Atomic clock

[Primarygun]

What's a atomic clock?

I heard that there are radium in them.

And it's very precise

[YT2095]

the ones I`ve heard of use Caesium, that`s encased in a sheild with a small hole in it, to let a "beam" of radioactive decay particles out, the decay rate is SO constant that it is used in conjunction with a counter and then subdivided down into what we call seconds and minutes etc...

[Gant]

They actually can be,,but i recommend.

 

Check out this site for more info.

 

http://science.howstuffworks.com/atomic-clock1.htm

[YT2095]

Check this out: http://www.heret.de/radioclock/ptb.htm

 

esp this bit: "The unit of time, the second, of the International System of Units (UI) which is based on the oscillation of the caesium-133 atom was defined in 1967. This consistently led to an international atomic time scale related to the second at sea level and to the zero meridian. This scale superseded the "universal time" - also known as "Greenwich Mean Time" obtained from astronomic observations. The time scale used now is called "Universal Time Coordinated" (UTC). Leap seconds intercalated into the UTC time scale about once a year ensure that UTC never deviates from the Universal Time determined by die Position of the sun by more than 0,9 second."

 

that`s the sucker I was talking about

[Gant]

Hmmmm,,,thats pretty dam cool,,i bookmarked the sight to learn more. But i remember such a device,,just wasn't sure if that was exactly accurate as to its workings. Wasn't sure if the rate of decay was what was being measured.

[ed84c]

The most precise clocks in the world all though short lived are made from the decay of hydrogen isotopes.

[swansont]

the ones I`ve heard of use Caesium, that`s encased in a sheild with a small hole in it, to let a "beam" of radioactive decay particles out, the decay rate is SO constant that it is used in conjunction with a counter and then subdivided down into what we call seconds and minutes etc...

 

No, nothing radioactive involved. The second is defined in terms of the hyperfine transition of the ground state, so you have to shine microwaves on them to get them to oscillate (9 192 631 770 Hz for an unperturbed atom)

[swansont]

The most precise clocks in the world all though short lived are made from the decay of hydrogen isotopes.

 

No. You may be thinking of hydrogen masers, which use a microwave transition in the hydrogen. These are very good clocks in the short term, but they drift. The most precise clocks in the longer term are atomic fountain clocks.

[YT2095]

No, nothing radioactive involved. The second is defined in terms of the hyperfine transition of the ground state, so you have to shine microwaves on them to get them to oscillate (9 192 631 770 Hz for an unperturbed atom)

well forgive me for not going into mega detail, I WAS trying to keep it as simple as possible here!

[The Nacho]

Go to www.time.gov to find out the REAL time. I think the atomic clock only gets off something like 1 second every thousand years or sumthin'.

[swansont]

Go to www.time.gov[/url'] to find out the REAL time. I think the atomic clock only gets off something like 1 second every thousand years or sumthin'.

 

"This web site is intended as a time-of-day service only. It should not be used to measure frequency or time interval, nor should it be used to establish traceability to NIST or the USNO."

 

"REAL time" is a bit of a misnomer. It all depends on how well you can realize the definition of the second, and transmit that information. Over the internet, that's limited to about a millisecond with NTP (Network Time Protocol)

 

Anyway, the two sources in the US, as the site says, agree to better than a microsecond. But the USNO follows the BIPM (the International standard) a little more closely. But then, we contribute upwards of half of the data that they collect.

 

edit to add: and I always chuckle at the mention of "the" atomic clock. The time that gets disseminated from USNO is the averaging of dozens of atomic clocks.

[5614]

a question which has always bugged me... how can you measure a more precise second?

 

i mean, everyone who makes these clocks can tell how accurate it is, but how can you do that, it has to be too fast or too slow relative to something else, so how do you get the model or perfect second?

 

once you have that its easy to compare.