<p>In outer space, a vacuum isn't what sucks in matter to a black hole. That may be the case for your household vacuum cleaner, but everywhere in outer space is essentially a vacuum. Instead, it's the black hole's powerful gravitational pull.</p>

<p>However, black hole can have energy. One type that comes to mind is <em>angular kinetic energy</em>. This is the energy that a spinning object has - in this case, a <a href="https://en.wikipedia.org/wiki/Rotating_black_hole" rel="noreferrer">rotating black hole</a> (see also <a href="https://en.wikipedia.org/wiki/Kerr_metric" rel="noreferrer">Kerr black hole</a> and <a href="https://en.wikipedia.org/wiki/Kerr%E2%80%93Newman_metric" rel="noreferrer">Kerr-Newman black hole</a>). Black holes can also have <em>translational kinetic energy</em> - the energy of an object in motion. Also black holes have gravitational potential energy - potential energy due to gravity - and <a href="https://en.wikipedia.org/wiki/Reissner%E2%80%93Nordstr%C3%B6m_metric" rel="noreferrer">black holes with electric charge</a> can have electric potential energy.</p>

<p>So black holes do have energy, although perhaps not in the form you thought.</p>

<p>Keep asking good questions!</p>

<p>I hope this helps.</p>

CC BY-SA 3.0
2014-10-09T00:21:01.250Z
2014-10-09T00:21:01.250Z
HDE 226868
<p>The only way we can detect black holes is through the effect that their gravitating mass has on objects outside the event horizon. These objects can gain energy from the black hole, as they fall into the potential well they heat up and radiate (often in the X-ray region of the spectrum). So black holes have gravitational energy from their mass. A black hole could also have charge, but this is rare in the universe which is largely neutral. Many black holes probably rotate, and these also have rotational energy.</p>

<p><a href="http://curious.astro.cornell.edu/disclaimer/86-the-universe/black-holes-and-quasars/general-questions/436-what-type-of-energy-does-a-black-hole-have-intermediate" rel="nofollow noreferrer">http://curious.astro.cornell.edu/disclaimer/86-the-universe/black-holes-and-quasars/general-questions/436-what-type-of-energy-does-a-black-hole-have-intermediate</a></p>

CC BY-SA 4.0
2018-10-10T03:47:34.453Z
2018-10-10T03:47:34.453Z
NoWar
<p>The principle of conservation of energy tells us that the amount of energy in the universe is constant. Therefore we can conclude the energy that once made up a star that turned into a black hole cannot be destroyed. So yes according to the principle of conservation of energy a black hole contains energy. </p>

CC BY-SA 3.0
2016-03-31T10:41:52.113Z
Conservation of energy on a universal scale is not a given and is not required by General relativity.
ProfRob
CC BY-SA 3.0
2016-03-31T07:39:55.883Z
2016-03-31T07:39:55.883Z
Connor your friend
<p>An isolated black hole is a vacuum solution of general relativity, so in a very direct sense it does not contain any energy anywhere in spacetime. But perhaps somewhat counter-intuitively, that does not imply that such a black hole has no energy.</p>

<p>Defining the total amount of energy is usually very problematic in general relativity, but in some special cases it is possible. In particular, the usual black hole solutions are all asymptotically flat, i.e., spacetime is just the usual flat Minkowski when far away from the black hole.</p>

<p>Here (or in general when we have a prescribed asymptotic form of the spacetime), we can calculate the total energy-momentum, by essentially measuring the gravitational field of the black hole at infinity. The energy just be one component of energy-momentum. </p>

<p>There are actually two relevant different kinds of 'infinity' here: spatial infinity and null (lightlike) infinity, depending on whether we are 'far away' from the black hole in a spacelike or lightlike direction. There's also timelike infinity, but that just corresponds to waiting an arbitrarily long time, so it's not relevant here. The two different infinities beget different definitions of energy-momentum, giving the the <strong>ADM energy</strong> and the <strong>Bondi energy</strong>, respectively. In a vacuum, the intuitive difference between the two is that Bondi energy excludes gravitational waves.</p>

