I have recently read some hard science-fiction story based on an assumption that if time stops (from external observer's perspective) on the event horizon of black hole, then in an anti-matter black hole's horizon the time would pass infinitely fast (same perspective)

I thought it was impossible, but I'm not sure anymore.

What would be the effect of approaching the event horizon of an anti-matter black hole?

Is it possible that an infinity of time passes in a finite time (from our point of view) ?

Fun follow-up: if so, can a result of infinite computation be returned to our timeline?


1 Answer 1


A black hole may result from a gravitational collapse of either matter or antimatter, but the black hole itself is a geometrical object — a feature of the shape of space-time, not a material object. The behaviour of space-time at or near to a black hole is the same however it originates, so long as the bulk is electrically neutral; and a charged black behaves the same regardless of whether its charge is due to having absorbed e.g. more protons or more positrons.

Therefore, there is no real distinction between a "matter" black hole and an "antimatter" black hole; in particular, a black hole which happened to form due to the gravitational collapse of a large amount of antimatter would be indistinguishable from a black hole arising from a collapse of matter (or indeed from a sufficiently dense combination of matter and antimatter, arising from a dense nugget of matter and a dense nugget of antimatter brought together that only achieve the "critical density" as they approach each other).

  • $\begingroup$ "The behaviour of space-time at or near to a black hole is the same however it originates." This is false. For example, a black hole with electrical charge differs from an electrically neutral black hole. $\endgroup$
    – user4552
    Commented Oct 13, 2012 at 1:22
  • $\begingroup$ Thanks for clearing this for me Niel. @BenCrowell Could You elaborate (or better - give a link)? $\endgroup$
    – naugtur
    Commented Oct 13, 2012 at 8:33
  • $\begingroup$ @BenCrowell: right, a bit too hastily written. Edited. $\endgroup$ Commented Oct 13, 2012 at 9:39
  • $\begingroup$ @naugtur: en.wikipedia.org/wiki/No-hair_theorem $\endgroup$
    – user4552
    Commented Oct 14, 2012 at 18:54

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