# "How does the mirror know the ball is there?" Oh my God **URL:** \ **Category:** The BBQ Pit\ **Created:** [August 28, 2023, 12:13pm UTC](https://boards.straightdope.com/t/how-does-the-mirror-know-the-ball-is-there-oh-my-god/989224 "2023-08-28T12:13:41Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![glowacks](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/glowacks/32/5548_2.png) [@glowacks](https://boards.straightdope.com/u/glowacks)\ **Post date:** [August 30, 2023, 12:18am UTC](https://boards.straightdope.com/t/how-does-the-mirror-know-the-ball-is-there-oh-my-god/989224/41 "2023-08-30T00:18:14Z")
> [@Briny\_Deep](#): > > Also a commonplace in my household, but we thought it was about a Thermos. I didn’t know it was from Andy Griffith, thanks for that! In my dad’s family, the “How do it know?” line about the Thermos came from (what I’ll call) a joke where various scientists of different nationalities proposed what the best invention ever was, and the scientist from the place you think the people are stupid says it’s the Thermos with the requisite lines. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [August 30, 2023, 7:49am UTC](https://boards.straightdope.com/t/how-does-the-mirror-know-the-ball-is-there-oh-my-god/989224/42 "2023-08-30T07:49:25Z")
> [@Exapno\_Mapcase](#): > > In this video it is literally one troll who posted dozens of times. Every other person got it and tried patiently explaining it to him. Rage Bait is the new clickbait. Post a video of something stupid - like asking a really weirdly ignorant question about a mirror, or cooking a steak by boiling it, or trying to open a pringles can at the wrong end, or just asserting something that is plainly wrong. Sit back and watch the views rattle up as the internet marvels at your stupidity, shares your stupidity (with a sense of superiority) amongst their social contacts, comments to try to educate you or belittle you (the algorithm literally doesn’t care which - all comments are engagement). ---
**Author:** ![pulykamell](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pulykamell/32/3166_2.png) [@pulykamell](https://boards.straightdope.com/u/pulykamell)\ **Post date:** [August 30, 2023, 12:23pm UTC](https://boards.straightdope.com/t/how-does-the-mirror-know-the-ball-is-there-oh-my-god/989224/43 "2023-08-30T12:23:24Z")
> [@Mangetout](#): > > Rage Bait is the new clickbait. Ah, is that the name for it? It ain’t nothing new either. It’s been going for years, that I can tell (probably from near the beginnings of YouTube, even), only now it seems people are catching on to it. There’s just so much stuff out there so obviously so stupid and so obviously intended to rile people up that I don’t understand why people take it sincerely. Yes, there’s actual idiots out there, but these idiots are trying too hard. (This particular video doesn’t seem that stupid to me, and it doesn’t seem intuitive. Like I said above, I originally couldn’t tell you why it works – though by now I’ve figured it out – and I took all sorts of science classes in high school and university.) ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [August 30, 2023, 2:39pm UTC](https://boards.straightdope.com/t/how-does-the-mirror-know-the-ball-is-there-oh-my-god/989224/44 "2023-08-30T14:39:29Z")
True - there’s nothing really new under the sun, but social media and in particular, short-form video has provided a fertile breeding ground for rage bait - I will not even click on a video that has ‘wait for it’ or ‘watch to the end’ in the thumbnail or title - usually, there is nothing to see and what you’re supposed to do is watch it several times without even realising it is cunningly looped, then comment on it, angrily demanding to know what the payoff is supposed to be (the video probably still looping and registering views while you engage in the comments). It works because the internet is also a place where people like to correct things they think are wrong. ---
**Author:** ![JRDelirious](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jrdelirious/32/9531_2.png) [@JRDelirious](https://boards.straightdope.com/u/JRDelirious)\ **Post date:** [August 30, 2023, 2:41pm UTC](https://boards.straightdope.com/t/how-does-the-mirror-know-the-ball-is-there-oh-my-god/989224/45 "2023-08-30T14:41:33Z")
> [@Mangetout](#): > > Rage Bait is the new clickbait. > > Post a video of something stupid - like asking a really weirdly ignorant question about a mirror, or cooking a steak by boiling it, or trying to open a pringles can at the wrong end, or just asserting something that is plainly wrong. > > Sit back and watch the views rattle up as the internet marvels at your stupidity A form of “Trolling Lite”, then? ---
