Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!

 


Forgot your password?
Close
typodupeerror
×
Space Science

Excursions at the Speed of Light 360

Posted by Zonk from the nice-bike dept.
D4C5CE writes "S/F fans can finally find out what you really get to see at relativistic velocity, and tourists are one step closer to "doing Europe in a day" in these amazing Space Time Travel simulations of the Theoretical Astrophysics & Computational Physics department at the Institute for Astronomy and Astrophysics Tübingen. They put you in a driver's seat that both Armstrong the Astronaut and Armstrong the Cyclist would equally enjoy, in simulators built to ride a bike at the speed of light."
This discussion has been archived. No new comments can be posted.

Excursions at the Speed of Light More

Excursions at the Speed of Light

Comments Filter:

  • Good Further reading.... (Score:3, Interesting)

    by MrByte420 ( 554317 ) * on Sunday May 15, 2005 @07:58PM (#12539270) Journal
    I'm presently ingrossed in Brian Greene's new book called "The Fabric of the Cosmos" and does a wonderful job at creating lively understandable analogies while sticking to alot of interesting science. He covers the history and philospophy of how problems involving realtivity, time, and space have evolved - stronly reccomend it...
    • "I'm presently ingrossed in Brian Greene's new book called "The Fabric of the Cosmos"
      *Spoiler Warning*

      Brian Greene defeats the evil dragon of ignorance at the end, but emphatically, does not get the lady.

  • G forces (Score:2, Interesting)

    by Turn-X Alphonse ( 789240 )
    What about the G forces at the speed of light? Does it just rip peoples skin off?

    • Re:G forces (Score:2, Informative)

      by gandalphthegreen ( 751209 )
      Well, there aren't any G forces at the speed of light. Just getting to it and back down...

    • Re:G forces (Score:5, Informative)

      by 3.1415926535 ( 243140 ) on Sunday May 15, 2005 @08:02PM (#12539288)
      G-force is caused by acceleration. Assuming you accelerate slowly enough, you can get up to $VERY_FAST without dying.

      • Re:G forces (Score:5, Insightful)

        by fm6 ( 162816 ) on Sunday May 15, 2005 @08:11PM (#12539341) Homepage Journal
        It's a little sad that most people still don't understand the difference between speed and acceleration. When I first read about the Scientific Revolution as a kid, the writer spent a lot of time sneering at medieval scholars who stubornly stuck to Aristotle's physics [answers.com] despite all the experimental evidence showing that it was wrong. But as far as most people are concerned (including the script writers on Star Trek) Aristotle has never been debunked.

        • Re:G forces (Score:5, Funny)

          by back_pages ( 600753 ) <back_pages@@@cox...net> on Sunday May 15, 2005 @09:27PM (#12539642) Journal
          It's a little sad that most people still don't understand the difference between speed and acceleration. When I first read about the Scientific Revolution as a kid, the writer spent a lot of time sneering at medieval scholars who stubornly stuck to Aristotle's physics despite all the experimental evidence showing that it was wrong. But as far as most people are concerned (including the script writers on Star Trek) Aristotle has never been debunked.

          Ha, that's easy for a level 7 magic user to say! Some people simply don't have the high INT scores to understand the difference between speed and acceleration. That's why they're so BAD at using a bow and arrow, or even a sling (even level 1 wizards can use a sling hahaa). Anyway, after slaying this sweet dragon last week, I found like a million +2 INT hats. Maybe I should sell them and get rich then everyone would know the difference between acceleration and speed and you wouldn't have a reason to be so sad.

          Btw, that was a hilarious email forward you sent me about "10 ways warriors are dumb". You should add a new one to the list 11) Warriors can't even name five flaws in Aristotle's physics!! haha So is your mom still mad or can we play at your house again on Tuesday?

      • Re:G forces (Score:5, Informative)

        by qmaqdk ( 522323 ) on Sunday May 15, 2005 @09:10PM (#12539576)
        A human being can tolerate up to 5 G (fighter pilots can go to 9 G, but only for short periods of time). That is an acceleration of about 50 m/s^2. If you were able to sustain this acceleration all the way to light speed (which you wouldn't because near light speed the amount of energy needed to accelerate tends to infinity) you would have to keep accelerating for

        300000000/50 = 6000000 seconds, or about 70 days.

