[happy6666 (OP)]

Hi I am a cheerleader a X high school and need to improve my intellectual acumen so that I can become head cheerleader. So please tell me me if this is true and how I can respond to the egg heads so I can be popular.



"It is questionable if the velocity of light can be measured. Roemer is accredited as the first to measure the velocity of light but Io cannot produce four viewable eclipses in the same year. Huygens attempts to measure the velocity of light using the distance of the earth's orbital diameter KL but at the position L, the dark side of the earth (night) is not facing Jupiter. Bradley's stellar aberration is used to calculate the velocity of light but the stars of the stellar universe are stationary (celestial maps). Fizeau measures the velocity of light using a rotating cogwheel but to measure the velocity of light requires the time a single light pulse propagates a specific distance yet Fizeau's experiment is not producing a single independent cogwheel light pulse, and, a single cogwheel light pulse would not form an intensity after propagating the distance of 1 km. Foucault replaced Fizeau's cogwheel with a rotating mirror but Foucault's experiment forms the same single light pulse intensity problem. Weber-Kohlrausch (1856) calculates the velocity of light using the units of a charged capacitor and the current that is produced when the capacitor is discharged but electrons that are propagating in a copper wire at the velocity of 10^6 m/s are being used to determine the velocity of light. 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 the motion of an ether that does not exist (vacuum). Michelson (1926) attempts to calculate the velocity of light using an interferometer but Michelson's interference effect is also formed by an ether, and, the result of Michelson's ether experiment was negative."

[happy6666 (OP)]

Roemer describes the measurement of the velocity of light in his paper "A Presentation Concerning the Propagation of Light Determined" (1676). Roemer calculates the velocity of light using four eclipses of Io that are viewed in the same year. The earth propagates away from Io (a moon of Jupiter) while on the earth's orbital path LK (fig 2) and the earth propagates towards Io while on the orbital path FG where Io produces four eclipses when the earth is at the orbital positions L, K, F and G. The earth's orbital path distances LK and FG are equal and equivalent to the distance of (152,853.5047 s) (40) (30,000 m/s) = 1.831 x 1011 m that correspond with 40 rotations of Io around Jupiter. When the earth is at the position K, the light arriving from Io would propagate a longer distance equal to LK compared to when the earth is at the position G. Roemer observed a 10 minute (600 s) time delay of Io's eclipse, on the evening of November 9, that Roemer attributed to light propagating the extra distance of LK that is used to calculate the velocity of light (1.831 x 1011 m) / (600 s) = 3.05 x 108 m/s but it is not physically possible for Io to form four viewable eclipses in the same year when the earth is at the positions L, K, F, and G. An eight year time interval is used to justify the formation of the four eclipse of Io at, L, K, F and G, that are used to calculate the velocity of light but Jupiter is propagating around the Sun which would require the eclipses of Io to occur in the same year to form the alignment of the earth and Jupiter depicted in Figure 2.

[happy6666 (OP)]

https://commons.wikimedia.org/wiki/File:Illustration_from_1676_article_on_Ole_R%C3%B8mer%27s_measurement_of_the_speed_of_light.jpg [nofollow]

[happy6666 (OP)]

Huygens describes the earth propagating from K to L where the earth aligns with Jupiter and the Sun when the earth is at the orbital position L. Huygens uses the earth's orbital diameter KL and a 22 minute time delay of the eclipse of Io when the earth is at the position L to calculate the velocity of light (2.99 x 1011 m) / (1320 s) = 2.26 x 108 m/s. Huygens' 22 minute time delay of Io's eclipse is produced by light propagating the distance of the earth's orbital diameter KL but at the position L, Huygens cannot view Io since the dark side of the earth (night) is not facing Jupiter. Example, Jupiter is in opposition on May 9, 2018 and on November 24, 2018 after the earth propagates the distance of the earth's orbital diameter and aligns with Jupiter and the Sun (fig 3), in a 6.506 month time period, Jupiter does not appear in the night sky (http://www.seasky.org/astronomy/astronomy-calendar-2018.html [nofollow].). The extra time of .506 month (15 days) is added to the six month time interval to align the earth with Jupiter and the Sun since Jupiter is in motion around the Sun when the earth propagates from K to L.

[happy6666 (OP)]

https://www.alamy.com/stock-photo-illustration-of-roemers-determination-of-the-speed-of-light-in-1676-104003348.html [nofollow]

[happy6666 (OP)]

Lookie Roemo and Huygens use different figures. I think they have different girl friends since everyone has a different figure.

[alancalverd]

All drivel.

Michelson & Morley measured the speed of light in two directions and found it was identical, hence there is no requirement for or evidence of  an aether.

Maxwell calculated the speed of a selfpropagating electromagnetic wave in terms of electrostatic and magnetostatic properties which can be measured independently in a laboratory (I've done it, as did most undergraduate physics students of my generation). and does not require an aether.

A later group of undergraduates that I had the honour of teaching, used a variant of the Michleson-Morley technique (a spinning mirror) to get an answer very close to the one in the textbook.

Every reaction involving a mass-energy exchange shows that E = mc^2    with the same value of c.

