Hammar-Experiment

The Hammar experiment was a by Gustaf Wilhelm Hammar (1935 ) by run physical experiment to check the possible entrainment of the ether ( a hypothetical medium for the propagation of light ). It has given an unsatisfactory result, that is, there could be no Äthermitführung be determined and is in agreement with the predictions of the theory of relativity. For further experiments, see also Tests of special relativity.

Overview

In the 19th century it was believed that light propagates in a medium, the ether, just as sound propagates in air. The relative motion between matter and ether was called ether wind, and should be experimentally detectable. However, by the Michelson - Morley experiment and its repetitions, as well as other experiments, it was shown that this ether wind does not exist. This was an important step in the development of special relativity. A possible way out of the ether theory was hypothesized that the etheric bodies will be fully carried. However, this hypothesis could not be confirmed by the experiments of Oliver Lodge (1893-1897), who observed the propagation of light between rotating disks and no interference noted.

In the 1920s, Dayton Miller repeated the Michelson - Morley experiment at higher altitudes and received a seemingly positive result, with an ether wind speed of around 10 km / s This would contradict the special theory of relativity. However, these measurements were immediately refuted by further measurements of other researchers who were able to reproduce even at high altitudes no positive effect. Miller said, however, that the different experimental setups were more shielded and thus occurred a larger ether entrainment effect, which have caused the negative results. Although Miller's results were not credible by these negative results of other experimenters, led Hammer ( 1935) won an interferometer experiment, should be tested with the Miller's acceptance of an additional entrainment due to the shielding, and the more accurate than the older experiments of Lodge had.

Experimental setup and result

By means of a half-silvered mirror, a beam of white light A has been divided into two half- beams. A half beam was directed in transverse direction in a tube which was surrounded by massive lead blocks. There, the beam from the mirror D is reflected and transmitted in the longitudinal direction of the mirror at the other end C of the tube. From there he was sent in the transverse direction from the tube to mirror B, and from there turn in longitudinal direction back to mirror A. The second half of the beam traversed the same route in the opposite direction. Then both beams were made ​​to interfere. If the ether carried more in the jacketed arm, a different term for the opposite rays is obtained according to the equations:

Where the velocity of the entrained ether is. This results in a time difference of:

However, the result was negative, that it was not observed fringe shift, which due to the measurement accuracy, an upper limit for the entrainment speed of km / s was found. This contradicts the assumption that the etheric bodies are present on the surface, and confirms the prediction of special relativity.

General information on Äthermitführung

There are different ideas as to Äthermitführung, each of which was refuted by special experiments:

• No or partial entrainment by all bodies: Refuted by the Michelson - Morley experiment and repetitions.
• Full entrainment in or near all the body: Refuted by the aberration of light, the Sagnac effect, lodges ' experiments, and the Hammar experiment.
• Full entrainment only by large masses like the Earth or other celestial bodies: Refuted by the aberration of light, and the Sagnac effect due to the Earth's rotation (measured with GPS or the Michelson - Gale -Pearson experiment).