# What is Michelson morley: Definition and 39 Discussions

The Michelson–Morley experiment was an attempt to detect the existence of the luminiferous aether, a supposed medium permeating space that was thought to be the carrier of light waves. The experiment was performed between April and July 1887 by American physicists Albert A. Michelson and Edward W. Morley at what is now Case Western Reserve University in Cleveland, Ohio, and published in November of the same year.The experiment compared the speed of light in perpendicular directions in an attempt to detect the relative motion of matter through the stationary luminiferous aether ("aether wind"). The result was negative, in that Michelson and Morley found no significant difference between the speed of light in the direction of movement through the presumed aether, and the speed at right angles. This result is generally considered to be the first strong evidence against the then-prevalent aether theory, as well as initiating a line of research that eventually led to special relativity, which rules out a stationary aether. Of this experiment, Einstein wrote, "If the Michelson–Morley experiment had not brought us into serious embarrassment, no one would have regarded the relativity theory as a (halfway) redemption."Michelson–Morley type experiments have been repeated many times with steadily increasing sensitivity. These include experiments from 1902 to 1905, and a series of experiments in the 1920s. More recently, in 2009, optical resonator experiments confirmed the absence of any aether wind at the 10−17 level. Together with the Ives–Stilwell and Kennedy–Thorndike experiments, Michelson–Morley type experiments form one of the fundamental tests of special relativity theory.

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1. ### B How are 'fringe shifts' in the Michelson-Morley experiment calculated?

Ok for the interferometer let the arm lengths be ##L##, speed of light relative to the aether be ##c## and the speed of the setup relative to the aether be ##v##. By calculation you can show that the distance between the two 'heads' of the beams of light is ##\frac{v^2L}{c^2}##, and using the...
2. ### I Michelson–Morley experiment and the velocity of the ether wind

How was it justified before conducting the MICHELSON–MORLEY experiment to assume that the sun was at rest with respect to the ether? Also, was the ether assumed to have the same velocity with respect to the Earth throughout space at one instant in time, or like wind, with different velocities at...
3. ### I Michelson-Morley: Errors in Calculations?

I would like to know the opinions on the paper that I saw about Michelson-Morley experiment. Michelson-Morley experiment was done in 1887 and had an impact on the future direction of physics. It is taught in schools as an experiment that proves the non-existence of the aether and proves the...
4. ### I Violation of Special Relativity Principle?

From the michelson-morley experiment, if a clock were to measure the time period of light hitting the mirror and returning back, it would be 2L/c, where L is the distance between the laser nd the mirror. For a moving observer, the time period would have a factor of *gamma*, the boost factor...
5. ### B Questions on the Michelson Morley Experiment

I've heard claims the Michelson Morley experiment proves light moves at the same speed in all reference frames. However, after looking through the experimental setup, I do not see how they can make this claim. The entire experiment, from my view, was conducted in Earth's reference frame. His...
6. ### I Why do we need a theory to replace the Galilian composition of velocities?

In Michelson Morley experiment we use a moving mirror to reflect light and then we find out that light moves with c regardless of the speed of the mirror. My question is why do we need a theory to replace the galilian composition of velocities?i mean this can be explained by saying that...
7. ### I Learn Michelson Morley Exp: Best Books Explaining Light's C Speed

I want a book that explains everything about Michelson Morley experiment. The one that says light moves with c regardless of the speed of the source and also the one that says light appeared to move with C for all observers.
8. ### I Michelson Morley experiment: relativistic explanation

I don't uderstand how, using special relativity theory (time dilatation and length contraction), one can explain why in the Michelson interferometer there is no delay between the two rays in the reference frame where the interferometer is moving. Consider the picture ##2.## Setting...
9. ### I How Does the Michelson-Morley Experiment Challenge Classical Physics?

Relativity, Resnick Here, for calculating t2 , w.r.t. ether frame, light is moving along the triangular path as shown in Fig. 1.7 with speed c. w.r.t. interferometer frame, light is moving along the straight path with speed c##\hat y## - v ##\hat x## while going up and with speed -c##\hat y##...
10. ### B Evolution of Principles: Michelson-Morley, Lorentz & Einstein

Hi forum, I followed through Feynamn's derivation to show the different times taken for light by the parallel and perpendicular paths of the Michelson Morley apparatus. He showed that it took longer for light to go to the far mirror and back if it were parallel to the direction the whole...
11. ### I Michelson Morley Experiment Light Source

My question is that in Michelson Morley experiment, how they produced the light? what was the light source and has anyone used sunlight as a source yet to re-confirm that experiment? I am interested in sunlight as a source of light due to certain reason... Please if you know kindly mention the...
12. ### B Why Use a Photodetector in Interferometry?