If you are incapable of seeing a light at 1 km distance (a) you shouldn't be driving at night and (b) you probably died before the invention of the laser - or even a lens. Never mind astronomy.

Today I flew around 200 miles using radar and radio ranging for navigation. Both depend on a precise knowledge of the speed of light, and I arrived exactly as intended, helped somewhat by a GPS system that relies on a precise knowledge of the speed of light.

The best way to progress in science is to start from where you are, using the knowledge you have. In the case of physics, the classic experiments have been reproduced so often that you can take the numbers in the textbook as true. Chemistry doesn't always work as well in practice as it does on paper. Biology is a lot more complicated, and psychology just adds mystery to biology, but it takes a fool or a genius to find a flaw in textbook physics, and there aren't many geniuses around.   

[happy6666 (OP)]

Egg head said to ask you "Is MMX using an interferometer?"

[Bored chemist]

"Can the velocity of light be calculated "
Yes.
https://en.wikipedia.org/wiki/Maxwell%27s_equations#Vacuum_equations,_electromagnetic_waves_and_speed_of_light

Egg head said to ask you "Is MMX using an interferometer?"

Also, yes.

[happy6666 (OP)]

Does the interferometer involve an interference effect? Also, it should be can the velocity of light be measured?


"It is questionable if the velocity of light can be measured."

[Kryptid]

This is a bizarre question. Light can be emitted and detected. The difference in the timing between those events can be measured. Divide the distance by the time taken and you have the speed.

[happy6666 (OP)]

How fast do electrons in a circuit propagate? (Hint: 10^-6 m/s). How can you measure the velocity of light if the electrons of a circuit that you are using to measure the velocity of light is propagating less than the velocity of light. By the time you detect the velocity of light the light pulse has already past. You are not measuring the velocity of light you are measuring the speed of the circuit.

[Kryptid]

How fast do electrons in a circuit propagate? (Hint: 10^-6 m/s).

Sounds like you are referring to drift velocity, not the speed of an actual signal.

How can you measure the velocity of light if the electrons of a circuit that you are using to measure the velocity of light is propagating less than the velocity of light. By the time you detect the velocity of light the light pulse has already past. You are not measuring the velocity of light you are measuring the speed of the circuit.

Except that isn't what is happening at all. You aren't "detecting the velocity of light". All you are doing is measuring times. When was the light emitted? What was it detected? What is the distance between the emitter and detector? The rest is just down to math.

[alancalverd]

Interference does not require the existence of an aether. Which is just as well because we can observe interference and not the effect of an aether.

Your eggheads seem to be addled.

You can't read this because the drift velocity of electrons won't allow my computer to work fast enough.

[Hayseed]

Sounds real simple.  Just one problem, when do you start the velocity clock?  At what time does the emission occur, when do you start the timer?  We need the exact start time.

Anything that we use for detecting, (current) moves slower the c. That will need to be accounted for.

Without knowing the emission time, and the emission duration, no meaningful measurement may be taken.  Measuring just a section of flight path.......does not relate relative velocity.

And any reflection, or altered path.........will reset c from that point.

How can we set an experiment up?

[happy6666 (OP)]

There is also the problem of how do you form a single independent light pulse?

[Hayseed]

I think, that I can emit one photon from an antenna.  But I am old and decrepit now.  Any experimenters out there?

[Kryptid]

Just one problem, when do you start the velocity clock?  At what time does the emission occur, when do you start the timer?  We need the exact start time.

You don't need to know the exact start time to get a rough estimate. It all depends on what error tolerance you want.

Anything that we use for detecting, (current) moves slower the c. That will need to be accounted for.

If the current travels at the same speed in both the emitter and detector, that problem will mostly take care of itself (if the emitter and detector have similar lengths of wiring, that is). A delay in the emission will be roughly equal to the delay in detection, giving you the same time estimate as if there was no delay at all.

 

Without knowing the emission time, and the emission duration, no meaningful measurement may be taken.  Measuring just a section of flight path.......does not relate relative velocity.

Sure you can. If pushing a button simultaneously stops an electronic clock and causes a light bulb to be turned on, you have the rough time that the light was turned on. There will obviously be some error based on how long it took the current to heat the filament to incandescence, but that factor becomes decreasingly important the larger the distance between emitter and detector.

Alternatively, we can adjust the set-up to use two identical detectors that are inline with each other. The time that the light was turned on is now unimportant. The first detector will register a particular detection time and the second one will register a different time. Check the difference between the detection times to tell how long it took the light to travel from detector 1 to detector 2. Then divide that by the elapsed time. Since both detectors are identical, any delay due to the circuit is also identical and therefore cancels out.

There is also the problem of how do you form a single independent light pulse?

You wouldn't have to. The time that the detector went from no detection to a detection is all you are looking for. It's okay to keep the bulb on.

[Hayseed]

So, you believe that emission starts when you push a bottom?

And are you assuming that emission duration is equal to absorption duration?

[happy6666 (OP)]

Are you detecting the beginning or the end of the light pulse? And how long is the light pulse that is used to measure the velocity of light. Do you have a name for this experiment. Is it a derivative of the Newton lantern experiment?