View Full Version : Physicists: What makes sense on this gigantic blackboard, and how much holds together topically?

Leo Bloom

07-17-2013, 11:01 AM

In a current thread Can those brilliant professor types really look at those long ass equations on the whiteboard? (http://boards.straightdope.com/sdmb/showthread.php?t=696770), I posted the following example, and commented on it as an aside:

A physicist's anxiety nightmare. (http://tywkiwdbi.blogspot.com/2012/04/physics-classroom-blackboard.html)

From a dream-sequence in Coen Bros. 2009, A Serious Man. The only movie where Schroedinger's Cat is knowledgeably introduced into a meditation on a man's Job-like moral and existential quandaries. Really.

The main character is a physicist who is currently lecturing on quantum reality (in other scenes), and his entire mental and real life explicitly relates to the brilliant and funny movie.

Anyway, since I brought it up in a thread about how people can read (correct or "incorrect" symbols), it seemed kind of unfair to keep people--including me--hanging about this example.

How far did the set-designer/directors go in verisimilitude? Remember, also, that this is a snip from an anxiety dream, where logic is slippery.

A lot of it seems to be too blurry to read in the linked pic.

Clearly, even if it all actually means something, it is unrealistic as a lecture. No student could take all that in at once.

Leo Bloom

07-17-2013, 11:16 AM

Yeah, for sure.

You can click on the picture to see a large view of it if you want.

Machine Elf

07-17-2013, 11:43 AM

A lot of it seems to be too blurry to read in the linked pic.

You can blow the JPG (http://4.bp.blogspot.com/-V1E8ODdrLg4/T3nE-eg7_PI/AAAAAAAAQN8/A9Vy3l7x-d4/s1600/blackboard.jpg) image up to full size, and then zoom in on it. Even so, I'm not getting a whole lot.

In the upper right corner, I see the wavelength/momentum equation (lambda = h/p), and a visual depiction of an electron as a wave function orbiting a nucleus. (http://ircamera.as.arizona.edu/astr_250/Lectures/Lec08_sml.htm)

Halfway up the blackboard and a bit to our right of the instructor, I see an expression for total system momentum (P=sum (m1*v1 + m2*v2+...).

At bottom, halfway between the instructor and our right end of the board, I see a visual depiction of a solenoid or transformer in cross section, showing the magnetic field lines. (http://physics.stackexchange.com/questions/38067/magnetic-field-lines-can-be-entirely-confined-within-the-core-of-a-toroid-but-n)

Over on our left half, there's a visual depiction of a differential element of solid angle (a steradian (http://www.google.com/search?safe=active&hl=en&site=imghp&tbm=isch&source=hp&biw=1078&bih=819&q=coil+field&oq=coil+field&gs_l=img.3...1453.2219.0.2297.10.6.0.0.0.0.125.125.0j1.1.0....0...1ac.1.21.img.4bk78Qf7cF8#safe=acti ve&hl=en&site=imghp&tbm=isch&sa=1&q=steradian&oq=steradian&gs_l=img.3..0l5j0i10i24l2j0i24l3.3016.4750.1.4875.13.9.0.0.0.0.281.1123.0j2j3.5.0....0...1c.1.21.img .S7xDsN7I6Fs&bav=on.2,or.r_qf.&fp=cda15bd43fa71479&biw=1078&bih=819)), along with the integral function using it to calculate total flux of some quantity (gravity, radiation, etc.) emanating from a point source in all directions.

A pic at top left shows another example of electrical current in a loop interacting with magnetic field lines passing through the loop.

That's about as much as I can make out. It seems likely that the rest of it has some basis in reality, e.g. they may have copied it all from a physics text, but not necessarily anything the Coen brothers could point to and say "this means *."