Hello! I am trying an interferometry experiment using the Michelson Morley experiment. I managed to obtain the interference pattern on a screen, but I want to use an photodetector and I am not sure what should I obtain. As I know, the oscilloscope shows the intensity of the light, so if I modify...
13. ### I Did the Michelson Morley Experiment Prove the Existence of Ether?

By measuring the speed of the light beams through the inferometer michelson morley tried to explain the existence of ether. This was done by measuring light beams's speed. The beams were in different direction. Did they want to say that the beam in the direction of the movement of the Earth...
14. ### A How Does Arm Length Affect Doppler Shift Measurement?

full screen (high res) http://images.tinypic.pl/i/00765/8g7j8biccn4d.jpg Em Wave = LIGHT Em Wave = RadioEquator Source------L---------SensorHow big L we need use to register Doppler ? I wan to measure 360/24h speed Big Question ?! single arm we have Doppler (RED ) [ more long arm --->...
15. ### I Why is the medium in the Michelson Morley experiment ignored

Normally in explaining the aether model of light it is said that all waves need a medium, so just like sound uses air, light uses the aether. To my understanding sound can travel through gas, liquid and solids just fine without air being partially entrained in the materials. Sound does not use...
16. ### Puzzle of negative result of Michelson Morley experiment

HI all How can Michelson itself predicted contraction of length and Einstein about constancy of light from negative result of MM experiment. forget about existence of ether, light speed always same in moving frame of reference and importantly in any direction so how can one except shift in...
17. ### Understanding the Path Difference in Michelson Morley Experiment

I'm a little confused about this. I know how to derive the expression t≈lv2/c3 for the time difference between the arrival of the two beams due to the presence of an ether, with the Earth moving at speed v through the ether, and l the distance between the beam splitter and each mirror. This can...
18. ### Doubt in Michelson Morley experiment

Hi All, I studied about Michelson Morley experiment in my graduation in the compulsory Physics paper. I had Computer Science major(not a Physics guy:frown:), anyways this question came in my mind during my graduation time and may be because of my misinterpretation however couple of days ago...
19. ### Question about Michelson Morley experiment

Hi everyone. I'd like you to help me make sense of a question I found about the Michelson Morley experiment. This is it: "Explain how and why the uncollimated light rays form interference fringes? Can you say what would happen if the rays were collimated?" Does this question even make...
20. ### Why Does Rotating the Michelson-Morley Apparatus Change the Time Delay?

I am having difficulty understanding why when the apparatus in the figure on page 448 (http://web.physics.ucsb.edu/~phys22/K%20and%20K%20Sections/KK_Chapter11.pdf ) is rotated 90 degrees the time delay is twice what it was before. When I think about I immediately think it would be the same since...
21. ### Why Does Rotating the Michelson-Morley Apparatus Alter the Time Delay?

Homework Statement It isn't really a homework problem rather http://spiff.rit.edu/classes/phys200/lectures/mm_results/mm_results.html If you search " After they rotated the device by 90 degrees, the arm which was sideways to the ether would now be going with-and-against the wind...
22. ### Thermal expansion (and the Michelson Morley experiment)

Homework Statement (B) http://imgur.com/VL4aG although I showed the rest of the problem for context if needed Homework Equations ΔL=αLΔT The Attempt at a Solution I'm a little confused by the wording of the problem. When we find the shift in ΔN, are we actually finding Δ(ΔN)...
23. ### Michelson Morley experiment and heliocentrism

Hello, I just heard a guy talking about the Michelson-Morley experiment as evidence that the Earth is still. It is true that the MM experiment basically showed that the Earth was at rest with respect to "the ether" (but we know that the Earth moves around the sun, so the notion of ether...
24. ### Michelson Morley Experiment for Arbitrary Angle

Homework Statement The ether wind theory of the Michelson-Morley experiment is discussed in the text for the special case where the arms of the interferometer are parallel and perpendicular to the wind. Consider the general case for an angular setting θ. Prove that, for equal arms of length L...
25. ### Michelson Morley Exp. Phase Difference Question

