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Natural Science Forum / Physics / Relativity / January 2006IF possible, traveling at speed of light then shine light forward, will is shine?
picture this.... if it were possible that you could travel at the speed of light in a vehicle and you had a light scorce that you were shinning foward as you were going at the speed of light, would the light shine or just be gas? or what do you think? John http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/headlights.html -- Ben > picture this.... if it were possible that you could travel at the speed > of light in a vehicle and you had a light scorce that you were shinning > foward as you were going at the speed of light, would the light shine > or just be gas? or what do you think? > > John Dear extremetech2: > picture this.... if it were possible that you > could travel at the speed of light in a vehicle You can't. So imagine you are travelling impossibly close to c... say a week of your time to cross the Milky Way... http://www.fourmilab.ch/documents/ohmygodpart.html > and you had a light scorce that you were shinning > foward as you were going at the speed of light, > would the light shine or just be gas? or what do > you think? I think you'd be dead, since any particles you'd encounter would make you and your flashlight highly radioactive. Ben Rudiak-Gould pointed you to the right place for a discussion of the topic. David A. Smith yeah it makes sense now, thanks again John Lets say its a flash light traveling at 99.999999999 of 'c' This light coming at an observer would be seen blue,and it hits his eyes with a speed of 186,242 mps. There is no frame of reference that can be used to change light speed. TreBert Dear G=EMC^2 Glazier: > Lets say its a flash light traveling at 99.999999999 > of 'c' This light coming at an observer would be > seen blue,and it hits his eyes with a speed of > 186,242 mps. "Blue" is an understatement. It would be so blueshifted that you could take x-rays with it! If you hurried... > There is no frame of reference that can be used > to change light speed. TreBert Add the word "locally" to the end of that last sentence... and of course this would be in a vacuum. David A. Smith > Dear G=EMC^2 Glazier: > [quoted text clipped - 11 lines] > Add the word "locally" to the end of that last sentence... and of course > this would be in a vacuum. when it hits his eyes it would be locally ,is'nt it? > David A. Smith Dear Mdmeenken: >> Dear G=EMC^2 Glazier: ... >>> There is no frame of reference that can be used >>> to change light speed. TreBert [quoted text clipped - 4 lines] > > when it hits his eyes it would be locally ,is'nt it? A "frame of reference" can be arbitrarily large. Of course such a frame would only be valid in a spacetime with no curvature, and without curvature the speed of light appears to be c over any path. David A. Smith David Have two flash lights back to back both shining in opposite directions,and still SR says they are not traveling twice the speed of light.relative to each other. This is the tricky part,but again there is no frame of reference to show light traveling faster than "c" Light does not use the same physics like a gun firing a bullet TreBert > David Have two flash lights back to back both shining in opposite > directions,and still SR says they are not traveling twice the speed of > light.relative to each other. SR says that the ends of the two light beams are receding from each other at 2c in the flashlight frame. There is no "light beam rest frame", so "relative to each other" is not meaningful in SR. - Randy David I see light never changing its speed. Good reason why light takes 100,000 years to come out of the Sun's core,and break through its surface. Near absolute zero sodium has light slowed to 3mph Best to use the Sun theory here,for it makes more sense. If light did slow down in say water glass,and air than this begs the question. What makes it speed up again? Takes energy to create acceleration. Next question would be why does it stop accelerating once it reaches 186,242 mps TreBert >picture this.... if it were possible that you could travel at the speed >of light in a vehicle and you had a light scorce that you were shinning >foward as you were going at the speed of light, would the light shine >or just be gas? or what do you think? Speed must be specified relative to another object. Your question has no meaning nor have any of the replies. No matter how one accelerates, nothing changes to oneself. The light from one's flashlight will always move forward at c wrt the flashlight. It is impossible to accelerate sufficiently to catch any of the emitted light. There is possibly a theoretical limit to spaceship acceleration involving mc^2.. .The practical problem is to find an engine that will provide plenty of thrust for long periods. Wilson's Third Law states that: If the intrinsic energy (mc^2) of every atom in the spaceship could be used to accelerate the last atom, the total KE of all the expellent would equal Mc^2 (in the frame of the starting point). The latest Pluto probe will end up at about 0.0001c wrt Earth. >John HW. www.users.bigpond.com/hewn/index.htm |
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