dr-becky 5 months ago
astrophysicist #Space and Time

Is the Strength of Gravity really Constant?

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. 

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

Dr Becky Smethurst
your friendly neighbourhood astrophysicist