Thursday, September 4, 2014

How Light and Sound are Different

The other day I started doing the Doppler shift as a relativity problem. It starts off looking a lot like the Doppler shift for ordinary sound in air. I had Alice sending a series of sound/light pulses to a train travelling at 4/5 the speed of sound/light; and I had Bob on the back of the train with a mirror reflecting the sound/light back to Alice. It's not too hard to calculate that if Alices pulses are 1 microsecond apart, then when they come back to Alice they are 9 microseconds apart, for a Doppler shift of 900%. You can see it easily from the picture below. The calculation is correct for light, and it's correct for sound:

What gets funny if we asked how much Doppler shift Bob sees. It's not hard to do the calucation for sound in air. We just drop vertical lines from Bob's pulse detection points down to the time axis. It's not hard to see that Bob detects the pulses 5 microseconds apart, for a Doppler shift of 500%:


Here's the thing: Bob is sending out pulses 5 microseconds apart, and Alice is measuring them 9 microseconds apart. So Alice's Doppler Shift is 180%. That's not the same as Bob's. So by analyzing who has a greater doppler shift, they can figure out that Alice is stationary and Bob must be moving.

And that's not how relativity works. In relativity we're not allowed to distinguish the stationary from the moving observer, so both Alice and Bob have to measure the same doppler shift. It's almost impossible to see how they can do that...unless we realize that time is moving slower for Bob than for Alice.

The total doppler for the reflected pulses is 900%. And the only way to make it the same for both observers is for them both to see 300%. Bob sees the pulses 3 microseconds apart, and Alice sees them 9 microseconds apart.

We did the caluclation for the special case of the train going at 4/5 the speed of light. But if we let the speed vary from 0 to 100%, and trace the contour defined by the equal-interval ticks, we will find that they are the hyperbolas defined by the equation x^2 - t^2 = constant:



Tuesday, September 2, 2014

The Doppler Shift in Relativity

It's been quite a while since I've posted any new physics, but I had a visit on the weekend from an old physics buddy from univeristy days. Richard is teaching at Waterloo these days, and relativity is his thing. I've mentioned once or twice that it's not really my territory, but last year I thought I did a pretty nice series on how to do those first-year compound velocity problems with pictures. I didn't assume any formulas except for the fact that x^2 - t^2 is invariant (the relativistic Law of Pythagoras.) You can see what I wrote here. Near the bottom of the page you can see how hyperbolas on the x-t diagram are the same "distance" from the origin. So someone moving along the orange line counts of his seconds "one, two, three..." accorcing to when he intersects those hyperbolas:


Well, on the weekend Richard and I were talking physics, and he told me about a problem he gave his students to calculate the doppler shift in relativity. He wanted them to do it without using the formula, just deriving it from basic principles. Naturally I wanted to try it for myself - and without assuming anything about x^2-t^2. I think I got it right, and as a consequence, basically derived the fact that x^2-t^2 is invariant. Here is what I did.

Now, what you normally do is have an observer on the ground (Alice) and an observer in the train (Bob). Alice stands on the tracks after the train has passed and broadcasts a radio signal to Bob, say 900 kHz. Bob measures the frequency and finds it is slower than what Alice sent out. This is normal: it's just the same way sound works. If Alice blows a whistle at 900 hz, Bob hears it at a lower pitch. If Bob blows a whistle, Alice hears the pitch change from high to low as the train passes by her. That's how sound works, and that's how light works. Either way, the picture looks like this:

The orange line is the moving train (which I'm going to take as going 4/5 the speed of sound (or light) in this picture, and the blue lines represent the "pulses" passing between the two observers. You can think of them as pulses or you can think of them as wavefronts, where I've drawn the waves in purple. I've done something a little bit odd: instead of Alice blowing one whistle and Bob blowing another one, I have Bob holding up a mirror so that Alices waves get reflected right back to her. The sound is reflected back at a lower pitch, and so is the light.

