Thread: The Faulty Michelson-Morley Experiment

For all of you that don't know, the attached image is of the Michelson-Morley interferometer (which I'll call the MM device from now on). The purpose of the MM device was to detect the aether (light's medium). The idea was that if the Earth orbits the Sun at 30km/s, and that if the aether was stationary relative to the Sun, then the change in speed of light on the surface of the Earth due to the Earth's motion through the aether should be at least 30km/s.

How the device worked was that a beam of light from a light source was directed toward a semi-silvered mirror. The semi-silvered mirror would split the beam into two perpendicular beams (blue and green in the image), and each one of these beams would bounce off of a mirror. The reflected beams would would recombine at the semi-silvered mirror, and finally the recombined beams would be observed. The idea is that if the MM device is moving through the aether, then one of the two split beams would take longer to reach their mirror and return to the semi-silvered mirror. This delay between the two beams would cause a phase shift between the two beams which could be seen as interference patterns in the final combined beam. The MM device was made so that it could be rotated, so that any change in the speed of light in any direction can be observed.

As it turns out, the MM device detected a very small change in the speed of light (much smaller than the 30km/s expected), and since this small change was within the margin of error, it was assumed that the omnidirectional speed of light on the surface of the Earth was constant (it is equal to c in all directions). Over the years, this same experiment was done with higher accuracy, and the change in the speed of light measured remained much smaller than 30 km/s.

Due partly to this experiment, Einstein concluded that not only is the speed of light constant for an observer on the surface of the Earth, but that the speed of light is constant for all inertial observers.

Now, let me tell you why the MM device, and all similar experiments, were faulty. The MM device did not take into consideration the frequency shift of the beams of light in the device that would have resulted from a change in the speed of light. You see, if light slowed down between any two mirrors in the device, the light would take longer to travel between the two mirrors. The frequency of the light would decrease (red-shift) by the same amount, relative to the MM device, so the sum of the wavelengths of the light between the two mirrors would not change.

Sum of wavelengths of light between mirrors = frequency (relative) * time (relative)

If the speed of the light between any two mirrors in the device increased, it would take less time for the light to travel between those two mirrors. The frequency of the light, relative to the MM device, would increase (blue-shift) by the same amount, causing the sum of the wavelengths between the mirrors to remain constant, as well.

Since the sum of the wavelengths would remain constant between any two mirrors in the MM device regardless of the speed of the light, when the beams are recombined they would not be out of phase even if the speed of light between any of the mirrors has changed. So, as a result, interference patterns would not be seen even if the speed of light did change in the MM device.

In conclusion, the MM device, and similar devices, CAN NOT measure any change in the speed of light. All of the data collected from these devices should be discarded, and any theory resulting from them should be questioned.

The MM interferometer does not measure the redshift but a phase shift of a coherent wave. The redshift is a measure of the relative radial velocity of the light source or the detector, while the phase shift should be a measure of the assumed change of light speed relative to the experimental set-up. The light source does not move relative to the detector. So, there is no redshift.

The effect of a changing light speed on the result of the experiment can be easily shown, when a gas cell is introduced in one arm of the interferometer. Both directions of the light path penetrate this gas cell. The light speed is altered in a different medium of a certain gas pressure, and you can see the diffraction pattern changing depending on the pressure inside the cell. This is a standard experiment on undergraduate level to derive the refractive index of a certain gas.

http://www.stkate.edu/physics/phys11...michelson.html

The impact of an assumed external velocity field does not compensate, because in your drawing, the light path in one direction is twice as long as in the other direction. You have to add the path between light source and beam splitter as well as the path between the beam splitter and the detector of course. These paths produce a net effect that should be able to show any influence of the direction of the light.

Dishmaster,

The MM interferometer does not measure the redshift but a phase shift of a coherent wave. The redshift is a measure of the relative radial velocity of the light source or the detector, while the phase shift should be a measure of the assumed change of light speed relative to the experimental set-up. The light source does not move relative to the detector. So, there is no redshift.

If you change the speed of any wave relative to an observer its frequency will change relative to that observer. We witness this all the time with sound. There is no reason why an electromagnetic wave would be any different.

Take a piece of paper and draw a wave on it with the length of five wavelengths. Now move slowly relative to that paper. Now speed up. Did you notice that not only did the wave pass by faster when you speed up, but its frequency increased also (all five wavelengths passed by faster).

Dishmaster,

The impact of an assumed external velocity field does not compensate, because in your drawing, the light path in one direction is twice as long as in the other direction. You have to add the path between light source and beam splitter as well as the path between the beam splitter and the detector of course. These paths produce a net effect that should be able to show any influence of the direction of the light.

I'm stating that the number of wavelengths of light between any section of the MM device remains constant regardless of the speed of light between any two points. This would mean that the MM device detects nothing.

Originally Posted by Prosoothus

If you change the speed of any wave relative to an observer its frequency will change relative to that observer. We witness this all the time with sound. There is no reason why an electromagnetic wave would be any different.

True, but if you move just as fast as the source of the sound and in the same direction, you do not hear a difference. The same holds for the MM experiment, where the light source and the detector do not move relative to each other.

Prosoothus

IMO, I concluded that the MM experiment prooved that the ether (space) was not the carrier of light.
So why was there no difference?
Well, my opinion is that the 'source' of the light was moving with the experiment.
So the velocity of light is fixed to the source since the carrier is the electric fields that surround the sources rather than a separate carrier as an ether.

Cosmo

Dishmaster,

True, but if you move just as fast as the source of the sound and in the same direction, you do not hear a difference. The same holds for the MM experiment, where the light source and the detector do not move relative to each other.

Let me try to dissect the functions of the MM device in order to try to simplify my assertions.

First, you have to remember that the MM device does not measure speed directly. It measures the phase difference between the two perpendicular beams of light in the device (shown as blue and green in the image). The phase difference is assumed to be caused by two things in the device: the physical lengths between the semi-silvered mirror and the other two mirrors, and the speed of light.

If the round-trip distance that light has to travel from the semi-silvered mirror to mirror 1 is larger than the round-trip distance that light has to travel from the semi-silvered mirror to mirror 2, then the number of wavelengths of light in the round-trip to mirror 1 is larger than the number of wavelengths of light in the round-trip to mirror 2. If the difference between the number of wavelengths of light in the round-trip to mirror 1 and to mirror 2 is not a whole number, then there will be some destructive interference. This part I agree with.

The second assumption is that if light travels faster or slower to one of the mirrors and back, that the number of wavelengths of light in that section will be smaller or larger. This assumption is not true. I'm stating that the number of wavelengths of light between any two points remains constant regardless of the speed of the light between those two points. I have a perfect GIF file on my computer illustrating my point, but there's no way to show that animation on thescienceforum.com. So, let me try to explain it:

The animation shows a wave with the length of about 10 wavelengths. Superimposed on the wave is a box that is moving at a constant speed. If you look at the part of the wave inside the box, it is equal to two wavelengths. The illustration shows that regardless of how fast the box is moving, or the wave is moving relative to the box, there will always be two wavelengths of the wave inside the box.

