1. GRrrrr part 1.

    So they've found gravitational waves. Damn.

    This post is not a report about that; I don't understand it well enough to report. This post is the first in a two-part report about my confusion and chagrin.

    Let's start with the chagrin; I'd been hopping without hope that gravitational waves would never be found. Like all good scientists should I had been hoping the accepted wisdom was wrong. The tackling of such errors is how science progresses.

    But why pin my hopes on gravitational waves in particular? They seem innocent enough as consequence of the central equation in general relativity -- the Einstein equation, which relates gravity to space-time curvature, and that to energy and hence to mass and thence back again to gravity. When you squint at the Einstein equation the right way it turns into perfectly good wave equation.

    The doubts creep in when you consider the energetics. Like all waves, they should carry energy away from their sources, and indeed our first observational evidence for gravitational waves was of two block-holes loosing energy as they orbited each-other.

    But defining gravitational energy is a tricky and fraught issue -- you can even write down the law of conservation of energy in ...

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  2. The Linked List (5.11.2015)

    I just scanned 200 science posts, so you don't have to.

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  3. Highlights: Emergent Quantum Mechanics 2015

    Weekend before last, I went to the 3rd Emergent Quantum Mechanics Symposium at The Vienna Institute of Technology (TU Wien). This is a picture of what other people at TU Wien were doing Car
trajectories

    The symposium was even more exciting than the car racing. Or at least it was first conference I'd been to since I stopped being a physicist; and perhaps as a result I was a lot more excited about it than I was at any of the conferences where I had any actual business.

    As its name suggests, this conference was about the foundations of quantum mechanics. Moreover, it was motivated by the search for a deeper reality that explains the mathematical rules of quantum mechanics (QM). This is not the kind of thing you would feel an itch for if you think no such reality exists; thus the symposium was dominated by scholars who either have such a realist itch or at list had something to say about how it might or might not be scratched.

    I don't have the journalistic skill to write a fair report of the whole thing; there were too many good talks. But I can briefly describe, and link to the things ...

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