Time Doesn't Flow at the Same Rate Everywhere

Time Doesn't Flow at the Same Rate Everywhere When you look at a clock, you probably think you are looking at time. But what you actually see is a number. A measurement produced by a physical process. And the strange part is that this measurement does not behave exactly the same under every condition. Change the speed, and the measured rate of time changes. Change the gravitational field, and it changes again. This is not just a theoretical idea. GPS satellites carry atomic clocks that run at a different rate from clocks on Earth, and those differences have to be corrected for GPS to work accurately. From there, the question becomes much bigger. How do we actually define a second? Why did Newton believe time was universal, and why did Einstein show that it could not be? Why does time seem to move in only one direction? Is there really one shared “now” for the entire universe? And could what we experience as time be different from the time described by physics? We can measure time with extraordinary precision. But measuring something precisely does not necessarily tell us what that thing actually is. Perhaps the strangest question is the simplest one: What exactly are we measuring when we measure time?