The Copernican principle states that the Earth is not in a special place in the Universe. Us humans are not privileged observers, we’re seeing the same Universe as everyone else; and the observations we make from Earth are representative observations taken from an average, random position in the Universe. It’s named after Copernicus, the mathematician who put the Sun, and not the Earth in the centre of his mathematical model of the Solar System, who was the first to “demote” Earth from a special place in the Universe. It says there is nothing unique about Earth’s position in space, and that the laws of physics are the same here as anywhere else in the Universe. It is the main philosophical and physical assumption that underlies all of cosmology – the branch of astrophysics which deals with the properties and evolution of the entire Universe – so every model and theory we have about the Universe (from the Big Bang to LambdaCDM) all of them have the Copernican Principle at their foundation. And yet, the Copernican Principle has never been fully proven, because it can’t – it’s a philosophical assumption at heart rather than a fully fledged scientific theory. But we can gather observations of the Universe that help support this massive assumption…

Hubble (1929) – https://www.pnas.org/doi/full/10.1073…
Hubble (1929) – https://articles.adsabs.harvard.edu/p…
Riess et al. (1998) – https://arxiv.org/pdf/astro-ph/9805201
Fosalba et al. (2003) – https://arxiv.org/pdf/astro-ph/0307249
Scranton et al. (2003) – https://arxiv.org/pdf/astro-ph/0307335
Uzan, Clarkson & Ellis (2008) – https://arxiv.org/pdf/0801.0068
Caldwell & Stebbins (2008) – https://arxiv.org/pdf/0711.3459
Clifton, Ferreira & Land (2008) – https://arxiv.org/pdf/0807.1443
Tomita & Inoue (2009) – https://arxiv.org/pdf/0903.1541
Keenan, Barger & Cowie (2013) – https://arxiv.org/pdf/1304.2884
Kreisch et al. (2022) – https://arxiv.org/pdf/2107.02304

00:00 Introduction
03:48 Why we can’t prove the Copernican Principle
04:58 Evidence in support of the Copernican Principle
09:59 Evidence against the Copernican Principle
13:33 Bloopers

Video filmed on a Sony ⍺7 IV
Video edited by Martino Gasparrini: https://www.fiverr.com/mgs_editing

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