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Space Science

Slowly Pulling Facts from Black Holes 261

Posted by ScuttleMonkey from the cosmic-vacuum-cleaner dept.
lee1 writes "Astronomers have proven the existence of the event horizon, the 'point of no return' that surrounds black holes. An MIT and Harvard team said they showed its existence by looking for X-ray bursts from neutron stars and more compact objects thought to be black holes." Relatedly beuges writes "IOL is reporting that by tracking the death spiral of cosmic gas at the center of a galaxy called NGC1097, scientists figured that material moving at 177 000km an hour would still take eons to cross into a black hole. 'It would take 200 000 years for gas to travel the last leg of its one-way journey,' Kambiz Fathi of Rochester Institute of Technology told reporters at a meeting of the American Astronomical Society."
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Slowly Pulling Facts from Black Holes More

Slowly Pulling Facts from Black Holes

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  • Slowly Pulling Facts from Black Holes? (Score:4, Funny)

    by Anonymous Coward on Wednesday January 11, 2006 @02:29AM (#14443773)
    Not another story about SCO...

  • Great! (Score:5, Funny)

    by Voltageaav ( 798022 ) on Wednesday January 11, 2006 @02:39AM (#14443796) Homepage
    So even if God does answer my prayers and my boss gets sucked into a black hole, it'll take forever.

  • orbit? (Score:4, Interesting)

    by HermanAB ( 661181 ) on Wednesday January 11, 2006 @02:42AM (#14443811)
    Actually, I don't understand it at all. Why would the matter spiral in. Why won't it stay in orbit? What is slowing the matter down to make the orbit decay?

    • Re:orbit at greater than c (Score:5, Informative)

      by Harmonious Botch ( 921977 ) on Wednesday January 11, 2006 @02:46AM (#14443826) Homepage Journal
      You can't orbit a black hole inside the event horizon without going faster than the speed of light.
    • What makes you think it is in orbit in the first place?

      It's just basic gravity. Things fall down. Even gas. Just look at Earth.
    • Um ... friction? Even interplanetary space in the orbit around a normal star isn't a perfect vacuum, after all; the Earth's orbit is decaying, just veeery slowly (and it would take much, much longer than the projected lifetime of the Sun for such decay to make us spiral appreciably inward.) Around a black hole, you can expect the gas to be relatively dense, and friction to have a relatively fast effect on its orbit. I say "relatively" because, of course, the density is still very low and the time scales

      • Re:orbit? (Score:3, Insightful)

        by HermanAB ( 661181 )
        Hmmm - So friction in the revolving gas could will cause it to heat up and possibly glow, while slowing down its rotation, causing it to cross the event horizon and fall in?

        • Re:orbit? (Score:5, Interesting)

          by Gaccm ( 80209 ) on Wednesday January 11, 2006 @04:04AM (#14444033)
          Hmmm - So friction in the revolving gas could will cause it to heat up and possibly glow, while slowing down its rotation, causing it to cross the event horizon and fall in?

          Yes. The only way something can fall into a black hole is by losing energy to fall it. If it doesn't lose any energy it will keep revolving around the black hole. Same thing with Earth, if Earth was in the middle of a cloud of gas that could eat away at very large amounts of the Earth's momentum, then the Earth could spiral into the Sun. Since that gas isn't there our Earth keeps revolving around the Sun, which is good for us.
          • Since that gas isn't there our Earth keeps revolving around the Sun, which is good for us. - speak for yourself! Where I am right now, I wouldn't mind getting closer to the Sun, maybe even falling in (assuming it is the night time.)
        • Yes! That is, in fact, the usual way in which we see a black hole. The gas is so amazingly hot from friction that it's glowing in the range of X-Rays.

    • Re:orbit? (Score:3, Informative)

      by Cyberax ( 705495 )
      Because of some obscure effects of general relativity, and not because of gravity waves as some people think. I can write you differential equations of, but I'm not going to write them here in ASCII art.

