Hello,

I am also trying to use the time dilation tool for a supermassive black hole, specifically, TON 618, which has approximately 66 Billion solar masses. However. I continue to get imaginary numbers. Here is the rundown:

So this gives us a horizon radius of 1.949x10^14 m, or 1.949x10^11 km

Converting to g, this gives us 23.515 g (doesn't this seem really low?)

Entering these figures, I keep getting imaginary numbers. Does I make a mistake somewhere along the line? Thanks in advance.

Dear David,

Thank you for your reply. Unfortunately, I need further clarification here too. What does 0.00707089 correspond to? Is that how many seconds of my time near the black hole passes relative to my friend's at a safe distance?

I looked into your book on Amazon ($175!). Remember -- I'm a graphic artist and haven't done algebra in twenty years. I can tell you the difference between Helvetica and Helvetica Neue, or make you a darn good logo ;-)

Hi Jack, the answer to you question is 63.6 years. You can get easily this value using Wolfram|Alpha:

1. Ask Wolfram|Alpha for "black hole 10 solar masses"

   

2. Then go to the Wolfram|Alpha gravitational time calculator and insert the previous values for the horizon radius, the surface gravity and 90 years (time that your friend turns 100) and you will get the answer:

   

A good starting point is On Continued Gravitational Contraction by J. R. Oppenheimer and H. Snyder. If I remember it correctly that is the nice paper where light cones fall graceful along the geodetic lines of the metric of the black hole into it, explaining the event horizon virtually by means of illustration ... a point that could be appealing to a graphic artist.