The Hazards Of Living Close To A Black Hole

Black Hole
Image Credit: Jeremy Perkins

Could life exist on a planet orbiting a supermassive black hole? And if so what would existence on such a planet be like?

Jeremy Schnittman, an astrophysicist at the NASA Goddard Space Flight Center in Greenbelt, Maryland, has been exploring the intriguing scenario. He has subsequently shed light on the bizarre possibility of a habitable planet orbiting a black hole in a magazine article released in the MIT Technology Review.

Time Slows Down

According to the ground-breaking sci-fi movie Interstellar, whose scientific advisor was the Nobel Prize–winning physicist Kip Thorne, the space-time surrounding such a planet would be warped in line with Einstein’s theory of general relativity. Consequently, time would pass at a slowed-down rate for those on the planet compared to elsewhere in the universe.

In Interstellar, for instance, astronauts returning from their visit to Miller’s planet orbiting the supermassive black hole called Gargantuan had experienced time at a rate of several years to every hour they spent on the planet.

Blueshifted Light

One of the thought experiments that Schnittman conducted in his study involved contemplating the kind of light and temperatures that would exist on the planet in order to make it habitable for life. Of course, any planet around a black hole would have to receive its light from a source other than a star. Instead, the planet would likely be bathed in light emanating from the black hole’s accretion disks, or hot halos of gas and matter that collect around and fall into such supermassive objects in space. This blue-shifting of light would also make the planet hotter, helping to provide the sort of temperatures that would allow for the presence of liquid and not frozen water, which is one of the fundamental conditions necessary for life.

In other words, the same gravitational force that slows down time on such a planet would also cause the light it receives to shift to higher energies. This “blueshift” effect would potentially result in incoming light being amplified to higher frequencies, including in the UV range, with exposure to such high-energy radiation posing a threat to the living cells of an organism by damaging their DNA. As Schnittman explains:

Time really affects everything around us. Not just our perception of reality, if you will, but it actually changes the reality, changes the blueshift. It can really make everything very, very different when time is running at a different rate.”

High Radiation from UV Light, X-Rays & Neutrinos

Furthermore, Schnittman raises a number of other factors that would ultimately make the possibility of a habitable planet near to a supermassive black hole even less likely. For instance, supermassive black holes are generally found at the center of galaxies, a region of space where the density of stars is extremely high. A planet circling the supermassive black hole at the center of our galaxy would have a night sky at least 100,000 times brighter than on Earth, meaning you could read at night without the use of electricity. It would also result in significantly higher amounts of background UV light and X-rays, which would produce strong harmful radiation to living creatures.

In addition, supermassive black holes are believed to create highly energetic particles known as neutrinos. These subatomic particle have very little interaction with matter and just pass through living tissue. In sufficient quantities, however, they can be harmful to life, for example in the eventuality of living organisms being unfortunate enough to be located sufficiently close to a supernova when the explosion took place. In the case of our theoretical planet close to a supermassive black hole, the volume of neutrinos emanating from the star clusters near a black hole would also be sufficient to radioactively heat up the planet and its core, eventually leading to it becoming unbearably hot.

Suffice to say, a planet orbiting a supermassive black hole would not be very conducive to the development of complex life and, as Schnittman concludes, the possibility of life surviving on such a planet was ultimately pretty unlikely indeed.

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