Half Man Half Wit

07-17-2013, 12:00 PM

From a quick look, most of what I can make out seems to be straight from some introductory quantum mechanics course---there's the old classic, the quantum harmonic oscillator both in 3d (in the form of its energy eigenvalues) and in 1d (in the form of the probability density for finding the particle at a certain position, if the system is in a certain state---the graphic with the sinusoidal line at the very top over the professor), Bohr's atom model (top right), the quantization of spin, etc. There's also some special relativity, and a bit of electrodynamics (I can make out at least a couple of Maxwell's equations). Some of the things appear to hang together---there seems to be a discussion of the volume element in spherical coordinates, which might be related to the calculation of the energy levels of the three dimensional harmonic oscillator, and it seems that a discussion about magnetic dipoles was used to introduce spin, but for others, there does not seem to be any obvious connection---I'm not sure what the relativistic energy-momentum relation does there, for instance.

One thing I can't place is the quite central bit with the arrows and (what looks like) Hebrew symbols; it looks vaguely familiar, but perhaps not from a physics context?

And of course, one question all those equations can't solve: how the heck did he manage to write all the way up there?

friedo

07-17-2013, 12:28 PM

And of course, one question all those equations can't solve: how the heck did he manage to write all the way up there?

Quantum teleportation.

Yeah, for sure.

You can click on the picture to see a large view of it if you want.

I did that before my original post, thanks very much. Much of it is still too blurry to read. I am not denying that some parts may be recognizable (or guessable at).

Prof. Pepperwinkle

07-17-2013, 02:57 PM

One thing I can't place is the quite central bit with the arrows and (what looks like) Hebrew symbols; it looks vaguely familiar, but perhaps not from a physics context?

The symbols (alephs and tsades) I believe are used in infinite (or transfinite) mathematics.

Chronos

07-17-2013, 03:49 PM

All of it seems to be legitimate physics (or possibly math, in the case of the alephs), but it's drawn from all over the place in physics. No single course would contain all those concepts, much less any single lecture.

Itself

07-17-2013, 04:02 PM

The vast majority of it looks like straightforward quantum mechanics: energy eigenvalues of the harmonic oscillator, some bits about quantum numbers, spin and magnetic moment for an electron, Schrodinger's equation written out with vector notation, something about spherical harmonics, etc. The panel to the immediate right of the lecturer looks like electromagnetism in relativistic quantum mechanics. The drawing on the far left looks like a description of some sort of atomic process (I can't see enough detail to be more specific), and the one on the bottom right might be a history of atomic models. I have no idea what the Hebrew letters on the panel to the left of the lecturer are supposed to represent; I've only seem them used in set theory (and the diagram makes no sense in that context), not in physics (but I'm a mathematician, not a physicist, and not really even a mathematical physicist). The bit about L^2 immediately above it is very standard quantum mechanics, at least.

MikeS

07-17-2013, 09:33 PM

Another physicist here to chime in that this is basically a collage of various physics concepts, without any particular unifying theme. However, it's worth pointing out that the Hebrew letters may also have been included because the main character (the professor in the picture) is Jewish, and spends most of the movie trying to figure out what God wants from him.

Half Man Half Wit

07-18-2013, 12:20 AM

The symbols (alephs and tsades) I believe are used in infinite (or transfinite) mathematics.

Alephs and beths I know in that context, but what do the tsades signify? Maybe, as MikeS said, one should rather look at a religious context for this bit of symbology...

Leo Bloom

03-28-2016, 10:48 AM

To continue: Cat and toddler thinking about gravitation?

http://imgur.com/DpIggh0

How together is the math?

FTR, I revived this thread, and not the one cited in OP, or http://boards.straightdope.com/sdmb/showthread.php?t=757515, which are similar, if you're into this type of thing.

Leo Bloom

03-28-2016, 11:03 AM

It occurs to me that the dynamics and ductus of the notation and graphing on the board are that of someone fluent and comfortable in the field.

Which makes me wonder in particular about the crossed out part, if it's jokey in addition.

(Handwriting analysis glossary: http://atozhandwriting.com/graphology/dictionary-of-handwriting-analysis/)

MikeS

03-28-2016, 11:34 AM

To continue: Cat and toddler thinking about gravitation?

http://imgur.com/DpIggh0

How together is the math?It's all from the same field, but it's a bit sloppy. All of the equations appear to be from the field of general relativity:

The circled equation, partially blocked by the child's head, is the Einstein equation (https://en.wikipedia.org/wiki/Einstein_field_equations) that describes the interaction of spacetime with matter.

