# Life planets orbiting black-holes. Can/Do they really exist?

So, I watched Interstellar and if you watched it too you know that there's a planet orbiting a black-hole, they call it Miller's Planet. According to the movie, every hour on Miller's Planet is equivalent to 7 years on Earth due to time dilation from the black-hole.

Question: Assuming there are other life forms in the universe, is it really possible for it to be near a black-hole? Is it possible that they came to existence thousands (or even millions) of years before us, but are not as advanced as us because time on our planet is way quicker than that of theirs? If they have an assignment due tomorrow, we have, say, 100 years more time to do it (assume what else we can do in that 100 years). Or they actually are more advanced than us, but from Earth, they somehow live in the past?

• Worldbuilding.SE has a bunch of questions like these, some of which could help you. Apr 4, 2015 at 14:07
• FWIW, Greg Egan's novel Incandescence involves life in a planetoid orbiting a collapsed star. Jan 31, 2019 at 6:11

Well, first things first. It's not likely to have a planet orbiting near a black hole and in significant time dilation because the tidal effects would likely tear anything that close apart. Certainly a planet orbiting a stellar mass black hole would need to be quite far away so as to not be torn apart, so any time dilation would be pretty small.

Around a super-massive black hole, the tidal effects are smaller and a nearish orbit with some measure of time dilation is possible. (see link below for more specifics),

But a stable planetary orbit, you probably max out at about 20% time dilation and only around a super-massive black hole, where there's only 1 per galaxy. The idea of 1 day to 100 years isn't practical, it's 80 days to 100 days if you're talking about a stable planetary orbit.

and, I'm not sure you'd want to be that close to the black hole in the center of the galaxy, not because the orbit isn't stable, but because stars are in that orbit too. It might not be a safe place to be.

So, in reality, you'd want a stellar mass black hole and a distant orbit, where the time dilation would be quite small, and in that scenario, yes, life is possible because of tidal energy, so a planet could have liquid surface water and an atmosphere, even if the black hole gave off very little light and heat.

Such a planet in a tidal-energy orbit would probably be tidally locked which would protect the far side from any gamma rays the black hole spits out when it eats, so it would in theory be a good place for life. No significant light source, unless it was a binary system, so, plants would have it harder, but there would be heat.

There's another problem. The creation of black holes tends to blow everything appart in a huge explosion. It's unclear that a planet would survive a black hole's birth, so you might need a captured planet.

Finally, intelligent life . . . we really don't know enough about how common intelligent life is on other planets. Life might be fairly enough, but intelligent life is far less clear and there's other factors than just time.

Today, we simply don't know enough to predict if there's intelligent life out there or not. There probably is life elsewhere in the universe, though even that isn't 100% certain, but regarding intelligent life, there's far too many unknowns in that equation. I think a black hole might not be optimal for the formation intelligent life because of the lack of light so, much less photosynthesis, so, slower oxygen formation (if it follows the same pattern the earth does) and the unlikeliness that a planet would survive the black hole's creation.

• Hard X-rays are not known to be life friendly, so there had better not be much in the way of an accretion fisk. Apr 4, 2015 at 11:40
• I thought I covered that in the tidally locked, far side of the planet would be safe bit (well, provided the orbit avoids any gamma ray bursts ofcourse - which would be possible) What I'm not clear on, is how close a planet would need to be to have sufficient tidal effects to generate heat. You might need a 10 solar mass black hole and an elongated orbit somewhere around Mercury or Venus - but that's just a guess. I don't see why life wouldn't be possible in the right scenario. Apr 4, 2015 at 22:28
• The black hole in question is a Kerr black hole, so your objection based on stable orbits needs further work. Feb 17, 2021 at 9:08

Interstellar's "Miller's Planet" is utter rubbish...

First of all, black holes don't start out as black holes. Black holes form at the end of the life cycle of very big star (at least 25 solar masses but more frequently over 35 or 40 SMs) when it goes supernova or hypernova. Any planets in orbit around that star are going to be obliterated before the black hole becomes a black hole. We need to remember that black holes are not stars which happen to be so dense light cannot escape their gravity. Black holes are the REMNANTS of stars. And, the process of becoming a black hole obliterates planets.

Also, that planet in the movie orbiting a black hole had liquid water. There is no such thing as a goldilocks zone around a black hole like you have around a star where water is not frozen and not boiled off. That means it must be just the right distance to a heat source. The black hole isn't going to give it that heat or light.

Finally, for that "planet" to have gravitational time dilation equivalent to 7 years per earth hour, it'll have to be so close to the black hole that mile high waves will be the last thing you worry about. If you are not fried by radiation in seconds if you are that close. In fact, the planet will be ripped apart, pulverized, irradiated and basically become part of the (glowing) accretion disc depicted in the movie. That disc, BTW, can be light years across in massive black holes.

But, hey, it's a movie and it's supposed to be entertainment not science. So I can forgive all that. What I could not forgive was the blatant stupidity in the plot, such as the crew KNOWING about the time dilation but not knowing that Miller would have just landed even though they had gotten his signal for many years. They landed, had their harrowing encounter with the wave and THEN realize that as far as Miller is concerned he had just landed and only just died!?!! Bugs Bunny Science can nonetheless be entertaining. But, silly and illogical plots make a movie hard to follow.

• I agree with you on planetary orbits. A super-nova isn't planet friendly. But there should be a theoretical goldilocks tidal zone where the planet has an icy surface but has heat through tides keeping the below the surface of the planet wet and life sustaining. Granted, we're talking, primitive bacterial life, not anything we'd choose to live in. . . . and there is the problem of how the planet would get in that tidal zone after a big-nova, but it's theoretically possible that primitive life could exist around a black hole. Unlikely but possible. May 14, 2015 at 1:02
• -1 The first evidence of exoplanets were those found around pulsars, the collapsed remnants of massive stars that have been through the supernova phase. May 14, 2015 at 13:38
• These planets may have formed out of debris, may have been captured or may be the remains of larger, original planets. en.wikipedia.org/wiki/Pulsar_planet May 14, 2015 at 15:11
• o going to be orbiting non-planar to the accretion disk, providing perturbations to any possible orbits around the black hole. Jan 29, 2019 at 19:29
• Secondly, Miller's world orbits a supermassive black hole, so almost none of this answer makes any sense. Feb 17, 2021 at 9:06

According to Opatrný et al. (2016) "Life under a black sun", it might be possible to have warm temperatures around an isolated supermassive black hole thanks to the blue-shifted cosmic background radiation. Their calculations lead to an estimated equilibrium temperature of 890°C for Miller's planet (this is without the additional radiation coming from the accretion disc), which does not bode well for the watery environment shown in the movie. A planet orbiting further out might be able to support liquid water. In the past the planet would need to be located further away from the black hole because of the higher temperature of the background radiation in the early universe.

Whether such systems actually exist is another matter. The inhabitants of such a planet would have to hope that nothing came too close to the black hole, as accretion would make the environment rather hostile.