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How do 3D glasses work?
Thursday, August 12th, 2010
Normal 3 D vision works because our left eye has a slightly different view of the world from our right eye.
3 D glasses typically have the left-hand optic covered in red and the right hand-optic covered in blue. The 3-D material – a picture or a single frame of a film – has two images printed, one in red and one in blue. When we view this image through the glasses our left eye mainly sees the image printed in red and our right eye mainly sees the image printed in blue. Our brain interprets the differences between the different images as being due to differences n perspective and reconstructs a 3-D view of the scene. (more…)
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Why are plants green?
Friday, July 2nd, 2010
I guess there are two parts to the answer- why is green a good colour for plants to be, and how do they go about it. The key to the first part lies in how plants go about the business of living- they use light energy from the sun to drive the process of photosynthesis, which converts carbon dioxide into the sugars that they need to survive.
The fact that the leaves are green is because they are reflecting green light, and absorbing the other colours in the visible spectrum. When the light is absorbed, it is absorbed by the atoms that make up the leaves. These atoms, stuck together in molecules, gain energy from the light and this is needed to run photosynthesis. The reason plants decide to use visible light as opposed to infra-red or ultra-violet light is the same reason as why we see in the visible- there’s plenty of it around to use!
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What is beyond the edge of the universe?
Tuesday, June 15th, 2010
Firstly – and obviously – nobody knows. But you have actually asked two questions.
Firstly there is the observable universe, and then there is the Universe, and then there is your question. As we understand it at the moment, the story goes like this:
Initially the universe was filled with ‘primordial substance’ (protons, neutrons, and electrons mainly but not assembled into atoms) and was opaque to light and radio waves. About 300,000 years after the big bang, the universe condensed from separate protons and neutrons and electrons into atoms and at this point the universe became transparent.
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