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Space

Plans To Peer At A Black Hole's Event Horizon 77

Posted by timothy from the jimmy-hoffa-but-all-distorted dept.
mattorb writes: "From the press release: "Scientists have designed and succesfully tested a new type of X-ray telescope that, when fully developed and placed in orbit, may capture the first images of a black hole and resolve images of nearby stars as clearly as we can see our own Sun today. The report is published in the Sept. 14 issue of Nature."

Go here for more information on the project, which is known as the Micro Arcsecond X-ray Imaging Mission. Note that the proposed MAXIM mission would launch after 2010."

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Plans To Peer At A Black Hole's Event Horizon More

Plans To Peer At A Black Hole's Event Horizon

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  • Re:MAXIM? (Score:1)

    by Anonymous Coward
    ...but will they put a hot chick with big tits on the cover of the telescope too?

  • Re:Check, please? (Score:1)

    by Anonymous Coward
    I mean, come on: the second phase (100-nanoarcsecond res.) calls for keeping "up to 33" spacecraft flying in formation with a precision of 20 nanometers?!?! H-H-How? Or rather, How Much?
    Actually, you don't have to control their orbits to 20 nm precision. You merely need to know (at any given time) their relative location wrt eachother within 20 nm, so you can correct for it. That can be accomplished using a highly accurate laser radar. Laser radar was one of the key enabling technologies of the SDI program, so a lot of research was done in the area and it is starting to find non-military applications such as this.

  • Re:Wait a second here... (Score:3)

    by Anonymous Coward on Thursday September 14, 2000 @02:50AM (#780596)

    ...until physics gets to the point where we can truly prove that Relativity as Einstein theorized is basically unchallenged it could be a waste of money simply to search for black holes.

    Up to now, there is no experimental evidence that GR is wrong. Theories cannot be proven to be right, they can only be disproven. Experiments can only confirm a theory or invalidate it, in the case of MAXIM, the finding of a black hole (or more precise, the finding of an event horizon) would be another confimation of GR. Consequently, you would have do define a level of confidence of GR, that you regard as sufficient to fund the search for black holes. More precise, you would have to suggest experiments suited to confirm GR, that would be prerequisite for funding black hole research. I doubt that you can find such experiments (they have to be less expensive than MAXIM) that havent already be done. After all, scientists like to pick the low hanging fruits first, as much as anyone.

  • Detecting black holes (Score:4)

    by Anonymous Coward on Wednesday September 13, 2000 @09:00PM (#780597)
    Black holes can be detected (in theory of course) by looking for the emissions they give off. The theory goes (extremely roughly) that as individual particles reach the "edge" (event horizon?) of the black hole (crossing this line means you never come back), some of them are torn apart, half of the particle going in, half going out, and some energy is released during this fission. It is these fissions at the edge that make a black hole appear to give off energy, and make it detectable.

    That type of radiation is called Hawking Radiation (after Stephen Hawking, naturally). However, this isn't what lets us detect black holes, as Hawking Radiation is ridiculously faint. Black holes can be detected by the X-Rays that they "inadvertantly" produce. When matter is falling into a black hole it is accelerated, heated, and compressed to such a degree that it gives off large amounts of X-Rays. I believe the first black hole we detected (again, assuming black holes exist), was Cygnus X-1 (or cygnus something), and we detected it by the x-rays it gave off.

    Another method of detecting black holes is to look for graviational lensing effects. Because black holes are so massive, they bend the fabric of space time. (Imagine a sheet suspended in the air. Place marbles on the sheet. The marbles make depressions on the sheet, like stars make "depressions" in space-time. A black hole is so heavy, it's like dropping something that is the size of a marble but with the weight of a bowling ball onto the sheet. The sheet bends A LOT, and it actually will have a hole where the singularity is.) Light travels in a straight line, so if space-time curves, light also curves with space-time. Gravitational lensing was proved during a solar eclipse. Astronomers observing the eclipse noted that they were able to see stars that should have been blocked by the eclipsed sun. The sun's gravitational field caused enough "lensing" so that stars directly behind the star could be seen to either side of the star. So, if we find something out in space that is causing a LARGE amount of gravitational lensing, but we can't see anything, there's a chance it's a black hole. At that point we normally observe it more to determine if it is or isn't a black hole.

