Black holes, the gravitational monsters so named because no light can escape their claws, are by far the most mysterious objects in the universe.
But a new theory suggests that black holes should not be black at all. According to a new study, these black holes may rather be dark stars that are the exotic physics at their core. This mysterious new physics can cause these dark stars to emit a strange kind of radiation; that radiation in turn can explain all the mysterious dark matter in the universe, which attracts everything but emits no light.
Related: The 11 biggest unanswered questions about dark matter
Dark stars
Thanks to Einstein’s theory of general relativity, which describes how matter distorts space-time, we know that some massive stars can collapse on themselves to such an extent that they simply collapse and shrink to an infinitely small point – a singularity.
Once the singularity is formed, it surrounds itself with an event horizon. This is the ultimate one-way street in the universe. On the occasional horizon, the gravity of the black hole is so strong that you have to drive faster than the light has to do to leave. Since it is forbidden faster than the speed of light, everything that crosses the threshold is doomed forever.
Hence a black hole.
These simple but surprising statements yielded decades of observations. Astronomers watched as the atmosphere of a star was sucked into a black hole. They saw stars orbiting black holes. Physicists on earth have heard the gravitational waves emitted when black holes collide. We even took a picture of a black hole’s ‘shadow’ – the hole that cuts it out of the glow of the surrounding gas.
Related: The 12 strangest objects in the universe
And yet mysteries remain the core of science in black holes. The property that defines a black hole – the singularity – seems physically impossible, because matter cannot actually collapse to an infinitely small point.
Planck engines
This means that the current concept of black holes eventually needs to be updated or replaced with something else that can explain what is in the middle of a black hole.
But that prevents physicists from trying.
One theory of black hole singularities replaces the infinitely small points of infinitely compressed matter with something much more palatable: an incredibly small point of incredibly compressed matter case. This is called a Planck core, because the idea theorizes that matter is compressed within a black hole down to the smallest scale, the Planck length, which is 1.6 * 10 ^ minus 35 meters.
It’s … small.
With a Planck core, which would be no singular, a black hole would no longer be an event horizon – there would be no place where gravity exceeds the speed of light. But for outside observers, gravity will be so strong that it looks like an event horizon. Only extremely sensitive observations for which we do not yet have the technology can make the difference.
Dark matter
Radical problems require radical solutions, and the replacement of “singularity” by “Planck core” is therefore not so far-fetched, although the theory is hardly more than a vague sketch of an outline, without the physics or mathematics to describe that kind of environment with confidence. In other words, Planck cores are the physics equivalent of spitballing ideas.
This is a useful thing to do, because singularities need some serious out-of-the-box thinking. And there may be some bonus side effects. Like explaining the secret of dark matter, for example.
Dark matter makes up 85% of the mass of the universe, and yet it never varies with light. We can only determine its existence by its gravitational effects on normal light substances. For example, we can look at how stars revolve around the centers of the galaxies and use their rotational speed to calculate the total amount of mass in those galaxies.
In a new paper submitted to the preprint database on 15 February arXiv, physicist Igor Nikitin at the Fraunhofer Institute for Scientific Algorithms and Computing in Germany, takes the idea of ”radical singularity” and kicks it off. According to the newspaper, Planck nuclei can emit particles (because there is no horizon, these black holes are not completely black). These particles can be familiar or something new.
Perhaps it would be a form of particles that could explain dark matter. If black holes are really Planck stars, Nikitin writes, and they constantly emit a stream of dark matter, they can explain the motions of stars in galaxies.
his idea can probably not be further investigated (there is much more evidence for the existence of dark matter than just its effect on the motion of stars). But this is a good example of how we should come up with as many ideas as possible to explain black holes, because we never know what links there may be with other unsolved mysteries in the universe.
Originally published on Live Science.