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Space Science

Nearby, Recent Interplanetary Collision Inferred 88

The Bad Astronomer writes about a new discovery by the Spitzer Space Telescope, which detected signs of an interplanetary smashup only 100 light-years from here, and only a few thousand years ago. There's a NASA-produced animation of the collision between a Mercury-sized planet and a moon-sized impactor. The collision's aftermath was detected by the presence of what are essentially glass shards in orbit around the star. Here's NASA's writeup.
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Nearby, Recent Interplanetary Collision Inferred

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  • cocks (Score:-1, Offtopic)

    by Anonymous Coward on Monday August 10, 2009 @08:40PM (#29018259)

    Is GNAA still alive?

  • by olsmeister ( 1488789 ) on Monday August 10, 2009 @08:41PM (#29018263)
    the guy posting the blog states: "the shock wave ring travels around the planet as shown, but when the ring converges on the point opposite the collision point, there would be a huge explosion and a vast plume of material launched into space. No one ever puts that in their animations"

    I thought the same thing when I watched the video - there would be a godawful explosion at the antipode
  • by MichaelSmith ( 789609 ) on Monday August 10, 2009 @08:41PM (#29018265) Homepage Journal
    Google is trying to flog me glass repair and weight loss services.
  • by XPeter ( 1429763 ) * on Monday August 10, 2009 @08:42PM (#29018271) Homepage

    100 light-years! Boy that barely missed us, better put on your hardhats boys because the next mash up is said to be only 80 light-years away!

  • by TheModelEskimo ( 968202 ) on Monday August 10, 2009 @08:53PM (#29018351)
    "Just what are you inferring?" *annoyed look*
  • by gmuslera ( 3436 ) on Monday August 10, 2009 @08:56PM (#29018363) Homepage Journal
    The civilization that was living in that planet is traveling to a little blue planet that was nearby at a modest 100 light years. Invasion is scheduled for next Tuesday.
    • by INeededALogin ( 771371 ) on Monday August 10, 2009 @09:15PM (#29018477) Journal
      The civilization that was living in that planet is traveling to a little blue planet that was nearby at a modest 100 light years. Invasion is scheduled for next Tuesday.

      Little did we know... District 13 was filmed with no computer animations at all.
      • by Pulse_Instance ( 698417 ) on Monday August 10, 2009 @09:31PM (#29018561)

        The civilization that was living in that planet is traveling to a little blue planet that was nearby at a modest 100 light years. Invasion is scheduled for next Tuesday. Little did we know... District 13 was filmed with no computer animations at all.

        Can I borrow the machine they used to travel in time then?

        • by Anonymous Coward on Monday August 10, 2009 @10:05PM (#29018743)

          There's no need for time travel. An FTL drive (time machine) would have allowed them to arrive before the impact was visible here, a "few thousand years ago." Which, thanks to relativity, would mean they'd arrive before it happened.
            Arriving next tuesday means they've got a drive on their generation ship that can hit a little over .1c or so - crossing about one light year every ten years. Impressive, but not a time machine.

          • by __aasqbs9791 ( 1402899 ) on Monday August 10, 2009 @10:11PM (#29018785)

            FTL would only make them think the trip was shorter, not make them go back in time.

          • by thasmudyan ( 460603 ) <thasmudyan@openfu. c o m> on Tuesday August 11, 2009 @06:55AM (#29021367)

            Having an FTL drive doesn't mean it's a time machine. The actual method of travel is important here. It's impractical to go at relativistic speeds that are a considerable fraction of the speed of light, and it's pretty darn impossible to accelerate even beyond 99% of c. Theoretically, going faster than c could mean going back in time, but there is simply no way to accelerate normal matter in this fashion.

            It's very likely any FTL drive technology would have to employ other means, like bending spacetime so the external distance traveled is way bigger than the subjective distance for the spacecraft in question. This could be done with a wormhole-like mechanism for example. Whether or not time flows differently for the travelers (relative to the galactic frame of reference) depends entirely on the details of this technology that we do not yet have access to.