  • My immediate thought on seeing the headline was "Who the hell would they be peering *with* out there?"

    Imagine the stock market rush if people think Verizon is going to merge with the Vorlons...
  • Dude, I'm still pretty psyched about PHP and my digital camera.
  • The details of even the proposed pathfinder mission (I can't find any details for the main mission) are fairly mind-blowing. The pathfinder is effictively an X-ray telescope with a 450km (300 mile) focal length. This is two spacecraft flown in formation at this distance with their relative positions and angles controlled and sensed to hideous precision.

    Of course pointing the telescope at a new target takes a while.
  • It's ok to get excited, but let's keep our pants on over this.

    There's still substantial doubt (and no hard evidence) that black holes actually exist. It's unclear if this experiment will lead to more evidence either way, but we'll have to wait and see what we get after wading through the pop-appeal stories.
  • Ok who else mis-read it first time and thought it said "Peer to Peer At A Black Hole's Event Horizon"? My mind boggled at the thought.

    The reality is still exciting though...

  • Wrong kind of peer (Score:3)

    by samael ( 12612 ) <Andrew@Ducker.org.uk> on Wednesday September 13, 2000 @10:02PM (#780603) Homepage
    Was I the only one who read that and wondered why you'd need a peering arrangement on an event horizon?

    I mean, surely your data would take longer to retrieve?
    _____

  • Obviously, I have something wrong. So how do mirrors that reflect X-rays work?

    You're absolutely right that an X-ray photon will rip electrons (even core electons) out of an atom, and will not therefore be reflected. However, at very low angles of incidence (a few degrees at most) X-rays are reflected. (I think this is because they interact with many atoms at once, rather than just one -- quantum effects come in here, and I can't remember the details :( ). Anyway, whats this means is that you can build an 'X-ray lens' by nesting lots of carfully arranged cylinders, whose axis points in the direction you're looking. X-rays reflect off the inner surface of the cylinder onto your detector at the back of the telescope.

    This isn't the only way to do it; a slightly weirder method is to put a Uniformly Redundant Array where you would normally put the lens. By selectively subtracting X-rays from the source image, this result in the detector seeing convolution of the image (like a fourier transform) which can be deconvolved to the original image. see here [www.sron.nl] for an introduction to URA high energy telescopes...

    URA telescopes like BLAST have the disadvantage that you reduce their sensitivity due to blocking half the incident X-rays. On the other hand, I think you can use them do detect higher energy X-rays than low-angle reflection telescopes. But someone who actually works on these things will probably contradict me :)

  • Re:Detecting black holes (Score:3)

    by PhilA ( 18734 ) on Wednesday September 13, 2000 @11:14PM (#780605) Homepage

    I may be wrong (so all those astophys grads can correct me if they want) but I don't think Hawking radiation works quite like that.

    No, you're right. He's talking about X-ray emmission from infalling matter, which was predicted long before Hawking radiation was. I don't believe anyone has actually seen Hawking radiation yet --- in a black hole of any size it's very small indeed; you only get significant amounts from very small black holes. Indeed, as the black hole looses mass to Hawking radiation, the radiation rate increases (exponentally? Can't remember the power...), this means you should get an explosion of radiation as the black hole evaporates entirely, leaving a naked singularity behind it...

    Possibly fortunately for us, the evaporation time for a black hole resulting from a stellar collapse is on the order of 100-1000s of billions of years, and it'll only start after the influx of mass into the black hole falls below the rate of Hawking radiation. This won't happen til the famous heat death of the universe :)

    Its possible that micro black holes could be left over from the formation of the universe, and these might evaporate during the lifetime of this galaxy. But no-ones seen it happen yet...(AFAIK, gamma ray bursters have the wrong time-signature to be evaporating black holes)

    Phil
  • > one of the major science missions of the Next Generation Space Telescope is to probe "the era when galaxies were young" (as the hokey PR material used to say).

    Cool. If it can see back long enough ago and far, far enough away, we might be able to find out what really made sweet little Anakin turn to the dark side.

