Saturday, February 25, 2017

Teaching Physics

What we know about physics can be summarized in very compact form. Classical electrodynamics is a subject that remains of immense practical importance as well as foundational for the modern field theories of particle physics and relativity. The equations that describe it can occupy less than a fourth of one of these lines of text. See, e.g., the tensor and differential form versions of Maxwell's equations in this Wikipedia article.

Chad Orzel recently wrote a post on teaching so-called Modern Physics, which is conveniently summarized as the physics discovered between 1899 and 1950. In particular he makes the case for teaching the history of the discoveries. His point is that you can learn a lot from understanding how the laws of physics were discovered and why we believe them - but read Chad's version, he's a good writer.

The alternative method, and it's also used a lot in physics, is to just write down the equations and then develop the mathematical techniques one can use to deduce their consequences. If one picks up a graduate level book in classical electrodynamics (e.g., Jackson's Classical Electrodynamics) that's mostly the approach you will get. In the US, anyway, physics students tend to get a three-layer approach to electricity and magnetism, starting with experimental results and formulation in calculus of integral equations in a General Physics course, with an intermediate layer from a book like Griffiths and Jackson as a sort of finale.

The historical approach can be instructive, but it can also be slow to recapitulate all the steps and there is a mountain of mathematical technique to learn.

Friday, February 24, 2017

Whose Jobs do the Robots Get?

Paul Krugman:

Izabella Kaminska has a thought-provoking piece on the real effects of technology on wages, in which she argues that much recent innovation, instead of displacing manual workers, has displaced high-paying skilled jobs. As it happens, I sort of predicted this 20 years ago, in a piece written for the Times magazine’s 100th anniversary (authors were asked to write as if it was 2096, and they were looking back.)

I argued then that menial work dealing with the physical world – gardeners, maids, nurses – would survive even as quite a few jobs that used to require college disappeared. As it turns out, big data has led to more progress in something that looks like artificial intelligence than I expected — self-driving cars are much closer to reality than I would have thought, and maybe gardening robots and post-Roomba robot cleaners will follow.

Lawyers, pathologists, translators are all getting heavily hit, but I suspect that robotics is getting much closer to being an equal unemployment opportunity. Many medium skill jobs like truck and taxi driver have less than ten years left, and fast food employees could well decimated soon too.

Monday, February 20, 2017


Temperatures in the high Arctic are finally nearly down to normal after having spent the previous three months 5 C or more above normal. There are still almost two months of hard winter up there so Santa may not want to break out his swim suit for a bit.

In the Antarctic, sea ice extent is at record lows for the satellite era, while the Arctic is nearing sea ice max at levels barely above record lows for the date.

Advice for the FP

As early as the mid-third century BC, the Indian emperor Ashoka erected large stone pillars or signboards in Kandahar, Afghanistan, as well as in other cities, on which he displayed edicts on how good behavior or the Buddhists’ dharma could be spread. He counseled his subjects that “piety and self-control [exist] in all philosophical schools. But the most self-possessed are [those people] who are the masters of their tongues. They neither praise themselves nor belittle their fellows in any respect, which is a vain thing to do. … The correct thing is to respect one another and to accept the lessons of each other. Those who do this enlarge their knowledge by sharing what others know.”66

Starr, S. Frederick. Lost Enlightenment: Central Asia's Golden Age from the Arab Conquest to Tamerlane (p. 81). Princeton University Press. Kindle Edition.

Of course the fool is immune to advice.

New NSC Chief

H. R. McMaster is the real deal.

He's a soldier scholar who is used to telling truths to power.

Sunday, February 19, 2017


A Chinese visitor to Samarkand in the century before the Arab invasion wrote in his notes the following observation on young people there: “All the inhabitants [of Samarkand] are brought up to be traders. When a young boy reaches the age of five they begin to teach him to read, and when he is able to read they make him study business.”1 Another Chinese visitor, equally astonished, observed that young Central Asian men were not allowed to participate in trading trips abroad until they were twenty, prior to which time they were expected to be absorbed in study and training.2

These observant contemporaries enable us to understand something very important about the lost world of Central Asia before the Arab conquest: the high level of literacy that prevailed there. The mass destruction of books and documents carried out by the Arabs leaves us particularly dependent on the reports of outsiders like these.

Starr, S. Frederick. Lost Enlightenment: Central Asia's Golden Age from the Arab Conquest to Tamerlane (p. 62). Princeton University Press. Kindle Edition.


Eleven hundred years ago, Central Asia was the intellectual and cultural center of the world. It's cities were the wealthiest in the world, and mathematics, astronomy, architecture, art and literature had a golden age of enlightenment. No city was richer than Balkh, in what is now Afghanistan.

