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The
very crux upon which relativity stands! Regardless of the
repetitions which followed, this is the experiment upon which
the second postulate of special relativity is based. While
Einstein claimed at one point, many years later, that he was unaware
of this experiment at the time of his development of Special
Relativity, there is no question that the Lorentz equations so
central to SR were developed by Hendrick
Lorentz specificially because of
this experiment. Those equations require light speed to be
constant to have any meaning at alll
whatsoever. Einstein's assertion of his ignorance of
this experiment only serves to bolster claims that his work was
purely plagiaristic in nature. Without this experiment there was no
reason to postulate light
speed contancy
in the first place.
There exists the claim that
Einstein's idea of light speed constancy came from Maxwell's
Equations and that they somehow
required frameless constancy. This is utter nonsense since Maxwell
formulated his equations based upon the assumption of an ether with
a permitivity a permeability. (still in use today) It
is tantamount to saying that Galilean
Relativity was Einstien's motivation for postulating light speed
constancy. However Galilean Relativity assumed carrying a medium
along with the experiment. IE: While Galileo's example was in a
ship, we'll take sound inside a jet as an example.
It travels at the speed of sound in the jet's "frame" because
the medium (air) is taken along with it. However, if a hole is
cut in the front and back of the "ship" so that air can pass
through, Galilean relativity no longer applies. At the time of the
inception of SR ether was nearly one-hundred years of scientific
fact and this medium, would behave much like air. There is
absolutely no inspiration for light speed constancy to be found in Maxwell's equations or
in Galilean relativity all. The only inspiration would have to come
from pure imagination of a counter-intuitive process with no example or
use in human experience or it had to be this experiment.
Hopefully this makes the answer clear enough for
you.
The
"null" result of this experiment is what gives credence to time
dilation and the host of other paradoxical properties of relativity.
This experiment was the only reason SR was given any
consideration by the scientific community of the
time. Unfortunately, the experiment was very very far from
null. It was smaller than expected but the ultimate answer, the
speed of the ether wind, was only one-third what was expected.
Because of the way relative velocities work combined with the
construction of the interferometer, all that can be detected
is something called a second order effect. This means the main
effect is mainly cancelled out and a much smalled effect is
left. If Michelson, expected a speed one-third of his
original expectations he would expect a "reading" around
one-tenth of his originally expected reading.
If some of this is already
starting to sound confusing, do not despair, I will explain these
concepts in great detail to help you understand all the
ramifications of the experiment and subsequent experiments of the
same kind. Here is a good explanation of the experiment as it is generally accepted
by the masses. I recommend having a feel
for the "accepted" (biased) view before moving
on.
False
Claims
The Experiment Was Null:
The most common cutoff point used in various areas of scientific
study is in the area of 5%. While I will call into question the
original analysis of the data conducted by Michelson, his analysis
showed not less than one-sixth to one-fourth the expected effect.
This is 16-25% and well beyond the accepted norms for "null". Only
the repeated heralding of Arthur Eddington in spoken and written
media caused the faulty repeating of the MMX as "null".
The Readings Obtained
were Within the Error of the Experiment: The first time
Michelson attempted to perform this experiment, the device he used
would only show a resolution within one-tenth of a wavelength. This
older failed experiment is of little consequence and is never
thought of as the "Michelson Morley Experiment". Only the 1887
experiment is of scientific significance and is widely accepted as
the experiment that was null or within error range. However, the
error range reported by Michelson in the subsequent paper was
one-hundreth of a wavelength or "fringe". Even the highly averaged
and dubiously compared reading he reported was over four times that
error level. The raw data of the experiment showed readings that
varied as much as fourty times the error range. As I will show
elsewhere, certain experimenter bias and the lack of proper
temperature adjustments caused a published result well below the actual
signal detected. Niether the raw data nor the properly adjusted
and averaged data come close to being "within the error of
the experiment".
See For
Yourself
Unlike
those who give you their opinions and never proffer the evidence, I
provide for you here the original MMX
paper as
it was published in 1887. I will
provide information and analysis of the experiment to help you understand and analyse
it for yourself in the pages linked to from this
one.
The General
Concept
There are certain basic
assumptions that the experimenters had that greatly affected
the outcome and interpretation of the experiment. You must be
aware of all of these and their implications to fully understand the
experiment.
Assumptions:
1) Light propagates in a medium
called ether.(today called Aether) Light is not an entity itself nor does it have
particles any more than sound has particles. It is a disturbance of
this medum that occurs at a specific speed in relation to
that medium.
This was supported by nearly
100 years of science and was not in question at the
time.
2) Ether is a universal
reference frame that has specific coordinates. All of the bodies in
the universe move in relation to this one singular coordinate
system.
