How much does Earth's time dilation decrease with distance from the surface?

[403036387]

Exactly how much does Earth's time dilation decrease with distance from the surface?
I know that it's way to small to ever notice and probably even mesure with today's instruments, but I'm trying to calculate how many billionths or trillionths [or less] of a second a clock might run faster if it was only about 15 feet off the ground.

 

[pmb_phy]

Exactly how much does Earth's time dilation decrease with distance from the surface?
I know that it's way to small to ever notice and probably even mesure with today's instruments, but I'm trying to calculate how many billionths or trillionths [or less] of a second a clock might run faster if it was only about 15 feet off the ground.

Actually it was measure back in the earlu 60s if a famous experiment. It was done at Harvard University by Pound and Rebka.

Pet

 

[403036387]

really? that low? cool. you wouldn't happen to know how much it was...or where i could search to find it? I've been working out my own problems but seeing as i havn't even had high school physics yet, I'm not sure if it's anywhere near right.

I found somewhere where somebody at 1340 feet gained 22 nanoseconds.
so i did 1340:22= 15:x and x=4.6
so i put down ground time=1second and 15foottime=1second+4.6 nanoseconds.

what I'm really looking for in my end result is how long it would take you [how many LIFETIMES!] to catch up to your twin who was born two hours before you if you hovered 15 feet in the air.

so i found that there are 7.2x10^12 nanoseconds in two hours and i divided it by 4[number of nanoseconds gained per ground second] multiplyed by a billion to get seconds. divided by 60, 60, 24, and 365 to get 5,549,213,597,158 years to gain two hours.

i know that's a bit confusing...i apologize. is this completely wrong?