Now back from a trip to the West Coast, here are some accumulated things that may be of interest:
- One thing I didn’t do while there was attend the 2020 Breakthrough Prize symposium. For videos of three talks about supergravity, see here. At the time of the award I wrote here about why a \$3 million prize for a failed idea about particle theory was a bad idea. Listening to the talks, I think an even worse idea is telling the public that this is a great example of why they should trust science.
- For another dubious idea from the West Coast, in January the KITP is bringing high school teachers to Santa Barbara to teach them about Spacetime, Holography, and Entanglement. Most of the programs the KITP has run for teachers (see here) have been devoted to explaining important, solid science. Back in 2001 when they promoted string theory I thought that was a bad idea, this latest one isn’t much better. Again, when the credibility of science is under attack, why go to the public (or, in this case high school teachers) to promote a highly speculative research program? Is it really a good idea for high school teachers to be exposed to this kind of hype, presumably with the hope that they’ll somehow transmit it to their students?
- On the evergreen topic of bad multiverse science, Scott Alexander here defends multiverse speculation, responding to Jim Baggott’s article. He and the authors of the more than four hundred comments debate at length a red-herring issue. Alexander writes:
My understanding of the multiverse debate is that it works the same way [as respectable paleontology]. Scientists observe the behavior of particles, and find that a multiverse explains that behavior more simply and elegantly than not-a-multiverse.
Yes, if theorists had a simple, elegant multiverse theory with lots of explanatory power, you could get into interesting arguments about its testability and whether the idea was solid science or not. The problem is that no such multiverse theory exists. If you want to talk about the MWI multiverse, your problem is that solving the measurement theory problem by just saying “the multiverse did it” may be “simple” and “elegant”, but it’s also completely empty. If instead you want to talk about the cosmological multiverse, the problem is that you don’t have a theory at all (and the actual fragments of a theory you do have are complicated and ugly). For more about this, see my posting and article on Theorists Without a Theory.
For something more positive, while traveling I noticed two quite interesting articles which explain in a detailed technical way approaches to two of the great unsolved problems of our time, while carefully discussing why the approaches have not (yet?) worked, leaving the great problems unsolved.
- For mathematics and the Riemann Hypothesis, see Alain Connes and Caterina Consani’s article The Scaling Hamiltonian, about the attempt to understand the zeros of the Riemann zeta function in terms of the properties of a specific Hamiltonian operator, which in some sense is a generator of a group of scaling transformations.
- For physics and quantum gravity, see Donoghue’s A Critique of the Asymptotic Safety Program, which has a detailed discussion of the problems with making sense of both quadratic gravity Lagrangians and the idea of a non-trivial fixed point gravity theory theory. I was interested to see that he has a lot to say about the Lorentzian vs. Euclidean signature issue, something often ignored.
Finally, I recommend reading Elizabeth Landau’s interview at Quanta with astronomer Virginia Trimble and Trimble’s excellent advice to us all:
Pay attention. Someday, you’ll be the last one who remembers.
Update: Two more math-related items well worth a look:
- Dan Rockmore at the New Yorker on Where do ideas come from?
- A profile of Terry Tao at the Princeton Alumni Weekly.
Update: Yet another blog entry from Scott Alexander about the multiverse, with more hundreds of comments. What is it with the fascination for this empty argument?
At BBC Science Focus, more multiverse promotion from Sean Carroll. He does end though by getting to the real point (note that when theoretical physicists say a question is “hard to answer”, it means they have no idea how to answer it):
Many-Worlds is a lean and mean theory, but it’s possibly too lean and mean; there is very little structure to rely on, so questions like “Why do probabilities behave the way they do?” and “Why is classical mechanics such a good approximation to the world we see?” are hard to answer.
This is exactly the problem that those arguing over this at Slate Star Codex and elsewhere don’t seem to understand: saying “all is the Schrodinger equation” doesn’t tell you how to connect the theory to the world we observe. Adding in an ontology of multiple universes does nothing at all to solve this problem.
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