To approach Balkh today is a sad experience. Where ancient visitors reported on vineyards, citrus groves, and fields of sugar cane, there is only sagebrush and dust, relieved by an occasional hollyhock in the lower-lying areas. Similarly, far to the north in Central Asia, the vast reaches of Khwarazm in Uzbekistan and Dehistan in Turkmenistan were once alive with castles surrounded by farmland but are today bleak deserts, utterly devoid of plant life.

Starr, S. Frederick. Lost Enlightenment: Central Asia's Golden Age from the Arab Conquest to Tamerlane (p. 35). Princeton University Press. Kindle Edition.

The Balkh river, which once supported cargo boats to and from the Oxus and Aral Sea is now dry.

What happened is a now familiar story of ecological destruction. It started in the Bronze Age with deforestation to build and feed foundries, and with sheep and goats which can chew grass short enough to kill it. The final catastrophe, though, came with the reckless Soviet exploitation of irrigation to grow cotton. This turned the Aral Sea into a vast salt flat, and was only slightly less devastating to the Caspian.

Saturday, February 18, 2017

Opinions on the Shape of the Earth Differ...

Kyrie Irving:

Good thing he has a very high basketball IQ.

Or he could be having a bit of fun with us. Or maybe has never looked out of an airplane window.

Friday, February 17, 2017

One State Solutions

Our FP indicates that the so-called two-state Israel Palestine conflict is passe. So what does that leave?

Apartheid, with Palestinians as a permanent underclass.

Genocide, with Israel becoming an outlaw state.

One person, one vote, with Israel likely to become an Islamic state.

Anybody want to guess what's most likely, or suggest a better alternative?

My personal favorite is that the Palestinians convert en masse to Southern Baptists. This would pose a pretty puzzle for Israel.

Which Enemy?

A recurring theme in the history of fallen nations is that some factions in a local dispute see advantage in allying with an aggressive outsider against their local enemies. In this fashion a few British adventurers conquered India, Cortez conquered the Aztecs, Rome invaded Britain, and Persia subdued Babylon.

So too today, the Republican Party of the United States seems prepared to tolerate massive interference in our electoral process and other corrupt practices in the hope of enacting the unpopular wishes of their plutocratic masters. Paul Krugman today:

The story so far: A foreign dictator intervened on behalf of a U.S. presidential candidate — and that candidate won. Close associates of the new president were in contact with the dictator’s espionage officials during the campaign, and his national security adviser was forced out over improper calls to that country’s ambassador — but not until the press reported it; the president learned about his actions weeks earlier, but took no action.

Meanwhile, the president seems oddly solicitous of the dictator’s interests, and rumors swirl about his personal financial connections to the country in question. Is there anything to those rumors? Nobody knows, in part because the president refuses to release his tax returns.

Maybe there’s nothing wrong here, and it’s all perfectly innocent. But if it’s not innocent, it’s very bad indeed. So what do Republicans in Congress, who have the power to investigate the situation, believe should be done?


Paul Ryan, the speaker of the House, says that Michael Flynn’s conversations with the Russian ambassador were “entirely appropriate.”

Devin Nunes, the chairman of the House Intelligence Committee, angrily dismissed calls for a select committee to investigate contacts during the campaign: “There is absolutely not going to be one.”

Jason Chaffetz, the chairman of the House oversight committee — who hounded Hillary Clinton endlessly over Benghazi — declared that the “situation has taken care of itself.”

Just the other day Republicans were hot in pursuit of potential scandal, and posed as ultrapatriots. Now they’re indifferent to actual subversion and the real possibility that we are being governed by people who take their cues from Moscow. Why?

Well, Senator Rand Paul explained it all: “We’ll never even get started with doing the things we need to do, like repealing Obamacare, if we’re spending our whole time having Republicans investigate Republicans.” Does anyone doubt that he was speaking for his whole party?

The point is that you can’t understand the mess we’re in without appreciating not just the potential corruption of the president, but the unmistakable corruption of his party — a party so intent on cutting taxes for the wealthy, deregulating banks and polluters and dismantling social programs that accepting foreign subversion is, apparently, a small price to pay.

To B* or not to B

* Blog, that is.

One reason that I've been increasing reluctant to write anything on the blog is the near certainty that anything I write will be met with a mostly off topic, inane, or otherwise annoying rejoinder from a notorious internet troll. I hate to suppress dissent, but I also dislike the idea of my blog becoming a forum for Exxon, the FSB, or general crackpottery. Comments?

Thursday, February 16, 2017

Saturday, February 11, 2017

Tie-ing Times

The NYT has a piece today on our President's seeming inability to properly tie a tie.

Which reminded me of a time when I was in a play at the local university. The costumer asked me if I knew how to tie a tie for my character's costume (I was about 50 at the time), so I asked what knot she wanted, listing a few of the options. Her reply: "OK, I forgot that you were a real person."

I'm not sure that Trump is a real person. At least I hope not.