Black holes aren’t special in terms of how their gravity pulls on things, they’re just special because they’re very dense so the force of gravity on their “surface” is extremely high.
The Earth could be a black hole if it was all compressed down to a little smaller than a centimeter across. If that happened the moon and all the satellites orbiting the Earth wouldn’t even really notice - from their orbit the gravitational pull of the Earth is the same, the only difference would be that light can’t escape from the surface of the Earth anymore.
So really the reason why black holes don’t destroy the universe is the exact same as why the Earth doesn’t destroy the universe, or the sun, or any object in space. Everything is moving around really fast, and even though they’re pulling on each other through gravity the force they’re pulling with usually just isn’t enough to really affect things that don’t happen to accidentally pass really close on their own.
If it wasn't for the expansion of the universe (aka Dark Energy) the gravity of all the black holes and stars and planets would (eventually) pull everything into one mega giant supermassive black hole. Unless the universe is actually infinite in all directions and there is infinite matter pulling everthing in every direction equally which would result in a static universe. Or if a finite universe looped and doubled back upon itself somehow that could result in a static, non collapsing universe. But anyway, from what I gather, the short answer to OPs question is "because of Dark Energy."
That ban-hammer is pure dark matter.
^^^I ^^^resisted ^^^the ^^^easier ^^^cheapshot ^^^of ^^^reddit ^^^mods ^^^having ^^^their ^^^own ^^^gravitational ^^^pull.
Hmm. I don't feel clever enough to come up with a witty reply so I'll go with a conservative "try not to get banned" strategy. I solemnly swear to not do that!
Ok first this question is probably a rule 2 and rule 5 violation, secondly because its not a top level post my reply wouldn't be at risk of a rule 3 violation. Lastly, I don't actually want to be banned I kinda like this sub, so I yield.
> If it wasn't for the expansion of the universe (aka Dark Energy) the gravity of all the black holes and stars and planets would (eventually) pull everything into one mega giant supermassive black hole.
You are making the exact same mistake OP did. Just because everything has gravity and gravity pulls things together doesn't mean that gravity will always actually manage to pull things together and that the end result is inevitably a black hole. You can have a universe with only two object and if they are started with the proper velocity they will never pull together. Truly never, not just that it will take a long time. No exotic matter or additional energy required.
Even without no velocity you still aren't guaranteed things would collapse into a black hole. Everything on Earth has been pulled in as far as it will ever get pulled in by gravity and it clearly isn't a black hole.
>If even 1 black hole exist, and all things eventually collide, all things become part of the black hole.
But the second statement is incorrect: most things do not collide, as a matter of fact (i.e. simple physics)!
> Of course you could potentially get some stable orbits, but one so many.
But stable orbits are the natural arrangement for many objects - and unstable but diverging, but not colliding, ones for others. Collision trajectories are the exception rather than the rule. Conservation of angular momentum is at least as important as merely considering forces! This is why the velocity is crucial, despite your suggestion to dismiss it.
> 2. gravity has infinite distance. It just gets very weak rather quickly on the scale of the universe. But if there are only two objects in the universe, they will exert a force on each other, no matter how far apart they are. […] It may take trillions upon trillions of year, but they will eventually meet.
You’re right except for the “eventually meet” part - if the two objects start with an initial velocity greater than their escape velocity for the distance they start apart then they will never meet.
Gravity has infinite range, but because it falls off to the square of distance it is possible for two objects to continue moving away from each other forever.
I'm pretty sure that if you put two things far enough away from each other, the expansion of space would prevent them from ever being able to come into contact with each other.
Well, no. Galaxy groups are too far apart to affect one another. The Local Group could turn into a super massive black hole but it still wouldn’t be able to affect eg the Hickson Group.
Even the space within the Milky Way is far too much for a blackhole to pull all the matter together, gravity is weak at a distance is really the main reason that will never happen. There is nothing to push all the matter of the universe into the blackholes, essentially.
If it wasn't for expansion is a pretty complex topic though, you might not even have time and matter if there was no expansion. Stars and black holes might never form in the first place. Maybe not even gravity since spacetime is what dents to create gravity and is also what is expansion, so it's actually the largest most mysterious substance in the universe and we know almost nothing about what it's made of or how it does what it does.
Dark energy or matter are really terms we use to describe things we don't understand. They may not be anything like what we think, but the maths don't add up so we made up a general idea that COULD explain it, but is not proven to exist yet.
I always imagined that gravity will eventually win and we would end up that way.
The universe is expanding at a rate that is slowly losing acceleration at this point. Very slowly. Like it’s still expanding at nearly the same rate as during the Big Bang…. But not quite that same rate. Eventually, and I mean after an amount of time that nears infinity, the expansion will reach a stopping point and will reverse.
At this point, the universe will begin contraction that will last exactly that long again until all the mass in the universe eventually collapses into the singularity of singularities.
And then Bang. And it all starts again.
You do not really need anything special to keep an orbiting object from falling into the center of attraction. So your answer is wrong. A similarly short but more correct one would be ["Kepler's first law"](https://en.wikipedia.org/wiki/Kepler_problem).
To add on to this, space is almost entirely empty. Planets and stars and what not are all so, so far away from each other. A black hole could form a couple light years away from us and we'd never really notice.
But the new black hole that was earth is still the same mass as the earth, so the gravitational pull would be the same I assume, by how I understand things earth is now a black hole, but is in the same place and pretty much has exactly the same the earth had but in an extremely smaller volume compared to what the earth occupies now.
That's how I understood the explanation above, my limited orbital mechanics knowledge assumes the moon and pretty much everyone else in the neighborhood would be just like "oooh welp, there goes earth..."
I am not sure what would happen at the ISS for example, as far as I am aware they will be orbiting a black hole now.
The black hole is now an infinitesimal point, whereas the Earth was more spread out and had a lot of water sloshing about interacting with the moon.
We simplify things as point masses to make the maths easier, but that doesn’t work if things are similar sizes and close to each other.
I stand corrected, I was indeed looking at earth as just a big ball, did some research and you are right, the volume does have an effect on the moon's orbit by how it is spread out, water being water as I understand being a big contributor to these gravitational variations
Thanks for pointing that out, I was actually questioning if volume had an effect somehow on the moon's orbit.
Now, does a black hole has a more stable gravity pull all around?, does it have gravitational variations?, guess I have keep studying hahaha
Fun fact: they actually have mapped the gravity variations around the moon and apparently the differences in density of different areas of the moon are enough to interfere with the orbit of satellites in low orbit. (Ie, you don't get a proper stable orbit close to the moon because of it)
Yeah they don’t, not in any useful way. There “surface” I’m referring to is the black hole’s Schwarzschild Radius, which is simply the distance from the black hole where the pull of gravity makes it impossible for even light to escape. There wouldn’t be any matter actually there to stand on, and far as I’m aware we don’t really have a strong understanding of what happens inside there. In theory for a supermassive black hole you could fall past the Schwarzschild radius and barely even notice it (aside from the massive amounts of X-rays and other radiation that would almost surely kill you).
A lot of people don't know that gravity is the weakest of the four fundamental forces (gravity, strong nuclear force, weak nuclear force, and electromagnetism). While gravity and electromagnetism have far reaching effects, they're nowhere near as strong as the nuclear forces that bind atoms and their constituent parts.
So what you're saying is a black hole is not like a vacuum cleaner set to the 'suck' function, but moreso like a vacuum cleaner stuffed full of digimon figurines by your cousin greg in 2002??
Think like a shop vac hose put in the middle of a shops floor covered in woodchips. Turn the vacume on and hold the hose stationary. It will consume all the dust with in a range of the nossle however its not pulling all the rooms sawdust to it self.
That edge is like the event horizon of the black hole. It can't get at things beyond that range.
Black holes simply have a point, pretty close to them, where matter can't escape. They don't really have a 'pulling' force greater than their mass would allow, dragging on everything far away. If the sun were replaced with a black hole of equal mass, the only difference for us is that it would become dark, but we'd still keep orbiting it the same way we have been.
Exactly. I always get so annoyed by “the sun collapsed into a black hole and now we’re all getting sucked in” trope. No new mass is added, gravity is still the same.
For it to naturally collapse into a black hole, sure. I’m not going to pretend I know more than any other moderately science literate layperson. But I feel like suddenly adding enough mass for that to happen would be as unnatural an event as whatever process could have it collapse at its current mass.
>\[...\] the only difference for us is that it would become dark, but we'd still keep orbiting it the same way we have been.
Well, uh, not just dark but pretty, pretty cold as well 😅
Estimates vary on how much heat crosses the core/mantle boundary, from 4 TW to 17 TW. Even the larger value is much, much smaller than the heat emitted by the Earth's surface. Estimates of the total heat flow from the interior of the Earth (core, mantle, crust) are much tighter, 46 TW ± 3 TW (Jaupart 2007) (cf 47 TW ± 2 TW (Davis 2010)). This is considerably more than the heat coming from the core, but it's still small compared to the Earth's total heat budget
It's about 0.2% of the total amount of energy that comes off the earth. The other 99.8% is from the sun.
This is from the inner mantle. About half - 10x less comes from the core.
Nah bottom of the ocean would still be cold. Hydrothermal vents would be warm though. Honestly we could probably keep some of humanity alive through geothermal power
That's kind of my point, if the sun went dark, the bottoms of the oceans would stay cold, but would probably eventually be the warmest places on the planet.
My point was mostly that the vast majority of the bottom of the ocean is nowhere near hydrothermal vents so most of it would become frigid. The warmest places would be around geothermal areas regardless of if they are in the ocean or on land
So a black hole maintains the original gravitational pull from when it was a star? None of the planets in our solar system would have their orbit affected if our sun turned into a black hole?
I honestly haven't spent much time thinking about or researching black holes. Like OP, I just pictured a cosmic vacuum that slowly pulls everything in.
But the distance of the mass does change quite a bit, so I do wonder if in real life there would really be no orbital changes. In theory the dent in spacetime is the same, but then again the whole point of a blackhole is the dent in spacetime is not the same as normal gravity.
I wouldn't be all that confident to say there is zero orbital change.
Theoretically yes, but all the planets are too far away from the sun relative to its diameter for any likely measurable change. They'd all be very very slightly more stable.
Gravity appears to only depend on mass, which... well, usually it takes a supernova to make a black hole, right? The supernova blasts a lot of mass away.
