Birth of Black Hole Possibly Being Observed

TheTXLibra writes "Robert Roy Britt reports on Space.com that we may now be witnessing the earliest stages of black hole development. Star SN 1986J, began to collapse in 1983 into a neutron star, resulting in a supernova explosion in 1986. If the mass of the neutron star reaches 1.4 times the mass of Earth's Sun, it will theoretically collapse into a black hole, if not, it will stabilize as a neutron star."

Comments

Knowing where to look...

[beeplet]

The article didn't even mention one of the most important reasons this is interesting - so far the only stellar-mass blackhole candidates are in binary systems (where you can infer the mass of an unseen object from the orbit of the visible star). Otherwise, you can't see find a black hole unless you know where to look - and now we do.

(I guess you could also theoretically look for black holes by their gravitational lensing effects, but you would have to monitor a huge number of stars and hope that a black hole intercepts your line-of-sight to one of them, so not very practical.)

The Nature of Probability

[NSash]

Yes, it does. Probability is a construct that depends on available information.

For example, let's say someone flips a coin and you call the result in mid-air. In reality, the result of the coin toss is already determined at this point. However, as far as you're concerned the probability of either result is 50%. Or even better, let's say that you're trying to guess which of two cups holds a ball. The person who placed the ball knows with complete certainty which cup holds it, but as far as you're concerned the probability is 50% that the ball is in either cup.

Probability doesn't exist independently of observation. Probability is simply a measure of expectation.

Re:The Nature of Probability

[logpoacher]

Ok, what you say is right, but I didn't think that that's what the original poster was complaining about.

I think he was trying to say that for "roughly equal" to apply, we must presume to know that P(black hole) ~= P(neutron star). Maybe we do know that, perhaps because that's generally the case (due to distribution of stars of different masses), or because we know something special about this particular case.

But if not, then the quote in the article is falling into the "either it'll happen or it won't" fallacy. Casino owners love this style of thinking, because it induces people to forget that the odds are against them, and to bet anyway: "either I'll win or I won't". It's common to confuse "2 outcomes" with "50% chance", and the article sounds like it has done so, but then again it's possible that it hasn't.

Unfortunately, in both your examples, each outcome is exactly as likely as the other - they're symmetrical (as long as they're fair!), so they don't illustrate the fallacy, because you were drawing attention to something else. Try this - it's similar to your examples, but it's asymmetric: Consider a (normal 6-sided) dice roll, where you're asked to guess if the result is a 4. The dice has rolled, but you haven't seen the result yet, and the chances of getting your 4 are 1/6, and 5/6 of not getting it - they're not "roughly equal". Does that work for you?

How long until they know?

[egon]

I glanced through the article and was absolutely amazed (not knowing that much about this subject) that the collapse into a neutron star took a mere second. Considering the scale of the event, that's just astounding to me.

What I didn't see was any indication when they'll be able to determine whether the star is going to remain a stable neutron star or become a black hole. Does anybody with actual knowledge in the subject care to comment?