            For example, if I arrive at Alpha Centauri in two minutes from now, and come back to Earth in two more minutes Earth time, that doesn't necessarily mean I have traveled back in time 8 years. It just means there is no way I could have done that as a lump of ordinary matter traversing the entire distance through normal space.

            • Yeah it kinda does. (Score:3, Informative)

              by Chris Burke ( 6130 ) on Tuesday August 11, 2009 @10:38AM (#29023443) Homepage

              Having an FTL drive doesn't mean it's a time machine. The actual method of travel is important here.

              Yes actually FTL does mean you have a time machine, and the method of travel doesn't really matter. It's not like a Back to the Future time where you can arbitrarily go backwards and forwards as far as you want, it's limited to past-only and by how far and fast you can actually travel and how fast your non-superluminal spaceships can travel. But from some observer's reference frame you will have traveled back in time and broken causality by arriving at your destination before you left, simply by moving faster than c relative to them.

              And if you incorporate a second FTL journey, it's actually possible to arrive at your starting point before you left according to all reference frames.

              Here's an explanation [wikipedia.org]. There's a nice explanation with graphs and everything . [theculture.org]

              Note that it does not depend on Lorentz Transformation of the super-luminal traveler/communication. The mechanism isn't important. That observers in normal, relativistic reference frames see you traveling faster than c is what is important. If you can do that, you can go back in time.

              Whether or not time flows differently for the travelers (relative to the galactic frame of reference) depends entirely on the details of this technology that we do not yet have access to.

              Time may pass differently for the travelers relative to some reference frame, but remember there are no privileged reference frames in Relativity. You can break causality if you go FTL relative to any reference frame, and if you aren't traveling FTL with respect to any reference frame, then you can't really be said to be traveling FTL can you?

              • by Chris Burke ( 6130 ) on Tuesday August 11, 2009 @10:41AM (#29023481) Homepage

                Oops, my second link to the page with nice graphs [theculture.org] was hidden in a period. The explanation on that page uses instantaneous communication as its example for clarity and simplicity, but all you really need to do is break out of the light cone and you can potentially break causality with time travel.

              • by thasmudyan ( 460603 ) <thasmudyan@openfu. c o m> on Tuesday August 11, 2009 @10:53AM (#29023633)

                But from some observer's reference frame you will have traveled back in time and broken causality by arriving at your destination before you left, simply by moving faster than c relative to them.

                If that were true, quantum entanglement would break causality. Actually, what we perceive as causality is a symptom, not the cause. Hence it's an illegal assumption that time travel would _have_ to occur every time local effects shift (for lack of a better word) between two points in space faster than it would take a photon to traverse.

                Time may pass differently for the travelers relative to some reference frame, but remember there are no privileged reference frames in Relativity. You can break causality if you go FTL relative to any reference frame, and if you aren't traveling FTL with respect to any reference frame, then you can't really be said to be traveling FTL can you?

                I think most people here, including possibly myself, already know about relativistic effects, there is no need to preach. The whole discussion was _not_ based on the idea of actually accelerating any quantity of matter to causality-breaking, faster-than-light speeds to begin with. There is simply no propulsion system that can do that. What we may be able to build, however, is a system that achieves the same effect by bending spacetime in a very neat way. This is what SciFi nerds call FTL. It's a theoretical system with theoretical properties. But _if_ it works, it's not a time machine simply because it teleports matter between two points "faster" than it would take a ray of light to do so.

                • Absolutely does. (Score:3, Informative)

                  by Chris Burke ( 6130 ) on Tuesday August 11, 2009 @11:59AM (#29024597) Homepage

                  If that were true, quantum entanglement would break causality.

