Talk:Atomic clock

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Definition of the Second

The history of the second has changed as atomic clocks have become more accurate. I understand that some of the definitions about the atomic clock from the BIPM are official and the want to remove them, but I think its good to understand the evolution of clocks from mechanical instruments such as grandfather clocks to marine chronometers to quartz watches to the first atomic clock. ScientistBuilder (talk) 01:58, 26 February 2022 (UTC)

Only atomic clocks are accurate enough, over a period of weeks or greater, to serve as the definition of the second. Before the mid-to-late 20th century the second was defined in astronomical terms. Mechanical and quartz clock were used as devices to record the times of astronomical observations in the short term, but were steered in one way or another to agree with the astronomical observations. Jc3s5h (talk) 02:49, 26 February 2022 (UTC)

Also, we already have the articles Clock, History of clocks, History of timekeeping devices, and Time metrology which cover these topics. --Chetvorno^TALK 07:03, 26 February 2022 (UTC)

I propose adding this table to the article.

== History of Definition ==

Evolution of the Second
Decisions of the CIPM	Resolution of the CGPM	Information
That according to the decisions of the 8th General Assembly of the International Astronomical Union (Rome, 1952), the second of ephemeris time (ET) is the fraction ${\frac {12960276813}{408986496}}\times 10^{-9}$ of the tropical year for 1900 January 0 at 12 h ET.	The second is the fraction ${\frac {1}{31556925.9747}}$ of the tropical year for 1900 January 0 at 12 hours ephemeris time.	1956 CIPM 11th CGPM 1960 Resolution 9
The standard to be employed is the transition between the hyperfine levels F=4, M=0 and F=3, M=0 of the ground state $^{2}S_{1/2}$ of the caesium 133 atom, unperturbed by external fields, and that the frequency of this transition is assigned the value 9192631770 hertz.	The second is 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	13th CGPM Resolution 1 CIPM 1964
This definition implies that the caesium atom is at rest and unperturbed. In consequence, in its practical realization, measurements must be corrected for velocity of the atoms with respect to the clock reference frame, for magnetic and electric fields including ambient black-body radiation, for spin-exchange effects and for other possible perturbations.	At its 1997 meeting, the CIPM affirmed that: This definition refers to a caesium atom at rest at a temperature of 0 K. This note was intended to make it clear that the definition of the SI second is based on a Cs atom unperturbed by black-body radiation, that is, in an environment whose temperature is 0 K, and that the frequencies of primary frequency standards should therefore be corrected for the shift due to ambient radiation, as stated at the meeting of the CCTF in 1999.	footnote added by the14th meeting of the Consultative Committee for Time and Frequency in 1999 the footnote was added at the 86th (1997) meeting of the CIPM GCPM 1998 7th Edition SI Brochure
The definition of a unit refers to an idealized situation that can be reached in the practical realization with some uncertainty only. In this spirit, the definition of the second has to be understood as referring to atoms free of any perturbation, at rest and in the absence of electric and magnetic fields. A future re-definition of the second will be justified if these idealized conditions can be achieved much easier than with the current definition. The definition of the second should be understood as the definition of the unit of proper time: it applies in a small spatial domain which shares the motion of the caesium atom used to realize the definition. In a laboratory sufficiently small to allow the effects of the non-uniformity of the gravitational field to be neglected when compared to the uncertainties of the realization of the second, the proper second is obtained after application of the special relativistic correction for the velocity of the atom in the laboratory. It is wrong to correct for the local gravitational field.	The second, symbol s, is the SI unit of time. It is defined by taking the fixed numerical value of the caesium frequency, $\Delta v_{Cs}$, the unperturbed ground-state hyperfine transition frequency of the caesium 133 atom, to be 9 192 631 770 when expressed in the unit Hz, which is equal to $s^{-1}$. The reference to an unperturbed atom is intended to make it clear that the definition of the SI second is based on an isolated caesium atom that is unperturbed by any external field, such as ambient black-body radiation. The second, so defined, is the unit of proper time in the sense of the general theory of relativity. To allow the provision of a coordinated time scale, the signals of different primary clocks in different locations are combined, which have to be corrected for relativistic caesium frequency shifts (see section 2.3.6). The CIPM has adopted various secondary representations of the second, based on a selected number of spectral lines of atoms, ions or molecules. The unperturbed frequencies of these lines can be determined with a relative uncertainty not lower than that of the realization of the second based on the 133Cs hyperfine transition frequency, but some can be reproduced with superior stability.	Current Definition resolved in 2018 effective after the 26th GCPM approved the redefinition May 20 2019. SI Brochure 9