The long multi-line equation in the upper right looks most like the Kerr metric (https://en.wikipedia.org/wiki/Kerr_metric) to me, but it might be the Kerr-Newman metric (https://en.wikipedia.org/wiki/Kerr%E2%80%93Newman_metric) in a form that I'm not familiar with. The former describes rotating black holes; the latter describes rotating black holes that additionally have electric charge.

The equations in the bottom left appear to be describing the relationship between the total mass of an object (not necessarily a black hole) and the density of the matter comprising it.

The equations in the upper left seem to be describing the two characteristic length scales for charged black holes (one related to its mass—the so-called Schwarzchild radius (http://astronomyonline.org/science/schwarzschildradius.asp), and another related to its charge. I'm not sure whether this second one has a special name.)

I'm not sure what the diagrams are supposed to represent, but if I saw them drawn on a chalkboard in a general relativity research group I wouldn't bat an eye.

Here's the original photo posted by the photographer, BTW. (http://photo.net/photodb/photo?photo_id=15426772)

Leo Bloom

03-28-2016, 11:43 AM

Thanks for the proper cite. I was unhappy about not having it, but the artist's name was visible.

And the crossed-out part?

MikeS

03-28-2016, 12:01 PM

And the crossed-out part?Looks like a partial definition of the Einstein tensor, (https://en.wikipedia.org/wiki/Einstein_tensor) also with the cosmological constant thrown in for good measure. It's certainly conceivable that these two would be in the same equation. As far as I can tell, the equation isn't complete; but it's not unheard of to start writing down an equation, realize as you're writing it that it's better expressed in a different way, and scratch it out and rewrite it. (I do it all the time.)

Chronos

03-28-2016, 05:02 PM

And I would assume that the diagrams are meant to represent wormholes.

Leo Bloom

09-02-2016, 11:37 AM

OK class. Last time, we had a kid and a cat, very popular Internet topics. Today we have a another popular item, a pretty woman.

http://imgur.com/CHHXHVP

Same query as OP.

Extra credit: cite most likely source.

ETA: of the math for the set designer

Pasta

09-02-2016, 12:34 PM

A lot of background info is here (http://scifi.stackexchange.com/questions/72737/interstellar-movie-equations-shot).

Half Man Half Wit

09-02-2016, 12:35 PM

The blackboard is from Interstellar, but I can't make out enough of the math to see what it's about---to the left, there's something about 'brane' and 'curvature', which would make sense in the context of some hypothetical future gravitational theory---IIRC, they were hypothesizing about a kind of 'braneworld'-scenario, where our universe is just a kind of surface---a brane---in a higher-dimensional space. The bits in braces seem to be mostly values for certain parameters.

The movie had Kip Thorne as a scientific advisor, so most of the physics (on the blackboard) is probably speculative, but not outrageously so---in fact, he's written a book, The Science of Interstellar, which should cover most of what's on those boards.

(By the way, do you just do google searches for 'math blackboard' every once in a while, or how do you find these?)

Half Man Half Wit

09-02-2016, 12:41 PM

You can actually see Thorne having a look at the stuff on the blackboard in this picture (http://i.imgur.com/zQm55Q9.jpg).

Chronos

09-02-2016, 02:40 PM

Yeah, it's tough to say much about this latest picture without context (those Ws could stand for almost anything), but it does appear to be tensors of some sort, which is consistent with it being GR.

The fact that the Ws have subscripts of "w" and "y" suggests, to me, that there's a w coordinate being used in addition to the familiar x, y, z, and t, which would be consistent with it being brane work.

Leo Bloom

10-13-2016, 03:24 PM

...

(By the way, do you just do google searches for 'math blackboard' every once in a while, or how do you find these?)