    --
  • Oh, I thought that headline was -
    Plans to Pee at a Black Hole's Event Horizon
    Frat boys and their pranks, and all that.

    --
  • Exactly. I saw the headline and thought, "Gee. What are they doing, using some kind of singularity effect with really tiny black holes to make high-bandwidth FTL links for a system-wide network so that astronauts on the Mars mission can publish their findings and the AOL users can have good latency to their server?"
  • Didn't they listen to their mothers? Mine always told me I could go blind if I stared too long at a black hole.
  • Sounds very impressive, definatly. Compared to the Hubble, it's completly next-generation. Learning the secrets to black holes may in fact lead us to faster than light travel. After all, black holes are so strong, they trap light too.

    You'd have to wonder, though, if MAXIM is being planned, what's up with Chandra? Did it not live up to expectations? Has me wondering if MAXIM will too...

    It brings up some very interesting possabilities, too, though... If anything, we'll at least find out where all those socks go that you swear go into the dryer, but never come out :-)

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  • You Know You've Been A Dot-Commer Too Long When... (Score:3)

    by Tackhead ( 54550 ) on Wednesday September 13, 2000 @09:05PM (#780614)
    You see "Plans to Peer at a Black Hole's Event Horizon", and the first thought you have is "who the hell is Blackhole.com or Eventhorizon.com, what do they have to do with P2P, and why haven't I heard of them before?!?!"

  • Hawking radiation (Score:4)

    by Enoch Root ( 57473 ) on Thursday September 14, 2000 @05:28AM (#780615)
    Er... Physicist to the rescue.

    Hawking radiation comes from localized fluctuations in the electromagnetic field intensity of the void. That is to say, even though on average a certain area of empty space beyond the event horizon is, say, E_0, small localized fluctuations may result in, say, differences of +/-1eV.

    Now, given that photons are the carriers of the electromagnetic force, you can consider the -1 eV and +1 eV as two virtual photons. These are not a photon and an anti-photon: they're a photon of positive energy, and a virtual (i.e. whose longevity is less than Plank's time) photon of negative energy. Or, if you prefer, if you set E_0 to 10 eV, then the first photon has 11 eV, and the second 9 eV.

    Now, the positive photon may have enough energy to escape the black hole's pull; the negative photon, OTOH, automatically does not. It falls into the black hole, where it anihilates with a photon caught inside.

    End result: the black hole is 1 eV poorer, and a 1 eV photon has been emited by the space around the black hole. This, in effect, means energy somehow 'escaped' the black hole, and can be measured as radiation.

    It's a nifty concept, but unfortunately, its intensity pales in comparison to the radiation emitted by matter falling into the black hole as it is accelerated.

  • for a great look at the wonderful wierdness of black holes, the fabric of space, and worm holes grab a copy of:

    "Black Holes & Time Warps: Einsteins Outrageous Legacy" by prominant physicst Kip Thorne. (There's even a forward by Hawking :)

    It's a great non-technical look at all really fun stuff in the cosmos (both fact and theory)

    You can look at (and buy) the book at FatBrain by clicking: here [fatbrain.com]
  • Just to clarify some points made here...

    The reason we can (or at least should) see black holes has to do with quantum pairing of all matter, and quantum flux.

    There is matter coming into, and going out of being constantly. This matter comes in pairs of matter and anti-matter, and as soon as they interact... poof, gone. But say this matter/anti-matter pair comes into being right on the edge of the even horizon of a black hole. One side of the pair would slip into nothingness, to be crushed by the black hole, and the other... due to very complex math (hehe) gets shot off VERY fast and with a LOT of energy away from the hole.

    This is what we would see, a glowing halo of sorts around the black hole. These particles are of such high energy, x-ray to gamma ray or so, we need VERY sensitive detection devices to see them.

    Explain that pretty well? No? Stfu.
  • > Because black holes are so massive, they bend the fabric of space time.

    Actually, everything bends the fabric of spacetime to some extent. This effect is quite noticable - it's what's keeping you on your seat right now, but with sensitive equipment you can even detect the bending of the fabric of spacetime caused by passing cars outside the physics lab.
  • Chandra is alive and well as you can tell from this link:

    Chandra Discovers Missing Link Black Hole [cnn.com]

    I hope I did that html right since the preview button doesn't seem to be working.

