2017 December 23

originally posted on facebook

Sexual abuse facilitator Cardinal Bernard Law, of the Boston Archdiocese, died two days ago and received honorable funeral rites in the Vatican. “We highly doubt there is a single victim of abuse who will ever receive the same attention, pomp and circumstance by Pope Francis.”



2017 December 12

originally posted on facebook

“The worst result in a simultaneous [chess] exhibition given by a master occurred in 1951, when International Master Robert Wade gave a simultaneous exhibition against 30 Russian schoolboys, aged 14 and under. After 7 hours of play, Wade had lost 20 games and drawn the remaining 10”


2017 November 01

originally posted on facebook

It is illegal in the UK to own a document with information likely to be useful to a terrorist. In 2012, Ruksana Begum was sentenced to one year in jail for having copies of two issues of an al-Qaida magazine on her phone; she argued that she had read the magazine to understand why her brother had decided to become a terrorist (he had been caught several months earlier). In 2016, Abubakar Abubakar was sentenced to 15 months in jail for having a magazine that contained in it instructions on how to avoid getting killed by a drone; these same instructions are available in a Buzzfeed list (translated to English). (link found on Slate Star Codex)


The Guardian



2017 October 31

originally posted on facebook

Today I learned that some of our most used punctuation dates back to ~200 BC, preceding the popularization of lower-case letters or having spaces between words by about 1000 years. The period, comma, and colon have all changed notation slightly since their invention by Aristophanes of Byzantium, but the asterisk has mostly retained its form and meaning (to mark corrections) since its invention by his student Aristarchus (not the famous Aristarchus that suggested that the stars might be other suns, but rather the one known for being a very strict grammarian). “It said that Aristarchus had a remarkable memory and was completely indifferent as to his external appearance.”


2017 October 31

originally posted on facebook

Today is the 500th anniversary of Reformation Day, marking when Martin Luther posted his 95 Theses that eventually led to the protestant reformation. It’s not often you get to celebrate a 500th anniversary, so why not dress up as Martin Luther or 95 theses for halloween this year?


2017 September 04

originally posted on facebook

Two interesting sequences: Gijswijt’s sequence contains every positive integer, but grows so slowly that the first 5 appears around term 10^{10^{23}}. The Golomb sequence grows asymptotically at a rate of \phi^{2 - \phi} n^{\phi - 1} where \phi is the golden ratio. Any other interesting contexts in which the golden ratio appears raised to the power of itself?



2017 August 10

originally posted on facebook

Near Xenon’s critical point at 58 atm and 17 C, Xenon gas has a density of 1100 kg / m^3, greater than liquid water at those conditions. So what happens if you try to float liquid water on Xenon gas at those conditions? You get a solid.

(Formation of xenon hydrate at 4m10s; most interesting part is at end of video.)


2017 July 13

originally posted on facebook

In all the talk about Trump Jr’s soliciting Russian help, there is another story I have not seen discussed: Peter Smith, Republican operative close to Flynn and member of shell company “KLS research” set up by the Trump campaign to conduct opposition research without being subject to campaign reporting laws, openly claims to have tried (in September 2016) to obtain Clinton’s emails from a source he thought may have been representing the Russian government. The story is somewhat circumstantial and doesn’t come together as neatly as Trump Jr directly admitting to conspiracy, but it may be very pertinent.

Peter Smith committed suicide in May at 81, citing declining health.





2017 June 01

originally posted on facebook

Today I learned that there is a layer of sodium at an altitude of ~100 km in the Earth’s atmosphere caused by meteors.


2017 May 24

originally posted on facebook

In yesterday’s press briefing, White House OMB director Mick Mulvaney uses the word “compassion” five times to refer to the proposed cuts to food stamps and social security disability.

“We’re no longer going to measure compassion by the number of programs or the number of people on those programs, but by the number of people we help get off of those programs.” -Mulvaney


2017 May 14

originally posted on facebook

“They lifted half a city block […] and an estimated all in weight including hanging sidewalks of thirty five thousand tons. Businesses operating out of these premises were not closed down for the lifting; […] One patron was puzzled to note that the front steps leading from the street into the hotel were becoming steeper every day and that when he checked out, the windows were several feet above his head, whereas before they had been at eye level. […] the practice of putting the old multi-story, intact and furnished wooden buildings – sometimes entire rows of them en bloc – on rollers and moving them to the outskirts of town or to the suburbs was so common as to be considered nothing more than routine traffic.”


2017 May 12

originally posted on facebook

Seen in a math textbook: “This is all one needs to check that T(x) is metrically transitive, and this is entirely trivial.1

Footnote: “1Here I was carried away by a burst of inexplicable optimism. While the fact is intuitively obvious the proof is, alas, not.”

2017 May 05

originally posted on facebook

“we would estimate that stripping insurance from 24 million people would produce an estimated 24,000 additional deaths annually. That is 40% more than the sum total of all murders”

The Guardian

2017 April 20

originally posted on facebook

In classical electromagnetism, we usually think of the electric fields and magnetic fields as the fundamental objects of study, in the sense that if you know the fields at the location of interest, you know the forces, and can fully describe any physical behavior of the system.

It turns out, as I have just learned, this is not quite true; as a specific example, consider performing the double-slit experiment with electrons being thrown at a barrier with two slits. If an ideal solenoid (which has a nonzero magnetic field contained within it) is placed between the slits, then the electron will experience a different phase shift depending on which of the slits it passes through, the amount depending on the strength of the solenoid, despite the fact that in either case the electron only passes through a region of space with zero EM field.

