German, French; potato, pohtahtoh

I'm not a recipe follower though I do love to cook.  In recent years, with the ease of access to recipes of all kinds on the internet, I have taken to looking at 2 or 3 recipes online before I cook and then following none of them.  However, I find it grounding in my process and looking at those recipes certainly gives me ideas. 

Imagine my surprise when I decided to make a dish I had not made in years and googled "German Potato Salad".  I'm like, what's with the bacon everywhere?  This is not how Mama made it!  It slowly dawned on me that I had never before actually looked up a recipe for Potato Salad and had just been winging it by imitating my childhood memories.  Then, I realized in a fit of deep intellectual insight: "Hey, my Mom is actually French, not German so...." and then when I googled "French potato salad" I started seeing dishes that looked much more like what I was expecting.  Anyway, I promptly ignored all those "French Potato Salad" recipes and did my thing:

So, I have come to realize that Americans like to call any cold potato salad that is not mayonnaise based as "German".  But of course, every region in the world has their own way of flavoring up some boiled potatoes! (apparently, just within Germany the regional differences are so big it doesn't really make sense to glom it all together as one dish). 

I have a strong memory of when I first came to think of 'my' dish as "German Potato Salad" (growing up, Mom did not name the dishes; She served them and then I ate them and that was that). It was actually in grad school.  A bunch of us CMU physics grad student nerds were having a pot luck dinner at someone's house.  (Elaine's house, Shadyside, Pittsburgh circa 1993?)  I made this salad for some reason.  One guy (Eldon?) LOVED it and I can still picture him pointing at his second serving emphatically and saying "This is really good German Potato Salad, Ken!"  He said it in an authoritative way like someone who really knows their German potato salads so I thought "Hmm, that must be what that dish is called." 

Thank you for your excellent answers

Sometimes grading is fun.  For example, check out some of these answers from a recent test in honors astronomy:

I guess I really emphasize how much Vera Rubin missed out in recognition because she was a woman:

You know, imitation is the sincerest form of flattery:

Time to sketch either a sideways Saturn or Uranus (which is already on its side!) in the middle of a questions about fundamental particles:

Wish I had thought to scan in fun answers earlier in my career!  Better late than never?

Lapin

Recently, while shopping at H-Mart, I realized I had never cooked rabbit for the kids.  So, I bought a frozen one on impulse.  Today, we had the wood stove going, and I love to use that surface to cook soups on.  Well, you see where this is going...

Step one:  Rabbit with onions, celery, and garlic

Step two: Mushrooms

Carrots potatoes and wine/chicken stock 

Fours hours later, dinner is served!

The verdict?  "Dad, this tastes like chicken.  Next time just make your usual coq-au-vin."

Inertial Paths, Fake Forces, and Rotating Spaceships

Recently I just read a whole bunch of relatively shabby explanations from students of why rotating spaceships can simulate gravity.  These are seniors who have taken a full year of physics and are currently in my astronomy class so they are well equipped to give a decent explainer, but most of them just said something like "centripetal centrifugal, blah blah blah".  As I was looking over their work, I realized that one of the major conceptual problems is that a true understanding of why this works involves a tale of two fake forces:

Fake force #1: 

Gravity

You don't actually ever feel the force of gravity pulling you down into the ground (contrary to what I teach my student to draw on free body diagrams!).  Rather, you only feel the normal force pushing up on you (the opposite direction!).  This was one of Einstein's key insights in revealing the General Theory of Relativity.  Since gravity is really just an alteration of your inertial path ("warping of spacetime"), it is not a force. What you feel is the ground pushing up against your inertial path so you assume something is pulling down on you.

Fake force #2:

Centrifugal forces

You don't actually ever feel a force pulling you out of a circle (or a turn).  Rather you feel a force directed towards the center of the arc of the circle of the turn you are making (the opposite direction!).  The force is required to keep you from following your inertial path (which is tangent to the circle).   Since you feel the force pushing inwards on you against your inertial path, you assume something is pulling outward on you.

----

So, "artificial gravity" on space stations (accomplished by walking on the inside of the outer surface of rotation) is really the swapping of one fake force for another.  Either way, what you feel is a force on your feet preventing your from following your inertial path (the one you would take without any forces).

According to Einstein, we've been experiencing gravity as an upward acceleration on our feet our entire lives.  So, if you stand on the inside of a rotating surface, a 9.8 m/s/s centripetal acceleration to keep you going in a circle will substitute quite nicely for a gravitational field of 9.8 N/kg.  In one case we are accelerating inward to curve through space and in the other we are accelerating upward to curve through time.

The movie we were discussing was "Interstellar"

"If a person falls freely, he will not feel his own weight" - Einstein's 'happiest thought'