It's not hard to do the calculation for Alice. It's not so hard to see (from the basic geometry) that if she blows a whistle at 900 Hz, the echo that relfects back reaches her ear at 100 Hz. And it's the same for light waves: if she radios Bob at 900 kHz,  it comes back at 100 kHz.


(It's actually a little more natural to work with periods instead of frequency. If alice sends out pulses (of sound or light) one microsecond apart, they come back to her nine microseconds apart.)

But where it gets interesting is when we consider what Bob hears. For Alice, it's all the same if she's sending out light pulses or sound pulses. But for Bob it makes a difference, and there are big imlications that flow from that difference. That's what we'll talk about when I return.

Wednesday, July 16, 2014

Sex and Yiddish



This is one of my favorite Jewish Post articles ever.

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Last year I mentioned the legend whereby the Eskimos supposedly have dozens of words for “snow”. Whether or not this is strictly true, it illustrates the tendency of a language to develop in areas which are important to the culture of its speakers. In this regard, one has to wonder if any language has a more fully developed (or faster growing) vocabulary for matters sexual than our own English language. 

One of the newest entries to the extended sexual lexicon is “twerking”, a dance move which rocketed to prominence with the wrecking-ball video of Miley Cyrus. I’m not sure if the word is totally brand-new, but the dance move surely goes back a good few years. Myself, I give Christina Aguilera credit for permanently imprinting the “twerk” in my consciousness with her 2002  video “Dirty”. If you’re a man, you know what I’m talking about.

Of course there are any number of innovative words used to describe women as sexual objects, from the derogatory skanks and cougars to the self-consciously neutral posslq, but I think my favorite has to be the milf. I’ll never forget in Season 3 of “The Apprentice” when Donald Trump told TanaGoertz, a popular 40-ish contestant from the midwest, that people were saying she was a milf. “Do you know what a milf is?” he asked her. “Yes”, she answered, “it’s a mother I’d like to fool around with.” Yes Tana, you certainly were, with your cornfed Iowa wholesomeness. But I digress. 

If sexuality is front and center in our North American culture, then what more can we expect from the Yiddish language than the paucity of expressions for such things? I’m not even totally sure how I would say “girlfriend” in Yiddish…there is khaverte, which in North America would surely be understood as girlfriend by analogy with the English usage, but I don’t think that was the connotation in the old country. (It should be admitted that Yiddish is not alone in having difficulty here…even in English, it is not so easy to distinguish the case of a simple female friend, never mind the awkwardness of an unmarried elderly gentleman having to introduce his female companion as a “girlfriend”.)

At the other extreme of the relationship spectrum, we have the prostitute. Yiddish eschews the German hure in favor of either the Hebrew zoyne or the Slavic kurve (Polish kurwa). I don’t have a very good feel for the distinction in nuance between these, but I think it would have been consistent with the natural ironic bent of the language to apply the Hebrew term to the Gentile prostitute and vice versa.
And finally, in between the girlfriend and the prostitute, we have the mistress. In Yiddish she is the kokhanka, borrowed from the Polish. Once again, it is somewhat beyond my expertise to determine if the meanings correspond with exactitude. Even in English, we have to ask…just what is a mistress? A married man who keeps an apartment for a lover on the side surely has a mistress. But what if he just sneaks around with her on a regular basis? Is she his mistress or just his girlfriend? I’m not sure. I’m not sure if a single man in North America can be said to have a mistress (even whether or not he pays her) but I think in the old country he could have had a kokhanka….probably because there’s nothing illicit nowadays in sleeping with your unmarried girlfriend, as there would have been in der alter heim.  

