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Evidence from Galactic Red-ShiftGalactic redshift provides evidence for the Big Bang Theory and the expansion of the universeThe diagram below shows thelightcoming to us from aclose object, such as the Sun, and the light coming to the Earth from adistant galaxy
今日笔记分享：Galactic Red-Shift和Big Bang Theory
CAIE IGCSE Physics（0625）2023-2025新大纲增加了天体物理，今天为大家分享有关红移（Galactic Red-Shift）和宇宙大爆炸理论（Big Bang Theory）的笔记。
Evidence from Galactic Red-Shift
Galactic redshift provides evidence for the Big Bang Theory and the expansion of the universe
The diagram below shows thelightcoming to us from aclose object, such as the Sun, and the light coming to the Earth from adistant galaxy
Comparing the light spectrum produced from the Sun and a distant galaxy
Red-shift provides evidence that the Universe is expanding because:
Red-shift is observed when the spectral lines from the distant galaxy move closer to theredend of the spectrum
This is because light waves arestretchedby the expansion of the universe so the wavelength increases (or frequency decreases)
This indicates that the galaxies are movingawayfrom us
Light spectrums produced fromdistantgalaxies are red-shiftedmorethannearbygalaxies
This shows that thegreaterthedistanceto the galaxy, thegreatertheredshift
This means that thefurther awaya galaxy is, thefasterit is moving away from the Earth
These observations imply that the universe isexpandingand thereforesupportthe Big Bang Theory
Tracing the expansion of the universe back to the beginning of time leads to the idea the universe began with a “big bang”
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