Light coming back
Why Can You See Yourself?
Light bounces off surfaces at a predictable angle. Your face rides that bounce.
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Step 1 of 5
Light bounces like a ball off a wall.
A ray arriving at 30 degrees leaves at 30 degrees on the other side of straight-on. Angle in equals angle out — always.
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Step 2 of 5
Your face is scattering light everywhere.
Light from the room lands on you and bounces off in all directions. Some of it heads toward the mirror.
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Step 3 of 5
The mirror sends it back organised.
Because the surface is flat and smooth, every ray keeps its neighbours in order. The bounce preserves the whole pattern of the picture.
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Step 4 of 5
Your brain assumes light travels straight.
It has no way to know the light bounced. It traces the rays back in straight lines and concludes there is a copy of you behind the glass.
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Step 5 of 5
Which is why you look as far behind as you are in front.
Stand a metre from a mirror and your reflection sits a metre behind it — a two metre gap. That is why you must step back to see all of yourself.
A mirror only needs to be half your height to show all of you — and it works from any distance.
The short version
Reflection is an orderly bounce, and your brain reads the returning rays as an object behind the glass.
Try it yourself
Mark your height on a mirror with tape at the top of your reflection. It sits at eye level, not head level — half your height is enough.
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