    Kintanon
  • Well considering fiber optics are simple pulses of light, how could it not carry information? Even basic code should be able to be transfered... simple standards like Morse and binary. On another note, I wonder how close this will bring us to developing the most awesome of phenomenons at our own will. Human waste could possibly cease to exist. Just thinkin.. that's all.
  • Re:"You see "Plans to Peer at a Black Hole's Event Horizon", and the first thought you have is "who the hell is Blackhole.com or Eventhorizon.com, what do they have to do with P2P, and why haven't I heard of them before?!?!"

    "And who is the holding company, "Black Hole", who owns Event Horizon.com?!?! I never heard of them. I better turn on CNBC Squakbox and check out if the kahuna has news on movement at Black Hole.

  • And who thought there'd be Who Wants To Be A Millionaire and Pokemon and Veronica's Closet and Barney and the DMCA?

    Man, those poor saps back in olden times didn't know what they were missing!

    -Pete

  • Will it be able to see through clothes like x-ray spectacles can.

    If so I can imagine the techies running this thing, pointing it earthbound during the late shift and feasting there eyes on some lovely girlies, whose clothes offer no protection against its steady stare ........... ;)

  • This sounds like a troll, but I'll bite.

    Excuse me? I don't want to start a flamewar here, but I didn't use the term "daydreaming" anywhere in my post. I can only suppose you're talking about the fact that I called the NGST slogan "hokey PR" -- I called it this not because the NGST is unjustified scientifically, but because it struck me as a silly slogan. I'm a graduate student in astrophysics, for chrissakes.

  • high redshift galaxies, etc. (Score:3)

    by mattorb ( 109142 ) on Wednesday September 13, 2000 @09:27PM (#780625)
    The formation of galaxies is definitely a topic of major research interest; one of the major science missions of the Next Generation Space Telescope is to probe "the era when galaxies were young" (as the hokey PR material used to say). Keep in mind, though, that the problem is not just one of building a bigger telescope, but of building a telescope that is sensitive in the right wavelength regimes : the farther away from us you look (and hence the farther back in time you're probing), the more "redshifted" things become; their light is shifted to longer and longer wavelengths. So to probe the early galaxies, NGST has to be sensitive in the infrared region of the spectrum -- which brings up a whole slew of complicated design problems. (The Earth glows in the IR, for one thing, so a near-Earth orbit isn't practical -- the NGST will be nowhere near us, and hence impossible to service once it goes up.)
  • No, not the only one. I was trying to figure out the point of peering at an event horizon. Like faster-than-light communcations or something...

    --

  • The linked-to article says that the X-ray telescopes worked by bouncing the X-rays off of a mirror. With my limited knowledge of physics, I thought that reflection required a photon being absorbed by an electron, which went to a higher orbital and then back down again, emiting back out the absorbed photon; I also thought that any time a X-ray photon interacted with an atom, it ripped the electron right out of the atom's shells and ionized it. Thus, I've always thought that it was impossible to reflect X-rays.

    Obviously, I have something wrong. So how do mirrors that reflect X-rays work?


    Suppose you were an idiot. And suppose that you were a member of Congress. But I repeat myself.
  • Theoretical Physics and some of this stuff that you call daydreaming is not detrimental to society and it is not a waste of your money. Just because it is happening a couple million light years away doesnt mean that it doesnt involve you.

    <Personal Oppinion>Because I dont follow a major religion, this is what i consider searching for God. Life, The Universe, and Everything... It all ends up linking itself somehow with you. I just wish that people would be less concerned with making a dollar and pay a little more attention to learning about themselves and their surroundings.</Personal Oppinion>

  • Everyone is talking about looking at black holes, but does anyone know if we have the ability to study the hubble horizon with the telescopes that we currently can build? What kind of research is going on concerning that swampy reigon of space where we can see galaxies forming?

    Just curious...

  • Um, which of the editors replied? Looked to me like timothy offered no comment on mattorb's story submission.

