Talk:Speed of light

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Why Round?[edit]

What is the point in rounding the speed of light to 186,000 miles/sec? No one ever needs to know the number rounded, and if I'm wrong, they will be capable of knowing where the comma is and just saying "thousand" after that. An article about the speed should present it accurately. Because of this, one of my students got the incorrect number when searching speed of light through Google. It was correct in meters/sec but showed the incorrect miles/sec. Rounding it serves no constructive purpose. I see people have been fighting over that on the page, so I'm not going to participate in that war, but I am going to say this is harmful. Doczilla @SUPERHEROLOGIST 08:22, 2 March 2017 (UTC)

The infobox has a number of approximate expressions with 3 significant digits, which is clearly marked. The opening sentence of the lead says: "Its exact value is 299792458 metres per second (approximately 3.00×108 m/s, approximately 186,282 mi/s)". We can't list an exact value in mi/s in the infobox, because there isn't one, alas—see note 3. Besides... who uses miles anyway? Face-smile.svg. - DVdm (talk) 08:35, 2 March 2017 (UTC)
Liberia and Myanmar use miles, and one other backwater country whose name escapes me at the moment... Stigmatella aurantiaca (talk) 18:44, 3 March 2017 (UTC)
Mile#Comparison table aka OUCH! Face-wink.svg - DVdm (talk) 19:10, 3 March 2017 (UTC)

speed of light not a constant ...[edit]

here's a little conumdrum ... not sure if my reasoning is correct but it sounds right to me ...

interresting bit of logic .... the speed of light as we all have been taught is a constant .... now here's the problem ... NASA proved that time goes slower the faster you go ... they did this during the apollo missions btw.. the astronauts watches were slower than the nasa clocks that's why they always used nasa time in the flight schedule ...

since time is not fixed in relation to velocity and velocity is Meters per second squared ... as your velocity approaches the observed speed of light time approaches infinitly small ... so infinty squared is a REALLY huge number ... and any speed measured in Meters unless infinity squared must be very very small .. or small enough to be as close to zero as you can get ... therefore the speed of light when measured at the same velocity as the light must be 0 (zero)

so if the speed of light is zero at fast speeds and it has a speed at our speed it cannot be a constant because it is not invariable ... it varies with the change in velocity because time changes in relation to velocity ...

and now you know why light bends and the speed of light is only constant at a specified velocity that does not equal a measured value of the speed of light.

btw this can also explain why the super colliders have such hard time working with subatomic particles .. because the particles they smash together are approaching the speed of light so the time they are using is inaccurate by a factor of the difference of the speed of the particles they are using times our measured value for the speed of light

not saying im right but this does make one go Hmmm — Preceding unsigned comment added by (talk) 19:57, 31 March 2017 (UTC)

? What the heck are you talking about? Do you not understand relativity or are you trying to be funny? --MC — Preceding unsigned comment added by (talk) 20:03, 18 April 2017 (UTC)


Not that this is a major thing but ...

Currently the phrase

299792458 metres per second

is bolded in the lead. DVdm argues this is because that phrase is an alternative "title" for the article (recall MOS states that only the title and its alternatives should be bolded). Granted, mathematically the speed of light is equivalent to this. But it is nonsense to argue that this is a "title" for this topic. It would be similarly nonsense to argue that "ratio of a circle's circumference to its diameter" is an alternative title for Pi. These are definitions of the topics, but to describe them as "titles" is silly. Given that logic we could bold numerous phrases in every lead section of every article.

-- MC — Preceding unsigned comment added by (talk) 20:11, 18 April 2017 (UTC)

I have rebolded it per MOS:BOLDSYN, as this is part of the definition, and effectively a synonym of the article subject. Unless there is a consensus to change it, let's keep it the way it was per wp:NOCONSENSUS: In discussions of proposals to add, modify or remove material in articles, a lack of consensus commonly results in retaining the version of the article as it was prior to the proposal or bold edit - DVdm (talk) 20:50, 18 April 2017 (UTC)
Additional issue: DVdm is now insisting on including a link in this bolded phrase, an even more direct violation of MOS. -- MC
BTW, DVdm, please bear in mind WP:TALKDONTREVERT and be careful about trying to twist WP guidelines to justify something they are not intended to allow. In general MOS should be followed unless there is a truly exceptional situation. -- MC — Preceding unsigned comment added by 2605:6000:EC25:EF00:9165:DAEC:E3C9:D623 (talk) 04:15, 19 April 2017 (UTC)
Please sign all your talk page messages with four tildes (~~~~) and indent the messages as outlined in wp:THREAD and wp:INDENT. Also, please consider signing up for a username. Thanks.
This is an exceptional situation: if you read the article, you will see that the speed of light is indeed defined as 299 792 458 metres per second, so we are following MOS here. - DVdm (talk) 09:05, 19 April 2017 (UTC)
DVdm, you are confusing title and definition. The relevant question is whether the phrase is a reasonable alternative title. This is closely related to the question whether the phrase should redirect here (which in this case it does not). (This is BTW part of the background of this requirement of the MOS. Self-wikilinks by default automatically appear in black bold. For technical reasons redirects to the current page do not, hence the MOS requires this formatting to be included manually.) We can now have the discussion whether 299792458 metres per second should redirect here. I have no strong opinion on that matter, although I'd lean to 'probably not'.TR 13:04, 19 April 2017 (UTC)
I agree that the relevant question is whether the phrase is a reasonable alternative title, and I'd argue that it is indeed. Ok if I create a redirect article 299792458 metres per second pointing here? - DVdm (talk) 13:32, 19 April 2017 (UTC)
Do you think that, that is a likely title anybody would search for? Is there anybody that remembers 9 digits of the speed of light, but no that it is the speed of light? (again I don't have a strong opinion on this either way.)TR 07:38, 20 April 2017 (UTC)
Apparently, 299,792,458 metres per second already exists as a redirect, and has existed since 2008 ...TR 07:41, 20 April 2017 (UTC)
Heh, that's probably the reason why the bolding was put there to begin with Face-smile.svg. - DVdm (talk) 08:20, 20 April 2017 (UTC)
Yep, September 2013: "Bold the number, which is important, and which redirects here. WP:MOSBOLD" Looks like a long standing thing. DVdm (talk) 08:30, 20 April 2017 (UTC)
All this says is that Srleffler made the same mistake you did. There is no rule that says if a redirect points to a page then the title of the redirect should be bolded in the page. There are many redirects that are simply misspellings of article titles. Does this mean we add every possible misspelling of an article title to the page and bold it?
Regardless, as TR says, "you are confusing title with definition". There is no exceptional reason to violate MOS here. The pi article does not bold "ratio of a circle's circumference to its diameter", the speed of sound article does not bold "distance travelled per unit time by a sound wave as it propagates through an elastic medium", and the light-year article does not bold "distance that light travels in vacuum in one Julian year". MOS should be adhered to here, period. -- MC — Preceding unsigned comment added by (talk) 18:05, 24 April 2017 (UTC)
I stil don't think there is a consensus to change the long-standing version. See wp:NOCONSENSUS. - DVdm (talk) 18:11, 24 April 2017 (UTC)
I don't have a strong opinion either way, but given this is an exact value, which is of rather high importance in metrology and in scientific education, I'm fine with bolding it in the lead. Headbomb {t · c · p · b} 18:22, 24 April 2017 (UTC)


