In the Michelson-Morley experiment, a beam of light was split in two perpendicular directions relative to the ether. It was expected that the two beams, when brought back together, would create an interference with each other that could be measured. From this, we could determine our velocity through the ether. But the beams showed no interference. So Einstein then declared that if we cannot detect the ether, then why suppose one to exist in the first place? He then came up with his SR theory accordingly. Let's take a look at how all this came about, shall we?

In Understanding Physics: Light, Magnetism, and Electricity by Isaac Asimov (page 91), Asimov goes into detail about how the Michelson-Morley experiment was set up. He explains that for an apparatus that is facing the direction of the Earth travelling through the ether, the beam that is travelling directly into the ether (with the Earth) would do so in a time t=d/(c+v) and then t=d/(c-v) travelling back, for a total time of t₁=2dc/(c²-v²), where v is the velocity of the Earth through the ether. The perpendicular beam would do so in time t₂=2d/(c²-v²)^1/2. The distance d for both beams is the same and is the distance from the point where they are separated to the reflecting mirror that brings them back together again. The total ratio of times between the two beams is t₁/t₂=1/[1-(v/c)²]^1/2.

Now let's look at SR. In On The Shoulders of Giants by Stephen Hawking (page 1171), which is a reprint of Einstein's Principle of Relativity ("On the Electrodynamics of Moving Bodies"), Einstein considers a rod that is moving at a velocity v relative to a stationary system. The time that it would take light to reach an observer on each end of the rod would be t=d/(c-v) and t=d/(c+v). Then he considers the rays moving along the other two axes as t=d/(c²-v²)^1/2. He comes up with a dilation between them of 1/[1-(v/c)]^1/2. Sound familiar? If we consider the "stationary system" to be an ether, we have the exact same concepts and formulas for them.

So what is going on here? How can Einstein declare there is no ether and then find the exact same formula? If he is saying that the results can be found without an ether, then shouldn't the Michelson-Morley experiment have still found this for the interference, which amounts to the same thing? In other words, why doesn't SR, then, work out for the result of the experiment instead of the null results? If he is saying that SR cancels out the result of the ether exactly so that we see no difference, then wouldn't that mean that the ether still exists?

Well, the answer is much simpler than all this. The reason is that Einstein's thought experiment and the Michelson-Morley ether experiment are both flawed. Did I just say that? Yes, I believe I did. Thank goodness for the ATM section of this forum, because elsewhere that might be considered heresy (probably is anyway). You see, in both cases we are considering what we would see according to the velocity of the moving object, the Earth which moves through the ether or a rod moving relative to a statiory system. But they both forgot one very important part. One must also consider the motion of the observer.

With the Doppler shift, we consider not only the motion of the source, but of the observer as well. Consider what is happening here. The observers in Einstein's thought experiment are moving with the rod. Also, the apparatus used in the Michelson-Morley experiment is moving with the Earth, and so are the experimenters. We all know that the Doppler shift will have an effect of making a train whistle sound more high pitched when moving toward us and deeper pitched when moving away. This is what these two experiments are based on. But what is it that they are really doing? That's right. They are perfoming the experiment while riding on the train itself. So of course no difference will be observed. The train's whistle will sound exactly the same as if it were stationary to us, because it is.

__________________
Let's put together the pieces of The Grand Puzzle . (website)

"Let's define another operator, Sz, which we won't pay any attention to."
"This transformation will automatically make zero equal zero."
"It may be true that zero equals zero -- and that is certainly an equality -- but I don't want to go into the details at this time."

Hi grav.
Your observations are interesting. There is a "space dragging" around a mass.
That way we are moving with our Earth's space. There is not an absolute eather but there are local relative eathers (space recession in Universe).

see my thread...."inertial field theory".


inertial field theory.

A good idea. The space is joint to a matter.
Michelson-Morley experiment in one reference frame (on the Earth in equal gravity) shows constant speed of light. There is different situation if we measure a speed of light on a sea level and 10 km higher. There is a time dilation - Rebka experiments in Harvard. A Quasar jet may emit much faster light then we measure here on the Earth.
We have to know what is the space realy.

