Astronauts to Experience Time Dilation

When astronauts head to Mars, they will experience time dilation. That's to be expected. In fact, your feet and your head experience time dilation, with your head aging ever so slightly faster than your feet. But how much time dilation will they experience (relative to Earth observers)?

First off, let's check we're all on the same page. Time passes at different rates for different observers, depending on their relative speeds, and their proximity to (and strength of) nearby gravitational fields. Time dilation is the difference between time elapsed on two clocks due to these causes, as described by special relativity and general relativity.

Gravity curves spacetime. The result is that the stronger gravity is near you, and the closer you are to the mass creating it, the slower time moves (from the standpoint of an observer, or whoever has the second clock. From your perspective, time ran at the usual speed). This is how your foot is younger than your old (relatively speaking) haggard head.  READ MORE...

Einstein Was Right

According to Einstein's relativity, if you move relative to another observer and come back to their starting point, you'll age less than whatever remains stationary. Einstein also tells us that the curvature of space itself, depending on the strength of gravitation at your location, also affects how fast or slow your clock runs.

By flying planes both with and against Earth's rotation, and returning them all to the same starting point, we tested Einstein as never before. 

Here's what we learned.

In 1905, our conception of the Universe changed forever when Einstein put forth his special theory of relativity. Prior to Einstein, scientists were able to describe every “point” in the Universe with the use of just four coordinates: three spatial positions for each of the three dimensions, plus a time to indicate which moment any particular event occurred. 

All of this changed when Einstein had the fundamental realization that every single observer in the Universe, dependent on their motion and location, each had a unique perspective on where and when every event in the Universe would have occurred.

Whenever one observer moves through the Universe relative to another, the observer-in-motion will experience time dilation: where their clocks run slower relative to the observer-at-rest. 

Based on this, Einstein suggested that we could make use of two clocks to put this to the test: one at the equator, which speeds around the Earth at approximately 1670 km/hr (1038 mph), and one at the Earth’s poles, which is at rest as the Earth rotates about its axis.  READ MORE...