# Can you see the x through the hole? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [December 8, 2015, 10:09pm UTC](https://boards.straightdope.com/t/can-you-see-the-x-through-the-hole/739857 "2015-12-08T22:09:05Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![Mudshark](https://avatars.discourse-cdn.com/v4/letter/m/f04885/32.png) [@Mudshark](https://boards.straightdope.com/u/Mudshark)\ **Post date:** [December 9, 2015, 6:02am UTC](https://boards.straightdope.com/t/can-you-see-the-x-through-the-hole/739857/41 "2015-12-09T06:02:07Z")
Part of the x is visible. ---
**Author:** ![Half\_Man\_Half\_Wit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/half_man_half_wit/32/21766_2.png) [@Half\_Man\_Half\_Wit](https://boards.straightdope.com/u/Half_Man_Half_Wit)\ **Post date:** [December 9, 2015, 6:16am UTC](https://boards.straightdope.com/t/can-you-see-the-x-through-the-hole/739857/42 "2015-12-09T06:16:22Z")
Thanks to everyone taking the time creating a model of the object! So far, there seems to be a bit of a discrepancy between the poll answers and those in the thread, with a majority answering ‘yes’ here, while the poll shows a near-50/50 distribution. Furthermore, those answering ‘yes’ mostly seem to concur that something like the top third would be visible (although it’s probably easy to exclude that much more would be seen). > [@Fenris](#): > > I think the question would be better if it were rephrased “If you rotated the object, _should_ you be able to see the X through the hole” (assuming that’s what you’re asking). I kept looking at the hole and > > from the angle it’s positioned, of course you can’t. If you rotate it so you’re looking directly through the whole, yeah, you should be able to see the top part of the X. > I’m holding off on voting pending a comment on the rephrase of the OP’s question that I posted. 🙂 Then I guess ‘should’ would be the right phrasing. (English is not my first language.) But I don’t quite get why: to me, ‘could’ asks for whether there is a rotation such that I see the X, while ‘should’ would ask whether if I rotate, I can see the X. I should see that object if I rotated through some angle and some axis (such that I look into the right direction through the window), but I could see the object after some rotation (namely, if that rotation turns out to be the right one). What’s wrong about this intuition? ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [December 9, 2015, 9:36am UTC](https://boards.straightdope.com/t/can-you-see-the-x-through-the-hole/739857/43 "2015-12-09T09:36:42Z")
I can’t resist pointing out that I was the first one with the answer over in the other thread, and it was the correct answer as shown in some of the actual model photos shown here. I did it essentially by visualizing the ray-tracing from the top front edge of the hole to the top back edge of the block in front of the gap: It had a slope of -1/3 (over three [towards the back] and down one). Continuing from there to the face of the X block is another one over (toward the back) and thus, with a slope of -1/3, it is another 1/3 down. Thus, the top 1/3 of the block is visible. (I hadn’t taken into account the horizontal displacement of the hole from the gap.) ---
**Author:** ![HowSoonIsThen](https://avatars.discourse-cdn.com/v4/letter/h/e56c9b/32.png) [@HowSoonIsThen](https://boards.straightdope.com/u/HowSoonIsThen)\ **Post date:** [December 9, 2015, 10:12am UTC](https://boards.straightdope.com/t/can-you-see-the-x-through-the-hole/739857/44 "2015-12-09T10:12:11Z")
I’m stupid. I thought the question was “looking at that picture, is there an x in the hole?” Based on the other answers people gave (which I know I wasn’t supposed to read first but to hell with your rules) I’m guessing that’s wrong. ---
**Author:** ![kk\_fusion](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kk_fusion/32/15276_2.png) [@kk\_fusion](https://boards.straightdope.com/u/kk_fusion)\ **Post date:** [December 9, 2015, 10:33am UTC](https://boards.straightdope.com/t/can-you-see-the-x-through-the-hole/739857/45 "2015-12-09T10:33:13Z")
Without reading previous answers, my intuition is that the face with the X is at least partially visible. * * * And some raytracing in my head confirms: The line from the upper right corner of the X through the center of the inner right edge of the hole has a grade of less than 0.5 in either direction and can easily pass through. ---
