Why Do Mirrors Flip Left & Right (but not up & down)?

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Genre: Science & Technology

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Shared December 6, 2019

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This video is about why words flip left & right (aka horizontally) in a mirror but not up & down (aka vertically). The answer has to do with specular reflection, mirrors being like windows into another world (alternate universes, just with in and out flipped!), and transparency of the things we write on.

Specular Reflection

PhysicsGirl video about mirrors

Fermat’s principle


Thomas-Fermi screening

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Created by Henry Reich


I know lots of people have made videos about this before, but I felt I still had something to add, so, well, here you go! Also, I'm working on a video about CP violation (aka mirror symmetry violation) in particle physics, so I've been thinking more about mirrors recently. That video should be out soon!

2 months ago | [YT] | 1,290

Ive Harzing

That transparant card you used really made it click for me!

2 months ago | [YT] | 4,472

aidan balac

I’ve seen a lot of videos attempting to explain the mirrors flipping images, and this is the best explanation I’ve ever seen

2 months ago | [YT] | 2,355

Lassie Vision

You took something really simple that I took for granted, and made me realise that actually, I know nothing at all. Well done. Flipping brilliant!

2 months ago | [YT] | 1,308

Ricardo alves

I feel like an idiot for not understanding how words are reflected earlier

2 months ago | [YT] | 321

Anton Larchey

I love it when things are so "trivial" that you don't even think about them, but are very interesting the second you start to study them.

2 months ago | [YT] | 595

Just Some Guy without a Mustache

Mirrors are really fascinating. I really needed some time reflecting on this topic.

2 months ago | [YT] | 655


Producing mirrors must be super fascinating and exciting

I could really see myself doing that

2 months ago | [YT] | 220


I died when i read the
= YOUR MOM in Norwegian

2 months ago | [YT] | 420


I want all physics textbooks to remove the stupid "lateral Inversion"

2 months ago | [YT] | 107

Jankie Hands

1:11 hide the pain Henry Reich

2 months ago | [YT] | 112

Alex Landherr

Made me reflect a lot...

I’ll see myself out.

2 months ago | [YT] | 126


I love the addition of transparencies! I knew that the "flipping" mirrors do is in "z" axis, but imagining it mentally is 10 times easier with your transparency idea. Excellent!

2 months ago | [YT] | 39


The way he says mirrors in the end sounds like Hermione Granger saying its leviosa not leviosar

2 months ago | [YT] | 79

Georg Plaz

This is so simple, I can't believe I have never figured it out myself. I feel very humbled 😂

2 months ago | [YT] | 31


Freaken hell, that smile perforated deep into my soul...

2 months ago | [YT] | 28

Master Therion

Whoa! This is a deep concept. I need some time to... reflect.

2 months ago | [YT] | 77

Aditya Mishra

This video makes me feel I've circled the youtube once, because years ago the first video i watched of Physics Girl was mirror flipping as well.

2 months ago | [YT] | 6

Shah Yawer

Feynman talks about this magic. Actually all that Feynman talks about is magic. Beautiful work, once again @minutephysics

2 months ago | [YT] | 48

Crucial Muzic

[2:23] When you come home and find food in your fridge

2 months ago | [YT] | 9