Why cant light shine through solids?

[Elite Engineer]

Pressurized hydrogen is known to leak through its container due to its incredibly small size. Why is it that photons being much, much smaller than hydrogen atoms cannot shine or "leak through" solids/ containers?

 

Just for comparison of size between hydrogen atoms and photons:

 

hydrogen atom mass: <1.0 x 10^-26g

 

photon mass: <1.0 x 10^-35g

-EE

[ACG52]

Because photons are absorbed by electrons. Hydrogen atoms are not absorbed by anything.

[EdEarl]

I like this question. Of course, photons do go through glass and some other solids. Moreover, some wavelengths of light cannot penetrate some liquids or gases, and cannot penetrate plasmas, iirc.

 

Why does light penetrate some materials but not others? Perhaps this question should be in another thread. If so, a moderator will move it.

Edited June 9, 2013 by EdEarl

[swansont]

Light does shine through solids. Glass and certain plastics are two examples. The key is not having resonant absorption lines in the visible region of the spectrum and that's unusual, so only a few materials are transparent.

 

Hydrogen leaks through materials but that's by diffusion — it doesn't just pass straight through unimpeded. They bounce off of atoms and change direction but eventually make it through, and the surface of the container is continually bombarded by the atoms. That's not what photons are doing in a transparent material. They're passing through without changing direction or energy.

[CaptainPanic]

An example where light can pass through a solid by 'diffusion' (note, I use this term loosely) is paper. Some photons get absorbed, but some others just bounce off a number of fibres and come out the other end. So, while some light does pass through the paper, you cannot see anything sharp through it. It's all diffuse.

[Moontanman]

Light does shine through solids. Glass and certain plastics are two examples. The key is not having resonant absorption lines in the visible region of the spectrum and that's unusual, so only a few materials are transparent.

 

Hydrogen leaks through materials but that's by diffusion — it doesn't just pass straight through unimpeded. They bounce off of atoms and change direction but eventually make it through, and the surface of the container is continually bombarded by the atoms. That's not what photons are doing in a transparent material. They're passing through without changing direction or energy.

 

A prism? Photons do change direction and they slow down, light passing through a diamond slows down to less than half speed...

[swansont]

A prism? Photons do change direction and they slow down, light passing through a diamond slows down to less than half speed...

 

Fair enough. That direction change is happening at the surface, though, not through the material (and the photons don't slow down, but that's a different discussion)