StreetScooby 5 #1 July 1, 2008 A train is going the speed of light. It turns it's headlights on. A person is waiting on the platform where the train is going. Does that person see the headlights first?We are all engines of karma Quote Share this post Link to post Share on other sites
Butters 0 #2 July 1, 2008 No"That looks dangerous." Leopold Stotch Quote Share this post Link to post Share on other sites
Remster 30 #3 July 1, 2008 QuoteA train is going the speed of light. Thats your problem, right there. If I remember correctly... It can _approach_ the speed of light, but since it has a mass, it cannot go at that speed.Remster Quote Share this post Link to post Share on other sites
ryoder 1,590 #4 July 1, 2008 Quote Quote A train is going the speed of light. Thats your problem, right there. If I remember correctly... It can _approach_ the speed of light, but since it has a mass, it cannot go at that speed. Sure it can! It just needs infinite energy!"There are only three things of value: younger women, faster airplanes, and bigger crocodiles" - Arthur Jones. Quote Share this post Link to post Share on other sites
rehmwa 2 #5 July 1, 2008 QuoteQuoteA train is going the speed of light. Thats your problem, right there. If I remember correctly... It can _approach_ the speed of light, but since it has a mass, it cannot go at that speed. even better, take the observer and assume they have zero mass, then fly them at the train at the speed of light. Then, fix the reference on the observer and then measure the train's speed in those coordinates. now the train is going C. problem solved. ... Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants Quote Share this post Link to post Share on other sites
StreetScooby 5 #6 July 1, 2008 Quote Thats your problem, right there I thought my problems were more difficult to pronounce than that We are all engines of karma Quote Share this post Link to post Share on other sites
billvon 3,110 #7 July 1, 2008 >Does that person see the headlights first? Nope. But that situation's not possible anyway. Better case - a train is going very near the speed of light. It turns its headlights on. Does the person on the platform see the light? Trick question. Literally no; the light will be so far blue-shifted it will be well into the ultraviolet. Heck, it might kill him since it will be getting pretty close to X-rays. However, the photons will arrive before the train. Quote Share this post Link to post Share on other sites
jcd11235 0 #8 July 1, 2008 You've presented an undefined problem. The train would not be observed because it would "appear" to have a length of zero. The light from the headlight would have a wavelength of zero. It's why the speed of light is considered a natural barrier that cannot be crossed. If the train is not actually traveling the speed of light, just very close to it, such as v=0.999…98 * c, then the light would be observed first, although its wavelength would be much too short to be perceived by the naked eye of a human. Of course, so would the light reflecting off the train.Math tutoring available. Only $6! per hour! First lesson: Factorials! Quote Share this post Link to post Share on other sites
lawrocket 3 #9 July 1, 2008 No. The observer will see the light and the train at the same time, is my understanding. However, a person riding on that train will see the light going at light speed relative to the train. Still, however, let's assume that the train cannot go light speed. The train turns on the light. I think the observer will see the light slowly outracing the train. That's my understanding - from having never took a physics class. My wife is hotter than your wife. Quote Share this post Link to post Share on other sites
FreeflyChile 0 #10 July 1, 2008 Even assuming that you could see the light emitted by the train, I don't think the human eye or brain can process the information fast enough for you to see it. Quote Share this post Link to post Share on other sites
jcd11235 0 #11 July 1, 2008 QuoteEven assuming that you could see the light emitted by the train, I don't think the human eye or brain can process the information fast enough for you to see it. Everything you see is a result of photons traveling at (actually very near, since we don't live in a vacuum) c, aka the speed of light.Math tutoring available. Only $6! per hour! First lesson: Factorials! Quote Share this post Link to post Share on other sites
FreeflyChile 0 #12 July 1, 2008 Right, but what I meant is that it'd be happening too fast for you to be able to tell what's going on. Quote Share this post Link to post Share on other sites
jcd11235 0 #13 July 1, 2008 QuoteRight, but what I meant is that it'd be happening too fast for you to be able to tell what's going on. Okay, I think I understand. You mean in the same sense that a bullet could pass in front of your eyes and you would be unlikely to see it.Math tutoring available. Only $6! per hour! First lesson: Factorials! Quote Share this post Link to post Share on other sites
Andy9o8 2 #15 July 1, 2008 You're all hopelessly trapped in the past. Pity, really. http://www.sfu.ca/~adebened/funstuff/warpdrive.html Quote Share this post Link to post Share on other sites
StreetScooby 5 #16 July 1, 2008 Quote Trick question. Literally no; the light will be so far blue-shifted it will be well into the ultraviolet. Heck, it might kill him since it will be getting pretty close to X-rays. However, the photons will arrive before the train. Thanks. So, basically, it's the Doppler effect with photons, is what I'm reading.We are all engines of karma Quote Share this post Link to post Share on other sites
StreetScooby 5 #17 July 1, 2008 Quote Of course, so would the light reflecting off the train. That was going to be the next question... We are all engines of karma Quote Share this post Link to post Share on other sites
StreetScooby 5 #18 July 1, 2008 Quote You're all hopelessly trapped in the past. Have you ever seen Jack Jeffries track? We are all engines of karma Quote Share this post Link to post Share on other sites
skydiver30960 0 #19 July 1, 2008 A hearty "well done" to whoever can name the movie: QuoteGeorge? You know I was wondering,like, like, if you were traveling through outerspace. I mean like you are going real fast, like the speed of light, you know whoooo whoooo and all of a sudden you start screaming, aaaaah, aaaaaah, do you think your brain would blow up? I tried like hell to find it on youtube but the only thing I found was some guy lipsynching to the soundbite while wearing a paper mask. A far cry from the original. Elvisio "glad to be able to contribute to the discussion in a meaninful fashion" Rodriguez Quote Share this post Link to post Share on other sites
jcd11235 0 #20 July 1, 2008 QuoteSo, basically, it's the Doppler effect with photons, is what I'm reading. Yes. Or, thought of in a slightly different way, the Doppler effect with light waves.Math tutoring available. Only $6! per hour! First lesson: Factorials! Quote Share this post Link to post Share on other sites
Gawain 0 #21 July 2, 2008 Quote Quote Quote A train is going the speed of light. Thats your problem, right there. If I remember correctly... It can _approach_ the speed of light, but since it has a mass, it cannot go at that speed. Sure it can! It just needs infinite energy! 1.21 giga-watts is all that's needed... ...that, and an AN-2... So I try and I scream and I beg and I sigh Just to prove I'm alive, and it's alright 'Cause tonight there's a way I'll make light of my treacherous life Make light! Quote Share this post Link to post Share on other sites
StreetScooby 5 #22 July 2, 2008 Quote and an AN-2... Yes,... that's the practical side of physics they don't teach in school We are all engines of karma Quote Share this post Link to post Share on other sites
kallend 2,146 #23 July 2, 2008 Quote Quote and an AN-2... Yes,... that's the practical side of physics they don't teach in school What makes you think that?... The only sure way to survive a canopy collision is not to have one. Quote Share this post Link to post Share on other sites
TankBuster 0 #24 July 2, 2008 UHF Weird Al Guns don't kill people I do.The forecast is mostly sunny with occasional beer. Quote Share this post Link to post Share on other sites
bjjman 0 #25 July 2, 2008 Quote 1.21 giga-watts is all that's needed I thought it was 1.21 jigawatts, whatever a "jigawatt" is. "Great spirits have always encountered violent opposition from mediocre minds." -Albert Einstein Quote Share this post Link to post Share on other sites
