How can a star turn into a black hole, with the law of conservation of mass?

Click For Summary

Discussion Overview

The discussion centers on the transformation of a star into a black hole, specifically addressing the implications of the law of conservation of mass and energy during this process. Participants explore various mechanisms of black hole formation and the fate of mass during and after the collapse.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants question where all the mass goes during the formation of a black hole.
  • One participant states that black holes have a mass that is the same or less than the mass of the original star, noting that a nova event can scatter most of the mass into space.
  • Another participant explains that from a distance, a black hole behaves similarly to a star or planet, with gravitational effects becoming significant only when one is very close to it.
  • A participant introduces the idea that while conservation of mass is not commonly referenced, mass can be considered equivalent to energy, suggesting that mass loss during black hole formation is compensated by energy in other forms, such as electromagnetic radiation and gravitational radiation.
  • One participant proposes a conceptual equivalence between the laws of conservation of mass and energy, suggesting that they can be viewed as interchangeable in this context.

Areas of Agreement / Disagreement

Participants express differing views on the conservation of mass versus energy, with some suggesting they are interchangeable while others emphasize the distinction. The discussion remains unresolved regarding the specifics of mass loss and conservation during black hole formation.

Contextual Notes

Participants reference various mechanisms for black hole formation, including direct collapse, remnants from supernovae, and mergers, but do not reach a consensus on the implications for mass conservation. The discussion highlights the complexity of defining mass and energy in the context of astrophysical processes.

ilikefun411
Messages
1
Reaction score
0
where does all the mass go?
 
Astronomy news on Phys.org
Black holes have a mass that is the same or less then the mass of the star that collapsed into the black hole. If there is a nova event connected to the collapase, most of the mass will be scattered into space, if the remaining mass is large enough then it will collapase into a black hole.
 
It should be noted that black stars don't have an immense gravitational field. From far away, a black hole acts just like a star, or a planet. It's only when you get really close to a black hole that the gravity starts acting strange... because gravity is proportional to the distance from the center of an object squared, if you're, say, standing on the surface of the earth, you're 4,000 miles from the center of the earth. A black hole with the mass of earth, however, may have a radius of 4 miles. So if you're 10,000,000 miles away from earth, it has the same gravitational pull as if you're 10,000,000 miles away from the black hole. But if you're 1 mile above the surface of the earth, you're 4001 miles away from the center. If you're 1 mile above the surface of the black hole with the same mass, you're 5 miles from the center
 
ilikefun411 said:
where does all the mass go?
I haven't heard of "conservation of mass", only conservation of energy. But, since mass = energy (e=mc2) I guess it could be called either.(?)

A BH can form from several methods; direct collapse of a massive star, large core remaining from a Type II supernova, merger of two massive bodies etc. Any BH formation mechanism causes some mass loss and since mass = energy, some "mass loss" is carried away as EM radiation, gravitational radiation and sometimes conversion of angular momentum.

So, mass/energy will actually remain at the same total, just not all as "particles of matter".
 
for conservation of mass, replace energy with mass in the law of conservation of energy. it's the same thing, like you said.
 

Similar threads

Undergrad Can there be slowly-falling accretion disks in black holes?
  • · Replies 11 ·
Replies
11
Views
2K
Stargazing Merger of two black holes (video)
  • · Replies 7 ·
Replies
7
Views
4K
Undergrad What affects light near black holes and stars?
  • · Replies 2 ·
Replies
2
Views
2K
High School What keeps most galactic stars from falling into the centeral black hole?
  • · Replies 6 ·
Replies
6
Views
3K
Undergrad Does light bend around black holes?
  • · Replies 49 ·
2
Replies
49
Views
7K
High School So, a black hole and an antimatter star bump into each other....
  • · Replies 5 ·
Replies
5
Views
3K
Undergrad M31-2014-DS1, slow disappearance of a massive star
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad Why Does Gravity Remain when Star Mass Dissipates?
  • · Replies 10 ·
Replies
10
Views
2K
Stargazing Dark matter and its effect on the orbit of stars
  • · Replies 13 ·
Replies
13
Views
3K
High School Is it possible for a giant star to have a black hole inside it?
  • · Replies 11 ·
Replies
11
Views
3K