GK
BIG BANG THEORY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Why do red-shifted light spectrums from neighboring galaxies indicate the universe is expanding?
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Red light has the shortest wavelength on the visible light spectrum
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Red light has the longest wavelength on the visible light spectrum
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Red light has both long and short wavelengths on the visible light spectrum
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Red light has neither long, not short wavelengths on the visible light spectrum
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Explanation:
Detailed explanation-1: -Ever since 1929, when Edwin Hubble discovered that the Universe is expanding, we have known that most other galaxies are moving away from us. Light from these galaxies is shifted to longer (and this means redder) wavelengths-in other words, it is ‘red-shifted’.
Detailed explanation-2: -This type of redshift is called the cosmological redshift. And here’s the relation between distance and redshift: the further away a galaxy is, the longer its light takes to reach us. A longer light travel time means more cosmic expansion, more wavelength stretching and thus a higher redshift.
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