The great physicist Stephen Hawking helped us to appreciate that black holes really exist. In this week's article in Sky and Telescope there is discussion on yet another new type of ultra-compressed object called a "semiclassical relativistic star." Although not nearly as catchy as "black hole," the semiclassical relativistic star has the advantage of being made out of real matter.
After all, stars are made out of real matter. The standard lore has it that a massive star unlucky enough to run out of hydrogen fuel will explode as a supernova, leaving behind a neutron star or a black hole. This week we ask the relatively new question: what if there is also a third choice?
In this article physicist Carballo-Rubio considers what happens if we introduce additional quantum mechanics considerations on top of what we already know about black holes. In particular, he wanted to find out how that ill-fated massive star responds to the effects of quantum fluctuations.
This is because space is teeming with particles and anti-particles on "quantum" scales that get created in pairs and then get destroyed again nearly instantaneously as "fluctuations." It is this effect of quantum fluctuations that physicist Stephan Hawking used to show that black holes evaporate over time.
The key is that by taking quantum fluctuations into account, a repulsive force is generated which opposes the crushing downward pull of the gravitational force. In this new paper, a solution is put forward in which the two forces balance out, allowing in principle a stable solution for the star that does not include crushing the matter literally out of existence as is the case for the black hole.
These "semiclassical relativistic stars" may be detectable using the next generation of gravitational wave observatories. Until then, we still have enough on our plate to continue to understand the nature of black holes!