In Mein Zikhroynos, the memoir of Yekhezkel Kotik, the author remembers from his childhood (around 1860) the jealousy of the poor Orthodox priest in his village, comparing his lot with that of the local Catholic priest, whose lifestyle was lavishly supported by the wealthy Polish squires. Hear what the Orthodox galakh though of his counterpart’s four beautiful sisters, who lived together with him in luxury:

“Nur der ârimer Russischer galakh, welcher flegt platzen far kinah (envy) vun dem reichen luxus-leben vun dem Kathòlischen galakh, hât var seine pauerim, die poretzische leib-knecht (the squire’s serfs) geschwòren, as die schöene Fräuleins seinen gâr nischt seine schwester, séi seinen ihm wild-fremde (total strangers), kokhankes seinen séi ihm, nur asõ wie a Kathõlischer galakh tor doch kein weib nischt hâben, hât er araus-gelâsen a shem (let it be known) as séi seinen schwester. Men mus moydah sein (one must admit) as der ârimer Pravoslavner galakh hât gehat recht: séi seinen wirklich geween kokhankes, un nischt seine schwester.”

Yes, it was a very different world. No one was twerking on MTV, and a woman was (sadly) old at forty, not milfy in the slightest. And yet some things were the same…

Thursday, July 10, 2014

John Q. Public



A few weeks ago I wrote about the word öffentlechkeit, which I claimed was a mistranslation of the American concept of “the public”. Yes, as an adjective öffentlech means “open” in the sense of “public”. And –keit changes an adjective to a noun. But surely the noun which results from adding –keit to öffentlech should have more to do with the attribute of something being in the public domain than a literal translation of the phrase “the public” in the sense of the man in the street.

I took up this discussion with a German Language forum on the internet. True, the nuance in Yiddish will sometimes be different from the equivalent in German, but it’s a good place to start. Except I got shot down in flames. It turns out that in German, according to several very reliable correspondents, die Öffentlichkeit is exactly “the public” in the same sense we  use it in English. To be sure, there is are secondary meaning which carry the connotation of  either “the public discourse” or the forum where that discourse takes place, but in common usage it is simply “the public”.

I still think that regardless of the facts on the ground, I should have won that argument. The English “public” comes from the Latin publicus, which was literally the public. The concept of the public as a body of citizenry distinct from the rulership or the slave class was an novel idea of the Roman system, so it is only fitting that the word has come down to us in that sense today. Its use as an adjective is clearly derivative from the noun…something is “public knowledge” because it is open to the public. Whereas in German you start with the adjective/adverb “openly”, tack on an ending, and it becomes…the public? It doesn’t make sense.

Oddly enough, in German (and Yiddish) das publikum is a perfectly good word, but it’s used to describe the audience, as in a theater performance or a lecture. (I don’t think it would be used for a sporting event.) In that sense it’s very similar to Yiddish der oylam, except that the Yiddish word also serves for the congregation in a synagogue, and I don’t think das Publikum would be used for churchgoers.

We still have one more noteworthy expression for “the public” in Yiddish: die gass, literally “the street” from the German Gasse, small lane. Oddly enough the German’s have Strassen und Gassen, big and small streets, but in Yiddish we have only gassen: our highway is die chaussée. No, that’s not evidence that Yiddish had its roots in Old France…like cauchemar (nightmare), trottoir (sidewalk), and even crêpelach (!) these French words came to us via upper-class Russian society. Not to be outdone by the Germans, mind you, we can still rhyme “streets and roads”; but instead of Strassen und Gassen, we have weggen un steggen.

What is interesting about die gass is that there was really no such thing as “the public” in the old country. There was literally no occasion when you would speak of “the public” as comprising both Jews and Gentiles; you could talk about die Yiddische Gass or die Goysiche Gass, but never just die Gass. There was no Ivan Q. Public in Minsk or Vilna; there were Jews and Christians, Catholics and pravoslavne (Russian Orthodox), serfs and landholders, Poles and Ukrainians…but no coherent “public”. So the Western European concept of die Öffentlichkeit would have been pretty much a non-starter.

Monday, June 30, 2014

The Odessa File

From my Jewish Post series:

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As I get older, I find I have less patience for reading fiction. I don’t feel entirely comfortable knowing that my emotions are being manipulated with made-up stuff. Oh, I still enjoy a good read, if perhaps not quite as much any more. But I haven’t forgotten the feeling of heart-pounding, cold-sweating excitement I used to get from a good thriller/mystery. The Odessa File by John Forsythe was one such book. Maybe you saw the movie starring Jon Voight as a young German journalist named Peter Miller who makes it his business to track down a notorious S.S. commandant named Eduard Roschmann (a true historical figure by the way), also known as the Butcher of Riga. 

