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/sci/ - Science & Math

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[ERROR] No.3777674 [Reply] [Original]

I could be very wrong and just plain dumb, but can someone help me understand something real quickz?


Okay so it's said that black holes are at the center of every galaxy, having many stars orbiting around it at an extremely high velocity. I can't wrap my head around the black holes gravitational immensity, yet knowing there are stars (though distant) still orbiting it.

How do these stars manage to orbit it yet not be pulled into the event horizon? Is it just a matter of velocity?

Sorry if i sound really dumb.

>> No.3777688

>How do these stars manage to orbit it yet not be pulled into the event horizon? Is it just a matter of velocity?

Imagine a whirlpool. You know how the water flows around the center in a circle while steadily being drawn closer to it?

Imagine a REALLY BIG version of this.

>> No.3777692

the close ones are in orbit.

the ones on the far edges of the galaxy are following the immense gravity of the stars in the inner part of the galaxy.
the black hole has no effect on the stars farther out.

>> No.3777704

>>3777692

Well i'm just referring to the ones at the center of the galaxy.

>>3777688

So it's just a matter of time (which will be billions of years i'm assuming) till they're pulled in?

When dealing with black holes, can there ever be velocity that would allow you to not pulled in?

>> No.3777712
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>>3777704

never mind that, i'm pretty sure i just disregarded the existence of C

>> No.3777718

>>3777692
>black hole has no effect on stars farther out

nice try, but no

gravity effects everything everywhere (that's why its colloquially called "universal"), but its effects are inversely proportional to the distance of the objects involved

>> No.3777735

In terms of just gravity, the equations work out to mean there is no difference between putting the mass in a sphere (like a star or planet) and putting all the mass in point at the centre of that sphere, if you are outside the radius of the sphere.
So you could for example replace the sun with a black hole of the same mass at the centre of the sun's position, and the planets would continue to orbit as before.

>> No.3777737

Stars orbit the black hole the same way planets orbit a star and are not completely pulled into it.

>> No.3777750

OP here.


Perhaps this whole emphasis on the mass of a black star is just what confused me? Is it all relative to other objects with different masses?


I just assumed that since electromagnetic radiation can't escape a black hole, something that's orbiting it is bound to be pulled in.

>> No.3777768

>>3777718
Motherfucker I was hoping you would take that as implied.

The gravitational effects at that scale are negligent.

>> No.3777785

>>3777750

i think you misunderstood something along the way. black holes have a finite mass, just like a star or planet. and their gravitation is only inescapable within the event horizon.

>> No.3777805

>>3777785

Nope, wait. I get it now. I just had to think about it some more.


I was thinking that if you were even getting any gravitational pull you'd be sucked into the event horizon, no matter what your velocity is. But gravity is gravity just as it would be if it's a star, it's not only until you're at or within the event horizon is when velocity doesn't matter and you're still going to be pulled in.

>> No.3777841

>>3777805

pretty much. i am no expert, so people feel free to correct me if i'm wrong.

but if a body is orbiting another body at a certain speed, its centripetal force can counterbalance the pull of gravity and cause it to continue moving around the other body at a constant distance.

>> No.3777850

flush the toilet. the stars don't have a stable orbit around the black hole they are always being pulled closer

imagine if you had a bowl and a ball. and you spinned that ball around the inside of the bowl. the velocity of the ball would increase as its orbit around the base of the bowl became smaller. eventually the ball would reach the bottom of the bowl. this is because of gravity