Can black holes truly be infinite?

In summary, the mass of a black hole is finite, generally equal to the mass of the star that collapsed to form it. While it can increase in mass over time, its gravitational attraction remains the same as the star that created it. The main difference is that the star's mass has a physical extent, while a black hole's gravity gets stronger the closer one gets to its center, with an event horizon at a certain radius. Outside of this region, the gravity is the same for both a star and a black hole.
  • #1
Dan4
5
2
Good morning. Not sure if I am doing this right, but I just wanted to ask a question.
 
Astronomy news on Phys.org
  • #2
Also, I'm not looking for homework help. Just an understanding.
 
  • #3
I am assuming that a black hole has an infinite mass in any direction, from a direct line from any observer.
 
  • #4
Dan4 said:
I am assuming that a black hole has an infinite mass in any direction, from a direct line from any observer.

A black hole has a finite mass. This is generally the mass of the star that collapsed to form it.
 
  • #5
So the mass doesn't increase over time, and if it's the same mass of the star that created it, how does it have an event horizon or the same gravitational "footprint" as the star that created it?
 
  • #6
Dan4 said:
So the mass doesn't increase over time, and if it's the same mass of the star that created it, how does it have an event horizon or the same gravitational "footprint" as the star that created it?

It can of course increase in mass over time by objects crashing into it. But, that can happen to a star as well. In any case, the mass remains finite.

The gravitational attraction of a black hole is the same as the star that created it. Except that the star's mass has a physical extent: the Sun is about 1.5 million km across. So, you can only get so close to the centre of the Sun before you crash into the surface. But, if the Sun were a black hole you could get closer than that and the gravity would get stronger the closer you got. And at a certain radius - it would be about 3km for the Sun - you would reach the event horizon.

In other words, the gravitational difference between a star and a black hole is in the region closer than the surface of the star. Outside of that, the gravity is the same for both.
 
  • #7
Hey thanks! I was focused on the wrong thing and didn't take the radius into account.
 
  • Like
Likes berkeman and PeroK

1. Can black holes truly be infinite?

Yes, according to current scientific theories, black holes can be infinitely large. This is because the gravitational pull of a black hole is so strong that it can continue to pull in matter and energy indefinitely, making its size theoretically infinite.

2. How do we know that black holes can be infinite?

Scientists have observed the effects of black holes on their surrounding environment, such as the distortion of light and the acceleration of nearby objects. These observations, along with mathematical calculations, support the idea that black holes can be infinitely large.

3. What is the event horizon of a black hole?

The event horizon is the point of no return for anything that enters a black hole. It is the boundary where the gravitational pull of the black hole becomes so strong that not even light can escape. Beyond the event horizon, the black hole's gravity is infinite.

4. Can black holes ever stop growing?

It is possible for a black hole to stop growing if it runs out of material to consume. However, this is unlikely as black holes are constantly pulling in matter and energy from their surroundings. It is also possible for black holes to merge with other black holes, resulting in a larger black hole.

5. Are there any limits to the size of a black hole?

According to current scientific theories, there is no known limit to the size of a black hole. However, it is possible that the laws of physics may break down at the center of a black hole, known as the singularity, making it impossible to accurately determine its size.

Similar threads

  • Astronomy and Astrophysics
Replies
9
Views
1K
  • Astronomy and Astrophysics
Replies
11
Views
2K
  • Astronomy and Astrophysics
Replies
10
Views
1K
  • Astronomy and Astrophysics
Replies
5
Views
1K
  • Astronomy and Astrophysics
Replies
11
Views
1K
  • Astronomy and Astrophysics
Replies
4
Views
2K
  • Astronomy and Astrophysics
Replies
27
Views
3K
  • Astronomy and Astrophysics
Replies
4
Views
1K
  • Astronomy and Astrophysics
Replies
2
Views
1K
  • Astronomy and Astrophysics
Replies
5
Views
1K
Back
Top