ScientistBuilder (talk) 03:08, 26 February 2022 (UTC)

I don't think any of this belongs in this article. This article is about atomic clocks, not about the second. You have already added this table to the second article, so there's no need to repeat it here; we can just link to second. Furthermore, much of this table has nothing whatsoever to do with atomic clocks. CodeTalker (talk) 03:14, 26 February 2022 (UTC)

Agree with CodeTalker. The readable prose length of the article is already 51kb, and there is a lot more about atomic clocks that needs to be added. It looks like you have just taken the long quotes that were in the History section and put them in this table, along with additional material. --Chetvorno^TALK 06:51, 26 February 2022 (UTC)

I am not in favor of complicated tables being maintained in more than one place. Wikipedia is not a static place. If the table exists in more than one place, over time, they will come to have different information. I am also not in favor of tables with large amounts of prose in the boxes. Constant314 (talk) 13:46, 26 February 2022 (UTC)

@Constant314: Is there a way to display a wikitable defined in one article in another article? --Chetvorno^TALK 18:14, 26 February 2022 (UTC)

@Chetvorno:I think that the answer is yes. It involves creating a template and then invoking the template. But, in this case, I think that it would be better to just create and article called "History of the second" and then wikilink to it. I'll drop an example on your talk page. Constant314 (talk) 22:16, 26 February 2022 (UTC)

I'll leave that to you all. --Chetvorno^TALK 22:32, 26 February 2022 (UTC)

I don't understand why you propose it here, then one minute later just make the change anyway. Just make the change, or let your proposal come to a conclusion. Personally I think this should be rolled back Strangerpete (talk) 16:01, 26 February 2022 (UTC)

@Constant314: your edit has created a contradiction. In the "Definition of the second" subsection of the "History" section, you indicate the second was defined in terms of atomic clocks in 2019 (which is wrong by decades). But the "Optical clock advances" section claims " caesium clocks have been keeping time since the definition of the second in 1960" which is also wrong. Jc3s5h (talk) 18:28, 26 February 2022 (UTC)

It was my interpretation of that very long table. It looked like the second wasn't officially redefined until 2019. It looked like everything prior to that was a recommendation. Constant314 (talk) 18:33, 26 February 2022 (UTC)

You can't trust a table that appears in Wikipedia. According to McCarthy & Seidelmann (1960 2009, full citation in article) p. 195, the 13th CGPM (1967-1968) redefined the second as "the duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom." The later redefinitions were refinements, where such things as the temperature and the location of the clocks were specified. Jc3s5h (talk) 19:51, 26 February 2022 (UTC)

Please change the date as you see to be correct. It looks like you mistyped something in your comment. It appears that McCarthy & Seidelmann published in 1960 is being cited for something that happened in 1967. Constant314 (talk) 20:26, 26 February 2022 (UTC)

Organization

I want to index the article like this:

1. Definition of second

1. History and development and how Caesium clocks work including normal caesium clocks and primary standard caesium clocks such as NIST-F2

1. History and Development and how Optical Clocks Work

1. Ways to Redefine the second with sections on the Rydberg constant, Optical clocks

Applications like How Atomic Clocks keep International Time and work with GPS and timestamp financial transactions ScientistBuilder (talk) 03:29, 26 February 2022 (UTC)

@ScientistBuilder: This is a proposed outline of the whole article? If so, it seems to me some essential topics are left out. Where are hydrogen and rubidium clocks described? Also, as mentioned before, I think the "Ways to redefine the second" section is off-topic in this article.