Because the presence of an ether would come out as the difference between the two times :

t2 - t1 = 2d/(c2-v2)1/2 - 2dc/(c2-v2)
= approx (2d/c) * (v*v/2*c*c).

(sorry - one day I'll learn how to do superscripts!)

First off, can we agree on a web site that we can discuss, rather than books (which I don't happen to have). For MM, I suggest this one.

To see what MM were doing, let's continue with the train example - a train with open carriages.

First, we'll have our train running along at speed 'v' on the moon. We stand 'd' metres from the front of the carriage, and there's a wall 'd' metres to the side. As we throw a ball to the front and side, we would expect that there would be no difference in timings (after all, it's effectively in a closed box)
ie. t1 = t2, so t2 - t1 = 0.

Now picture our train on Earth. This time, we feel the air flowing in our face at speed 'v'. Although we ignore air-resistance per-se, what would happen is that the ball would get caught up and flow backwards with the air. This would make the cross-wise throw take even longer than the forward by the t2 - t1 difference above.

MM expected that, with v="speed of earth around the sun", they'd find this t2-t1 time difference. However, what they found is that that there WAS no difference - ie. t1 = t2. That's equivalent to our train on the moon - ie. no air for the ball to sit in - and so there's no aether that the light flows in.

In SR, ALL you consider are the relative motion between sender and observer. That's hardly "forgotten".

Incidentally, you've referred a couple to times to Doppler Effect. Do you have a page that describes what you're proposing (and yes, ATM is fun )

Madman,

The local frame dragging you seem to be proposing sounds to me like light that travels with the source (plus the speed of light, of course). This is also another possibility I initially considered for the null results of the MM experiment. If we consider that light is always emitted from atoms at the speed of light relative to the atoms themselves, then all we need to consider after that is the relative velocity of the observer, which will see the light either blueshifted or redshifted. If the observer is travelling with the source, no difference will be seen here either.

So the only real difference between what you are proposing and what I propose is determined by whether light is a wave or a particle. If it is a wave, it will travel through the ether at an absolute "speed" wave velocity, but the Doppler shift causes it to be measured at this speed regardless. If it is a particle, it will travel at the speed of light relative to the atoms that emitted it plus the speed of the particles themselves (local frame dragging). The problem with this is that the atoms in a gas can travel in many directions at many speeds, and then so should light. But light can be considered a particle in some ways and a wave in others. It has all of the necessary features of a wave, so I tend to think of it that way. The only real tendency for it to act like a particle is when we measure the energy of individual photons. But then, what is a photon really? It is the energy that exists between successive pulses, or successive waves. In other words, it is the energy that exists from wavecrest to wavecrest for light.

Unless I am forgetting some important aspect of the Doppler effect, we can determine whether it is a particle or wave with a simple experiment. We can construct a twenty meter pole with a laser on one end that is aimed at a screen on the other. We can then turn the pole in different directions and mark where the laser strikes the screen accordingly. If the Earth moves through an ether, the laser should strike the screen slightly back from the direction the Earth is moving. After turning the pole in all possible directions, we should have a filled in circle drawn on the screen. The ratio of the radius of the circle to the length of the pole will be the same as the ratio of the velocity of the Earth through the ether to the speed of light. Also, we can find the direction of the Earth by finding the direction of the pole where the laser strikes the center of the circle. But actually, this can only prove the existance of an ether if it works and that light moves as a wave (independant of the local frame). If it were to produce a null result, I would probably then only consider what Doppler effects could produce this null effect for waves as well.

__________________
Let's put together the pieces of The Grand Puzzle . (website)

"Let's define another operator, Sz, which we won't pay any attention to."
"This transformation will automatically make zero equal zero."
"It may be true that zero equals zero -- and that is certainly an equality -- but I don't want to go into the details at this time."