      These effects are extremely weak in our Solar System, but they can be observed in perihellion precession of planets ( http://en.wikipedia.org/wiki/Precession#Precession _of_planetary_orbits [wikipedia.org] ). Right now Gravity Probe B ( http://einstein.stanford.edu/ [stanford.edu] ) is in the final stage of experiment which aims to check

      • Re:orbit? (Score:3, Interesting)

        by lgw ( 121541 )
        Qualitatively, when you get close enough to the event horizon of a black hole, gravity is messing with *direction*. At the event horizon, there is no direction which is away from the center. Near the event horizon (but still pretty close) there's no way to "fall sideways" and thereby orbit, because moving in the direction that would be "sideways" in classical mechanics is actually moving (somewhat) towards the black hole in general relativity.

        Quantitatively, I can't explain it at all!

    • Re:orbit? (Score:4, Informative)

      by DiamondGeezer ( 872237 ) on Wednesday January 11, 2006 @08:00AM (#14444751) Homepage
      Because there's a critical distance away from the black hole below which matter cannot orbit because the orbital speed would be greater than the speed of light. So anything orbiting that reaches the critical orbital radius (which depends on the black hole's mass) will be sucked in.

      In that sense, it shows how differently General Relativity is compared to Newtonian Mechanics.

      See this site [fourmilab.ch] for a visual demonstration and an explanation.

      By the way, I've no idea where "the 200,000 years to hit the event horizon" comes from. According to GR, from our frame of reference it would take an infinite amount of time to hit the event horizon.
      • Because there's a critical distance away from the black hole below which matter cannot orbit because the orbital speed would be greater than the speed of light. So anything orbiting that reaches the critical orbital radius (which depends on the black hole's mass) will be sucked in.

        True, so far as it goes.

        But...

        The Event Horizon marks the surface where Escape Velocity is lightspeed. Circular Orbital Velocity is only sqrt(0.5) times Escape Velocity, so orbital velocity at the Event Horizon is less than li

        • Re:orbit? (Score:3, Interesting)

          by DiamondGeezer ( 872237 )

          The Event Horizon marks the surface where Escape Velocity is lightspeed. Circular Orbital Velocity is only sqrt(0.5) times Escape Velocity, so orbital velocity at the Event Horizon is less than lightspeed.

          Yes, but there's a big difference between escape velocity which is radial, and orbital speed which is tangential.

          As my link above shows, above the critical limit for being able to orbit is outside the event horizon (actually its at 3MG/c^2 expressed in metres from the singularity, whereas the Event Hori

        • it's root(2), not root(0.5), i think, so it's outside the event horizon.

    • Re:orbit? (Score:5, Informative)

      by Phanatic1a ( 413374 ) on Wednesday January 11, 2006 @09:05AM (#14444981)
      Relativity.

      The closest stable orbit around a black hole is at a distance three times the Schwarzchild radius. Closer orbits exist, but they're unstable, the slightest perturbation in them will result in either an escape to infinity or an intersection with the event horizon. At 1.5 Schwarzchild radii, you have the photon sphere; at this distance, orbital velocity equals c, and it's unstable so nothing stays there. Anything closer than 1.5 radii, there are no orbits possible.

  • Metric (Score:2, Offtopic)

    by MacDork ( 560499 )
    177000 Km/hr... or 49166.67 m/s... why is there no metric second?
    • why is there no metric second?

      Pardon, hour-ish metric units of time. Here comes the onslaught of nanosecond wisecracks...

    • Re:Metric (Score:3, Interesting)

      by jfengel ( 409917 )
      Well, you can have kiloseconds, if you want, which is on the same order of magnitude as an hour (well, a bit over a quarter of an hour).

      As you note, we use metric fractions of a second (mill, nano, femto, etc) all the time. Why megaseconds (about 11.6 days) and gigaseconds (31.7 years never caught on), I can't say. Maybe it's because we're all so familiar with hours, minutes, and days, and unlike other metric/English conversions the conversion factors are at least integers, and well known integers at that

    • Re:Metric (Score:3, Interesting)

      by ichin4 ( 878990 )

      Fundamentally, the reason we have no metric unit of time is that there are two lengths of time we really care about a lot -- the day and the year -- and they are not seperated by a power of 10.