Some technical notes:

• Unless they have proper nouns, only the first letter of section titles should be capitalized (MOS:SECTIONHEAD)
• In the above list, the reason the numbering operator, #, didn't work right is due to the spaces between the lines.

--Chetvorno^TALK 06:31, 26 February 2022 (UTC)

Split

I think the article should be split because the article is 131843 bytes or 131.843 kilobytes as of the time this post was made.

Wikipedia:SIZERULE states

article size> 100 kB Almost certainly should be divided

I propose making optical atomic clock a separate article. ScientistBuilder (talk) 17:09, 22 June 2022 (UTC)

My edit 2022-09-06 08:17

I replaced 'frequency of radiation of atoms' by 'resonant frequency of atoms' because, AFAIK, rubidium frequency references (and hence rubidium atomic clocks) work by finding an absorption-maximum frequency (6834682610.904 Hz). The term 'resonant frequency of atoms' is intended to cover both emission and absorption phenomena.

Dulciana (talk) 08:23, 6 September 2022 (UTC)

My edit 2022-09-06 13:12

The BIPM Time Department Database https://webtai.bipm.org/database/showlab.html lists more than 80 laboratories whose atomic clocks contribute to UTC. I would hesitate to call this a 'small number'.

Dulciana (talk) 13:15, 6 September 2022 (UTC)

My edit 2022-09-07 06:33

Without corroborating information, citations etc., this section was imprecise. For example, it is implied that hydrogen maser clocks are less expensive than caesium clocks. The Wikipedia page 'Hydrogen maser' quotes a price 'as much as 235,000 USD'; AFAIK commercial caesium clocks are much cheaper. The statement 'The power consumption of atomic clocks varies with their size' also requires examples, citations etc.

Dulciana (talk) 06:49, 7 September 2022 (UTC)

Article issues and clarification

There are several unsourced paragraphs that contain content requiring sourcing. Paragraphs in the "International timekeeping" subsection are somewhat technical and unsourced. The same with the "Clock mechanism" subsection especially the last paragraph. The "Redefining the second" section has unsourced sentences and paragraphs.

The "External links" section has 14 entries. Three seems to be an acceptable number and of course, everyone has their favorite to add for four. The problem is that none is needed for article promotion.

• ELpoints #3) states: Links in the "External links" section should be kept to a minimum. A lack of external links or a small number of external links is not a reason to add external links.
• LINKFARM states: There is nothing wrong with adding one or more useful content-relevant links to the external links section of an article; however, excessive lists can dwarf articles and detract from the purpose of Wikipedia. On articles about topics with many fansites, for example, including a link to one major fansite may be appropriate.
• WP:ELMIN: Minimize the number of links. --

The B-class criteria states: The article is suitably referenced, with inline citations. It has reliable sources, and any important or controversial material which is likely to be challenged is cited. -- Otr500 (talk) 23:13, 26 February 2023 (UTC)

I agree. None of them met WP guidelines and have been removed. Constant314 (talk) 01:23, 27 February 2023 (UTC)

Cloned section

See Talk:Second so as to not clone a discussion in addition to the section. Nerdwizard (talk) 04:35, 10 April 2023 (UTC)

AddedHomeMappedDatas

TalkingsACPhonedDatasAdded@133CaesiumLnkedDatasPublishmentSubmitter ShaileshPrasad AutoRog5sPhonesDatas@7/4/2023ISTC 2405:201:A409:DBB6:29A0:AD22:5C6D:4A9 (talk) 07:34, 7 May 2023 (UTC)

This looks like code. What's it doing in Talk? What is it supposed to mean?

MrDemeanour (talk) 12:36, 7 May 2023 (UTC)