| The Instantaneousness of Light and the Four Models . . . |
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Die folgende Arbeit von John F. Gogo befa?t sich mit den Fragen:
Wie kann man Lichtgeschwindigkeit definieren und wie kann man Lichtgeschwindigkeit messen?
The Instantaneousness of Light and the Four Models of Light Measurement
http://www.wbabin.net/physics/gogo.pdf
| Zitat: |
Abstract:
A third crucial experiment involving a one-way, two-clock measurement of light will reveal that all forms of light are ?seen? instantaneously and simultaneously by all observers. The principles of light constancy and relativity must be adjusted accordingly.
Introduction:
A. Bridgman
P.W. Bridgman asserted that from the Lorentz transformations the self-measured velocity of light is infinite, so it is not a physical velocity (1). He proposed no alternative theory of space and time to include an infinite self-measured velocity of light but he emphasized that this tack could lead to a theory, independent of the structure of light (2). The purpose of this paper is to propose such an alternative theory.
Bridgman spent much of his time concerned with the nature of light, particularly whether it is isotropic and whether the one-way velocity of light can be measured (3). According to Bridgman, in terms of performing all historical light experiments, the overwhelming consensus is that the two-way or go-come velocity has been measured in every experiment. This applies to Fizeau?s toothed-wheel experiment, the Michelson-Morley experiment, and the high accuracy measurements of Townes and Cedarholm. The only apparent important exception is Bradley's classical astronomical method in terms of the retardation of the time of the eclipses of the satellites of Jupiter when observed from different points in the earth?s orbit (4).
In this paper, it will be argued that there have been many one-way experiments performed, but they have not been identified properly. This has led to much confusion concerning special relativity theory. According to Bridgman two-way velocity measurement of light is essentially a one-clock function (5). One-way light measurement is essentially a two-clock function (6). After many years of analysis, Bridgman concluded that one-way two-clock velocity, one-way self-measured velocity, and two-way one-clock velocity are all indistinguishable (7). Therefore, Bridgman believed that it was impossible to perform a one-way light measurement.
B. Poincar? and Fizeau
Poincare?s (189 analysis of the epistemological problems inherent in defining a one-way light velocity was based on a variant of Fizeau?s well known 1849 measurement of the velocity of light which he accomplishes as follows:
Let a ray of light be emitted from point A at time ta as registered on a clock at rest at A; after traveling a known distance AB the light ray is reflected from a mirror at B and arrives back at A at time t?a (. From this, Fizeau measured the velocity of light to be:
C= 2AB/ t?A- tA (9).
Fizeau had assumed the equality of to-and-fro velocity and the isotropy of space for the propagation of light (10). Poincare addressed the question of whether cAB or cBA could be measured separately (11). He proposed placing a clock at B instead of A. Then the velocity of light cAB is:
cAB= AB/ tB-tA (12).
A vicious logical circle results since the measurement of (tb-ta) requires cAB? be measured without measuring a time (13). As a result, Poincare concluded that the one-way value was Fizeau?s ; and the proper definition of time is the one from Newtonian mechanics and is independent of the reference system?s motion, in agreement with our sense perceptions (14).
C. Einstein
Portions of Poincare?s analysis were rediscovered by Einstein in 1905, who pushed them to startling conclusions, not in agreement with our sense perceptions (15). After proposing in-principle operational definitions for distance and time, Einstein discussed a method for synchronizing clocks based on Fizeau?s procedure for measuring the velocity of light that is a Gordian resolution of the situation (16).
Einstein placed a clock at B, and then defined a common time for A and B through the equation
tB-tA = t?A-tB
which means cAB = cBA (17). Einstein did not need to consider these equations a definition, since the equality of to-and-fro velocities of light follows from the two axioms of relativity, which imply the isotropy and homogeneity of space for light propagation (1. Without the two axioms of relativity, the placing of clocks at A and B would not have removed the vicious logical circle exposed by Poincare nor the necessity for Fizeau?s implicit assumptions (19). Having broken the vicious logical circle of clock synchronization, Einstein defined the one-way velocity of light as cAB = cBA = c, where
c = AB/ tB-tA (20).
(Zitatende) |
Lesen Sie bitte weiter unter:
The Instantaneousness of Light and the Four Models of Light Measurement
http://www.wbabin.net/physics/gogo.pdf
Beste Gr??e Ekkehard Friebe
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