Less than a month till Christmas, and I'm not really sure where 2009 has gone. Like a supersonic man, it's been travelling at the speed of light. In fact, I'm convinced that time is speeding up and that we're entering some kind of universal endgame. But that's for another blog, so instead for this blog instalment I've tried to enhance my scientific understanding of these things with a look at radiation and light in particular. I've got my end of module Chemistry exam this wednesday for my course at Birkbeck, so I'm hoping to let my mind wander to happier things outside the sphere of science next month, but for the time being this is all I have to offer, dear blog ...
Radiation gets a bad press and stirs up dark thoughts in the public psyche, but put simply it's just the emission of energy (heat, light, etc) from a physical body. It wasn't until the 20th century that scientists fully understood light, for example, and its dual wave-particle nature. For many years, Newton's idea of light particles or "corpuscles" held sway, until Thomas Young performed a number of experiments in the early 1800s showing the diffraction and refraction of light and its wavelike behaviour. The scientific community was divided until quantum theory solved the dilemma, thanks in particular to advances by Einstein who synthesised the two ideas and showed how light can exist both as a wave and as discrete light packets (photons) that behave like particles, a discovery that earned him the Nobel Prize in 1921.
Light is electromagnetic radiation, and what humans can see with the naked eye is just a small slice of the electromagnetic spectrum, the ROYGBIV (red orange yellow green blue indigo violet, or Richard of York gave battle in vain) of the rainbow that every pupil memorises at school. However, most light has a wave frequency that makes it invisible, from radio waves and gamma rays at one end of the spectrum to UV rays, X-rays and gamma rays at the other end. Einstein also saw that light was the only constant in the universe, and this discovery led to his special theory of relativity, e = mc2, where both time and space are elastic and bend relative to the observer to allow for the constant speed of light (c).
Two key British scientists crucial to the development of this theory in the 19th century were Faraday, whose experimental work with coils showed that alternating an electric current can create a magnetic field, and Maxwell, who made sense of Faraday's experiments mathematically by formulating equations that point to the eloquent relationship between electricity and magnetism. From studying these equations, Einstein recognised a constant that kept appearing in each experimental result and this he later discovered to be the speed of light. By cracking this secret of the universe, a whole series of technological advances were unleashed in the 20th century, including TV, radio, atomic bombs and the blogosphere.
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