        Deceleration would require the same amount of time. So the Tübingen experience would be a 140-day-not-very-pleasent-5-G bike ride :)

        • Re:G forces (Score:2, Informative)

          by rubycodez ( 864176 )
          it's a funny thing, what happens is that you can accelerate subjectively at 5G or whatever rate you want indefinitely, and you'll never reach lightspeed. An outside observer would see your rate of acceleration decrease as you approach the speed of light, such that you never reach the speed of light.

        • Relativistic G forces (Score:5, Informative)

          by Anonymous Coward on Sunday May 15, 2005 @11:16PM (#12540095)
          That's Newtonian. The relativistic acceleration equations are different. See this FAQ [ucr.edu] for the correct equations, which will tell you how long (in either proper or inertial time) it would take to reach a given speed, as measured by an inertial observer initially at rest with respect to the body -- with some calculations for 1 g acceleration.

          (For instance, to reach 0.77c requires 1 year of subjective time or 1.19 years of objective time; for 0.97c, it's 2 years subjective, 3.75 years objective; for 0.99999999996c it's 12 years subjective, 113,243 years objective.)
      • Unless of course you have the misfortune of travelling the speed of light in an atmosphere. The G forces may not rip any skin off, but I bet air would singe it pretty damn well.

    • Re:G forces (Score:4, Informative)

      by Anonymous Coward on Sunday May 15, 2005 @08:06PM (#12539311)
      G force is dependent on acceleration, not velocity. If one were to be accelerated too quickly to the speed of light, you would likely not survive. But if one were to accelerate to the speed of light under livable circumstances, it would not rip your skin off. Once traveling at the speed of light, you will feel just like you feel when traveling in an airplane

    • Re:G forces (Score:5, Funny)

      by Jozer99 ( 693146 ) on Sunday May 15, 2005 @08:34PM (#12539438)
      Thats one long block! The movie is 3 or 4 seconds long, so that is a 1,200,000 km street block.

  • The nerds have already seen (Score:5, Informative)

    by kernel_dan ( 850552 ) <slashdevslashtty AT gmail DOT com> on Sunday May 15, 2005 @08:08PM (#12539326)
    Lightspeed [sourceforge.net] is a simulator for velocities at c and below. Screenshots [sourceforge.net] are available.
  • I wonder what a website (and associated server/network tin) looks like when it's Slashdotted at the speed of light?

  • What? (Score:3, Funny)

    by Devar ( 312672 ) on Sunday May 15, 2005 @08:10PM (#12539335) Homepage Journal
    Reduce the speed of light to 30 kilometres per hour! Then you too can ride at the speed of light!! Easier if you have a motor bike.

  • This has been done before (Score:5, Informative)

    by krumpet ( 29617 ) on Sunday May 15, 2005 @08:12PM (#12539344) Homepage
    I have seem something similar to this before. Check out:

    http://www.anu.edu.au/Physics/Searle/ [anu.edu.au]

    and

    http://www.anu.edu.au/Physics/Savage/TEE/ [anu.edu.au]

    • Even earlier... (Score:3, Informative)

      by ktakki ( 64573 )
      I recall seeing still shots of a speed-of-light visualization in a brochure from Carnegie-Mellon's supercomputing center, back in the early '90s.

      I can't find the brochure online (this was pre-WWW), but I think the stills came from this paper [acm.org], from 1990.

      Not that I think that this sort of thing is redundant. As technology advances, this is the type of visualization that's worth repeating on new hardware and new software.

      k.

  • No way. (Score:4, Funny)

    by diesel66 ( 254283 ) on Sunday May 15, 2005 @08:14PM (#12539361)
    Look, I've been through Tübingen at the speed of light, and it doesn't look anything like that!

  • Length contraction? (Score:2, Interesting)

    by Futonchild ( 875487 )
    I always understood that distances lying on lines parallel to your path (e.g. the length of a passing storefront) got shorter as you approached c. In the video it looks like the storefronts remain a constant length, or maybe even expand, as the speed increases. Am I missing something?
    • They're simulating the *visual* effect which is much different than just the Lorentz transformation because of the differing light travel times from various parts of the object to your eyes. For example, a body actually appears *rotated* instead of just Lorentz contracted.

