If the speed of light is equal to "c" and you are traveling in the same direction as the beam of light at speed "x" then shouldn't the speed of light you're observing be equal to "c-x"? I know it's not and that "c" is constant regardles of the speed of the observer but why?
2006-09-26 14:06:45 · 5 answers · asked by rubenff2000 1 in Science & Mathematics ➔ Physics
The strict addition/subtraction of speed in this manner is valid only for low speed; that is Newtonian physics. Relativity has the speed of light a constant no matter where you are and what you do. How to reconcile those? Well, speed is a distance traveled in a given amount of time. If the speed is a constant, then the other factors will change. If you travel at a high velocity, time gets slower, and you are shrunk. For you who is traveling, it is the rest of the universe that is shrinking and with slower time.
The one constant: everyone agree that the speed of light in a vacuum is the same.
2006-09-26 14:19:20 · answer #1 · answered by Vincent G 7 · 1⤊ 0⤋
I took a class in e-mag back in college. I forget the exact setup, but one day the prof is going over the propogation of an electromagnetic wave using simple laws of e-mag. So, if you go for the ideas about electricity and magnetism, it turns out you can mathematically deduce from those laws that the speed of the wave is constant. There was something in the math that showed it didn't matter what frame you started from because the initial equations didn't use them.
I wish I could remember more...but it had to do with the speed of a light wave based on the two fields.
2006-09-26 21:15:20 · answer #2 · answered by sideshot72 3 · 0⤊ 0⤋
The speed of light in vacuum is the same for all observers in inertial reference frames, because relativistic effects actually distort physical objects and the passage of time in such a way that c will always be measured at the same value.
It is definitely counter-intuitive, because we live in a relatively low-energy world where we never experience noticeable relativistic effects; this means our "common sense" expectations of reality are incomplete. They do correspond well with Newtonian physics, but when you start dealing with speeds of 10% of c or greater, the Lorentz-Fitzgerald distortion becomes significant and reality does not match up with the simple Newtonian model.
This is not to say that relativity is a baseless theory; its predictions have been confirmed countless times and it is truly a reliable basis for predicting scenarios with much higher accuracy than Newtonian physics. At the same time there is something to be said for Newtonian physics; the math is much simpler and as long as you are keeping speeds to a reasonable level you can get very accurate results. NASA uses Newtonian physics to calculate orbital trajectories all the time; this is not a problem because they expect a certain degree of "slop" and error in the rockets themselves and they allow for course corrections as standard operating procedure. The error from Einsteinian vs. Newtonian physics is negligible compared to the error from real-world machinery's imperfections.
2006-09-26 21:46:27 · answer #3 · answered by poorcocoboiboi 6 · 0⤊ 0⤋
it is called perspective
an observer would see that the light would come faster than the speed if it shines at him
however, nothing can go at the speed of light and the speed remains constant
you need an infinite amount of energy to go that fast
2006-09-26 21:14:59 · answer #4 · answered by Anonymous · 0⤊ 0⤋
think about it this way, if you are driving down the road at 60mph and see a car pass you going 65mph, the relative speed is 5mph, but the other car's speed is still 65mph, no matter how fast you travel. So the speed of light remains constant, relative speed can change.
2006-09-26 21:15:43 · answer #5 · answered by Keith H 3 · 0⤊ 2⤋