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,…… Continue reading The distance duality relation

Thesis off-cuts: the ancient history of general relativity

Chocolate frosted donuts with sprinkles are ready to be served during the grand opening of Dunkin' Donuts in Fremont, California, on Wednesday, Sept. 27, 2017. This is the first Dunkin' Donuts shop to open in Alameda County. (Gary Reyes/ Bay Area News Group)

I have recently been thinking a lot about what introductory and background material I want to include in my PhD thesis, as my self-imposed December deadline continues to hurtle towards me at an alarming speed. Concurrent with this thinking, I’ve also recently been enjoying a fantastic book called The Poincaré Conjecture by Donal O’Shea, all…… Continue reading Thesis off-cuts: the ancient history of general relativity