Back to the Present

Hello, scientists!

Today we are going to try to tackle another physics question. Let me warn you, however, that I'm wearing a band-aid, so there may be some typos. Let's begin!

Today's topic sounds philisophical, and it kind of is. The fact is that there is no definite past, present, or future. At first, you may argue that the year 1980 was in the past, 2014 is in the present, and 2030 is in the future. I would agree with you, but only because our time frames are almost identical. This means that one second to me is (pretty much) one second to you, and we move through time at the same rate.

If you went to work on the International Space Station, things may start to get strange for two reasons. One, satellites move at incredible speeds, often faster than we give them credit for. In fact, the fastest satellite speed is about 17,650 miles per hour. As the theory of relativity tells us, the faster an object is moving, the slower it moves through time. However, this doesn't affect the time dilation as much as another factor: gravity. It has been proven that a thing that is being affected by a gravitational pull moves through time more slowly than an object that is not being affected by gravity at all.

Because of the effect gravity has on satellites, they move through time more quickly than us because they experience less gravity, due to their height. To fix this, scientists have programmed clocks on satellites to run a little slower than they should, so they wouldn't fall out of sync with the ones on the surface. Otherwise, the loss wouldn't be tremendous (only 1.7 seconds per century), but it still would cause problems with any GPS system.

This also, amazingly, means that past, present, and future are just relative. If I took a light-speed trip around the universe, my future would be your past. On the other hand, I could just spend thousands of years in a satellite, but where's the fun in that?

This is a short entry, but this thing isn't a difficult concept to explain. Anyway, comment about stuff I got wrong or missed or suggestions for next time. I'll probably cover something about astronomy tomorrow, so make sure to check it out!

Until next time,
Ben's jamin'
Benjamin

P.S. Make sure you check out John's math blog at http://johncooksmathblog.blogspot.com.