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Scientists May Get Best View Yet of a Black Hole in Action

80 点作者 arijitraja大约 11 年前

7 条评论

pdonis大约 11 年前
One small nitpick about a statement in the article; it says:<p><i>Though we think of them as cosmic vacuum cleaners, black holes are actually just like any other massive body, such as a star. This means other objects can safely orbit them, until they get within a particular distance and pass what’s known as the event horizon, after which there is no escaping being sucked in.</i><p>Technically, you can&#x27;t &quot;safely orbit&quot; a black hole if you&#x27;re any closer to it than three times the horizon radius. That is, there are no stable free-falling orbits, like orbits around a planet or star, closer than that. If you want to get closer than that to the event horizon without falling in, you will need to continuously fire your rockets to hold yourself at altitude against the hole&#x27;s gravity.
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sillysaurus3大约 11 年前
A question for the physicists on HN: I&#x27;ve heard that black holes emit radiation. But if nothing can go faster than the speed of light, and a black hole&#x27;s gravity is so strong that not even light can escape, then how can a black hole emit anything?<p>Is there a kind of black hole which is so massive that not even that radiation can escape, or do all black holes emit some kind of radiation? (In fact, do they emit radiation proportional to their size?)
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fargolime大约 11 年前
If only black holes weren&#x27;t illogical! [1] Any decent software developer (i.e. highly logical thinker) who knows basic info about black holes can look at the picture there to quickly see that black holes are inconsistent with the core postulate of general relativity, the equivalence principle. They&#x27;re a bug! (which Einstein spent a decade trying to find, or some other way that nature could prevent black holes he thought didn&#x27;t &quot;smell right&quot;, and no that&#x27;s not my blog) [2] is previous discussion showing no bona fide flaw in the argument. I&#x27;ve not seen anyone refute that simple picture, which should be easy if it&#x27;s incorrect.<p>That black holes are a bug doesn&#x27;t mean we can&#x27;t explain observations. Gravitational redshift still exists to explain massive objects emitting no discernible light (might be only one photon every year, away from Earth).<p>[1] <a href="http://finbot.wordpress.com/2008/03/05/no-black-holes/" rel="nofollow">http:&#x2F;&#x2F;finbot.wordpress.com&#x2F;2008&#x2F;03&#x2F;05&#x2F;no-black-holes&#x2F;</a><p>[2] <a href="https://news.ycombinator.com/item?id=4926603" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=4926603</a>
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andrewflnr大约 11 年前
<p><pre><code> Astronomers know that as recently as a few hundred years ago, the Milky Way’s central supermassive black hole was producing much more radiation. </code></pre> Wow, what a near miss. Would that have been visible at all? To think that if human technology had kicked off a couple centuries earlier we might have observed a black hole eating something already, that the answers to our questions about black holes could be common knowledge... wow.
shire大约 11 年前
this might sound like a stupid question but what happens when you get sucked up by a black hole? what&#x27;s in the other side of it.
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th3iedkid大约 11 年前
well yesterday some were talking about tracking a plane lost in earth and today i read about tracking a gas cloud in space!And supposedly the latter seems more like a soccer penalty shot!
maxjones1大约 11 年前
mumble, mumble, something....Oprah...