      Actually, those metric-crazy revolutionary Frenchmen did try it [wikipedia.org]. They picked the day as the fundamental unit. They then divided the year into 12 30-day months, plus a 5-6 day party at the end.

  • Facts (Score:5, Informative)

    by Anonymous Coward on Wednesday January 11, 2006 @02:49AM (#14443833)
    A few interesting facts about black holes that some people aren't aware of:

    • Black holes emit x-ray radiation and get smaller and smaller until they disappear, or "evaporate".

    • Most black holes are formed from the death of large stars (larger than the sun) that run out of fuel and cannot sustain its nuclear reaction. The star loses the force pushing itself outward and is overcome by the force of its own gravity pulling inward. Eventually, the star has so much gravity and is so compacted that it "eats itself" until there is nothing left but a hole in the "fabric" of space-time, created by the gravity left over from the star.

    • The gravity around the "hole" of a black hole is so strong that NOTHING can make its way back out after a critical distance.

    • Even before crossing the event horizon, though possible to travel away from the black hole, it is not easy. Even light has a hard time getting out, so light being emitted from something almost at the Event Horizon but not yet inside the threshold takes a much longer time to escape and be seen by someone then it would in normal space going at 186,000 miles per second.

    • The Singularity is the true point of destruction, the actual hole part of the black hole, although any object, especially a person, would be long dead before they reached the Singularity.

    • Some black holes are spinning and have several event horizons called the "Ergosphere", "Outer Event Horizon", and "Inner Event Horizon".

    Stephen Hawking's recent concession that black holes do not irretrievably eradicate information after all has garnered much attention. In my opinion, it is refreshing to see the public focused, if just for a moment, on an important conundrum that has fascinated theoretical physicists for three decades, and prompted much conceptual progress. The scientific issues, however, remain much less settled than Dr. Hawking's celebrated wager on the question. He most recently pronounced: "If you jump into a black hole, your mass energy will be returned to our universe, but in a mangled form, which contains information about what you were like but in an unrecognizable state." These ideas are profound and will have a lasting effect on our scientific theories as well as life as we know it.

    • Re:Facts (Score:5, Interesting)

      by Shimmer ( 3036 ) on Wednesday January 11, 2006 @03:09AM (#14443892) Journal
      so light being emitted from something almost at the Event Horizon but not yet inside the threshold takes a much longer time to escape and be seen by someone then it would in normal space going at 186,000 miles per second.

      Not true. The speed of light is a constant, even near a black hole.

      As I understand it, what actually happens to the light emitted by an object approaching an event horizon is that it gets increasingly red-shifted. So an observer at a safe distance would see the object "fade" into infrared and then into ever-longer radio waves until it crosses the horizon.

      • Re:Facts (Score:3, Insightful)

        by penguinoid ( 724646 )
        Not true. The speed of light is a constant, even near a black hole.

        But spacetime is bent quite badly near the event horizon. Light emitted in the appropriate direction would orbit the black hole several times before entering/leaving the black hole, so while the speed of light may be chugging along at 299,792,458 m/s, the distance it travels might not be what you expected...

        • Re:Facts (Score:5, Informative)

          by Wolfbone ( 668810 ) on Wednesday January 11, 2006 @07:35AM (#14444684)
          It doesn't actually matter what direction the light is emitted in - the "slowdown" of light occurs along radial paths too. It is, as you say, due to the badly bent spacetime that this effect is observed, but it's because of the metric structure of the spacetime itself, not the path of the light. In a "normal" (t,r,theta,phi) coordinate system - appropriate to a far away observer - where the Schwarzschild metric describes the spacetime structure surrounding a massive body at the origin, the radial coordinate speed of light (dr/dt) turns out to be (c - 2GM/rc). You get a better picture of what is happening near black holes with more suitable coordinate systems but at least here you can see that if we describe spacetime with a set of coordinates appropriate to "normal", speed of light = c conditions, "the speed of light" really is affected by the massive body.
        • Light emitted in the appropriate direction would orbit the black hole several times before entering/leaving the black hole, so ... the distance it travels might not be what you expected