Now if you take the above example, replace the wave with an electromagnetic wave, replace the box with two mirrors (the right and left side of the box), and move the wave instead of moving the box, you'll find that no matter how fast the electromagnetic wave is traveling, the number of wavelengths between the two mirrors remains constant (equal to 2). If you apply this knowledge to the MM device, you'll find that the sum of the wavelengths of light in any trip that light may take through the device remains constant regardless of the speed of the light. In other words, if there are 100 wavelengths of light in the round-trip of light between the semi-silver mirror and mirror 1 when light is traveling at c, there will be 100 wavelengths of light in the round-trip of light between the semi-silver mirror and mirror 1 if the light is moving at 1/2c. Since this same fact applies to the distance between any two points in the MM device, the sum of the wavelengths of light that both beams take through the device will remain the same regardless of the speed of that light. As a result, when the two beams are re-joined, the interference pattern observed is independent of the speed of light of those beams. In other words, the speed of light is superfluous to the resulting interference pattern in the MM device.

Cosmo,

IMO, I concluded that the MM experiment prooved that the ether (space) was not the carrier of light.
So why was there no difference?

I thought for years that the MM experiment actually measured the speed of light only to find out that it doesn't. The resulting interference patterns in the experiment are dependent on only two things, the length that light has to travel in the device, and the frequency of the light. The speed of the light in the device has no effect on the interference patterns. Check out the post I just posted before this one. It explains in detail why this is the case.

Originally Posted by Prosoothus

I thought for years that the MM experiment actually measured the speed of light only to find out that it doesn't. The resulting interference patterns in the experiment are dependent on only two things, the length that light has to travel in the device, and the frequency of the light. The speed of the light in the device has no effect on the interference patterns. Check out the post I just posted before this one. It explains in detail why this is the case.

I did not see any other post by you on this subject matter.

My conclusion was based on the movement of light in 'both' directions simultaneously to determine the relativity to the Earths motion.
None was detected.
So this ruled out the idea of an ether as a carrier.

The speed of light generally uses a revolving mirror to determine its velocity?

Cosmo

Cosmo,

My conclusion was based on the movement of light in 'both' directions simultaneously to determine the relativity to the Earths motion.
None was detected.
So this ruled out the idea of an ether as a carrier.

I'm kind of confused. Which experiment are you referring to? The MM experiment tried to measure the difference between two beams of light that are traveling perpendicular to each other.

The reason I say "tried" is because the MM device does not directly measure the speed of light, it measures the phase shift between two wave forms. And as I showed earlier in this thread, the speed of light has no effect on the wave forms in the MM device, so the MM device cannot measure the speed of light.

I agree with Dishmaster. If the transmitter and receiver are fixed, the frequency cannot change. Frequency is the number of beats or pulses per unit time, and every beat or pulse transmitted must also be received.

If my friend mails me a letter a day, I will receive a letter a day, whether it arrives by air mail or pony express. The letters en route by pony express will be closer together (shorter wavelength).

The MM experiment attempted to detect a phase shift as the result of two unequal path lengths. The result was null. The conclusion, the ether did not affect the speed of light and was thus redundant. It did not eliminate the ether.
The problem was using the frame of the moving observer for the lab frame, which had no relative motion, i.e. the length in the direction of motion is calculated too long.

Originally Posted by phyti

The MM experiment attempted to detect a phase shift as the result of two unequal path lengths. The result was null. The conclusion, the ether did not affect the speed of light and was thus redundant. It did not eliminate the ether.
The problem was using the frame of the moving observer for the lab frame, which had no relative motion, i.e. the length in the direction of motion is calculated too long.

You have two choices. You can eliminate the aether (which is different from the organic family of ethers) or you can keep the aether and institute the Lorentz transformation by fiat. The former is the simpler formulation.

Harold14370,

agree with Dishmaster. If the transmitter and receiver are fixed, the frequency cannot change. Frequency is the number of beats or pulses per unit time, and every beat or pulse transmitted must also be received.

Every time the speed of a wave changes relative to an observer, the frequency of that wave will change relative to the observer as well.

Maybe I complicated the way I stated what I was thinking. Let me try to simplify it using an analogy.

Let's say you have a audio speaker that's stationary on the Earth. You turn on the speaker, and it produces a sound of a specific tone (frequency). Now, you're one hundred meters away and you hear the speaker. Since you are stationary relative to the Earth's atmosphere (the medium of sound), the frequency of the sound will be equal to the same frequency as the speaker produced.

Now, let's say that you start moving towards the speaker at a specific speed. Because of this, the speed of the sound wave will speed up relative to you, and the frequency of the sound wave will increase. The frequency of the sound increased because the speed of the wave increased. But let's forget about the frequency shift of the sound for a second. It's kind of irrelevant to the point I'm trying to make.

As state above, let's say that there's a speaker making a sound of a certain frequency and you're moving towards it at a certain speed. Now, lets say you pulled out a ruler that's one meter long and you hold it out in front of you so that it's pointing towards the speaker. For the sake of argument, let's say that you have "audio vision" so that you can actually see the sound, and let's say that you have a very quick mind. When you're traveling towards the speaker, you look at your ruler and count how many wavelengths of the sound fit on the length of your one meter ruler. You find that there are N number of wavelengths of sound across your one meter ruler.

Now, you decide to speed up towards the speaker and count the number of wavelengths of sound on your one meter ruler again. You find that the count did not change, there are still N wavelengths of sound there. Next, you decide to stop, and start moving in the opposite direction of the sound. You look down at your ruler to find out that there are still N wavelengths of sound on your ruler. You conclude that regardless of the speed that you are moving relative to the sound, the number of wavelengths of sound on your ruler remained constant even though the frequency and speed of the sound, relative to you, has changed.

You're surprised at the results at first, but when you think about it, it makes sense. You see, if the frequency of the speaker is constant, then the wavelength of the sound is constant. And if the length of your ruler is constant (1 meter), and the length of of wavelength of the sound is constant, then the total number of wavelengths of that sound on your ruler must be constant as well.

Now, lets take the same example I gave above and replace the sound with light, the Earth's atmosphere with light's medium, and the ruler with two mirrors (a semi-silver mirror on one end, and a full mirror on the other). As in the example above, you'll find that no matter how fast you're moving towards, or away from, the light, the number of wavelengths of light between the two mirrors will remain constant. Actually, the number of wavelengths of light between any two points remains constant regardless of how fast those points are moving relative to the light (as long as the distance between the points remain constant).

