Talk:Speed of light

Template:WP1.0

Needs correction in article: "and associated fields (including electromagnetic radiation such as light) travel in vacuum." should be "a" vacuum.

Question

(Moved to bottom)

Much of our science is focused on the speed of light and the underlying fact that nothing with mass can exceed this speed. So how do we work in the fact that lightspeed is variable? does this mean that in vaccum one can move faster than light passing through water? By definition this is faster than light travel. Also, some galaxies relative to eachother move faster than the speed of light. But light is not relative. If a string were strung from one galaxy to the other, and since the speed of light is not relative, the string would be moving faster than light from that galaxy. How are we to answer this? DZ — Preceding unsigned comment added by 67.253.200.168 (talk) 19:31, 23 April 2012 (UTC)

Article talk pages are for discussions about the format and content of the article, not the subject. You can ask questions like these at the wp:reference desk/Science. - DVdm (talk) 19:55, 23 April 2012 (UTC)

Wrong Footnote? (108)

Article text: "Descartes speculated that if the speed of light were found to be finite, his whole system of philosophy might be demolished.[108]"

Footnote 108: ^ a b c MacKay, RH; Oldford, RW (2000). "Scientific Method, Statistical Method and the Speed of Light". Statistical Science 15 (3): 254–78. doi:10.1214/ss/1009212817.

However, when you click on the footnote link, the resulting page says nothing about Descartes. — Preceding unsigned comment added by 209.197.169.54 (talk) 01:29, 7 May 2012 (UTC)

I get something relevant if I click on the Historical background section. Materialscientist (talk) 01:42, 7 May 2012 (UTC)

Thank you Materialscientist.

But then should the footnote reference not be changed to http://sas.uwaterloo.ca/~rwoldfor/papers/sci-method/paperrev/node2.html ?

There are three places in the article that indicate footnote 108:

1) The Descarte one which should actually point to http://sas.uwaterloo.ca/~rwoldfor/papers/sci-method/paperrev/node2.html

2) Aristotle "light is due to the presence of something, but it is not a movement". This can be found at the new footnote reference

3) "This led Alhazen to propose that light must have a finite speed" I cannot find Alhazen at either http://sas.uwaterloo.ca/~rwoldfor/papers/sci-method/paperrev/ or at http://sas.uwaterloo.ca/~rwoldfor/papers/sci-method/paperrev/node2.html

Hm .. the problem lies in the coding of that LaTeX copy - if we link http://sas.uwaterloo.ca/~rwoldfor/papers/sci-method/paperrev/node2.html then we lose the table of contents. Thus I left a comment in ref. 108 instead, as a quick solution. Materialscientist (talk) 03:34, 7 May 2012 (UTC)

Not sure if I'm seeing a different layout than you. When I first go to the link, I have "Next: Historical Background" at the top of the page. Clicking on that link takes me to the wrong page for Descarte. But if instead I scroll down to the bottom, I see a list of links with two for "Historical Background". It is the second "Historical Background" link that is the correct one. But perhaps it's just my version of IE. At any rate, assuming you get to the node2 link, I don't think this takes care of the Alhazen reference... I don't see any reference to Alhazen at that link (see the three items listed above: Note 108 covers (1) and (2), but not (3) as far as I can see. — Preceding unsigned comment added by 209.197.169.54 (talk) 04:14, 7 May 2012 (UTC)

Upper limit

As I understand it, the Lorentz Factor is a coefficient derived from the fact that there's an upper limit. Therefore, saying that there's an upper limit because of the Lorentz Factor is like saying there's an upper limit because there's a upper limit... not very insightful/scientific.

Pakito15191 (talk) 06:44, 20 March 2013 (UTC)

The closest I can find in the article to saying that there is an upper limit because of the Lorentz Factor is, 'Since the γ factor approaches infinity as v approaches c, it would take an infinite amount of energy to accelerate an object with mass to the speed of light'. Is this what you are objecting to? Martin Hogbin (talk) 09:39, 20 March 2013 (UTC)

You are right. The factor is usually derived from the demands that (1) laws should be the same in inertial frames and (2) that light speed is invariant. Saying that there is an upper limit because of the factor, is just silly. I made a little correction to the text. Good find. - DVdm (talk) 13:18, 20 March 2013 (UTC)

Although I have no real objection to your change I do not think it was actually necessary. The original wording does not say that there's an upper limit because of the Lorentz Factor it merely points out how the LF shows that infinite energy is required to accelerate an object with rest mass to the SoL. It does not assert that this is 'because of' the LF, which is a meaningless statement in physics anyway. Martin Hogbin (talk) 14:04, 20 March 2013 (UTC)

DVdm's change is minor, but it makes it a wee bit more difficult for a nitpicker to intentionally misread the text, so I'm in favor of the rewording. Stigmatella aurantiaca (talk) 14:36, 20 March 2013 (UTC)

Error in Main Table

Under exact values, the numbers for metres per second and for kilometres per second are listed as the same. This should be corrected. — Preceding unsigned comment added by 69.51.218.38 (talk) 22:36, 20 March 2013 (UTC)

There is a difference. Look closer. - DVdm (talk) 16:28, 21 March 2013 (UTC)

Yeah. Just noticed it. My mistake. I think I need a new monitor... or a new set of eyes! Sorry :)