It is currently Sat Sep 21, 2019 8:01 pm


Post new topic Reply to topic  [ 11 posts ] 
Author Message
 Post subject: Finally a Black Hole
PostPosted: Thu Apr 11, 2019 8:20 pm 
Offline

Joined: Thu Nov 10, 2005 10:48 am
Posts: 27
Location: Derby
Amazing news of the first direct image of a Black Hole in galaxy M87. Strangely I was part way through re-reading the novel BLACK HOLES by the S.F. writer Jerry Pournelle for the first time since 1978, it's been in my bookcase since then.
In it he states " Black Holes remain a theory. No-one has ever seen one - indeed, by definition no one will EVER see one"
Motto:- Never guess the future, apart from the astronomical future becoming utterly amazing.
The book is probably only available in an OXFAM shop now but a good, if now dated, read.

_________________
Steve P


Top
 Profile Send private message  
 
 Post subject: Re: Finally a Black Hole
PostPosted: Mon Apr 22, 2019 2:43 pm 
Offline

Joined: Thu Jun 07, 2018 11:50 am
Posts: 23
Hi! You can still get the Pournelle Black Holes book on Amazon UK... just bagged a 1st ed. paperback for £5.95 inc. shipping... many cheaper options too :D

_________________
"Where the telescope ends, the microscope begins. Which of the two has the grander view?" Victor Hugo


Top
 Profile Send private message  
 
 Post subject: Re: Finally a Black Hole
PostPosted: Tue Apr 23, 2019 1:35 pm 
Offline

Joined: Thu Nov 10, 2005 10:48 am
Posts: 27
Location: Derby
Yes, no surprise it is available on Amazon online.... I must really try and join the 21st century!

_________________
Steve P


Top
 Profile Send private message  
 
 Post subject: Re: Finally a Black Hole
PostPosted: Tue Apr 23, 2019 8:12 pm 
Offline

Joined: Thu Jun 07, 2018 11:50 am
Posts: 23
:D :D :D

_________________
"Where the telescope ends, the microscope begins. Which of the two has the grander view?" Victor Hugo


Top
 Profile Send private message  
 
 Post subject: Re: Finally a Black Hole
PostPosted: Wed Apr 24, 2019 10:39 am 
Offline

Joined: Mon Jan 09, 2006 11:05 am
Posts: 5264
Location: Lancashire
There's an interesting article on black holes in the current issue of NEW SCIENTIST. A black hole is definitely an object not to be messed with. Astronauts, enter at your own risk :shock: :lol: .

_________________
brian


Top
 Profile Send private message  
 
 Post subject: Re: Finally a Black Hole
PostPosted: Thu Apr 25, 2019 8:47 pm 
Offline

Joined: Sat Dec 11, 2004 8:18 pm
Posts: 6500
Location: Manchester
Steve, Sue & BrianL
Sorry to be just another grumpy old codger but : -
Do we really need to know more - we can't even avoid problems with small drones. So is it really desirable to try to get friendly with Black Holes.
Best wishes from Cliff


Top
 Profile Send private message  
 
 Post subject: Re: Finally a Black Hole
PostPosted: Fri Apr 26, 2019 1:09 pm 
Offline

Joined: Mon Jan 09, 2006 11:05 am
Posts: 5264
Location: Lancashire
It depends Cliff on whether we are feeling suicidal. :wink:

_________________
brian


Top
 Profile Send private message  
 
 Post subject: Re: Finally a Black Hole
PostPosted: Sat Apr 27, 2019 8:18 am 
Offline

Joined: Fri Dec 10, 2004 10:34 pm
Posts: 356
Location: Surrey
You have to be careful when you say this is an image. The U-V plane coverage is sparse as can be seen from the on-line papers about the observation. As a result information is only available about part or the image. It is a bit like being given 10 to 20% of the pieces of a jigsaw and being told where they fit but not being given the picture on the box !

The image is the result of a computer model based on the physics of the black hole event horizon that is a best fit to the 10 to 20% of the pieces.

_________________
Engineer @ Work - Astronomer @ Play


Top
 Profile Send private message  
 
 Post subject: Re: Finally a Black Hole
PostPosted: Sat Apr 27, 2019 3:07 pm 
Offline

Joined: Mon Jan 09, 2006 11:05 am
Posts: 5264
Location: Lancashire
The partial image is compelling John. As we know, some theorists have said that a black hole could be a portal to somewhere else.
It might be that if we fell into one, we'd pop up in a Calcutta restaurant, where we could sample real Indian food, then saunter over to the original black hole. :wink: .

_________________
brian


Last edited by brian livesey on Thu May 02, 2019 2:56 pm, edited 1 time in total.

Top
 Profile Send private message  
 
 Post subject: Re: Finally a Black Hole
PostPosted: Sat Apr 27, 2019 4:18 pm 
Offline

Joined: Mon Jan 18, 2010 9:25 am
Posts: 5296
I did not want to spoil the party, but I also have doubts about the veracity of the image.

Regards,
David


Top
 Profile Send private message  
 
 Post subject: Re: Finally a Black Hole
PostPosted: Sat Apr 27, 2019 5:52 pm 
Offline

Joined: Fri Dec 10, 2004 10:34 pm
Posts: 356
Location: Surrey
Brian,

From what I understand of the theory the black hole needs to spin and you need to enter with sufficient velocity to miss the singularity. If you manage that I beleive you will end up in another universe which would have a spinning black hole. If you repeat the process you end up in another universe, this happens each time you never visit any of the universes you have been to before ! Welcome to one branch of the multiverse theory.

David,

There is some relevant information in the book 'The Science of Interstellar' by Kip Thorne. He wrote most of the equations for what a spinning black hole should look like for the movie. One thing is that the space is bent to such an extent that you can see the light from accretion on the rear of the black hole event horizon that would normally be hidden. This also contains the useful equation of how long it takes to orbit the event horizon at the speed of light for different mass black holes. This time is relativly short for the Super massive BH in M87 but much shorter for Sagittarius A* , the time gets shorter the smaller mass the black hole has.

_________________
Engineer @ Work - Astronomer @ Play


Top
 Profile Send private message  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 11 posts ] 

All times are UTC


Who is online

Users browsing this forum: No registered users and 10 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB® Forum Software © phpBB Group