Welcome, Guest

Author Topic: Making Objects black holes  (Read 4392 times)

rottweiler07

  • ***
  • Posts: 22
Making Objects black holes
« on: August 18, 2009, 05:16:02 PM »
Whenver I bring up the menus for an object and click "black hole," there is a message at the bottom of the screen stating "set the radius so the escape velocity equals the speed of light." I do not know how to do this and it is just confusing me. I anyone could help that would be great!  :)

Naru523

  • Universe Sandbox 1 Beta Team
  • *****
  • Posts: 1295
  • let's walk the true path of life
Re: Making Objects black holes
« Reply #1 on: August 18, 2009, 05:33:34 PM »
Weird...

rottweiler07

  • ***
  • Posts: 22
Re: Making Objects black holes
« Reply #2 on: August 18, 2009, 05:49:22 PM »
Why, weird. Does it work when you click black hole. Also when I click black hole the bject shrinks to like a few centimeters.

Dan Dixon

  • Creator of Universe Sandbox
  • Developer
  • *****
  • Posts: 3243
    • Personal Site
Re: Making Objects black holes
« Reply #3 on: August 18, 2009, 07:08:01 PM »
The message you are getting means that Universe Sandbox is “setting the radius so the escape velocity equals the speed of light." Which is a simplistic definition of what defines a black hole. A blackhole in Universe Sandbox is a body who’s radius is such that its escape velocity is equal to the speed of light. (the escape velocity is how fast something needs to travel to escape the gravitational tug of the body)

The radius a body needs to be so the escape velocity equals the speed of light is called the Schwarzschild radius:
http://en.wikipedia.org/wiki/Schwarzschild_radius

The “black hole” button that you’re hitting only changes the body’s size. If you do it on the Earth it makes it about 3 cm across. In reality if you made the Earth this size it would be considered a black hole, but there’s so little mass it would explode apart from the pressure.

You probably will have better success making the body’s mass much greater (and turn down the time step). This will cause it to suck in everything around it.

I’m sorry this isn’t more clear. I expect this to be much more clear in the next release.

rottweiler07

  • ***
  • Posts: 22
Re: Making Objects black holes
« Reply #4 on: August 18, 2009, 07:52:09 PM »
Ok thanks. I will try that.  :)