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The rationale behind the request is: "The speed of light is central to physics fields including the Big Bang Theory, special relativity, general relativity, spectroscopy, optics, as well as real world applications such as signal processing and GPS networks".
The speed of light is approximately 300,000 kilometres per second; 186,000 miles per second; 671 million miles per hour.
The metric measurement should include 1.08 billion kilometres per hour, to be consistent with metric and imperial examples.
Eiger3970 (
talk)
07:36, 5 September 2023 (UTC)reply
Is this part accurate in History?
Quote:
Connections with electromagnetism
In the 19th century Hippolyte Fizeau developed a method to determine the speed of light based on time-of-flight measurements on Earth and reported a value of 315000 km/s (704,634,932 m/h).
Are you suggesting our article may not be correct or proposing that it include conversions to km/h at that point, and in either case, why?
NebY (
talk)
11:07, 18 November 2023 (UTC)reply
Indeed, but the values in parentheses aren't in the article. If we wanted to include them, we could use {{Convert}}, which would probably round them appropriately automatically, and wouldn't abbreviate miles to "m" either, but I don't see why we'd want to include such conversions in that part of the article anyway.
NebY (
talk)
13:46, 18 November 2023 (UTC)reply
Why not also include an accurate description of c in miles per second?
186282.3970512 mi/s, to be fairly accurate.
Speed of light in vacuum
Wikipedia should get rid of all occurrences of the phrase "speed of light in vacuum". There is only one speed of light, which is a universal constant. Also the speed of light doesn't change if not in vacuum.
Group velocity represents the real speed of a photon, and that doesn't change. Only
phase velocity is changing, causing the optical effects that mislead people. But this very article is explaining the same in the section
Speed of light#In a medium.
Lustakutya (
talk)
13:24, 20 May 2024 (UTC)reply
Sometimes c is used for the speed of waves in any material medium, and c0 for the speed of light in vacuum.[1] This subscripted notation, which is endorsed in official SI literature[2] ....
This is what I was talking about from the beginning. You are confusing two different concepts as well. c0 has a place in physics. In one place. Optics. In case of refraction the phase velocity is used for calculations, because the phase of light is shifting constantly if travelling in a medium which is not vacuum. Every other area of physics is using the universal constant c, which can be calculated using
Maxwell's equations. By the way the
Photon article also says "Photons are massless particles that always move at the speed of light when in vacuum." which is plain wrong. Photons are unable to travel slower then c.
That's a great video. But it's not news, sorry. It explains the atomic model of the index of refraction. Based on this video I recommend no changes.
Johnjbarton (
talk)
17:58, 20 May 2024 (UTC)reply