Now, let's apply what I stated above to the MM device. In the MM device there are two beams that take different paths through the device. The first beam takes this path:

d1 - Light source to semi-silver mirror
d2 - Semi-silver mirror to mirror 1
d3 - Mirror 1 to semi-silver mirror
d4 - Semi-silver mirror to light detector

The second beam takes this path:

d5 - Light source to semi-silver mirror.
d6 - Semi-silver mirror to mirror 2
d7 - Mirror 2 to semi-silver mirror
d8 - Semi-silver mirror to light detector

Now, let's assume that the MM device is stationary relative to light's medium. In this case the total number of wavelengths of light in the entire path of the first beam of light is equal to:

N1 = n1+n2+n3+n4 (where n1 to n4 is the number of wavelengths of light in the distances d1 to d4)

And the total number of wavelengths of light in the entire path of the second beam of light is:

N2 = n5+n6+n7+n8 (where n5 to n8 is the number of wavelengths of light in the distances d5 to d8 )

The MM device compares N1 to N2 (N1-N2) to measure the speed of light. There has to be a fractional difference between N1 and N2 in order for any destructive interference to occur. There is only one problem, even if the speed of light changed in the device, then n1,n2,n3,4,n5,n6,n7, and n8 would remain constant for the reason I stated earlier in my post. And if all of those remained constant, then N1 and N2 will remain constant as well. And since the MM device measures the difference between N1 and N2, and N1 and N2 remain constant regardless of the speed of light, the MM device would not be able to measure a change in the speed of light at all.

Suppose there is a fleet of red cars and a fleet of green cars. Every minute, a red car leaves the garage, travels east at 60 mph for 60 miles, and returns at 60 mph. At any moment in time there are 60 cars on the eastbound road, 1 mile apart and 60 cars westbound, 1 mile apart. The round trip takes 2 hours.

Every time a green car leaves the garage headed east, a red car heads north 60 miles at 80 mph, returning south at 40 mph. The northbound leg of the journey takes 60/80 of an hour, or 45 minutes. The southbound leg takes 60/40 of an hour or 90 minutes. Total round trip 90+45=135 minutes. So the red and green cars do not arrive back at the same time; they are 15 minutes apart. The space between northbound cars is 80/60 miles = 4/3 miles. The number of cars on the northbound lane is 60/(4/3)=45. The space between southbound cars is 40/60=2/3 mile. The number of cars on the southbound lane is 60/(2/3)=90. At any given time, there are 135 cars heading north-south, as compared to 120 heading east-west.

The number of cars on the road is analogous to your sum of the number of wavelengths, and your analysis is not correct.

my solution : because the simetrik in time for the QM its stabilise on the future arivel of the bim otherwise the speed wasnt constant , if you move the device manually you feel it ; if the Earth move you dont feel it , how ?

Harold14370,

Let me point out your error:

The northbound leg of the journey takes 60/80 of an hour, or 45 minutes.

This statement is true.

The space between northbound cars is 80/60 miles = 4/3 miles.

This statement is also true.

If the distance between the cars has increased, and the speed of the cars have increased by the same amount, won't the number of cars that traverse the road at any given time remain constant?

60/80 * 80/60 = 1

If you apply this to the MM device, you'll find that the number of wavelengths of light hitting a mirror per unit of time will remain constant regardless of the speed of the light.

Let me try to simplify this even further:

You have a ruler equal to one meter. You also have a wave with a wavelength of 0.1 meters. How many wavelengths of that wave can fit in your ruler?

total wavelengths = distance/length of one wavelength

total wavelengths = 1/0.1

total wavelengths = 10

So 10 wavelengths of the wave can fit in the one meter ruler.

Now, let's say that you start moving the ruler relative to the wave. How many wavelengths of the wave can now fit in the ruler? The same as before, 10. Why? Look at the equation that I provided above. Notice that there is no speed factor in the equation. Speed is superfluous to the result of the equation. If the length of the wavelength remains constant, and the length of your ruler remains constant, the number of wavelengths that fit on your ruler will remain constant.

If you apply this equation to any two points in the MM device, you'll find that the speed of light between those points does not effect the number of wavelengths of light between those points. So in other words, the total number of wavelengths of both beams of light through the MM device remain constant regardless of the speed of light in any one section. Since the results of the MM device are obtained by comparing the sum of the wavelengths of those two beams of light, the results of the experiment are independent of the speed of light in the device.

Originally Posted by Prosoothus

Harold14370,

Let me point out your error:

The northbound leg of the journey takes 60/80 of an hour, or 45 minutes.

This statement is true.

The space between northbound cars is 80/60 miles = 4/3 miles.

This statement is also true.

If the distance between the cars has increased, and the speed of the cars have increased by the same amount, won't the number of cars that traverse the road at any given time remain constant?

60/80 * 80/60 = 1

If you apply this to the MM device, you'll find that the number of wavelengths of light hitting a mirror per unit of time will remain constant regardless of the speed of the light.

the distance dont increased or decreased, the total speed spouse to change and affect the lasting time but it dont

We measure the forward distance, sending a light signal from A (event 1) to the front end where it's reflected (event 2) back to A (event 3). A is coincident with events 1 and 3, but measures event 2 indirectly using his clock. He assumes he is at rest, therefore divides his indicated time (3') by 2 and multiplies by c, resulting in event 2'. A vertical line from 2' to the x axis shows his calculated distance is greater than the physical distance d.
Let g = gamma and t = the time for light to travel both ways (2d) along a rod at rest. Mathematically, for a moving rod, the radial axis (y or z) requires gt and the x axis requires ggt. For A gt becomes t, and ggt becomes gt, adjusting for time dilation.
The x time still includes compensation for motion of the frame, but a true rest frame would not require this.
SR theory is built on ideal symmetry and a constant light speed, therefore an x coordinate transformation is required (1/gamma) to reduce A's calculated length to d.
Notice SR transforms the calculated length, not the actual length.
In summary, the observer who chooses to consider his moving frame at rest, will reassign the time of the forward remote event as earlier on his clock (later for backward events). This explains his skewed spatial axis of simultaneity. In the process of constructing a pseudo rest frame, time dilation only removes some of the extra time due to light compensating for the motion of the moving frame. SR provides the transformation that makes it work.
If A chooses to accept his motion, then knowing SR he adjusts his time with the inverse g function and agrees with the description by U.

drawing

Originally Posted by Prosoothus

Harold14370,

agree with Dishmaster. If the transmitter and receiver are fixed, the frequency cannot change. Frequency is the number of beats or pulses per unit time, and every beat or pulse transmitted must also be received.

Every time the speed of a wave changes relative to an observer, the frequency of that wave will change relative to the observer as well.

Maybe I complicated the way I stated what I was thinking. Let me try to simplify it using an analogy.

Let's say you have a audio speaker that's stationary on the Earth. You turn on the speaker, and it produces a sound of a specific tone (frequency). Now, you're one hundred meters away and you hear the speaker. Since you are stationary relative to the Earth's atmosphere (the medium of sound), the frequency of the sound will be equal to the same frequency as the speaker produced.

Now, let's say that you start moving towards the speaker at a specific speed. Because of this, the speed of the sound wave will speed up relative to you, and the frequency of the sound wave will increase. The frequency of the sound increased because the speed of the wave increased. But let's forget about the frequency shift of the sound for a second. It's kind of irrelevant to the point I'm trying to make.

As state above, let's say that there's a speaker making a sound of a certain frequency and you're moving towards it at a certain speed. Now, lets say you pulled out a ruler that's one meter long and you hold it out in front of you so that it's pointing towards the speaker. For the sake of argument, let's say that you have "audio vision" so that you can actually see the sound, and let's say that you have a very quick mind. When you're traveling towards the speaker, you look at your ruler and count how many wavelengths of the sound fit on the length of your one meter ruler. You find that there are N number of wavelengths of sound across your one meter ruler.

