isnt it just as reasonable to say that the observer is traveling at c and that light is at rest? isnt this also supported by observing that time slows (perhaps to a stop) are c is approached? isnt time a way of measuring movement? we also know that no observer can truely be at rest so isnt it more logical to say light is at rest and the observer moves at c?
i assume i am wrong but please explain why.
2006-11-28 06:54:53 · 10 answers · asked by karl k 6 in Science & Mathematics ➔ Physics
Lot of confused answers here, including a totally incorrect mention of general relativity (the principle of equivalence is the basis of GR).
ALL motion is realtive. You cannot choose one observer as special over another. So when you fly to London it is as true to say London is coming to you as you are going to London. Both Galileo and Newton knew this, and it is called the principle of relativity.
However, what was observed at the start of the 20C is that ALL observers measure the same result for the speed of light. This is not at all expected intuitively. What you would expect is that if I am moving away from you at a million mph, then if i shine a light away from you the light moves away from me at the speed of light and from you at a million mph plus the speed of light. In fact, it moves away from both of us at the speed of light.
So some assumption we made is wrong. And the assumption that is wrong is simultaneity. You assume that events that are simultaneous for you - say you switching on two lights 100 m apart - are simultaneous for me. In fact, if I am moving past you I will not agree that the events are simultaneous, and this disagreement accounts for us both measuring the same result for the speed of light.
2006-11-28 07:22:03 · answer #1 · answered by Anonymous · 1⤊ 0⤋
Objects that have rest mass, such as yourself, have a range of possible speeds, from zero to just under the speed of light. Any observer is such an object. The relative velocity between two observers is always less than the speed of light. The relative velocity between any observer and a pulse of light is always the speed of light. The mathematics of the Lorentz transform assures that this is so.
As you point out, if you just have one observer and one pulse of light, how can you tell which is moving?
As soon as you have two observers, however, the situation changes. The two observers, both of whom have rest mass, may be moving with respect to each other. In such a situation, the only possible way that both observers can see the light pulse travelling at the speed of light is if both observers are travelling less than the speed of light. The situation is no longer symmetric.
Given enough massive objects around, it is possible to define a standard of rest. This is Mach's principle, and it may not be true although Einstein believed it.
2006-11-28 07:21:23 · answer #2 · answered by cosmo 7 · 0⤊ 0⤋
not at all light speed in a vacuum is a constant but the observers perception of it will change based on his speed
you are getting a bit tangled up with conflicting statements - the fact is that if you travel at light speed and turn on the headlights the light will go nowhere ( sorry couldn't resist )
time 'measures' the order of events not motion ( once again mixing different things )
we measure the speed of distant galaxies through 'red shift' the fact that they are in motion makes the apparent speed of their light seem slower than normal hence the shift toward the red end of the spectrum
since we can measure light moving away and at the same time coming towards us then THAT proves that we are the static component in the measurement ( even in motion as all things are it is only the point you choose that determines motion but speed is determined on a relative to the observer scale ) and yes it is confusing in English that is why they use MATH
2006-11-28 06:57:48 · answer #3 · answered by Anonymous · 0⤊ 1⤋
Hi. The short answer is that all you mention ties into relativity. Time is not a dimension at 'c'. That's why photons do not age. Ever. The view from a photon would be pretty unusual. It forms and then instantly interacts with matter, even if light years have been traveled. Strange.
2006-11-28 07:04:34 · answer #4 · answered by Cirric 7 · 0⤊ 0⤋
Your original question is inherently wrong. The speed of light is constant. An observer's speed is variable. For any constant C minus a variable x to equal any other constant then both C and x must vary. This is impossible because C is always constant.
2006-11-28 07:03:48 · answer #5 · answered by Lucan 3 · 0⤊ 1⤋
The speed of light is constant for ALL observers.
2006-11-28 09:21:20 · answer #6 · answered by Where the 'morrow lives 2 · 0⤊ 0⤋
You are not wrong. What you're describing is the very basis of Einstien's Theory of General Relativity.
It does, however, lead to some astounding consequences. Consider "The Twin Paradox":
Two identical twins are born on Earth: Cosmo and Terra. Being twins, of course, they are (almost) exactly the same age. One day, when both boys are 21 years old, Cosmo leaves the Earth on a super-futuristic rocketship moving at the speed of light (impossible, but just go with it). Cosmo travels one light year away from the Earth. What has happened?
Well, from Terra's perspective, Cosmo's ship appeared to move away at light-speed while Earth remained (relatively) stationary. Time, for Terra, has continued to pass at a "normal" earthdweller's pace. Cosmo, though, was seen travelling away from Earth at light-speed, and so Terra observes that time must have slown down for Cosmo. Consequence: From Terra's perspective, Terra is now the elder of the two twins.
BUT, from Cosmo's perspective, all of this is reversed. Cosmo actually observed the Earth rushing away from him at light speed while his super-futuristic rocketship appeared to remain stationary. Time, for Cosmo, passed at a "normal" earthdweller's pace, while from his perspective, time must have slown down for his brother, Terra. Consequence: From Cosmo's perspective, Cosmo is now the elder of the two brothers.
So, who's really older?
You'll have to ask a man smarter than myself.
2006-11-28 07:08:57 · answer #7 · answered by beckerj42 1 · 0⤊ 1⤋
it style of appears like that they'd attain earth collectively if considered through someone on earth. time might want to in straight forward words be slower for the individuals, if any, in the spacecraft. someone on earth is viewing both the solar and the spacecraft interior of an same reference body...
2016-10-07 22:17:35 · answer #8 · answered by ? 4 · 0⤊ 0⤋
Which light is at rest? I see it coming from all directions.
2006-11-28 06:58:20 · answer #9 · answered by John's Secret Identity™ 6 · 0⤊ 0⤋
NOT GETTING TO TECHINCAL,
OBSEVERING LIGHT HAS A TIME FACTOR INVOLVED.
WHAT YOU SEE NOW WAS THEN
2006-11-28 07:10:21 · answer #10 · answered by MOONDOG 1 · 0⤊ 0⤋