                  Not it wouldn't, because nothing is traveling faster than c in entanglement, not even information. In fact, it is exactly for the reason I'm describing that demonstrates why quantum entanglement can't be used to send information. Nor can any effect resulting from the entanglement being collapsed on the "other end" be distinguishable from it collapsing on your end. There is no possibility of breaking causality.

                  However macroscopic-you traveling FTL most definitely involves transferring mass and information and thus causality can be broken.

                  Actually, what we perceive as causality is a symptom, not the cause. Hence it's an illegal assumption that time travel would _have_ to occur every time local effects shift (for lack of a better word) between two points in space faster than it would take a photon to traverse.

                  Actually, causality is one of the basic assumptions of Relativity. That's how Einstein ended up arriving at the conclusion that nothing can travel faster than light. He assumed causality was inviolate, and he assumed that c was constant for all observers. It was the latter notion that led to the idea that different observers could see things happening at different times. And this led to the notion that if one could travel faster than c, some observer would see effect happen before cause, violating causality.

                  And I didn't say time travel necessarily had to happen in any particular instance of FTL. I said FTL necessarily allows for time travel. Which, if you look, every reference agrees with.

                  I think most people here, including possibly myself, already know about relativistic effects, there is no need to preach. The whole discussion was _not_ based on the idea of actually accelerating any quantity of matter to causality-breaking, faster-than-light speeds to begin with. There is simply no propulsion system that can do that. What we may be able to build, however, is a system that achieves the same effect by bending spacetime in a very neat way. This is what SciFi nerds call FTL. It's a theoretical system with theoretical properties. But _if_ it works, it's not a time machine simply because it teleports matter between two points "faster" than it would take a ray of light to do so.

                  Yes I understand that and I thought I was pretty clear in stating that I was not referring to an object accelerated past c. Any method of travel which appears to be super-luminal to any observer breaks causality. The poster was suggesting a method where some observer would agree that you traveled FTL, yet because you didn't "really" go FTL you get around Einstein's conclusion. That simply isn't true.

                  Energy-wise, accelerating anything to c is impossible. Causality-wise, going faster than c by any method is impossible. I'm a Sci-Fi nerd, and hey it's neat to think about warp driving letting you get FTL without actually having to accelerate to make it seem semi-plausible. Nevertheless, even though it doesn't work that way in Star Trek, warp drive allows time travel.

                  In order for it to really work, we need more than just warp drive. We also need to violate Relativity. Either causality is not inviolate, and time travel is really possible, or some other assumption of Relativity is broken. That's always possible, sure, but in a Relativistic universe, FTL == Time Travel. Seriously, look it up.

                  • by khayman80 ( 824400 ) on Tuesday August 11, 2009 @12:45PM (#29025207) Homepage Journal

                    Causality-wise, going faster than c by any method is impossible.

                    I've already responded to the parent agreeing with most of your position. However, I think this statement goes a little far. FTL travel almost certainly implies time travel, but relativity only makes a preferred frame seemingly unnecessary given current observations. It doesn't rule out a preferred frame altogether.

                    Also, violating causality is a good reason to be suspicious of a phenomenon, but I don't think it deserves the "impossible" label. Grandfather paradoxes are (IMHO) the only reason to doubt the possibility of breaking causality, and the many worlds interpretation of quantum mechanics eliminates these paradoxes.

                    • Re:Absolutely does. (Score:3, Informative)

                      by Chris Burke ( 6130 ) on Tuesday August 11, 2009 @02:32PM (#29026959) Homepage

                      However, I think this statement goes a little far. FTL travel almost certainly implies time travel, but relativity only makes a preferred frame seemingly unnecessary given current observations. It doesn't rule out a preferred frame altogether.

                      Relativity is predicated on the assumption that there is no preferred reference frame. It is because of that assumption that many of the laws of Relativity are required to ensure that it is the case. If there was a preferred reference frame such that the laws of physics only had to apply to it, but causality could be broken elsewhere, then the Theory of Relativity would be very different.

