The specific gravity of cold-press coffee


Okay, a bit of a misleading title, but I like it nonetheless.

I just had a minor bit of unpleasant SIWOTI, only in meatspace instead of On The Internet. I don’t think I handled it entirely appropriately but that’s mostly because as a nerd, these things do matter to me. But interacting with other people also matters to me.

Caribou Coffee is a local answer to Starbucks that falls about halfway between Tim Horton’s and Starbucks on the scale of fancy-fancy frou-frou (which is a scalar value, obviously). They have a trivia question on a chalkboard next to their menu every day, and getting it right will knock ten cents off your order. It’s not a big deal, but it’s a fun little thing. Today’s question was: “What is Mars’ gravitational pull (relative to Earth’s)?”

Being an amateur space and sci-fi junkie, I actually knew this answer off the top of my head — about one third, since Mars’ is 3.7-ish m/s2 (by my recollection), and Earth’s is 9.8. I said so while placing my order, and was told that I was wrong — that Mars’ is about 40% more.

I kinda balked a little, didn’t want to fight much but I did say that I thought she was wrong, and what the numbers were by my recollection. The order taker’s response was to say that they were given that answer, that they “liked astrology but doesn’t know a lot about it”. I let that comment slide, though I had to bite my tongue hard — instead, I suggested that others might argue with them and that they should be prepared to have that fight. I was told that I was the only one to have answered the question in the past two days that the trivia was up.

People shouldn’t need to know all these little trivia facts off the top of their heads, but they should at least Google them. I did so on my phone on the way to my office, and found that Google gave the exact gravity of 3.711m/s2 for Mars, and the first link said Mars’ gravity was “about 62% less than Earth’s”. Since that’s close to the inverse of 40%, I can’t help but think the correct answer just got mangled on its way to the baristas in a game of telephone, all the other wrongness here notwithstanding.

I came off as a jackass, trying to argue with a barista over ten cents. I don’t like that fact. But I also don’t like that people with the right answer would be given a “correct” answer that doesn’t even pass the smell test.

How would you have dealt with this?

Comments

  1. says

    If they’re going to have some “official” trivia thing, they need to have someone who knows what they’re doing fact-check it. Being factually wrong and sticking to it as they are really doesn’t look good for a company. Better to let someone at the corporate office know rather than try to argue with someone who really doesn’t have a clue.

  2. says

    At the very least you could have given us the specific gravity of the coffee!! I’m disappointed.
     
     
    Surely their mistake is all part of that general dislike of Science on the part of many Americans.
    — ‘Astrology’!! If she said that she was maybe thinking of the gravitational pull of Mars relative to Earth’s on a body that was actually on the Earth!! Isn’t that how Astrology works?

  3. Who Cares says

    How I would react on an exchange like that?
    I have a really bad habit, really bad, with relation to stuff like this. It boils down to I’m not wrong and I’ll continue to argue with you until you admit your mistake if needed. Takes a bit getting used to, my first fight with my girlfriend was about me not supporting her in public but telling her why she was wrong in front of everyone.
    In this case I’d probably do the math to explain why my answer is correct.

  4. sbuczkowski says

    As a physicist and educator, I’d have been inclined to show them the math. VERY inclined. “It’s the answer they gave us (and I didn’t want to be bothered thinking about it)”, is a response that just drives me nuts.

  5. sinned34 says

    Forget about the specific gravity of crappy coffee. I want to hear about the final gravity of that coffee stout you made, and how it turned out!

  6. John Horstman says

    I think attempting to correct the mistake is the proper course. Misinformation like this has a way of becoming widespread, rarely, but sometimes devastatingly. The truth matters. The misinformation reflected in this poll, for example, had to start somewhere, and it was likely spread to (sometimes) majorities of the population through (in part) things like this trivia quiz. It’s not ALL (intentionally?) bad religious textbooks for homeschoolers or Bob Jones University that creates and spreads misinformation. Perhaps one of the baristas is an aspiring screenwriter, and this “fact” makes it into a popular TV show four years from now. Perhaps this leads to such widespread misinformation that outcry from a misinformed public derails a Mars exploration project, where laypeople insist they know better than the experts (THIS happens all the time) due in part to this “knowledge”. It’s unlikely, but since it’s almost impossible to predict beforehand which tiny instances like this are going to go full-on Butterfly Effect, I think we should address this where we see it. Discourse plays a large role in dictating policy (and people’s behavior more generally), and a discourse is made up of countless individual interactions like this.

  7. John Horstman says

    Oh, I though I should add a non-hypothetical example of misinformation going disastrously wrong: anti-vaxxers prompting a resurgence of diseases we had eliminated in the US decades ago. ‘Nuff said.

  8. CompulsoryAccount7746, Sky Captain says

    “liked astrology but doesn’t know a lot about it”.

    *twitch*
     

    I […] was told that I was wrong – that Mars’ is about 40% more.

    I can’t help but think the correct answer just got mangled on its way to the baristas in a game of telephone

    If someone googled “Mars gravity Earth”, they would have seen “40% of Earth’s gravity”.

  9. Daniel Schealler says

    I think I would have handled it by using convincing logic (note: not the same as good logic or the best logic).

    I would have said: You can see in those rover pictures that Mars has a thin atmosphere. All the air floated away, so it must have weaker gravity than Earth. If the gravity was stronger than Earth, Mars would have a heavier atmosphere and the rovers wouldn’t need such big parachutes.

    Yes, there are flaws in this line of argument. But I think people can probably grok it a bit easier.

    I’d follow this up with: You sure it wasn’t the other way around, like Earth is 40% stronger than Mars and someone just wrote it down wrong or something?

    Basically make it so that it’s not the barrista’s fault, and explaining it in a way that you don’t have to have been a good physics student in highschool to understand.

    I would’ve done it with a smile and a friendly chuckle too, and finished up with a ‘ah well, it’s not important’ shrug at the end.

  10. robb says

    the question is very poorly worded and has built in assumptions that are not stated explicitly.

    “pull of gravity” is ambiguous. do they mean the acceleration at the surface due to gravity or the force of gravity at the surface. one is an acceleration, the other a force with different units. the force of gravity varies as an inverse square of the distance, so you need to state at what distance (the assumption is at the surface). if you pick the center of each planet, the force and acceleration due to gravity are both zero–equal! at infinity they are both zero too. in between gives in between values.

    another consideration would be do they mean the force of mars gravity on the earth compared to the force of earth gravity on mars? if so, those are equal too.

    the question is not clear and with deeper thinking gives many interesting answers!

  11. Daniel Schealler says

    @rturpin #17

    “How would you have dealt with this?”

    “Look, I was there just last week…”

    Ha! ^_^

  12. adamo says

    Since I tend to wear a company uniform when out and about, I’m a bit stifled when it comes to trying to argue facts with somebody who has no clue. But hey, I make better, cheaper coffee at home anyway, so if they want to play a game only halfway, as in “we’re right and I don’t know/care why”, they should need my business why?

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