**Author:** ![kk\_fusion](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kk_fusion/32/15276_2.png) [@kk\_fusion](https://boards.straightdope.com/u/kk_fusion)\ **Post date:** [December 9, 2015, 10:51am UTC](https://boards.straightdope.com/t/can-you-see-the-x-through-the-hole/739857/46 "2015-12-09T10:51:02Z")
Or, simpler: If you can see the top face of a block in the plane, you can see (part of) the back wall of the hole it leaves when removed. You can see the top faces in approximately a 90 degree field of view from the peephole. ---
**Author:** ![Rhythmdvl](https://avatars.discourse-cdn.com/v4/letter/r/85f322/32.png) [@Rhythmdvl](https://boards.straightdope.com/u/Rhythmdvl)\ **Post date:** [December 9, 2015, 11:33am UTC](https://boards.straightdope.com/t/can-you-see-the-x-through-the-hole/739857/47 "2015-12-09T11:33:39Z")
14 of you are close, but no one has taken the right approach yet. Keep looking at it as if was one of those cube-drawing flippy things. Of course something that is focused on “visual imagination” related to 3D space isn’t meant to be taken literally. Going about it by making models isn’t the right tack to take. In other words, you need to go back to the original and stare at it, blink, go cross-eyed, or whatever it takes to get the 2D image you visually imagine as a 3D representation to change orientation. Another way of seeing it is to print it out (or use two monitors) and try and see both at the same time. For what it’s worth, I had the tab open throughout the day and kept casually coming back to it until one time I came back and could see it. Persistence is key! Don’t worry; if it isn’t clear in a while I’ll come back and be more specific—but do try first! ---
**Author:** ![elfkin477](https://avatars.discourse-cdn.com/v4/letter/e/a9a28c/32.png) [@elfkin477](https://boards.straightdope.com/u/elfkin477)\ **Post date:** [December 9, 2015, 11:33am UTC](https://boards.straightdope.com/t/can-you-see-the-x-through-the-hole/739857/48 "2015-12-09T11:33:53Z")
Of course not. There is no hole. As Eyebrows of Doom said, we can see that the tops of blocks are white and there is no white in the bottom of the “hole” so it’s just a black brick. ---
**Author:** ![IvoryTowerDenizen](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ivorytowerdenizen/32/17937_2.png) [@IvoryTowerDenizen](https://boards.straightdope.com/u/IvoryTowerDenizen)\ **Post date:** [December 9, 2015, 11:48am UTC](https://boards.straightdope.com/t/can-you-see-the-x-through-the-hole/739857/49 "2015-12-09T11:48:34Z")
Moved to IMHO ---
**Author:** ![GuanoLad](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/guanolad/32/42_2.png) [@GuanoLad](https://boards.straightdope.com/u/GuanoLad)\ **Post date:** [December 9, 2015, 12:16pm UTC](https://boards.straightdope.com/t/can-you-see-the-x-through-the-hole/739857/50 "2015-12-09T12:16:43Z")
I picked No. I could certainly imagine how it might be Yes, but couldn’t fix it clearly enough in my mind to definitively choose it. I also [made a model](https://dl.dropboxusercontent.com/u/38786500/boxes.png). ---
**Author:** ![running\_coach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/running_coach/32/15836_2.png) [@running\_coach](https://boards.straightdope.com/u/running_coach)\ **Post date:** [December 9, 2015, 1:42pm UTC](https://boards.straightdope.com/t/can-you-see-the-x-through-the-hole/739857/51 "2015-12-09T13:42:47Z")
> [@elfkin477](#): > > \*\*Of course not. There is no hole. \*\*As Eyebrows of Doom said, we can see that the tops of blocks are white and there is no white in the bottom of the “hole” so it’s just a black brick. A much better phrasing: All in all, it’s just another brick in the wall. ---
**Author:** ![Bill\_Door](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@Bill\_Door](https://boards.straightdope.com/u/Bill_Door)\ **Post date:** [December 9, 2015, 2:00pm UTC](https://boards.straightdope.com/t/can-you-see-the-x-through-the-hole/739857/52 "2015-12-09T14:00:43Z")
I got it wrong. In all fairness, 50% of my eyes are strictly decorative, and binocular vision and depth perception are foreign concepts to me, so I was working with a handicap. ---
**Author:** ![CarnalK](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnalk/32/486_2.png) [@CarnalK](https://boards.straightdope.com/u/CarnalK)\ **Post date:** [December 9, 2015, 2:50pm UTC](https://boards.straightdope.com/t/can-you-see-the-x-through-the-hole/739857/53 "2015-12-09T14:50:53Z")
> [@Senegoid](#): > > (I hadn’t taken into account the horizontal displacement of the hole from the gap.) Wow. I totally missed that too. ---