RobA,

Actually, you have to divide those two times to get a ratio of the frequencies. A difference in times is absolute. But that makes sense, too, really, to find the total destructive interference. But that's not the way they chose to do it. My main concern in all of this is how does Einstein propose the same concepts, formulas, Doppler shift, Loretz contraction and so forth that is used for the concept of an ether to explain the null results when the same ones didn't work out in the experiment in the first place? If they show how the effects of the ether can be cancelled out, then there is still an ether. And how does he intend to show this by simply recreating the same formulas all over again? If there is no ether, then the MM experiment should at least verify SR by the same methods. But it shows a null result. Simple reasoning says that this is because the observer is moving with that which we are trying to measure. This would produce null results regardless of which methods we are using.

I have been attempting to provide an explanation using the Doppler shift for the effects we presently ascribe to relativity, such as gravitational lensing and gravitational redshifting. I thought that would be difficult to do, but it has taken me all of a day and a half so far. And I got them the first time around. Not too difficult after all. I was going to wait a little while and see what else I can determine, but I guess I'll go ahead and post what I have so far. I will do this tomorrow, the first chance I get.

__________________
Let's put together the pieces of The Grand Puzzle . (website)

"Let's define another operator, Sz, which we won't pay any attention to."
"This transformation will automatically make zero equal zero."
"It may be true that zero equals zero -- and that is certainly an equality -- but I don't want to go into the details at this time."

You are correct here Grav. This is the key, and is exactly what is being discussed in the Conservation of energy thread in Q&A, and was briefly introduced by Publius in the MOND thread.

Mr Cahill has identified and almostly correctly defined the 'background' gravitational field that is independent of the baryonic matter gravitational interactions of galaxies. Also, as I suggested in the MOND thread (which no one seemed to notice or take heed of), none of the DM or MOND like affects can be seen in the solar system (at least for the planets' orbits) because 'space', the aether, the background field, whatever you want to call it, was not affected/effected when the solar system was formed.

So, for a Michelson/Morley type experiment, it would have to be earth being compared to movement in the 'greater' (than our galaxy) background gravitational field.

__________________
RussT
________________________________
Everything is, as it should be, otherwise, it wouldn't be!

And this velocity is IIRC ~300 km/s. We don't see this either in these types of experiments.

__________________
Microsoft is over if you want it.

The bar has been lowered for the promotion of ATM ideas; the bar for the acceptance of ATM ideas must remain high.

grav
kind of...although i refer to it as an "inertial field"....instead of "frame dragging" (which implies a "warping of spacetime" according to einstein).

and also not "source"..(which implies emission).

to clarify:
according to my theory, space (and even matter) would be considered as discrete zones of inertial rest...light velocity is referenced to, and travels through those zones/fields, as if they're fixed coordinate spaces.

but in deference to the "emitter theory", there would be no addition to the velocity of emitted light caused by the relative velocity of an emitter itself.

instead, as light passes from one inertial field to another it takes on a velocity that is referenced to the inertial moment of whichever field (or material) it traverses.

************************************************** **

grav
you must also consider how the light moves in regards to the inertial properties of a discrete coordinate space.



to think of "motion of light relative to the rest moment" in another way?

consider the inertial rest moment of matter on earth....if you were to drive your car at 60kph on a flat road, you would find that there is no advantage in the choice of direction taken...(ie: it costs the same energy to travel at the same speed regardless of the earth's spin).

if you were to run into a brick wall..it wouldn't matter if you were heading north, south, east or west...you would still hit at 60kph.

the same with light...it doesn't matter which direction you emit light...it remains the same frequency.

this is a strong indicator that light motion (in air) is referenced to the inertial rest moment (of the earth) in the same way as matter and sound motion is.

the proof of this is displayed by the m&m interferometer.

when the experiment is executed "correctly" (ie: kept perfectly still)...we get a negative result (for doppler shift)...but if the interferometer is bumped, we get a positive result.


m&m chose to focus solely on the result of the "correctly" executed experiment (ie: the un-bumped interferometer)...and einstein chose to enforce it with his 2nd postulate of sr.

but the bumped interferometer has a different story to tell....one that is incompatible with the result of the correctly executed m&m experiment....and this shows us that that "singularly assumed correct result" should not be enforced at all times...since it does not speak for all conditions of relative motion.