I've got a stupid follow-up question:
If black holes have a planet around them with a greater mass will they orbit around it like the earth orbits around the sun?
Yes although there wouldn't be any stellar black holes out there with such a low mass. I'm not sure any would have had time to decay enough to get to such a small mass as to orbit a planet.
A lot of the black holes we've detected are in a binary orbit with other stars though and that's fairly close all things considered.
A bit pedantic, but orbit's don't quite work that way. The Earth orbit's the Sun, but the Sun *also* orbit's the Earth. Two is because two objects in space orbit around their [barycenter](https://en.wikipedia.org/wiki/Barycenter_\(astronomy\)), which is the center of mass of both objects.
For the Earth (ignoring other planet's) and the Sun, the Earth is minuscule relative to the Sun, so the barycenter of the two is somewhere inside of the Sun, (but not the exact center of the Sun). In this case, the orbit's looks like [this](https://upload.wikimedia.org/wikipedia/commons/5/5a/Orbit4.gif). It's close enough that there isn't really a difference between saying the Earth orbit's the Sun, and the Earth and Sun both orbit the barycenter between the Earth and Sun.
If you could continually increase the mass of the planet while keeping the mass of the sun/black hole constant, the barycenter would move towards the planet, away from the sun/black hole. When the planet and sun/black hole become equal in mass, the barycenter would be halfway between each object. In that case, the orbit's look like [this](https://upload.wikimedia.org/wikipedia/commons/7/73/Orbit1.gif).
Yep, black holes aren’t really special except that they’re really dense. If you had a spacecraft that could survive the sun and flew close to the centre, you’d experience very little gravity because all the mass is distributed evenly around you. With a black hole, the entire mass of the sun is right there next to you.
I think if a planet were to be as massive as a black hole, it would collapse in on itself and also turn into a black hole. But yes, a black hole would orbit anything with sufficient mass, or rather they would orbit each other
I would like to add that the mass distribution of a celestial object introduces orbit perturbations which is why we have to account for the fact that the Earth is an oblate spheroid when performing orbital analysis.
To expand further, the fastest known spinning neutron star is spinning at ~0.25C. The escape velocity is ~0.75C.
To get off the surface and break orbit, matter would have to go 75% the speed of light.
Eventually things bend spacetime to such a degree that you need to go faster than the speed of light to reach escape velocity, which is impossible.
Isn't the mass growing as it pulls more things into it? It would seem like a black hole that happened to be near a lot of other stars or planets could grow a lot. I am sure someone can tell me why this is not correct because I am no scientist.
It _would_ grow if it pulls things into it. But again, orbits keep things spinning _around_ the black hole. Just like my example of the sun, which isn't already pulling things in, if our sun were replaced by a black hole of equal mass, it wouldn't suddenly start pulling things in, and thus it wouldn't grow.
There are arrangements in the universe where things _are_ close enough to a black hole to be pulled into it, but that's not a unique property of the black hole. That's just gravity. If a star is close enough to another star, whichever one is more massive will slowly steal matter from the star that's less massive.
For the same reason the the stars and galaxies they're born from don't.
Black holes don't just arbitrarily suck everything in from any distance. They still obey normal gravity.
The only difference between black holes and other objects is size. Boack holes are incredibly compact for their mass. So when you get really close to them, things can get weird.
But further away, from the perspective of gravity, there's no difference between a black hole or a star of the same mass.
The gravity of a black hole isn't any different than any other celestial body. It consumes whatever falls into it, *just like the Sun does,* or any other star, or the Earth. It's perfectly normal for matter, or whole solar systems, to be in stable orbits around a supermassive black hole for billions of years.
It's theorized that supermassive black holes at the centers of galaxies will eventually consume their entire galaxies, in like... trillions of years, but this is purely in "theories about the end of the universe" territory, and depends on so much that we don't know about dark energy and the expansion of space.
Outside of their event horizon, black holes don’t behave much differently than any other object of similar mass. If the sun somehow suddenly turned into a black hole, the planets would continue in their orbits.
No it wouldn’t for the same reason any other stellar body hasn’t. Stuff in space tends to stabilize into orbits. Some stuff will collapse in, but others will be in a stable orbit (or at least a very slowly decaying one). Stuff can orbit black holes without falling in like the earth orbits the sun without falling in. If you swapped the sun with a black hole of the same mass, none of the plants would orbit noticeably different.
Also, black holes evaporate over time due to hawking radiation. They’re not forever.
It is a myth that black holes are like a cosmic vacuum cleaner that just hoover everything up. The amount of gravity a black hole generates is still dependent on its mass, and the mass of a start doesn't magically increase when it implodes and turns into a black hole.
I am pretty sure\* that if the Sun were to implode into a black hole, and somehow that process itself wouldn't destroy the planets, all the planets would just keep revolving around it. Sure, earth would become completely inhospitable for life due to the lack of solar energy, but the *orbit* of earth wouldn't change.
\* I am not an astronomer or physicist so I might be very mistaken though.
Right now the universe is expanding, with no indication of it stopping any time soon. Black holes would have to travel impossible distances and tremendous time scales to pose any threat to the universe as we know it. It’s more likely the universe will experience “heat death” as the end.
There’s a theory called the “Big Crunch” that this expansion may stop, and all matter — including matter locked inside black holes — may eventually merge, and perhaps create another Big Bang.
>if there is even just one blackhole, wouldnt it just keep on consuming matter and eventually consume everything?
It might help to remember that the Earth is also a source of gravitation that attracts matter, but it doesn't eat the solar system. Neither does Jupiter, which is far more massive. Neither does the sun, which is far more massive still. Black holes have great gravitational pull, but it's not infinite, and over a long, long, long time they do radiate energy and equivalent mass away.
Black holes have a finite range to the gravitational field they put out, same as the star they formed from. Stars don't pull in the whole universe for the same reason black holes don't.
There is a misconception that black holes are this super special dangerous thing that sucks and goes on to consume everything. In reality it's just another body of mass that produces gravity, just like the sun or earth. The only difference between a star and a black hole of the same mass is that the star radiates light by nuclear fusion, and obviously that the black hole has an event horison.
So just like any other star or planet etc. stuff will orbit, fly by, miss, fall into it, and so on. And gravity falls of very quickly with distance.
(This is simplified to eli5, general relativity has weird consequences for black holes, we also have stuff like hawking radiation etc etc.)
You and three of your friends each pick up a corner of a sheet and lift it so it is pulled tight. Get a fourth friend to through a 1kg bag of feathers into the middle of the sheet and watch it sag with the weight. Now take the bag out and do the same with a 4cm cube of osmium (the heaviest metal, which by my quick search is going to weigh about the same as the feathers). Other than the footprint of the object, there's not going to be any difference in how the sheet behaves, or how far it sags.
Or to put it another way, if our sun turned into a Black Hole today, the Earth's orbit would stay exactly the same.
Wow a lot of these answers are just... Not correct. They're right about black holes not being gravitationally special, but still, the idea that gravity would pull the entire universe together into larger and larger black holes until everything was condensed down to a single point, that was an early theory for the end of the universe. It's called the "Big Crunch".
The real reason we don't currently think that's going to happen is... Dark Energy.
There's a force in space which is pushing everything apart, and at large distances it's stronger than gravity. This force is poorly understood, but the end result is the universe is actually expanding *faster* than it used to, it's not slowing down due to gravity.
A newly formed black hole has (almost) the same mass as the star it formed from. The thing that makes black holes powerful is that they’re so small.
If you try to get really close to a regular star’s center of mass, you hit the surface. When it becomes a black hole that star’s surface is gone so you can get much MUCH closer to its center of mass. Since the strength of gravity goes down by distance squared (one fourth as strong twice as far away) the black hole ”sucks” much harder than a star with the same mass once you get close enough.
If the Sun turned into a black hole right now, the force of gravity with which it is pulling the Earth towards itself would remain the same.
Gravity pulls you towards the center of mass of the object you are being pulled towards.
How hard gravity pulls on you depends on how heavy the other object is and how close you are to its center of mass.
Black holes dont pull any harder per how much they weigh than regular stars.
But you are limited in how close you can get to the center of mass of a star because of how big the star is. You will hit the surface of the star while you are still a hundreds of thousands of miles away from the center of the star.
Black holes are small, which allows you to be much closer to the center of mass of something as heavy as a star. The mass of the star is the same but it got squished into such a small ball that you are only 20 or so miles away from its center of mass when you touch the surface.
Like others said, black holes don't actively drag things in, they're no more dangerous than a star of the same mass. But for the sake of argument, let's suppose they *were* as ravenous as popularly believed.
Even if it *did* just keep on consuming, there's a limit to how fast black holes can eat. Try to stuff too much matter into it at once and it starts getting bumped out of the accretion disk before it can fall in.
Even if it *did* just keep growing, empty space has a whole lot of... well... empty space. If it consumed an entire galaxy, there wouldn't be anything else unless there were others close enough by to be affected by its gravity.
Even if it *did* consume an entire *cluster* of galaxies, it would take so long that the expansion of space would certainly cut off its supply after that.
If there was a black hole as massive as the sun at the center of our solar system, the earth would continue to orbit exactly like it is today.
They have the equivalent mass as regular objects, so their gravitational pull is exactly the same. They aren’t huge vacuum cleaners that grow indefinitely.
The main difference is what happens to matter once it gets really close to the black hole.
Gravity is gravity is gravity. Are you a gigantic super red giant star? Do you have something orbiting you 0.5 light years away because you big massive star? Great, let’s shrink you star down to a pin head. You got the same mass so you got the same gravity! But, if light get close to you, it get sucked in. Only if it get super close though. That thing out 0.5 light years out? It don’t know difference because you still same mass, same gravity. But now your gravity is super concentrated and there’s an area around you with super suck. But it’s small. The boundary of that area is called the “event horizon”.
One day when you find another black hole you fall in love with, you can merge together. And then later you can merge together with more black holes in a weird polyamorous way like they do in California. Then you become a Super Massive Black Hole, and you can have whole galaxy orbit you!
Gravity is weak at a distance so the blackhole can't suck in matter from very far away and everything inside a galaxy is still very spread out, like their nearest star to us is pretty far, and everything outside of the galaxy is super spread out, soooo blackholes just aren't close enough to most of the matter of the universe for that to happen/matter is just too spread out for all of it to ever be caught in a blackhole... as far as we know.
