Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: The Scientist on 19/07/2010 12:43:40
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We know that the speed of light is 299,792,458 metres per second. But are there any ways of controlling the speed of light? Please share your views with us. Thanks!
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that's the speed in a vacuum. you can 'control' it by sending it through another medium; the ratio of speed in a vacuum to the speed in a medium is called the refractive index. the refractive index of glass is about 1.5 - so every time you shine a light through glass you are making it drop to around 200,000,000 m/s. some materials lower the speed of light to practically pedestrian speeds - upon checking wikipedia it seems that a bose-enstein condensate of rubidium can halt light in the correct circumstances!
Matthew
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I say this with tongue in cheek but is it not slowed down by strong gravitational fields such as exist close to Neutron stars and black holes
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As far as I understand, light is not slowed by strong gravitational fields, but because of the gravitational curvature of space there may be 'more' space for it to travel through in the vicinity of a gravity well.
When viewed by a distant observer, in flatter space and who is measuring the speed by the rate of angular displacement, it might appear to slow down as it approaches the gravity well.
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Yes I realise what is the reason when I stop to think before typing.
The light moves at its normal speed but takes a longer path dipping into the gravitational well.