  • How long? (Score:3, Insightful)

    by OverflowingBitBucket ( 464177 ) on Sunday May 15, 2005 @08:30PM (#12539425) Homepage Journal
    Those curved buildings are kinda cool, but how long would those buildings even be in your field of vision if you were blasting past them at the speed of light? I don't think your brain would get a chance to process that kind of detail before it blurred into the image from the next microsecond, which would probably be completely different. I'd say it'd all be a messy blur.

    Looking backwards would be kinda sweet though, if it didn't blind you immediately.

    • Re:How long? (Score:3, Insightful)

      by mnmn ( 145599 )
      Blind you? The photons rate entering your eyes looking backward would be much less, so it'll be pretty dark. You wouldnt feel a thing if the velocity is constant.

      Looking forward.. now thats a different story.
      • Blind you? The photons rate entering your eyes looking backward would be much less, so it'll be pretty dark. You wouldnt feel a thing if the velocity is constant.

        Looking forward.. now thats a different story.

        I was thinking at near but below light-speed, basically a very large number of sources in the distance having their light reach you all at roughly the same time. Like a sonic boom, but with light. In the last couple of minutes I've swung from agreeing with you to disagreeing, and retyped this comment

      • Re:How long? (Score:3, Insightful)

        by Phleg ( 523632 )
        Actually, light travels towards and away from you at light speed, no matter your speed. So the number of photons entering your pupils would be exactly the same.
        • Would it?
          Imagine travelling from Earth to Alpha Centauri at .99c. It would take about 4 years, Earth time, and .57 years, your time. At .01c, it would take about 400 years Earth time and 400 years your time.
          In this second case you would be shading the Earth for 400 years, so you are absorbing the photons that the Earth would absorb for the next 400 (or so) years during the course of 400 of your years (assuming the photons coming parallel, but whatever).
          In the first case you would be shading the earth for 4
      • I'm pretty sure you've just thoroughly confused relativity with Newtonian mechanics, but I don't have a strong enough grasp on relativity myself to give you a good reason why.

        Perhaps someone else can.

        p

    • Re:How long? (Score:4, Funny)

      by StikyPad ( 445176 ) on Sunday May 15, 2005 @10:56PM (#12540017) Homepage
      Those curved buildings are kinda cool, but how long would those buildings even be in your field of vision if you were blasting past them at the speed of light?

      First of all, it's near lightspeed.

      More importantly, they simulated light moving at 30km/h rather than 300km/s. Fortunately this had no effect on the real speed of light, so you're free to continue driving at highway speeds. Good thing too, because it would add a whole new dimension to traffic violations.

      "Your honor, I literally couldn't see him until after we collided."

      "$500 fine for exceeding the speed of light."

      "Your honor, I didn't realize.. I thought I was just drunk!"

  • oblig. Red Dwarf! (Score:5, Funny)

    by Johnny Mnobflaps ( 662730 ) on Sunday May 15, 2005 @08:32PM (#12539431)
    HOLLY: Look, we're travelling faster than the speed of light. That means, by the time we see something, we've already passed through it. Even with an IQ of 6000, it's still brown trousers time.

    or maybe that's brown bike shorts.

    eww.

    • But that quote doesn't make sense. Sure, you theoretically would not be able to see something until you've passed it, but that's ignoring the fact that the light has already been emitted. If anything, you would see exactly the same as if you were standing still - negating brain activity of course. Think about it, what you are seeing on your screen is what happened a few picoseconds ago - if you move closer to it, you're seeing things sooner, and you saw the update faster while you moved closer, but you won'
  • I've heard that when you're travelling near lightspeed, things behind you (say, 120 degrees from the forward direction) appear to be in front of you. Can anyone give the Relativity for Dummies version of why this happens?
    • It's in the this explanation [spacetimetravel.org]. There's a diagram at the bottom which explains it much better than I can in words.