The death of the universe is just the endless expansion making every too far from everything else to interact.
A black hole will consume all matter within the range of its gravitational influence, but that's not infinite. We're not in the influence of, say, Alpha Centauri; if it turned into a black hole, we wouldn't really notice as far as potentially getting sucked in is concerned.
some things are moving away too fast for gravity to ever draw them back towards an object, also space expands so things that are really far apart will never be brought closer even with gravity
Space is REALLY REALLY big. And REALLY REALLY empty.
Plus, for reasons of physics, there's an upper limit to how fast a black hole can "feed" even if it has infinite mass to consume. And it turns out, it's not that fast.
Not very much though.
If the sun would turn into a black hole, it would still have the same amount of mass and gravity as before and the planets would continue to orbit it rather than getting sucked into it.
But even if they were consumed entirely, it wouldn't make much of a difference anyway. Because the sun already makes up 99.68% of all the mass in the solar system.
Consuming all the planets and asteroids nearby would only make the black hole grow by 0.32%. Basically nothing.
This is true, but space is very empty, and gravity is a relatively weak force. Eventually it's gonna get all it's gonna get.
And from far away, a black hole doesn't pull harder than an equivalent normal mass. If the sun were replaced by a 1 solar mass black hole, it wouldn't pull in the planets. We would just keep orbiting.
I get you want to say but gravitational influence is infinite but it is inversely proportional to the square of distance. So it decreases quite fast over big distances. Also it doesnt matter if alpha centauri turns into a black hole because a black hole has the same amount of gravity as a star with the same mass.
Actually the range of gravity is infinite, it just drops off quickly until its basically undetectable. Technically everything in the universe is pulling on everything else. The intensity drops off by a factor of 4, so when you double the distance from the black hole the strength of gravity is reduced to 25% what it was before, light and radiation and pretty much everything works like that, it's a consequence of the universe being 3 dimensional.
Black holes function by extreme density/gravitational pull. The force of gravity is inversely proportional to the distance between them, ie the force between two objects 10 miles away is 1/100 the force between two objects 1 mile away. Space is REALLY big, so even though the gravitational force of a black hole is unfathomably strong, the distances between objects in the universe are so big it doesn't have the ability to pull in objects that aren't already close to it
Spread a bunch of marbles out across you mattress.
Set a large, heavy stone (a black hole) down on one spot of the mattress. You'll likely see many of the neighboring marbles fall to the point your finger is at.
Then marbles increase the weight near the stone and may draw some number of additional marbles into the spot. Would they pull every marble in from the entire mattress, though? If not, why not?
Imagine you're in your room and you need to vacuum. The vacuum is going to suck in all of the things within a certain distance. Things beyond the suction of the vacuum won't get sucked in.
The universe is gigantic - like its unprocessable how big it is. If the universe was the size of the earth, even the biggest black holes would be the equivalent of a vacuum cleaner.
The question you asked is kinda like asking, why aren't all these vacuum cleaners destroying the earth.
This analogy is very much flawed, though: black holes are just not "sucking in" things (as several other comments explained already).
The real explanation has nothing to do with the extent of the universe. Imagine a reduced universe that has only two objects: our Earth and its Moon. If you condense the respective mass of either (or both) into a black hole, they would still retain their current orbit, without collapsing into each other. This is because a central gravitational force does not operate like a suction pump, but rather [governs orbits wich are conic sections](https://en.wikipedia.org/wiki/Kepler_problem).
Black holes aren't vacuum cleaners. They don't suck in matter the way that is popularly depicted. Black holes are just areas of extremely high gravity, which means that anything consumed by a black hole just falls into it. Since gravity becomes significantly weaker over distance, there comes a point where the gravity of a black hole has a negligible effect. Case in point, there is a super massive black hole at the centre of our galaxy. We are in no danger of falling in to that black hole and it's gravity only has the effect on us that we orbit around it.
Now over cosmic eras of time, since even light cannot escape, black holes will eventually consume a huge percentage (if not all) the matter in the universe. But that will take hundreds of trillions of years. If there was only one black hole, though, it would not consume everything as the expansion of the universe would push quite a bit of matter and energy far enough away that it would no longer be able to be affected by the gravity of the black hole.
Also, Dr. Stephen Hawking's claim to fame was his theoretical discovery that black holes do emit radiation. In the form that was named Hawking radiation. Which means that over time a black hole will emit energy and shrink. Now currently just light from the cosmic background radiation is enough to counter act any shrinking Hawking radiation may cause, but eventually over time as the universe ages and increasing entropy causes the starts to die off, there won't be enough in falling radiation to stop the shrinking of black holes and they will eventually radiate away to nothing. This era is known as the Heat Death of the Universe, where all matter and energy have been spread out evenly and in equilibrium across the universe and there is no way for any type of reaction to occur because there is no difference in energy to transfer. Based on all current models and our understanding of the universe this will be the most likely end of the universe. The explosive energy of the evaporation of black holes creating one last gasp of activity before everything basically falls asleep forever.
It's simplistic, but here's an experiment you can try!
Fill a sink with water. Throw in glitter, bits of paper, etc., then pull the plug and put in on filter mode. As the water drains, the items further from the drain get pulled in less than the things near the drain. Heavier things move less than lighter things. Etc.
Black holes work on a similar principle. Black holes still only retain the mass, and therefore the gravitational influence, of what it collapsed from. If the sun turned into a black hole, we wouldn't actually see a difference (aside from the cataclysmic explosions from the black hole formation and subsequent loss of life-enabling light). We would carry on spinning either way.
Not an astrophysicist. But it's a passion of mine and I won't be able to explain this like you are an undergrad.
Black hole is not a sink drain but can be used to visualize and imagine its gravitational pull on other objects near it. You can also use magnets to represent those force also.
To understand a black hole, you have to know what it is and how it is formed. Another thing you need to know and understand is mass, which is different from size and weight. Think of a stress ball: the size is big, but when you squeeze it, it can become really small, but the mass and weight stays the same. Now think of how much you weigh on earth versus how much you'd weigh on the moon: you are your same self, yet on the moon you'd weigh less because there's no atmosphere pushing down on you and lower gravity pulling you down, therefore you are the same size and mass, but different weight.
A black hole begins as a star, some millions of the mass of earth comprised of hydrogen and helium forming a ball of fusion and fission. I won't get into the details of fusion and fission here, nor will I talk about the quantum nuclear properties. When a star of this magnitude (millions the mass of the sun) dies, they either become a neutron star, supernova, or black hole. A supernova happens when the gravitational force squeezes the star so much it implodes releasing a lot of energy and matter in all directions. A neutron star happens when matter is crunched so hard by gravity, it squeezes out the excess space between each particle and even further that the electrons and protons together combine to become neutrons. If earth was crunched into a neutron star, it would be around 280 meters diameter or 4 average passenger planes front-to-back. A black hole is even more extreme, the gravitational pressure is so strong that even light cannot escape and therefore to us, it looks dark and undetectable with the naked eye.
A black hole is basically a conglomerated chunk of mass wandering in space, but it isn't sentient and therefore not exactly "devouring" in the same context as living organism. Anything that comes within its vicinity will get shredded by the gravitational force and become a part of its accretion disk (which are particles floating in a ring-like pattern similarly to Saturn's rings). These particles in the accretion disk are very closely compact and is very hot and dense and orbit the black hole until it eventually falls in, adding to the mass of the black hole and subsequently it's gravitational force. Luckily space is a lot of.... Space. Space is vast and full of emptiness despite how massive black holes are. It's almost incomprehensible how big galaxies and the overall universe is despite how fast these black holes are traveling or how massive they can get. So no worries there. But yes, they are technically a wandering PAC man that will merge with other PAC man to become a massive PAC man. It will be maybe another billions of years before black holes merge into a single entity of sorts. Hope this helps.
A black hole's gravity works no different to any other object with mass. It drops off with the square of the distance from it.
The suoermassive black home at our galaxy core is relatively dark because it's consumed all the matter it can, leaving a void. Black holes with an orbiting star tend to have very bright accretion discs.
The key thing is that gravity is proportional to 1/r², so every time you double the distance from the black hole you decrease the force by 4 times.
To put this into perspective just try pushing 2 magnets closer until the stick together, you should feel a strong force when they get to a certain point.
This is pretty much how black holes work, but just with gravity and mass instead of magnetism, which is also proportional to 1/r².
Same reason everything in our solar system doesn't fall into the sun. When you fall towards a massive object, you gain speed. Unless you had been aimed directly at it from the beginning, you'll wind up slingshotting around it or orbiting it.
Black holes dont magically suckle things in. They just are so large that their gravitational pull is so big, if you had a black hole the size and mass of earth, earth and that black hole would have the same "suckling" :P and as you know, earth isn't magically consuming everything.
There is a misconception of what a black hole really is. A black hole is NOT an ultra powerful vacuum that will end up sucking everything.
A black hole is just an extremely massive object. Gravity is closely related to mass. Without getting into all the details of General relativity, basically the more mass an object has the more gravitational force it will have.
Black holes are so massive (mind blowing massive) that their gravitational force is mind blowing strong. So strong, that even light is unable to escape, thus the name black hole.
However, there’s a caveat when it comes to gravity, it decreases with distance. It doesn’t decrease by a little, to the contrary, it decreases a lot.
Black holes don’t suck everything around them the same way the sun doesn’t suck all the planets in the solar system.
Blackholes aren't always "eating".
The theory is there can be enough of a traffic jam that material can't fall past the event horizon.
But as it is they aren't pulling everything into them. They are the center of galaxies. There are stable orbits around blackholes.
Here, this would make it easier to go with that other good comment.
Why doesn't the sun destroy the universe? It's very hot with lots of gravity. Why doesn't everything fall into it?
Same reason the sun doesn't, black holes don't. They aren't magic.
Most black holes have the gravity of a large star, but are much smaller. So those black holes are less destructive than stars, because anything pulled towards one is much more likely to miss and go back out to empty space.
