Gravity Probe B confirms Einstein effects

[DREDIOCK]

Pretty interesting read

The satellite's observations show the massive body of the Earth is very subtly warping space and time, and even pulling them around with it

http://www.bbc.co.uk/news/science-environment-13286241

[Meatwad]

That explains the mystery of Deja vu

[curry1]

Pretty interesting read

The satellite's observations show the massive body of the Earth is very subtly warping space and time, and even pulling them around with it

http://www.bbc.co.uk/news/science-environment-13286241

I didn't read the article but I don't understand how this is a major discovery or anything new worthy?  We have been having to reset the clocks on satellites for many years now.  We already proved that this happens.

[Karnak]

I didn't read the article but I don't understand how this is a major discovery or anything new worthy?  We have been having to reset the clocks on satellites for many years now.  We already proved that this happens.

No, that is a different one of Einstein's theories.

[BoilerDown]

Time dilation is a well tested result from special relativity, this is probably about frame dragging which is a prediction based on general relativity that hasn't been so well tested.

[PJ_Godzilla]

Time dilation is a well tested result from special relativity, this is probably about frame dragging which is a prediction based on general relativity that hasn't been so well tested.

Right. I didn't realize, however, that satellites are moving at a significant enough speed relative to earth frame that this was necessary. If I recall, it was the Lorentz transforms (almost sadi Helmholtz, haha) we'd use to adjust from one frame to another.

it goes like t'=gam*(t-v*x/c^2) and gam=1/(sqrt(1-v^2/c^2)  where v is the velocity of the prime frame relative to the other. You can see that gam gets pretty small if v isn't a significant fraction of c - as does v*x/c^2.

I guess I'm recalibrating my idea of the relative-to-earth speed of those satellites.

[Mano]

interesting read. Thanks for the post.

 

[BoilerDown]

Right. I didn't realize, however, that satellites are moving at a significant enough speed relative to earth frame that this was necessary.

It obviously isn't necessary, because if it was, they wouldn't have needed to set up the experiment, and they would already have the data and the mechanics would be widely known and accounted for by everyone sending anything into orbit.

I guess I'm recalibrating my idea of the relative-to-earth speed of those satellites.

Yeah... no.  You don't need to.

[PJ_Godzilla]

It obviously isn't necessary, because if it was, they wouldn't have needed to set up the experiment, and they would already have the data and the mechanics would be widely known and accounted for by everyone sending anything into orbit.

Yeah... no.  You don't need to.

If my intuition was correct and they are NOT moving at a significant enough fraction of c relative to earth to require recal, then the poster to whom I was responding was incorrect...

Remind me to rip that guy.