Suppose you are old and as a last act want to see for yourself what it is to cross an event horizon (knowing you cannot come back). To get there, though, you have to survive the tidal forces. Given this, should you jump into a 10M stellar-mass black hole such as the one in Cygnus X-1, or are you better off at the 3×10 6 M black hole in the centre of our Galaxy? (To estimate this, calculate the tidal acceleration at the event horizon – and compare your results again to Earth’s gravity; use the Newtonian estimate, even though this obviously will not be entirely correct.)