...the famous assertion by Einstein that the length of a rod depends on its velocity and on the chosen definition of simultaneity. ...is based on the fact that we do not measure the length of the rod, but its projection on a system at rest. How the length of the projection depends on the choice of simultaneity can be illustrated by reference to a photograph taken through a focal-plane shutter. Such a shutter... consists of a wide band with a horizontal slit, which slides down vertically. Different bands are photographed successively on the film. Moving objects are therefore strangely distorted; the wheels of a rapidly moving car for instance, appear to be slanted. The shape of the objects in the picture will evidently depend on the speed of the shutter. Similarly, the length of the moving segment depends on the definition of simultaneity. One definition of simultaneity differs from another because events that are simultaneous for one definition occur successively for another. What may be a simultaneity projection of a moving segment for one definition is a "focal-plane shutter photograph" for another.
Hans Reichenbach
» Hans Reichenbach - all quotes »
If the definition of simultaneity is given from a moving system, the spherical surface will result when Einstein's definition with ? = 1/2 is used, since it is this definition which makes the velocity of light equal in all directions.
Hans Reichenbach
We define: any two events which are indeterminate as to their time order may be called simultaneous. ...Simultaneity means the exclusion of causal connection. ...Yet we must not commit the mistake of attempting to derive from it the conclusion that this definition coordinates to any given event at a given different place. This would be the case only for a special form of causal structure, a form that does not conform to physical reality.
Hans Reichenbach
Take movement for example. Forces acting up, down, or from side to side. You make theories to explain it all, but you might well remember that it was you that invented them all. For Mach there was no reason to believe the rest of the cosmos was doing what your little bit was doing, so science should only describe not try to explain. Even description is relative. Am I moving or is the back ground? Or take the position of a star. It depends on the position you see it from, which depends on the date and time, which in turn depends on the position of the earth, in a solar orbit, in a solar system, moving around the edge of a Galaxy which may be moving away from other Galaxies. Say that you've decided that I'm moving and the background is standing still. Is the background moving relative to something else?
James (science historian) Burke
No man, not even a doctor, ever gives any other definition of what a nurse should be than this — "devoted and obedient." This definition would do just as well for a porter. It might even do for a horse. It would not do for a policeman.
Florence Nightingale
We will freedom for freedom’s sake, in and through particular circumstances. And in thus willing freedom, we discover that it depends entirely upon the freedom of others and that the freedom of others depends upon our own. Obviously, freedom as the definition of a man does not depend upon others, but as soon as there is a commitment, I am obliged to will the liberty of others at the same time as my own. I cannot make liberty my aim unless I make that of others equally my aim.
Jean-Paul Sartre
Reichenbach, Hans
Reinfeldt, Fredrik
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