The causes of tides The tides are caused by two things. The moon’s gravitational force pulling on the oceans. The sun’s gravitational force pulling on the oceans. An eclipse does not cause the tides. It did not cause the so-called Supertide that enveloped Mont Saint Michel and London’s river Thames yesterday. The newspapers are getting it wrong, wrong, wrong, wrong, wrong. However, the eclipse and the supertide do have a common cause, which is a…
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…f spatial regions. However, William and the astronaut will agree about the order in which time-like separated events occur: first Harold is crowned, and then Harold is slain. Figure 1: An observer on Earth and an astronaut traveling away with velocity c/2 will describe two different foliations of spacetime into space-like hypersurfaces of simultaneity. On the other hand, an accelerating observer will not generally agree about the order in which th…
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…mass. This is not expected to happen at CERN according to any well-confirmed quantum theory, for reasons that have to do with uncertainty, and our consequent inability to squish that much mass-energy into lengths of the order of a very small R_s. However, some string theorists think that our four dimensions are just one surface of a many-dimensional world that we apparently can’t access. One consequence they derive is a much larger value for R_s…
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…in Penrose’s Conformal-Cyclic-Cosmology — indeed, this is apparently required in order to glue the aeons together smoothly. A remaining question, of course, is whether or not this is related in any useful way to the Boltzmann entropy on the scale of every-day objects… Second: the black-hole information paradox. As I’ve ranted before: black hole evaporation isn’t really a paradox, but rather a case where many physicists are demanding a more “comple…
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…author and reviewer, when everyone has access to the interwebs? An anonymized online interface would be quicker, easier, and more useful. In particular, it would allow for quick clarificatory questions, and even back-and-forth discussions of important results between author and reviewer, before a finalized report is submitted to the editor. Incentives for high-quality reviews. Most journals don’t offer you an incentive to do a good job in a timely…
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