          That's true, but it's not really germane to the OP's claim that light slows down near a black hole. Assuming for simplicity that the object is directly between the observer and the black hole, then the observer will simply see it fade into infrared.
      • What actually happens is that time slows down near the event horizon as observed from a distance away (outside the gravity well of the hole). It slows down so much that it would taken an infinite amount of time to cross the horizon. This is also the cause of the red-shift.
      • The speed of light would not be at its C constant near a black hole. GR states that light is affected by large bodies of mass. Large bodies of mass warp both space AND time. This experiment was validated (I hate to use the term prove) by the radio transmissions the Cassini space probe shot across the sun towards Earth. The radio transmissions took a longer amount of time than predicted using the C Constant and the distance from the trasnmitter and Earth. This and other experiments, as well as General a

    • Re:Facts (Score:3, Informative)

      by Anonymous Coward
      "Black holes emit x-ray radiation and get smaller and smaller until they disappear, or "evaporate"."

      Don't confuse the x-ray radiation (emitted outside of a black hole) with Hawking radiation, which is the true cause for black hole evaporation.

    • Re:Facts (Score:5, Informative)

      by Anonymous Coward on Wednesday January 11, 2006 @03:11AM (#14443904)
      > Black holes emit x-ray radiation and get smaller and smaller until they disappear, or "evaporate".

      Not really. The black hole itself emits black body radiation and the temperature of a reasonably large hole will be very low, so it's emitting radio waves. As it gets smaller, the temperature goes up, so the emissions will pass through visible light, x-ray and so on. However most large black holes have gas streaming into them from their surroundings, which gets really hot while spiralling into the black hole and this is the part that usually emits x-rays.

      > Most black holes are formed from the death of large stars.

      Unknown. Unproven.
      • As I understand it, it should take infinitely long for any bit of matter to cross the event horizon. Where does this 200,000 years come from? And, why don't we expect to find a shell of matter frozen around the outside of the event horizon?

        I could guess (though they never seem to say) that they're expecting the event horizon itself to grow each time any bit of matter crosses (by whatever means), causing it to engulf just a bit more of the stuff collected just outside, in a positive feedback loop. That s

        • As I understand it, it should take infinitely long for any bit of matter to cross the event horizon.

          No, that's to a distant observer. As you fall in you appear more and more redshifted to him until you reach an infinite redshift at the event horizon and your image appears frozen there. In practice you'd still disappear quickly from the visible spectrum, although in theory you might be visible a few microseconds longer to any observers with an ELF antenna. But in the proper time aboard the ship you fall righ

      • Re:Facts (Score:5, Informative)

        by strider44 ( 650833 ) on Wednesday January 11, 2006 @04:29AM (#14444105)
        I think you and the grandparent are getting a bit confused here on this issue (though it has been a few years since I studied Cosmology, and I may be wrong here, but I *do* try to keep abreast of the journals and recent discoveries when I have time).

        A black hole itself has no temperature and emits no light. It literally can't. Hawking radiation comes from particles from before the event horizon. The actual amount of radiation is insignificant for astronomical black holes since they absorb more radiation from just the cosmic background microwave radiation than is let go through Hawking radiation. It's only really important for quantum black holes.

        Stellar-mass black holes pretty much have been proven to come from the death of larger stars, more than about 3-4 stellar masses. Whether it's proven depends on how strict you are with the word "proof". Supermassive black holes *probably* started as stellar black holes, a long long time ago, maybe not. I'm not sure if anyone knows or has given proof, but if they have then I haven't heard about it. I'd like to though!

        • Re:Facts (Score:2, Interesting)

          by freedom_india ( 780002 )
          A black hole itself has no temperature and emits no light.

