You read correctly. Though the mass is finite, it's compacted into an infinitely small space. So, if you just look at the density forumla (D = M / V) and divide by the volume (zero) you end up with infinity no matter how much mass you have (as long as the mass isn't zero also).

That's assuming that the mass of a black hole is compacted into an infinitely small space, however. But because we can't see past the event horizon, we can't know for sure. It's likely, though, since there's nothing stopping it from collapsing to zero size- the gravitational force exceeds all the other forces present.

Black holes are weird things...

-Joe Antognini

• So how can we calculate the mass of the BH? - bazukaz - January 25, 2005 - 14:00 UTC
  • Gravity is the weakest force of all - secretary - January 25, 2005 - 18:53 UTC
    • Singularity - bazukaz - January 25, 2005 - 23:19 UTC
      • Only in theory - secretary - January 26, 2005 - 02:15 UTC
        • Only in theory - bazukaz - January 26, 2005 - 09:43 UTC
          • Event Horizons Cut Us Off - splat - January 30, 2005 - 06:17 UTC