Hijack from What if the Sun turned into a Black Hole?

[Olin]

On 11/8/2018 at 12:49 PM, geordief said:

No I know it can't  normally but what if it did and we could  decide on the radius of the new body?

 

If the radius was small enough would it cease to have much effect on the  movement of the planets (would they lie outside its region of gravitational influence? )

 

Is there a limit to how small a radius the "new body" could have? Does its radius depend  directly on the mass of the bodies that have  been incorporated into it  in the first place? Does its radius remain the same provided there are no more additions of massive bodies?

 

Who do you imagine has the answers to these questions, and where do you imagine that they got these answers

[Strange]

1 minute ago, Olin said:

Who do you imagine has the answers to these questions, and where do you imagine that they got these answers

(a) Physicists.

(b) Physics.

[Olin]

2 hours ago, Strange said:

(a) Physicists.

(b) Physics.

Can you name the physicist who has this information?  Then tell us where he got it? And what methods were used to prove the hypothesis?

[beecee]

11 minutes ago, Olin said:

Can you name the physicist who has this information?  Then tell us where he got it? And what methods were used to prove the hypothesis?

Most all physicists have this information on BH's and what it entails for their formation...If I had to list some who originally worked out the intricate details and maths, we have Schwarzchild...Chandreskar, Bethe, Kerr, Hawking, Penrose, Thorne, for starters. In actual fact BH's of sorts, were first theorised to exist in the late 1700's under Newtonian mechanics by a guy called Mitchell. These though were actually what is termed as Dark Stars.

BH's are now confirmed with the discovery of gravitational waves, and of course the evidence that has been available for at least 50 years, the observational action of matter etc, that can only be put down to some entity that has exceeded its Schwarzchild radius...aka a BH.

Edited November 13, 2018 by beecee

[Olin]

1 minute ago, beecee said:

Most all physicists have this information on BH's and what it entails for their formation...If I had to list some who originally worked out the intricate details and maths, we have Schwarzchild...Chandreskar, Bethe, Kerr, Hawking, Penrose, Thorne, for starters. In actual fact BH's of sorts, were first theorised to exist in the late 1700's under Newtonian mechanics by a guy called Mitchell. These though were actually what is termed as Dark Stars.

Where did most physicist get this information, and how was the information verified.  Hawking admitted that he was wrong, but I wonder how would anyone actually know if he was wrong or right?

https://www.rferl.org/a/1053983.html

The world's theoretical physicists long have accepted that the amount of matter and energy in the universe remains constant. They also have been confounded by the discoveries of famed cosmologist Stephen Hawking that suggest that matter and energy can disappear forever into black holes of super gravity created when stars burn out. Now Hawking says he may have solved the paradox by proving that he has been wrong all these years.

 

[Strange]

31 minutes ago, Olin said:

Can you name the physicist who has this information? 

All of them.

32 minutes ago, Olin said:

Then tell us where he got it?

University and practical research.

32 minutes ago, Olin said:

And what methods were used to prove the hypothesis?

Science. You know: use the model to make predictions, test those against observation and experiment.

Do you need a list of experiments specifically to test our theories of gravity? There is well over 300 hundred years of experiments testing our understanding of gravity. And over 100 years of testing the details of general relativity specifically.

Can you say why we might doubt this?

18 minutes ago, Olin said:

Where did most physicist get this information, and how was the information verified.  Hawking admitted that he was wrong, but I wonder how would anyone actually know if he was wrong or right?

https://www.rferl.org/a/1053983.html

The world's theoretical physicists long have accepted that the amount of matter and energy in the universe remains constant. They also have been confounded by the discoveries of famed cosmologist Stephen Hawking that suggest that matter and energy can disappear forever into black holes of super gravity created when stars burn out. Now Hawking says he may have solved the paradox by proving that he has been wrong all these years.

 

That paragraph is so confused. Hawking never said energy can disappear. You need to find a better source of information. Even Wikipedia (for all its flaws) is a better resource than some random blog, or whatever that was.

[Olin]

1 minute ago, Strange said:

All of them.

University and practical research.

Science. You know: use the model to make predictions, test those against observation and experiment.

Do you need a list of experiments specifically to test our theories of gravity? There is well over 300 hundred years of experiments testing our understanding of gravity. And over 100 years of testing the details of general relativity specifically.

Can you say why we might doubt this?

Doubt? nothing can ever escape from a black hole, everything that goes in is lost forever.

So are you claiming that the law of conservation of mass is wrong, because if it is science means nothing and we need to start all over again.

Again, nothing has ever disappeared in history, it only changes form

[Strange]

7 minutes ago, Olin said:

So are you claiming that the law of conservation of mass is wrong

Why would you think that? And how is it relevant?

Maybe you should learn about black holes before making silly assertions. If a 1 kg mass falls into a black hole, then the black hole increases in mass by 1kg.

So, again, why would we doubt the laws of gravitation that we have known and tested for 300 years?

[beecee]

52 minutes ago, Olin said:

Where did most physicist get this information, and how was the information verified.  Hawking admitted that he was wrong, but I wonder how would anyone actually know if he was wrong or right?

Through the application of knowledge, mathematics and observation. I'm not a mathematician so no I'm unable to produce the maths, but more to the point, would you even understand the maths?

Quote

 

https://www.rferl.org/a/1053983.html

The world's theoretical physicists long have accepted that the amount of matter and energy in the universe remains constant. They also have been confounded by the discoveries of famed cosmologist Stephen Hawking that suggest that matter and energy can disappear forever into black holes of super gravity created when stars burn out. Now Hawking says he may have solved the paradox by proving that he has been wrong all these years.

 

Hawking's paradox and whether he was wrong or otherwise, has to do with what is known as the information paradox and firewall concept with regards to the EH,  not on the existence of BH's themselves. The existence of BH's is now beyond any reasonable doubt, and so far 5 BH collision scenarios have been determined by LIGO and VIRGO 

[Strange]

6 minutes ago, beecee said:

Hawking's paradox and whether he was wrong or otherwise, has to do with what is known as the information paradox and firewall concept with regards to the EH,  not on the existence of BH's themselves. The existence of BH's is now beyond any reasonable doubt, and so far 5 BH collision scenarios have been determined by LIGO and VIRGO 

And, actually, the existence of black holes, is irrelevant to the original question. One could just as well ask "what if the Sun's mass were compressed to a 6 km diameter sphere" or "what if the sun's mass were concentrated at a single point". The answers would have been exactly the same and anyone since Newton could have answered them.

(But there is almost no doubt about the existence of black holes.)