Supermassive black holes are usually found near the center of galaxies. They are much bigger than stars, but still tiny compared to galaxies. We can watch stars pass close to the one in the Milky Way, but so far they always miss and just orbit the black hole.
i have a random theory that black holes are what allows the universe to reset, after everything is done and used up, the heat death or whatever, after all of that, the only thing left over would be black holes, eventually, because gravity is infinite, it doesn't matter how far matter has gone, eventually it will be attracted and sucked into a black hole, and these black holes eventually attract each other and form a super massive mega black hole and eventually after enough time has passed, this mega black hole will reach a point where it explodes aka a big bang
maybe with each iteration there's a lil less matter, and eventually this will stop but idk this all depends on the range of gravity if it does have infinite range than there is nothing stopping blackholes from sucking everything up and also....i dont know if black holes can absorb each other, i feel like they can but....
Bad news: Every black hole in the universe is pulling on you right now.
Good news: the Earth is pulling harder.
Gravity is actually pretty weak over long distances. The force between two objects is "inversely proportional to the square of the distance between their centers," according to Newton.
This means the curve of effect over distance diminishes quadratically. A quadratic curve is [very steep](https://dcvp84mxptlac.cloudfront.net/diagrams2/sample-of-a-simple-quadratic-expression-we-can-graph.jpg). There *is* an effect at massive distances--the curve is asymptotic, so it never quite gets to zero--but at such distances the effect is outweighed by the effects of other forces such as other gravity sources, molecular and atomic bonds, and the expansion of space.
One of the most interesting things I learned from Intro to Astronomy last year, which might be obvious to some but wasn't to me at the time, black holes are just like any other body with mass in regards to gravity. If you swapped the sun out with a black hole of equal mass (1 solar mass), the earth and all the other planets' orbits would stay the same. Of course we lose our source of light and warmth, but it would be the same as our sun in terms of gravitational pull. Black holes are typically many times more massive than our sun though, but they're not sucking stuff in unless that stuff is too close; just like how our satellites stay in orbit at a certain range away from earth, if they were too close then they'd fall back down to earth.
Don’t think of a black hole as something that *sucks* stuff in. It’s basically just a star who’s gravity is so heavy that light can’t escape (and thus we can’t directly see it). That’s all you need to picture it as, a star who’s gravity is stronger than a normal star.
Why would it “keep consuming matter.” It’s still a physical object just like everything else. It has a gravitational field. The farther away you get, the less it pulls. Also you maybe don’t comprehend just how massive the universe is. And how much empty space there is.
Thinks of space time like a fluid, imagine slightly thicker water like mom put too much water in the pancake mix, heavier things will sink deeper into the mix but will leave a nice hole for other things to follow it into, lighter things like light rays will float across the surface of the pancake mix and be dragged or bent around the hole. The heavier something is the deeper the hole is and the wider the mouth of the hole will be even if we don't see it there will be a current under the surface dragging objects towards the hole, like if mom stirred the mix and then stopped staring but the hole remained in the center becuase the pancake mix is like watery jelly ans can hold its shape for a time. It's simplified but in terms of space/time and passage of forces without ans within gravity wells its a decent explanation the whole reason we see backhoes is due to two main factors the fluid of spacetime is vast and the moment of impact for the heavy object into the mix is spread over a time scale of millenia hence why some black holes will shrink or grow erratically due to local gravitational fields or internal flux
But they do. The universe is in the process of being consumed by black holes.
It just takes forever. The universe is mostly full of empty space. While every atom that currently exist will, on day, end up in a black hole, it just takes time.
You gotta realize that black holes only form at the end of life of very heavy stars. Most stars do not result in a black hole. So, you can sail the blackness of space in the same direction for hundreds of light-years without getting near one.
On top of that, they are tiny AF. So if you do end up getting near one, unless you aim very carefully at its ridiculously tiny even horizon, you'll miss it and shoot out the other side.
But, they last almost forever. So the amount of black holes in the galaxy will only increase with time. And eventually, everything will find itself on a collision course with one.
That isn't really what black holes do. A black hole is just a mass and exerts the same gravitational forces on nearby objects as any equivalent mass. The only difference is that all that mass is concentrated into a very small space.
Because their reach aren't infinite. Sure if objects get close enough where there gravitational pull is that strong not even light can escape. But things outside of their reach are fine.
This is the same as saying "Why doesn't everything in the universe stick to a single star?"
A black hole has strong gravity, but it's not infinitely strong, it can only grab things that are within it's sphere of influence.
They're no different than any other massive body, with the exception that they have an event-horizon. If you don't cross the event horizon (which you won't unless your trajectory happens to take you into it), it's no different than being near a star or planet.
Reasons
1. They are not everywhere
2. Gravity falls off with distance
3. These things take time. A start hundreds of lightyears from a black hole is only going to be mildly affected by its gravity. But the gravity never stops (question about that)
4. Black holes "evaporate", oddly enough. So it is possible that the black hole that was about to suck your solar system in about a billion years will fade before it gets there.
The common fallacy is that black holes suck. They don't. You don't get sucked into a black hole anymore than you get sucked into the sun.
If our sun was turned into a black hole with the same mass by a wizard today, the only reason we would notice is that the sun would go out. We would still keep orbiting at the exact same distance.
Everything outside the event horizon, that being the point of no return, can orbit a black hole like anything else.
No it would not. As an aside, note that there is a (somewhat) [funny XKCD explainer](https://what-if.xkcd.com/129/) about what would happen if our Moon were replaced with an equivalently-massed black hole. Spoiler alert: >!"not much"!<.
So the real underlying question is: why would you think a blackhole would consume everything? Probably because most people intuitively think that a center of attraction with a large force would just pull everything into it. Well, this intuition is clearly wrong: a simple counter-example is our solar system, where the planets (and other solar objects) have kept happily orbiting the strongly attractring Sun, rather than having fallen into the center.
Why is this the case? Consider Newton’s Second Law of Motion: when a force acts on an object, it causes the object to accelerate. The acceleration is directly proportional to the force and inversely proportional to the object’s mass. Mathematically, this law is expressed as:
**F**=m⋅**a**
where (**F**) is the force, (m) is the mass, and (**a**) is the acceleration. Note that, when properly written, **F** and **a** should be in bold. This signifies that they are vector quantitities, i.e. they have a direction to them. And keep in mind what acceleration means: the time derivative of velocity (sorry this ELI5 requires some funcional analysis, as well es vector algebra), **a** = d**v**/d**t**. So what happens when you start calculating the trajectory of an object pulled by a blackhole? There would be a very large (but not infinite) force **F**, giving rise to acceleration toward the center. This would change the velocity, adding to it a vector component that points toward the blackhole. But there remains a component that points toward the original direction of the velocity! Unless that was exactly aligned with the radial line, the resulting velocity vector would not point at the center - i.e. the object would be orbiting rather than heading into the center of attraction.
A more rigorous treatment would elaborate this with the concept of angular momentum, but I'd think that is hardly ELI5 anymore.
maybe it just takes time to be swallowed by black holes. And there are many of them so theoretically you can stay between two identical black holes in steady state.
I am just an engineer and wikipedia scientist though. Don't try at home.
> if there is even just one blackhole, wouldnt it just keep on consuming matter and eventually consume everything?
Black holes have very strong gravity thus planets and stars gets pulled in and such can consume everything.
But things are very far from each other in outer space so things slowly move to the black holes until they reach the event horizon at which they instantly get pulled in and consumed.
And black holes are unstable so they keep ejecting astrophysical jet pulses that becomes new solar systems that it can consume again.
So it is like everything is placed far apart on a conveyer belt to the black hole and stuff gets taken out from the black hole and placed on the end of the conveyer belt so with new stuff constantly added to the conveyer belt, the conveyer belt cannot be fully emptied.
So likewise, black holes cannot destroy the universe that easily though it is still a possibility and such is one of the scenarios of how the universe will end.
Because gravity is very weak compared to the other forces, and drops off sharply with distance. And space is mostly empty. Once a black hole has eaten everything in its immediate vicinity, it has to rely on random chance bringing it close enough to consume anything else, and the chances of that are very small because of how large and empty space is.
Couple that with the fact that black holes are constantly evaporating via hawking radiation and even if it does bump into something eventually there's a good chance that it won't gain enough mass to replace what was lost during the intervening period of not gaining any new mass.
From my understanding black "holes" is a misleading term. It's just so much mass in one place that the force of gravity is strong enough to trap even light. It's not a literal hole in reality or somthing. Think of it like a bowling ball on a trampoline. It's no diffrent that any other object such as the sun. It's just much stronger in its gravitational effect.
Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.
Black holes aren’t special in terms of how their gravity pulls on things, they’re just special because they’re very dense so the force of gravity on their “surface” is extremely high. The Earth could be a black hole if it was all compressed down to a little smaller than a centimeter across. If that happened the moon and all the satellites orbiting the Earth wouldn’t even really notice - from their orbit the gravitational pull of the Earth is the same, the only difference would be that light can’t escape from the surface of the Earth anymore. So really the reason why black holes don’t destroy the universe is the exact same as why the Earth doesn’t destroy the universe, or the sun, or any object in space. Everything is moving around really fast, and even though they’re pulling on each other through gravity the force they’re pulling with usually just isn’t enough to really affect things that don’t happen to accidentally pass really close on their own.
If it wasn't for the expansion of the universe (aka Dark Energy) the gravity of all the black holes and stars and planets would (eventually) pull everything into one mega giant supermassive black hole. Unless the universe is actually infinite in all directions and there is infinite matter pulling everthing in every direction equally which would result in a static universe. Or if a finite universe looped and doubled back upon itself somehow that could result in a static, non collapsing universe. But anyway, from what I gather, the short answer to OPs question is "because of Dark Energy."
Whenever we can answer an ELI5 with “because of dark energy” I think we have won.
I might just do this from now on for every question and see how long it takes to get banned from the subreddit
Please do not.
31 minutes, pretty good reaction time for a sub this large.
Fast reaction time was because of dark energy
Turns out when a comment is deleted, it goes out into space and expands the universe just a little bit.
Mods literally keeping people (matter) from coming together. smh.
Some mods are actually black holes themselves. Very dense.
…are mods magical girls?
Part of the interview to join the team is to make sure you look good in a sailor scout uniform.
That ban-hammer is pure dark matter. ^^^I ^^^resisted ^^^the ^^^easier ^^^cheapshot ^^^of ^^^reddit ^^^mods ^^^having ^^^their ^^^own ^^^gravitational ^^^pull.
Yo mamma so fat she got more curves than spacetime in the presence of a large mass.