I especially remember the thrilling confrontation, near the very end of the book, where Miller confronts Roschmann with the photograph of a man he had murdered. That man was….Miller’s father!…a Wermacht officer whom, in the last days of the war, Roschmann had shot in the back in order commandeer  a ship to facilitate his own escape the advancing Russian army. Of course, everyone had assumed that Miller was an idealist who was motivated by outrage at the Holocaust. “So…it wasn’t the Jews after all?” asks an astonished Roschmann? “Oh, I felt sorry for the Jews all right,” answers Miller. “But not that sorry.”

To be perfectly honest, I also remember feeling a distinct tinge of resentment at Miller…that he placed a higher priority on avenging the personal murder of his father over the much more enormous crime of what Roschmann had done to the Jews. Oh, it was a brilliant dramatic twist, no doubt…but did Forsythe have to give the Jewish tragedy a back seat to Miller’s personal family tragedy? It bothered me more than a little.

But that isn’t why I bring up the book today. No, I wanted to tell my our readers that I’ve started buying free-run eggs. Not all the time, but fairly often. Not when the regular eggs go on sale of course…I can’t pass up the chance to stock up at $2.00 a dozen…but when they’re not on sale, if it only costs 50 cents more to buy free run, I’m down with that. The fact is, I feel sorry for the poor little chickens, cooped up in those tiny cages, forced to sit in one place their whole life. Not that sorry, but sorry enough to cough up an extra 50 cents now and then. (And for some reason, every time I do, I think of Jon Voigt.)

Which brings me to the real point of today’s article: cruelty to animals. To what extent are we, as human beings, entitled to bring suffering to the animals we eat, simply for the sake of a slightly cheaper cut of meat? Don’t we have a duty to pay just a little more at the meat counter if it means that an innocent animal might have enjoyed a better quality of life?

This is not a joke. You should watch some of the documentary footage available of the appalling suffering in large-scale commercial pig barns. It is especially heart-wrenching when you see how playful and spirited pigs can be when allowed their freedom. Yes, in the end they are all going to be slaughtered for meat…but aren’t they entitled to a decent life up to that point?

I know what your thinking…what does this have to do with the Jews? Well, I’m wondering what would happen if we could find 100 orthodox rabbis to come forward and say that for the sake of tzaar bale-khayim, that they were going to sit down to a Sabbath meal of free-run pork.

What in the world would be the point of that, I hear you ask? I’m thinking it would send a pretty powerful message to the rest of the world. After all, we are famous for regarding khazer-fleisch as an abomination. Wouldn’t it say something to the world if all those rabbis were willing to break one of our most sacred commandments in order to encourage more humane treatment of animals?
For two thousand years our people have distinguished themselves by the extraordinary lenghts to which we have gone to follow God’s laws to the letter, even in the face of the greatest difficulties. Many of our religious leaders have preached that if only by reaching perfection in our obedience to those commandments can we hasten or bring about the coming of the Messiah. Now, I can’t pretend that I am personally a believer, but what if…what if  the real reason we were given those laws was to test us, not to see how obedient we could be, but to see if we had the courage and the clarity of vision to understand when we ought to break those rules instead of following them?

It’s something to think about.

Friday, June 13, 2014

Öffentlichkeit

From my Jewish Post series:

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A few weeks ago I wrote an article comparing the quality of Yiddish in two leading newspapers…the Allgemeiner Journal, and the Vorwärts (also known as the “Forverts”). The latter paper recently shut down its print version, but still maintains a vigorous internet presence. I was at the downtown library today, where they still stock the Allgemeiner Journal, and I read a few articles.
The lead article was about the release of 26 long-term Palestinian prisoners, apparently under the prodding of Secretary of State John Kerry, as part of a good-will gesture to the Palestinian negotiators. What made this special was that these were identified as prisoners with “blood on their hands”, which provoked considerable outrage among the Israeli public. I was also outraged although perhaps only mildly so. My feelings had less to do with the political issues involved than with the Yiddish word the writer had chosen to describe the Israeli “public”: he called it the öffentlechkeit. Surely this was a clumsy adaptation derived by working backwards from the English?

