Is the gravitational constant, G, really a constant? Or does it change with time, or with space, or with scale in the Universe?! And if it did, could this help solve the crisis in cosmology?! Or even be an explanation for dark energy and the accelerated expansion of the universe?

A big thanks to Dr Harry Desmond, my colleague at Oxford who is an expert on modified gravity theories, for very helpful discussion while I prepared this video. https://www.physics.ox.ac.uk/our-peop…

Anderson et al. (2015; claim of periodic variation in G) –
Schlamminger et al. (2015; debunking periodic variation in G) –
Mould & Uddin (2014; measuring change in G with supernovae) –
REVIEW PAPER on measuring change in G astrophysically, see Section 4, Uzan (2010) – https://arxiv.org/abs/1009.5514
Hanımeli et al. (2022; G changing with time explaining dark energy) -https://arxiv.org/pdf/2201.04629.pdf
Desmond et al. (2022; first measurement of G outside solar system in LMC) – https://arxiv.org/pdf/2012.05028.pdf
Simpson et al. (2015; G_matter and G_light measurement) – https://arxiv.org/pdf/1212.3339.pdf
Joudaki et al. (2021; Jordan-Brans-Dicke test to find G_matter) – https://arxiv.org/abs/2010.15278

More information on the Euclid mission: https://sci.esa.int/web/euclid

00:00 – Introduction to G
01:15 – Measuring G on Earth, a brief history
02:39 – The 3 questions you can ask
04:02 – Does G vary with time?
07:04 – Can G changing with time explain dark energy effects?
08:56 – Does G vary with position in space? Measuring G in the LMC
11:11 – Does G vary with scale?
13:30 – A recap on the crisis in cosmology
14:17 – Jordan-Brans-Dicke theory, scalar fields and no-slip gravity
16:10 – Does a variable G solve the crisis in cosmology?
17:35 – The Euclid mission could help
19:01 – Bloopers

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