          Correction: A black hole "emits" heat, but since heat is transmitted as infra-red travelling at speed of light, it is never "emitted". So you don't get to "feel" the heat or the light. That doesn't mean the blackhole is cold.

          from the death of larger stars

          Stars are dense and hot, and once they shrink/collapse they will be hotter. My guess is the inside of a black hole must be much hotter than the temperate of the core of the star from which it c

        • Re:Facts (Score:5, Informative)

          by Wolfbone ( 668810 ) on Wednesday January 11, 2006 @09:49AM (#14445190)
          "A black hole itself has no temperature"

          Actually it is considered to have a temperature, though it's not the same thing as the temperature of ordinary matter. The analogy of black holes as thermodynamic systems (which I think arose from the study of rotating black holes and Penrose processes) is what motivated Bekenstein historically to suggest that a black hole /should/ emit black body radiation. Hawking set out to prove him wrong and - ironically - discovered that they do indeed.
      • The black hole itself emits black body radiation

        Nope. You are confusing black holes with black bodies. A "black body" is an object which reflects no light, but it emits its own radiation. A "black hole" is an object which emits no radiation at all.

        A black body emits radiation unless its temperature is absolute zero. It need not be black to the human eye, black bodies used in laboratories often are glowing red hot. Black bodies used in labs are usually formed by a cavity with a very small hole. The energy e

        • In this way, the anti-particles will be going into the black hole, slowly cancelling its mass while the particle radiates away.



          Even anti-particles still have a positive mass. They cannot cancel out anything. The black hole loses mass by what is radiating away, not by what is dropping back into it.

          • "Even anti-particles still have a positive mass. They cannot cancel out anything. The black hole loses mass by what is radiating away, not by what is dropping back into it."

            In the presence of an event horizon, though, occasionally one member of a virtual pair will fall into the black hole while its partner escapes to infinity. The particle that reaches infinity will have to have a positive energy, but the total energy is conserved; therefore the black hole has to lose mass. (If you like you can think of t

    • Re:Facts (Score:5, Interesting)

      by Black Parrot ( 19622 ) * on Wednesday January 11, 2006 @03:32AM (#14443956)
      > The Singularity is the true point of destruction, the actual hole part of the black hole

      No, the event horizon is the methaphorical "hole in space".

      Lots of physicists doubt that singularities even exist. Singularity essentially means "the math broke", a result of applying GR at scales where QM effects almost certainly dominate. If we ever get a theory that unifies GR and QM, we might discern what actually happens at the center of a black hole.
      • >> The Singularity is the true point of destruction, the actual hole part of the black hole

        > The event horizon is the methaphorical "hole in space"

        Yeah, but an object isn't destroyed just by crossing the event horizon. In fact, for a sufficiently large black hole, you could cross the event horizon without noticing anything disruptive. Inside the black hole, GR works fine until you get near the singularity. What would actually kill you on the way down is the stretching effect of tidal forces.
    • Black holes emit x-ray radiation and get smaller and smaller until they disappear, or "evaporate".

      OK.

      The gravity around the "hole" of a black hole is so strong that NOTHING can make its way back out after a critical distance.

      Haven't you just contradicted yourself?
    • There is a question I have been wondering for some time about black holes, so karma be damned I shall ask it in hopes of some response. Is it possible for light to actually orbit a black hole at a certain radius? Could energy "build up" around this radius and slam into and annihilate whatever crosses into the black hole?
      • Is it possible for light to actually orbit a black hole at a certain radius?

        Yes, but you are unlikely to ever see it. The only possible orbital radius is exactly the same as the event horizon. Larger, and it will spiral out of the hole. Smaller, it's already in and will fall in the singularity.
    • The scientific issues, however, remain much less settled than Dr. Hawking's celebrated wager on the question.

      Um, I think he's a Professor [hawking.org.uk].

    • Re:Facts (Score:3, Interesting)

      by retro128 ( 318602 )
      Black holes emit x-ray radiation and get smaller and smaller until they disappear, or "evaporate".

      Does all the matter of a black hole bleed off as X-Ray radiation? Or is all of it just folded up into the singularity, which should be theoretically impossible to get to since spacetime is infinitely warped around it?

      Could the "big bang" have occurred when a singularity in another universe isolated itself and folded into this dimension? Could the whole universe be a spacetime bubble? Stuff to think about...
    • "If you jump into a black hole, your mass energy will be returned to our universe, but in a mangled form, which contains information about what you were like but in an unrecognizable state." These ideas are profound and will have a lasting effect on our scientific theories as well as life as we know it.

      It all sounds a bit string-theory-ish to me.