**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:** [December 9, 2015, 2:57pm UTC](https://boards.straightdope.com/t/can-you-see-the-x-through-the-hole/739857/54 "2015-12-09T14:57:11Z")
Seems like I should be able to see the upper right corner of the X. ---
**Author:** ![Half\_Man\_Half\_Wit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/half_man_half_wit/32/21766_2.png) [@Half\_Man\_Half\_Wit](https://boards.straightdope.com/u/Half_Man_Half_Wit)\ **Post date:** [December 9, 2015, 3:00pm UTC](https://boards.straightdope.com/t/can-you-see-the-x-through-the-hole/739857/55 "2015-12-09T15:00:09Z")
> [@elfkin477](#): > > Of course not. There is no hole. As Eyebrows of Doom said, we can see that the tops of blocks are white and there is no white in the bottom of the “hole” so it’s just a black brick. Top of the brick below the hole is in the shadow, of course. ---
**Author:** ![Barkis\_is\_Willin](https://avatars.discourse-cdn.com/v4/letter/b/a183cd/32.png) [@Barkis\_is\_Willin](https://boards.straightdope.com/u/Barkis_is_Willin)\ **Post date:** [December 9, 2015, 3:08pm UTC](https://boards.straightdope.com/t/can-you-see-the-x-through-the-hole/739857/56 "2015-12-09T15:08:47Z")
My first thought was not from this angle, of course not. ---
**Author:** ![Hampshire](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hampshire/32/4887_2.png) [@Hampshire](https://boards.straightdope.com/u/Hampshire)\ **Post date:** [December 9, 2015, 3:41pm UTC](https://boards.straightdope.com/t/can-you-see-the-x-through-the-hole/739857/57 "2015-12-09T15:41:09Z")
> [@Senegoid](#): > > I can’t resist pointing out that I was the first one with the answer over in the other thread, and it was the correct answer as shown in some of the actual model photos shown here. > > I did it essentially by visualizing the ray-tracing from the top front edge of the hole to the top back edge of the block in front of the gap: It had a slope of -1/3 (over three [towards the back] and down one). Continuing from there to the face of the X block is another one over (toward the back) and thus, with a slope of -1/3, it is another 1/3 down. Thus, the top 1/3 of the block is visible. > > (I hadn’t taken into account the horizontal displacement of the hole from the gap.) I did essentially the same exercise. For the vertical displacement I made a crude side view. Start at point A go down 1 inch to point B. Go over 3 inches to point C, down one inch to point D, over 1 inch to point E, and back up 1 inch to point F. From there I drew a line from point A to point C (representing the sight line) and extended it to see where it would hit surface E-F. 1/3 the way down. I made a similar sketch for the horizontal displacement and the sight line hits 1/3 from the left of the X surface letting you see the right 2/3. You can see about 2/9 of the X surface. ---
**Author:** ![RedSwinglineOne](https://avatars.discourse-cdn.com/v4/letter/r/a9adbd/32.png) [@RedSwinglineOne](https://boards.straightdope.com/u/RedSwinglineOne)\ **Post date:** [December 9, 2015, 5:17pm UTC](https://boards.straightdope.com/t/can-you-see-the-x-through-the-hole/739857/58 "2015-12-09T17:17:23Z")
> [@pulykamell](#): > > Oh, almost forgot that I took pics: > > [Real-life set-up](http://www.pawinskiphotography.com/public/IMG_4291.JPG) Cool, but minus 1 point for not using an “X” block where the “X” is in the drawing. 🙂 ---
**Author:** ![Suburban\_Plankton](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/suburban_plankton/32/219_2.png) [@Suburban\_Plankton](https://boards.straightdope.com/u/Suburban_Plankton)\ **Post date:** [December 9, 2015, 5:29pm UTC](https://boards.straightdope.com/t/can-you-see-the-x-through-the-hole/739857/59 "2015-12-09T17:29:40Z")
I voted yes. If you consider the face of the cube with the X to consist of 9 sections, as 1 2 3 4 5 6 7 8 9 Then sections 2 and 3 should be visible, so the top right portion of the X should be visible ---
**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:** [December 9, 2015, 7:10pm UTC](https://boards.straightdope.com/t/can-you-see-the-x-through-the-hole/739857/60 "2015-12-09T19:10:04Z")
> [@RedSwinglineOne](#): > > Cool, but minus 1 point for not using an “X” block where the “X” is in the drawing. 🙂 I did actually think about that, then decided I couldn’t be arsed to find it. [Previous page](https://boards.straightdope.com/t/can-you-see-the-x-through-the-hole/739857.md?page=2) [Next page](https://boards.straightdope.com/t/can-you-see-the-x-through-the-hole/739857.md?page=4)