    From the article:

    With 100 microarcsecond resolution, astronomers could image the coronae of nearby stars, seeing the actual disks of other stars which appear now only as points of light.
    This same sentence appeared both in the "Background Information" section and the press release. If they're not going to use the scope to view regular stars, why do they mention such capabilities, twice?


    If you're not wasted, the day is.

  • I believe that link discusses the subject to which you are referring. This guy [nec.com] and his friend [nec.com] performed an experiment in which the group velocity exceeds the speed of light. As I understand it, group velocity is an idealization: it is the notion of the velocity of a pulse, not a photon. As the article explains, in some sense they've gotten the pulse to traverse a medium faster than c. But, "no object or information has been made to travel superluminally."

    So, surprisingly enough, nearly seventy years' worth of physics has not been suddenly and summarily disproven.


    If you're not wasted, the day is.

  • Learning the secrets to black holes may in fact lead us to faster than light travel. After all, black holes are so strong, they trap light too.

    Not to be flippant, but nothing we know (think) about black holes points to superluminal travel. Of course, by "we" I mean "I". If I missed something please fill me in.

    You'd have to wonder, though, if MAXIM is being planned, what's up with Chandra? Did it not live up to expectations?
    When it comes to research resources like big-ass telescopes, the more the merrier.
    It brings up some very interesting possabilities, too, though... If anything, we'll at least find out where all those socks go that you swear go into the dryer, but never come out :-)
    True dat.


    If you're not wasted, the day is.
  • I get suspicious whenever I hear about a huge, seemingly sci-fi project, and nobody mentions any cost estimates. I think I read the whole article, but didn't see any dollar signs. Did anyone else?

    I mean, come on: the second phase (100-nanoarcsecond res.) calls for keeping "up to 33" spacecraft flying in formation with a precision of 20 nanometers?!?! H-H-How? Or rather, How Much?

    Is this a vapor dream, or has someone actually checked the $important numbers?


    If you're not wasted, the day is.

  • For those impatient.. just check out the already 2 existing Xray able orbital observatories. (sometimes I wonder what would this 3 rd is for, but hey better hardware I guess)

    Chandra some specs and the main pics directory.
    http://spaceflight.nasa.gov/shuttle/archives/sts -93/cargo/chandra_cargo.html
    http://chandra.nasa.gov/

    XMM is found here... but no pics???
    http://www.estec.esa.nl/spdwww/xmm/factsheet.htm l
    http://www.estec.esa.nl/spdwww/xmm/html/spacecra ft.html

    Meanwhile the International Space Station is going on... Don't forget to reserve your seats!
    http://spaceflight.nasa.gov/station/index.html

  • Stephen Hawking: I call it a Hawking hole.
    Fry: No fair, I saw it first!
    Stephen Hawking: Who's the journal of quantum physics going to believe?

  • it could be a waste of money simply to search for black holes.

    I disagree because it's not the fact that we find the black holes because we can. We look for them because of what we can learn from them. Black holes and worm holes bend spacetime to such a degree that they may open up ideas for future space travel. Theoretically, physics does allow objects to travel from Point A to Point B faster than light in a straight line by taking a short cut through black holes and worm holes. So if we can do that, then we'll have learned something from black holes that will not only revolutionise space travel but the way we look at physics.

    Self Bias Resistor
    "Anyone who can contemplate quantum mechanics without getting dizzy hasn't understood it." -Niels Bohr

  • It's not as impossible as you think it is to get 20 nanometers precision.

    Deep Space 3, nasa's light interferometer mission is looking at micrometers precision already.

    The point is that in space, there is no friction, so it's almost your dream "inertial" frame. It's ironic that it is easier to control the attitude (i.e. orientation) of something in space than on Earth.

    The trick is to know where things are relatively to each other. The way to do this is for the spacecraft to "ping" each other with pulses of x-ray (to get the smallest wavelength possible)
    and then figure out the relative orientation from the "out-of-phase-ness" of the pings. Each S/C must have a precisely calibrated atomic clock of course.

