CAIE IGCSE物理笔记分享：红移和宇宙大爆炸

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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