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posted by martyb on Saturday March 24 2018, @08:38PM   Printer-friendly
from the can-a-black-hole-radiate-back-into-a-neutron-star? dept.

Physicist Proposes Alternative to Black Holes

A physicist has incorporated a quantum mechanical idea with general relativity to arrive at a new alternative to black hole singularities. What do you get when you cross two hypothetical alternatives to black holes? A self-consistent semiclassical relativistic star, according to Raúl Carballo-Rubio (International School for Advanced Studies, Trieste, Italy) whose recently published results in the February 6th Physical Review Letters [DOI: 10.1103/PhysRevLett.120.061102] [DX] describe a new mathematical model for the fate of massive stars.

When a massive star comes to the end of its life, it goes supernova, leaving behind a dense core that — according to conventional thought — continues to collapse to form either a neutron star or black hole. To which fate a particular star is destined comes down to its mass. Neutron stars find a balance between the repulsive force of quantum mechanical degeneracy pressure and the attractive force of gravity, while more massive cores collapse into black holes, unable to fight the overwhelming pull of their own gravity.

Now, Carballo-Rubio adds an extra force into the mix: quantum fluctuations. Quantum mechanics has shown that virtual particles spontaneously pop into and out of existence — the effects can be measured best in a vacuum, but these fluctuations can happen anywhere in spacetime. These particles can be thought of as fluctuations of positive and negative energy that under normal conditions would cancel out. But the extreme gravity of compact objects breaks this balance, effectively generating negative energy. This negative energy creates a repulsive gravitational force. "The existence of quantum [fluctuations] due to gravitational fields has been known since the late 1970s," explains Carballo-Rubio. But physicists didn't know how to take this effect into account in collapsing stars.

Carballo-Rubio derived equations that combine general relativity and quantum mechanics in a way that accounts for quantum fluctuations. Moreover, he found solutions that balance attractive and negative gravity for stellar masses that would otherwise have produced black holes. Dubbing them "semiclassical relativistic stars," these compact objects do not fully collapse under their own weight to form an event horizon, and are therefore not black holes.


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  • (Score: 2) by fraxinus-tree on Sunday March 25 2018, @02:27PM

    by fraxinus-tree (5590) on Sunday March 25 2018, @02:27PM (#657905)

    Radiate more it will not. Even the neutron stars are crazily red-shifted and have only a few tens of square kilometers surface to radiate from. That's why we see mostly their accretion artifacts (the jets and the x-ray emission from the accretion disk). And the black holes are no better and we see generally the same. The objects in question lies somewhere between those two and we still have a hard time differentiating them. The main difference is the magnetic field and how it modulates the disk and the jets.

    We previously had at least two more "compact star" models between the more or less proven neutron star and the black hole - the quark star and the preon star. This Italian guy just adds a theory for one more exotic ball of mass on the road to the inevitable. Good luck seeing the differences.

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