Revision history of "The speed of light"

This is a list of past revisions of The speed of light. Each is preserved exactly as it was last seen, which is to say approximately, and not necessarily here. Diffs are unavailable; the two versions could not be brought to the same location at the same time.

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• cur | prev 2026 NotTheMudGeometer (talk | contribs) . . (9,910 bytes) (+80) . . (STILL SAY YOU CAN NOT VOTE ON IT. AND THE ONE WAY SPEED HAS STILL NEVER BEEN MEASURED BY NO ONE, WHICH IS MY POINT, AND I SEE THE ARTICLE AGREES WITH ME) (current)
• cur | prev 2019 an editor (talk | contribs) . . (9,830 bytes) (+200) . . (→ the kilogram, the ampere, the kelvin and the mole have now gone the same way. this article's constant went first, thirty six years ahead of the rest of them)
• cur | prev 2017 an editor (talk | contribs) . . (9,630 bytes) (+260) . . (→ gravity travels at this speed too, to a few parts in a thousand million million. a neutron star merger and its gamma ray burst arrived one and three quarter seconds apart, after a hundred and forty million years of running side by side)
• cur | prev 2016 T. Vogel (talk | contribs) . . (9,370 bytes) (+190) . . (→ leaving that where it stands. what was voted on was the length of the metre and not the speed of anything, but the objection is the one this article exists to answer and it should be answered in the open)
• cur | prev 2016 MudGeometer_1844 (talk | contribs) . . (9,180 bytes) (+70) . . (THEY VOTED ON IT. YOU CAN NOT VOTE ON HOW FAST A THING GOES)
• cur | prev 2012 the IAU (talk | contribs) . . (9,110 bytes) (+280) . . (→ and the astronomical unit is now exactly 149,597,870,700 metres. Rømer's problem is formally inverted: the light time is the quantity we are sure of and the distance is what comes out of it)
• cur | prev 2012 the OPERA collaboration (talk | contribs) . . (8,830 bytes) (+300) . . (→ withdrawing it. a timing connector that was not seated, worth seventy three nanoseconds on its own, less an oscillator running fast the other way. the famous result was the residue of two faults)
• cur | prev 2011 the OPERA collaboration (talk | contribs) . . (8,530 bytes) (+340) . . (→ we have neutrinos arriving sixty nanoseconds early over seven hundred and thirty one kilometres. we do not believe it either. we are publishing the anomaly and asking for help with it, and not claiming a discovery)
• cur | prev 1999 an editor (talk | contribs) . . (8,190 bytes) (+230) . . (→ added the slow light. seventeen metres a second through a cold gas at Harvard, which is sixty one kilometres an hour. it is the group velocity and not the light, and the article had better say so twice)
• cur | prev 1991 G. Hopper (talk | contribs) . . (7,960 bytes) (+170) . . (→ added the wire. it is eleven point eight inches long and it is one nanosecond, and it explains the pause on a satellite call to an admiral faster than the arithmetic does)
• cur | prev 1983 an editor (talk | contribs) . . (7,790 bytes) (−130) m . . (→ removed the section on improving the accuracy. there is nothing left in it to improve)
• cur | prev 1983 the 17th CGPM (talk | contribs) . . (7,920 bytes) (+400) . . (→ resolved. the metre is henceforth the distance light travels in one part in 299,792,458 of a second, so the speed is exact and this article's central figure has stopped being a measurement. removing the error bar)
• cur | prev 1975 the 15th CGPM (talk | contribs) . . (7,520 bytes) (+200) . . (→ recommending 299,792,458 as the value to be used everywhere. not yet a definition. one step short of it)
• cur | prev 1973 an editor (talk | contribs) . . (7,320 bytes) (+140) m . . (→ so the ruler is the blurred part now. either somebody makes a better metre or we stop measuring this altogether. flagging it for the conference)
• cur | prev 1972 the Bureau of Standards (talk | contribs) . . (7,180 bytes) (+480) . . (→ multiplied the frequency by the wavelength: 299,792,456.2, a hundredfold improvement in one step. note that the uncertainty left in it is not in our apparatus. it is in the krypton line that defines the metre)
• cur | prev 1967 the CGPM (talk | contribs) . . (6,700 bytes) (+190) . . (→ and the second stops being a fraction of a day. it is caesium, which is his clock. these two definitions will have to meet each other eventually)
• cur | prev 1960 the CGPM (talk | contribs) . . (6,510 bytes) (+240) . . (→ the metre stops being a bar. it is a number of wavelengths of a krypton line now, for the reasons set out at Le Grand K)
• cur | prev 1955 an editor (talk | contribs) . . (6,270 bytes) (+200) . . (→ restored his figure. it turns out to improve the radar ranging, which has persuaded people where five years of argument did not)
• cur | prev 1955 L. Essen (talk | contribs) . . (6,070 bytes) (+260) . . (→ built a clock while waiting. caesium, at the National Physical Laboratory, and it keeps better time than the earth does)
• cur | prev 1951 L. Essen (talk | contribs) . . (5,810 bytes) (+150) . . (→ then let the article carry both figures, and let the reader notice that the error bars do not overlap. that is the whole of my case)
• cur | prev 1951 an editor (talk | contribs) . . (5,660 bytes) (−180) . . (→ reverted to the accepted value. one determination against twenty years of agreement is not sufficient)
• cur | prev 1950 L. Essen (talk | contribs) . . (5,840 bytes) (+320) . . (→ 299,792.5, from a resonant cavity and no light beam at all. sixteen and a half above the accepted value and four times outside the error attached to it)
