Michelson Morley experiment (1 Viewer)

[Elise8842]

Hi

Could anyone please explain to me what's the effect of rotating the interferometer by 90 degrees?

Some books say "this will change the speed of the aether wind along th e direction of the arms of the interferometer " but I don't really understand hat it means... Does it mean the direction of the aether wind relative to one of the arms is thus changed?


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[QZP]

Initially: say beam A was affected by the aether wind and beam B (perpendicular to aether wind) was not. This will produce a certain interference pattern.
After apparatus rotated 90 deg: beam A is now unaffected by aether wind whereas B now is (due to their directions relative to the aether wind being changed). This will produce a different interference pattern.

Draw a diagram if you can't see it. Another way of saying this is the aether wind is rotated 90deg relative to the apparatus.

Let me know if you still don't get it.

 

[anthony_wheels]

http://en.wikipedia.org/wiki/File:MichelsonMorleyAnimationDE.gif
The one on the right was what M&M thought the light would do, so by rotating the apparatus the interference pattern created by the 'recombining' of the light beams would be different to the first. As we know there was no different interference pattern, which lead to Einstein's theory of SR in regards to the constancy of the speed of light for all frames of reference.

 

[strawberrye]

http://en.wikipedia.org/wiki/File:MichelsonMorleyAnimationDE.gif
The one on the right was what M&M thought the light would do, so by rotating the apparatus the interference pattern created by the 'recombining' of the light beams would be different to the first. As we know there was no different interference pattern, which lead to Einstein's theory of SR in regards to the constancy of the speed of light for all frames of reference.

It is very important to understand the MM experiment did not lead to einsteins's theory of special relativity, Einstein independently developed the theorem, rather, the experiment results offered proof for einsteins's theory of special relativity. This distinction is important.

 

[Squar3root]

also important to note that the experiment was suspended in liquid mercury for easy and accurate 90 degree rotation

 

[xGhanem]

also important to note that the experiment was suspended in liquid mercury for easy and accurate 90 degree rotation

Why would that be important? Isn't it just sufficient enough to explain that the experiment was able to rotate 90 degress, and the reason it was rotated?

 

[Squar3root]

Why would that be important? Isn't it just sufficient enough to explain that the experiment was able to rotate 90 degress, and the reason it was rotated?

this separates the good students from the high achieving students. these little details and facts impress the marker = more marks

 

[xGhanem]

this separates the good students from the high achieving students. these little details and facts impress the marker = more marks

Oh, I see.

 

[Squar3root]

Oh, I see.

have a look at some of the exemplar responses from past hsc student's papers. you will be immediately able to see (if you can read their writing) how they answer questions

 

[QZP]

this separates the good students from the high achieving students. these little details and facts impress the marker = more marks

if anything, markers think you can't read the bloody question and just flop around

 

[xGhanem]

have a look at some of the exemplar responses from past hsc student's papers. you will be immediately able to see (if you can read their writing) how they answer questions

Where can I see them???

Sent from my GT-I9300 using Tapatalk

 

[Squar3root]

if anything, markers think you can't read the bloody question and just flop around

yeah, i had bad hand writing and my english teacher was like *flip table* and she couldn't understand it so she made me type it out. (it was good for me because i didn't really do it properly so when i typed it out i could edit all my mistakes huehuehue

but really the marker will make a genuine attempt to read the students answers or will pass it on to a senior marker for them to try to understand. its not like if the marker doesn't see size 12 times new roman font as the typeface of your hand writing they're gonna be like fuck this shit, where did i screw up and become a teacher. of in the rare circumstance the student writes in like hebrew or hieroglyphics then they are gonna be like this dyslexic nigga deserves a zero. but they do make an attempt

Where can I see them???

Sent from my GT-I9300 using Tapatalk

you can see some old papers here: http://arc.boardofstudies.nsw.edu.au/go/hsc/std-packs/

or you can buy it from bos here: http://www.boardofstudies.nsw.edu.au/manuals/hsc-exam-workbooks.html

or see if your library has a copy

 

[Elise8842]

Initially: say beam A was affected by the aether wind and beam B (perpendicular to aether wind) was not. This will produce a certain interference pattern.
After apparatus rotated 90 deg: beam A is now unaffected by aether wind whereas B now is (due to their directions relative to the aether wind being changed). This will produce a different interference pattern.

Draw a diagram if you can't see it. Another way of saying this is the aether wind is rotated 90deg relative to the apparatus.

Let me know if you still don't get it.

Since beam A and beam B are identical, if the aether wind was to affect them from either direction, a same interference pattern would be observed wouldn't it? That is, it's the Beam A or Beam B get affected by the aether wind doesn't really matter? Sorry, I'm stuck here


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[QZP]

Since beam A and beam B are identical, if the aether wind was to affect them from either direction, a same interference pattern would be observed wouldn't it? That is, it's the Beam A or Beam B get affected by the aether wind doesn't really matter? Sorry, I'm stuck here


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All you need to know is that it will produce a shifted interference pattern (after rotating 90 deg). You're right in the sense that the same interference pattern is produced however this new interference pattern looks shifted.

If you want to understand why, then I suggest looking into Thomas Young's Double Slit experiment. Basically, when the two light beams re-join at the half silvered mirror, there is destructive interference and constructive interference in different areas of the light wave. This causes dark and light fringes (some lines on the screen are dark, other lines are bright), forming the interference pattern. After rotating 90deg, these fringes seem to have 'shifted' since at first A and not B was affected by aether wind, and then B and not A was affected by aether wind after rotating (the degree of 'effect' on the light waves by the aether wind is the same in both cases that's why these fringes shift and not completely form a new pattern).

 

[Elise8842]

All you need to know is that it will produce a shifted interference pattern (after rotating 90 deg). You're right in the sense that the same interference pattern is produced however this new interference pattern looks shifted.

If you want to understand why, then I suggest looking into Thomas Young's Double Slit experiment. Basically, when the two light beams re-join at the half silvered mirror, there is destructive interference and constructive interference in different areas of the light wave. This causes dark and light fringes (some lines on the screen are dark, other lines are bright), forming the interference pattern. After rotating 90deg, these fringes seem to have 'shifted' since at first A and not B was affected by aether wind, and then B and not A was affected by aether wind after rotating (the degree of 'effect' on the light waves by the aether wind is the same in both cases that's why these fringes shift and not completely form a new pattern).

Ahh that's the reason why... Thank you so much!


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