Was the Michelson & Morely experiment miss-interpreted?

[siarad]

It proved that the aether didn't exist & the speed of light was constant.<br />Albert Einstein professed not to have heard of it when day-dreaming up his Special Relativity.<br /><br />At a time when science knew all there was to know M & M set out to place the earth's position in space by triangulating it against the aether.<br /><br />A lamp sent light in two mutually interference free directions i.e. right angles, to be reflected back from mirrors when the round trip time could be measured. Shock horror! the returning light time was the same in both directions. What a wake-up call! science didn't know everything after all. Now the <i>assumption</i> behind this was that light & aether would act in the same way as sound & air. Based on this <i>assumption</i> aether was deemed not to exist. Just how scientific is that! do any of you think an <i>assumption</i> is a basis for good science.<br /><br />Now I don't know the history but it also seems that this experiment proved the speed of light was a constant too.<br />Look at the experiment, no matter in which direction either mirror was facing, the light would travel first with the aether & then against so wouldn't this cancel, or am I confused, so wouldn't the result have to be the same, aether or not, or even different speed of light in air.<br />A further worry seems to be that everything is in the same reference frame.<br /><br />I've asked before, does anyone know if the speed of light has been measured using a clock from a different time frame i.e. a pulsar maybe. I say this because measuring C by reflection seems wrong so measuring a transit would be more satisfactory but requires an external time-frame. Yes two synchronised clocks could be moved from the centre to each end to keep synchronisation, well I think it would, but I'm still not happy with that.<br /><br />Bradley in the 18th century measured C by a transit, of necessity in one direction only but didn't he assume the speed of gravity to be infi

 

[spacechump]

<i>Now I don't know the history but it also seems that this experiment proved the speed of light was a constant too.<br />Look at the experiment, no matter in which direction either mirror was facing, the light would travel first with the aether & then against so wouldn't this cancel, or am I confused, so wouldn't the result have to be the same, aether or not, or even different speed of light in air.<br />A further worry seems to be that everything is in the same reference frame.</i><br /><br />Well given that most physicist thought that the earth was moving <i>through</i> the ether then that meant that tests at right angles would show the light moving with or against the ether and then a perpendicular test would show light as ether moved through the beam "pushing" it. This didn't happen. There was no effect on the interference pattern at all at any angle. This has been done with much more up-to-date equipment over the past years showing the same conclusion. It doesn't matter if this was done "in the same reference frame" because the point was to test the earth's movement through the ether. It showed that light didn't care what orientation it was in.<br /><br /><i>I've asked before, does anyone know if the speed of light has been measured using a clock from a different time frame i.e. a pulsar maybe. I say this because measuring C by reflection seems wrong so measuring a transit would be more satisfactory but requires an external time-frame. Yes two synchronised clocks could be moved from the centre to each end to keep synchronisation, well I think it would, but I'm still not happy with that. </i><br /><br />Have you heard of GPS?

 

[heyscottie]

<font color="yellow">Now the assumption behind this was that light & aether would act in the same way as sound & air. Based on this assumption aether was deemed not to exist. Just how scientific is that! do any of you think an assumption is a basis for good science<br /><br /></font><br /><br />This wasn't an assumption at all! Aether was <i>defined</i> as the medium through which light travelled, and as the encompassing substance through which light would always travel at the same velocity.<br /><br />The fact that such a substance was found not to exist means that aether, as defined, does not exist.<br /><br />Scott

 

[siarad]

That's not what I said, the <i>interaction</i> was the assumption not existence but I see your connexion.

 

[siarad]

So my expectation that go & return would cancel is not true. I still can't get my mind around that. <br />GPS is subject to frame dragging surely & is corrected for SR & GR on the assumption that C is constant negating its use in proving C is constant.

 

[spacechump]

Well if GPS wasn't corrected using GR and SR then it would be useless to us as it wouldn't be accurate. Given that SR and GR are based on the fact that C is constant and that those calculations work to correct against error, don't you think that is a strong case in proving C is constant? I mean, how would you go about using a pulsar? <br /><br />Edit: And it is in two different reference frames (ground atomic clocks compared to orbital atomic clocks)so that solves that problem as well.

 

[unclefred]

The Michelson & Morely experiment proved that the speed of light in the apparatus was constant in all orientations and thus the theory of ether was wrong. Similar tests (don't know if Michelson & Morely ran them but they could have) have shown that the speed of light depends on the temperature and humidity of the air. It also depends on the velocity of the air. Fill the interferometer with anything and you find the speed of light depends on the properties of the media you used to fill it. Fill it with water and the speed slows appropriately. The experiment did not show that the speed was a universal constant, but it sure points that direction.<br /><br /> Note that the Michelson & Morely experiment experiment could be repeated using sound instead of light and one gets the same result, and that is that the speed depends on the medium inside the interferometer and is the same in all orientations. Light has one property that separates it from sound and that is that it can travel in a total void or vacuum. Measuring the effect of the temperature or velocity of the air in the interferometer is easy. But when one puts the interferometer in a vacuum, measuring the effect of the temperature or velocity of the vacuum becomes meaningless. Thus one cannot prove that the speed of light is constant in a vacuum untill one answers the question "constant with respect to what?" How can one heat up a vacuum? How can one accelerate a vacuum? What if the vacuum is moving at a speed close to C? All meaningless questions.<br /><br /> Measure the photons that were generated in galaxies moving a warp speed or measure the photons from your desk lamp and you will get the same answer. Measure the photons hitting you as your spaceship is traveling at 0.9 C and you will get the same answer. The speed of the photon is totally a function of the medium inside you test setup. The old distance divided by time. We know of no difference in the photons produced

