We've measured the speed of light to accuracies greater than +/- 9 m/s, and funnily enough the measurements happen to match the value of c you can calculate from Maxwell's equations. Besides, the earth isn't at a constant distance from the Sun in it's orbit, so the affect of the Sun's gravitation should be making the speed of light measured on earth vary according to the seasons, an effect we certainly do not see. Your hypothesis doesn't stand up to observations.
GMontag, You're wrong. Many aether-detection experiments done over the years have measured a variation in the speed of light far larger than 9 m/s. But even these larger deviations are considered within the margin of error compared to the 30,000 m/s speed that was, and is still, expected. The speed of the light would not only vary by season, but would also vary by the time of day, if we had an instrument accurate enough to measure these small changes. Dayton Miller made an inferometer that not only detected a change in the speed of light, but also found a correlation between these changes and the rotation and the revolution of the Earth. Unfortunately, the results of his experiments were never taken seriously by the scientific community (although Einstein got scared), and were only challenged after Miller died when he couldn't defend his work.
It was indeed Ronald Hatch I was referring to. However, the group that did the study on FTL were very much mainstream and have not been labled. James R. has a bad habit of making deragatory assumptions like referring to sombody as a "quack" rather than address the message he attacks the messenger.
You are leaving out another postulate of light: Light motion is isotropic and moves indeopendently to the motion of the source of the light. This postulate is is conveneiently omitted by yourself in the tutorial Let us look at the problem slightly different using only the distances traveled by the emitted light. In a time t the L and R photons (left and right photons) each move a distance ct. L strikes the oncoming LC (left clock/mirror) after moving ct, ergo the LC has moved a distance vt (v is unknown at this time). R has also moved a distance ct and is a distance 2vt from RC. Here both photons have moved a distance ct from the emission point P. L is detected and reflects a distance ct back to the emission point P after moving another distance ct. R must cross the distance 2vt plus a distance the frame moves in the time t' that R catches RC or, ct' = 2vt + vt', where t' = t(2v)/(c - v). t' is the time that R is detected by RC after L was detected by LC. In terms of velocity, v = ct'/(2t + t') After L has traveled a total of ct (outbound and inbound) L is located at P, which verifies the invariance of the point P defined by the equal motion of the L and R photons. L is located at The emission point p, which has not moved, and L is located 2vt from the physical midpoint of the LC and RC which is moving away from L. At this instant, R is located a distance 2vt + 2vt' from the oncoming physical midpoint of LC and RC. The frame moves a distance vt' as L and R photon converge simultaneously at M, now located a distance 2vt + vt' from the initial emission point of the L and R photons. Light moves isotropically and independent (straight-line trajectory at constant velocity c wrt the point of emission of the light) of the motion of the source of the light until acted on by external forces. These positions must be referenced to the point if emission of the photons not from the physical emission point on the frame, which is be moving. The observer on the frame has no physical data to assume his frame is at a state of rest. The observer knows only that he is at rest with respect to the frame. Why do those pushing special relativity theory want to grant super observational powers to on observer in an enclosed environment, who is completely ignorant of the laws of physics? The statement here is correct only if measured wrt the point of emission of the photons and if the frame is not moving wrt P, the emission point of the light. The positions of the clocks at each end of the rod do not change distances with the physical center of the rod, true, but one must ignore the physics of the light motion, that moves independently of the moving frame, remember? Putting "'" primes on the time statement does not change anything. Whether the observer is on the frame or not, the light will move the same velocity as seen from the stationary frame and will arrive at the moving LC (left clock), moving with respect to the invariant position of the point of the emitted light. The photon moves ct, which is vt short of the length of the midpoint of the physical frame (distance d in the James R world) to the LC, left clock. The left photon will arrive at the Left clock a distance vt short of the physical distance between the frame midpoint and the clocks. This statement of James R above is totally bogus. James R is negating the concept of motion here by ignoring the motion of the frame and inducing erroneous motion attributes to light based on the mere presence of a human observer.This is what SRT is, a psychological aberration. Again, James R ignores the invariance in the point P and effectively negates the very concept of motion. The light emanating from the midpoint of the moving frame is only measured properly wrt to the emission point not the physical midpoint of the LC and RC clocks, which are erroneously assumed to be in a state of rest. Noway can the observer accumulate data that shows the photons arriving simultaneously at the LC and RC clocks. You can do it in owrds on paper, but you must ignore the isotropic motion and constant velocity of light to do do, in other words you must ignore the postulates you proclaim as governing the motion of light. James R, light is measured from P, the point of emission of the photons, Your assumption that the observer can measure everything from the physical midpoint is bogus. You negate the concept of moption by doing so. You also violate the postulate of light that says the speed of light is independent of the motion of the souirce of light, yet you blithely continue on measuring light motion as if the speed of light were somehow attached to the moving frame. Your tutorial on simultaneity is a testment to the massive scientific misconceptions surrounding the history of SRT. Take any point P in the universe and emit two photons simultaneously. All measurements wrt the point P are done with regard to the motion of light. Each photon moves the same distance from P in the same amount of time. Each photon moves in a straight line trajectory, on the same trajectory line. If one of the photons is reflected 180 degrees after moving a distance ct from the emission point the photon will return to the emission point P after moving an additional distance ct. This is further verification of the invariance of the emission point P. Your moving frame scenario does not work properly as you assume erroneously that the frame is not moving. This assumption is made withuout any scientific data. After the photons reflect and converge at the moved physical midpoint may the observer make assumptions regarding frame motion. To do so before the data is all in is pure speculation. Assume the observer has reams of test data where the frame is statioanry wrt the embankment and reams of data where the experiment is conducted withthe frame is moving at a uniform velocity v. The times for the round trip are different and the observer on the moving frame will be able to detemine his absolute velocity with respect to the invariant point P, sitting nicely at an absolute zero velocity. [thread=46658]Here is an absolute zero velocity frame of reference system[/thread] ---- James R get your references straight. The light is moving with respect to the point of emission of the light, point P, not wrt the physical midpoint of the frame that is moving. It is your ignorant obsevers that that are screwing up measurements. You must have a talk with them. Intuition has nothing to do with a system that ignores the laws of motion of light. 1) Light moves isotropically and independently to the motion of the source of light and 2) the speed of light is a constant c measured wrt absolute zero velocity. Geistkiesel Please Register or Log in to view the hidden image!
