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Permalink Reply by Allen Sneed on January 15, 2011 at 12:44pm

Non human animal eyes can see it to. Ever seen a cat chase a tiny rainbow created by light passing through a window or something? Computers can detect rainbows too. Hence, the existence of rainbows is verified objective reality.

 

But more accurately, it is the human mind which perceives the rainbow, not the eye. The eye simply detects the light. Our minds interpret it. Our interpretation of the data that our eyes send to our minds is our subjective reality. But it is not separate from objective reality. It's all the same reality. Different interpretations.

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Permalink Reply by Richard W. Symonds on January 15, 2011 at 1:00pm

This is really interesting Allen - not just in these discussions about what is 'real'

 

I think cats - and our dog Lucy especially - don't see the colours themselves - just the changes in shades of white light - but I don't really know. 

 

A Rainbow is not just a product of the human mind's eye. If it was, a camera couldn't pick it up on a photograph. But it does, so the rainbow is objectively 'real' - but we can't touch it, feel it, hear it, smell it or taste it -only see it.

 

By the way Allen, is the rainbow (its circle) an image of the circular sun, the raindrop, or the eye - or all of these or none of these ?

 

Serious question - I have never found a satisfactory answer for 57 years !

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Permalink Reply by Allen Sneed on January 15, 2011 at 1:23pm

The scientific explanation:

 

 

 

The theist explanation: because God made it that way.

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Permalink Reply by Richard W. Symonds on January 15, 2011 at 3:29pm

Thanks guys - appreciated - but all this still does not answer my question :

 

Is the rainbow circle (or half-circle) an image of the circular sun, the circular raindrop, the circular eye, a combination, or none of these?

 

I understand it's a matter of 42-degree angles, refraction, and geometry, but that still does not answer my question.

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Permalink Reply by Richard W. Symonds on January 15, 2011 at 4:17pm

That still doesn't answer my question Neil.

 

You tell me : is the circle an image of the sun, the raindrop, the eye, a combination of these, or none of these ?

 

Simple question - simple answer please.

Permalink Reply by Allen Sneed on January 15, 2011 at 6:31pm

I don't understand what you don't get about it. The circular shape of a rainbow isn't due to the circular shape of the Sun, the water or the eye. It is a product of the angle of refraction (bent light) and geometry.  The rainbow is circular because when a raindrop bends light, the light exits the raindrop at an angle 40 to 42 degrees away from the angle it entered the raindrop. The violets and blues bend at a 40-degree angle, and the oranges and reds bend at a 42-degree angle. As a result, the only beams of light you see are from raindrops that are 40 to 42 degrees away from the shadow of your head (where your eyes are). This gives the rainbow its curved appearance. The rest of the light is unbent and appears as normal white light. The rainbow stands out from the unbent light because it has been refracted into separate colors. You are only able to see the light that directly enters your eye. The bent and separate colors of the light that enter your eye do so at a specific angle from the sky. The rest of the bent light waves "miss" your eyes and therefore are invisible to you. But the bent light waves that "hit" your eyes are coming from a specific angle due to the refractive properties of water droplets in the air. This 40-42 degree angle, when applied across your field of vision, creates a circular shape - like when you use a compass to draw a circle from a fixed point. In the case of rainbows, your eyes are the fixed point.

Permalink Reply by Richard W. Symonds on January 15, 2011 at 7:47pm

Thanks Allen - that's a really good explanation. It's not an image of the sun, eye or water. It's to do with angles & geometry.

 

Could you possibly amplify on what you mean by the "shadow" ?

 

I know that if you draw a straight line from the sun (a ray of light), through the perceiver's eye and out, that line will end at the (unperceived) centre of the rainbow. I also know that no-one sees the same rainbow - it is unique to that perceiver.

 

Maybe you can answer a related question Allen?

 

If I walk along Brighton promenade on a sunny day, the sun's rays reflect on the water straight to my eyes - and follows me as I walk.

 

If my wife is 100 yards further on, exactly the same is happening with her.

 

Why can't we see each others's rays of sunlight across the water? 

Permalink Reply by Allen Sneed on January 15, 2011 at 8:48pm

The shadow of your head on the ground has to do with the angle of the sunlight coming from the sun. This angle of the light from the sun will determine the apparent height of the rainbow that you see proportional to the height of your shadow. In a sense, a rainbow is like a shadow in that it depends on the angle of the light from the Sun and the physical objects that either block or bend the light before it reaches our eyes.

 

The glare from Sun's light on the water at the Brighton Promenade seems to follow you for the same reason that a rainbow seems to always be the same distance from you as you walk toward it. What you are seeing is refracted light against the backdrop of non-refracted light. The point of contrast between the refracted and non-refracted light is at a specific angle to your eye. That angle remains the same as you walk so the point of contrast (or the glare of light) appears to be at the same distance from you at all times.

 

Think of light as individual photon particles for a moment. Your wife occupies a different point in space so the light photons that hit her eyes are different than the light photons that hit your eyes. The ones that hit her eyes are coming from an angle from the Sun in front of her. The apparent distance of the glare will depend on your wife's height and the angle of the Sun in the sky. The light photons that enter your eyes will have been reflected off the surface of the water at a different point than the light photons that entered your wife's eyes.

 

Or, try visualizing it as if the Sun is repeatedly and rapidly shooting out continuous walls of tennis balls. The tennis balls represent photons of light in this example. You and your wife occupy the left and right side of the tennis court respectively. The balls that hit your wife are different than the balls that hit you and they will have bounced off the ground in front of your wife at a different point than the balls that hit the ground in front of you. Only balls that hit the ground at a specific angle in front of you will hit you in the face and only the balls that hit the ground at a specific angle in front of your wife will hit her in the face. And you both are getting hit in the face with different balls. The balls that miss your face could potentially hit someone else or they may simply bounce back into space. But everyone who gets hit with balls is getting hit with different balls, or different photons of light from the Sun.

 

(After re-reading this comment I can see that someone might take it out of context. I do not mean to imply any sort of malice or double meaning here. The tennis balls simply represent photon particles.)

Permalink Reply by Jaume on January 14, 2011 at 11:25am

Philosophers will tell you that materialists and idealists disagree on what's real, but don't believe them. If I've learned one thing in my life, it's that, whatever they claim, materialists and idealists alike behave as if they believe that only money is real.

Especially if they live in Brazil.

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Permalink Reply by Jaume on January 14, 2011 at 11:29am

How do they call their currency in Brazil?

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Permalink Reply by Michael Sizer-Watt on January 14, 2011 at 1:26pm

That's what Descartes wanted to know.  As much as I hate him, his "3 filters of reality" are ingenious.  (I still hate him).

 

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Permalink Reply by Richard W. Symonds on January 14, 2011 at 5:24pm

Bloody clever these French - as much as we might hate them (sorry Michel) - Descartes, Pascal, Voltaire, Foucault...

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