How We Know the Universe is Expanding (Cosmological Redshift Explained!)
0Ever wondered how scientists know the universe is constantly growing? Dive into the fascinating world of cosmological redshift! [0:00] This video breaks down the primary evidence for an expanding universe: the observation that light from distant galaxies is shifted towards the red end of the spectrum.
We'll explain how this phenomenon, called cosmological redshift [0:11], occurs because light waves get stretched out as the universe expands, similar to how sound waves change pitch as a source moves away. Imagine standing still as a wave approaches versus moving towards it – the effect on the wave is key! [0:19, 0:27]
Crucially, we're seeing the "opposite" of moving towards a wave – the light is shifted towards red [0:46], indicating galaxies are moving away from us. This makes perfect sense when you consider the Big Bang theory, where everything is flying apart! [0:56]
Learn how astronomers use the amount of redshift to determine how fast galaxies are receding [1:06] and how data from telescopes like the Hubble Space Telescope [1:23] creates stunning maps of the universe, showing the incredible speed at which galaxies are moving away from us. [1:28]
If you're curious about the cosmos and the evidence behind the universe's expansion, this video is for you!