Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Noel Eastwood on 13/05/2008 08:46:43
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Noel Eastwood asked the Naked Scientists:
Hi Chris and crew,
Is VISIBLE light really visible because all i can see are objects and nothing in-between...so can you please define Visible?
Noel eastwood
Menzies creek...
Melbourne, Australia
What do you think?
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Hi Noel
'Visible' means the range of electromagnetic wavelengths to which your eye responds.
If you can 'see' an object, the light must be getting into your eyes from that object.
The light which enters your eye starts its journey somewhere. which is either a luminous object or an object which is reflecting light. If you were to be seeing anything in between then there would have to be an 'object', which could be some dust particles or a region of glowing gas (less likely unless you are talking about seeing things in space). In any case, the light would be coming from 'something'.
Your brain cannot know anything about the origin of the light except the direction it entered your eye. Mirrors, mirages or lenses which alter the path of light will completely fool it.
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Visible light is light, which when it hits the retina at the back of your eye your retina can detect and send a signal to your brain. If infra red light hits your retina then no signal will be sent.
The way you see things is that light is emitted from a source such as a light bulb, it then travels in straight lines until it hits something and bounces off some colours but not others. If some of this light hits your eyes they can tell what direction it came from, so you know there is something that colour in that direction
[diagram=340_0]
So our eyes actually detect the light from an object no the object itself. Light doesn't interact with other light (or air very strongly) so no light bounces off these so you can't see them