Question on vision.

[Kermit]

Let's say that there was an object that can't be seen in the visible part of the electromagnetic spectrum. How would it appear? Black? Invisible?

[ydoaPs]

it depends on if the light at that frequency is absorbed or passes through said object.

[Kyrisch]

Since we perceive the objects around us indirectly, through the perception of light bouncing off the objects, if no light in the visible spectrum bounces off an object, it would appear invisible.

[Kermit]

Thanks.

 

And could it be possible if life evolved orbitting a star that emits most of its radiation in other parts of the spectrum, like radio or ultraviolet, the organisms would be able to see in those frequencies?

[ydoaPs]

Since we perceive the objects around us indirectly, through the perception of light bouncing off the objects, if no light in the visible spectrum bounces off an object, it would appear invisible.

not if it is absorbed...then it is black

[Kyrisch]

True, absolutely true, YDNPS, and in response to Kermit:

It is my supposition that the Universe in not only queerer than we imagine, it is queerer than we CAN imagine.

[ydoaPs]

Thanks.

 

And could it be possible if life evolved orbitting a star that emits most of its radiation in other parts of the spectrum' date=' like radio or ultraviolet, the organisms would be able to see in those frequencies?[/quote']

iirc, bees and some snakes can see other parts of the spectrum

[AzurePhoenix]

As can mantis shrimp, which can see three wavelengths of ultraviolet light. Kites use UV light to trace mouse urine, and parrots and certain fish have patterns only visible in the uv. So, as long as it's useful, the abiliity could evolve in any system where any uv or infra lightwas produced, basically all of them.

 

EDIT: That's just Earth evolution, with Earth eyes, other courses of evolution might easily allow vision across higher and lower wavelengths. Or some other perception entirely.

[insane_alien]

Gold fish can see the flashes from your remote control. did you know you can convert your webcam to pick up infared only? try this its quite cool http://homepage.ntlworld.com/geoff.johnson2/IR/

[mezarashi]

Let's say that there was an object that can't be seen in the visible part of the electromagnetic spectrum. How would it appear? Black? Invisible?

 

Firstly, as far as I know, there are no real worldly objects that do not "respond" to the visible spectrum. An object is visible when it absorbs and then re-emits photons incident on its surface.

 

Another point, taking for example the perfect black-body, a body that absorbs everything and emits nothing as a response. The term black body is a bit misleading, as we know, anything that has a temperature will radiate electromagnetic waves. So even if it did absorb all radiation, it would be forced to radiate some light as predicted by the Stephan-Boltzmann law. Because of this, whether it will appear black in the visible spectrum will also depend on its temperature.

 

 

Gold fish can see the flashes from your remote control. did you know you can convert your webcam to pick up infared only? try this its quite cool http://homepage.ntlworld.com/geoff.johnson2/IR/

 

Yes indeed. My digital camera responds to infrared light. It appears on the LCD as a blue color. This happens when I flash the remote towards the lens.