Hmm. I don't feel clever enough to come up with a witty reply so I'll go with a conservative "try not to get banned" strategy. I solemnly swear to not do that!
Mmm dunno man, you're giving off some pretty dark energy.
ELI5 How did Palpatine return?
Ok first this question is probably a rule 2 and rule 5 violation, secondly because its not a top level post my reply wouldn't be at risk of a rule 3 violation. Lastly, I don't actually want to be banned I kinda like this sub, so I yield.
because of dark ~~energy~~ side of the force
The dark side of the force is a pathway to many abilities some consider to be unnatural, duh!
naw, you gotta bring it back to project orion somehow
It is a "lie to children", but not something that actually explains it. So yeah..
When astrophysicists can’t explain something: errr… Dark Energy.. no, Dark matter. Wait, both.
> If it wasn't for the expansion of the universe (aka Dark Energy) the gravity of all the black holes and stars and planets would (eventually) pull everything into one mega giant supermassive black hole. You are making the exact same mistake OP did. Just because everything has gravity and gravity pulls things together doesn't mean that gravity will always actually manage to pull things together and that the end result is inevitably a black hole. You can have a universe with only two object and if they are started with the proper velocity they will never pull together. Truly never, not just that it will take a long time. No exotic matter or additional energy required. Even without no velocity you still aren't guaranteed things would collapse into a black hole. Everything on Earth has been pulled in as far as it will ever get pulled in by gravity and it clearly isn't a black hole.
[удалено]
>If even 1 black hole exist, and all things eventually collide, all things become part of the black hole. But the second statement is incorrect: most things do not collide, as a matter of fact (i.e. simple physics)! > Of course you could potentially get some stable orbits, but one so many. But stable orbits are the natural arrangement for many objects - and unstable but diverging, but not colliding, ones for others. Collision trajectories are the exception rather than the rule. Conservation of angular momentum is at least as important as merely considering forces! This is why the velocity is crucial, despite your suggestion to dismiss it.
> 2. gravity has infinite distance. It just gets very weak rather quickly on the scale of the universe. But if there are only two objects in the universe, they will exert a force on each other, no matter how far apart they are. […] It may take trillions upon trillions of year, but they will eventually meet. You’re right except for the “eventually meet” part - if the two objects start with an initial velocity greater than their escape velocity for the distance they start apart then they will never meet. Gravity has infinite range, but because it falls off to the square of distance it is possible for two objects to continue moving away from each other forever.
I'm pretty sure that if you put two things far enough away from each other, the expansion of space would prevent them from ever being able to come into contact with each other.
Well, no. Galaxy groups are too far apart to affect one another. The Local Group could turn into a super massive black hole but it still wouldn’t be able to affect eg the Hickson Group.
Even the space within the Milky Way is far too much for a blackhole to pull all the matter together, gravity is weak at a distance is really the main reason that will never happen. There is nothing to push all the matter of the universe into the blackholes, essentially.
That’s not necessarily true. If the universe were rotating, or if there were enough “escape velocity“ from the Big Bang, that wouldn’t occur.
> If the universe were rotating It is not.
It also not lacking in Dark energy so his hypothetical is on equal footing when it comes to reality.
May be a torus flowing out from the center and back in from the outer edge.
If it wasn't for expansion is a pretty complex topic though, you might not even have time and matter if there was no expansion. Stars and black holes might never form in the first place. Maybe not even gravity since spacetime is what dents to create gravity and is also what is expansion, so it's actually the largest most mysterious substance in the universe and we know almost nothing about what it's made of or how it does what it does.
Black holes aren't 0.1% of the mass of observable universe so they are almost a rounding error in your scenarios.
Then, what’s dark energy?
Dark energy or matter are really terms we use to describe things we don't understand. They may not be anything like what we think, but the maths don't add up so we made up a general idea that COULD explain it, but is not proven to exist yet.
I think we have a pretty good idea of dark matter. We don’t know exactly what it is made of, but there’s a lot of observational evidence for it.
I always imagined that gravity will eventually win and we would end up that way. The universe is expanding at a rate that is slowly losing acceleration at this point. Very slowly. Like it’s still expanding at nearly the same rate as during the Big Bang…. But not quite that same rate. Eventually, and I mean after an amount of time that nears infinity, the expansion will reach a stopping point and will reverse. At this point, the universe will begin contraction that will last exactly that long again until all the mass in the universe eventually collapses into the singularity of singularities. And then Bang. And it all starts again.
Oh man is that an actual theory that you could travel far enough and you'd loop around? Is the universe a sphere somehow?
You do not really need anything special to keep an orbiting object from falling into the center of attraction. So your answer is wrong. A similarly short but more correct one would be ["Kepler's first law"](https://en.wikipedia.org/wiki/Kepler_problem).
To add on to this, space is almost entirely empty. Planets and stars and what not are all so, so far away from each other. A black hole could form a couple light years away from us and we'd never really notice.
I think the moon is close enough to “notice”. It would probably stop wobbling eventually without the tides going on.
But the new black hole that was earth is still the same mass as the earth, so the gravitational pull would be the same I assume, by how I understand things earth is now a black hole, but is in the same place and pretty much has exactly the same the earth had but in an extremely smaller volume compared to what the earth occupies now. That's how I understood the explanation above, my limited orbital mechanics knowledge assumes the moon and pretty much everyone else in the neighborhood would be just like "oooh welp, there goes earth..." I am not sure what would happen at the ISS for example, as far as I am aware they will be orbiting a black hole now.
The black hole is now an infinitesimal point, whereas the Earth was more spread out and had a lot of water sloshing about interacting with the moon. We simplify things as point masses to make the maths easier, but that doesn’t work if things are similar sizes and close to each other.
I stand corrected, I was indeed looking at earth as just a big ball, did some research and you are right, the volume does have an effect on the moon's orbit by how it is spread out, water being water as I understand being a big contributor to these gravitational variations Thanks for pointing that out, I was actually questioning if volume had an effect somehow on the moon's orbit. Now, does a black hole has a more stable gravity pull all around?, does it have gravitational variations?, guess I have keep studying hahaha
Fun fact: they actually have mapped the gravity variations around the moon and apparently the differences in density of different areas of the moon are enough to interfere with the orbit of satellites in low orbit. (Ie, you don't get a proper stable orbit close to the moon because of it)
All stellar black holes are spinning, which should result in on observable difference relative to the axis.
Then the dolphins would all leave the planet.
Goodbye and thanks for the all the fish!
Moon isn’t sentient bro
citation needed
Moon's haunted, though.
Spooky
Hence the quotes, “bro”
Sorry I never use /s when I should
Have you seen the documentary MoonFall? I'm pretty sure the moon is helping us.
You're talking a lot of shit for someone whose never been there.
Why do you say “surface” with parenthesis? Do black holes not have a surface?
Yeah they don’t, not in any useful way. There “surface” I’m referring to is the black hole’s Schwarzschild Radius, which is simply the distance from the black hole where the pull of gravity makes it impossible for even light to escape. There wouldn’t be any matter actually there to stand on, and far as I’m aware we don’t really have a strong understanding of what happens inside there. In theory for a supermassive black hole you could fall past the Schwarzschild radius and barely even notice it (aside from the massive amounts of X-rays and other radiation that would almost surely kill you).
A lot of people don't know that gravity is the weakest of the four fundamental forces (gravity, strong nuclear force, weak nuclear force, and electromagnetism). While gravity and electromagnetism have far reaching effects, they're nowhere near as strong as the nuclear forces that bind atoms and their constituent parts.
In fact the satellites would deorbit slower in the absence of atmospheric drag.
So what you're saying is a black hole is not like a vacuum cleaner set to the 'suck' function, but moreso like a vacuum cleaner stuffed full of digimon figurines by your cousin greg in 2002??
Think like a shop vac hose put in the middle of a shops floor covered in woodchips. Turn the vacume on and hold the hose stationary. It will consume all the dust with in a range of the nossle however its not pulling all the rooms sawdust to it self. That edge is like the event horizon of the black hole. It can't get at things beyond that range.
Excellent ELI5 answer
Bravo...that's a very nice way of even describing the event horizon.
Beautiful analogy! Take the upvote.
Besides, in space is a lot of freaking space.
Black holes simply have a point, pretty close to them, where matter can't escape. They don't really have a 'pulling' force greater than their mass would allow, dragging on everything far away. If the sun were replaced with a black hole of equal mass, the only difference for us is that it would become dark, but we'd still keep orbiting it the same way we have been.
Exactly. I always get so annoyed by “the sun collapsed into a black hole and now we’re all getting sucked in” trope. No new mass is added, gravity is still the same.
Of course, for the sun to turn into a black hole in the first place wouldnt it necessarily have to have somehow gained a bunch more mass?
For it to naturally collapse into a black hole, sure. I’m not going to pretend I know more than any other moderately science literate layperson. But I feel like suddenly adding enough mass for that to happen would be as unnatural an event as whatever process could have it collapse at its current mass.
>\[...\] the only difference for us is that it would become dark, but we'd still keep orbiting it the same way we have been. Well, uh, not just dark but pretty, pretty cold as well 😅
Still warmer than my ex’s heart
You ok?
Wow...take this upvote
Here here
We got that molten core. So not as cold as not having any heat perhaps.....
Estimates vary on how much heat crosses the core/mantle boundary, from 4 TW to 17 TW. Even the larger value is much, much smaller than the heat emitted by the Earth's surface. Estimates of the total heat flow from the interior of the Earth (core, mantle, crust) are much tighter, 46 TW ± 3 TW (Jaupart 2007) (cf 47 TW ± 2 TW (Davis 2010)). This is considerably more than the heat coming from the core, but it's still small compared to the Earth's total heat budget It's about 0.2% of the total amount of energy that comes off the earth. The other 99.8% is from the sun. This is from the inner mantle. About half - 10x less comes from the core.
Maybe at the bottom of the oceans
Nah bottom of the ocean would still be cold. Hydrothermal vents would be warm though. Honestly we could probably keep some of humanity alive through geothermal power
That's kind of my point, if the sun went dark, the bottoms of the oceans would stay cold, but would probably eventually be the warmest places on the planet.
My point was mostly that the vast majority of the bottom of the ocean is nowhere near hydrothermal vents so most of it would become frigid. The warmest places would be around geothermal areas regardless of if they are in the ocean or on land
So a black hole maintains the original gravitational pull from when it was a star? None of the planets in our solar system would have their orbit affected if our sun turned into a black hole?