No. I'm just slow on the uptake (as one poster put it) of mass-ish culture, and like it when I see other bits of culture appropriated. In fact, just got around last night to seeing this next one. So it's kind of a gimme, I guess, but I don't know what the problem is called, although he mentions the general field (no idea if what he says is right, or how, of course): https://imgur.com/a/zU0wA

But in Googling around for that image (actually, Bing-ing, but sucks to be Microsoft), I did find this, the source of which I did _not_ see, but is worth mentioning because it is not dissimilar in presentation to others: https://imgur.com/DnAKFWV

Leo Bloom

10-27-2017, 09:22 PM

One more. (http://pleated-jeans.com/wp-content/uploads/2017/10/sbil-15.jpg) Math is simpler, more my speed.

But damn, that handwriting is good, and not dissimilar to the script in the last cite above. Which my keen eyes for anatomy tell me is not the same body plane. Could be his...

Is it really (as I suspect) it's trying to be, "let's do something funny with a guy passed out drunk?"

Chronos

10-28-2017, 10:05 AM

Mostly trigonometry, with a few geometry formulas. It looks like what a student might put on a one-page "cheat sheet" for a test (in quotes because professors will often explicitly allow a single sheet, and so it's not actually cheating), but which a professional probably wouldn't bother with because they'd have it all memorized.

The lower-left quadrant is the geometry formulas, it looks like mostly surface area and volume. The lower-right quadrant is the graphs of sine, cosine, tangent, and cotangent. On the top left, we have a labeled diagram of a triangle, giving the definitions of the various trig functions, then to the right of that an abbreviated table of values of trig functions for some often-encountered angles, then below that a labeling of the quadrants of the plane, then below that some often-used trig identity formulas.

Chronos

10-28-2017, 10:10 AM

Actually, let me amend that: The diagrams and graphs look rather neat to be student work. So it might instead be a pre-printed reference sheet provided by the teacher for the students, copied exactly onto the guy's back. And yes, the most likely reason is as a prank on a passed-out guy, because its not like he can read them himself, nor is he going to be lifting up his shirt in the middle of a test to help out the student behind him.

smithsb

10-28-2017, 08:41 PM

Don't forget the story of Katherine Johnson and women behind the mathematics at NASA in the film Hidden Figures. Excellent film.

https://en.wikipedia.org/wiki/Katherine_Johnson

https://en.wikipedia.org/wiki/Hidden_Figures

Similar blackboards and formula were depicted and included the ladders to reach high spots.

https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwjZqOij2pTXAhWDMSYKHWXSAV0QjRwIBw&url=http%3A%2F%2Fwww.beyond50radio.com%2FConscious_Movie_Reviews-Hidden_Figures.html&psig=AOvVaw0AZ6dmk-eTa-Uz9hsK92kN&ust=1509327769645910

AND. There is another joke image somewhere showing a janitor erase/correct the wall of numbers in the lab.

mixdenny

10-29-2017, 03:01 PM

Actually, let me amend that: The diagrams and graphs look rather neat to be student work. So it might instead be a pre-printed reference sheet provided by the teacher for the students, copied exactly onto the guy's back.

It's so neat I wonder if it is Photoshopped onto the photo? Otherwise, they were using rulers on the guy's back, and oval templates. Who can draw sine waves that perfect on a moving plane?

Dennis

Senegoid

10-29-2017, 04:27 PM

This is why rockets blow up.

What's eight times seven? (http://imgc.allpostersimages.com/images/P-473-488-90/65/6587/R6K2100Z/posters/ed-fisher-say-i-think-i-see-where-we-went-off-isn-t-eight-times-seven-fifty-six-new-yorker-cartoon.jpg) (New Yorker cartoon by Ed Fisher)

This makes by brane hurt.

Chronos

10-29-2017, 05:42 PM

I was thinking they used either a projector or a printout on porous paper, and traced over it with marker. But I'll admit that it's hard to imagine either being present in a context where students would be passed out drunk.

Quercus

10-29-2017, 06:08 PM

Looks posed to me. The lettering in the lower left seems to bend the exact same way his back is bending there, meaning it was written when he was standing or lying straight. Plus the lines in the lower right go down into his pants; I don't really see pranksters pulling down the drunk guys pants to get the lines right then carefully pulling them back up again.

