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the 'Stuff That's Just Really Interesting 'thread

It's about time... and anyone who depends on GPS

"As time stretches, it slows.

The best-known force that stretches time is gravity. The more gravity somebody experiences, the slower time passes for them when compared to someone in a lower gravitational field.

The effect is miniscule compared to a human lifespan, but it is real and measurable. Boulder, Colo. is a mile above sea level. That means the gravitational field is slightly weaker, and time ticks by a little faster.

But modern technology can't deal with flowy time like this. As a result, the timekeepers at Boulder and elsewhere make corrections to ensure these different flows of time look like they're ticking in lock-step. The same goes for satellites farther from Earth, like those that make up the Global Positioning System. The system works by measuring the time difference between several satellites carrying clocks in space to the time that people measure on the ground.

Without correctly calibrating for the difference of the ticking clocks inside the GPS satellites, the system wouldn't be as accurate, Prescod-Weinstein says. "Any kind of system that uses GPS requires general relativity," she says. "You have to understand what time flow of the satellite is like and how that is different from time flow from Earth."

Atomic Clocks and Time NPR
 
I always knew you could get seriously hurt on a Slip & Slide but didn't know it was pulled at one point.

Legal Eagle is one of my favorite channels on Youtube. It'd be nice if there was as polished a Canadian equivalent too. It's badly needed given the number of Canadians that talk about their 'First Amendment' or 'Second Amendment' rights and don't seem to understand that the Canadian constitution and Canadian law are not the same as the American's....
 
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