have you ever wonder "what makes a second...a second?", wayyyy off topic Options

[lubu]

I was driving home one day in my belove celica....a question popped up in my head "what makes a second, a second"??...i know there are atomic clocks that miss a second in like 1 million year but how did we even measure a second in the first place...?

Now, a day consists of 24 hours and 1hr=3600 seconds. But we could have had 12 hours in a day and keep the same duration of a second so the number of seconds would still be 3600..it just takes twice as long to move a second to a second...so how and what instument were used to measure a second??

Imagine a second's duration were 10 times faster than today than one would says "yez..my celica can do 0-60mph in abt 60 seconds.." LOL ...yep thats a minute.

[Culpable04]

1 second can be calculated by the total movement of the earth. 1 full 360* rotation is 1 day ( 24 hrs ) hrs are made by minutes and minutes by seconds.

the movement of the earth is constant and that's the guide we have to check our timing, so a second is just a small movement of earth I have on my notes somewhere what's the distance ( or degree ) earth turn on each second. if you really wanna know about it let me know and I'll post the full formula and such. be ready for calculus and some great geometry

[BloodyStupidDave...]

1 second can be calculated by the total movement of the earth. 1 full 360* rotation is 1 day ( 24 hrs ) hrs are made by minutes and minutes by seconds.

Of course, historically you are correct (this is known as the ephemeris second - ephemeris meaning that which can be calculated using celestial or astronomic data). However, lubu is on the right track with atomic clocks. We (the human race, the scientific community) have changed our definition of a second a few times over the years. The last time was in 1997.

A second is currently defined as:

The duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom. This definition refers to a caesium atom at rest at a temperature of 0 K (absolute zero). The ground state is defined at zero magnetic field. The second thus defined is equivalent to the ephemeris second.

http://en.wikipedia.org/wiki/Atomic_clock
http://en.wikipedia.org/wiki/Ephemeris
http://en.wikipedia.org/wiki/Second