    Also, the spacecraft must be extremely stiff (since sloshing will fsck-up the attitude control responses), which is not hard since they are essentially mirrors with thrusters strapped in. I'll imagine they will use plasma thrusters, which can be controlled for extreme small thrust bursts, and uses solid fuel so there will be no sloshing in the tanks.

  • The ISS (aka "Freedom") was already vaporwared 10 or 9 years ago. Other than that, I know how you feel, dude.

  • However, if the 'scope will be put to good use for more than _just_ black hole chasing it may be fine.

    When pointed toward the earth, MAXIM will be able to use x-ray diffraction to produce a working "X-Ray Specs" effect which will see through people's clothes.

    Is that OK?

  • ...explosion of radiation as the black hole evaporates entirely, leaving a naked singularity behind it...

    What is the difference between a black hole and a 'naked singularity'? I've heard of these before but never known what they were.

  • Re:Detecting black holes (Score:5)

    by NoNeeeed ( 157503 ) <slashNO@SPAMpaulleader.co.uk> on Wednesday September 13, 2000 @09:54PM (#780641)
    I may be wrong (so all those astophys grads can correct me if they want) but I don't think Hawking radiation works quite like that.

    What happens is you have virtual partical pairs (a partical and anti-partical) which blip into existence and then anialate soon after. They have very short lives. However, if a pair form on the event horizon, one half gets drawn into the hole while the other gains the same (but opposite) energy and is ejected out into space.
    That was how I understood it, but if I'm talking out of my 'black hole' feel free to correct me.

    By the way, always try to reference quotes where the origin isn't obvious, couldn't find your quote on the MAXIM website so I presume you got it from somewhere else.
  • I remember reading about a wide-scale laser inferometer that was being built in the 'late 90s' to help discover planets around other stars. Was this ever completed?

    And for MAXIM, could this be used to get more information about suns with planets? So far, there's been a fair number of jovian-sized planet discoveries, but nothing in the terrestrials... Now that would be a breatkthrough!

  • Better than 2061 or 3001..

    (any sufficiently advanced choice of year for a big science project is indistinguishable from those in Clarke's books. 8-)

    --

  • Why not just buy a Sony Camcorder with the IR filter/effect (Nigthvision) :P

    Of course people like me don't need a x-ray telescope to see naked women... that's what I've got a modem and an internet connection for ;P
  • Actually Hawking Radiation has nothing to do with fission of particles entering a black hole's radius. It comes from particle-antiparticle creation at a very close distance to the horizon, and one of those being subsequently trapped in the BH before re-annihilating.
  • Whenever a science article comes up, I rush to read it so that I can discuss some interesting topics will relatively intelligent people. Censorship and corporate brutality get old real fast for me. So, I see an article like this and I rush to see what people say.

    And every time its one person saying "what is this?" and 15 people replying to it. Nobody actually discusses the article...its like a proving ground where people compete to correct another persons perception of the concept. What happened to the topic at hand?
  • but then again what about 10 years AGO? did YOU think there would be an international space station? \ how about news stories centering around computers every other night? or how about nanotechnology coming of age? one GIGAHERTZ machines? personal communications equipment ala star trek? i don't know.. i still think this right now is really exciting. 10 years from now.. now that'll be interesting too, i hope. assuming ebola doesn't kill us all, that is.... :)
  • of COURSE there's substantial doubt; if there wasn't, i'd be worried that our science community is a bunch of neophyte morons who jump on any "pop-sci" possible. but the thing is, that of all the wierd things in physics (which includes quantum physics and its propensity towards complete and utter illogically strange things), black holes aren't that wierd in comparison, and if they can be proven to exist (without say landing a man on them... sorry, there was a joke there but i guess it wasn't funny so ON with my rant) it could open up whole new doors in theoretical physics. not to mention the fact that something as advanced as this could do wonders for the telescope-usin' scientists in general, even if the only thing it would do is add one more telescope to the sick time sharing system they have going on. as for this being vaporware? i thought the ISS was too, but hey... there it is. neutered, yes. but it's there. i think the entire point is.... holy crap, let's drop our pants and run around excitedly for a few days and act hysterical! woohoo.
  • every time something this cool happens, i get more of that wonderful "i'm living in the future" feeling.... maybe it's me, but once in a while don't you feel excited about NOW? i mean, only a few years ago black holes were just some ludicrously unprovable idea. now we're gonna LOOK at them, or at least their even horizon. neat-o.
  • I don't know how relevant this is, but we just had an article (too lazy to link, sorry) about how the speed of light barrier was broken (by light, ironically). If this is true, doesn't it shoot many physics theories down the drain? And if so, how would if affect this one?