    • Re:Facts (Score:2, Insightful)

      by johno.ie ( 102073 )
      Your comment is purely based on the theories of Stephen Hawkings. I've read a lot of his work and I think he is mostly full of shit. For some reason he has been put on an intellectual pedestal by his peers in the field of theoretical physics. I don't believe that this is for the right reasons though, but I won't speculate what the reasons actually were. I think his theories are having a harmful effect on physics as a whole, because (1) like i said above, he's full of shit, and (2) any new breakthroughs that

    • Re:Facts (Score:3, Informative)

      by tgrigsby ( 164308 )
      To clarify:

      * Black holes emit x-ray radiation and get smaller and smaller until they disappear, or "evaporate".

      The time taken to do this for any appreciably large black hole is on the order of trillions of years. Theoretically speaking, of course. Black hole evaporation only really makes sense in high energy particle collisions.

      * Most black holes are formed from the death of large stars (larger than the sun) that run out of fuel and cannot sustain its nuclear reaction. The star loses the force pus

  • Big distance but useless figures (Score:5, Interesting)

    by Red Flayer ( 890720 ) on Wednesday January 11, 2006 @02:50AM (#14443837) Journal
    310316400000000 km is the last leg of the journey?

    FYI, that's 2,074,335.22 Astronomical Units, or 32.8 Lightyears, or about the distance from Sol to the Cepheids. Dang.

    Too bad they don't specify how far out (radially) from the event horizon the last leg starts. Or even loosely define what 'last leg' means in this case.

  • Wikipeding? (Score:3, Informative)

    by bubulubugoth ( 896803 ) on Wednesday January 11, 2006 @03:06AM (#14443884) Homepage
    So, if there is a "googling" action, also is there a wikipedin action?
    The Wikipedia entry about Event Horizon [wikipedia.org] has an interesting "faq" about, orbitig the event horizon and sticking you hand into the event...
    Also the wikipedia companion, talks about Stephen Hawking [wikipedia.org] saying that no "event horizon" can be formed at a black hole... This article needs edition... :)
    Good reading before a good sleep...
    Btw, there is a neat animation about a neutron star X-ray burst [nasa.gov]


    enough of karma whoring...
  • Wait...I'm confused. Is this another John Dvorak article, or what?
  • You'd be messing with the Phantom Zone, and we'd perish under the rule of the great General Zod!

  • It hurts less... (Score:3, Funny)

    by Black Parrot ( 19622 ) * on Wednesday January 11, 2006 @03:36AM (#14443964)
    ...if you pull the facts out quickly.

  • The article isn't very clear on why matter traveling rapidly toward a black hole would still take a long time to fall in. I assume they are refering to the gravitational time dilation effect. For someone looking from far away, clocks near the black hole appear to run slower, and in fact to stop at the event horizon. Conversely, someone falling into the black hole (ignoring for the moment that he would in fact be ripped apart by tidal forces) would see the entire history of the universe played out above hims

    • Conversely, someone falling into the black hole (ignoring for the moment that he would in fact be ripped apart by tidal forces) would see the entire history of the universe played out above himself as he fell in.

      Well not quite. Whether he'd be ripped apart would depend on the rate of change of the gravitational field strength with distance. He'd last longer if it were a larger black hole, and if it were spinning. Also he'd see the entire future of the universe play out before him. It would also appear,
    • Black Holes are just that, holes in space-time. While, to an outside observer, time appears to stop at the event horizon that doesn't mean that time stops for the person going into the black hole. All it means is at that point the object is no longer moving forward in time with the rest of us. The person/object could just as easily be moving backwards in time or broken free of time, both of which are plausible explainations if you look at the structure of space-time in an Einsteinian manner.
  • There are way too many jokes to make about reaching the "point of no return" while being in a "black hole" to choose just one.
  • ..if someone tried to steer a spaceship into a black hole, from their perspective? Would the rest of the universe seem to freeze to them until they died of old age? Or would they actually be destroyed by some force inside the hole itself?

    • Re:What would happen.. (Score:5, Informative)

      by Gleng ( 537516 ) on Wednesday January 11, 2006 @06:05AM (#14444421)
      Or would they actually be destroyed by some force inside the hole itself?

