Relatively Pleasant

By cjohnson | April 26, 2006 9:10 pm

It is that time of year again. Because I am insane, I am teaching -by choice- two classes this semester. One of them is quite small, having 12 students, the other is not. The small class is my electricity and magnetism class. With a class this small, it is nice sometimes to have a change of scenery, and -if the material can handle it- I show up one sunny Spring day (after the hard slog through rainy Winter days) and declare that we are going outside to sit under a tree. There are several lovely spaces on the USC campus perfectly suited to this, and so we go outside. Last year, when I first had the idea for doing this, eventually I thought to buy a little portable whiteboard in case I need to write or draw something. (I discovered that the board fits perfectly into my Brompton‘s front carrier bag, sticking pleasantly out of the top as I cycle along!)

It’s just a perfect setup actually, since this time of year usually coincides with the last part of the class where we are doing Special Relativity. I can think of few physics topics which are better suited to sitting outside and discussing under a tree -with a few diagrams and equations- than the classic thought experiments of Special Relativity. Here’s everyone in the class (except Chris Cantwell, who unusually could not make it this time), and also the whiteboard, my coffee cup, and the Brompton (of course): USC electromagnetism class
(L to R: Michael Crampon, Jeff Pennington, Michael Johnson, Douglas Mason, Omar Hussein, Aleksandr Rodin, Amanda Fournier, Christopher Winterowd, Christopher Palmer, Justin Seymour, Matthew Recker.)

You can see, if you look closely, the last remnants of the moment of confusion that appeared on their faces from just being told that a vector can have zero squared length while not itself being zero. (That’s a “null four-vector”, we were talking about, for the uninitiated. You need them for describing things that move at the speed of light, for example.)

I have to design them a final exam very soon. Time for a trip to the Cat and Fiddle then, some evening soon. I’m going to see if I can get in a “fun” question at the end again, like last year. During the exam last year, one student (Lauren Schenkman) raised her hand to ask a question. I thought there was a typo or something on the exam. No, there wasn’t. Her question – asked cautiously and respectfully, was, “Are you serious?”. I love that. Here was the question:

Consider the following lyrics to the song, “’39”, written by Brian May and performed by the rock band Queen back before you were born.

In the year of ’39 assembled here the Volunteers
In the days when lands were few
Here the ship sailed out into the blue and sunny morn
The sweetest sight ever seen.
And the night followed day
And the story tellers say
That the score brave souls inside
For many a lonely day sailed across the milky seas
Ne’er looked back, never feared, never cried.

Don’t you hear my call though you’re many years away
Don’t you hear me calling you
Write your letters in the sand
For the day I take your hand
In the land that our grandchildren knew.

In the year of ’39 came a ship in from the blue
The volunteers came home that day
And they bring good news of a world so newly born
Though their hearts so heavily weigh
For the earth is old and grey, little darlin’ we’ll away
But my love this cannot be
For so many years have gone though I’m older but a year
Your mother’s eyes from your eyes cry to me.

Don’t you hear my call though you’re many years away
Don’t you hear me calling you
All the letters in the sand cannot heal me like your hand
For my life
Still ahead
Pity Me.

Offer a relevant and reasonably self—consistent interpretation of these words, with illustrative equations.

(Sigh. I loved this song so much when I was a teenager…..)

Some ex-Mathematical Physics students of mine from Durham may also recall me using this question one year. Shameless recycling. There, they had to write a little essay over Christmas holidays about it. I still have them. I kept meaning to mail them all to Brian May. Maybe I will, one of these days. Some of them were rather good.

Anyway…..Well? What’s your explanation? What would you have turned in to be graded?

-cvj

CATEGORIZED UNDER: Academia, Music, Science
  • Rufus

    Do you realize that all you ever talk about is yourself? There’s no hint of bigger ideas or more worthy subjects of dicsussion. It’s all you — where you’re traveling, what you’re teaching, how you feel. Please, give us more insight into physics and you speciality, and less about you personally.