**Author:** ![Little\_Nemo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/little_nemo/32/3120_2.png) [@Little\_Nemo](https://boards.straightdope.com/u/Little_Nemo)\ **Post date:** [August 30, 2023, 2:46pm UTC](https://boards.straightdope.com/t/how-does-the-mirror-know-the-ball-is-there-oh-my-god/989224/46 "2023-08-30T14:46:59Z")
> [@Dr.Strangelove](#): > > From an electromagnetic perspective, the virtual image really is there (assuming a perfect mirror, etc.). There’s no experiment you can perform with just photons that can distinguish a real image from a virtual mirrored image. Is this accurate? I’ve always thought that while a mirrored image is identical to a direct image to human perception, the two could be distinguished with accurate enough instruments. For example, some of the photons will be absorbed by the mirror. ---
**Author:** ![Horatius](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/horatius/32/3572_2.png) [@Horatius](https://boards.straightdope.com/u/Horatius)\ **Post date:** [August 30, 2023, 2:49pm UTC](https://boards.straightdope.com/t/how-does-the-mirror-know-the-ball-is-there-oh-my-god/989224/47 "2023-08-30T14:49:03Z")
> [@Little\_Nemo](#): > > For example, some of the photons will be absorbed by the mirror. Ah, yes, but he played the classic physics game of “assuming a perfect mirror”. In principle, there’s no way to distinguish the two, but in practice, you could compare the spectrum for both the real object and the mirror object, and conclude which was which. But physicists don’t play that! ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [August 30, 2023, 2:49pm UTC](https://boards.straightdope.com/t/how-does-the-mirror-know-the-ball-is-there-oh-my-god/989224/48 "2023-08-30T14:49:45Z")
Trolling for profit ---
**Author:** ![Little\_Nemo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/little_nemo/32/3120_2.png) [@Little\_Nemo](https://boards.straightdope.com/u/Little_Nemo)\ **Post date:** [August 30, 2023, 2:57pm UTC](https://boards.straightdope.com/t/how-does-the-mirror-know-the-ball-is-there-oh-my-god/989224/49 "2023-08-30T14:57:56Z")
> [@Horatius](#): > > Ah, yes, but he played the classic physics game of “assuming a perfect mirror”. > > In principle, there’s no way to distinguish the two, but in practice, you could compare the spectrum for both the real object and the mirror object, and conclude which was which. But physicists don’t play that! So in a direct image I look like myself but in a perfectly reflected image I look like a sphere. ---
**Author:** ![Horatius](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/horatius/32/3572_2.png) [@Horatius](https://boards.straightdope.com/u/Horatius)\ **Post date:** [August 30, 2023, 3:46pm UTC](https://boards.straightdope.com/t/how-does-the-mirror-know-the-ball-is-there-oh-my-god/989224/50 "2023-08-30T15:46:02Z")
Well, I didn’t want to body shame you, but… 😃 ---
**Author:** ![TroutMan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/troutman/32/6721_2.png) [@TroutMan](https://boards.straightdope.com/u/TroutMan)\ **Post date:** [August 30, 2023, 8:51pm UTC](https://boards.straightdope.com/t/how-does-the-mirror-know-the-ball-is-there-oh-my-god/989224/51 "2023-08-30T20:51:16Z")
> [@Mangetout](#): > > It works because the internet is also a place where people like to correct things they think are wrong. There’s a great post from a programmer saying (paraphrased) “when I need an answer to a programming question, I post it on StackExhange, then immediately log in with a different account and post an obscenely wrong answer. No one wants to help others, but they’ll fall all over themselves to correct someone else.” Also known as [Cunningham’s Law](https://en.wikipedia.org/wiki/Ward_Cunningham#%22Cunningham's_Law%22). ---
**Author:** ![RickJay](https://avatars.discourse-cdn.com/v4/letter/r/bb73d2/32.png) [@RickJay](https://boards.straightdope.com/u/RickJay)\ **Post date:** [August 31, 2023, 2:37am UTC](https://boards.straightdope.com/t/how-does-the-mirror-know-the-ball-is-there-oh-my-god/989224/52 "2023-08-31T02:37:13Z")
> [@Little\_Nemo](#): > > For example, some of the photons will be absorbed by the mirror. All mirrors absorb some of the light, and bathroom mirrors usually aren’t all that efficient, absorbing anywhere from two to ten percent of it, depending how much you paid for it. They can also have tiny imperfections, bends, etc. ---