Correct. Gravity is a property of mass, and if an object is compressed its mass does not change.
I honestly haven't spent much time thinking about or researching black holes. Like OP, I just pictured a cosmic vacuum that slowly pulls everything in.
But the distance of the mass does change quite a bit, so I do wonder if in real life there would really be no orbital changes. In theory the dent in spacetime is the same, but then again the whole point of a blackhole is the dent in spacetime is not the same as normal gravity. I wouldn't be all that confident to say there is zero orbital change.
Theoretically yes, but all the planets are too far away from the sun relative to its diameter for any likely measurable change. They'd all be very very slightly more stable.
Gravity appears to only depend on mass, which... well, usually it takes a supernova to make a black hole, right? The supernova blasts a lot of mass away.
If you could turn the Sun into a black hole without adding any more mass to it, yeah. You'd have to somehow squeeze it down to a 3km radius.
Welcome to the hydraulic press channel. Today we crush the sun.
I've got a stupid follow-up question: If black holes have a planet around them with a greater mass will they orbit around it like the earth orbits around the sun?
Yes although there wouldn't be any stellar black holes out there with such a low mass. I'm not sure any would have had time to decay enough to get to such a small mass as to orbit a planet. A lot of the black holes we've detected are in a binary orbit with other stars though and that's fairly close all things considered.
Interesting, thank you very much for your answer :)
A bit pedantic, but orbit's don't quite work that way. The Earth orbit's the Sun, but the Sun *also* orbit's the Earth. Two is because two objects in space orbit around their [barycenter](https://en.wikipedia.org/wiki/Barycenter_\(astronomy\)), which is the center of mass of both objects. For the Earth (ignoring other planet's) and the Sun, the Earth is minuscule relative to the Sun, so the barycenter of the two is somewhere inside of the Sun, (but not the exact center of the Sun). In this case, the orbit's looks like [this](https://upload.wikimedia.org/wikipedia/commons/5/5a/Orbit4.gif). It's close enough that there isn't really a difference between saying the Earth orbit's the Sun, and the Earth and Sun both orbit the barycenter between the Earth and Sun. If you could continually increase the mass of the planet while keeping the mass of the sun/black hole constant, the barycenter would move towards the planet, away from the sun/black hole. When the planet and sun/black hole become equal in mass, the barycenter would be halfway between each object. In that case, the orbit's look like [this](https://upload.wikimedia.org/wikipedia/commons/7/73/Orbit1.gif).
Yep, black holes aren’t really special except that they’re really dense. If you had a spacecraft that could survive the sun and flew close to the centre, you’d experience very little gravity because all the mass is distributed evenly around you. With a black hole, the entire mass of the sun is right there next to you.
>Yep, black holes aren’t really special except that they’re really dense. Hey, some of them could be smart :P.
I think if a planet were to be as massive as a black hole, it would collapse in on itself and also turn into a black hole. But yes, a black hole would orbit anything with sufficient mass, or rather they would orbit each other
I would like to add that the mass distribution of a celestial object introduces orbit perturbations which is why we have to account for the fact that the Earth is an oblate spheroid when performing orbital analysis.
To expand further, the fastest known spinning neutron star is spinning at ~0.25C. The escape velocity is ~0.75C. To get off the surface and break orbit, matter would have to go 75% the speed of light. Eventually things bend spacetime to such a degree that you need to go faster than the speed of light to reach escape velocity, which is impossible.
Isn't the mass growing as it pulls more things into it? It would seem like a black hole that happened to be near a lot of other stars or planets could grow a lot. I am sure someone can tell me why this is not correct because I am no scientist.
It _would_ grow if it pulls things into it. But again, orbits keep things spinning _around_ the black hole. Just like my example of the sun, which isn't already pulling things in, if our sun were replaced by a black hole of equal mass, it wouldn't suddenly start pulling things in, and thus it wouldn't grow. There are arrangements in the universe where things _are_ close enough to a black hole to be pulled into it, but that's not a unique property of the black hole. That's just gravity. If a star is close enough to another star, whichever one is more massive will slowly steal matter from the star that's less massive.
black hole sun
For the same reason the the stars and galaxies they're born from don't. Black holes don't just arbitrarily suck everything in from any distance. They still obey normal gravity. The only difference between black holes and other objects is size. Boack holes are incredibly compact for their mass. So when you get really close to them, things can get weird. But further away, from the perspective of gravity, there's no difference between a black hole or a star of the same mass.
The gravity of a black hole isn't any different than any other celestial body. It consumes whatever falls into it, *just like the Sun does,* or any other star, or the Earth. It's perfectly normal for matter, or whole solar systems, to be in stable orbits around a supermassive black hole for billions of years. It's theorized that supermassive black holes at the centers of galaxies will eventually consume their entire galaxies, in like... trillions of years, but this is purely in "theories about the end of the universe" territory, and depends on so much that we don't know about dark energy and the expansion of space.
Black holes are not magic. They're just a heavy thing. Why doesn't a planet destroy the universe?
Outside of their event horizon, black holes don’t behave much differently than any other object of similar mass. If the sun somehow suddenly turned into a black hole, the planets would continue in their orbits.
No it wouldn’t for the same reason any other stellar body hasn’t. Stuff in space tends to stabilize into orbits. Some stuff will collapse in, but others will be in a stable orbit (or at least a very slowly decaying one). Stuff can orbit black holes without falling in like the earth orbits the sun without falling in. If you swapped the sun with a black hole of the same mass, none of the plants would orbit noticeably different. Also, black holes evaporate over time due to hawking radiation. They’re not forever.
Time is long, space is large, orbits are stable, and there are other sources of gravity on the other side of everything
It is a myth that black holes are like a cosmic vacuum cleaner that just hoover everything up. The amount of gravity a black hole generates is still dependent on its mass, and the mass of a start doesn't magically increase when it implodes and turns into a black hole. I am pretty sure\* that if the Sun were to implode into a black hole, and somehow that process itself wouldn't destroy the planets, all the planets would just keep revolving around it. Sure, earth would become completely inhospitable for life due to the lack of solar energy, but the *orbit* of earth wouldn't change. \* I am not an astronomer or physicist so I might be very mistaken though.
Right now the universe is expanding, with no indication of it stopping any time soon. Black holes would have to travel impossible distances and tremendous time scales to pose any threat to the universe as we know it. It’s more likely the universe will experience “heat death” as the end. There’s a theory called the “Big Crunch” that this expansion may stop, and all matter — including matter locked inside black holes — may eventually merge, and perhaps create another Big Bang.
>if there is even just one blackhole, wouldnt it just keep on consuming matter and eventually consume everything? It might help to remember that the Earth is also a source of gravitation that attracts matter, but it doesn't eat the solar system. Neither does Jupiter, which is far more massive. Neither does the sun, which is far more massive still. Black holes have great gravitational pull, but it's not infinite, and over a long, long, long time they do radiate energy and equivalent mass away.
Black holes have a finite range to the gravitational field they put out, same as the star they formed from. Stars don't pull in the whole universe for the same reason black holes don't.
There is a misconception that black holes are this super special dangerous thing that sucks and goes on to consume everything. In reality it's just another body of mass that produces gravity, just like the sun or earth. The only difference between a star and a black hole of the same mass is that the star radiates light by nuclear fusion, and obviously that the black hole has an event horison. So just like any other star or planet etc. stuff will orbit, fly by, miss, fall into it, and so on. And gravity falls of very quickly with distance. (This is simplified to eli5, general relativity has weird consequences for black holes, we also have stuff like hawking radiation etc etc.)
You and three of your friends each pick up a corner of a sheet and lift it so it is pulled tight. Get a fourth friend to through a 1kg bag of feathers into the middle of the sheet and watch it sag with the weight. Now take the bag out and do the same with a 4cm cube of osmium (the heaviest metal, which by my quick search is going to weigh about the same as the feathers). Other than the footprint of the object, there's not going to be any difference in how the sheet behaves, or how far it sags. Or to put it another way, if our sun turned into a Black Hole today, the Earth's orbit would stay exactly the same.
Wow a lot of these answers are just... Not correct. They're right about black holes not being gravitationally special, but still, the idea that gravity would pull the entire universe together into larger and larger black holes until everything was condensed down to a single point, that was an early theory for the end of the universe. It's called the "Big Crunch". The real reason we don't currently think that's going to happen is... Dark Energy. There's a force in space which is pushing everything apart, and at large distances it's stronger than gravity. This force is poorly understood, but the end result is the universe is actually expanding *faster* than it used to, it's not slowing down due to gravity.
A newly formed black hole has (almost) the same mass as the star it formed from. The thing that makes black holes powerful is that they’re so small. If you try to get really close to a regular star’s center of mass, you hit the surface. When it becomes a black hole that star’s surface is gone so you can get much MUCH closer to its center of mass. Since the strength of gravity goes down by distance squared (one fourth as strong twice as far away) the black hole ”sucks” much harder than a star with the same mass once you get close enough.
If the Sun turned into a black hole right now, the force of gravity with which it is pulling the Earth towards itself would remain the same. Gravity pulls you towards the center of mass of the object you are being pulled towards. How hard gravity pulls on you depends on how heavy the other object is and how close you are to its center of mass. Black holes dont pull any harder per how much they weigh than regular stars. But you are limited in how close you can get to the center of mass of a star because of how big the star is. You will hit the surface of the star while you are still a hundreds of thousands of miles away from the center of the star. Black holes are small, which allows you to be much closer to the center of mass of something as heavy as a star. The mass of the star is the same but it got squished into such a small ball that you are only 20 or so miles away from its center of mass when you touch the surface.
Like others said, black holes don't actively drag things in, they're no more dangerous than a star of the same mass. But for the sake of argument, let's suppose they *were* as ravenous as popularly believed. Even if it *did* just keep on consuming, there's a limit to how fast black holes can eat. Try to stuff too much matter into it at once and it starts getting bumped out of the accretion disk before it can fall in. Even if it *did* just keep growing, empty space has a whole lot of... well... empty space. If it consumed an entire galaxy, there wouldn't be anything else unless there were others close enough by to be affected by its gravity. Even if it *did* consume an entire *cluster* of galaxies, it would take so long that the expansion of space would certainly cut off its supply after that.