Now, you decide to speed up towards the speaker and count the number of wavelengths of sound on your one meter ruler again. You find that the count did not change, there are still N wavelengths of sound there. Next, you decide to stop, and start moving in the opposite direction of the sound. You look down at your ruler to find out that there are still N wavelengths of sound on your ruler. You conclude that regardless of the speed that you are moving relative to the sound, the number of wavelengths of sound on your ruler remained constant even though the frequency and speed of the sound, relative to you, has changed.

You're surprised at the results at first, but when you think about it, it makes sense. You see, if the frequency of the speaker is constant, then the wavelength of the sound is constant. And if the length of your ruler is constant (1 meter), and the length of of wavelength of the sound is constant, then the total number of wavelengths of that sound on your ruler must be constant as well.

Now, lets take the same example I gave above and replace the sound with light, the Earth's atmosphere with light's medium, and the ruler with two mirrors (a semi-silver mirror on one end, and a full mirror on the other). As in the example above, you'll find that no matter how fast you're moving towards, or away from, the light, the number of wavelengths of light between the two mirrors will remain constant. Actually, the number of wavelengths of light between any two points remains constant regardless of how fast those points are moving relative to the light (as long as the distance between the points remain constant).

The failing of your example is that you only are considering movement of the observer with respect to the medium and not movement of the source with respect to the medium.

If it is the speaker that is moving towards you relative to the the air, the wavelength is shortened and it is lengthened by the speaker moving away.

Consider a 100hz sound and a movement of 1m/sec. At t0 the front of the wave leaves the speaker traveling at 340m/s relative to the air. This means that it travels at 339 m/s relative to the speaker. In other words, 1/100 of a sec later when the rear of the wave leaves the speaker, the front of the wave has traveled 3.39 m relative to the car, and thus has a wavelength of 3.39m.

If the speaker is moving away, then the wave travels at 341 m/s relative to the speaker, for a distance of 3.41 m after 1/100 sec, and a wavelength of 3.41 m.

Now, the M&M experiment involves both a moving mirrors and a moving source.

An example using cars would work like this:

You have a semi driving down the road towing two cars. The semi is traveling at 36 kph down the road (the road represents the aether) The semi releases one car which immediately travels at 72 kph down the road in the opposite direction as the semi. The relative velocity between semi and car is now 108 kph. 1 sec later it releases the second car which the first at 72 kph, the cars are 30 meters apart.

Following 10 km behind the first semi is a second semi. The first car reaches it after 333.33 sec, turns around and immediately heads back towards the first semi at 72 kph(36 kph relative to the semis), 1 sec later the second car reaches the semi and turns around. Since the first car has traveled 10 meters relative to the semi at this time, the distance between the cars is now 10 meters. 1000 secs later the first car returns to the first semi with the second car 10 meters and 1 sec behind. Total trip time, 1,333 sec.

If you want, you can imagine a whole fleet of cars following each other 1 sec apart from semi to semi. If the gap between each car is a wavelength, then 333.33 waves fit one way and 1000 fit another. total wavelengths: 1333.33


Now do the same situation with the semis sitting stationary on the road.
Car 1 leaves driving at 72 kph and 1 sec later, car 2 leaves 20 m behind.
Car 1 reaches semi 2 after 500 sec. Car 2 arrives 1 sec later and after turn around is still 20 m behind. After another 500 sec, car 1 returns to semi 1 with car 2 1 sec and 20 m behind.

With a fleet of cars 500 waves fit on way and 500 the other. total wavelengths: 1000

So, yes, there will be a phase difference in the M&M experiment if there was an aether and the apparatus moved relative to it.

Your second failing is one of hubris.

Look, basically your position is that not only did M&M make the kind of mistake that, if true, would have been embarrassing to a grad student, but that everyone who has done or examined this experiment since has made that same embarrassing error. This is compounded by the fact that the experiment produced results that were contrary to those expected.

This less likely than my taking a non-starting car to 1000 separate mechanics without one of them checking to see if it had a spark. But you would have people accept that it is more likely than your being mistaken.

Janus,

Look, basically your position is that not only did M&M make the kind of mistake that, if true, would have been embarrassing to a grad student, but that everyone who has done or examined this experiment since has made that same embarrassing error.

I agree with your statement.

OK, let's simplify everything. Let's forget about the number of cars on a road, or the distance between them. I will give to a very simple thought experiment, and you can point out exactly where I'm wrong.

You have two points, x1 and x2. The distance between x1 and x2 is exactly 1 meter. You shine a laser, with a wavelength of exactly 694nm, so that the laser light goes through points x1 and x2. For the sake of argument, light has a medium (aether), and there is no such thing as time dilation and length contraction. Exactly how many wavelengths of laser light are between points x1 and x2 in the following four scenarios:

1) The laser is stationary relative to the aether, and points x1 and x2 are stationary relative to the aether.

2) The laser is stationary relative to the aether, but points x1 and x2 are moving away from the laser at the speed of v1.

3) The laser is moving towards points x1 and x2 at the speed of v1, and points x1 and x2 are stationary relative to the aether.

4) The laser is moving towards the direction of points x1 and x2, and relative to the aether, at the speed of v1, and points x1 and x2 are moving away from the laser, and relative to the aether, at a speed of v2.

Here is what I believe:

In case 1 and 2, the number of wavelengths of laser light between points x1 and x2 is:

wavelengths = 1m/694nm

In case 3 and 4, the number of wavelengths of laser light between points x1 and x2 is also:

wavelengths = 1m/694nm (may change)

But in case 3 and 4, the laser light may have changed it's frequency and wavelength because the laser was moving relative to the aether. But in the MM device this change in frequency and wavelength wouldn't matter because the same change would apply to both beams of light in the MM device. In other words, the speed of the light source relative to the aether in the MM device is irrelevant because a light source moving through the aether can simply be looked as a light source of a different frequency that is stationary in the aether.

If you find any of my conclusions incorrect, please indicate what you believe would be the total number of wavelengths between points x1 and x2 in the four scenarios listed above.

Originally Posted by Prosoothus

But in case 3 and 4, the laser light may have changed it's frequency and wavelength because it was moving relative to the aether.

I thought the aether was the medium, so how does the light move any differently relative to the aether?

Harold14370,

I thought the aether was the medium, so how does the light move any differently relative to the aether?

I meant to say that the laser was moving relative to the aether, not the laser light. I will correct my post....

Originally Posted by Prosoothus

Janus,


OK, let's simplify everything. Let's forget about the number of cars on a road, or the distance between them. I will give to a very simple thought experiment, and you can point out exactly where I'm wrong.

You have two points, x1 and x2. The distance between x1 and x2 is exactly 1 meter. You shine a laser, with a wavelength of exactly 694nm, so that the laser light goes through points x1 and x2. For the sake of argument, light has a medium (aether), and there is no such thing as time dilation and length contraction. Exactly how many wavelengths of laser light are between points x1 and x2 in the following four scenarios:

1) The laser is stationary relative to the aether, and points x1 and x2 are stationary relative to the aether.