  • http://blogs.discovermagazine.com/cosmicvariance/clifford/ Clifford

    Rufus. That’s a really funny thing to say on a blog!! Thanks for that. Read Sean’s post on filtering out the authors you don’t like and hurry along away from here. Run along now. Nobody’s forcing you to stay.

    I’ll write about whatever pleases me, and could not care less what you, Rufus, think. Thanks for the laugh though.

    Cheers!

    -cvj

  • Someone

    Shut up Rufus,
    The site is his and therefore he can write whatever he wants in it. If you don’t like it then dont read his entries. Plus you are being quite disrespectful and he doesn’t give a damn about what u think… As he shouldn’t b/c if u really want to learn physics theen read textbooks not a physics blog!

    “Give us more insight”? As Feynman would have put it: Why do you care what his insights are, what are YOUR insights??

  • http://airminded.org/ Brett

    Hint: Brian May dropped out of a PhD in astronomy when Queen became successful … :P

  • damtp_dweller

    I’d also appreciate hearing a bit more about what it is you actually do, Clifford. Not because I find the other stuff boring (I don’t), but because I would be genuinely interested to hear what you’re working on at the moment.

    Don’t stop talking about the everyday stuff though, I’ve gotten a couple of rather useful recipies from you already :-)

  • http://blogs.discovermagazine.com/cosmicvariance/clifford/ Clifford

    damtp_dweller:- I actually have been working on some interesting projects in collaboration with some of my students. We have some lovely new results. When they are ready to be discussed publicly, and when I am ready to discuss them, I will probably describe them here, as I have in the past for other projects. Let’s hope it does not degenerate into yet another tiresome “strings-evil vs strings-wonderful” grudge match, instead of an interesting conversation…. which I have to say does not really encourage one to talk about string research here that often. But I have to say that the teaching and outreach and other campus activities that I commonly describe here are a big part of “what I actually do”. So it will show up in my descriptions of my job alongside everything else. People who don’t want me talking about teaching and the other stuff will just have to deal with it, or move on. As to my extra-curricular activities…. that’s part of “what I do” as a living, breathing human being who has a life. That’s what this blog (or my 1/5 of it) is about too.

    -cvj

  • Yvette

    I’ve been spending the better part of the month trying to convince a particular physics professor of mine to let us have class outside, but he keeps rationalizing around the issue. Obviously, my mistake lies in the fact that I didn’t enroll at USC…

    As for the question, anything like this deserves an answer with flare, so my response would be something like this:

    It is the year of ’39. There is a crew of twenty who were setting off to explore a faraway planet, hoping to find a place where the humans of Earth could live. In order to make the journey and live to tell about it, the ship would need to take advantage of advanced technology and travel at relativistic speeds: the crew could reach the planet in a few short years to them, while a greater amount of time would have passed by on Earth. In this case, one year for the crew would have a hundred pass by on Earth, which meant the crew would return once again in the year of ’39. [insert equations to amuse the professor here]
    Now imagine you are a member of this crew. You know full well the effects of such a journey, and know how when you part from your love before sailing away it will be the last time you will lay eyes on her. You spend countless nights agonizing over the decision: countless nights of pondering everything that would be lost, of all that would definitively never be again. Why throw away happiness when you have so much already?
    But despite the logic and the heart you know you will break, you know what answer you will choose. You know how if you do not sail away on that ship your heart will still be broken from knowing you stepped away from your chance to explore the universe. You know your life would be plagued for all eternity by questions of “what if?” So you take your chance and sail away, knowing you will never see her again. After all, it’s easy to make choices when you will only deal with repercussions later.
    Now imagine your return: same day, same year, but with a hundred years added on to the date. The are excited: the world you found is fertile and the future of humanity looks bright. As you leave the ship a crowd greets you, and you see a girl who looks like that girl you left a year ago. You don’t know how that is, something about the eyes maybe, and she looks the same but so different…
    You realize what you have done.
    It is the year of ’39. You have explored the universe and conquered faraway worlds, but suddenly this is unimportant compared to all you foolishly left behind. What good is all you have done if there is no one left with whom to share it? You sit down, feeling like something in you has died. You have the rest of your life to live, and you already miss her.