This is equivelent to
assuming the ocean has no currents and all the water in the
ocean is always in the exact same place. We could then use latitude
and longitude as the basic coordinate system and track the travel of
a boat through the water by measuring the speed and
direction at which the water passes by the boat.
3) The earth moves with respect
to the sun at a speed proven by astronomy and that speed is ~30
km/s.
The science behind this
assumption has been proven in multiple ways by
modern techniques as well.
4) The solar system as a
whole is travelling toward some place in the
galaxy
Purpose:
The purpose of the experiment was to try to determine the
direction and speed at which the solar system as a whole is moving
through the galaxy. It was the full expectation that a very
large effect would be detected since the component motions of the
earth and the solar system and the galaxy etc. could add up to a
very great velocity with respect to the universal reference frame.
This assumption of a stationary grid is quite presumptuous but it
was the dominant view of the time.
In short, the idea is that if the medium is moving with
respect to you, then you should be able to detect when you are
propagating a wave upstream because it should take longer to go the
same distance as cross stream from your perspective. These two
scientists had no doubt of the existence of Aether but instead were
determined to detect its motion using all the 19th century
pre-conceived notions of Aether.
Though the test did not come back as truly null it was not
what was expected. Many argue that the result was within the error of
the mechanism in all cases but this is very certainly not true in Dayton Miller's experiments and
likely not true in others when we see it in the light of all the
evidence. Unfortunately, the problem lies in the expectations of the
experiment. There were so many
assumptions about a medium that we know
almost nothing about. EM waves travel through matter; does this mean that
ether travels through matter too? Is matter perfectly transparent or does it
interact with ether to a
small extent?
Entrainment: One of the proposals
for why the ether wind was smaller than expected was that perhaps
matter entrained ether to a great extent. Perfectly opaque to ether,
it would drag it around. (You can visualize entrainment by
thinking of a dirty tennis ball submerged in a river. The particles
on the hairs further away from the surface will be washed away
quickly but all those hairs don't allow the water to run as quickly
across the surface of the ball deeper in. They entrain the water and
slow down the flow.)
While an interesting theory it seems unlikely for a number of
reasons such as how it would slow bodies moving through it and we do
not believe there is evidence of this. Additionally there were some
tests to try to entrain ether or detect its entrainment at this
level. These all came back false.
Dayton Miller did not fall directly into any particular camp
of thought when it came to the level of entrainment that occurred at
an object level but he did believe that encasing an experiment in a
metal housing and performing the experiment in a basement would
almost surely reduce the efficacy of the experiment. This was his
reasoning for the exceedingly small results of other
experimenters.
The newer school of thought leans toward a very small amount
of entrainment at an object level. This newest concept centers
around the fact that the ether wind detected by both the MMX and
Miller seemed to flow in a north/south direction which would
indicate that entrainment is generated by the magnetosphere or is
somehow closely involved in it. This is entirely contrary to the
direction originally expected for the wind as
well.
Wrongful
Expectations
The nature
of what should have been expected from the experiment is so complex
that I must explain it a piece at a time elsewhere. If you
understand the importance of this experiment and wish make your own
determination, it is imperative that you fully understand every part
of the experiment and can predict what should have
been expected yourself. I will provide as much understanding as
a can as simply as I can on this website but I will only give a
summary below. It is up to you to determine if you want to
understand the "why" behind it and read my fuller explanation
.
What should have been
expected? There are a few different thing they could have
and should have expected but lets talk about what they did expect
first.
Direction: First of all, if the wind is
caused by the earth's motion, then looking at the solar system from
a northern perspective, the Earth revolves around the sun in a
counter-clockwise direction. This means that at noon, the wind would
be coming from the west and at midnight the wind would be
coming from east. Now depending on your decision on whether or not
matter is transparent or opaque to the ether, the sixes would either
show a north/south wind or no wind at all because the wind would be
coming directly in from the top and not flowing along the path of
either of the legs.
Michelson expected
the Earth to be opaque and expected there to be a north/south wind at
the sixes. This is why his tests were performed at noon and six
o'clock.
Magnitude: If you
know what speed the Earth circles the sun from astronomical
observations, then it is a simple matter to determine the speed the
earth circles the sun and that is ~30km/s. This is exactly the speed
that is considered and expected by Michelson. However, one large
consideration seems to be overlooked and I like to call that the
"helicopter effect." (This is a consideration that the entire solar
system is moving.) When a helicopter flies forward, the blades
experience very different wind speeds on each side. If, for
instance, a helicopters blades circle at approx. fifty miles per
hour, and the craft is flying forward at fifty miles per hour, then
the wind speed at the tips of the blades will be 100 miles per hour
on one side and zero on the other. Combined with the fact that this test was performed for
only 3 days, it could have been very possible for it to show a null
result even with an existing ether.