                      Also, violating causality is a good reason to be suspicious of a phenomenon, but I don't think it deserves the "impossible" label.

                      It's impossible in the Relativistic Universe. It is always possible that Relativity is wrong, and that its assumptions are wrong. Hell, Newton was wrong about his basic and seemingly safe assumption that time was the same for all observers (and I hear he was even smart enough to recognize he was making that assumption and write it down). Maybe causality can be broken. The implications for physics would be profound.

                      Things like Warp Drives are ways to get around the limitations of Relativity without it having to be "wrong" in the hypothetical universe. But it doesn't work.

                      Grandfather paradoxes are (IMHO) the only reason to doubt the possibility of breaking causality, and the many worlds interpretation of quantum mechanics eliminates these paradoxes.

                      I'm going to wait until we unify QM and GR before I agree with that. It isn't clear to me at all that having a loop in causality in your spacetime graph would necessarily mean you have a separate outcome from some quantum waveform collapse such that you are in a different universe at the "end" of the loop vs the "beginning". There is nothing in Relativity (obviously) that would require that to be the case, and there wouldn't be a "end" or "beginning" either.

                      I'm also going to wait until we have some reason to actually prefer the many world interpretation over others before I agree with that. Just because it would be convenient for solving time travel paradoxes in a universe where FTL travel is possible doesn't mean its actually true. Seems more likely (as in agrees with current best theory) that time travel (and thus FTL) is simply impossible.

                    • by khayman80 ( 824400 ) on Tuesday August 11, 2009 @03:31PM (#29028099) Homepage Journal

                      If there was a preferred reference frame such that the laws of physics only had to apply to it, but causality could be broken elsewhere, then the Theory of Relativity would be very different.

                      Yes, but like Newtonian mechanics, modern relativity would still be a useful first order approximation. Plus, to the best of my knowledge relativity has only rarely been tested to more than first order effects.

                      I'm also going to wait until we have some reason to actually prefer the many world interpretation over others before I agree with that. Just because it would be convenient for solving time travel paradoxes in a universe where FTL travel is possible doesn't mean its actually true.

                      I agree; at the moment there's no watertight reason to prefer one interpretation over another. But the alternatives are hidden variables (local variables are ruled out by Bell inequality experiments and nonlocal variables would violate relativity), or the literal Copenhagen interpretation. (There are others, but these are the most popular.)

                      The Copenhagen interpretation is almost certainly wrong [lesswrong.com]. (My only correction to his list is that #6 also applies to the No Hair theorem.)

                    • by Chris Burke ( 6130 ) on Tuesday August 11, 2009 @04:17PM (#29029087) Homepage

                      Yes, but like Newtonian mechanics, modern relativity would still be a useful first order approximation. Plus, to the best of my knowledge relativity has only rarely been tested to more than first order effects.

                      Well what I mean is that the Theory of Relativity only looks anything like it does due to the absence of a preferred reference frame. Newton's Laws are only a good approximation because its basic assumption that time is constant is approximately true for normal speeds/masses. It's difficult to see how "There is no preferred reference frame" could be approximately true, but all the conclusions of Relativity stem from that being exactly true. Without that assumption it wouldn't be even approximately like it is now. And it seems too inherent, too good an assumption, to be turned over but still have the theory hold any water at all. Much like the classical Conservation of Energy has survived the transition to GR and QM, I suspect "all reference frames are equal" will continue to hold true.

                      On the other hand, I'll admit I have a hard time imagining what a universe without causality would be like. Much like I'm sure people looking at Einstein's theory had a hard time imagining a universe where time passed at different rates for different people.

                      We have tested Relativity to the extent of our ability to measure. It's extremely well tested. I'm not sure what second order effects your referring to, but if its possible for us to measure them, we have.