in trying to enforce the singular negative result of the correctly executed m&m experiment, einstein has generated a theory that seeks to speak for accelerated as well as non-accelerated frames (ie: all conditions of motion...since both he and m&m assume a motion of the interferometer through a background coordinate space).

but as we can see with the "bumped interferometer", a real relative motion or acceleration, actually returns a positive result...not the negative result that einstein seeks to enforce.

and from this "positive result" we acquired the "proximity fuse" which enabled effective anti-aircraft ballistics for warships in ww2...and also "doppler radar" which was only declassified around 1950.

neither of which should be feasible according to einstein...since he enforces "the result of the correctly executed m&m experiment"...which promotes an unvarying frequency, regardless of velocity/direction/acceleration (ie: under all conditions of motion).

**********************************************
grav
no.

i define a causal link between light motion and the inertial rest moment of mediums/coordinate spaces...not a relationship to a general "ether".


it wouldn't matter if light were a particle or wave...it is instead "motion relative to the inertial rest moment of light" that returns a positive result...as can be seen when the interferometer is bumped...or a police officer uses a radar gun.

It is possible to measure the space dragging around the Earth
http://www.cnn.com/2004/TECH/space/1...eII/index.html
Our Earth moves slowly with its space together and there is not a relative movement toward a local eather.

Let's keep discussion (and challenges) on this thread to grav's ATM ideas, shall we?

Other ATM ideas can be presented, discussed, challenged, etc in threads each devoted to those ideas.

Very interesting. Thanks.

What is not often said about the MM experiment is that back in those days, physicists and astronomers thought the universe was “fixed” and unmoving, and not expanding or contracting. They also thought that the “ether” (some sort of “light-propagating medium”) was “fixed” with universal space. They thought most of the stars were “fixed” too and didn’t move. So, they thought the earth was moving through the “ether” at about 18.6 mps, in its motion around the sun, and no motion of the sun was considered during the MM experiment.

The classical Doppler effects of the 19th Century required some sort of light wave-speed-regulating “medium”. For example, if an observer is moving through a medium toward oncoming light, and the emitter is not moving relative to the medium, the wavelengths in the medium are normal and the light speed is normal in the medium, but the blueshift that is observed by the moving observer is due to the increase in the relative speed between the observer (moving toward the light) and the oncoming light (moving toward the observer). Thus, the moving observer receives the light at a combined speed of c + v, which causes the blueshift (according to the 19th Century theory).

On the other hand, if the moving observer is moving away from the light source (in the 19th Century way of thinking), while the emitter is stationary in the medium, the light speed and wavelengths are “normal” in the medium, but since the observer is moving away from the light source, he receives the oncoming light waves as being redshifted, because he receives the light at an observer-relative speed of c – v.

But that’s just one of the two main Doppler effects. The other one is just as important. That’s is when the emitter is moving through the medium, and the observer is stationary in the medium. When the emitter moves away from the observer (according to the 19th Century Doppler theory), the light waves are “stretched out” in the medium. When the emitter moves toward the observer, the light waves are “compressed” in the medium. In other words, the light waves are compressed in front of the moving emitter and are stretched out in the rear of the moving emitter.

So, in this second case, we have longer and shorter waves in the medium that causes the red and blueshifts at the medium-stationary observer. Whereas in the first example, we have normal-length waves in the medium, traveling at the normal speed in the medium, while the observer’s motion and the change in the relative speed of light (relative to the observer) is what causes the red and blueshifts.

This 19th Century explanation of the Doppler effects is supposed to now be obsolete.

Regarding sound from a moving train whistle, the waves are actually stretched out in the medium (the air) toward the rear of the whistle (see Doppler effect #2 above) while the train is moving through the medium, but the observers at the rear of the train are moving toward the oncoming and stretched out sound waves at a combined speed that is greater than the normal speed of sound in the medium.

So while the sound waves they receive are stretched out in the medium, they don’t notice it because they are moving toward the oncoming sound waves, while the waves are moving toward them, and they receive the stretched out sound waves at a speed that is faster than the normal speed of sound through the medium. This is why they hear the normal pitch of the whistle sound.