  • http://blogs.discovermagazine.com/cosmicvariance/clifford/ Clifford

    Wow! Not too late to transfer! From your writing skills (and maybe those equations), it tooks like we missed out on having you here!

    -cvj

  • joseph

    Is it a coincidence that the Cosmic Variance Journal is written by Clifford V. Johnson?

    Or did I miss something?

  • Andrei Sobolevskii

    My two cents. I am a university physics teacher in Moscow and I find Clifford’s posts on his teaching really useful. Well… inspiring. Thanks Clifford!

  • http://alun_clewe.livejournal.com Jeff Nuttall

    Heh…I don’t think any of the exams in the physics classes I took ever included questions that lent themselves as well to, um, creative answers like that. (I finished my required classwork before you came to USC, I think…the last few years I’ve just been working on my dissertation. Hopefully I’ll finally be finished before too much longer…)

    I probably would have had a field day with a question like that, though. In high school, in my AP Biology class, the teacher, one Mr. Reid, made the mistake of stating that on the essays, we would get points for any correct information we included, but would not lose points for including wrong information. I guess the intention was to encourage students to include facts they thought they remembered even if they weren’t sure of it. I, however, took this opportunity, just for fun, to insert all sorts of invented details into my essays. In one essay, on the differences between the hearts of animals of the various vertebrate classes, I referenced all sorts of fictitious animals like the “Antarctic jungle newt” and the “polycardial tree frog”. Another essay, on emphysema, I wrote à la Mr. Rogers, referring to things like “Mr. Smoker” and “Mr. Red Blood Cell”. Yet another–I don’t recall the subject–I wrote in the style of a medieval alchemist…

    Mr. Reid, for the most part, took this in stride, and may even have been somewhat amused by it. The only indication that he ever got a bit annoyed by my interpolations was in his comments on one essay, on blood circulation, in which I had written an entire paragraph that began by asking the reader to picture a pump that pumped red paint on one side and blue on the other, and how if one partition went down the colors would mix together and turn to puce, and…well, it kind of wandered further astray as I asked the reader to picture increasingly irrelevant things, and finally ended with the explicit admission that “None of this has anything to do with the essay.” Apparently having finally had enough, Mr. Reid wrote in the margin by that paragraph, “Please don’t waste my time like this. Your handwriting is hard enough to read as it is.”

    Um…speaking of wandering astray and introducing irrelevant things, I’m not sure how much this comment ended up having to do with the subject at hand. Hm. Oh well. Sorry.

  • http://www.irrationalpoint.blogspot.com Quibbler

    Wish that was my homework!

    –Q.

  • http://arunsmusings.blogspot.com Arun

    Clifford,
    Thank you! (for giving me a good read and a smile over my morning tea :), and something to think about all day, how to set a poem to equations :)).

  • cynic

    Rock on Rufus: our host is ever the soul of solipsism.

    BTW, while the rest of the Queen lads could do killer (queen) lyrics, Brian May’s efforts were always a little bit stilted (think Flash Gordan). This may have something to do with his physics background. Check out his chapter in ‘The Guitar: A Guide For Students and Teachers’, Oxford University Press, 1988; the prose style lumbers in straight from the pages of the Physical Review. ” for further examples, the reader is referred to the author’s contributions to ‘A Night at The Opera’ – Rock and Roll or what?!

  • brad

    i’d have been pretty pissed to see that question on a physics exam of mine, personally.

  • PhysicsFan

    PLEASE don’t change Clifford.

    I personally enjoy greatly hearing about the personal AND the political(currently mostly Sean’s department :) ).

