Thesis off-cuts: how special is our place in the Universe?

Thanks to many hundreds of people making dedicated observations of the sky over many decades, we know that the majority of our Universe is comprised of two substances: dark matter and dark energy. Dark matter is an unknown type of matter, referred to as "dark" because it does not interact electromagnetically, meaning that it doesn't …

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The distance duality relation

The distance duality relation tells us how, assuming that photons propagate on null geodesics in a pseudo-Riemannian spacetime and that their number is conserved, luminosity and angular diameter distances are related, via where dL is the luminosity distance, dA the angular diameter distance and z the redshift. This relation was introduced by Etherington in 1933, …

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