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Physics, Astronomy & Cosmology / What have I missed regarding This Einstein thought experiment?
« on: 18/03/2018 18:36:01 »
Consider Einstein’s thought experiment in which he imagines himself travelling at a speed that is approaching that of light, holding a mirror in front of his face. If, as was believed at the time, light travelled at about 300,000kps relative to the aether, then, as Einstein and his mirror reached the speed of light, the light trying to leave his face would not do so, and would therefore not reach the mirror, so would not be reflected back. In this thought experiment, as Einstein reached light speed his reflection vanished from the mirror. Einstein reasoned that this ran contrary to Galileo’s concept of relativity. According to which, someone travelling at a constant velocity, without reference to any object outside his or her frame of reference, should not be able to distinguish between being in motion and being stationary. If one were not able to see one’s reflection in the mirror, in which the reflection was visible when stationary, then one would have an experiment to distinguish between being stationary and being in motion.
Recast Einstein’s thought experiment in terms of Galileo’s below-deck scenario: a sailor would know if the ship were moving at the speed of light because his reflection would vanish. In Galileo’s scenario all the insects etc. move within the moving cabin exactly as they did in the stationary cabin because the entire system is moving in unison. If one shone a light across the cabin its speed would be measured as 300,000 kps, whether the ship was moving or not.
Prior to Einstein’s discoveries it would have been assumed that this was because the speed of the ship was being added to, or subtracted from the speed of light, as would be the case with the various creatures in Galileo’s scenario. Until Einstein came to the conclusions that arose out of his thought experiment it would have been reasonable for him to assume that the speed of the light leaving his face would have been measured as 300,000 kps, plus his speed through the aether. Thus, why would he have concluded that his reflection would vanish from the mirror when he travelled at light speed?
Until he made his later discoveries, would he have had any reason to assume that the light travelling from his face to the mirror would have been measured as anything other than almost 600,000 kps by an observer outside his RF? Unless, of course, Einstein’s motion through the aether caused an aether wind which effectively reduced the light’s speed between Einstein and the mirror to zero as he reached light speed. To avoid this, Einstein and his mirror would have to be completely shielded from the aether, apart from a small portion which they carried with them in their RF, in order to equate this thought experiment with that of Galileo and his below-deck goings on.
It seems as though it would have been necessary to have been in possession of the conclusions drawn from Einstein’s thought experiment in order to have been able to formulate and analyse it.
Recast Einstein’s thought experiment in terms of Galileo’s below-deck scenario: a sailor would know if the ship were moving at the speed of light because his reflection would vanish. In Galileo’s scenario all the insects etc. move within the moving cabin exactly as they did in the stationary cabin because the entire system is moving in unison. If one shone a light across the cabin its speed would be measured as 300,000 kps, whether the ship was moving or not.
Prior to Einstein’s discoveries it would have been assumed that this was because the speed of the ship was being added to, or subtracted from the speed of light, as would be the case with the various creatures in Galileo’s scenario. Until Einstein came to the conclusions that arose out of his thought experiment it would have been reasonable for him to assume that the speed of the light leaving his face would have been measured as 300,000 kps, plus his speed through the aether. Thus, why would he have concluded that his reflection would vanish from the mirror when he travelled at light speed?
Until he made his later discoveries, would he have had any reason to assume that the light travelling from his face to the mirror would have been measured as anything other than almost 600,000 kps by an observer outside his RF? Unless, of course, Einstein’s motion through the aether caused an aether wind which effectively reduced the light’s speed between Einstein and the mirror to zero as he reached light speed. To avoid this, Einstein and his mirror would have to be completely shielded from the aether, apart from a small portion which they carried with them in their RF, in order to equate this thought experiment with that of Galileo and his below-deck goings on.
It seems as though it would have been necessary to have been in possession of the conclusions drawn from Einstein’s thought experiment in order to have been able to formulate and analyse it.