# Physicists: What makes sense on this gigantic blackboard, and how much holds together topically? **URL:** \ **Category:** Factual Questions\ **Created:** [July 17, 2013, 4:01pm UTC](https://boards.straightdope.com/t/physicists-what-makes-sense-on-this-gigantic-blackboard-and-how-much-holds-together-topically/663764 "2013-07-17T16:01:11Z")\ **Posts on this page:** 16\ **Page:** 3
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [December 3, 2017, 4:41am UTC](https://boards.straightdope.com/t/physicists-what-makes-sense-on-this-gigantic-blackboard-and-how-much-holds-together-topically/663764/41 "2017-12-03T04:41:30Z")
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. ---
**Author:** ![Derleth](https://avatars.discourse-cdn.com/v4/letter/d/b9e5f3/32.png) [@Derleth](https://boards.straightdope.com/u/Derleth)\ **Post date:** [December 3, 2017, 4:41am UTC](https://boards.straightdope.com/t/physicists-what-makes-sense-on-this-gigantic-blackboard-and-how-much-holds-together-topically/663764/42 "2017-12-03T04:41:50Z")
[quote=“friedo, post:40, topic:663764”] [/QUOTE] I love the Internet: Instant rimshots! ---
**Author:** ![Melbourne](https://avatars.discourse-cdn.com/v4/letter/m/b5e925/32.png) [@Melbourne](https://boards.straightdope.com/u/Melbourne)\ **Post date:** [December 3, 2017, 9:05am UTC](https://boards.straightdope.com/t/physicists-what-makes-sense-on-this-gigantic-blackboard-and-how-much-holds-together-topically/663764/43 "2017-12-03T09:05:19Z")
> [@smithsb](#): > > Similar blackboards and formula were depicted and included the ladders to reach high spots. > [Redirect Notice](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. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [December 3, 2017, 7:35pm UTC](https://boards.straightdope.com/t/physicists-what-makes-sense-on-this-gigantic-blackboard-and-how-much-holds-together-topically/663764/44 "2017-12-03T19:35:32Z")
> [@Leo\_Bloom](#): > > 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… > > > [@friedo](#): > > > > …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? ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [December 15, 2017, 8:51pm UTC](https://boards.straightdope.com/t/physicists-what-makes-sense-on-this-gigantic-blackboard-and-how-much-holds-together-topically/663764/45 "2017-12-15T20:51:49Z")
[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. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [December 15, 2017, 10:47pm UTC](https://boards.straightdope.com/t/physicists-what-makes-sense-on-this-gigantic-blackboard-and-how-much-holds-together-topically/663764/46 "2017-12-15T22:47:53Z")
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. ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [December 15, 2017, 10:58pm UTC](https://boards.straightdope.com/t/physicists-what-makes-sense-on-this-gigantic-blackboard-and-how-much-holds-together-topically/663764/47 "2017-12-15T22:58:28Z")
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? ---
**Author:** ![Claude\_Remains](https://avatars.discourse-cdn.com/v4/letter/c/898d66/32.png) [@Claude\_Remains](https://boards.straightdope.com/u/Claude_Remains)\ **Post date:** [December 16, 2017, 12:08am UTC](https://boards.straightdope.com/t/physicists-what-makes-sense-on-this-gigantic-blackboard-and-how-much-holds-together-topically/663764/48 "2017-12-16T00:08:31Z")
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. ---
**Author:** ![joema](https://avatars.discourse-cdn.com/v4/letter/j/a9adbd/32.png) [@joema](https://boards.straightdope.com/u/joema)\ **Post date:** [December 16, 2017, 2:43pm UTC](https://boards.straightdope.com/t/physicists-what-makes-sense-on-this-gigantic-blackboard-and-how-much-holds-together-topically/663764/49 "2017-12-16T14:43:07Z")
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://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://rjamahoney.files.wordpress.com/2017/01/bob-37.png?w=584) [![](https://i.pinimg.com/originals/4b/b2/3f/4bb23f3c11f7a33b023756bbd8e57258.png) ](https://i.pinimg.com/originals/4b/b2/3f/4bb23f3c11f7a33b023756bbd8e57258.png) ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [December 16, 2017, 3:31pm UTC](https://boards.straightdope.com/t/physicists-what-makes-sense-on-this-gigantic-blackboard-and-how-much-holds-together-topically/663764/50 "2017-12-16T15:31:28Z")
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. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [December 16, 2017, 4:04pm UTC](https://boards.straightdope.com/t/physicists-what-makes-sense-on-this-gigantic-blackboard-and-how-much-holds-together-topically/663764/51 "2017-12-16T16:04:04Z")
I do know that in the corresponding scene in the re-make, the board contents were provided by my advisor. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [December 16, 2017, 9:53pm UTC](https://boards.straightdope.com/t/physicists-what-makes-sense-on-this-gigantic-blackboard-and-how-much-holds-together-topically/663764/52 "2017-12-16T21:53:25Z")
> [@joema](#): > > 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://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://rjamahoney.files.wordpress.com/2017/01/bob-37.png?w=584) > > [https://i.pinimg.com/originals/4b/b2/3f/4bb23f3c11f7a33b023756bbd8e57258.png](https://i.pinimg.com/originals/4b/b2/3f/4bb23f3c11f7a33b023756bbd8e57258.png) Hey **joema** , welcome aboard to my side of the game! ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [December 23, 2017, 9:52pm UTC](https://boards.straightdope.com/t/physicists-what-makes-sense-on-this-gigantic-blackboard-and-how-much-holds-together-topically/663764/53 "2017-12-23T21:52:12Z")
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) ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [December 23, 2017, 10:24pm UTC](https://boards.straightdope.com/t/physicists-what-makes-sense-on-this-gigantic-blackboard-and-how-much-holds-together-topically/663764/54 "2017-12-23T22:24:28Z")
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. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [December 23, 2017, 11:14pm UTC](https://boards.straightdope.com/t/physicists-what-makes-sense-on-this-gigantic-blackboard-and-how-much-holds-together-topically/663764/55 "2017-12-23T23:14:38Z")
I’ll scrounge around for more images. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [December 26, 2017, 2:39pm UTC](https://boards.straightdope.com/t/physicists-what-makes-sense-on-this-gigantic-blackboard-and-how-much-holds-together-topically/663764/56 "2017-12-26T14:39:57Z")
[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? [Previous page](https://boards.straightdope.com/t/physicists-what-makes-sense-on-this-gigantic-blackboard-and-how-much-holds-together-topically/663764.md?page=2)