Homework Statement The problem I am misunderstanding begins with a reference to a previous problem and example. Let me begin to ask my question by showing my work for the previous problem and describe the example in reference. (reference problem) - Ch.1, #13. Consider a reference frame...
26. ### Question on Michelson Morley experiment and length contraction

I'm a lay person who is interested in developing a better understanding of science in general, as well as specific theories. I'm just wondering if someone would be able to help me understand how Length contraction explains the null set of the Michelson Morley experiment? Hopefully this...
27. ### Advances in michelson morley interferometer

hello, i am curious to know more about advancements that has happened to the M-m experiment, i am studying relativity and recently saw a http://youtu.be/7T0d7o8X2-E" of a modified interferometer. anyone knows a book/blog/file that talks purely about this. thanks.
28. ### What was the motive of michelson morley experiment

what was the real motive of MM experiment to measure the speed of light or to measure the orbital speed (or speed of ether) of Earth with respect to stationary ether? plss anyone reply
29. ### Michelson morley exp and rotating 90 degrees

Homework Statement Ok, I was able to figure out the difference in time for the michelson morley experiment and hence the fringe shift is B^2*L/wavelength. What i can't understand is why after shifting the experiment 90 degrees the fringe shift is supposed to be different. the one...
30. ### Does General Relativity Affect Vertical and Horizontal Light Beam Speeds?

I think General Relativity would argue that the light traveling vertically, shown in the diagram by the blue track, would be faster than the beam traveling an equal distance horizontally in the predominantly stronger gravitational field. We are assuming no atmosphere. Is this correct or could...
31. ### Understanding the Impact of Michelson Morley Experiment on Modern Science

Could someone please explain to me the significance of the results of the michelson morley experiment? What is the explanation of how those results could happen and how they fit in with current theory? Has the experiment been repeated in space away from the Earth's gravity field?
32. ### Relative velocity and Michelson Morley experiment

Homework Statement I was reading up on an experiment,The Michelson Morley experiment, in preparation for Physics lab. Then there was this problem. The textbook stated that the velocity of the light ray that was traveling perpendicularly to the ether wind was \root{c^2-v^2}. Shouldn't it have...
33. ### Calculating Micrometer Reading Change for 50 Fringes at λ = 550 nm

Homework Statement Suppose the calibration constant of your spectrometer is 0.5, and suppose the wavelength of the light is λ = 550 nm. How much does the micrometer reading change during the movement of M2 that generates the passage of 50 fringes? Homework Equations possibly delta(l)=...
34. ### Null result of the michelson morley experiment

Homework Statement Show that the null effect of the michelson morley experiment can be accounted for if the interferometer arm parallel to motion is shortened by a factor of (1-v^2/c^2)^.5 Homework Equations V(earth)=29.8 km/s , fringe in MM experiment is .4 ; gamma =sqrt(1-v^2/c^2) The...
35. ### No width contraction in Michelson Morley Experiment, why?

Based on the Michelson Morley experiment, Lorentz proposed already length contraction as an explanation of the negative outcome of the experiment. a) Did he also propose time dilation? b) How is width contraction ruled out: is that a necessary conclusion of the Michelson Morley experiment or...
36. ### Why Does the Michelson-Morley Experiment Use T1-T2 Even After Rotation?

Pl. guide me for the doubts that i have in MME In this experiment suppose L1 = L2 Then in this case will there be in any change in time difference T1-T2 calculated before and after rotation of the apparatus? Another query is first we find T1-T2 now if first path is parallel to ether wind...
37. ### Why is light traveling through the ether not just at speed c?

I've just started reading the dustiest book on relativity i could find at the local library and like most others I've seen it includes the Michelson Morley experiment. I just need a bit of clarification on the formulae they use. The equations t1=2l/(c^2 - v^2)^1/2 and t2=2lc/c^2 - v^2...
38. ### Michelson Morley and Paul Marmet

Retired Canadian physicist, Paul Marmet, has published a number of 'heretical' papers that question some fundamental principles of modern (non-Newtonian) physics. see: http://www.Newtonphysics.on.ca/ I have glanced through his paper that tries to explain errors in the math used in the...
39. ### Does the Earth's movement towards the sun affect the speed of light?

I thought the idea was that light should move faster coming towards the Earth than moving away but that it was found that the two speeds were the same; but isn't the Earth moving towards something adding to its rate just as the Earth moving away from something adds to the rate at which it is...