In layman's language please..... Explain the atomic clock?

Question

Am I wrong in presuming that time is measured by the spin of the earth? Hours to mins to seconds and all according to one revolution? Because if that is the case, then time is going to vary from planet to planet isn't it? So is the atomic clock based on the spin of an electron of a certain ?? (Forgot the word... have drawn a blank.... The opposite of a compound) A quartz perhaps?
If time is based on this then its obviously fundamental measure and not something created by man according to the diameter of this rock we are all sitting on.

Answer 1

The atomic clock is amazing. Here's how it works:

First, they cool cesium enough to slow the molecules, then keep it at a constant temperature.

The atoms of the cesium still vibrate, so a laser keeps track of how many times the atoms vibrate.

Since the atoms vibrate at a constant rate, when the count reaches the specified number, one minute has passed.

Time is measured by the spin of the earth, but the atomic time standard is alot quicker method of keeping track. The time from the Atomic clock was intially calibrated from all the measurements of the earth's rotation.

The quartz watch on our forearm use the same technique in keeping time, but isn't very precise because of the huge temperature changes our watches face everyday in the real world.

Answer 2

Basically you keep a bunch of Caesium atoms at constant temperature and count their oscillations. When the count reaches 9192631770 (which is a pretty huge number) then 1 second has passed. The counter is reset to zero and counting begins again. Its because the count is so large that the clock is accurate. If the count is 9192631771 then the error in the length of a second will be negligible. Quartz watches work by counting the vibrations of a quartz crystal which vibrates at (I think) about 34000 cycles per second. This still makes for a pretty accurate clock.

Answer 3

ST K, You've already got some good answers above on the science of the atomic lclock, but let me answer in a clarifying way:

Our units of time, year, day, etc, are originally DEFINED by earth's planetary cycles, but not MEASURED by them. Meaning that the length of a day is defined by one rotation of our planet, but it would be very difficult to measure where our planet is in that rotation at any given point in time. It turns out it is easier to measure the vibrations of the Cesium atoms, as the answer above explained.

What scientists did was agree on what would be the standard measurement tool, the Cesium atomic clock, then agreed on how many vibrations of the atom were equal to the average terrestrial revolution, and then RE-DEFINED a day as that many cesium vibrations.

As it turns out, the rotation of the earth is NOT consistantly exactly the same speed, but scientists need a standard and unchanging definition of time, so now it is determined by atomic clocks.

Things that need very precise timing measurements to work, like GPS devices or cellular phone networks, can now rely on the Atomic time, which is far more accurate.

Answer 4

Time is not measured strictly by the spin of the Earth. We find it convenient to place major dividing points by the spin of the Earth (days, years), but we could just as easily use any other regularly occuring event. An atomic clock uses Cesium, and the regular oscilation of its atoms, to make a very, very precise clock. It's still affected by relativity, but it's a very precise instrument.

On another planet, we could take a clock and a calendar and measure "Earth days". It would probably end up being easier to just measure a day on that planet though (if they were off even by a little, we'd end up mixing day and night up pretty badly, pretty regularly), and have separate clocks and calendars, one of them unofficial.