The resolution is that in QED the fundamental object in EM is not the fields but their potential (the electric field being the gradient of the electric potential, and the magnetic field being the curl of the magnetic potential). Changes in the EM potential can be observed even if there is no change in the EM field at the location of the test particle.

Alternatively, one can retain the EM field as a fundamental object if you abandon the principle of locality, and permit a test particle to be affected by the EM field in far away locations. This is because if we know the EM field everywhere we can always just integrate it to obtain the EM potential (up to various constants, which are physically irrelevant).

The first article below has a quite clear explanation of this:



2017 March 21

originally posted on facebook

Today I learned that an acre-inch per hour is almost exactly equal to a cubic foot per second. Who said US units are hard?

2017 March 07

originally posted on facebook

Until today (or maybe late yesterday), whitehouse.gov listed Obama as the current president at the following link (it now lists Trump). I’ve been checking everyday since this was brought to my attention by Joshua Z


2017 January 29

originally posted on facebook

“Republicans don’t look at polls and think”we need to moderate our platform because Americans don’t support starving the poor to death, and we’ll get negative media coverage“; they work hard over the course of many years to shape public opinion until it says what they say.” -Michael Kinnucan

I see the Republicans’ electoral success as founded primarily on their relentless propaganda machine (although they had to divorce themselves from reality to build it). The median voter theorem only works if the voters actually know what the parties’ positions are, and not just what they were told they are by the Republicans.

Republicans will always have an advantage at messaging since their messaging is unconstrained by bearing any relationship to truth or helping people, but Michael is right that the Democrats still can learn a lot from them about messaging even without compromising important principles.

Another thing Democratic politicians (re., e.g., congressional votes) and progressive voters (re. elections) could learn from Republicans is a little game theory, and the importance of party loyalty in a first-past-the-post system. Which is to say, feel free to argue about principles and ideals all you like so long as when the vote comes up, you vote, and you vote to win, and not vote to feel good about yourself.


2017 January 20

originally posted on facebook

"Lemma 0.3. Let S be a Scheme. Let X be a scheme and X is an affine open covering. Let \mathcal U \subset \mathcal X be a canonical and locally of finite type. Let X be a scheme. Let X be a scheme which is equal to the formal complex.

The following to the construction of the lemma follows.

Let X be a scheme. Let X be a scheme covering. Let

b : X \to Y' \to Y \to Y \to Y' \times_X Y \to X

be a morphism of algebraic spaces over S and Y."

An example of computer-generated text trained on an algebraic geometry textbook, which include a hilariously messed-up attempt at drawing a commutative diagram. See also examples of computer-generated Shakespeare, Wikipedia articles, and C code:


Someone else took the same software and used it to generate novel folk music. Check out the traditional folk song Drike in the Sterthe Cunter House.


2017 January 12

originally posted on facebook

“Extrapolating from present information, …probably… it will be shown in the future that average American adults experience a variety of significant physiological and intellectual dysfunctions caused by long-term chronic lead insult to their bodies and minds which results from excess exposures to industrial lead that are five hundred-fold above natural levels of lead exposure, and that such dysfunctions on this massive scale may have significantly influenced the course of American history.” -Clair Patterson, 1980. Patterson was responsible for conclusively demonstrating the dangers of leaded gasoline, although as a side project for determining the age of the Earth.

I found that quote on this site, which includes fearsome maps of lead contamination in air and soil of many major cities. In particular the map of lead poisoning in Chicago is almost exactly a racial map, with major black communities having close to 100% of children with “concerning” levels of lead (5 ug/dL and up). Soils in downtown areas frequently reach 0.1% lead or higher.


2017 January 07

originally posted on facebook

With the worldwide banning of leaded gasoline and the banning of leaded paint in the US and EU, I was under the impression that chronic environmental exposure to lead was largely a thing of the past. This is mostly true in the US, where blood lead levels have plummeted since the 70s, with the levels observed in Flint, MI today being substantially below the average for children in the 60s and 70s.

So I was disturbed to learn today that exposure to lead still kills over 100 000 people per year, and is blamed for intellectual disability in 600 000 children per year. Leaded paint is commonly used in India and China today, and in India lead is often found in spices and sometimes added to medicine or ceremonial powders. Tests of three samples of sindoor (a cosmetic) purchased in Boston and imported from India found all to be 50% lead by weight.


2017 January 01

originally posted on facebook

I think 2016 will be (and should be) remembered for two things: the putative discovery of the 9th planet in the solar system, and the announcement of the first observation of gravitational waves.

YouTube This video gives a brief introduction to the discovery of gravitational waves, although it omits one important point, which is that EM astronomy cannot directly observe anything older than the CMBR (the first 380 000 years after the Big Bang) whereas GW astronomy has the potential of making observations back to the first seconds.

(Also the peak power output of the black hole merger was 50 times the power output of the visible universe, not 10 times as stated in the video. The main uncertainty of this figure is due to the uncertainty of the power of the universe, not of the black hole merger.)

A sample of notable scientific events in 2016 include the discovery of the 49th known Mersenne prime 2^74207281 - 1, the first vertical powered landing of a suborbital rocket on a floating platform, the discovery of flowing water on present-day Mars, the first landing on a comet, and the first high quality scientific observations of Pluto.


In other astronomy news, the closest known star to the Sun had its name standardized to Proxima Centauri in August (previously Alpha Centauri C), and a planet in its habitable zone was discovered just 3 days later. It weighs 1.3 Earth masses. The star itself was discovered (and its current name proposed) in 1915.

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