                      I agree; at the moment there's no watertight reason to prefer one interpretation over another. But the alternatives are hidden variables (local variables are ruled out by Bell inequality experiments and nonlocal variables would violate relativity), or the literal Copenhagen interpretation. (There are others, but these are the most popular.)

                      We're already violating Relativity by allowing FTL even in theory, so I have no problem with that aspect. :P

                      The Copenhagen interpretation is almost certainly wrong. (My only correction to his list is that #6 also applies to the No Hair theorem.)

                      I've always hated the Copenhagen Interpretation because it always seemed like a scientific argument based on puns.

                • by khayman80 ( 824400 ) on Tuesday August 11, 2009 @12:31PM (#29025031) Homepage Journal

                  But _if_ it works, it's not a time machine simply because it teleports matter between two points "faster" than it would take a ray of light to do so.

                  No, he's actually right [dumbscientist.com]- any FTL drive combined with a mundane conventional drive can be used to travel back in time.

                  If that were true, quantum entanglement would break causality.

                  Entanglement [dumbscientist.com] isn't a causal phenomenon.

      • by mcatrage ( 1274730 ) on Tuesday August 11, 2009 @10:38AM (#29023439)
        District 9 maybe. Unless these are aliens who do parkour which would be cool.
    • by Shakrai ( 717556 ) on Monday August 10, 2009 @09:31PM (#29018559) Journal

      The civilization that was living in that planet is traveling to a little blue planet that was nearby at a modest 100 light years. Invasion is scheduled for next Tuesday.

      Thankfully the invasion was called off when the aliens learned of mankind's secret weapons: lawyers, building permits and environmental impact statements. Said Fleetlord Atvar, "We came here looking to save our race, not to spend the next two hundred years filling out paperwork. We'll find a new home somewhere else, thank you very much."

    • by gijoel ( 628142 ) on Monday August 10, 2009 @09:44PM (#29018643)
      Not the civilization per se. Just the infant son of the leading scientist who tried to warn them of the impact.

      My calculation predict that he'll land somewhere in Kansas.
    • by StickANeedleInMyEye ( 1253490 ) on Monday August 10, 2009 @10:18PM (#29018833)

      The civilization that was living in that planet is traveling to a little blue planet that was nearby at a modest 100 light years. Invasion is scheduled for next Tuesday.

      Actually they landed here ~4 million years ago but accidentally killed the dinosaurs while landing their pyramids.

    • by Anonymous Coward on Monday August 10, 2009 @10:19PM (#29018847)

      Unfortunately the invasion is necessary, as with the male half of their population killed off in the explosion, the large-chested, blue-skinned all-female crew of the colony ship, just awakening from their hibernation, can't take the risk that the natives won't want to mate with them. ...

      Mmm... ...

      Oh, sorry, I drifted off there. Was I saying something?

    • by Alarindris ( 1253418 ) on Monday August 10, 2009 @10:43PM (#29019011)

      Invasion is scheduled for next Tuesday.

      Must be waiting for Microsoft to releasing a patch for their retrocatalytic ion phaser driver.

    • by rrohbeck ( 944847 ) on Tuesday August 11, 2009 @01:28PM (#29025883)

      I loved the comment about Kryptonite and how the author of the original paper asked if anyone has a Kryptonite infrared spectrum so he can check :)

  • Infidels (Score:-1, Flamebait)

    by Anonymous Coward on Monday August 10, 2009 @09:04PM (#29018411)

    There's no such thing as "planets colliding" you infidels. The great FLYING SPAGHETTI MONSTER is just putting the empirical evidence on scientists telescopes to test your faith. And you are all failing Slashdotters.

    Beware. There's only one God.

