New Scientist is running an interesting piece by Zeeya Merali on the the theories of George Chapline (Lawrence Livermore National Laboratory) and Robert Laughlin (Stanford University), which attempt to explain both dark matter and dark energy in a way that would revise our view of black holes. The duo and their colleagues have examined the collapse of massive stars in relation to quantum critical phase transitions in superconducting crystals. During such transitions, electron fluctuations slow down, suggesting what might happen on the surface of a collapsing star.
From the article:
[Chapline] and Laughlin realised that if a quantum critical phase transition happened on the surface of a star, it would slow down time and the surface would behave just like a black hole’s event horizon. Quantum mechanics would not be violated because in this scenario time would never freeze entirely. “We start with effects actually seen in the lab, which I think gives it more credibility than black holes,” says Chapline.
With this idea in mind, they – along with Emil Mottola at the Los Alamos National Laboratory in New Mexico, Pawel Mazur of the University of South Carolina in Columbia and colleagues – analysed the collapse of massive stars in a way that did not allow any violation of quantum mechanics. Sure enough, in place of black holes their analysis predicts a phase transition that creates a thin quantum critical shell. The size of this shell is determined by the star’s mass and, crucially, does not contain a space-time singularity. Instead, the shell contains a vacuum, just like the energy-containing vacuum of free space. As the star’s mass collapses through the shell, it is converted to energy that contributes to the energy of the vacuum.
Now if this view is correct, the vacuum energy inside the shell would have anti-gravity properties like those of the dark energy that is presumed to be responsible for the acceleration of the universe’s expansion. Thus we move from black holes to ‘dark energy stars,’ with observational effects like the formation of accretion disks and the gravitational effects on nearby matter remaining the same. But there is this major difference: quantum critical shells would allow particles to move both into and back out of the shell.
And this is the part of the article I found the most fascinating: the strength of the vacuum energy inside a dark energy star is related to its size. If you calculate the amount of energy that would be in a star as large as the universe, the value matches the value of dark energy calculated in the universe today. Says Chapline, “”It’s like we are living inside a giant dark energy star.” The scientists also take a shot at explaining dark energy as the result of the formation of tiny dark energy stars created in the big bang.
All this is fascinating stuff, and the development of next generation telescopes may put it to the test, since the model predicts the infrared signature to be expected from matter falling into a dark energy star. It would be a humbling lesson indeed if we were forced to abandon the older model of black hole formation in favor of these new dark stars, and a reminder that we have a long way to go before living up to Stephen Hawking’s famous statement in A Brief History of Time (New York: Bantam, 1988). Remember it?
However, if we discover a complete theory, it should in time be understandable by everyone, not just by a few scientists. Then we shall all, philosophers, scientists and just ordinary people, be able to take part in the discussion of the question of why it is that we and the universe exist. If we find the answer to that, it would be the ultimate triumph of human reason — for then we should know the mind of God. (p. 193)
The ‘if’ in Hawking’s first sentence above may be the biggest ‘if’ in the history of science.