View Poll Results: When blackholes collide,what happens to the singularity?
Does gravity force them together? 5 33.33%
Is there a cataclysmic explosion,and they are destroyed/ 2 13.33%
Do both add there gravity,don't merge,and become a bigger one? 8 53.33%
Voters: 15. You may not vote on this poll

Register to reply

When blackholes merge.

by chosenone
Tags: blackholes, merge
Share this thread:
Alexander
#19
May2-03, 08:06 PM
P: n/a
Note that if two ordinary masses with radius r1 and r2 collide (say, two planets, or water droplets merge) then radius of resulting mass is NOT r1+r2, but rather (r1^3+r2^3)^1/3.
marcus
#20
May2-03, 08:19 PM
Astronomy
Sci Advisor
PF Gold
marcus's Avatar
P: 23,119
Originally posted by Alexander
Note that if two ordinary masses with radius r1 and r2 collide (say, two planets, or water droplets merge) then radius of resulting mass is NOT r1+r2, but rather (r1^3+r2^3)^1/3.
Thanks! that is a good way to see a way that the black holes differ from droplets!
In Wheeler's case of the two black holes (which get rid of mass-energy by gravity waves as they coallesce)
the new mass is
sqrt (m^2 + M^2)
and so the new radius is
sqrt (r^2 + R^2).

But with the two droplets the new mass is
for all practical purposes
m+M
and as you point out the new radius is
cuberoot(r^3 + R^3)


Register to reply

Related Discussions
Merge sorting Programming & Computer Science 2
What happens when you fall into a blackhole? Beyond the Standard Model 0
SR forbides BHs and GR demands them Special & General Relativity 1
Would a black hole be able to suck-in another blackhole? Astronomy & Astrophysics 9
What happens when two black holes meet? Astronomy & Astrophysics 4