    Sure, it doesn't shoot down black holes. But it may possibly shoot down the definition.
  • we can but only hope.

  • MAXIM? (Score:3)

    by Crinos ( 201310 ) <neojedi@@@yahoo...com> on Wednesday September 13, 2000 @09:58PM (#780652)
    Am I the only one who notices that the government is namimg this project after a men's magazine? Or perhaps the only one who cares?
  • I thought it meant Event Horizon was being released again. That movie should be sent into a black hole. Or am I thinking about Sphere again. Well, I just woke up, so that probably had something to do with it.
    Dustin Hoffman - IN SPACE!!!

    -----
  • By coincidence, the astronomy picture of the day [nasa.gov] from nasa happens to be a black hole. The article has some nice links on general theory behind them as well.

    ---

  • NASA wants to start a MAXIM (aka, a mens magazine) project so that they can see a BLACK HOLE. :)

  • A black hole of mass M solar masses will have a temperature of 6*10^-8 / M Kelvin, and a lifetime of 10^71 * M^3 seconds, so don't wait around for one.

    Of course, for a smaller black hole these quantities become a bit more realistic - a black hole with the mass of a small mountain (say 10^11 kg) has a lifetime of less than the age of the Universe, but it does have a temperature of 10^12 Kelvin, which is roughly equal to the rest mass energy of a photon.

  • ... is this [bbspot.com] new graphics card from Matrox :)

  • Re:Detecting black holes (Score:3)

    by flatpack ( 212454 ) on Wednesday September 13, 2000 @09:51PM (#780658)

    Actually, IIRC Cygnus X-1 was the first detected because it was part of a binary system with a supermassive star. The fact that the visible star was obviously part of a binary system and the lack of a visible partner led scientists to measure the mass of the invisible partner (calculated from the period of orbital motion) and found it to be greater than the Chandresakar limit, the limit beyond which a star will always form a black hole.

  • Gold (Score:4)

    by flatpack ( 212454 ) on Wednesday September 13, 2000 @09:57PM (#780659)

    They use gold in all of the X-ray mirrors I've heard of - it is a heavy enough atom that the innermost electrons are tightly bound and the energy from X-rays only causes a transition to a higher energy level rather than ionizing it.

    This page [esrin.esa.it] describes the manufacture of an X-ray mirror for an ESA mission. I assume they're all fairly similar.

  • Ahh but... (Score:4)

    by flatpack ( 212454 ) on Wednesday September 13, 2000 @10:30PM (#780660)

    ... black holes also show up in superstring theory (well technically M-theory). You can use a D-brane to model the black hole, and this technique has been used to acheive a first principles calculation of the microscopic entropy of a black hole, whereas traditional techniques used fairly general arguments and a bit of hand-waving.

    On a side note, string theory may suggest ways that information can escape from a black hole due to violations of locality. This is still very much open to debate though.

    For more information, see here [cam.ac.uk] at the Cambridge University's Relativity pages.

  • No, speed of light barrier wasn't broken (Score:5)

    by flatpack ( 212454 ) on Wednesday September 13, 2000 @11:28PM (#780661)

    I don't know how relevant this is, but we just had an article (too lazy to link, sorry) about how the speed of light barrier was broken (by light, ironically). If this is true, doesn't it shoot many physics theories down the drain? And if so, how would if affect this one?

    You mean this article [slashdot.org]? It wasn't really light travelling faster than light at all, merely an effect due to the fact that the pulse of light has a leading edge which travels ahead of it. When this leading edge hit the target, the entire pulse was recreated and transmitted from the other side of the caesium target.

    Whilst it looked like the speed of light barrier was broken, it wasn't really, it was just a cunning effect. Whether this effect could be used to transmit information faster than light is unknown - it depends on whether this leading edge can hold information or not.