Seems that Doppler effect #2 (stretched-out sound waves) is canceled out by Doppler effect #1 (the c + v phenomenon caused by the observers moving toward the oncoming sound waves). These two effects perfectly cancel each other out at the moving observers moving through the medium on the train that is moving through the medium. This part of the 19th Century Doppler theory is still retained today.

I am not sure which velocity you are referring to here Celestial...the earth around the sun, the suns rotational velocity in the MW's orbit around the galactic center, or our galaxies velocity towards the Great Attractor, Virgo?

But I don't think that is the key anyway.

The key is, that our galaxy and M31 and all the rest of the galaxies are moving in 'some' velocity in the 'background' field together. The Cahill paper is showing this in a pretty dramatic way.

Actually, Celestial Mechanic, I believe your expertise and GR knowledge would
tremendously benefit further understanding for me, Publius and Ken G in that thread.

__________________
RussT
________________________________
Everything is, as it should be, otherwise, it wouldn't be!

But that is exactly how they chose to do it, because it was the difference in times that they were after. They wanted to see if how much longer one path took than the other, and to do that they merged the light beams (akin to the 2-slit experiment) to get the interference pattern. The light frequencies - let alone the ratio - didn't enter into it. Asthe link says (emphasis mine) :

Well, the same concepts and formulas come about because, as you correctly pointed out, SR and MM both use basically the same geometry.

However, in MM's time, there was a problem because this geometry was expected to give different different travel times due to the the aether, because mathematically (t2 - t1) > 0. However, Nature didn't cooperate , and gave us t2-t1 = 0. Einstein's insight was that this could be explained by having no aether, instead having time and distance vary by the ratios demanded by that same geometry. So it's not surprising there's a lot similar.

No, the experiment's results basically ruled out an aether (although it took Einstein to realise it, rather than adding another epicycle).

Sorry - I must admit I'm not sure what you're saying here. MM showed that light travels at the same speed in all directions (regardless of the motion of the earth), and therefore there's no universal aether that light travels in. It was an experiment done with light, whereas SR encompasses everything at all (constant) velocities. Do you mean we should be able to perform an MM-type experiment with objects travelling under-c? If so, I'm sure you can guess my answer (muons hitting the atmosphere, particles in accelerators, etc)!

Which is fine - except if there's an aether, it would be flowing past us - or rather, Earth would be flowing through it. MM wasn't a one-off experiment - it was and is being performed at all times of the year (with earth changing direction by 180 degrees over 6 months).

Or do you mean that Earth drags it's bit of aether around with it? If so, shouldn't the effects be visible when we shine light out (eg. lasers to the moon)?

Fast work - puts my little SR calculation in the other thread to shame
I look forward to seeing it.

This thread is getting very interesting. Thank you all for your replies so far. I have a feeling I'm going to be learning a lot from all of you. I think I have come up with a couple of things to contribute as well.

First of all, let's start with the Doppler shift. The formula for it is f_observed=f_emitted[(V+v_o)/(V-v_s)], where v_o and v_s are the velocities of the observer and the source in respect to the medium. Each are considered positive when moving toward the other. V is the "sound speed". If we consider a source and observer to be moving together, then we can consider v_s to be positive and v_o to be negative, then, since it would then be moving away to keep the two stationary relative to each other. So v_s=-v_o. The Doppler shift formula then becomes f_obs=f_emit[(V-v)/(V-v)] or f_emit[(V+v)/(V+v)] (depending on which we consider positive or negative) =f_emit. So no difference is seen regardless of the system's motion through the medium. But with some relative velocity between source and observer, it is then theoretically possible to obtain an absolute velocity in respect to the medium using the Doppler shift equation.

As far as an inertial frame, if we think of a ball tossed up while standing still, the ball will remain stationary to the system and fall straight back down. If we were riding in a car and threw the ball up, it would then move with the "emitted" speed plus the speed of the car, and still remain stationary to that system. That is why the ball doesn't go flying backward when we toss it. But that would make light a particle, and it would then bend in a gravitational field according to Newtonian gravity for particles. This is not the case.