The root of the word is clearly the same as the English “open”; so the adverb “öffentlech” is uncontroversial in its meaning of “out in the open”, or more simply “publicly”. Now, in Yiddish, adverbs are not always so clearly distinguished from adjectives; so the same word is aguably translateable as the adjective “public”. (At least Weinreich assigns it double duty; and who am I to argue with Weinreich?) The question is: does adding the noun ending –keit transform the adjective to the noun we understand in English as “the public”? I don’t think so.

Yet going down the column of entries, I see that Weinreich does indeed list die öffentlechkeit as a noun, and he translates it as “public”. Not the public, just public.Well, I gave him a pass on the adjective, but now I’m not so sure I want to let him off the hook that easily. So I check in Harkavey. Sure enough, it’s there, but Harkavey defines it as publicity. That’s quite different. I’m not sure I find it convincing in its Madison Avenue sense, and perhaps that’s not what it meant to Harkavey in 1908. I find it more convincing as publicness, as in the “publicness” of Rob Ford’s disgrace over the tapes. That I’m willing to buy.

But just to make sure, I run a google search on it. There is a lot of transcribed Yiddish on the internet, especially in places like the Mendele archives, where you can find authentic Yiddish written by highly literate speakers. So I typed in “efentlekhkayt”, using the standard YIVO phonetics espoused by the professor types. Sure enough, I got a hit.

The word appears in the writings of Warsaw Ghetto diarist/historian Emanuel Ringelblum; writing about the despair of the Ghetto at the failure of the Poles to bring the Jewish tragedy to the attention of the outside world, he wrote in 1942:

“We were angry at the Polish community [efentlekhkayt] and at those in contact with the Polish government because there were no transmissions about the murder of the Polish Jews…”

Surely if Ringelblum used the word to mean “community”, that is consistent with the use of “public” to which I objected in the Allgemeinter Journal. Perhaps I was wrong.

Or was I? Just what did Ringelblum mean by that word? He wrote in Yiddish, not English…the English translation of “community” was provided by one Samuel Kassow,  author of the book Who Will Write Our History where the quoted passage appears. What then are Kassow’s credentials as a translator? And why, in the midst of a long quoted passage translated from Yiddish, does he single out one word to indicate the Yiddish original? Perhaps he himself was not so sure of the intended nuance. Even Harkavey’s “publicity”, in its admittedly dubious Madison-Avenue sense, arguably works just as well in this passage. Was Ringelblum angry at the Polish public, or at the Polish publicity which downplayed the Jewish tragedy? It’s not so obvious.

Kassow’s credentials, by the way, check out. He is an American professor and author of books on Ashekenazi Jewish history, born in a DP camp in Germany in 1946. So I’m guessing his Yiddish is better than mine. Still, when it comes to that one word in that one passage…what does he know that I don’t?

We still haven’t exhausted all avenues of research. In Yiddish, when in doubt…look to the Kraut. And what a treasure-trove of information we find when we google Öffentlichkeit (the Germans of course capitalize their nouns.) It is indeed a word in German, in fact a highly nuanced concept so intricate that it merits its own lengthy article in the German Wikipedia.

If my German is to be trusted, then the concept of Öffentlichkeit describes the realm of social and political discourse, the public arena in which ideas and ideologies are hammered out and debated. If Ringelblum was using the word in this sense, then he was deploring the miniscule place the Jewish tragedy occupied in the general Polish discourse.

I have more to say about this but I think I’ve hit my 900-word limit. So, with Bernie’s permission, we’ll continue this discussion when we return. Unless he tells me he wants something a bit lighter, which I must admit is a distinct possibility…