Physics Help Forum THE speed of light in sofar as the determination is

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 May 1st 2018, 01:48 PM #1 Banned   Join Date: Apr 2018 Posts: 92 THE speed of light in sofar as the determination is Roemer (1676) is accredited as the first to measure the velocity of light but Roemer's calculation of the velocity of light is based on Io forming four eclipses at L, K, F and G but Roemer does not indicate the dates of all four eclipses that are used to calculate the velocity of light since it is highly unlikely that Io can form the four eclipses at precisely the dates used to calculate the velocity of light. Huygens (1690) measurement of the velocity of light is based on Roemer's method. Bradley's (1729) stellar aberration is used to calculate the velocity of light but the change in the position of Bradley's star is caused by the earth's daily and yearly motions not the velocity of light since the shift in the position of Bradley's star results in the rotational positional shift of all the stars of the stellar universe that shift is centered around the North Star. Fizeau (1848) attempts to measure the velocity of light using a light beam that is incident to a rotating cogwheel forming a pulsed light ray that propagates 8 km to a distance mirror and reflected back to the cogwheel. The time to form a single light pulse and the 16 km distance are used to calculate the velocity of light but a single light pulse cannot produce an intensity after propagating the distance of 16 km. Foucault (1850) replaced Fizeau's cogwheel with a rotating mirror but a single light pulse of Foucault's experiment also forms the same intensity problem as Fizeau's experiment. Fabry-Perot (1899) uses a glass wedge interference effect to obtain a wavelength that is used in a wave equation (λf = c) to calculate the velocity of light but the glass wedge interference effect is formed by an ether, composed of matter, that does not physically exist (vacuum). Michelson (1926) attempts to calculate the velocity of light using an interferometer that is employed to form an interference effect which is used to obtain a wavelength that is inserted into a wave equation (λf = c) to calculate the velocity of light but Michelson's interference effect is produced by interfering light waves represented with the wave equation but the interfering light waves are formed by the motion of an ether that does not physically exist.
 May 1st 2018, 07:25 PM #2 Forum Admin     Join Date: Apr 2008 Location: On the dance floor, baby! Posts: 2,554 Light (or any Quantum wave) does not need an ether to propagate. That's the whole point of the results of the MM experiment. -Dan __________________ Do not meddle in the affairs of dragons for you are crunchy and taste good with ketchup. See the forum rules here.
 May 2nd 2018, 12:35 AM #3 Senior Member   Join Date: Apr 2017 Posts: 453 On the subject of eclipses ... It seems extraordinary to me that 'primitive' people three thousand years ago were able to predict solar eclipses !! How on Earth did they do it ... Take the greatest minds from this forum, stick them on a desert island with only basic equipment ... Do you think they could do it????
 May 2nd 2018, 01:29 AM #4 Senior Member     Join Date: Jun 2016 Location: England Posts: 786 Not sure what point LoveBunny is trying to make. Oz, If the marooned forum members and their decedents made it a point of religion to observe and document the behaviour of celestial objects, then yes I believe they would (in time) be able to predict the eclipses. topsquark likes this. __________________ ~\o/~
May 2nd 2018, 04:44 AM   #5

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 Originally Posted by Woody Not sure what point LoveBunny is trying to make.
I don't think he has a point, just arguments to try to denigrate Physics in areas he doesn't understand. Honestly, he seemed to start out alright but he's getting close to being merely another troll who doesn't understand much of what he's talking about.

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 May 3rd 2018, 10:50 AM #6 Banned   Join Date: Apr 2018 Posts: 92 The post indicates that the velocity of light has not been measured properly; therefore, the velocity of light is infinite or could have a magnitude of 23 or 59. Really, I do not understand what I am talking about? So, lets go point for point about the above post to see who understand and who does not. https://www.google.com/search?q=roem...qNX3WpPzCY6FM: To start off here the diagram regarding Roemer calculation of the velocity of light. Do you agree that Roemer calculation is invalid and explain why if not. Last edited by lovebunny; May 3rd 2018 at 10:53 AM.
May 3rd 2018, 11:02 AM   #7

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 Originally Posted by lovebunny The post indicates that the velocity of light has not been measured properly; therefore, the velocity of light is infinite or could have a magnitude of 23 or 59. Really, I do not understand what I am talking about? So, lets go point for point about the above post to see who understand and who does not. https://www.google.com/search?q=roem...qNX3WpPzCY6FM: To start off here the diagram regarding Roemer calculation of the velocity of light. Do you agree that Roemer calculation is invalid and explain why if not.
As it happens, I'm a Physicist. I have actually done an experiment myself and my measurement of c was within something like 5% of the accepted value. I have not actually done the Roemer experiment, but as my result was fairly close to his I don't have any doubts that his method was done correctly.

-Dan
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Last edited by topsquark; May 3rd 2018 at 11:04 AM.

 May 3rd 2018, 12:38 PM #8 Banned   Join Date: Apr 2018 Posts: 92 So lets start at the beginning. Do you agree that the following figure originates from Roemer's calculation of the velocity of light? https://www.google.com/search?q=roem...qNX3WpPzCY6FM: Also, briefly describe, in your own words, how Roemer calculated the velocity of light since you are a physicist that should not be so difficult. Please include the following: A. Do you agree that the figure is Roemer's. B. A short description of Roemer's method. . Last edited by lovebunny; May 3rd 2018 at 12:41 PM.
 May 3rd 2018, 02:37 PM #9 Banned   Join Date: Apr 2018 Posts: 92 This is Roemer's paper but you probably are already looking at it, right? http://zelmanov.ptep-online.com/papers/zj-2008-01.pdf
May 4th 2018, 06:25 AM   #10
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 Originally Posted by lovebunny The post indicates that the velocity of light has not been measured properly; therefore, the velocity of light is infinite or could have a magnitude of 23 or 59.
That's absurd. Even if his measurement was wrong, there is considerable evidence that the speed of light in a vacuum is 299792458 m/s from other studies. If the value was wrong, then lots of technology we have wouldn't work. Considering that they do work, I'd say there is virtually no wiggle room for considering alternative values of the speed of light in a vacuum.

Last edited by benit13; May 4th 2018 at 06:38 AM.

 Tags determination, light, sofar, speed

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