Does a Black Hole grow in mass?

In summary: It's not simply "an object takes an infinite amount of time", it's "an object takes an infinite amount of time for the black hole to suck it in". Since an event horizon is a boundary, the object can never actually cross it; it's always outside, even as it's being dragged in.
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Nova
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It is confirmed that Black Holes have variations of masses. But these masses are said to be gained from the base mass from the Supernova it's born from. Another way a Black hole gained mass was that the collisions of multiple Black Holes caused it to add on to the mass of each other, such as when two super massive Black Holes collide to form an elliptical galaxy. But if these black holes can gain mass from each other, then it should gain mass from the matter it devours, right?
 
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Depends on where you are looking from and what you count as the mass of the black hole.
In the sense that black holes can "devour matter", yes, they gain mass as a result.
 
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Thread closed temporarily for Moderation...
 
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A thread derailment has been removed and the thread reopened. I remind participants to limit responses to topics about which you have some mainstream scientific knowledge, and to report nonsense and speculation rather than further promulgating it.
 
  • #5
Nova said:
It is confirmed that Black Holes have variations of masses. But these masses are said to be gained from the base mass from the Supernova it's born from. Another way a Black hole gained mass was that the collisions of multiple Black Holes caused it to add on to the mass of each other, such as when two super massive Black Holes collide to form an elliptical galaxy. But if these black holes can gain mass from each other, then it should gain mass from the matter it devours, right?
Right. The usual way to define "mass" here would be the Komar mass before and after matter falls in.
 
  • #6
I think the following discussion is relevant - particularly the last post.
https://www.physicsforums.com/showthread.php?t=355960
... the usual issue about BHs gaining mass is the observation that it takes an object an infinite amount of time, from the POV of a distant observer, to cross the event horizon.
The actual math is trickier than that.
 

1. How does a Black Hole grow in mass?

The growth of a Black Hole's mass is primarily driven by the process of accretion, in which it pulls in and consumes surrounding matter. This matter is heated to extremely high temperatures, emitting radiation that can be observed from Earth.

2. Can a Black Hole stop growing?

Yes, a Black Hole can stop growing if it runs out of matter to accrete. This can occur when the Black Hole is located in a relatively empty part of space, or if it has consumed all nearby matter.

3. Does a Black Hole's mass increase as it consumes matter?

Yes, a Black Hole's mass increases as it consumes matter. This is due to the fact that matter is converted into energy within the event horizon of the Black Hole, adding to its overall mass.

4. Is there a limit to how big a Black Hole can grow?

There is no definitive limit to how big a Black Hole can grow, as it ultimately depends on the amount of matter it is able to accrete. However, there is a theoretical upper limit known as the Eddington limit, which is based on the balance between the gravitational force pulling matter into the Black Hole and the radiation pressure pushing it out.

5. Can a Black Hole lose mass?

Yes, a Black Hole can lose mass through a process called Hawking radiation, in which it emits particles and energy from its event horizon. However, this process is very slow and is only significant for extremely small Black Holes.

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