Another very important
component of the test and determining magnitude is the behavior
of what they were looking at. They were looking at vertical lines
called fringes.
Without getting deep into the principles of interference, let it
suffice to say that what was expected was that as the device was
rotated, what should have been observed was those lines moving back
and forth. As the observed path was rotated into the wind,
the cross beam would "get ahead" of the other and the lines
would shift to one side. Then as the cross-ways beam shifted into
the path of the wind, it would fall behind the observed one and the
vertical lines would move to the other side. Obviously this means that there would not be some random
movement, but a steady slide back and forth and it would go back and
forth twice during one full rotation of the device. That is all the
way left then back to the right, then left and back to the right
again as the cross-shaped device was spun 360 degrees.
What
was expected is that the entire path a fringe/line would traverse would be measured
as .8 of the distance between one set of lines. That means that it
moved .4 of a space from the centerline left and .4 to the right
and hit each of those extremes twice during one full turn. Since
all that is sought is the difference between the two paths, it might
have been less confusing if the device was only turned one-eigth turn
so that all that was seen is both effected equally and then one leg into the
wind. This should show movement from the halfway point to the left
side or from halfway point moving to the right. The distance it
moved being only .4 of the width between the lines. Because
they preferred more data to eliminate experimental errors, they
turned the device round and round and averaged all of the equal
components. This is important because these
readings can be plotted out on a graph and should show very
sinewave-like pattern that would not appear if all that was
experienced was random error.
An unfortunate and little
understood part of this experiment is that though the expectation
was .4 of a fringe, a reading of .04 is
not a reading of one-tenth magnitude or
speed. This reading is something called a second order effect
and because of the squared nature of the math, a very small
difference in actual speed changes the size of the reading a very great
deal. While a speed of ~30km/s might equal a reading of .4, a
speed of ~10km/s would give a reading of only .04
Because of their lack of
understanding, most people repeat the mantra that the result was
one-tenth the size of the expectation and you should now see how
this statement, while true in a way, is a gross mis-representation of
the situation. Most significant though, is the fact that the
readings changed in the way that was expected instead of in a random
fashion. Even with many errors in experimental techniques, the
sine-wave like pattern can still be seen.
Experimental Errors
and the Experimenter Effect
Temperature:
The greatest errors in early interferometry were caused by
temperature changes. The expanding and contracting of the device,
while extraordinarily small, is enough to alter the results.
Michelson, while the inventor of the interferometer, did not have a great
deal of experience in operating his own device. Many later
experiments, especially the tens of thousands carried out by Dayton
Miller exposed the necessity of considering temperature fluctuation. It
was shown that, while the fluctuations that ocurred in metal
and concrete devices like these typically happened in a slow
and steady fashion, the effect was certainly evident. Miller
found that during the period of time for a
rotation of his device the temperature effect was linear and it could
not change from expanding to contracting during any single rotation
and in fact did not fluxuate in the rate of change
except under very great and unnatural temperature conditions. Miller's
interferometer rotated about once a minute while Michelson's rotated in approximately
six minutes. Michelson's is still a quite rapid rate
but perhaps not as reliable as Miller's.
What is
very strange about Michelson's data is that while an extra reading
of the beginning slot after each rotation was put in place, it
was not used to adjust the results. For instance, if there
are sixteen reading points and the reading is "10" for point
one at the beginning of the reading but when it turns all the way
around to reading point one again the reading is "15" then you can
see that the temperature caused a drift of five points during
the rotation time. Given that the change is constant and
unidirectional, the temperature error can very easily be eliminated
from the reading in a straight forward and intuitive manner.
Michelson, while the error is very obvious in his data, did not make any attempt
to correct it. Not only was the error left in but
readings with opposing errors of different degrees (one going up the other going
down) were averaged together. This lack of temperature consideration greatly reduced the
accuracy of his analysis. Thankfully some of his orginal data is left
for us to work with though they are averages of six
diffferent readings each that should have been corrected and are already
adulterated with possibly differeng temperature errors.
Micrometer VS
Estimation:
Another problem with this
experiment is the method for measurement Michelson used. To measure
the amount the firnges (lines) shifted, a micrometer was placed in
the field of view and adjusted to the center of a fringe at each
reading point and the reading on the micrometer was written down.
Miller, on the other hand, placed an immobile center mark in the
field of view and the reader estimated the distance the center
fringe was from the point in tenths of a fringe. At first
examination it seems as though the former method is superior to the
latter but this intuition is very far from the truth.
First
is the problem of touching the device to turn the screw of the
micrometer. The total difference being measured between the
path lengths of the light is only a couple
hundred nanometers. (A human hair can be as much as 100,000
nanometers thick) So touching the device even gently could slightly alter
the experiment.