    As for tachyons, well they always travel faster than light and indeed speed up as they lose energy - a tachyon with zero energy would travel at infinite speed!

  • Black holes and naked singularities (Score:5)

    by flatpack ( 212454 ) on Thursday September 14, 2000 @02:24AM (#780662)

    When a star collapses the matter begins to implode upon a point, eventually crossing the point where the escape velocity becomes greater than the speed of light and a black hole is formed. The edge of this black hole is what we call the event horizon - anything passing within the event horizon cannot ever escape. The simple solution is described by the Schwartzchild metric.

    The matter however is still collapsing to a point at the centre of the black hole. According to general relativity there is nothing to stop this collapse and we end up with a point of infinite density and zero volume - a singularity.

    However when you come to rotating black holes (described by the Kerr metric) there are differences. The angular momentum of a collapsing star is conserved, and this causes the black hole's event horizon to bulge out along the equitorial plane, much like the Earth has a slight bulge around its equator. Indeed, the central singularity itself forms a torus rather than a point when the black hole is rotating.

    As angular momentum is increased this bulge gets bigger and the polar size of the event horizon shrinks, until eventually you are left without an event horizon at all, but just a torus-shaped singularity, which is said to be "naked".

    Of course, whether a naked singularity can ever exist is an open question. There is something called the "Cosmic Censorship Principle" which states that the laws of physics will never allow a naked singularity to form, but the final answer is "we don't know".

    Also of interest is that since the naked singularity would be in the shape of a torus you could theoretically pass through the centre of the torus and find yourself somewhere completely different, possibly even in another universe!

    For a fairly technical intro to black holes and singularities, see this article [suite101.com] at suite101.

  • From Open Questions in Physics: [ucr.edu]

    5. Do black holes really exist? (It sure seems like it.) Do they really radiate energy and evaporate the way Hawking predicts? If so, what happens when, after a finite amount of time, they radiate completely away? What's left? Do black holes really violate all conservation laws except conservation of energy, momentum, angular momentum and electric charge? What happens to the information contained in an object that falls into a black hole? Is it lost when the black hole evaporates? Does this require a modification of quantum mechanics?

  • they see a green planet with two arms and a tongue sticking out...:p


    öööööööööööööööööööööööööööööööööööö
  • Editors, please read the articles, before you comment. The proposed interferometric telescope is intended only to work in xray frequencies, not visible light, which is the vast majority of what any ordinary nearby star will produce. The article used analogies (poor, because they were not explained) of, successive images of a nearby star, to explain the resolution capability of this device, but made no claims about actually trying to image these nearby stars. You'd want an array of optical telescopes for that.

    Or... maybe a beowulf clus^H^H^H^H^H^H^H^H crap

  • his means you should get an explosion of radiation as the black hole evaporates entirely, leaving a naked singularity behind it...

    ...or a theoretical partical called a Boltzmann, which would be about as small as the Plank area and contain all of the information 'sucked up' by the black hole during its lifetime. Of course, it's a little easier to believe in a naked singularity (sorry Mr. Penrose)...

    ---

  • A large black hole was discovered in Manchester yesterday. Authorities are looking into it.

    (OT) My last interest in Black Holes was that the warping of space-time would be the method of point-to-point space travel. Unfortunately, if I were to synthesize a black hole in my kitchen the radiation would probably kill me. Any practical use for these things, other than fodder for nobel prizes?

    Vote [dragonswest.com] Naked 2000
  • Will they be using this telescope to peer into the neighbor's bedroom and publish the pictures in a magazine...?
  • Remember, /. had an article earlier where physics and General Theory of Relativity were questioned. We don't even know if black holes exist or not, and until physics gets to the point where we can truly prove that Relativity as Einstein theorized is basically unchallenged it could be a waste of money simply to search for black holes.

    However, if the 'scope will be put to good use for more than _just_ black hole chasing it may be fine. I wonder what they would expect to 'see' at an event horizon anyway. I'd assume that it would be well, black, at a fine enough resolution and zoom anyway...
  • Sure, as long as they send me the pictures, hence the email addy...

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