      Have a read about Spaghettification [wikipedia.org].

      • From: Syd Midnight
        Subject: Re: FAQ this shit!
        Date: 1999/07/13
        Message-ID: #1/1
        X-Deja-AN: 500445758
        Content-Transfer-Encoding: 7bit
        References:
        X-Accept-Language: en
        Content-Type: text/plain; charset=us-ascii
        X-Trace: news.onlynews.com 931856756 216.144.10.111 (Tue, 13 Jul 1999 02:05:56 PDT)
        Organization: http://www.nls.net/mp/syd [nls.net]
        MIME-Version: 1.0
        NNTP-Posting-Date: Tue, 13 Jul 1999 02:05:56 PDT
        Newsgroups: alt.tasteless

        GRay wrote:
        >
        > Dave wondered:
        >
        > > ObT: MotorGimp Stephen Hawking says that for a

  • Reuters was only off by 99.99% (Score:4, Interesting)

    by xmark ( 177899 ) on Wednesday January 11, 2006 @04:52AM (#14444179)
    "The one-way journey from the heart of a galaxy into the oblivion of a black hole probably takes about 200,000 years..."

    "...scientists figured that material moving at 177 000km an hour would still take eons to cross into a black hole."

    Eons are the largest division of geologic time. There have been just four of them since the formation of the Earth. In rough terms, that's a billion years each.

    Maybe the reporter can get a job working on unit conversion for the next Mars probe. (*cough*)

    • Re:Reuters was only off by 99.99% (Score:4, Interesting)

      by Phanatic1a ( 413374 ) on Wednesday January 11, 2006 @09:13AM (#14445009)
      From our frame of reference, matter moving at 177,000km an hour would still take eons to cross into a black hole. In fact, we'd never observe it doing so, by the time it crosses the event horizon any radiation from it will be redshifted to infinity.

      From the frame of reference of that matter, entry into the black hole will take but an instant.

      This is relativity. Always specify your FOR.

  • What they don't mention (Score:4, Interesting)

    by merlin_jim ( 302773 ) <{James.McCracken} {at} {stratapult.com}> on Wednesday January 11, 2006 @11:01AM (#14445599)
    Is the scientific reason that gas can take 200,000 years to be pulled in by the most gravitationally massive type of object possible in the universe.

    It is for two reasons; first off, gravitational time dilation - time gets slower the closer you get. The gas is orbitting the black hole, which also adds relativistic time dilation.

    The gas, in fact, probably orbits at just under escape velocity - thanks to a fun little effect called (IANAA) relativistic frame dragging - basically the black hole drags the fabric of spacetime around itself - and objects within about 1.5 radii of the event horizon start feeling the effect - effectively locking them into a particular path. One way to look at this is to say that time is swallowed by the black hole same as mass - and therefore objects in the vicinity of the black hole fall in because their time arrow points to its dark, dark heart.

    This frame dragging should happen at speeds approaching the speed of light - and require comparable amounts of energy to change your frame. There's even some theory that infalling matter will follow gravitational field lines, like you get around a magnet - but I'm not sure how much I believe that...
  • Within a boundary of about 50 miles from the black hole center, gravity is so strong that not even light can escape its pull

    I found this to be the most interesting...and here I always thought if you were anywhere near (as in hundreds of thousands, if not millions of miles) of a black hole you would be screwed...but apparantly, it is only on the 50 mile marker that you are totally hosed...I mean with our technology we would be hosed at much farther distances...but if we ever have a chance to travel at j
    • Even if we could travel at say, .75c, anything "near" a black hole any living thing would be hosed. The g forces of orbit insertion would likely tear our fragile bodies and crafts apart. Additionally the Xrays, gamma particles, and other nasty radiation would cook and fry everything.

      Achieving neccesary velocity to not fall into a black hole would be easiest part. Even if we got into some kind of orbit, at near C speeds, you'd never leave. You'd need even closer to C speeds, and if you were near the ev

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"What man has done, man can aspire to do." -- Jerry Pournelle, about space flight

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