superluminal, The speed of light has only been measured to be c in devices that are stationairy on the surface of the Earth (stationairy relative to the Earth's gravitational field). The speed of light has never been measured in a device that is actually moving through a gravitational field.
The speed of light is not 'c' on the surface of the Earth, it is defined to be 'c' in a vacuum. Is anyone aware of any experiment where the speed of light has been actually measured as 299,792,458 m/s or within a few m/s of this value, such as within a vacuum chamber? The speed of light in Earth's atmosphere is about 99.97% of 'c', or appox. 299,702,520 m/s, almost 90,000 m/s less than 'c'. And no, bouncing laser beams off the retroreflectors on the moon does not time the speed of light, it gives the distance to the moon based on a constant speed for light, a defined value.
2inquisitive, Let me rephrase my statement. I meant to say that it has only been proven that the speed of light remains constant in a device that is stationairy on the surface of the Earth, irrespective of the Earth's relative motion to the Sun, Solar System, or Galaxy.
http://galileoandeinstein.physics.virginia.edu/lectures/spedlite.html Romer did this in 1676. I've posted this before. Light leaving Jupiters moons and arriving at earth goes through multiple gravitational field changes and still moves at 186,282mi/s.
Romer came up with about 125,000 mi/s. It was later changed to reflect 'more accurate' measurements for orbital distances. Superluminal, tell me how the distances to the moons is determined. Couldn't be by measuring the time travel of EM radiation (light or radar) could it? Like we measure the distance to our own moon by light travel time?
superluminal, Through most of the journey, the light is passing through the Sun's gravitational field. And as you know, Jupiter and the Earth are in relatively fixed orbits around the Sun. Now, if the Earth and Jupiter were both moving at a high speed towards, or away, from the Sun when the measurement was done, the measured speed of the light would not be 186,282 mi/s.
Well, so say you guys. I will bet however that c is measured to be c no matter how the source is moving. If it's not then much of physics, that has already been proven correct, would have to be wrong.
What about space probes that are moving away from earth at fiarly high speeds? NASA calculates the signal travel times and gets them spot on even way out at Saturn!?!?
NASA uses Newtonian Orbital mechanics to do that. Heh, not a good example, superluminal. Now don't get upset!
2inq, Upset? Me? I'm not talking about orbital mechanics, dude. I'm talking about the radio signal (light) travel times as calculated using 186,282 mi/sec that NASA uses to determine when a response is expected from a command sequence. Spot on all the time. I'd expect problems to be seen if c varied with the relative velocity between the earth and the probe, wouldn't you?
superluminal, Experimental evidence wouldn't be wrong, it would just have an alternate explanations. Let me give you an example: As you know, atomic clocks that are travelling at high speeds through our atmosphere were shown to tick slower than clocks that are on the surface of the Earth. A relativist will claim that this is proof that time is dilating, and therefore SR is correct. However if you assume that the omnidirectional speed of light is only c for an observer that is stationairy in a gravitational field, then the speed of light in an object that is moving through a gravitational field will change. It is then easy to calculate that the average speed of light in that object (the average speed of light travelling in all directions) will decrease. Since the average speed of light decreases, the speed of almost all reactions in that object will decrease. Even circuit boards will work slower because the average speed of the electric field travelling through the conductors would decrease. Now since clocks don't measure time directly, but instead measure the speed of certain reactions, the ticking of the clocks would slow down.
Pro, Ok. If this were the case how would you distinguish time slowing from a slowing of c (and all physical activity associated with it) that made it seem as though time were slowing?
superluminal, You couldn't do it directly, but you could do it indirectly: First, you'd measure the speed of light in an object that is moving at a high speed through a gravitational field. Then, using those values, you'd calculate the time it would take for an electric field to make a loop in a circuit if the entire circuit was moving at that speed through that field. Then you would physically send the circuit at that speed through a gravitational field and measure the time it would take for the electric field to make the loop. Finally you would compare the measurements with your calculations. If they were equal, then there is no time dilation, if they're not, then there is.
Not so SL. Look at the Sagnac Effect it tells a different story. If One measures the SOL wrt v = 0 and gets the value C, then what does this say about always measuring the SOL wrt any moving frame ? It says the relative velocity of frame and phioton is c - v or c + v. It says the assumption that the relative velocity of frame and photon is not c. You see, SL, SRT negates velocity of the moving frame that is how it is done mathematically as well as physically, it, SRT, isn't physics. As soon as one obtains an absolute velocity v = 0, SRT crashes. Your statement thta SOL is measured C needs revision to exclude the measurement of the relative velocioty of frame and photon.
1) Pro, The signal in the circuit will always be seen to take the same time to propagate by an observer travelling with the circuit. 2) Geist, Once again: http://www.mathpages.com/rr/s2-07/2-07.htm From the above article: Absolute velocity is non-existent. Conclusively show the existence of an "ether" or yield to the power of the dark side. Mwahahaha!!!
