## the calculating stars [book review]

Posted in Books, Travel with tags , , , , , , , , , , , , , , on October 16, 2021 by xi'an

This fist sounded like an interesting attempt at alternate history, when a massive meteor strike obliterating the Washington DC region in 1952 forced the World to change shift towards space exploration and the eventual evacuation of Earth. The story is told from a computer (or computress) viewpoint, who is a wunderkid, a mathematician, a physicist, a war (WASP) pilot, and more, with a strong will and an independent mind, hoping to become a female astronaut. If the setting reminds you of Hidden figures, a (great) movie about the true story of NASA black female mathematicians, it is no surprise and I wonder how much inspiration the author got from these historical facts, if not from the 2016 book itself. Despite receiving many awards, like the Hugo, Nebula, and Locus awards!, The Calculating Stars is somewhat of a disappointment to me, because of the highly single-minded perspective,  where everything (related to solving the forecast extinction) seems to happen with a small group of people, because of the confusion between a mathematician and someone who can do complex arithmetics by head, to the near-perfection of the central character, who can also hotwire a car, because of the anachronisms, incl. the prescience that the asteroid crash was going to cause a deadly rise of temperatures when the dinosaur extinction was not yet linked with a similar event, because of a rosy depiction of the World uniting towards racing against the Great Extinction, and, cherry on the pie, because French sentences found throughout the book mostly make no sense as literal translations of English sentences!

“Elle va le faire mais Dieu sait ce qu’elle va parler.” [She’s going to do it but God knows what she’s going to say.]

“Il est l’ordre naturel je pense (…) Il n’y a rien de naturel.” [It’s the natural order of things I think (…) Nothing is natural.]

“Ce ne fut pas une explosion ou nous aurions senti.” [It wasn’t a blast or else we would have felt.]

## Mars attack [live]

Posted in Kids, Mountains, pictures, Travel with tags , , , , , , on February 18, 2021 by xi'an

## and it only gets worse [verbatim]

Posted in Kids, pictures, Travel with tags , , , , , , , , , , , , , , , , , on July 9, 2019 by xi'an

“Increasing export capacity from the Freeport LNG project is critical to spreading freedom gas throughout the world by giving America’s allies a diverse and affordable source of clean energy” M. Menezes, US Secretary of Energy

“NASA should NOT be talking about going to the Moon – We did that 50 years ago. They should be focused on the much bigger things we are doing, including Mars (of which the Moon is a part)” DT,, 7 June

“I just met with the Queen of England (U.K.) [sic], the Prince of Whales [re-sic]” DT, 13 June

“[Sarah Sanders] is going to be leaving the service of her country and she’s going to be going  (…) She’s a very special person, a very, very fine woman, she has been so great, she has such heart, she’s strong but with great, great heart, and I want to thank you for an outstanding job.” DT, 13 June

“…when I asked, ‘How many will die?’ ‘150 people, sir’, was the answer from a General. 10 minutes before the strike I stopped it, not … proportionate to shooting down an unmanned drone.” DT, 21 June

“The reason we have tragedies like that on the border is because that father didn’t wait to go through the asylum process in the legal fashion and decided to cross the river and not only died but his daughter died tragically as well,” K. Cuccinelli, head of US Immigration and Citizenship Services, 28 June

“If Japan is attacked, we will fight World War III. But if we’re attacked, Japan doesn’t have to help us at all. They can watch it on a Sony television.” DT, 24 June

## computational statistics and molecular simulation [18w5023]

Posted in pictures, Statistics, Travel, University life with tags , , , , , , , , , , , , , , , , , , , , , , , on November 14, 2018 by xi'an

On Day 2, Carsten Hartmann used a representation of the log cumulant as solution to a minimisation problem over a collection of importance functions (by the Vonsker-Varadhan principle), with links to X entropy and optimal control, a theme also considered by Alain Dunmus when considering the uncorrected discretised Langevin diffusion with a decreasing sequence of discretisation scale factors (Jordan, Kinderlehrer and Otto) in the spirit of convex regularisation à la Rockafellar. Also representing ULA as an inexact gradient descent algorithm. Murray Pollock (Warwick) presented a new technique called fusion to simulate from products of d densities, as in scalable MCMC (but not only). With an (early) starting and startling remark that when simulating one realisation from each density in the product and waiting for all of them to be equal means simulating from the product, in a strong link to the (A)BC fundamentals. This is of course impractical and Murray proposes to follow d Brownian bridges all ending up in the average of these simulations, constructing an acceptance probability that is computable and validating the output.

The second “hand-on” lecture was given by Gareth Roberts (Warwick) on the many aspects of scaling MCMC algorithms, which started with the famous 0.234 acceptance rate paper in 1996. While I was aware of some of these results (!), the overall picture was impressive, including a notion of complexity I had not seen before. And a last section on PDMPs where Gareth presented very recent on the different scales of convergence of Zigzag and bouncy particle samplers, mostly to the advantage of Zigzag.In the afternoon, Jeremy Heng presented a continuous time version of simulated tempering by adding a drift to the Langevin diffusion with time-varying energy, which must be solution to the Liouville pde $\text{div} \pi_t f = \partial_t \pi_t$. Which connects to a flow transport problem when solving the pde under additional conditions. Unclear to me was the creation of the infinite sequence. This talk was very much at the interface in the spirit of the workshop! (Maybe surprisingly complex when considering the endpoint goal of simulating from a given target.) Jonathan Weare’s talk was about quantum chemistry which translated into finding eigenvalues of an operator. Turning in to a change of basis in a inhumanly large space (10¹⁸⁰ dimensions!). Matt Moore presented the work on Raman spectroscopy he did while a postdoc at Warwick, with an SMC based classification of the peaks of a spectrum (to be used on Mars?) and Alessandra Iacobucci (Dauphine) showed us the unexpected thermal features exhibited by simulations of chains of rotors subjected to both thermal and mechanical forcings, which we never discussed in Dauphine beyond joking on her many batch jobs running on our cluster!

And I remembered today that there is currently and in parallel another BIRS workshop on statistical model selection [and a lot of overlap with our themes] taking place in Banff! With snow already there! Unfair or rather #unfair, as someone much too well-known would whine..! Not that I am in a position to complain about the great conditions here in Oaxaca (except for having to truly worry about stray dogs rather than conceptually about bears makes running more of a challenge, if not the altitude since both places are about the same).

## a sunset no one ever saw

Posted in pictures, Travel with tags , , on March 13, 2016 by xi'an