    And as someone said, if you just want to get physics there are many excellent textbooks and preprints available (I am sure Clifford can recommend a few).

    I think is nice to get a 360° degree view of what a typical scientist does including personal, academic, political, social and whatever else they do.

    Indeed, it is exactly these “extra dimensions” (pun intended!) material which are most suited to the blogging medium.

  • http://eskesthai.blogspot.com/2006/04/comprehending-new-physics.html Plato

    Going “outside” is very symbolic.:)A park as well. Under a tree even better. Clifford in a white robe? Naw! :)

    Moshe, knows what I mean in regards to the future, and the parks we can visit.

    On worrying about distractions though, I thought a visible shield would might possibly hide the class(reactant to the sun and the polarizations, ach, you now what I mean right?), would not prevent the g(c)lass from seeing the world.

    So what new University Campus might this be in the future? For now, oh well, “Blogging International INCorp,” for the uncreditialled mind viewing beings?

  • spyder

    ’39 sure invokes a great deal of the historical and cultural spectrum. More so for British citizens than those of us here in the “colonies.” I did spend a part of my morning today reading an essay comparing the geographic, climatic, and topological landscapes manifested in the Wizard of Oz and Through the Looking Glass. Somehow i don’t think that counts here though. So i offer these lyric verses as my response:

    I had this dream where I relished the fray
    and the screaming filled my head all day.
    It was as though I’d been spit here, settled
    in, into the pocket of a lighthouse on some
    rocky socket, off the coast of France, dear.

    One afternoon, four thousand men died in
    the water here and five hundred more were
    thrashing madly, as parasites might in your
    blood. Now I was in a lifeboat designed for
    ten and ten only, anything that systematic
    would get you hated. It’s not a deal nor a
    test nor a love of something fated. The
    selection was quick, the crew picked and
    those left in the water got kicked off our
    pantleg and we headed for home.

  • http://woodside.blogs.com/cosmologycuriosity/ CC

    Hmm, interesting. So that’s why Roger Taylor [drummer] ‘jokingly refers to the song “39”, as “Science-Fiction Space Folk” in the “Making Of A Night At The Opera” DVD.’

    Would certainly appreciate it if Clifford can share to us the best (and the strangest/worst/most amusing?) answers to that question.

  • http://blogs.discovermagazine.com/cosmicvariance/clifford/ Clifford

    CC:- Well, if we’re lucky, the people who come up with answers will post them here for all to see. I need do nothing. Yes, despite claims to the contrary, this is another of my regular “I want to hear from you about what you think” posts, aimed at getting everyone to participate….

    So let’s get some more answers!!

    Cheers,

    -cvj

  • Harv

    That’s a really cool question! And I do like hearing about personal things, especially since I’m in a similar field. It helps us young scientists to hear others talk about their personal lives. Thanks!

  • Rob

    Spyder, you left out the best two lines:
    Anyway Susan if you like our conversation is as faint as the sound in my memory, As those fingernails scratching on the hull

  • http://www.math.columbia.edu/~woit/wordpress/?p=380#comment-10070 Plato
  • http://woodside.blogs.com/cosmologycuriosity/ CC

    Clifford, thanks for the comment.

    This continues to be very interesting.

    I have nothing original to add. I found however this article. And also this wacky article on ’39’ and relativistic time travel. Which made me think (anybody: pls feel free to point out the flaw in the logic) —

    [a] to experience time dilation, one has to reach near-light speed velocity;

    [b] for the ship to do so, the amount of energy needed would be tremendous; so huge in fact that it would be physically impossible for the ship to carry the ‘fuel’ that will eventually propel it to the desired speed;

    [c] the other practical issue to deal with would be the length of time needed to reach near-‘c’ speed, i.e., if the link/s above are correct, at 1g acceleration so as not to kill the volunteers the speed after 1 year of travel (relative to the inertial frame in which ship was stationary at t=0) would just be 0.77c, and it will take 5 yrs to reach say 0.99993c, a speed where time dilation would really kick in;

    [d] hence, the volunteers would need more than 1 year to accelerate and a similar period to decelerate; however, the song says that the volunteers were away for just one year (what gives?);

    [e] to my mind thus, the only way the volunteers could have done their exploration in just a year’s time would be via wormholes but I don’t think we can find that in the song (and would time dilation occur in such a scenario?).

