How To Bend Light Using Just Your Finger

↓↓↓ More info and sources below ↓↓↓

The other day I got bored and noticed this weird thing happened when I held my finger up to my eye, so I had to science it and figure it out! Let me know if you try these light-bending experiments too, especially that last one that I can’t quite explain yet…

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It’s Okay To Be Smart is hosted by Joe Hanson, Ph.D.
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[besmart]

The best wizards are scientists.

Try these for yourself and tell me what you see! Think you can explain the last trick? I'm interested to hear what you think…

[ivanbolatti]

I love what you did with #3. You didn't just repeat what's in textbooks. You questioned it. You are a true scientist.

[binky]

1:46 For the next experiment close one eye and look at something bright thats distant

Me: how about the sun?

Joe: *NEVER LOOK AT THE SUN*

[FortyTwo]

Hats off to your creative content! We hope that we will get this good in future!

[humanbutterfly]

For some reason when I just looked at picture with butterfly I thought it would say “Stay Ridiculous”.

[tanishq]

Am I the only one who did all of these things before( accidently/outta nowhere) and wondered why it happened.

[KQEDDeepLook]

TIL about the Shadow Blister Effect - always wondered how this worked. Many thanks!

[Subparanon]

Been doing this since I was a kid. You forgot the most useful aspect of using your fingers to bend light, eyeglasses. You know how when you step down the aperture of a camera lens, it brings more of an image into focus? You can do the same thing with your fingers. If your eyeglasses aren't within reach, and you need to sharpen your vision, you can hold two fingers close to your eye and look between them, as you bring the fingers close together, just before they touch, you are blocking most of the light that is arriving off axis, IE the "blur" leaving a narrow, and SHARP slit of light that you can then easily read text sharply with. It also works with just one finger, if you look out past the edge of it, objects near the edge will become sharper.

2:24 No, not a wizard yet. Four more years. :D

[it_was_my_cat]

I think I can explain the last trick.
If you make a pinhole (for example with your fingers) and look through it against a plain bright background, you can see a weird pattern emerge. It has spots and smudges in it. This may be caused by imperfections on your cornea and in your lens and vitreous/ aqeous humour. I'm not sure what causes the pattern, but it looks organic so that's my best guess. So, when you look through a slit, you're basically seeing this image repeated in a line. This causes the spots and smudges to be stretched out along the slit, making "lines" appear. Idk this is just my first guessplanation based off of about 2 minutes of playing around.

EDIT: Ok, I'm almost certain this is the correct explanation, since after blinking the pattern changes. This means that the pattern is a shadow of imperfections on your cornea, exactly where the spot of light passes through. Also, I tried gradually reducing the slit to a pinhole and sure enough I saw a single image of the pattern emerge. When I let the pinhole expand back into a slit again, I saw the single image get repeated continuously into the line pattern.

[XGames-]

I asked this in September in one of your videos. Probably just skipped over it.

[RyanMartinez]

Ohhhh... This whole time I thought my eyesight was bad. Now I know everybody does this.

[ScottJPowers]

as I see it, one line between your fingers is caused by the edges of the penumbra overlapping but because it is out of focus, it makes multiple, slightly off center, images on your retina so you see the line caused by the overlapping of the edges of the penumbra multiple times. (copyright Scott Jeffrey Powers)

[JosiGold]

As some others have pointed out, I think its just the penumbra of the two fingers interacting with each other. If you start with your fingers opened up and slowly move them together you can see the two different penumbras from each finger merge and create the line patterns

[Jess-gsgv]

I read the title as “Can you bend finger with your light?”

[Vistico]

I still have a memory of doing the finger pinch one when I was in first grade, bored in an assembly using the slit of sunlight coming from a door. I didn't know what it meant but I thought it neat that such an effect could happen and how precisely you had to do it for the effect to become visible

[longliveplanetawesome]

This is so cool. I was just doing my physics homework when this video was posted. The chapter I was reading was about light.

[alanhere]

Thanks. I've noticed this demonstrably hand light bending effect too as a young child. And boredom is soo important to progress, the alternative is exhaustively sneery certainty about inefficiency and arrogance.

[moamin.aljaro]

that moment when you realize that you're a nerd when you laugh at science jokes

[YassinElMohtadi]

0:16 We should ask captain disillusion to explain how did you do this trick