If light is massless, then it is simply the additional energy of the medium that is displaced. If the same thing also creates gravity, then light will be effected by it. In other words, if absorbed neutrino pressure from the neutrino medium creates an imbalance between inward and outward pressure in a body, then this would be felt as gravity. The mean neutrino paths are then increased in the direction of the body, so that they tend toward that body as well, and so does their apparent energy waves. The light would always travel at the same sound velocity through the neutrino medium, so they are not affected the same way as particles would be. For particles, their velocities change according to the gravitational field present. Not so in the case of light. Let's explore this.

When a particle travels perpendicularly to a massive body, it first speeds up as it approaches it and then slows down afterward. But light maintains a constant speed, so it is effected by the body to a greater degree because it remains in the immediate region of the body longer. If we imagine a right angle where one side is the tangent distance from a body (point of closest approach = R), we can count off distances on the other side (along the line of motion) with c*ti, where ti is some infinitesimal time of travel where the speed of light does not slow down. At ti*n, the light is at some distance d=[R^2+(c*ti*n)^2]^1/2. For small M/R ratio for the body, the velocity gained perpendicularly to the line of motion of the light is small, but will also lose some forward velocity in such a way that [v_forward^2+v_{perpendicular}^2]=c^2. In other words, the light path will curve.

The total acceleration of gravity that acts on the ray of light at any particular point is a=GM/[(R^2+(c*ti*n)^2)^1/2]^2. But the amount that acts perpendicularly to the line of motion only is a=GMR/[(R^2+(c*ti*n)^2)^1/2]^3. The velocity that is gained in this perpendicular direction during each time interval is v=a*ti. So the total velocity gained for the ray of light while travelling from the point of closest approach to infinity is the sum of the integral of ti*GMR/[(R^2+(c*ti*n)^2)^1/2]^3 for n equals one to infinity and ti approaches zero. I found that this infinite summation (using Ubasic) becomes equal to (GM)(2/cR-3ti/R^2) for very small ti. For ti=0, it is obviously just (GM)(2/cR)=2GM/cR.

Since we have only considered the path starting from the tangent point, and since the path that led to the point of closest approach is identical to the path afterward (hyperbola), this makes the total velocity gained perpendicular to the line of motion equal to v=4GM/cR. This is for the side of the right triangle that expresses the change in velocity in respect to the bending of the path of the ray of light. The resultant side is c at all times. So to find the total angle through which the ray has bent, we simply find sin^-1(4GM/rc^2). This is exactly twice that of the Newtonian value for particles, and exactly equal to Einstein's predicted value. But now, there is something else. Einstein's value is only the minimum value for light. That is, it is correct for when M/R is small, as with our sun. For very large M/R values, as with black holes, the bending of the path of the ray of light itself will cause it to stay within the vicinity of the massive body even longer than that, so the angle over which it is bent is even greater.

Now let's consider light travelling directly out of a gravitational field. Since light will not slow down or speed up, it will only lose or gain energy according to its frequency. For particles, this loss of energy would be E_r-s=GMm(1/r-1/s) for a change in distance from r to s from the center of a massive body M, where m is the mass of the particle. Light doesn't have mass, but it can be "represented" by m=hf/c^2. So now we have E_r-s=hf_o-f=GM(hf/c^2)(1/r-1/s). The redshift is the ratio of the change in frequency to the original frequency, so the reshift is z=(hf_o-f)/hf=(GM/c^2)(1/r-1/s).

Again, particles will lose velocity when propagating against this gravitational field. If they lose too much, they will fall back in. Light, however, will not lose kinetic energy, but only frequency. This tells us something about black holes as well. A black hole, then, cannot trap light this way. It can only reduce the frequency to such a degree that the light cannot be seen. One might argue that for gravitational lensing at least, the light will curve to such a degree that it becomes trapped, but this is not true either. It is only true when the light originates this way, in which case it will orbit endlessly. But for light that approaches a black hole from space, the angle at which it curves toward the black hole originally is exactly the same as the one at which it curves after passing the tangent point. From the point of view from the tangent point (point of closest approach) it is symmetrical in both directions, coming and going.