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why couldn't atoms form in the early big bang?

In an atom, the electrons are held around the nucleus by electromagnetic forces. The electrons have a negative charge, and the nucleus has a positive charge, and these attract. But if you give the ...
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4 votes

Why is the H-alpha line slightly shorter in wavelength (656.28 nm) in air than in vacuum (656.46 nm)? Shouldn't it be longer?

This is not due to where the light is emitted, but where it is measured. When light enters a medium, such as air, it slows down. This is called refraction (and is the reason that prisms etc can bend ...
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