2) The laser is stationary relative to the aether, but points x1 and x2 are moving away from the laser at the speed of v1.

3) The laser is moving towards points x1 and x2 at the speed of v1, and points x1 and x2 are stationary relative to the aether.

4) The laser is moving towards the direction of points x1 and x2, and relative to the aether, at the speed of v1, and points x1 and x2 are moving away from the laser, and relative to the aether, at a speed of v2.

Here is what I believe:

In case 1 and 2, the number of wavelengths of laser light between points x1 and x2 is:

wavelengths = 1m/694nm

In case 3 and 4, the number of wavelengths of laser light between points x1 and x2 is also:

wavelengths = 1m/694nm (may change)

But in case 3 and 4, the laser light may have changed it's frequency and wavelength because the laser was moving relative to the aether. But in the MM device this change in frequency and wavelength wouldn't matter because the same change would apply to both beams of light in the MM device. In other words, the speed of the light source relative to the aether in the MM device is irrelevant because a light source moving through the aether can simply be looked as a light source of a different frequency that is stationary in the aether.

No, it can't. In the MM device, while moving through the aether, more waves would fit going one way than the other. (it is no different than the car exmaple I gave, just replace the road with the Aether, the speed the cars travel with respect to the road with c and the distance between cars with the wavelength of the light.

If you find any of my conclusions incorrect, please indicate what you believe would be the total number of wavelengths between points x1 and x2 in the four scenarios listed above.

In scenarios 3 and 4 the number of wavelengths between x1 and x2 would be



Here is a simple animation showing the legs of the MM device where the light travels perpendicular to each other. With the horizontal legs, the light is aided or retarded by the "aether wind",(the background represents the Aether) which has an effect on the round trip time. With the vertical legs there is no such aide or retardation affecting the round trip time. (they would drift to the left with the aether, but this does not have any effect on the light's vertical speed wrt the device or its round trip time. I did not add the drift because I wanted to highlight the phase difference after the round trip.)

The two dots represent the leading edges of successive waves of light. each dot leaves the origin moving at a fixed speed relative to the background, and the successive dots of each leg leave a the same time. Each dot travels to the mirror, then reflects back to the origin traveling at the same fixed speed relative to the background.

Note that the horizontal dots arrive back at the origin out of phase to the vertical dots.



Despite what you believe, the MM device was perfectly capable of detecting a ether drift if it existed.

Originally Posted by Janus

Despite what you believe, the MM device was perfectly capable of detecting a ether drift if it existed.

No, it wasnt, because of one thing - absolute length contraction. Heres an extremely simple example. If the MM apparatus was moving at .866c relative to the aether, it would contract to half its length in the direction of its motion. So now, the light light moving forwards and backwards on the contraction axis has a shorter path than the light on the transverse axis, so now both light beams arrive back at the interfereomemter at the same time. Thus the concept of relativity is perfectly compatable with the existence of the aether. The aether shall live on.

I've got to ask, but what does the aether do in such a universe? What does it do, measureably?

the light gose back and forward time , and it is own eather and stabilize on light speed . thanks

Janus,

In the MM device, while moving through the aether, more waves would fit going one way than the other.

You are incorrect, and let me explain to you, in detail, why. This time I will use frequency in my explanation.

You have two points in space, x1 and x2, that are separated my a distance of exactly one meter. You have an electromagnetic wave moving through the aether, and that wave goes through points x1 and x2. The speed of the wave is c relative to the aether, and its frequency is 3 x 10^8 Hz relative to the aether. If you do the calculations you'll find that the wavelength of the wave is exactly 1 meter (relative to the aether).

Case 1 - x1 and x2 are stationary relative to the aether.

In case 1, the wave travels at the speed of c through points x1 and x2. Since x1 and x2 are stationary relative to the aether, the points see the wave speed by at c. To calculate the number of wavelengths of light between x1 and x2 we use this formula:

Number of wavelengths = Distance/(Speed of wave/Frequency of wave)

Where Distance is the distance between points x1 and x2.

I'm sure everyone agrees with this.

Case 2 - x1 and x2 are moving in the same direction as the wave at a speed of 1/2 c.

In this case, the wave is only traveling at 1/2 c relative to points x1 and x2. To calculate the number of wavelengths of light between points x1 and x2 you again use this formula:

Number of wavelengths = Distance/(Speed of wave/Frequency of wave)

So if the speed of the wave decreased by half, then the number of wavelengths between x1 and x2 has doubled, right? WRONG!!!!

This is the mistake that you, and others, are making. The number of wavelengths between x1 and x2 in case 2 is identical to the number of wavelengths between points x1 and x2 in case 1. Now let me explain why:

In case 2, the wave is moving at 1/2 c relative to points x1 and x2, so the wave takes two time longer to to travel the same distance. But since the wavelength of the wave is fixed, and the wave is moving slower, it takes two times longer to see a complete cycle of the wave pass by. Since it takes two times longer for one cycle (wavelength) of the wave to pass by, the perceived frequency of the wave, relative to x1 and x2, has dropped by half. If the perceived frequency of the wave has dropped by half, and the perceived speed of the wave has dropped by half, then the number of wavelengths between x1 and x2 remain constant based on the equation I provided above.

The thought that if a wave is moving slower its frequency decreases is not hard to grasp. Just think that if the wave is moving slower, you have to wait longer for the crests of the wave to pass you by (because the length of one wavelength of the wave is constant).

Originally Posted by MagiMaster

I've got to ask, but what does the aether do in such a universe? What does it do, measureably?

First of all, the aether is the medium through which light waves propagate. They are longitudinal (ill explain later) waves which travel at a fixed velocity (c) relative to this medium. In terms of measurements, the aether is amazing. Because the aether would be perfectly at rest, its distance and time units on a cartesian axis are absolute, that is they do not change. The bad news is that unfortunately due to the effects of relativity, no material entity can ever determine whether they are truly at rest with respect to the aether or not, so while the aether obviously exists, we cannot compare our length etc. with respect to it because we cannot detect our motion through it.

Prosoothus,

This is getting ridiculous. Why do you keep harping on case 1 and 2, when they have no bearing on the MM experiment? The source is not stationary to the aether in the M_M experiment.

Look at the following animation, it is a source of light sittng between two dots (red and Blue) it is emitting waves of a set frequency. The wave travel outward at c as circles from the point of emission. In this first animation the source is stationary to the aether. The frequency and wavelength of the waves reaching the dots are the same.




Nowm same source, but moving to the right relative to the ether. The light waves still travel outward as circles at c from the point of the emission, but that point moves to the right as time gos on. The blue dot sees both the frequency and wavelength of the wave change as does the red dot. The frequency changes because each succesive wave is emitted a bit closer or further from the dot, and thus takes a shorter or longer time to reach it. The wavelength is changed because the speed of light relative to the dot hasn't changed, so wavelength must change if frequency changes.

If you arrange it so that the dots move with the source, then the frequency doesn't change as measured by the dots, but the dot's relative velocity with respect to the light does, so the wavelength still changes .



