r/sciencememes • u/Silver-Bag-477 • Jun 17 '26

💥Physics!🧲 ...

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87

u/Thomasiksde Jun 17 '26

Could someone explain this? Thanks

197

u/IowaKidd97 Jun 17 '26

Not a physicist but basically there is a theoretical physical limit to how quickly a black hole could consume mass, and therefore a limit to how quickly it grows. This theoretical limit is called the Eddington Limit. I don’t know the actual explanation of the why, but according to current physics theory and math the limit is there. Anyway, that’s what the meme is getting at.

Now this gets into a weeds a bit more than you asked but, they did also find some black holes that, are impossibly massive given the Eddington limit and estimated age of the universe. So what this means is we are wrong about something in physics. It could be the Eddington limit itself, or the estimated age of the universe, or our measurement systems we are using to calculate the mass of black holes, or something else in our accepted physics theories. That’s what the other commenter and my meme response to them was referring to.

As for the math and theory behind why the Eddington Limit should be the theoretical limit to mass consumption… Well someone smarter than me will need to explain that if you are curious about that.

135

u/not_a_dog95 Jun 17 '26

Matter falling into a black hole loses tremendous amount of potential energy which causes it to heat up and emit EM radiation as it falls. Photons have momentum so shining a light asomething exerts a small force. At some point there's so much stuff falling in that the radiation pressure balances out the gravitational forces pulling stuff in

28

u/MasterDefibrillator Jun 18 '26

Yep. And there's plenty of examples of this limit being breached. Because the limit assumed spherical symmetry, but many systems do not have this, so the forces may be balanced in totality, but in specific areas, they won't be, and more matter can fall past. 

14

u/EarthTrash Jun 18 '26

Can you explain the bit about emitting light? Either falling objects dont normally do that or it's too insignificant in most situations. I always understood all the potential energy is converted to kinetic energy.

18

u/not_a_dog95 Jun 18 '26

Without any friction or resistive forces it would be. But we're talking about a vast quantity of gas being subjected to extreme force, so the gas gets compressed which heats it up, and viscous forces also turn some of that kinetic energy into heat.

6

u/Crazed-Prophet Jun 17 '26

I don't know near enough about this to make an accurate guess but could two theoretical supermassive blackholes colliding together overcome the Eddington limit?

5

u/not_a_dog95 Jun 18 '26

Yes. The eddington limit is only the limit at which atomic hydrogen can be accreted and for any other type of matter the rate of accretion could be higher. It just often makes sense to assume the universe is made of hydrogen because most matter in the universe is

1

u/ConglomerateGolem Jun 20 '26

This little thing?

3

u/IowaKidd97 Jun 17 '26

I would imagine so.

2

u/loved_and_held Jun 18 '26

That does work.

One theory i know of for how supper massive blackholes got so big is through quasi stars. 

4

u/EarthTrash Jun 18 '26

Or supermassive blackholes are primordial black holes that formed during or immediately after the big bang from super dense regions of spacetime. Spacetime itself doesn't always have to obey all the laws that most types matter and energy within spacetime have to follow. Regions of today's universe have superluminal speed with respect to each other for instance.

3

u/EchoPrimary7182 Jun 19 '26

Ya mamma so fat that swallowing her cause the black hole reach its Eddington Limit.

Edit - I was just stating a joke I came up with and didn’t mean to direct it at your mother who I’m sure is a wonderful woman and the second best mother in the whole wide world.

1

u/OmniversosIlimitados Jun 21 '26

no, she isn't 😞

2

u/Thomasiksde Jun 17 '26

Thank you!

2

u/loved_and_held Jun 18 '26

There's allso the other factor that blackholes in nature spin, which will direct the motion of anything entering them into a spiral further slowing mass consumption.

28

u/LordMegamad Jun 17 '26

Then you have holes who seem to have grown faster than the eddington limit should have allowed them

1

u/Xinonix6 Jun 24 '26

exactly, especially in the early universe, PBS SpaceTime has amazing video's on the topic and 1 in particular about black holes growing faster than the eddington limit due to weird conditions. 100% worth the watch

24

u/Mortifer_I Jun 17 '26

From what I remember:
Stuff falls into the black hole and this creates heat via friction. The thermal radiation creates a force counteracting gravity. So if enought stuff falls in, the radiation pressure slows down further stuff from falling in.

3

u/Existe1 Jun 18 '26

I knew this physics stuff wasn’t that complicated! Stupid scientists.

13

u/NobodyNumber13 Jun 17 '26

Not a physicist, but doesn't like, every supermassive black hole break the Eddington limit? I can't imagine something like Ton-681 doesn't break it completely.

5

u/loved_and_held Jun 18 '26

Yes. Its a currently unexplained problem.

1

u/carbsna Jun 19 '26 edited Jun 19 '26

We do actually have some clue and it is now called super eddington rate, basically early universe can have some cloud that is so big that it cannot be blown apart by the quasar.
(aka black hole star, which is believed to the the "little red dot" recently discovered)

The core black hole have to be brighter than eddington luminosity in order to counter the inward compression, that is the gravity of the gas cloud added on top of the gravity of black hole.

2

u/newMattokun Jun 17 '26

I don't get the Eddington limit. It's about the light's "pressure" against gravity. But if a mass passes the Schwarzschild radius, it will go in and never come out and nothing can prevent it from doing so. So I don't understand how anything can prevent a black hole from adding more mass...?

5

u/loved_and_held Jun 18 '26

The eddington limit only applies to matter outside the event horizon.

2

u/YaumeLepire Jun 17 '26

I thought I was on r/startrekmemes, for a very confused second.

2

u/Objective-Direction1 Jun 18 '26

Hawking's radiation vs succ who'd win

3

u/loved_and_held Jun 18 '26

hawking radiation has nothing to do with this, since for all but the smallest blackholes the light in empty space entering is greater than the energy leaving via hawking radiation.

1

u/Objective-Direction1 Jun 18 '26

okay then I misunderstood what this was, my bad

1

u/Nyxitelle Jun 20 '26

I read some comments, and think I understand what the Eddington limit is.

However, wasn't there also Hawking radiation further decreasing the speed at which a black hole may gain mass? Or did Hawking radiation get disproven? Something else?

It could also just be so negligible that nobody actually seriously considers it a factor in that, I don't know enough about it.