    • Re:Anyone got an idea what's going on here? (Score:4, Interesting)

      by mnmn ( 145599 ) on Sunday May 15, 2005 @08:53PM (#12539505) Homepage
      Sure.

      See light travels at the speed of light. You cant travel faster, or even AT the speed of light.

      But if youre zipping by an object that emits light, and its light doesnt travel in the same direction as you, its speed component in that direction is also slower than the speed of light, and you can catch up and see the object after you're past it.

      Lets try that again.

      Imagine youre on a bike, zipping past a lamppost. The light the lamppost emits travels in all directions. Now take the photos that are emitted in the same direction youre going, at the same time that youre just crossing the lamppost... now youre travelling parallel to that photon, although it beats you in speed.

      However, if the lamppost was say 10m away from you when you zipped past, the photon you'd see is the photon the lamp emits not in the same direction youre travelling, but slightly towards you. If youre travelling north, the photon is travelling northwest, towards you. After youve crossed the lamppost, some distance later, the photon reaches you, because it had to travel a bigger distance, going in your travel direction (north) as well as towards you (west), and we all know the hypotenuse is longer than the base or height.If you travelled faster than the photon's north speed component, you'll see greater than 180 degrees around you... but never 360.
      • Thank you so very much. This part of near-light-speed motion has always eluded me. Thanks to your mental image, I am finally able to understand this. And I think I'll be able to explain it to others, as well.

        (Although I'm sure it helps that I'm well past tipsy as I type this.)

  • I Have Seen This (Score:3, Funny)

    by ArchAngel21x ( 678202 ) on Sunday May 15, 2005 @08:39PM (#12539458)
    This is what I see when I sprint to an all you can eat buffet after someone else has offered to pay. I have been called many things, but late for dinner is not one of them.

  • Light speed? (Score:4, Funny)

    by dj245 ( 732906 ) on Sunday May 15, 2005 @08:42PM (#12539464)
    I prefer Ludicrous speed [boxofficeprophets.com]!
  • Wouldn't the blueshift when traveling at such speeds push everything out the visible spectrum? So you wouldn't actually see anything, you'd just get a nasty dose of Gamma waves... or worse?
    • At forward viewing angles, yes, the images would be blue-shifted, but this doesn't mean everything goes dark. Visible becomes UV, and infrared becomes visible. But this is angle-dependent. Light arriving from behind you is actually red-shifted.

      And yes, pushing several hundred watts per square meter of visible light into the UV range would result in a terrible sunburn.

  • Traffic Lights.. (Score:2, Insightful)

    by medgooroo ( 884060 )
    if, ignoring science and all that hoohah stuff, you could ride a bike at the speed of light around the place, would there be any need for traffic regulation or do collisions just become so hideously unlikely that it doesnt matter? /ot

  • Tubingen? (Score:4, Funny)

    by MrAndrews ( 456547 ) <mcm&1889,ca> on Sunday May 15, 2005 @08:47PM (#12539482) Homepage
    I showed my wife the videos cause they were cool, but she got all misty-eyed about seeing Tubingen again, so I'm in for a long night of hearing about how much fun she had at university there. Sigh. Why can't more people appreciate the value of astrophysics for astrophysics' sake?

  • No blueshift (Score:5, Interesting)

    by Vilim ( 615798 ) <ryan@jabber[ ]k.ca ['woc' in gap]> on Sunday May 15, 2005 @08:53PM (#12539506) Homepage

    They are missing the blueshift you would encounter at that speed. However I guess they couldn't be accurate because wouldn't the frequency would shift to far above the ultraviolet quite quickly?

    • However I guess they couldn't be accurate because wouldn't the frequency would shift to far above the ultraviolet quite quickly?

      Yep--although that could be pretty cool, too. If we set aside the rapid blinding due to exposure to intense ultraviolet (and x-rays, and gammas, as you get to higher velocities) the view would be very interesting. The visible light portion of the spectrum would still be just fine off to the sides. There would be a ring of "normal" view perpendicular to the direction of your mo

  • Mr. Tompkins in Wonderland (Score:4, Informative)

    by dpbsmith ( 263124 ) on Sunday May 15, 2005 @09:01PM (#12539537) Homepage
    There should, I think, have been at least a nod given to George Gamow whose 1947 book, "Mr. Tompkins in Wonderland," attempted to explain relativity and quantum mechanics by putting Mr. Tompkins into situations like this. If I remember correctly, one of the episodes literally did involve his riding a bicycle in a Wonderland in which c was something like twenty miles an hour.