<p>So the short answer is 'yes', with the caveat that in a more complicated situation, where we can't attribute everything to the black hole itself, the answer to <em>how much</em> energy is due to the black hole may be ambiguous or ill-defined.</p>

<p>Note that the ADM and Bondi energy-momenta also define their corresponding measures of <strong>mass</strong>, as the norm of those energy-momenta ($m^2 = E^2-p^2$), but for a black hole we can also define mass more operationally in terms of orbits around the black hole. There are also other alternatives for addressing mass specifically.</p>

CC BY-SA 3.0
2014-10-09T01:08:21.637Z
2014-10-09T01:08:21.637Z
Stan Liou
<p>So black holes are created by certain dying stars and when the star runs out of nuclear energy gravity wins out and the star implodes. An entire star’s mass collapses down into a smaller and smaller volume of space. Which then creates a black hole, so my question is, do black holes actually have energy to create that type of vacuum to suck light in?</p>

<p>If a black hole was created by a huge star running out of fuel and then collapsing in on it self, would the black hole have energy and if so where would it come from, or is it just like the vacuum in space with no energy at all?</p>

<p>(Please correct me if I said anything wrong about the black holes as I am very young and don't quiet grasp the concept of it yet.)</p>

CC BY-SA 3.0
2017-04-20T17:48:01.900Z
If I'm reading your question right, you're asking if gravity requires energy.    If the "sucking" requires an energy source and where does gravity's "sucking" energy come from.    I'm pretty sure this has been asked before.  In a nutshell, A massive object with gravity in and of itself has no "sucking" energy.   If you have 2 objects, a heavy body and a smaller body some distance away, the 2 body system has potential energy, And the potential energy can explain the object falling towards a black hole.   That's an oversimplified version of Stan Liu's post - just thought I'd put it out there.
userLTK
CC BY-SA 3.0
2017-04-20T17:55:29.783Z
Two related questions on gravity and energy:  https://physics.stackexchange.com/questions/75222/where-does-gravity-get-its-energy-from  and  https://physics.stackexchange.com/questions/7118/is-gravity-energy
userLTK
CC BY-SA 4.0
2018-10-10T03:47:00.357Z
http://curious.astro.cornell.edu/disclaimer/86-the-universe/black-holes-and-quasars/general-questions/436-what-type-of-energy-does-a-black-hole-have-intermediate
NoWar
CC BY-SA 3.0
2014-10-09T07:20:05.167Z
I think you should at least try to read Wikipedia or something of the like to grasp the basic ideas. You have many errors in your question. Correcting them would take long. You could also go through other questions here in astronomy.stackexchange.com about black holes. Here is the link http://astronomy.stackexchange.com/questions/tagged/black-hole.
harogaston
<black-hole>
Do black holes have energy?
cow9000
# Do black holes have energy?

(Asked by: username_0 on 2014-10-08)

So black holes are created by certain dying stars and when the star runs out of nuclear energy gravity wins out and the star implodes. An entire star’s mass collapses down into a smaller and smaller volume of space. Which then creates a black hole, so my question is, do black holes actually have energy to create that type of vacuum to suck light in?

If a black hole was created by a huge star running out of fuel and then collapsing in on it self, would the black hole have energy and if so where would it come from, or is it just like the vacuum in space with no energy at all?

(Please correct me if I said anything wrong about the black holes as I am very young and don't quiet grasp the concept of it yet.)

**Tags:** black-hole

> **Comments:**
> **username_3**: I think you should at least try to read Wikipedia or something of the like to grasp the basic ideas. You have many errors in your question. Correcting them would take long. You could also go through other questions here in astronomy.stackexchange.com about black holes. Here is the link http://astronomy.stackexchange.com/questions/tagged/black-hole.  
> **username_1**: If I'm reading your question right, you're asking if gravity requires energy.    If the "sucking" requires an energy source and where does gravity's "sucking" energy come from.    I'm pretty sure this has been asked before.  In a nutshell, A massive object with gravity in and of itself has no "sucking" energy.   If you have 2 objects, a heavy body and a smaller body some distance away, the 2 body system has potential energy, And the potential energy can explain the object falling towards a black hole.   That's an oversimplified version of username_7 Liu's post - just thought I'd put it out there.  
> **username_1**: Two related questions on gravity and energy:  https://physics.stackexchange.com/questions/75222/where-does-gravity-get-its-energy-from  and  https://physics.stackexchange.com/questions/7118/is-gravity-energy  
> **username_2**: http://curious.astro.cornell.edu/disclaimer/86-the-universe/black-holes-and-quasars/general-questions/436-what-type-of-energy-does-a-black-hole-have-intermediate  