• cur | prev 1941 R. Birge (talk | contribs) . . (5,520 bytes) (+210) . . (→ adopting 299,776 plus or minus four. the determinations of the last twenty years agree closely with one another, which is the whole of my reason for it)
• cur | prev 1935 F. Pease (talk | contribs) . . (5,310 bytes) (+460) . . (→ finished it without him. two hundred and thirty three determinations in all, and the mean is 299,774, which is worse than his open-air figure of 1926 and disagrees with it by twenty two. we could never pump it hard enough, and the water in the ditch alongside moved the readings)
• cur | prev 1931 A. Michelson (talk | contribs) . . (4,850 bytes) (+300) . . (→ begun in the tube at Irvine. a mile of pipe three feet across, pumped down, the beam folded until it has run ten miles. thirty six determinations so far)
• cur | prev 1926 A. Michelson (talk | contribs) . . (4,550 bytes) (+230) . . (→ 299,796, over the twenty two miles between Mount Wilson and Mount San Antonio. i do not expect to better it by much in open air)
• cur | prev 1905 A. Einstein (talk | contribs) . . (4,320 bytes) (+350) . . (→ removed the medium properly. the speed does not require something to be the speed in, and once it is the same for everybody the rest follows. it is now an assumption of the article and not a finding)
• cur | prev 1887 A. Michelson (talk | contribs) . . (3,970 bytes) (+210) . . (→ and the aether is not there. that belongs to another article, but it removes the medium this speed was supposed to be a speed in)
• cur | prev 1879 A. Michelson (talk | contribs) . . (3,760 bytes) (+180) . . (→ my first, from the Naval Academy, with a rotating mirror and almost no money. i expect to spend some years on this)
• cur | prev 1863 the Mud Geometer (talk | contribs) . . (3,580 bytes) (+60) . . (SO THE LIGHT IS ELECTRICAL NOW. LAST WEEK IT WERE WAVES IN A JELLY. PUT IT BACK)
• cur | prev 1862 J. C. Maxwell (talk | contribs) . . (3,520 bytes) (+420) . . (→ added the electrical derivation. two men with a capacitor and a galvanometer, thinking about no light whatever, have arrived at the same number. we can scarcely avoid the inference)
• cur | prev 1862 L. Foucault (talk | contribs) . . (3,100 bytes) (+190) . . (→ 298,000 with the turning mirror, over a path short enough to fit indoors. low by six parts in a thousand, though there is nothing yet to say so against)
• cur | prev 1850 L. Foucault (talk | contribs) . . (2,910 bytes) (+220) . . (→ and slower in water than in air, which decides between the two theories of light and is the more useful result. the speed itself is still some per cent out)
• cur | prev 1849 H. Fizeau (talk | contribs) . . (2,690 bytes) (+380) . . (→ done on the ground at last. a wheel of seven hundred and twenty teeth and a mirror at Montmartre, and no part of it wants anything from the sky. 313,274)
• cur | prev 1729 J. Bradley (talk | contribs) . . (2,310 bytes) (+240) . . (→ eight minutes and twelve seconds from the Sun, arrived at by failing to find the parallax i was looking for. this is also a duration, and i note that we have still not measured a speed)
• cur | prev 1704 I. Newton (talk | contribs) . . (2,070 bytes) (+150) . . (→ adopted it, and note that the objection from the observatory has quietly lapsed. whatever light is made of, it takes time to arrive)
• cur | prev 1690 C. Huygens (talk | contribs) . . (1,920 bytes) (+280) . . (→ divided it. taking the orbit at twenty four thousand diameters of the Earth, light goes about a thousand diameters in the minute. the observation is his and the number is mine, and the article should keep saying which is which)
• cur | prev 1677 O. Rømer (talk | contribs) . . (1,640 bytes) (+160) . . (→ i do not know how wide the orbit is, and neither does anybody else. the duration is what was measured and the duration is what the article will say)
• cur | prev 1676 an editor (talk | contribs) . . (1,480 bytes) (+90) m . . (→ he has given a duration and no speed. asking whether he means to divide it by something)
• cur | prev 1676 G. D. Cassini (talk | contribs) . . (1,390 bytes) (+170) . . (→ the observatory does not endorse this. the moon Io is irregular for reasons of its own, and the other three satellites do not show the effect as plainly as they ought)
• cur | prev 1676 O. Rømer (talk | contribs) . . (1,220 bytes) (+470) . . (→ the eclipses of Jupiter's moon run early when we are coming towards him and late when we are going away, and the difference gathers across the year. i make it about twenty two minutes for light to cross the width of our own orbit)
• cur | prev 1667 the Accademia del Cimento (talk | contribs) . . (750 bytes) (+130) m . . (→ we repeated the lantern trial over about a mile and learned precisely what he learned. leaving the section where it is)
• cur | prev 1644 R. Descartes (talk | contribs) . . (620 bytes) (+200) . . (→ it is instantaneous, and the eclipses of the moon prove it: were light slow we should see the sun, the earth and the moon out of line, and we do not)
• cur | prev 1638 G. Galilei (talk | contribs) . . (420 bytes) (+420) . . (created page; two men on facing hilltops with shuttered lanterns. if light takes time to cross between them i cannot detect it, and i will say only that it is either instantaneous or exceeding quick)

Older revisions exist but have not been located. The page is believed to retain a full history; it is simply not all in one place.