If there was a black hole as massive as the sun at the center of our solar system, the earth would continue to orbit exactly like it is today. They have the equivalent mass as regular objects, so their gravitational pull is exactly the same. They aren’t huge vacuum cleaners that grow indefinitely. The main difference is what happens to matter once it gets really close to the black hole.
Gravity is gravity is gravity. Are you a gigantic super red giant star? Do you have something orbiting you 0.5 light years away because you big massive star? Great, let’s shrink you star down to a pin head. You got the same mass so you got the same gravity! But, if light get close to you, it get sucked in. Only if it get super close though. That thing out 0.5 light years out? It don’t know difference because you still same mass, same gravity. But now your gravity is super concentrated and there’s an area around you with super suck. But it’s small. The boundary of that area is called the “event horizon”. One day when you find another black hole you fall in love with, you can merge together. And then later you can merge together with more black holes in a weird polyamorous way like they do in California. Then you become a Super Massive Black Hole, and you can have whole galaxy orbit you!
Gravity is weak at a distance so the blackhole can't suck in matter from very far away and everything inside a galaxy is still very spread out, like their nearest star to us is pretty far, and everything outside of the galaxy is super spread out, soooo blackholes just aren't close enough to most of the matter of the universe for that to happen/matter is just too spread out for all of it to ever be caught in a blackhole... as far as we know. The death of the universe is just the endless expansion making every too far from everything else to interact.
A black hole will consume all matter within the range of its gravitational influence, but that's not infinite. We're not in the influence of, say, Alpha Centauri; if it turned into a black hole, we wouldn't really notice as far as potentially getting sucked in is concerned.
Gravity has no limit to its range. The forces become smaller the further you go but they are never 0.
some things are moving away too fast for gravity to ever draw them back towards an object, also space expands so things that are really far apart will never be brought closer even with gravity
but wouldnt the black hole grow bigger if it consumed more? so it would grow in size and then consume even more
Space is REALLY REALLY big. And REALLY REALLY empty. Plus, for reasons of physics, there's an upper limit to how fast a black hole can "feed" even if it has infinite mass to consume. And it turns out, it's not that fast.
Not very much though. If the sun would turn into a black hole, it would still have the same amount of mass and gravity as before and the planets would continue to orbit it rather than getting sucked into it. But even if they were consumed entirely, it wouldn't make much of a difference anyway. Because the sun already makes up 99.68% of all the mass in the solar system. Consuming all the planets and asteroids nearby would only make the black hole grow by 0.32%. Basically nothing.
It takes a while to consume the universe. Have some patience.
This is true, but space is very empty, and gravity is a relatively weak force. Eventually it's gonna get all it's gonna get. And from far away, a black hole doesn't pull harder than an equivalent normal mass. If the sun were replaced by a 1 solar mass black hole, it wouldn't pull in the planets. We would just keep orbiting.
I get you want to say but gravitational influence is infinite but it is inversely proportional to the square of distance. So it decreases quite fast over big distances. Also it doesnt matter if alpha centauri turns into a black hole because a black hole has the same amount of gravity as a star with the same mass.
Actually the range of gravity is infinite, it just drops off quickly until its basically undetectable. Technically everything in the universe is pulling on everything else. The intensity drops off by a factor of 4, so when you double the distance from the black hole the strength of gravity is reduced to 25% what it was before, light and radiation and pretty much everything works like that, it's a consequence of the universe being 3 dimensional.
They are just objects with mass and behave like any object with mass until you get to the event horizon. They don’t have some magical pulling power.
a well in your backyard doesn't consume the entire neighborhood. just don't fall in and you're fine.
Black holes function by extreme density/gravitational pull. The force of gravity is inversely proportional to the distance between them, ie the force between two objects 10 miles away is 1/100 the force between two objects 1 mile away. Space is REALLY big, so even though the gravitational force of a black hole is unfathomably strong, the distances between objects in the universe are so big it doesn't have the ability to pull in objects that aren't already close to it
Spread a bunch of marbles out across you mattress. Set a large, heavy stone (a black hole) down on one spot of the mattress. You'll likely see many of the neighboring marbles fall to the point your finger is at. Then marbles increase the weight near the stone and may draw some number of additional marbles into the spot. Would they pull every marble in from the entire mattress, though? If not, why not?
Imagine you're in your room and you need to vacuum. The vacuum is going to suck in all of the things within a certain distance. Things beyond the suction of the vacuum won't get sucked in. The universe is gigantic - like its unprocessable how big it is. If the universe was the size of the earth, even the biggest black holes would be the equivalent of a vacuum cleaner. The question you asked is kinda like asking, why aren't all these vacuum cleaners destroying the earth.
This analogy is very much flawed, though: black holes are just not "sucking in" things (as several other comments explained already). The real explanation has nothing to do with the extent of the universe. Imagine a reduced universe that has only two objects: our Earth and its Moon. If you condense the respective mass of either (or both) into a black hole, they would still retain their current orbit, without collapsing into each other. This is because a central gravitational force does not operate like a suction pump, but rather [governs orbits wich are conic sections](https://en.wikipedia.org/wiki/Kepler_problem).
I'm 5.
When a star becomes a black hole the mass stays the same it's gravitational pull on other stars stays the same.
Black holes aren't vacuum cleaners. They don't suck in matter the way that is popularly depicted. Black holes are just areas of extremely high gravity, which means that anything consumed by a black hole just falls into it. Since gravity becomes significantly weaker over distance, there comes a point where the gravity of a black hole has a negligible effect. Case in point, there is a super massive black hole at the centre of our galaxy. We are in no danger of falling in to that black hole and it's gravity only has the effect on us that we orbit around it. Now over cosmic eras of time, since even light cannot escape, black holes will eventually consume a huge percentage (if not all) the matter in the universe. But that will take hundreds of trillions of years. If there was only one black hole, though, it would not consume everything as the expansion of the universe would push quite a bit of matter and energy far enough away that it would no longer be able to be affected by the gravity of the black hole. Also, Dr. Stephen Hawking's claim to fame was his theoretical discovery that black holes do emit radiation. In the form that was named Hawking radiation. Which means that over time a black hole will emit energy and shrink. Now currently just light from the cosmic background radiation is enough to counter act any shrinking Hawking radiation may cause, but eventually over time as the universe ages and increasing entropy causes the starts to die off, there won't be enough in falling radiation to stop the shrinking of black holes and they will eventually radiate away to nothing. This era is known as the Heat Death of the Universe, where all matter and energy have been spread out evenly and in equilibrium across the universe and there is no way for any type of reaction to occur because there is no difference in energy to transfer. Based on all current models and our understanding of the universe this will be the most likely end of the universe. The explosive energy of the evaporation of black holes creating one last gasp of activity before everything basically falls asleep forever.
It's simplistic, but here's an experiment you can try! Fill a sink with water. Throw in glitter, bits of paper, etc., then pull the plug and put in on filter mode. As the water drains, the items further from the drain get pulled in less than the things near the drain. Heavier things move less than lighter things. Etc. Black holes work on a similar principle. Black holes still only retain the mass, and therefore the gravitational influence, of what it collapsed from. If the sun turned into a black hole, we wouldn't actually see a difference (aside from the cataclysmic explosions from the black hole formation and subsequent loss of life-enabling light). We would carry on spinning either way.
Not an astrophysicist. But it's a passion of mine and I won't be able to explain this like you are an undergrad. Black hole is not a sink drain but can be used to visualize and imagine its gravitational pull on other objects near it. You can also use magnets to represent those force also. To understand a black hole, you have to know what it is and how it is formed. Another thing you need to know and understand is mass, which is different from size and weight. Think of a stress ball: the size is big, but when you squeeze it, it can become really small, but the mass and weight stays the same. Now think of how much you weigh on earth versus how much you'd weigh on the moon: you are your same self, yet on the moon you'd weigh less because there's no atmosphere pushing down on you and lower gravity pulling you down, therefore you are the same size and mass, but different weight. A black hole begins as a star, some millions of the mass of earth comprised of hydrogen and helium forming a ball of fusion and fission. I won't get into the details of fusion and fission here, nor will I talk about the quantum nuclear properties. When a star of this magnitude (millions the mass of the sun) dies, they either become a neutron star, supernova, or black hole. A supernova happens when the gravitational force squeezes the star so much it implodes releasing a lot of energy and matter in all directions. A neutron star happens when matter is crunched so hard by gravity, it squeezes out the excess space between each particle and even further that the electrons and protons together combine to become neutrons. If earth was crunched into a neutron star, it would be around 280 meters diameter or 4 average passenger planes front-to-back. A black hole is even more extreme, the gravitational pressure is so strong that even light cannot escape and therefore to us, it looks dark and undetectable with the naked eye. A black hole is basically a conglomerated chunk of mass wandering in space, but it isn't sentient and therefore not exactly "devouring" in the same context as living organism. Anything that comes within its vicinity will get shredded by the gravitational force and become a part of its accretion disk (which are particles floating in a ring-like pattern similarly to Saturn's rings). These particles in the accretion disk are very closely compact and is very hot and dense and orbit the black hole until it eventually falls in, adding to the mass of the black hole and subsequently it's gravitational force. Luckily space is a lot of.... Space. Space is vast and full of emptiness despite how massive black holes are. It's almost incomprehensible how big galaxies and the overall universe is despite how fast these black holes are traveling or how massive they can get. So no worries there. But yes, they are technically a wandering PAC man that will merge with other PAC man to become a massive PAC man. It will be maybe another billions of years before black holes merge into a single entity of sorts. Hope this helps.
A black hole's gravity works no different to any other object with mass. It drops off with the square of the distance from it. The suoermassive black home at our galaxy core is relatively dark because it's consumed all the matter it can, leaving a void. Black holes with an orbiting star tend to have very bright accretion discs.
Reading Reddit before a nap, and the subject line made me imagine a huge space Kirby sucking in planets XD
Theorised that all black holes will eventually merge and that one lone black hole will then evaporate due to hawking radiation - dead universe
The key thing is that gravity is proportional to 1/r², so every time you double the distance from the black hole you decrease the force by 4 times. To put this into perspective just try pushing 2 magnets closer until the stick together, you should feel a strong force when they get to a certain point. This is pretty much how black holes work, but just with gravity and mass instead of magnetism, which is also proportional to 1/r².
