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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."
Because "Gravastars" are still very much a new and thus fringe theory.
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Not only is it a cool picture, but this is a pretty interesting thing to witness. In my initial reaction I thought "How can we see this in our lifetimes?" It seems that, as mentioned in the article, "[t]his collapse is extremely fast, and the core collapses into a neutron star in about one second."
The collapse into a black hole in such a short time (also in the article) is somewhat expected, because the gravity will be so strong. This should be a pretty neat and real way to verify if our view on black hole formation and the associated astro-physics that accompany it are mostly correct.
There are only 10 kinds of people in this world... those who understand binary and those who don't
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.)
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?
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You're promising not to reply to my posts, now please STOP DOING IT.
Fine. _I'll_ reply.
Gravastars are an interesting idea, but they:
a) Propose modifications to physics (the phase transition that gives rise to a different type of space in the interior).
and
b) Attempt to solve a problem that doesn't necessarily exist (embodiment of entropy in black holes, which string theory takes a fairly good stab at explaining).
Thus, I'm skeptical of claims that gravastars exist, barring observations supporting their existance or wider acceptance by the scientific community.
At least in the paper I've managed to dig up so far, they acknowledge many othe potential models of how black holes work, and suggest types of observations that would help determine whether their model is accurate (i.e., they don't claim it's the One True Model off the bat). This is one of the hallmarks of good science.
Observations to look for are gravity-wave signatures of resonance modes in the stiff shell surrounding the gravastar, and optical signatures of impacting matter interacting with this shell. The first should be possible when we get sufficiently sensitive gravity wave detectors online, and the second should be possible from observations of accretion disks in known black hole/other star binary pairs once Mazur and Mottola have worked through the math to figure out what the observational signatures should _be_. Thirdly, if you could get close enough to take good measurements, you'd be able to distinguish between gravastar-type black holes and Hawking-Bekenstein black holes by different radiation signatures coming off of them, but that requires being right next to the hole and having instruments sensitive enough to detect very faint, low-frequency thermal radiation.
In summary, claiming that the gravastar model _is_ what black holes are is very, very premature.
They probably have more data than that, for instance our sun has no chance of even supernovaing, much more massive stars are required to do that.
2*31*37*263
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?