Chronos

10-29-2017, 06:25 PM

As an aside, it used to be quite common for movies showing "smart folks" to have blackboards covered in mathematical symbols, but for the symbols to just be arranged randomly. Which looks about as wrong to us math/science types as a board covered in random letters does to an ordinary person. It's one thing for a board full of text to contain words you don't know, or even for it to be in a language you don't know: It'll still look like writing, in a way that just random letters wouldn't. In a similar way, blackboards covered with equations look real (to us) in a way that just random symbols don't.

Thankfully, Hollywood has mostly now learned that technical advisors work for cheap, and are happy to cover a few boards with meaningful symbols to put in the background of a classroom or laboratory shot.

Leo Bloom

12-02-2017, 06:56 PM

I found this (https://imgur.com/g3RwraB) in my saves from a few years ago and don't think I posted it for OP query; although the word expansion series is in my mind and its presence there is otherwise unaccountable.

This actually looks an honest-to-God tattoo, which merits its appearance here anyway (unless its upthread :)).

Darren Garrison

12-02-2017, 07:22 PM

What's eight times seven? (http://imgc.allpostersimages.com/images/P-473-488-90/65/6587/R6K2100Z/posters/ed-fisher-say-i-think-i-see-where-we-went-off-isn-t-eight-times-seven-fifty-six-new-yorker-cartoon.jpg) (New Yorker cartoon by Ed Fisher)

But what do you get if you multiply six by nine?

What's the query? Unless it is a real tattoo, in which case it would be why would anyone get a large ugly tattoo of what looks like something reproduced from a printed textbook (no calligraphy or shaded drawings or anything involved), and a kids' elementary calculus textbook at that.

Chronos

12-02-2017, 08:18 PM

It's a line-by-line proof of the famous equation from Euler, e^(i*pi) = -1, using the Taylor series expansions for the exponential function, sine, and cosine. Which is actually a fairly clumsy way to prove it, but I suppose it works.

friedo

12-02-2017, 08:23 PM

It's a line-by-line proof of the famous equation from Euler, e^(i*pi) = -1, using the Taylor series expansions for the exponential function, sine, and cosine. Which is actually a fairly clumsy way to prove it, but I suppose it works.

I think it's the best way to prove it. I also think we've had this exact discussion before over this exact picture. I need a drink.

Derleth

12-02-2017, 09:59 PM

I think it's the best way to prove it. I also think we've had this exact discussion before over this exact picture. I need a drink.You mean that equation has us going in circles?

friedo

12-02-2017, 10:01 PM

You mean that equation has us going in circles?

https://www.youtube.com/watch?v=9CdVTCDdEwI

Chronos

12-02-2017, 10:41 PM

Well, Indistinguishable explains it better than I. But the gist is, Taylor series expansions aren't a very interesting or informative way to describe such rich functions as the exponential and trig functions, and it's far more elegant to describe them in terms of their more interesting properties.

Though certainly the Taylor series are the most common way to prove it, and the one you're likely to see in textbooks.

Derleth

12-02-2017, 10:41 PM

https://www.youtube.com/watch?v=9CdVTCDdEwII love the Internet: Instant rimshots!

Melbourne

12-03-2017, 03:05 AM

Similar blackboards and formula were depicted and included the ladders to reach high spots.

https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwjZqOij2pTXAhWDMSYKHWXSAV0QjRwIBw&url=http%3A%2F%2Fwww.beyond50radio.com%2FConscious_Movie_Reviews-Hidden_Figures.html&psig=AOvVaw0AZ6dmk-eTa-Uz9hsK92kN&ust=1509327769645910

But if it's a university, it's more likely to be on a roller.

Leo Bloom

12-03-2017, 01:35 PM

I found this (https://imgur.com/g3RwraB) in my saves from a few years ago and don't think I posted it for OP query; although the word expansion series is in my mind and its presence there is otherwise unaccountable...