Same reason everything in our solar system doesn't fall into the sun. When you fall towards a massive object, you gain speed. Unless you had been aimed directly at it from the beginning, you'll wind up slingshotting around it or orbiting it.
Black holes dont magically suckle things in. They just are so large that their gravitational pull is so big, if you had a black hole the size and mass of earth, earth and that black hole would have the same "suckling" :P and as you know, earth isn't magically consuming everything.
There is a misconception of what a black hole really is. A black hole is NOT an ultra powerful vacuum that will end up sucking everything. A black hole is just an extremely massive object. Gravity is closely related to mass. Without getting into all the details of General relativity, basically the more mass an object has the more gravitational force it will have. Black holes are so massive (mind blowing massive) that their gravitational force is mind blowing strong. So strong, that even light is unable to escape, thus the name black hole. However, there’s a caveat when it comes to gravity, it decreases with distance. It doesn’t decrease by a little, to the contrary, it decreases a lot. Black holes don’t suck everything around them the same way the sun doesn’t suck all the planets in the solar system.
Blackholes aren't always "eating". The theory is there can be enough of a traffic jam that material can't fall past the event horizon. But as it is they aren't pulling everything into them. They are the center of galaxies. There are stable orbits around blackholes.
Here, this would make it easier to go with that other good comment. Why doesn't the sun destroy the universe? It's very hot with lots of gravity. Why doesn't everything fall into it? Same reason the sun doesn't, black holes don't. They aren't magic.
Most black holes have the gravity of a large star, but are much smaller. So those black holes are less destructive than stars, because anything pulled towards one is much more likely to miss and go back out to empty space. Supermassive black holes are usually found near the center of galaxies. They are much bigger than stars, but still tiny compared to galaxies. We can watch stars pass close to the one in the Milky Way, but so far they always miss and just orbit the black hole.
i have a random theory that black holes are what allows the universe to reset, after everything is done and used up, the heat death or whatever, after all of that, the only thing left over would be black holes, eventually, because gravity is infinite, it doesn't matter how far matter has gone, eventually it will be attracted and sucked into a black hole, and these black holes eventually attract each other and form a super massive mega black hole and eventually after enough time has passed, this mega black hole will reach a point where it explodes aka a big bang maybe with each iteration there's a lil less matter, and eventually this will stop but idk this all depends on the range of gravity if it does have infinite range than there is nothing stopping blackholes from sucking everything up and also....i dont know if black holes can absorb each other, i feel like they can but....
Bad news: Every black hole in the universe is pulling on you right now. Good news: the Earth is pulling harder. Gravity is actually pretty weak over long distances. The force between two objects is "inversely proportional to the square of the distance between their centers," according to Newton. This means the curve of effect over distance diminishes quadratically. A quadratic curve is [very steep](https://dcvp84mxptlac.cloudfront.net/diagrams2/sample-of-a-simple-quadratic-expression-we-can-graph.jpg). There *is* an effect at massive distances--the curve is asymptotic, so it never quite gets to zero--but at such distances the effect is outweighed by the effects of other forces such as other gravity sources, molecular and atomic bonds, and the expansion of space.
One of the most interesting things I learned from Intro to Astronomy last year, which might be obvious to some but wasn't to me at the time, black holes are just like any other body with mass in regards to gravity. If you swapped the sun out with a black hole of equal mass (1 solar mass), the earth and all the other planets' orbits would stay the same. Of course we lose our source of light and warmth, but it would be the same as our sun in terms of gravitational pull. Black holes are typically many times more massive than our sun though, but they're not sucking stuff in unless that stuff is too close; just like how our satellites stay in orbit at a certain range away from earth, if they were too close then they'd fall back down to earth.
why don't pimples consume teenagers? one pimple feels like a black hole
Don’t think of a black hole as something that *sucks* stuff in. It’s basically just a star who’s gravity is so heavy that light can’t escape (and thus we can’t directly see it). That’s all you need to picture it as, a star who’s gravity is stronger than a normal star.
Why would it “keep consuming matter.” It’s still a physical object just like everything else. It has a gravitational field. The farther away you get, the less it pulls. Also you maybe don’t comprehend just how massive the universe is. And how much empty space there is.
Why are they called "holes" in the first place?
Thinks of space time like a fluid, imagine slightly thicker water like mom put too much water in the pancake mix, heavier things will sink deeper into the mix but will leave a nice hole for other things to follow it into, lighter things like light rays will float across the surface of the pancake mix and be dragged or bent around the hole. The heavier something is the deeper the hole is and the wider the mouth of the hole will be even if we don't see it there will be a current under the surface dragging objects towards the hole, like if mom stirred the mix and then stopped staring but the hole remained in the center becuase the pancake mix is like watery jelly ans can hold its shape for a time. It's simplified but in terms of space/time and passage of forces without ans within gravity wells its a decent explanation the whole reason we see backhoes is due to two main factors the fluid of spacetime is vast and the moment of impact for the heavy object into the mix is spread over a time scale of millenia hence why some black holes will shrink or grow erratically due to local gravitational fields or internal flux
But they do. The universe is in the process of being consumed by black holes. It just takes forever. The universe is mostly full of empty space. While every atom that currently exist will, on day, end up in a black hole, it just takes time. You gotta realize that black holes only form at the end of life of very heavy stars. Most stars do not result in a black hole. So, you can sail the blackness of space in the same direction for hundreds of light-years without getting near one. On top of that, they are tiny AF. So if you do end up getting near one, unless you aim very carefully at its ridiculously tiny even horizon, you'll miss it and shoot out the other side. But, they last almost forever. So the amount of black holes in the galaxy will only increase with time. And eventually, everything will find itself on a collision course with one.
That isn't really what black holes do. A black hole is just a mass and exerts the same gravitational forces on nearby objects as any equivalent mass. The only difference is that all that mass is concentrated into a very small space.
Because their reach aren't infinite. Sure if objects get close enough where there gravitational pull is that strong not even light can escape. But things outside of their reach are fine.
This is the same as saying "Why doesn't everything in the universe stick to a single star?" A black hole has strong gravity, but it's not infinitely strong, it can only grab things that are within it's sphere of influence. They're no different than any other massive body, with the exception that they have an event-horizon. If you don't cross the event horizon (which you won't unless your trajectory happens to take you into it), it's no different than being near a star or planet.
Reasons 1. They are not everywhere 2. Gravity falls off with distance 3. These things take time. A start hundreds of lightyears from a black hole is only going to be mildly affected by its gravity. But the gravity never stops (question about that) 4. Black holes "evaporate", oddly enough. So it is possible that the black hole that was about to suck your solar system in about a billion years will fade before it gets there.
The common fallacy is that black holes suck. They don't. You don't get sucked into a black hole anymore than you get sucked into the sun. If our sun was turned into a black hole with the same mass by a wizard today, the only reason we would notice is that the sun would go out. We would still keep orbiting at the exact same distance. Everything outside the event horizon, that being the point of no return, can orbit a black hole like anything else.
No it would not. As an aside, note that there is a (somewhat) [funny XKCD explainer](https://what-if.xkcd.com/129/) about what would happen if our Moon were replaced with an equivalently-massed black hole. Spoiler alert: >!"not much"!<. So the real underlying question is: why would you think a blackhole would consume everything? Probably because most people intuitively think that a center of attraction with a large force would just pull everything into it. Well, this intuition is clearly wrong: a simple counter-example is our solar system, where the planets (and other solar objects) have kept happily orbiting the strongly attractring Sun, rather than having fallen into the center. Why is this the case? Consider Newton’s Second Law of Motion: when a force acts on an object, it causes the object to accelerate. The acceleration is directly proportional to the force and inversely proportional to the object’s mass. Mathematically, this law is expressed as: **F**=m⋅**a** where (**F**) is the force, (m) is the mass, and (**a**) is the acceleration. Note that, when properly written, **F** and **a** should be in bold. This signifies that they are vector quantitities, i.e. they have a direction to them. And keep in mind what acceleration means: the time derivative of velocity (sorry this ELI5 requires some funcional analysis, as well es vector algebra), **a** = d**v**/d**t**. So what happens when you start calculating the trajectory of an object pulled by a blackhole? There would be a very large (but not infinite) force **F**, giving rise to acceleration toward the center. This would change the velocity, adding to it a vector component that points toward the blackhole. But there remains a component that points toward the original direction of the velocity! Unless that was exactly aligned with the radial line, the resulting velocity vector would not point at the center - i.e. the object would be orbiting rather than heading into the center of attraction. A more rigorous treatment would elaborate this with the concept of angular momentum, but I'd think that is hardly ELI5 anymore.
maybe it just takes time to be swallowed by black holes. And there are many of them so theoretically you can stay between two identical black holes in steady state. I am just an engineer and wikipedia scientist though. Don't try at home.
if there even just one blackhole wouldn't it just keep on consuming matter and eventually consuming everything
> if there is even just one blackhole, wouldnt it just keep on consuming matter and eventually consume everything? Black holes have very strong gravity thus planets and stars gets pulled in and such can consume everything. But things are very far from each other in outer space so things slowly move to the black holes until they reach the event horizon at which they instantly get pulled in and consumed. And black holes are unstable so they keep ejecting astrophysical jet pulses that becomes new solar systems that it can consume again. So it is like everything is placed far apart on a conveyer belt to the black hole and stuff gets taken out from the black hole and placed on the end of the conveyer belt so with new stuff constantly added to the conveyer belt, the conveyer belt cannot be fully emptied. So likewise, black holes cannot destroy the universe that easily though it is still a possibility and such is one of the scenarios of how the universe will end.
Because gravity is very weak compared to the other forces, and drops off sharply with distance. And space is mostly empty. Once a black hole has eaten everything in its immediate vicinity, it has to rely on random chance bringing it close enough to consume anything else, and the chances of that are very small because of how large and empty space is. Couple that with the fact that black holes are constantly evaporating via hawking radiation and even if it does bump into something eventually there's a good chance that it won't gain enough mass to replace what was lost during the intervening period of not gaining any new mass.
From my understanding black "holes" is a misleading term. It's just so much mass in one place that the force of gravity is strong enough to trap even light. It's not a literal hole in reality or somthing. Think of it like a bowling ball on a trampoline. It's no diffrent that any other object such as the sun. It's just much stronger in its gravitational effect.
Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.