The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

This discussion is closed, per WP:SNOW!

An editor has asked for consensus input so I am putting out an RFC. The issue is simply the bolding of the phrase "299792458 metres per second" in the lead paragraph and the accompanying addition of a link in the boldfaced phrase. The concern is violations of MOS:BOLD and MOS:BOLDAVOID. (Disclaimer: I realize this is a relatively trivial matter and I am uncertain why the fix is controversial). --MC (talk) 19:15, 25 April 2017 (UTC)

  • Remove the boldface: This phrase is not a title but rather a definition. It is an MOS:BOLD violation to boldface it. If the boldface were to be preserved, then the link would need to be removed per MOS:BOLDAVOID. There is nothing exceptional about this particular situation so no justifiable reason to go against MOS. -- MC (talk) 19:15, 25 April 2017 (UTC)
  • Keep boldface per my above post. Headbomb {t · c · p · b} 20:21, 25 April 2017 (UTC)
  • Remove the boldface: Although I do not see the use of bold as explicitly against any recommendations in MOS:BOLD and MOS:BOLDAVOID, it appears to me to be against the "spirit" of the recommendations. Stigmatella aurantiaca (talk) 20:34, 25 April 2017 (UTC)
  • Keep boldface as a synonym of the article name and fully in line with the spirit of wp:BOLDSYN. - DVdm (talk) 20:42, 25 April 2017 (UTC)
  • Remove. It doesn't seem to be a true synonym to me. The numerical value of something isn't the same as the thing's name or description. Can anyone find a text book that doesn't use the phrase "speed of light" but instead uses the phrase "299792458 metres per second" throughout? Would you also add "1 light-second per second" and put that in bold, too? (Also "the speed of light is 299792458 metres per second" is not a definition of the speed of light; it's a definition of the metre.) -- Dr Greg  talk  23:56, 25 April 2017 (UTC)
  • Remove boldface. The numerical value is not an alternative title. The speed of light is a conceptual quantity, and the numerical value in meters is a description of that quantity in terms of another quantity. CapitalSasha ~ talk 04:38, 26 April 2017 (UTC)
  • Remove. Actually I am perfectly happy to keep it bolded, but the justification is tenuous and it is just the kind of triviality that leads futilely to walls of text. Anyway, if anyone looks up the number as a title, the redirect gets you here and remarks on the redirection, so the bolding serves little purpose. So I say count the votes and follow the narrower rules. JonRichfield (talk) 08:25, 26 April 2017 (UTC)
  • Remove this is the definition of a metre; to suggest it is also the definition of the speed of light is clearly circular. Porphyro (talk) 11:14, 27 April 2017 (UTC)
  • Remove boldface. I agree with JonRichfield. The issue isn't worth arguing about. But now I'm here, I have to say that the number is not a commonly-used synonym for "speed of light". Maproom (talk) 05:53, 28 April 2017 (UTC)
  • Remove. This opinion is well established already, but this appears to be completely unnecessary. This may be the result of applying "To follow the 'principle of least astonishment' after following a redirect, for terms in the first couple of paragraphs of an article, or at the beginning of a section of an article, which are the subjects of redirects to the article or section (e.g. sub-topics of the article's topic, rather than the synonyms as already boldfaced per the above)" from MOS:BOLD, but this seems unlikely to actually violate the principle of least astonishment. --tronvillain (talk) 20:53, 28 April 2017 (UTC)
  • Remove the boldface. We do not bold links, and it is not a synonym for the article title. We would not bold the phrase "official residence of the president of the United States of America" in the White House article. Quantum Burrito (talk) 10:21, 30 April 2017 (UTC)
  • Remove and I request/suggest the RFC be withdrawn or Snow-closed early. We really don't need to sink more editor's time into this. Every uninvolved arrival to the RFC is saying 'remove'. Alsee (talk) 06:32, 1 May 2017 (UTC)

Closing the RFC discussion, per WP:SNOW. The nearly unanimous decision is to remove the bold.

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

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