3 ms·
Signals take an infinte amount of time to reach a distant observer from just outside the event horizon. Which means we cannot see the event horizon or what is b
by Santosh83 9y ago
Signals take an infinte amount of time to reach a distant observer from just outside the event horizon. Which means we cannot see the event horizon or what is beyond, and we cannot also 'see' the event horizon being formed, or any matter crossing the event horizon. When the star collapses, light takes progressively longer to reach an outside observer, and eventually becomes too dim to detect. The same thing happens with an object falling into a black hole. But since the gravitational effect can still be felt, we cannot also say that the black hole never formed. At all events, a region of spacetime that emits no discernable signals has formed. You can call it a black hole or speculate further about what it is, but the phenomenon is still right there.
- wallace_f 9y ago>we cannot also 'see' the event horizon being formed I think what you're saying here is the confusing part. If no observer in the universe can ever witness a black hole being formed, it stands to reason they cannot exist (within the reference frame of observers outside it). Now I'm not asserting this as true or not, because I wouldn't assert such contrarian conclusions on a subject I have not properly studied; rather I am just highlighting what appears to be the confusing bit here.
- Santosh83 9y agoWhat is meant when we say we expect to see a black hole, or event horizon, forming? If we mean that we can no longer detect any signal from particular region, then to that extent, we can assert that what we call as a black hole exists there. We're defining it by its negatives, but I can't see how one can say that even those negatives don't exist. Also its gravitational effects can be detected, so that is another reason why merely claiming a black hole doesn't exist, or never forms, seems to rather miss the mark.