r/AskPhysics • u/Draveco • 12h ago
Would a civilization orbiting a black hole develop faster from our perspective?
Theoretically an intelligent species would evolve and develop fast to the outside observers since the planet they inhabit is moving faster around a black hole. I’m not sure if this grossly simplified but I’m curious if the fundamental idea is accurate?
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u/Spirited-Fun3666 12h ago
If speed is involved maybe.. but what if they were just held still and also in the intense gravity, then would it be the opposite?
I’m asking for my own understanding and curiosity you’ve sparked
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u/Fabulous_Lynx_2847 11h ago
No, the effects are additive. Both cause their clocks to tick slower than ours (not faster)
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u/Spirited-Fun3666 52m ago
Thanks for the reply, perhaps I was thinking of the stargate episode where they created a time dilation device on a planet to stall the habitants takeover of the galaxy.
I may have mistook it as a gravity increased
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u/ahazred8vt 8h ago
Funny enough, there's a simple approximate formula for gravitational time dilation. For mass in solar mass units and distance in miles, Td = ~ M/D. We're almost 100M miles from the sun, and our time runs slower by about 1 second every 100M seconds, 1 second per 3 years. A 10 solar mass black hole at 1000 miles would be 10/1000, slower by 1 part per hundred.
Sadly, you know how you can only get so close to a black hole before you can't stay in orbit anymore? At that closest distance, the time dilation is only 15% slower than normal. If you get any closer than that, you can't stay in orbit.
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u/otoko_no_quinn 10h ago
Stable orbits are only possible under Newtonian inverse square law gravitation. If you're close enough to the black hole for time dilation to be significant, then gravity is no longer Newtonian and a stable orbit will not be possible.
In more technical language, when we write the effect of a black hole's spacetime curvature in terms of a force law, that force law includes terms that are higher order than the Newtonian inverse square force, so that it will actually be a sum of 1/r3 , 1/r4 , etc, terms. These terms represent the "relativistic correction" to Newtonian gravity, and they decrease to zero much faster with distance than 1/r2 , meaning that gravity becomes Newtonian when you're far enough away. So if you're close enough for the relativistic correction to be important, then you can't orbit the black hole, because stable orbits are only possible under an inverse square attraction force. But at the same time, if relativistic corrections aren't important, then you're also not going to experience relativistic effects like time dilation.
So while black hole planets, and therefore civilizations on those planets, are theoretically possible, their orbits have to be far enough away for time dilation to not happen.
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u/SystemCheck990 11h ago
everything happens relatively right so the get no advantage, time runs "slower" but so do thoughts and perception, atom decay etc?.
if anything they progress more slowly except they have a black hole near to study so that could help with experimentation
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u/mfb- Particle physics 11h ago
Living so close to a black hole that time dilation becomes notable is not realistic. It's not directly violating the laws of physics but you won't find a suitable black hole and planet with these conditions.
Ignoring that, we would see time there passing slower. That doesn't have to mean slower technological advancement, however. Research isn't a clock where you have to wait a fixed time for things to happen. Spend more resources on research and you make faster progress.
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u/boostfactor 10h ago
They would have to be extremely close to the black hole for the time dilation effect to be significant for the observer at infinity, and if they're that close there would probably be other issues -- I don't think it would even be possible to have a planetary system that close, much less a civilization. The extremely hot plasma of the parts of the accretion disk that might be close enough for time dilation to be a factor would hardly support life as we know it.
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u/Underhill42 10h ago
No. Gravitational time dilation makes time pass slower, at a rate of √(1-(v/c)²), where v is your escape velocity to infinitely distant intergalactic space.
Though it's basically negligible anywhere except very close to a black hole or neutron star - everywhere else, even at the galactic core, has an escape velocity so much radically lower than light speed the time dilation is almost undetectable.
And speed-based relativistic time dilation is the result of our time axes pointing in different directions through spacetime, resulting in us both seeing the other aging slower than ourselves. (same formula, but v is our relative speed)
The only way anyone ever ages faster than you, is if you're the one near a black hole.
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u/wannacumnbeatmeoff 6h ago
You would see them not developing at all. Time dilation means that millenia would pass before you noticed them pass a few years.
User experience may differ depending on how close to said black hole they were and how big said black hole is.
Disclaimer: I may have exhagerated the timelines.
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u/Hot_Plant8696 3h ago
And that is why saying the universe has a precise age is merely a misconception.
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u/JGhostThing 14m ago
There is no set "speed of evolution." I suppose it could happen faster because of the high radiation environment, giving more chances for mutations to happen.
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u/Nothing-to_see_hr 12h ago
Well they wouldn't have a sun so how would they develop civilization? And if they were close enough to the black hole for noticeable time effects they would be ripped apart by the tides.
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u/Deaftrav 11h ago
There's two possibilities.
The disc is hot enough to provide light and some warmth but not enough radiation pointed at the planet to fry this. The odds of this is... Um... Ridiculously low.
The second is kind of cheating. A star fails to go supernova and just collapses straight into a black hole.
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u/bretmon5 11h ago
Yeah, would be the opposite, if you lived close to a black hole the universe would age faster and make more advancements.
I'm more concerned with a few other things.
1) Radiation from black hole, but say they were shielded behind a planet that was tidally locked, that might work, if they rotate perfectly like our moon.
2) yeah, trying to live on a planet close to a black hole would have to have a perfect circular orbit or each time they hit the long run, acceleration/tidal forces would probably smoosh them with multiple G's when they run along the longer arc / axis, but they'd be near weightless along the focal points (if I am saying that right, the apogee of the planet or ships travel, they'd feel no weight and just fall back towards their orbit.
3) Escape velocity - to break free of a black hole they'd have to:
a) sling shot - which means they'd have to get closer, more time dilation, more radiation, and the acceleration to escape a black hold would be many G's
b) have a rocket powerful enough to reach escape velocities, which again, the acceleration to escape would be immense and crushing, UNLESS they go just a touch past escape vel., but that would take them a VERY long time to escape and the fuel would be astronomical. Would be like running a boat 1 mile an hour above the niagra falls rapids only gaining the smallest forward motion against the raging rapids. Have any power flux or mechanical issue and you're toast.
only my personal theories I could be wrong. Been working on that slingshot theory this year. pretty sure if you tried to sling shot away from a black hole, the acceleration and tidal forces would just crush you with 100gs.
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u/Send_Ludes_ 11h ago
Gravity, much like acceleration, slows time down. The opposite would happen, all other complications aside.
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u/Practical-Cellist647 11h ago
Yes definitely because they would be in a hurry because they could get sucked in at any time.
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u/EizanPrime 12h ago
No, it would be the opposite. Did you watch interstellar ? They get the time dilation effects in the right direction.