Secondly, the physical size of the fringes
change with temperature as well as each time the device is
reset, whereas the measurement taken does not change. A single
fringe, regardless of its physical width, always represents the
same differential between path lengths. If a fringe shifts
one fringe width, the path length has changed the distance of one
wavelength of the tested light. This means that measuring fifty
thousandths(I'm assuming thousandsths for their micrometer) on one
reading is equal to one speed for the ether and fifty thousandsths on the next
reading is entirely another speed for the ether wind. He reported that
the fringe widths ranged from forty to sixty
in width and just used the average of fifty as his
determination. With the largest fringe width being
150% of the smallest fringe width, a large degree of innacuracy
is introduced. Averaging may subdue the error but it also subdues the magnitude
of the reading to an extent. The scale of the measurements
did not change but what they were measuring did (percentage of
a fringe)and then they were averaged together. Additionally, this means that
temperature drift within a single rotation of the device causes more than one
error type simultaneously and averaging measurements with these dual errors
could possibly cause a compounding adulteration of the
data.
Miller placed a mark in the
window of a device and used visual estimation in tenths of a
fringe so that averaging was "apples-to-apples"; it also kept the
device from being touched. Factoring out temperature drift on each
individual reading combined with the sheer massive volume of
readings Miller took to eliminate observer estimation error shows
how much Miller advanced the ether drift experiment's
technology.
  To the left is a picture of the MMX readings after a simple,
intuitive and straight-forward
linear ajdustment to reduce
temperature error
. This image is a graph
produced by Dayton Miller himself to visually exibit the easily
recognizable sine-wave characteristic observed in the
MMX.
The long wave of each set
represents the average of the full 360 degree rotation of the
interferometer on 3 different days with 6 rotations performed on
each of those days. As done by Michelson, the second shorter wave is
an average of the first half of the reading with the second half
because each 180 degrees are equivelent in determining fringe
displacement.
On the right, I have superimposed the actual readings on
the idealized variation of the readings that were expected of
the MM experiment. What is so remarkable is that in this
"null"experiment we do not have points arranged in some random
fashion even after averaging 18 rotations
, but instead we see the
readings rising and falling exactly as expected of the
wind.
While
Michelson's readings are a little sloppy because there were so few
readings taken, keep in mind when you read about Dayton
Miller that his work represents tens of thousands of
readings performed by teams of different individuals in
differing locations on differing devices over a great number of
years with thousands of hours put into far more up-to-date equipment
and far more stringent experimental controls and
considerations. Miller's 1933
paper is so
profound, and in-depth
it
takes many many readings to understand the
reasoning and conclusions, but upon seeing the data no
doubt can be left in the mind of one who has a
rudimentary grasp of interferometry, wave mecahnics, fluid dynamics
and relativity.
Conclusions
By the calculations we've established
here and on the expectations page,
the Michelson Morely experiment cannot be considered null or within
the error of the experiment. Instead we see readings indicating an
ether wind of ~10 Km/s with a variation of the reading that
coincides precisely with the
turning of the device between into the wind and
90 degrees to it. This complex behavior is exactly what should be expected
of the wind and not only has it not ever
been addressed or expained but cannot be explained in any logical fashion
that does not support ether.
Here is a table of MMX-like
experiments as they were interpretted at the time. Miller
later laments that in his 1904 report of results that they
mistakenly averaged sine-wave readings in apposing phase. A horrific
blunder that caused the reading to seem extremely small.
| Name | Year | Arm length of the
interferometer |
Fringe shift
expected | Fringe
shift reported |
| Michelson | 1881 | 1.2 | 0.04 | 0.02 |
| Michelson +
Morley | 1887 | 11.0 | 0.4 | 0.01 |
| Morley +
Miller | 1902-04 | 32.2 | 1.13 | 0.015 |
| Miller | 1921 | 32.0 | 1.12 | 0.08 |
| Miller | 1923-24 | 32.0 | 1.12 | 0.03 |
| Miller
(Sunlight) | 1924 | 32.0 | 1.12 | 0.014 |
| Tomascheck
(Starlight) | 1924 | 8.6 | 0.3 | 0.02 |
| Miller | 1925-26 | 32.0 | 1.12 | 0.088 |
| Kennedy (Mt.
Wilson) | 1926 | 2.0 | 0.07 | 0.002 |
| Ilingworth | 1927 | 2.0 | 0.07 | 0.0002 |
| Piccard +
Stahel(Mt.Rigi) | 1927 | 2.8 | 0.13 | 0.006 |
| Michelson et
al. | 1929 | 25.9 | 0.9 | 0.01 |
| Joos | 1930 | 21.0 | 0.75 | 0.002 |
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