Special And General Relativity

[+EraSeek]

No real question here, just passing on things I have been reading. If you know about this topic please add to it.

 

Can you imagine the complexities involved in the GPS system? General relativity states that clocks tick slower the nearer a gravity source it is. Clocks on Earth are slower than one in space. One on a mountain top is faster than one in the valley.

 

Yet Special relativity states that faster on moving bodies the clock will tick slower than on slower moving bodies. One traveling in space tick slower than one on Earth.

 

Thus the atomic clocks on a GPS satellite traveling at speed will tick slower than one sationary on Earth, BUT, atomic clocks on a GPS satelllite in weightless space will tick faster than than one in the gravity well of Earth. These 2 factors do not cancel each other out, but obviously they do to some extent.

 

Yet there are other factors! The Earth spins! This plays a part in relativity as well. Eliptical orbits cause havoc in figuring out the relationship of relativity. Tidal potentials of the moon and sun, which are not always a consistant distance away. What elevation are you at with your GPS?

 

There is a lot that goes into this! Nanoseconds are important! Nanoseconds mean being off of your correct position by meters. Of course correction are figured out and made. They use the Earth's geoid at mean sea level as the position to correct these relativistic errors to. The corrections are in the order of about 2.4 meters, but I'm sure it must be ever changing.

 

But can you imagine what a mind bending thing to figure out all of this ! And it is only a small fraction of what goes into the GPS system.

Edited August 30, 2004 by EraSeek

[+tirediron]

No real question here, just passing on things I have been reading. If you know about this topic please add to it.

 

Can you imagine the complexities involved in the GPS system? General relativity states that clocks tick slower the nearer a gravity source it is. Clocks on Earth are slower than one in space. One on a mountain top is faster than one in the valley.

 

Yet Special relativity states that faster on moving bodies the clock will tick slower than on slower moving bodies. One traveling in space tick slower than one on Earth.

 

Thus the atomic clocks on a GPS satellite traveling at speed will tick slower than one sationary on Earth, BUT, atomic clocks on a GPS satelllite in weightless space will tick faster than than one in the gravity well of Earth. These 2 factors do not cancel each other out, but obviously they do to some extent.

 

Yet there are other factors! The Earth spins! This plays a part in relativity as well. Eliptical orbits cause havoc in figuring out the relationship of relativity. Tidal potentials of the moon and sun, which are not always a consistant distance away. What elevation are you at with your GPS?

 

There is a lot that goes into this! Nanoseconds are important! Nanoseconds mean being off of your correct position by meters. Of course correction are figured out and made. They use the Earth's geoid at mean sea level as the position to correct these relativistic errors to. The corrections are in the order of about 2.4 meters, but I'm sure it must be ever changing.

 

But can you imagine what a mind bending thing to figure out all of this ! And it is only a small fraction of what goes into the GPS system.

May I have a Tylenol?

[+sbur6]

It took you this long to figure all of that out? We all know that so we didnt see the purpose in posting it. It would just confuse the "simple" minded.

 

ScottB

[Neo_Geo]

That's why the GPS rocket scientists do what they do, and you do what you do, and I do what I do.

 

I think about all the complexities involved with that, and think "That's just too much!"

 

But then if one of their PCs goes kablooie and won't boot up, they'll just scratch their heads, think "That's just too much," and call tech support. That's when I'd go to work!

 

The only thing is that THEY probably make a lot more money than I do!

Edited August 30, 2004 by Neo_Geo

[+EraSeek]

Tell ya the truth, I'd much rather deal with this stuff than with a fussy computer! As a matter of fact, we are often discussing why we Geocache. It is the stuff like this, the miracle of what's behind the magic box that truely keeps me involved. Finding the ammo box is an excuse and a trigger to think deeper thoughts.