Why aren't different observations of the same event simply optical illusions?

Happy Recluse

The starting point for special relativity is the thought experiment. These experiments generally describe two different observations of a single event, and the experiments assume that both observations are true. To be clear: the assumption is that both of the different observations of one event correctly reflect that event. Usually in such cases, we conclude that both observations are not true; we decide that an optical illusion is at work here. Yet, the argument for SR assumes that both observations are true. Doesn’t Ockham’s razor suggest that an illusion is at work, and so there need not be radical and counter-intuitive theory of time? Why not?

Some people appeal to inertial reference frames to avoid the appearance of a contradiction between the different observations. The argument suggests that Observation A shows light behaving one way in that reference frame, and that Observation B shows light behaving in another way in another reference frame. The theory says that no contradiction exists because the obervations are dependent on different reference frames. At this point, no one objects to the conclusion that from this perspective everyone will see X, and from that perspective, everyone will see not-X. Presently, we have information about the observations, and no claims (yet) about the single event under consideration. The objection occurs when we believe that the observations truly refer to the event and no longer about the observations.

Here’s an analogy. I see a man at a distance and my observation shows that he is small. Another person sees him nearby and that observation shows that he is large. No one assumes or concludes that the man is small and large. One (or both) observations are illusory.

Following the analogy, using the “reference frame” argument demands that we think insists that the man really is small in this frame and that the man really is large in that frame. But no matter how we stress the words “really is,” appeals to the reference frame still speak only of observations from different perspectives. No contradiction occurs if we reflect on the observations; the contradiction follows when we think the observations say something about the object. Namely, that the man is small and large.

Returning to my question, it seems much simpler to think there is an optical illusion between different observations than to think both observations are true and then to develop a theory of time to explain the differences in observation. So, why not employ Ockham’s razor and dispatch SR?

Meir Achuz

You are almost on the right track, but that does not dispute SR.
See the first section of http://arxiv.org/abs/0906.1919