With the MM device, the light first goes one way with respect to the device's motion with respect to the aether, and then after being reflected from the mirror, the other way. Thus more wavelengths will fit one way then the other for the legs that run parallel to the device's relative motion. ( Assuming that there is an aether.)

Originally Posted by Waveman28

Originally Posted by MagiMaster

I've got to ask, but what does the aether do in such a universe? What does it do, measureably?

First of all, the aether is the medium through which light waves propagate. They are longitudinal (ill explain later) waves which travel at a fixed velocity (c) relative to this medium. In terms of measurements, the aether is amazing. Because the aether would be perfectly at rest, its distance and time units on a cartesian axis are absolute, that is they do not change. The bad news is that unfortunately due to the effects of relativity, no material entity can ever determine whether they are truly at rest with respect to the aether or not, so while the aether obviously exists, we cannot compare our length etc. with respect to it because we cannot detect our motion through it.

...

Ok, so if nothing can measure anything about the aether, then how can you know it exists?

Originally Posted by MagiMaster

..

Ok, so if nothing can measure anything about the aether, then how can you know it exists?

If NOTHING can measure anything about the aether, then why do you care if it exists ?

Janus,

This is getting ridiculous. Why do you keep harping on case 1 and 2, when they have no bearing on the MM experiment? The source is not stationary to the aether in the M_M experiment.

Let me clarify. First, you're right that if the source of light is moving relative to the aether there will be a shift in the frequency of the light. After that shift occurs, the light will be completely independent of the source. The light will travel at c relative to the aether, and at a specific frequency relative to the aether. Since this shift occurs before the initial beam even reaches the semi-silver mirror and splits up into two beams, this shift has no relevance to the result of the experiment since both beams are affected by the shift equally. In other words, not only can you completely ignore the first leg that the initial beam travels (to the semi-silver mirror), but you can also ignore whether or not the light source is moving relative to the aether because the light is still in phase (regardless of its frequency) since it hasn't been split into two separate beams yet.

The only parts of the experiment that you need to pay attention to is after the initial beam gets split into two beams by the semi-silver mirror. Since at this point the light is independent of the light source, all that matters is the speed (c) and frequency of the light relative to the aether. The speed of the light source becomes irrelevant from that point to the end of light's trip through the device. Case 1 and case 2 of my previous post apply to all points that the two beams travel throughout the device AFTER they were split by the semi-silver mirror.

Originally Posted by Prosoothus

The only parts of the experiment that you need to pay attention to is after the initial beam gets split into two beams by the semi-silver mirror. Since at this point the light is independent of the light source, all that matters is the speed (c) and frequency of the light relative to the aether. The speed of the light source becomes irrelevant from that point to the end of light's trip through the device. Case 1 and case 2 of my previous post apply to all points that the two beams travel throughout the device AFTER they were split by the semi-silver mirror.

Your problem is you are assuming the frequency relative to the ether is constant, even after the wave turns into the ether wind. It can't be the same relative to a moving ether as it was in the stationary ether, as it will undergo a doppler shift.

Harold14370,

Your problem is you are assuming the frequency relative to the ether is constant, even after the wave turns into the ether wind. It can't be the same relative to a moving ether as it was in the stationary ether, as it will undergo a doppler shift.

I'm stating that there is only one preferred frame of reference: the aether. Light always travel at a constant speed (c) and frequency relative to the aether. If an object is moving relative to the aether, the speed of the light and frequency of the light will change relative to the object. But, for any two points inside that object, the wavelengths of light between those two points will remain constant because the shift in the frequency of the light will be equal to the shift in the speed of the light for that object.

In other words, if the MM measured the speed of light or the frequency of light, it would work. But since it measures the wavelengths of light in the device, and the wavelengths of light remain constant for the reason I stated above, it does not work.

Originally Posted by Prosoothus

I'm stating that there is only one preferred frame of reference: the aether.

Okay, let's play that game. We will consider everything from the point of view of the ether.

Let's say there is a light source at a and a mirror at b. Points a and b are moving into the ether from right to left, i.e., the "ether wind" is blowing from a to b. The frequency and wavelength never change, from the perspective of the ether, but the source and mirror are moving. So in traveling from a to b the signal does not go a full wavelength because it is intercepted by b before it gets to b's original position. On the way back to a, the signal has to travel farther than one wavelength because a is receding from the position in the ether b was in when it reflected the light. Therefore there are more wavelengths of light in the path from b to a than from a to b.

Originally Posted by Prosoothus

Janus,



The only parts of the experiment that you need to pay attention to is after the initial beam gets split into two beams by the semi-silver mirror. Since at this point the light is independent of the light source, all that matters is the speed (c) and frequency of the light relative to the aether. The speed of the light source becomes irrelevant from that point to the end of light's trip through the device. Case 1 and case 2 of my previous post apply to all points that the two beams travel throughout the device AFTER they were split by the semi-silver mirror.

No that's wrong. You are ignoring what happens when the light is split into two different directions and what happens when the light traveling parallel to the movement of the device strikes the far mirror and reverses direction.

Start with a 500 terahertz(600nm) beam of light at the source. We will assume that the device is moving in the direction of the initial beam. The light will have its wavelength decreased and frequency increased with respect to the Aether. it reaches the half-slivered mirror. Since this mirror is moving relative to the ether, the frequency with respect to the mirror will revert to the original 500 terahertz. Meaning, that 1/5e14 second after the leading edge of a light wave hits the mirror, the trailing edge hits it. The wave length upon impact will be slightly less than 600nm (how much less depends on the relative velocity of the device to the ether.)
The particular wave we are interested in right now is one that is deflected at a right angle. The front of the wave strikes the mirror and is deflected upward. It travels upward at c relative to the aether. Since the mirror is not moving upward relative to the aether, it also moves upward at c relative to the the mirror. 1/5e14s later, the trailing edge of the wave reaches the mirror. In this time, the front of the wave has traveled c*1/5e14s = 600nm this is also its wave length relative to the aether, it reaches the mirror with one wavelength and leaves at a right angle with a longer one. It continues on until it strikes a mirror and is reflected back to the half-silvered one. since the second mirror is also not moving upward with respect to the aether, it reflects it back with the same frequency and wavelength.

Now consider the part of the beam that continues straight on. It eventually hits a mirror and reflects back the way it came. Again, due to the fact that the mirror has the same relative velocity with respect to the aether as the source, the frequency with respect to this mirror is 500 terahertz. The leading edge strikes the mirror with the trailing edge 1/5e14s behind. The leading edge bounces off the mirror heading in the opposite direction at c relative to the aether. But since the aether is moving in that same direction relative to the mirror, the light travels at c+v relative to the mirror, where v is the relative velocity between the aether and mirror. So when the trailing edge of the light wave reaches the mirror 1/5e14s later, the leading edge has traveled a distance of (c+v)/5e14s or slighty more than 600nm from the mirror. So by the time the trailing edge reverses direction to follow the leading edge it is more than 600nm behind and the wavelength has been stretched. The wave hits the mirror with one wavelength and leaves with another.

So you are wrong, the device will produce a phase shift if you assume an aether and it is moving with respect to it.

