Wayward Satellites Test Einstein’s Theory of General Relativity

Science stories that don't cite their sources are shabby.

Here are some links. The Phys. Rev. Lett. articles are paywalled, so I've also linked to the arXiv.

"Test of the Gravitational Redshift with Galileo Satellites in an Eccentric Orbit", by Sven Herrmann et al., https://doi.org/10.1103/PhysRevLett.121.231102 https://arxiv.org/abs/1812.09161

"Gravitational Redshift Test Using Eccentric Galileo Satellites", by P. Delva et al., https://doi.org/10.1103/PhysRevLett.121.231101 https://arxiv.org/abs/1812.03711

Veritasium video on it: https://youtu.be/aKwJayXTZUs

I've been reading "The Dancing Wu Li Masters", starting the book with the full knowledge that it's form the early 70s and likely out of date. But it turns out it's not as out of date as I thought. As a total outsider to the scientific community, I would expect that what happened to Newton's laws would have happened to these earlier discoveries in the realm of quantum mechanics. But a lot of them still ring "true" today. Similarly with Einstein's general theory of relativity, as the article states, it it still holds strong. Fascinating stuff.

It's great to know that even failed technological attempts, can still result in scientific discovery (even if in this case, the discovery was that Einstein is still correct).

If I made a ticking clock out of wood but at the heart of it one gear was made out of metal and put it across the room from a large magnetic source which I could slowly increase the magnetism on.. would that be an apt metaphor for time dilation..?

Is the slowing down of time just simply the fact that all matter has some sort of core weight that has more/less friction when under the pressure of gravity?

In June, 2003 Italian astrophysicists used radio signals from the Cassini satellite to test general relativity when the sun was between Earth and Cassini -

(paywall, but nice summary in the non-paywalled abstract) https://www.nature.com/articles/nature01997

https://www-n.oca.eu/Mignard/Grex/Presentations_pdf/Grex04_B...

https://physicsworld.com/a/general-relativity-passes-cassini...