• Question: i know this isn't your topic of research, but are things actually in colour or is it how we see them in our eyes?

    Asked by to Andrew, Elaine, Emma, Michael, Nancy on 17 Jun 2014. This question was also asked by .
    • Photo: Nancy Carlisle

      Nancy Carlisle answered on 17 Jun 2014:

      Such a good question! It’s very intersting. Our experience of color depends both on the signals received in our eyes (light bounces off the various objects and then gets sent to our eyes, our eyes convert it into a neural signal) and our brain. Other animals have different types of receptors in their eyes, and so the wouldn’t see the world in the same way we do. For instance, bees can see ultraviolet light that we can’t see- and actually a lot of flowers reflect ultraviolet light to attract bees. Little did we know there is a whole world of color around us that we aren’t aware of! 😉

    • Photo: Michael Kelly

      Michael Kelly answered on 17 Jun 2014:

      Light is part of a larger body of radiation from x rays to radio and micro waves, called the electromagnetic spectrum. But because we have cells in our eyes that convert this radiation to an electrical signal we can become aware of it.
      The sensation of colour arises from the interaction of your eyes with the radiation reflected from objects in your environment. Other species have receptors that convert ultra violet light bees, and to a lesser extent chicken. Also birds have a greater variety of colour receptor so they probably experince a greater range of colours.

    • Photo: Andrew French

      Andrew French answered on 17 Jun 2014:

      This is indeed a great question! 🙂

      I think there’s two parts to the answer: the physics of light, and the idea of how we perceive it (see it)

      The “colour” of an object is the colour (particular set of wavelengths) of light that is reflected back off it. This depends on the colour of light illuminating it, and the physical properties of the object (whether it absorbs or reflects particular wavelengths). So an object that reflects all wavelengths equally will appear white, if lit with white light, but will appear red if lit by red light (it can’t reflect blue light if none hits it in the first place!).
      If it absorbs all light it will appear black. If it absorbs just bits of the spectrum, the colours it absorbs will appear dark, and the ones it reflects will appear bright. This is why you can illuminate e.g. a plant with white light, and the plant will appear green (it absorbs more red and blue, and reflects more green)

      The above is true even if there is no person or animal around to observe it. It will still reflect the wavelengths of light, they just won’t enter anyone’s eyes.

      The second part of the problem is how we perceive the light. As Nancy and Michael already mentioned, different species can detect (see) different colours of light. So an object that reflects only the ultraviolet part of sunlight (if such an object existed) would appear ultraviolet to bees (assuming they could tell the difference between UV light and other wavelengths – I’m not sure! – otherwise it would just appear ‘bright’), and the same object would appear black to us.

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