We apply an online optimization process based on machine learning to the production of Bose-Einstein condensates. BEC is typically created with an exponential evaporation ramp that is optimal for ergodic dynamics with two-body s-wave interactions and no other loss rates, but likely sub-optimal for real experiments. Through repeated machine-controlled scientific experimentation and observations our ’learner’ discovers an optimal evaporation ramp for BEC production. In contrast to previous work, our learner uses a Gaussian process to develop a statistical model of the (...) relationship between the parameters it controls and the quality of the BEC produced. We demonstrate that the Gaussian process machine learner is able to discover a ramp that produces high quality BECs in 10 times fewer iterations than a previously used online optimization technique. Furthermore, we show the internal model developed can be used to determine which parameters are essential in BEC creation and which are unimportant, providing insight into the optimization process of the system. (shrink)

In a pair of very important papers, namely “Space, Time and Individuals” in the Journal of Philosophy for October 1955 and “The Indestructibility and Immutability of Substances” in Philosophical Studies for April 1956, Professor N. L. Wilson began something which badly needed beginning, namely the construction of a logically rigorous “substance-language” in which we talk about enduring and changing individuals as we do in common speech, as opposed to the “space-time” language favoured by very many mathematical logicians, perhaps most notably (...) by Quine. This enterprise of Wilson's is one with which I could hardly sympathize more heartily than I do; and one wishes for this logically rigorous “substance-language” not only when one is reading Quine but also when one is reading many other people. How fantastic it is, for instance, that Kotarbinski1 should call his metaphysics “Reism” when the very last kind of entity it has room for is things —instead of them it just has the world-lines or life-histories of things; “fourdimensional worms”, as Wilson says. Wilson, moreover, has at least one point of superiority to another rebel against space-time talk, P. F. Strawson; namely he does seriously attempt to meet formalism with formalism—to show that logical rigour is not a monopoly of the other side. At another point, however, Strawson seems to me to see further than Wilson; he is aware that substance-talk cannot be carried on without tenses, whereas Wilson tries to do without them. Wilson, in short, has indeed brought us out of Egypt; but as yet has us still wandering about the Sinai Peninsula; the Promised Land is a little further on than he has taken us. (shrink)

We can best begin from Wilson's "simple little puzzle" about Caesar and Antony: "What would the world be like if Julius Caesar had all the properties of Mark Antony and Mark Antony had all the properties of Julius Caesar?" Wilson's own approach to an answer is indirect--he begins by telling us not what such a world would be like but what it would look like. "Clearly the world would look exactly the same under our supposition." But this assumes that the (...) question "What would such a world look like?" is a proper one; which it surely is not. For his answer to it is meaningless until he specifies to whom this supposed world would look as he says it would. It would look exactly the same to him or to me; but would it have looked the same to Caesar or to Antony? In fact Julius Caesar had the experiences of being called "Julius Caesar," being murdered on the Ides of March, and so on, and these are very different experiences from being called "Mark Antony," dallying on the Nile with Cleopatra, and so on; so I don't see how this alternative course of events could possibly have looked the same to Julius Caesar; or--using a similar line of argument--to Mark Antony. So I cannot agree that, as Wilson goes on to say, "our attempt to describe a distinct possible world has produced just the same old world all over again." I am not, indeed, convinced that even a world which looked to everyone just as the actual one does would necessarily be the same world ; but even putting this doubt aside, since the world mentioned wouldn't look to everyone as the actual world does, it wouldn't be the same even by Wilson's own standards. (shrink)

A. N. Prior; XIV—Time, Existence and Identity, Proceedings of the Aristotelian Society, Volume 66, Issue 1, 1 June 1966, Pages 183–192, https://doi.org/10.1093/.