ASTRON 2B03 Lecture Notes - Lecture 13: Grandfather Paradox, Length Contraction, Blueshift
6 Nov 2015
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Friday, october 9 (see marking scheme for details) Light beam going to the right x the right. Remember look- back time ? the past (earlier times) All the events that we might influence our elsewhere. All the events that can affect our here and now . In the future the event may be within our light cone. In the future the event may be within our light cone x. Claim: nobody (really, no information) can travel faster than light. Similar discontinuous things also happen when you go faster than sound . Without causality the entire structure of physics falls apart. Causes must come before effects, or it becomes impossible to make predictions. Real reason is to do with causality: there is no consistent picture of how the future springs out of the past if information can travel faster than light. Idea very similar to the reason why you cannot travel back in time.
