Planet
Like Lewis, many initially envision the vacuum of space as a place of “utter deadness” and it fuels cold thoughts of a universe devoid of action. But for decades, physicists attempting to unify quantum mechanics and relativity have been accidentally painting a contradictory and compelling picture of what actually separates the worlds. The subtle, yet critical properties of the vacuum are now needed to fully describe many bizarre phenomena in the cosmos.
From the Dirac sea model of a vacuum as an ocean of negatively charged particles to the Casimir effect that dictates there will be a force between two or more objects because their presence alters the vacuum energy; such examples shatter the depressing misconception of an aether of nothingness.
Now, another possible example of the vacuum’s importance has been added. In an upcoming issue of the journal Physical Review Letters (read the preprint on the arXiv), a group of physicists from Brazil show that the nature of a vacuum around a relativistic star -a rotating neutron star that requires general relativity to explain its behavior- could determine its fate.
A vacuum field gravitates due to its quantum properties and relativity implies that as such it can affect, and be affected by, the properties of spacetime. This is also the basis of Hawking Radiation, which dictates that a black hole should thermally radiate particles and lose mass. While the Brazilian authors say the Hawking effect is “virtually unobservable” in astrophysics, other so called semiclassical gravitation effects caused by the vacuum – such as the effects they describe on neutron stars – might be.
The theory goes like this: when a neutron star forms, it could disturb the vacuum in such a way that it causes its energy density to grow exponentially. In circumstances where the energy density becomes large enough, it would “take control over the evolution of the background spacetime,” and could even become the dominant factor in deciding the outcome of how a star dies.
The group calls the process “awakening the vacuum” and when triggered, they say the effects could be seen in anywhere from the tiniest fraction of a second to a few billion years. If proven, the results could provide an important physical test of field theories, because a stable neutron star could confirm or deny what type of field surrounds it.
“Considering that 95-percent of the energy content of the universe is unknown, finding ways of testing the existence of free fields is very welcome,” the authors state in the paper. “The awakening of the vacuum energy of certain fields may determine the ultimate fate of some relativistic stars.”