Скачать или смотреть GLASS Shouldn't Let Light Through — Feynman Explains Why It Does

Glass is a solid.

Solids block light.

So why can you see through your window?

At first glance, transparency feels obvious — almost boring. Of course glass is transparent.

But from the standpoint of physics, it absolutely shouldn’t be.

In this video, we unpack one of the most deceptively simple questions in science: why does glass let light through? Following the path laid out in Richard Feynman’s explanations from QED: The Strange Theory of Light and Matter and The Feynman Lectures on Physics, we build the answer layer by layer — from classical waves to quantum mechanics.

Classically, light is an electromagnetic wave.
Electrons in matter respond to electric fields.
Oscillating electrons should re-radiate light in all directions.

So why doesn’t every solid behave like a mirror?

The answer lives in the quantum world.

You’ll discover:

• Why the classical picture predicts opacity
• Why the “tiny holes in glass” idea is completely wrong
• The truth about the myth that glass is a slow-moving liquid
• Why electrons can only absorb very specific energies
• What a band gap is — and why it makes transparency possible
• Why glass blocks ultraviolet but passes visible light
• Why metals reflect instead of transmit
• How Feynman’s probability arrows explain reflection and transmission
• How tiny impurities turn clear glass into colored glass

The key insight is unsettlingly simple:

Light can only be absorbed if it matches an allowed energy jump inside the material.

Visible light doesn’t have the right energy to excite electrons across glass’s band gap — so it passes through.

Not because the atoms aren’t there.
Not because the light ignores them.
But because quantum mechanics forbids the interaction.

Your window is not empty.
It’s a quantum filter.

And here’s the deeper twist:

If human eyes evolved to detect ultraviolet instead of visible light, glass would look opaque. The world you call “transparent” is partly a consequence of the detector you happen to be.

By the end, you won’t just understand glass.
You’ll see how quantum rules quietly shape what counts as visible reality.

💬 After watching, consider this:
What other “obvious” properties of the world might depend entirely on how your senses are tuned?

👍 Like if this changed how you look at your window
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⚠️ DISCLAIMER
This video is AI-generated (synthetic voice and visuals). It is an original, fictional lecture inspired by Richard Feynman’s public teaching style and ideas. It is not an authentic recording, endorsement, or statement by Richard Feynman or his estate. Any resemblance is for educational and creative purposes only.