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Author Topic: How do scientists set a atomic clock?  (Read 4561 times)

Phil Crane

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How do scientists set a atomic clock?
« on: 07/07/2011 16:01:01 »
Phil Crane  asked the Naked Scientists:
   
Hi,

I have a question for you regarding atomic clocks.

I've always wondered how scientists set the time on a newly built atomic clock (assuming that they do!) Any attempt to set the time from an existing atomic clock would not be instantaneous and thus the new clock would be set with the wrong time. How was the time set on the very first clock, who decided what the current time was down to the nearest fraction of a millisecond?

thanks,
love the show,
Phil from Sacramento, CA

What do you think?
« Last Edit: 07/07/2011 16:01:01 by _system »


 

Offline Mr. Data

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How do scientists set a atomic clock?
« Reply #1 on: 07/07/2011 23:33:51 »
No one really set up a physical atomic clock; we say particles which experience time act like clocks because of time dilation. I'm not sure what you mean by ''who decided what the current time was down to the nearest fraction of a millisecond?''

You might be thinking of the Planck Time? I don't know, but this is a very short instant of time - one of the smallest we can experimentally reach.



http://arxiv.org/PS_cache/arxiv/pdf/0802/0802.3227v1.pdf
 

Offline JP

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How do scientists set a atomic clock?
« Reply #2 on: 08/07/2011 00:52:13 »
No one really set up a physical atomic clock; we say particles which experience time act like clocks because of time dilation. I'm not sure what you mean by ''who decided what the current time was down to the nearest fraction of a millisecond?''

You might be thinking of the Planck Time? I don't know, but this is a very short instant of time - one of the smallest we can experimentally reach.



http://arxiv.org/PS_cache/arxiv/pdf/0802/0802.3227v1.pdf

I think what the original poster is referring to is an atomic clock: http://en.wikipedia.org/wiki/Atomic_clock

Part of the answer is that atomic clocks designed to be very good at measuring time because they rely on atomic transitions which are very precise.  I'm not sure how they synchronize them, but there is one "master clock" at NIST, for example, which defines the official time for the US.  I assume other countries have their own standards.
 

Offline Geezer

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How do scientists set a atomic clock?
« Reply #3 on: 08/07/2011 01:03:47 »
I suppose they are all ultimately synchronized with astronomical observations as the Earth orbits the Sun. From time-to-time (:)) it's necessary to add or subtract a few seconds to keep the clocks in sync with the Earth.

If I remember rightly, the official standard is actually derived by averaging the results from several atomic clocks.
 

Offline Mr. Data

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How do scientists set a atomic clock?
« Reply #4 on: 08/07/2011 03:00:21 »
No one really set up a physical atomic clock; we say particles which experience time act like clocks because of time dilation. I'm not sure what you mean by ''who decided what the current time was down to the nearest fraction of a millisecond?''

You might be thinking of the Planck Time? I don't know, but this is a very short instant of time - one of the smallest we can experimentally reach.



http://arxiv.org/PS_cache/arxiv/pdf/0802/0802.3227v1.pdf

I think what the original poster is referring to is an atomic clock: http://en.wikipedia.org/wiki/Atomic_clock

Part of the answer is that atomic clocks designed to be very good at measuring time because they rely on atomic transitions which are very precise.  I'm not sure how they synchronize them, but there is one "master clock" at NIST, for example, which defines the official time for the US.  I assume other countries have their own standards.

Oh yes... of course. :)
 

Offline imatfaal

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How do scientists set a atomic clock?
« Reply #5 on: 08/07/2011 11:15:07 »
I belive they are ultimately synchronized with each other using amongst other things the array of GPS satellites.  Atomic clock accuracy is phenomenal and you are right to query the lack simulteneity for clocks that are physically seperate.  However we can calculate very accurately the time differences caused by seperation around the globe and this is accounted for.  As an anecdotal example of the mindbending accuracy - the atomic clocks in Colorado (Boulder I think but perhaps Denver) have to be calibrated slightly differently from those in Rhode Island due to the time dilation effect caused by differing heights above sea level.  The guys who work to these standards of accuracy are well equiped to make adjustments for time of transmission of time signal
 

Offline syhprum

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How do scientists set a atomic clock?
« Reply #6 on: 08/07/2011 11:23:23 »
Basically atomic clocks are not really clocks but very stable signal generators, it is up to the world standard authority's to derive a synchronised time system from them
 

Offline yor_on

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How do scientists set a atomic clock?
« Reply #7 on: 09/07/2011 00:46:23 »
 

Offline Bored chemist

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How do scientists set a atomic clock?
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