I just finished watching the first episode in the new BBC Horizon series, it was entitled “Do You See What I See“. It was interesting but at the same time disappointing. I would summarise the subject matter in general terms as What you perceive is subjective, what actually exists is objective. In this episode they talk about colour, but it can be equally applied to light/dark, pain, temperature, taste, loudness/quietness etc.
One thing I didn’t like was when Dr Beau Lotto makes statements like: colour is an illusion, colour doesn’t exist. Ok, it’s a popular science program not an academic conference, but FFS get the simple things right and be clear about them. If you want to assert that each individuals perception of colour is different – that’s fine. If you want to say that colour is a human construct of language that describes a perception – that’s fine. But be clear about what your saying. Assertions like colour doesn’t exist can only be designed as headline-seeking-soundbytes, and they do a disservice to science and otherwise respected programmes like Horizon, imho.
Electromagnetic Spectrum (Image: http://en.wikipedia.org/wiki/File:EM_spectrum.svg)
In Physics we tend to be quite specific when we talk about colour, i.e. we talk about the wavelength of electromagnetic radiation. The electromagnetic spectrum includes visible light, x-rays, radio-waves, microwaves, etc. We use wavelength of EM spectrum because it is objective, observable, measurable, and reproducible; whereas colour perception is purely subjective. We use equipment to measure the wavelength and it has a number not a name. So while we can say Sodium burns with an orange glow, it’ll be backed up with a wavelength such as 589 nanometers (and include a stated margin of error depending on equipment used).
But there were interesting parts too. The effect of language on colour was fascinating, and this was brilliantly demonstrated with a piece on the Himba tribe of Northern Namibia. They classify colours in a different manner to most Westerners and have only about half the (names for) colours we use. So they say milk is white, but they also consider water as white – we’d consider it transparent (or blue according to the programme). But the most interesting part was where the Himba couldn’t easily discern between certain shades of blue/green – which would be easy for Westerners; but conversely there were shades of brown/green they could easily discern which Westerners struggle to discern. I’ve also noted that children (Western and presumably all children) will describe water as white – until they’re told it’s transparent (or blue if that’s what some people call it).
Other interesting aspects of colour included how our perception of colour is effected by the surrounding colours, by colours we’ve just been looking at, by age, gender, etc. There are countless optical illusions (google it) that brilliantly demonstrate, imho, what we see is a subjective perception; the reality in the external world is an independent objective reality.
This episode was a good start to the Horizon series, which itself is a stalwart well worth a series-record. Go Horizon!
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So I unleashed my camera, did some time-lapse astro-photography, and made a movie using those images. The big bright thing that looks like the Sun – that is actually sunlight, reflected from the Moons surface. Below and to the right of the Moon, that bright ‘star’ – that is actually sunlight, reflected from Jupiter 
Abortion
11 weeks old, I saw one like this at The Human Body Exhibition.
“In war, truth is the first casualty” – Aeschylus. And so it is in the abortion war between the bigoted partisans of the Pro-abortion Vs Anti-abortion divide. In a recent TV debate I was struck by the disinformation trotted out, non-issues and red-herrings. I don’t care if you’re for or against abortion. But people should make rational decisions based on accurate information – not disinformation and propaganda; wherever it may arise. Here I address some of the disinformation…
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