Sunday, November 05, 2006

Space and Time

You are never in the same place twice, and you never know exactly what time it is. Let me explain:

You are never in the same place twice when you state your position from an absolute fixed point in space. The Earth spins on its axis and revolves around the Sun, the Sun revolves around what is thought to be a super massive black hole, and the Milky Way galaxy itself is moving at around 300 km/sec. While you may be in the same place on Earth, from an imaginary, immovable point in space you are in a new location every second of the day.

You never know exactly what time it is ever. You do however get to know what time we think it was a month ago to a certain resolution. You never know exactly what time it is ever because the atomic clocks we use to keep track of the passage of a single second are not perfectly accurate. Furthermore, the exact time also depends on your altitude (gravity) and speed. With looser margins of error you only know what time it was a month ago. There are many atomic clocks and groups of atomic clocks that keep time very accurately. When all of the data from the world's clocks has been compiled and weighted the BIPM (International Bureau of Weights and Measures) releases the final numbers for the previous month.


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