And don't come back with another attempt to "simplify things". All that does is cause you to ignore and omit important details that are needed to properly see what is happening.

Originally Posted by Janus

And don't come back with another attempt to "simplify things". All that does is cause you to ignore and omit important details that are needed to properly see what is happening.

Your arguments are flawless.

Your conlsusions are correct.

You have about as much chance of convincing this guy as an elephant has of hiding in the strawberry patch after painting his toenails red.

Originally Posted by Janus

So you are wrong, the device will produce a phase shift if you assume an aether and it is moving with respect to it.

And don't come back with another attempt to "simplify things". All that does is cause you to ignore and omit important details that are needed to properly see what is happening.

What does throwing out the assumption of an Aether give us, other than Lorentz contraction?

Couldn't we still have Lorentz contraction even with an Aether? Apparently light expands spherically, and that should mean a different part of the sphere is making contact with the mirror. That could make the distances slightly shorter, or longer, depending on how the angle of the beam changes. - Or at least it would seem so.

Originally Posted by kojax

Originally Posted by Janus

So you are wrong, the device will produce a phase shift if you assume an aether and it is moving with respect to it.

And don't come back with another attempt to "simplify things". All that does is cause you to ignore and omit important details that are needed to properly see what is happening.

What does throwing out the assumption of an Aether give us, other than Lorentz contraction?

Couldn't we still have Lorentz contraction even with an Aether? Apparently light expands spherically, and that should mean a different part of the sphere is making contact with the mirror. That could make the distances slightly shorter, or longer, depending on how the angle of the beam changes. - Or at least it would seem so.

Yes, we certainly can have Lorentz contraction and the aether. This is what I said in my of my previous posts in this thread, but unfortunately it fell apon blind eyes. The main point is that the aether is perfectly compatible with the concept of relativity. In fact, it is actually essential in order to understand what is truly going on and identifying the difference between the absolute, and the relative measurements that we record.

Originally Posted by Waveman28

Originally Posted by kojax

Originally Posted by Janus

So you are wrong, the device will produce a phase shift if you assume an aether and it is moving with respect to it.

And don't come back with another attempt to "simplify things". All that does is cause you to ignore and omit important details that are needed to properly see what is happening.

What does throwing out the assumption of an Aether give us, other than Lorentz contraction?

Couldn't we still have Lorentz contraction even with an Aether? Apparently light expands spherically, and that should mean a different part of the sphere is making contact with the mirror. That could make the distances slightly shorter, or longer, depending on how the angle of the beam changes. - Or at least it would seem so.

Yes, we certainly can have Lorentz contraction and the aether. This is what I said in my of my previous posts in this thread, but unfortunately it fell apon blind eyes. The main point is that the aether is perfectly compatible with the concept of relativity. In fact, it is actually essential in order to understand what is truly going on and identifying the difference between the absolute, and the relative measurements that we record.

This is getting off-topic. The original claim by Prosoothus is that the MM experiment would show a null result without having to introduce any relativistic (Either Lorentz's or Einstein's) corrections. This is not the thread to debate Lorentz vs. Einstein.

Originally Posted by DrRocket

You have about as much chance of convincing this guy as an elephant has of hiding in the strawberry patch after painting his toenails red.

You may be right. I just like to give everyone the benefit of the doubt at first. I hold on to some slight hope that if I chip away at it enough, he'll break through the mental block he's suffering from.

Then again, even my patience isn't infinite.

If you arrange it so that the dots move with the source, then the frequency doesn't change as measured by the dots, but the dot's relative velocity with respect to the light does, so the wavelength still changes .

If there is no motion between source and receiver there is no doppler shift, right?

If c is constant, and frequency changes so does wave length, right?

Aren't you confusing signal/emission frequency with light/radiation frequency?

Originally Posted by Janus

You may be right. I just like to give everyone the benefit of the doubt at first. I hold on to some slight hope that if I chip away at it enough, he'll break through the mental block he's suffering from.

Then again, even my patience isn't infinite.

Good luck in your chipping.

[

Harold14370,

Let's say there is a light source at a and a mirror at b. Points a and b are moving into the ether from right to left, i.e., the "ether wind" is blowing from a to b.

After considering what you said, I found that even though the number of wavelengths between a and be remain constant, the phase of the wave between those two points changes relative to the speed of the wave. I must have had a serious brain fart in order to not see this from the beginning.

So it appears that you and Janus are correct. The MM device really can measure the speed of light.

Originally Posted by phyti

If you arrange it so that the dots move with the source, then the frequency doesn't change as measured by the dots, but the dot's relative velocity with respect to the light does, so the wavelength still changes .

If there is no motion between source and receiver there is no doppler shift, right?

If c is constant, and frequency changes so does wave length, right?

Aren't you confusing signal/emission frequency with light/radiation frequency?

Remember, for the sake of argument, we are assuming an aether in this scenario.

With the source and receivers both motionless with respect to the aether and light moving at c relative to the aether, the receivers detect the same frequency, and measure the same speed of light relative to themselves(c). Due to the relationship between the speed of light, frequency and wavelength, they both measure the same wavelength also.

If the source moves relative to the receivers and the receivers remain motionless with respect to the aether, then each receiver detects a different frequency, and due to the above relationship, different wavelengths.

Now, if the source and receivers are at rest relative to each other, but moving at v relative to the aether and the light moves at c relative to the aether, then the velocity of light relative to either receiver will be be either c+v or c-v, depending on the which direction the light is traveling with respect to the motion relative to the aether. Thus while both receivers still detect the same frequency, one measures a wavelength of (c-v)/f and the other (c+v)/f.

These wavelength measurements will be the same as those in the last scenario. In the first case the wavelengths differ because the detected frequency differed but the relative speed of light was the same. In the second case they differ because the frequency was the same but the relative speed of light differed.

Originally Posted by Prosoothus

Harold14370,

Let's say there is a light source at a and a mirror at b. Points a and b are moving into the ether from right to left, i.e., the "ether wind" is blowing from a to b.

After considering what you said, I found that even though the number of wavelengths between a and be remain constant, the phase of the wave between those two points changes relative to the speed of the wave. I must have had a serious brain fart in order to not see this from the beginning.

So it appears that you and Janus are correct. The MM device really can measure the speed of light.

Glad I could help.

Originally Posted by Prosoothus

Harold14370,

Let's say there is a light source at a and a mirror at b. Points a and b are moving into the ether from right to left, i.e., the "ether wind" is blowing from a to b.

After considering what you said, I found that even though the number of wavelengths between a and be remain constant, the phase of the wave between those two points changes relative to the speed of the wave. I must have had a serious brain fart in order to not see this from the beginning.

So it appears that you and Janus are correct. The MM device really can measure the speed of light.

Congratulations, seriously.

You have demonstrated the ability to recognize a correct logical argument and change your mind accordingly. That trait is more rare than you might think.

Originally Posted by Prosoothus

I must have had a serious brain fart

I've been known to have those from time to time.

Originally Posted by Harold14370

Originally Posted by Prosoothus

I must have had a serious brain fart

I've been known to have those from time to time.