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## 4 answers

### Answer by username_7 on 2014-10-09. Score: 4 | Accepted answer

An isolated black hole is a vacuum solution of general relativity, so in a very direct sense it does not contain any energy anywhere in spacetime. But perhaps somewhat counter-intuitively, that does not imply that such a black hole has no energy.

Defining the total amount of energy is usually very problematic in general relativity, but in some special cases it is possible. In particular, the usual black hole solutions are all asymptotically flat, i.e., spacetime is just the usual flat Minkowski when far away from the black hole.

Here (or in general when we have a prescribed asymptotic form of the spacetime), we can calculate the total energy-momentum, by essentially measuring the gravitational field of the black hole at infinity. The energy just be one component of energy-momentum.

There are actually two relevant different kinds of 'infinity' here: spatial infinity and null (lightlike) infinity, depending on whether we are 'far away' from the black hole in a spacelike or lightlike direction. There's also timelike infinity, but that just corresponds to waiting an arbitrarily long time, so it's not relevant here. The two different infinities beget different definitions of energy-momentum, giving the the **ADM energy** and the **Bondi energy**, respectively. In a vacuum, the intuitive difference between the two is that Bondi energy excludes gravitational waves.

So the short answer is 'yes', with the caveat that in a more complicated situation, where we can't attribute everything to the black hole itself, the answer to *how much* energy is due to the black hole may be ambiguous or ill-defined.

Note that the ADM and Bondi energy-momenta also define their corresponding measures of **mass**, as the norm of those energy-momenta ($m^2 = E^2-p^2$), but for a black hole we can also define mass more operationally in terms of orbits around the black hole. There are also other alternatives for addressing mass specifically.


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### Answer by username_4 on 2014-10-09. Score: 5

In outer space, a vacuum isn't what sucks in matter to a black hole. That may be the case for your household vacuum cleaner, but everywhere in outer space is essentially a vacuum. Instead, it's the black hole's powerful gravitational pull.

However, black hole can have energy. One type that comes to mind is *angular kinetic energy*. This is the energy that a spinning object has - in this case, a [rotating black hole](https://en.wikipedia.org/wiki/Rotating_black_hole) (see also [Kerr black hole](https://en.wikipedia.org/wiki/Kerr_metric) and [Kerr-Newman black hole](https://en.wikipedia.org/wiki/Kerr%E2%80%93Newman_metric)). Black holes can also have *translational kinetic energy* - the energy of an object in motion. Also black holes have gravitational potential energy - potential energy due to gravity - and [black holes with electric charge](https://en.wikipedia.org/wiki/Reissner%E2%80%93Nordstr%C3%B6m_metric) can have electric potential energy.

So black holes do have energy, although perhaps not in the form you thought.

Keep asking good questions!

I hope this helps.


---

### Answer by username_2 on 2018-10-10. Score: 2

The only way we can detect black holes is through the effect that their gravitating mass has on objects outside the event horizon. These objects can gain energy from the black hole, as they fall into the potential well they heat up and radiate (often in the X-ray region of the spectrum). So black holes have gravitational energy from their mass. A black hole could also have charge, but this is rare in the universe which is largely neutral. Many black holes probably rotate, and these also have rotational energy.

<http://curious.astro.cornell.edu/disclaimer/86-the-universe/black-holes-and-quasars/general-questions/436-what-type-of-energy-does-a-black-hole-have-intermediate>


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### Answer by username_5 on 2016-03-31. Score: 1

The principle of conservation of energy tells us that the amount of energy in the universe is constant. Therefore we can conclude the energy that once made up a star that turned into a black hole cannot be destroyed. So yes according to the principle of conservation of energy a black hole contains energy.

> **Comments:**
> **username_6**: Conservation of energy on a universal scale is not a given and is not required by General relativity.  

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