Why can't visible light travel through solid objects?

[Saeros]

[bimgx=400]http://www.optics.arizona.edu/Nofziger/UNVR195a/Class12/EMspectrum1.gif[/bimgx]

Why is it that the range of visible light on the electromagnetic spectrum cannot travel through objects, even though other forms of electromagntic radiation (both of a smaller and a larger wavelength (which i think is kind of weird)) can travel through objects? In fact, as the wavelength of the radiation increases or decreases away from visible light, it seems to gradually be able to travel through denser objects. For instance, ultraviolet rays cannot travel through solid objects, but gamma rays can, and infrared rays cannot travel through solid objects, but AM waves can (i think... ). Why is that?

 

[Cognisant]

You've never put your thumb over a touch?

Visible light can pass through solid objects, just not very well.

 

[Saeros]

You've never put your thumb over a touch?

Visible light can pass through solid objects, just not very well.

Good point. That didn't occur to when I wrote the post . The second part of my question was: why is it that the ability for electromagnetic radiation to travel through objects improves whether the wavelength increases or decreases. It's almost like the ability for electromagnetic radiation to pass through objects decreases as it moves towards the center of the spectrum. Why is that?

 

[Thaklaar]

Short answer - Long wavelength photons interact weakly with most matter (well, most terrestrial matter). Very high-energy photons (x and gamma) interact strongly with matter, but are energetic enough to tunnel through it. Visible light interacts with a lot of matter (not all, or we wouldn't have windows), but is not energetic enough to tunnel very far through it.

Long answer - I don't have the math for the long answer.

 

[Vrecknidj]

Think backwards.

It just so happens that some wavelengths in that whole spectrum happen to be able to reflect off of quite a bit of terrestrial matter. And, because that's the stuff that does, that's the stuff that eyes have evolved to see.

Dave

 

[Kuu]

there's lots of materials that are transparent or translucent to visible light... and ultraviolet and infrared as well...

That's why they sell specially coated anti-UV glass for windows and glasses and camera filters...

Hmm actually all camera sensors have an IR filter built in because...

the devices that allow you to see thru clothes (those that caused some controversy when they started using them in airports) are based on infrared wavelengths... fun stuff.


I think thaklaar's answer is not entirely correct (but hey, I'm no optics expert)... I think it had to do with the molecular structure of the material more than the energy of the photons

 

[ohrtonz]

Think backwards.

It just so happens that some wavelengths in that whole spectrum happen to be able to reflect off of quite a bit of terrestrial matter. And, because that's the stuff that does, that's the stuff that eyes have evolved to see.

Dave

That's I am thinking. If it went through solid objects it wouldn't be bouncing back so we can see it. Though, the explanations as to why it bounces back instead... Well FM radio bounces... but yeah.

 

[Agent Intellect]

Waves outside of 400-750 nanometers (visible light) do not pass through everything - if they did, the ozone layer would be useless. Visible light reflects off of the materials we evolved to see (as is stated already), which if I recall is often materials with atoms containing d-orbitals in their valence shell (metals). Visible light doesn't reflect off of air on "normal" earth atmospheric conditions, though (which is a nitrogenous solution), so it doesn't reflect off from everything.

 

[fullerene]

I think it's similar to what Thaaklar said... but something about that strikes me as wrong. Tunnelling is a quantum-mechanical phenomenon... but to the best of my knowledge, light passing through solid matter wasn't ever used as evidence for QM, which most likely means that there's a classical explanation for it.

It's a shame, cause I'm taking a course in optics this semester... but this is bothering me (it's something I probably already ought to know), so I'm gonna poke around and see if I can find anything convincing online.

 

[walfin]

Visible light doesn't reflect off of air on "normal" earth atmospheric conditions, though (which is a nitrogenous solution), so it doesn't reflect off from everything.

Yeah. Think the ionosphere and shortwave radio. Light passes through that.

And light passes through glass, acrylic, plastics etc. For natural stuff - light passes through some crystals (though not always all light, sometimes only certain colours, i.e. frequencies).