....I [...] think we've had this exact discussion before over this exact picture. I need a drink.

Yes, me too, as I said on this re-animation...But I remembered "expansion," which even graphically is clear; another proof that somethings that get in SDGQ stick around in my brain somewhere...

But a quick check showed up -0.99999... evidence. Tiz a puzzle.

But: real tattoo or not?

Leo Bloom

12-15-2017, 02:51 PM

Stock photo (cartoon) of "smart guy/Professor" (zoomable). (https://thumb7.shutterstock.com/display_pic_with_logo/85701/85701,1236630275,1/stock-photo-funny-cartoon-professor-standing-by-the-blackboard-against-white-background-26355649.jpg)Plain old calculus, to my eye. Coherent?

ETA: Einstein image-derivative (no P intended), of course.

Chronos

12-15-2017, 04:47 PM

It looks like it might mean something, but what it's hard to say without more context. All the 'z's suggest complex analysis, but that doesn't narrow things down all that much, and besides there's no reason one can't use z for just any old ordinary variable.

It's coherent enough (compare Abel's theorem) with the conclusion at the top, but the key question is, what is it for? Clearly it was taken out of a specific context, but what was that context?

Claude Remains

12-15-2017, 06:08 PM

I'm just a guy who dropped out of high school and am now back in trade school. I've always wondered about blackboards full of scientific notation and figured I'd never have a clue.

Very quickly I found that there's a reason trades are in demand and it's not a joke to go back to school.

There's a reason why you'll never see a movie called "Larry the air conditioning guy".

On my first day of class I was head first into the deep end and found myself face to face with said equations.

In my second semester i was nominated and inducted into the National Technical Honor Society.

after all that I may never have to do the maths out in the field due to apps and smart tools.

joema

12-16-2017, 08:43 AM

In the 1951 move "The Day the Earth Stood Still", equations on a black board were featured:

https://2.bp.blogspot.com/-VfYKC38gyoU/Vn21l4P5W5I/AAAAAAACgps/u70Yg5TKRL0/s1600/WTW-20-IMG_DayEarthStoodStill_42.jpg

https://rjamahoney.files.wordpress.com/2017/01/bob-37.png?w=584

https://i.pinimg.com/originals/4b/b2/3f/4bb23f3c11f7a33b023756bbd8e57258.png

Some variant of the three-body problem? The trouble with blackboards like this, and the previous one, is that it is like taking a snapshot of someone's random scratch paper, or the middle of a long proof in the middle of a lecture.

Chronos

12-16-2017, 10:04 AM

I do know that in the corresponding scene in the re-make, the board contents were provided by my advisor.

Leo Bloom

12-16-2017, 03:53 PM

In the 1951 move "The Day the Earth Stood Still", equations on a black board were featured:

https://2.bp.blogspot.com/-VfYKC38gyoU/Vn21l4P5W5I/AAAAAAACgps/u70Yg5TKRL0/s1600/WTW-20-IMG_DayEarthStoodStill_42.jpg

https://rjamahoney.files.wordpress.com/2017/01/bob-37.png?w=584

https://i.pinimg.com/originals/4b/b2/3f/4bb23f3c11f7a33b023756bbd8e57258.png

Hey joema, welcome aboard to my side of the game!

Leo Bloom

12-23-2017, 03:52 PM

No spoilers yet if you know the movie, which is as a genre topic is actually unique, as far as I know. Just the math, please. (https://imgur.com/Z0NIpuT)

Chronos

12-23-2017, 04:24 PM

The 1/(2pi*i) is probably a hint that we're doing a Fourier transform of something, and the Phi might be a quantum mechanical wavefunction. But the really juicy bits look like they'd be behind the guy's head in that shot.

Leo Bloom

12-23-2017, 05:14 PM

I'll scrounge around for more images.

Leo Bloom

12-26-2017, 08:39 AM

Backstage from same movie (https://imgur.com/kYjgFIh); different blackboard. Even gives a name.

Can you fill in the obscured math in the preceding blackboard now with this money shot?

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