  • But, but.. (Score:5, Funny)

    by xchino ( 591175 ) on Sunday May 15, 2005 @09:07PM (#12539556)
    "They put you in a driver's seat that both Armstrong the Astronaut and Armstrong the Cyclist would equally enjoy"

    But what about Armstrong the overly stretchy action figure?
    • But what about Armstrong the overly stretchy action figure?

      In Stretch Armstrong's frame of reference, it's everyone else who's stretching madly!

  • OK, read the article.

    The Through the city at the speed of light [spacetimetravel.org] demo is all very lens-effect-y, but there's no account of colour-shift. As you get faster the approaching wavelengths will shorten (Blue Shift) until you get fast enough that all (normally) visible light shifts up and out of our acuity.

    Everything you'd see would be sub-infrared shifted into your spectrum, and this doesn't seem to take that into account.

  • It keeps referring to the "speed of light" which itself is not constant -- is a function of the media it travels in.
    --
    All your speed is belongs to us.
    • They're referring to c, the speed of light in a vacuum.

      Otherwise, it's a bit bulky to say "E=m(something which is a dependent of the medium it travels in)^2".

      Of course, put light into a Bose-Einstein Condensate, and you could cycle faster than it...

    • Speed of light IS a constant. (Score:4, Informative)

      by Spaceman40 ( 565797 ) <blinks&acm,org> on Monday May 16, 2005 @12:21AM (#12540412) Homepage Journal
      What you're talking about (the slowing down of light in glass, etc.) is the effect of light hitting a molecule of something, being absorbed by it, and then being reemitted out the other end.

      Light's speed is a constant, c. It's the speed of absorbtion and reemission that changes it's apparent speed through substances.

      • Not quite (Score:3, Informative)

        by Jamie Lokier ( 104820 )

        Normally we use the words absorbtion and re-emission to refer to electron energy-level transitions within the molecule: photons are absorbed and promote electrons to higher energy levels; then, at a somewhat random time and in a somewhat random direction (not uniformly), electrons drop to lower energy levels and re-emit photons. (Note that these transitions aren't instantaneous, nor entirely well defined in time, but we call them quantum events anyway).

        A notable effect of complete absorbtion and re-emiss

  • Cosmos (Score:5, Informative)

    by dexter riley ( 556126 ) on Sunday May 15, 2005 @11:19PM (#12540106)
    C'mon, surely someone else remembers the episode of Carl Sagan's series "Cosmos" where they did the relativistic motor scooter trick? In a small town in Italy, where the speed of light is only 40 km/hr (strictly enforced!) a young man leaves on a tour of the city at relativistic speeds, leaving his friend and younger brother behind. Sagan describes the effects of blue- and red-shifting, the contraction of the cyclist's length, and the dilation of time. It ends with the young man returning to the place he started, just a few minutes (in his frame of reference) after he left. Sadly, he finds all his friends gone, and only his once-younger brother, now an old man, still waiting for him.

    I don't know why, but the bittersweet reunion of the two brothers, as well as the story of the late Wolf Vishniac in the "Blues for a Red Planet" episode, both make me cry.

    • Re:Cosmos (Score:3, Insightful)

      by d474 ( 695126 )
      Carl Sagan always had a way blending the cold of science with the warmth of humanity. It's always easier to "get it" with science if you allow the implications sink into your emotions. That's where the meaning comes from.

  • I installed it, and it works! (Score:3, Funny)

    by tod_miller ( 792541 ) on Monday May 16, 2005 @01:55AM (#12540817) Journal
    I looked at the front page, and I saw an article about OSS Java, that was posted a week ago!!!

    Wow!! the effects of time/spped of light being made clear!

    Now I don't need to subscribe the /., I can read stories before they are even submitted!

Slashdot Top Deals

"Everyone's head is a cheap movie show." -- Jeff G. Bone

Close