The Week in Science

Have you ever wondered why time seems to go by much faster when you are sleeping, or when you are hurrying to finish that midterm assignment? Well unfortunately time dilation can’t be to blame, unless of course you happen to be trying these while in orbit.

Much like with Blackholes, there are different types of time dilation. Today I will be focusing on the simpler of the two, known as “gravitational time dilation.”

The first and most important thing to understand about time dilation, and time in general, is that our experience of it is completely relative. To us we will always feel that time is passing normally, especially when observing a point of view where time is moving at a different relative speed.

In the simplest terms, the effects of both velocity and gravity affect time, changing the way we move through it, but not how we experience it. This means that the higher the gravity the slower time moves, and the faster something moves, the slower time moves with them.

You might be asking yourself how we can even know that this exists. Well, that goes back to Einstein and both his theory of general relativity and his theory of special relativity. It hasn’t been until fairly recently though that these effects could be measured and proven outside of mathematical equations.

In fact, the astronauts aboard the International Space Station (ISS) are affected by time dilation, and as such their clocks moves differently. Because the ISS is orbiting the Earth at a relatively high velocity time appears to be moving slower, and with less gravity time should be moving faster; but these effects are not equal, and as such time actually moves slower for them.

Now don’t worry, we aren’t going to be bringing back people from the ISS that have only aged a year when their grandkids are ready to retire. The overall effects are so minimal that there only seems to be a difference of one thousandth of a second every six months. So even though it’s nothing drastic, it is still a fascinating phenomenon, and is something that will need to be addressed when traveling deeper into space.