How exciting! (and a thought)

My idea blossomed into a forum

Ok I do have a question though. Well, its more of pondering.

When does 'light' stop being 'light'?

We all know that visible light is part of the electromagnetic spectrum. But, all ANYTHING in the spectrum is, is a wave. So, below 400nm you get ultraviolet and beyond that is x-ray coming in at around .5nm and beyond that gamma rays which are smaller than .0005nm. The same is true for the other end of the spectrum, going from infrared to microwave to radio.

So my question is when does light cease to be light? Is it arbitrary? In theory we could have gamma and x-ray diodes.

Thoughts?

What do you mean 'when does light stop being light'? It's all the same thing!

'light' just refers to the visible part of electromagnetic radiation. It's all electromagnetic radiation; x-rays, gamma rays, green light, microwaves, IR, etc. ... all the same thing but with different wavelengths.

So yes, in theory gamma ray diodes and x-ray diodes are possible. But in practice, we're not there yet

Instead of goggles, we'll need body suits!

murudai, i understand what he's trying to say;


lets start by defining LIGHT:

Light, or visible light, is electromagnetic radiation of a wavelength that is visible to the human eye (about 400[ch8211]700 nm). In a scientific context, the word light is sometimes used to refer to the entire electromagnetic spectrum. Moreover, in optics, the term "visible light" refers to electromagnetic radiation with wavelengths of ~300 nm (near UV) through ~1400 nm (near infrared).


so, as you just read, it depends on the analyst



[edit]EDIT: YES, it is from Wikipedia, i didnt know the PERFECT definition of light, SO WHAT? talk about productive comments.[/edit]

nikokapo said:

so, as you just read, it depends on the analyst

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That's why we replicate other's work.

Peace,
dave

yes but IR is also 'light' even though it's beyond the visible spectrum. That's why I think its just a texbook definition, as there is no definite answer because if you get down to the meat and potatoes of it; its all the same thing.

As nikokapo points out, it's all in the definition. In normal speaking language, light is radiation with wavelengths that can be observed by the human eye. If you define light scientifically, I guess it can refer to the entire electromagnetic spectrum. But then again, I'm yet to meet the scientist who classifies gamma radiation or an FM broadcast as "light".

Ah, okay. I think I know what you mean.

Well, most people I know just refer to 'light' as what you can see. Everything else is generically referred electromagnetic radiation. But really, 'light' isn't a strict scientific term. You could call x-rays light too.

I think people just refer to 'light' as only the visible part because of how the word 'light' is used in language:

"That torch has a very strong bright light!"
"Ow! Quit shining that light in my eyes!"
"The lighting is perfect for this photo shoot."

The word 'light' is associated with stuff we can see.

Petrovski said:

But then again, I'm yet to meet the scientist who classifies gamma radiation or an FM broadcast as "light".

Click to expand...

hahah, 100% agreed! By definition it is possible, but it's not very practical.

But isn't light made of photons also ? or does it mean microwaves and radio waves are made of photons too :-/ :-?

How does far IR and UV react to mirrors?

What about gamma or X-rays?

A laser pretty much works off of mirrors right?  

So if the gamma or X-ray contain photons capable of reflecting from some sort of mirror (reflective material) of which the frequency of light bounces off and not pass through, then it may be possible for lasers of a different universe of spectrums.  The problem with these super short wavelenghts is that they are very difficult to harvest/contain since they pass through many massive solids.

Anyway, these are just my thoughts and nothing more.  

Microwaves were invented in attempt to establish communications correct?  

erm..

idk about microwaves,

but if they are photons, they should "bounce" off of mirrors..but at that wavelength i think they would just go through them


also, why do they make you take off every metal thing you have on you when you get a radiography?

I think the definition also has to do with the properties (as well as visibility to human eyes) of the em radiation and how such radiation interacts with the atoms in matter.

What is declared as "visible" light (what we see + near IR and near UV) behaves in a similar manner - it will reflect off mirrors and pass thru substances that are transparent to our eyes, like glass and plastic.

Far-IR and UV behave less like "light" as they won't pass thru transparent substances like glass but they are still different enough from X-rays and microwaves that they are still considered to be light and when in coherent form as laser radiation.

Microwaves and x-rays (and also gamma rays and radio waves) can't be created or focused in a laser-like fashion (though there is the MASER, but that's a whole different thing from a laser, and also experimental X-ray lasers, which really ought to be called XASERS!), at least not very easily.

It's an interesting thing to explore - the sorts of interactions that take place between em radiation and matter as wavelength and frequency change.

For instance, low-frequency radio waves pass right thru most all substances (including living flesh) because the waves are so long that they don't interact (or disturb) the atoms in most elements.

X-rays, however, also pass thru most substances, but with living flesh, there are still enough waves/photons that do strike cells, which damage the cells and can lead up to cancer. Or if the radiation is intense enough, cell death is the end result, also known as radiation poisoning.

Of course you can then divide the em spectrum by ionizing and non-ionizing radiation.

paper183 said:

But isn't light made of photons also ? or does it mean microwaves and radio waves are made of photons too  :-/ :-?

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You got it.

but if they are photons, they should "bounce" off of mirrors..but at that wavelength i think they would just go through them

Click to expand...

What we call "mirrors" are only reflective to wavelengths with similar propreties to visible light (from near UV to near IR).You need other kinds of mirrors and lenses for other wavelengths, like ZnSe lenses for a CO[sub]2[/sub] laser beam.Regular glass would just crack or melt with enough power because it absorbs that wavelength rather than passing and refracting it.

Switchez-b1tchez said:

What we call "mirrors" are only reflective to wavelengths with similar propreties to visible light (from near UV to near IR).You need other kinds of mirrors and lenses for other wavelengths, like ZnSe lenses for a CO[sub]2[/sub] laser beam.Regular glass would just crack or melt with enough power because it absorbs that wavelength rather than passing and refracting it.

Click to expand...

AWESOME!
i didnt know there were mirrors for different wavelengths :O

if you want an example of some simple mirrors for different wavelengths, look up 'hot' and 'cold' mirrors at edmunds optics. the hot mirrors reflect IR and the cold mirrors reflect visible.