  • Actually... (Score:3, Funny)

    by RuBLed ( 995686 ) on Monday August 10, 2009 @09:08PM (#29018439)
    That's no moon.
  • by Evil_Ether ( 1200695 ) on Monday August 10, 2009 @09:30PM (#29018553)
    Why have we never seen any sci fi dooms day weapons of the quality?
  • by Brian Gordon ( 987471 ) on Monday August 10, 2009 @10:03PM (#29018735)

    Giant impacts are thought to have stripped Mercury of its outer crust, tipped Uranus on its side and spun Venus backward, to name a few examples

    Is it just me or is that coolest thing ever? Forget massive trains [imageshack.us].. the male mind cannot help but drool at the idea of planets colliding.

    Venus is awesome; I can't even imagine what that would look like. The impactor rapidly accelerating the rock around it while the rock on the other side of the planet crumples and deforms under titanic pressure. Maybe the crust would be rigid enough to accelerate rapidly in big chunks while the big oceans of rock in the mantle churn and slowly come up to speed.. or maybe it would just blast most of the mass spaceward, leaving the planet to be pelted by continent-sized rocks for the next thousand years..

    But undoubtedly Uranus is the coolest collision. Gas giants are already terrifying (imagine falling straight down into the north pole of Jupiter, falling straight into the bullseye of roaring winds and bottomless stormclouds).. but a mass large enough to alter its inclination exploding through the upper atmosphere as a fireball, and slowly ablating as it buries itself deeper into progressively denser gases, and plunging deeper and deeper into the unplumbed depths of unimaginably violent, raging, endless storms, and finally sinking to the crushing depths of the great core furnace.. come on Hollywood, put your obscene special effects budget to use doing something like this.

  • by Anonymous Coward on Monday August 10, 2009 @10:32PM (#29018945)
    There'll be an old guy that dies and a hot girl with a Toughbook that's going to have a really tough few days soon trying to get to JPL...
  • by florescent_beige ( 608235 ) on Monday August 10, 2009 @11:28PM (#29019277) Journal
    That animation reminds me of a job interview I had once...
  • by Anonymous Coward on Monday August 10, 2009 @11:32PM (#29019297)

    Reminds me of a scene from Red Dwarf [youtube.com].

  • by __aajfby9338 ( 725054 ) on Tuesday August 11, 2009 @01:27AM (#29019871)

    TFA wrote:

    And there's another thing that I find personally very cool. Remember, HD 172555 is only 100 light years away. That is extremely close on a galactic scale (our galaxy is 100,000 light years across, so this star is our next door neighbor). It seems incredibly unlikely that this is a rare event in the galaxy, since this happened so close by and so recently.

    That's like saying "somebody living within five miles of me was struck by lightning last week, so it seems incredibly unlikely that being struck by lightning is a rare event on this planet". A single sample says nothing about the probability of the event, other than that it's nonzero.

    • by Anonymous Coward on Tuesday August 11, 2009 @04:08AM (#29020601)

      What I would like to know is, did we see it?
      We have been recording interesting astronomical events for "...the last few thousand years or so." So did it produce enough radiation [in the visible spectrum] to show up here?
      How long do you reckon the spike in radiation lasted for, seconds, minutes, hours, days?

      My wild guess is No [not more energetic that a very cold tiny spot on the surface of its' star] and minutes.

    • by kayditty ( 641006 ) on Wednesday August 12, 2009 @06:58PM (#29045255)

      I've always been dubious about these sorts of claims as well, but I think they know that. it seems like more of a probability statement ABOUT the probability rather than a probability itself. and whether that makes any logical sense, I can't say. tentatively, it seems to.

  • by Anonymous Coward on Tuesday August 11, 2009 @02:16AM (#29020117)

    The timing seem to be perfect for the star of Betlehem mentioned somewhere?

  • by VoidCrow ( 836595 ) on Tuesday August 11, 2009 @06:26AM (#29021221)
    How many stars in a sphere of 100 light years radius from the Sun?
  • by arkarumba ( 763047 ) on Tuesday August 11, 2009 @09:15AM (#29022391) Journal

    ...as if millions of voices suddenly cried out in terror and were suddenly silenced

One man's constant is another man's variable. -- A.J. Perlis

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