    Or perhaps the convenient answer to all of the above would be ‘poetic license’?

    CC

    PS – Can you at least share to us some of the supporting equations given by the class? :)

  • Ambitwistor

    Don’t you hear my call though you’re many years awayDon’t you hear me calling you

    I bet you could work causal Rindler horizons into this somehow…

  • SteveM

    If you do a GR course you could use these lyrics from Canadian virtuoso rockers “Rush”, from their album “A Farewell to Kings”:

    In the constellation of Cygnus, there lurks a mysterious force–the black hole of Cygnus X-1…
    Six stars of the Northern Cross
    In mourning for their sister’s loss
    In a final flash of glory
    Nevermore to grace the night…

    Invisible to telescopic eye
    Infinity, the star that would not die
    All to dare to cross her course
    Are swallowed by a fearsome force
    Through the void
    To be destroyed
    Or is there something more?
    Atomized…at the core?
    Or through the astral door?
    To soar…

    The X-ray is her siren song
    My ship cannot resist her long
    Nearer to my deadly goal
    Until the black hole
    Gains control…

    Spinning, whirling
    Still descending
    Like a spiral sea
    Unending…
    Sound and fury
    Drown my heart
    Every nerve is torn apart…

  • David

    Can we get an extra credit like this on our final too? Or would the other prof not be too happy about that? :p

  • http://www.amara.com/ Amara

    Hey. thanks for the ‘wake-up’ Plato. I didn’t think anybody read my wikipedia cosmic dust entry; it’s still 99% still my words after 8 months of being at the site. I’m back at home, lazy for once, after mostly traveling during the last 5 weeks (hard work and some fun). Now, catching up on what’s up at cosmic variance, I know that I owe Clifford some words about the solar eclipse. I’m not satisfied with the scan of my photos (which were not of the eclipse but of the people around me), I will try to scan my negatives instead, and I need to transcribe my thoughts into a story. In the meantime, you can see some photos from someone I met on the way to our eclipse site: the dervish meditation hill above Hacibektas, Cappodochia, Turkey. This is the blog and photo page of a remarkable young man, Ryan Turner, whose passport is likely as full as mine: http://compassroze.blogspot.com His time-lapse photo of our day under the magnificent sun captured the mood and movements nicely.

    Clifford’s method of teaching while ‘sitting under a tree’ … How about something from the sufis? They use this image in combination with other “picture words” to explain the tariqa. Lovely idea! http://www.amara.com/athousand/Onethousandandone.html#picturewords

  • http://blogs.discovermagazine.com/cosmicvariance/clifford/ Clifford

    Those of you who made such pleasant and encouraging remarks. Thanks!

    -cvj

  • http://blogs.discovermagazine.com/cosmicvariance/clifford/ Clifford

    Amara! How the devil are you? You’ve been missed here at CV. Welcome back.

    -cvj

  • http://eskesthai.blogspot.com/2006/04/is-door-open-to-eruption-of-sociology.html Plato

    Amara,

    Good work on those dust particles. Following up on Clifford’s question about the song is all. :)

    Some of us might have read about Gurdieff and Ouspensky and the spreading of a philosophy? Gave us a flavour of the Dervish ways. Spinning.

    They use this image in combination with other “picture words” to explain the tariqa. Lovely idea!

    To me, that is a wonderful way to work. Each picture leaves a space(quark to quark measure in analogy?), for more ideas to enter. While it is historical(self remembering), it might support the movement forward.

    Mean anything to you?

  • Pingback: Navel-Gazing Links | Cosmic Variance()

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