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| BACKGROUND SPECIAL RELATIVITY The theory of Special Relativity is based on the postulate that all inertial coordinate systems are equivalent, concerning the formulation of physical laws. This means that even if such coordinate systems are moving at constant speed relative each other, each and one of them can be considered to be at rest (relativity principle). A moving object observed in one such a coordinate systems can have different speeds and directions as observed in other such systems, but if the motion is accelerated, the amount of acceleration is the same for all observers and Newton's laws of inertia apply in all these systems. Such coordinate systems are therefore called inertial systems. This postulate excludes the possibility of absolute motion; all motion is relative. More than 300 years ago Isaac Newton claimed to have proven the existence of absolute rotation by watching how the water level in a rotating bucket rises up against the inner surface of the bucket Through this, he claimed, the water is rotating in a absolute sense, rather than merely relative the bucket or any other system of reference. The observed invariance of the speed of light as measured by all observers, regardless whether they are moving relative oneanother or not, indicates that there cannot be such a thing as absolute motion nor absolute space for that matter. Nevertheless, as the acceleration of moving objects is the same in all inertial systems where they are observed, the question arises if these accelerated motions are absolute ones as claimed by Newton. Let us, with far more sophisticated means than Newton had available, investigate again the subject of absolute rotation. Consider what an observer would see who is placed in a satellite at geostationary orbit around the Earth. His satellite orbits around the earth in 24 hrs and will therefore always be seen 'hanging' above the same location on Earth's surface. The observer on board of this satellite will also see the same scene on Earth; he cannot observe the rotation of the Earth around its polar axis. From what he sees, he can make three possible conclusions:
If we consider this experiment to be isolated from the Solar System, meaning that we just have a planet, a satellite and a steady background of fixed stars, all these three considerations are equivalent, according to the principle of relativity. This means that there would be no experiment that could give either of them a preferred position. If it were possible, then that position would imply absolute rotation as Newton saw it. | |
Fig. 1
| The consequence of this is that an observer on Earth cannot hit the satellite with a laser beam if he points it in the sighted direction; he will miss it with 400 meter or 2 arc second 'behind' the satellite! (fig. 1b) |
Fig. 2
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2) If the Earth is considered to rotate around the satellite, an observer on Earth will always see the satellite in its correct position because it doesn't move relative Earth. The observer in the satellite will now not be able to hit a sighted location on Earth's surface with a laser beam. However, an observer on Earth will now be able to hit the satellite with a laser beam, if he points it in the sighted direction |
| 3) If the Earth and the satellite are considered not to rotate at all, which means that the background of fixed stars is perceived to rotate around the center of the disk as observed, both observers will hit their targets if they point a laser in the sighted direction. To my knowledge the a.m. experiment has never been made and it would really be exciting to know what the outcome of it would be. There is however an equivalent experiment that can be made in a laboratory on Earth. A laser gun is fixed placed in the center of a rotating disk and pointed to a (point) detector at the disk's periphery. If there is no absolute rotation, the gun will always hit the detector, regardless the rotational speed of the disk. If it does not, the situation is not symmetrical (relativity principle), compared with changing places of the gun and the detector, in which case the gun surely would hit the detector under all circumstances! If the outcome of such an experiment is not acknowledged, because the object at the disk's periphery is accelerated (inertia) towards the center of it, I refer to the a.m. experiment with the satellite, where no inertia occurs. At least, we could conclude, that our understanding of inertia is incorrect ! ( I have reinterpreted the laws of Newton, to eliminate this inconsistency. Read the full theory here.) The above I wrote several years ago, but today (April 2, 2007) i found the following web page: The above was about rotation, but we can also consider an other experiment with constant, linear speeds, showing that the relativity principle is wrong. Consider an object that moves away in a straight line from an observer and at constant speed. If the observer sends a laser pulse to the object, that reflects it back, he can calculate the distance of the object in the moment of reflection, by multiplying the time sequence with the speed of light and dividing the result by two. If we now assume that the object is at rest and the observer is moving away instead, we will see that he with the same procedure will measure a larger distance! Of course, the real distance between object and observer is at any moment the same in both ways, but the observations are not (make a situation sketch yourself and you will see). In "real life" the problem would not exist, because we cannot generate a uniform motion without constantly applying mechanical energy to the moving object (we cannot eliminate the effects of friction and gravity) and then it is fully clear what moves and what does not. Moreover, even in free space (orbits around Earth) there cannot be uniform motion, without constantly applying mechanical energy (a working force) to the moving object. From this I conclude that uniform free motions cannot be physical reality and hence, al models based on such motions must be deceptive ...like the ones Einstein used. On the next page we will more in detail study the relativity principle itself, and analyze the imaginary experiment that Einstein used to relativate the equations of Lorentz.
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