In my case I am often more engaged in limiting the bad smell than anything else. :?

Originally Posted by Janus

This is getting off-topic. The original claim by Prosoothus is that the MM experiment would show a null result without having to introduce any relativistic (Either Lorentz's or Einstein's) corrections. This is not the thread to debate Lorentz vs. Einstein.

What I'm considering is the possibility that the light bouncing off the mirrors would not properly obey the law of reflection.




In the illustration, if we assume the whole apparatus is moving toward the right, then as the blue part of the beam is first reflected upwards off of the half silvered mirror, is it possible that the angle of reflection might be slightly larger than the angle of incidence?

If the initial part of the beam, marked in red, has a non-zero width, then the bottom part of the beam is reflected upward slightly earlier than the top part of that beam. The fact the mirror is still in motion during this short interval of time means that every part of the beam after the first part perceives the mirror to be longer in the horizontal direction, based on how far it is having to travel in order to hit the mirror, as the mirror continues to move away.

I may need to start learning how to draw and upload images. Is it clear what I mean? If the mirror is in motion, then the distance between the horizontal location where the bottom part of the beam hits it and the horizontal location where the top part of the beam hits it is determined not only by the physical dimensions of the mirror, but also by the amount of time that elapses. The mirror acts as though it had been horizontally stretched, which means the rise of its slope remains fixed, but the run is longer, making it appear to face a different angle.

Basically, I'm thinking that if the angle changes, then the distance traversed changes as well. It would be interesting to compare the amount of added distance with the distance traversed by the green beam, and see if they're the same.

Originally Posted by kojax

Originally Posted by Janus

This is getting off-topic. The original claim by Prosoothus is that the MM experiment would show a null result without having to introduce any relativistic (Either Lorentz's or Einstein's) corrections. This is not the thread to debate Lorentz vs. Einstein.

What I'm considering is the possibility that the light bouncing off the mirrors would not properly obey the law of reflection.




In the illustration, if we assume the whole apparatus is moving toward the right, then as the blue part of the beam is first reflected upwards off of the half silvered mirror, is it possible that the angle of reflection might be slightly larger than the angle of incidence?

If the initial part of the beam, marked in red, has a non-zero width, then the bottom part of the beam is reflected upward slightly earlier than the top part of that beam. The fact the mirror is still in motion during this short interval of time means that every part of the beam after the first part perceives the mirror to be longer in the horizontal direction, based on how far it is having to travel in order to hit the mirror, as the mirror continues to move away.

I may need to start learning how to draw and upload images. Is it clear what I mean? If the mirror is in motion, then the distance between the horizontal location where the bottom part of the beam hits it and the horizontal location where the top part of the beam hits it is determined not only by the physical dimensions of the mirror, but also by the amount of time that elapses. The mirror acts as though it had been horizontally stretched, which means the rise of its slope remains fixed, but the run is longer, making it appear to face a different angle.

Basically, I'm thinking that if the angle changes, then the distance traversed changes as well. It would be interesting to compare the amount of added distance with the distance traversed by the green beam, and see if they're the same.

You are indeed correct. The angle of incidence will be different from the angle of reflection (but only from the perspective of the aether, which is the absolute point of view). However this has been known for over a century as was discovered by Hendrik Lorentz.

Originally Posted by kojax

Basically, I'm thinking that if the angle changes, then the distance traversed changes as well. It would be interesting to compare the amount of added distance with the distance traversed by the green beam, and see if they're the same.

I already mentioned that there would be a "drift" in the beam traveling perpendicular to the motion relative the Aether. But this will not change how long the beam will take to go back and forth.

Look at it this way, You are in a boat crossing 1 km wide river that runs East to West. You are traveling at 30 kph North relative to the water. It takes you 2 min to cross the river. It will take you the same 2 min no matter how fast the river is flowing. All the river will do is make you land downstream of where you started, it has no effect on how fast you travel across the river.

[quote="Janus"]

Remember, for the sake of argument, we are assuming an aether in this scenario.

Now, if the source and receivers are at rest relative to each other, but moving at v relative to the aether and the light moves at c relative to the aether, then the velocity of light relative to either receiver will be be either c+v or c-v, depending on the which direction the light is traveling with respect to the motion relative to the aether. Thus while both receivers still detect the same frequency, one measures a wavelength of (c-v)/f and the other (c+v)/f.

The pic shows the times of reception for R1 and R2 are equal. There must be an equal number of waves in each packet. Doesn't SR say wave number is invariant, you dont' gain or lose any.
drawing

Originally Posted by Janus

Originally Posted by kojax

Basically, I'm thinking that if the angle changes, then the distance traversed changes as well. It would be interesting to compare the amount of added distance with the distance traversed by the green beam, and see if they're the same.

I already mentioned that there would be a "drift" in the beam traveling perpendicular to the motion relative the Aether. But this will not change how long the beam will take to go back and forth.

Look at it this way, You are in a boat crossing 1 km wide river that runs East to West. You are traveling at 30 kph North relative to the water. It takes you 2 min to cross the river. It will take you the same 2 min no matter how fast the river is flowing. All the river will do is make you land downstream of where you started, it has no effect on how fast you travel across the river.

The difference is that, in my scenario, I'm assuming that you swim against the current in order to have the same heading you would have had if the water were still.

I'm predicting that the blue beam of light hits the upper mirror in exactly the same spot, no matter how fast the apparatus is moving in the right/east-ward direction. This is because the mirror appears to have been stretched in the horizontal direction, which makes it appear to have tilted slightly to the right, reflecting the beam in a direction that would be slightly more opposed to the current of the Aether/water.

The rise/run of the beam's heading is increased by an amount exactly proportional to how far the mirror will have moved before it arrives.

Originally Posted by kojax

The difference is that, in my scenario, I'm assuming that you swim against the current in order to have the same heading you would have had if the water were still.

I'm predicting that the blue beam of light hits the upper mirror in exactly the same spot, no matter how fast the apparatus is moving in the right/east-ward direction. This is because the mirror appears to have been stretched in the horizontal direction, which makes it appear to have tilted slightly to the right, reflecting the beam in a direction that would be slightly more opposed to the current of the Aether/water.

The rise/run of the beam's heading is increased by an amount exactly proportional to how far the mirror will have moved before it arrives.

That won't happen.

Imagine the mirror at a 45° angle moving to the right at v. The light is coming from the left at c relative to the aether. All this means is that the relative speed between the light and the mirror is c-v. There is no effective "stretching" of the mirror.

Originally Posted by phyti

Doesn't SR say wave number is invariant, you dont' gain or lose any.

Forget about SR. We were discussing how the device was expected to perform according to the known physics of the time.

to prosoothus,
i did not understand everything that you said.......
when the light gets transmitted through the half silvered mirror and travels to the right to the mirror along the rotation of the earth ...it should take longer to reach their as compared to when it goes back to the half silvered mirror on getting reflected in the opp. direction to that of the rotation of the earth.but these two effects would cancel each other and it would reach the other beam at the same time......
was that all what were you saying??as this thing has been troubling me for a last few days....

Careful with the search bar. This thread is 2 years old.

yeah yeah..