Einstein is right yet again

[John Clark]

The "MICROSCOPE" experiment was devised to test Einstein's equivalence principle with 100 times greater precision than had ever been achieved before, the idea that all objects fall in a gravitational field at exactly the same speed. MICROSCOPE consisted of a 402 gram platinum cylinder inside a 300 gram titanium outer cylinder that was in orbit for 2 1/2 years. Any deviations from the equivalence principle would cause the two cylinders to move relative to each other, but no such movement was detected, so any violation of the equivalency principle must be less than one part in a thousand trillion or 10^15. An even more precise satellite, MICROSCOPE-2, is planned to be launched by 2030 and it will test it to one part in 10^18.

MICROSCOPE Mission: Final Results of the Test of the Equivalence Principle

John K Clark

[Lawrence Crowell]

Well yawn, what else would we expect? I do though wonder how they account for the differential gravitational acceleration due to tidal interaction and Weyl curvature.

LC

[Stuart LaForge]

Also, I wonder why Einstein gets so much credit for the equivalence principle when both Galileo and Newton both discovered this same property of gravitation. You known, "shoulders of giants" and all.

Stuart LaForge

[John Clark]

On Wed, Sep 14, 2022 at 10:09 PM Stuart LaForge <stuart....@gmail.com> wrote:

>  I wonder why Einstein gets so much credit for the equivalence principle when both Galileo and Newton both discovered this same property of gravitation. You known, "shoulders of giants" and all.

Galileo and Newton correctly thought you couldn't tell if you were moving or standing still if you were in a closed cabin on a ship sailing on a glass smooth sea, but Einstein could  explain why you COULD tell the difference if you were sailing in a storm that had huge waves because Einstein realized that the equivalence principle only applies in flat Minkowsky space-time or if the observer is the size of a geometrical point, that is to say had no size at all. Neither Galileo nor Newton ever conceived of curved space-time, or  flat space-time, or space-time of any sort. Einstein not only knew that in a gravitational field space-time must be curved he could describe how it was curved with enough details that you could get numbers out of it and check the results experimentally. Einstein also realized the speed of causality must be finite (the speed of light) and thus the rate at which 2 clocks keep time must change depending on their relative velocity.  

Of course there are similarities between Galileo and Newton's version of relativity and Einstein's. In 1783 John Michell even predicted black holes, although he called them "dark stars''; he used Galilean relativity to deduce that if a star got massive enough its escape velocity would be greater than the speed of light and thus would go dark; however it had very different properties from a modern Black Hole. If I was far from one of Michell's Newtonian dark stars I could not see it but, unlike a real Black Hole, I could obtain a picture of it and print it in the newspaper, I'd just have to get closer in a powerful spaceship. I could even land on the classical dark star, get a sample of it and then return it to Earth, that sort of thing would be impossible with a real Einsteinian Black Hole.

 

On Wednesday, September 14, 2022 at 3:40:56 PM UTC-7 goldenfield...@gmail.com wrote:

> Well yawn, what else would we expect?

I don't think anybody was surprised by the results but the equivalence principle is so important it's good to check, after all physics experiments have produced results before that showed that something that many thought was so obviously true that it didn't even need checking was wrong. I'm thinking of the Michelson–Morley experiment. Things like that don't happen often but when they do it changes everything.

John K Clark