**Author:** ![digs](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/digs/32/14889_2.png) [@digs](https://boards.straightdope.com/u/digs)\ **Post date:** [September 1, 2023, 10:07pm UTC](https://boards.straightdope.com/t/how-does-the-mirror-know-the-ball-is-there-oh-my-god/989224/53 "2023-09-01T22:07:45Z")
> [@Little\_Nemo](#): > > So in a direct image I look like myself but in a perfectly reflected image I look like a sphere. Ahh, you get dressed in front of a funhouse mirror, too, I see. We got our “PhunWithPhotonz” mirror (slimming version) from _[WayFair-To-Middling.com](http://WayFair-To-Middling.com)_ and it’s so good for my self-esteem! . > [@Mangetout](#): > > It works because the internet is also a place where people like to correct things they think are wrong. I think that should be “things _that_ they think are wrong.” ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [September 2, 2023, 11:03am UTC](https://boards.straightdope.com/t/how-does-the-mirror-know-the-ball-is-there-oh-my-god/989224/54 "2023-09-02T11:03:21Z")
Case in point ---
**Author:** ![pjd](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pjd/32/3009_2.png) [@pjd](https://boards.straightdope.com/u/pjd)\ **Post date:** [September 2, 2023, 11:51am UTC](https://boards.straightdope.com/t/how-does-the-mirror-know-the-ball-is-there-oh-my-god/989224/55 "2023-09-02T11:51:54Z")
So… the orange is the apple, right ? ---
**Author:** ![Sage\_Rat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sage_rat/32/399_2.png) [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)\ **Post date:** [September 2, 2023, 11:16pm UTC](https://boards.straightdope.com/t/how-does-the-mirror-know-the-ball-is-there-oh-my-god/989224/56 "2023-09-02T23:16:13Z")
> [@Left\_Hand\_of\_Dorkness](#): > > FWIW, I’m pretty strong with words, and I’m not bad with numbers, but my spatial intelligence is _rough_. What may seem intuitive or obvious to the OP is really hard for me to wrap my head around, even with diagrams; I accept that it works, but struggle to comprehend it intuitively. Could you bounce a ball to hit the object, without touching the paper? That’s how light do. ---
**Author:** ![Spectre\_of\_Pithecanthropus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spectre_of_pithecanthropus/32/12343_2.png) [@Spectre\_of\_Pithecanthropus](https://boards.straightdope.com/u/Spectre_of_Pithecanthropus)\ **Post date:** [September 11, 2023, 7:40pm UTC](https://boards.straightdope.com/t/how-does-the-mirror-know-the-ball-is-there-oh-my-god/989224/57 "2023-09-11T19:40:14Z")
I once saw a fascinating object at a science museum. It consisted of two round paraboloid sections, fastened rim to rim like two shallow bowls. There was a round cutout in the center of the top half, and the inner surfaces were all reflective, like the mirror of a reflecting telescope. If you place a small object, say a die or game piece from a board game, in the center of the bottom “dish”, you will see a perfect 3D image of the object that appears to be resting directly _above and outside_ the object. If some people can’t understand how an ordinary mirror works, then what would this thing do to their little minds? ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [September 11, 2023, 7:52pm UTC](https://boards.straightdope.com/t/how-does-the-mirror-know-the-ball-is-there-oh-my-god/989224/58 "2023-09-11T19:52:42Z")
You can get those devices fairly cheaply (like \<$20). Search for “mirascope”. They are pretty neat. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [September 11, 2023, 7:56pm UTC](https://boards.straightdope.com/t/how-does-the-mirror-know-the-ball-is-there-oh-my-god/989224/59 "2023-09-11T19:56:13Z")
There was an arcade ‘game’ made with that principle. There was no actual object, a video of an animated figure would appear to hover above a table. One game using the effect was called Time Traveler. It was often called a hologram but was not really. ---
**Author:** ![Spectre\_of\_Pithecanthropus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spectre_of_pithecanthropus/32/12343_2.png) [@Spectre\_of\_Pithecanthropus](https://boards.straightdope.com/u/Spectre_of_Pithecanthropus)\ **Post date:** [September 11, 2023, 7:58pm UTC](https://boards.straightdope.com/t/how-does-the-mirror-know-the-ball-is-there-oh-my-god/989224/60 "2023-09-11T19:58:31Z")
> [@Dr.Strangelove](#): > > You can get those devices fairly cheaply (like \<$20). Search for “mirascope”. They are pretty neat. I wonder now if larger versions of this are ever used in stage magic. ISTM it ought to be very easy to make a large object vanish when the real object was never in view of the audience at all. [Previous page](https://boards.straightdope.com/t/how-does-the-mirror-know-the-ball-is-there-oh-my-god/989224.md?page=2) [Next page](https://boards.straightdope.com/t/how-does-the-mirror-know-the-ball-is-there-oh-my-god/989224.md?page=4)