 

[igorsboss]

<font color="yellow">Given that SR and GR are based on the fact that C is constant </font><br /><br />That's a postulate, not a fact. Where the postulate is false, the theory yields an incorrect model.<br /><br />Although we have never observed a situation in which the postulate is false, we can't prove we never will.

 

[spacechump]

Unclefred,<br /><br />Learn QED and get back to me. What you stated only works in classical situations but not under quantum mechanics. Photons always travel at c. What you see when light slows in a medium is a delay of absorption and retransmission between atoms. The temp of a vacuum doesn't effect the photons velocity of c.

 

[unclefred]

I have seen this explanation before of why light appears to slow down in a medium as being "absorption and retransmission between atoms" but this theory has many problems. I believe you are misstaken. How is it that the light is absorbed and re-emitted with exactly the same properties (i.e. phase, direction, polarization, etc)? How is this done and still be consistent with the fact that atoms can only absorb and emitt photons with specific energies (Einstein got a Nobel prize for this)? The only place I know of that this absorption and re-emission process takes place is in a laser. Can you provide a reference for your theory? <br /><br />Your statement "The temp of a vacuum doesn't effect the photons velocity of c." is interesting. How do you know? How do you increase or decrease the temperature of a vacuum? How do you measure it? I said that such statements were meaningless. What point were you trying to make?

 

[spacechump]

<i>How is it that the light is absorbed and re-emitted with exactly the same properties (i.e. phase, direction, polarization, etc)?</i><br /><br />First off it isn't the same direction. Think of where refraction comes from. It is the shedding of a bit of momentum from the photons as they pass through a transparent substance to balance the conservation of momentum. For most substances photons of certain energies collide with electrons, which are then absorbed and retransmitted in a different wavelength depending on the initial photon energy and the orbital jump of the electron as it jumps back down from a higher orbital. This is how lasers work; light amplification through stimulated emission of radiation (LASER). But for a transparent substance there is no clear energy jump for the outer electrons to take when photons strike them. So after absorption the electron retransmits it but in the process of the retransmission a bit of momentum is shaved away but that is all that changes because the electron had no chance to jump into another state.<br /><br /><i>How is this done and still be consistent with the fact that atoms can only absorb and emitt photons with specific energies (Einstein got a Nobel prize for this)? The only place I know of that this absorption and re-emission process takes place is in a laser. Can you provide a reference for your theory?</i><br /><br />The photoelectric effect is for metals.<br /><br />Quantum electrodynamics links:<br /><br />http://en.wikipedia.org/wiki/Quantum_electrodynamics<br /><br />http://www.science.edu.sg/ssc/detailed.jsp?artid=2580&type=6&root=5&parent=5&cat=54<br /><br />http://www.newton.dep.anl.gov/askasci/phy00/phy00283.htm

 

[unclefred]

Thanks for the links. A little searching and I found several more that seem to agree that the slow down in apparent speed comes from absorbtion and re-emission.<br /><br />As you pointed out my reference to the photoelectric effect was wrong. I was actually thinking of the emission lines and absorption lines in stelar spectrum that show that light is absorbed and emitted at specific wavelengths. Sorry for the confusion.<br /><br />I beg to differ with you, and again state that the re-emitted photons must have exactly the same properties (i.e. color, phase, direction, polarization, etc) as the original photon and there cannot be any refraction (bending) or scattering. If the light output was not absolutely identical to the input light, then simply putting a glass window in a beam would destroy all of its properties. We know that the properties are maintained or virtually any optical instrument with a lens or window would not work. If your statements are correct, the glass output window on a laser would immediately scramble the light it would no longer have laser properties.<br /><br />As for refraction, that happens only at the interface between two indexes and only when the light is moving at an angle to the index change. Light hitting perpendicular has no direction change. We are talking about the apparent speed inside the medium, not at the interfaces. Thus refraction is a completely different subject.<br /><br />I have to disagree with your statement "For most substances, photons of certain energies collide with electrons, which are then absorbed and retransmitted in a different wavelength depending on the initial photon energy and the orbital jump of the electron as it jumps back down from a higher orbital." This close to what I was referring to in my previous email (and unfortunately referenced the photoelectric effect) and that is precisely NOT the mechanism that is being referenced as the cause of light appearing to slow down. From your references (and