physics gurus: aether experiment help (1 Viewer)

[Abtari]

just one thing guys that i am a bit dazed about.

can you guys let me know if what i have written here is correct? I am not sure if my account of michelson-morley expt is correct or not, especially the reason for interposing the two rays. Thanks heaps!

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"They supposed aether wind travelled against the direction of light as it emerged from the source.
Thus one would find or at least expect to find that the two reflected light beams are out of phase. They did (hooray!). However, this could also be due to minor length differences of the arms and/or mirrors not positioned with exact perpendicularity. So is it because of the aether or the error?

They interposed the two rays by rotating the interferometer by 90 degrees. Now, if there is no aether wind, then we would see the same interference pattern (because the rays will still be out of phase by the same margin). If there is an aether wind, like there was in the first part of the experiment, then there will be a change from original pattern because light rays are exposed to different conditions on their path despite the same pathlengths. There found no change - the same pattern. A null result. No aether existed. The supposed pattern showing light rays our of phase (before interposing) was due to experimental inconsistency."

 

[Ghost1788]

Ok i not sure about the inaccuracies because my understanding is that the two beams of light arrived in phase, however if it is as you said then i would blame it on the error and not on the 'aether wind'.

All that you need to know for the HSC is that the michelson and morley experiment set out to prove the existance of an aether wind (which was produced by the earth passing through the aether) however this experiment proved the non-existance of an aether wind because both beams/rays of light where found to be in phase at the end.

however if u really want to devulge your self into this topic i refer you to http://en.wikipedia.org/wiki/Michelson-Morley_experiment
which should clear up any problems you have....

Ghost :uhhuh:

EDIT: oh inaccuracies refer to the link yups if still in doubt take a look at the physics page about this experiment at http://hsc.csu.edu.au/

 

[Abtari]

PHY: half yearly tomoz - MM expt help

Ok i not sure about the inaccuracies because my understanding is that the two beams of light arrived in phase, however if it is as you said then i would blame it on the error and not on the 'aether wind'.

All that you need to know for the HSC is that the michelson and morley experiment set out to prove the existance of an aether wind (which was produced by the earth passing through the aether) however this experiment proved the non-existance of an aether wind because both beams/rays of light where found to be in phase at the end.

Ghost :uhhuh:

EDIT: oh inaccuracies refer to the link yups if still in doubt take a look at the physics page about this experiment at http://hsc.csu.edu.au/

but then if it is as you say, that both beams/rays of light were found to be in phase at the end, IN BOTH CASES then what was the point of trying to interpose the two rays by 90 degrees? why did they rotate the apparatus in the first place? that is what i am confused about (ultimately). arrgh! have half yearlies tomoz...

 

[richz]

but then if it is as you say, that both beams/rays of light were found to be in phase at the end, IN BOTH CASES then what was the point of trying to interpose the two rays by 90 degrees? why did they rotate the apparatus in the first place? that is what i am confused about (ultimately). arrgh! have half yearlies tomoz...

well if u rotated it one would go across the wind and the other go with it but go against it when it comes back. Change in distance means change in time..

 

[Abtari]

well if u rotated it one would go across the wind and the other go with it but go against it when it comes back. Change in distance means change in time..

im not quite sure what uve said. ive written what i think is correct using your wording. this is my reply to your post: "even if you didn't rotate it, one would go across the wind and the other would go with it but go against it when it comes back."

what do you think? any ideas about why they rotated it then? thanks.

 

[Xayma]

im not quite sure what uve said. ive written what i think is correct using your wording. this is my reply to your post: "even if you didn't rotate it, one would go across the wind and the other would go with it but go against it when it comes back."

what do you think? any ideas about why they rotated it then? thanks.

You cant measure the distances exactly, the wavelength is too small.

When rotated however, the direction relative to the aether would have changed which would result in a change in speed and hence a change in wavelength, v=fλ, this would therefore change the interference pattern.

 

[Abtari]

Please Proofread: Aether Expt

You cant measure the distances exactly, the wavelength is too small.

When rotated however, the direction relative to the aether would have changed which would result in a change in speed and hence a change in wavelength, v=fλ, this would therefore change the interference pattern.

ok let me get this straight. pls correct me if im wrong:

1) they sent a light through a half-silvered mirror. they got an interference pattern of the two light rays. they noted the interference pattern and saw that the two incoming rays were OUT OF PHASE.

2) however this was NOT enough to prove the existence of an aether wind.

3) thus, they rotated the whole apparatus through 90 degrees.

4) their method of attack: having rotated the apparatus by x degrees, a SIZEABLE change in the interference pattern would indicate the presence of an aether wind. a LITTLE/NO change would indicate the absence of an aether wind.

5) their result: there wasn't any SIZEABLE change in the inteference pattern. hence no aether.

any suggestions on my interpretation of this concept would be much appreciated.
thanks heaps.

 

[Jago]

there wasn't any change in the interference pattern

 

[Abtari]

there wasn't any change in the interference pattern

i.e. when they rotated the apparatus through 90 degrees rite?

 

[lfc_reds2003]

yes exactly

 

[velox]

yep thats correct. Thus showing that the there was no aether because....

someone complete the sentence for me, ive forgotten

 

[Abtari]

no change in the interference pattern when rotated through 90 degrees had to mean that there was no aether because if there was a change in the pattern:

- that would have meant that the two light rays would have been exposed to DIFFERENT CONDITIONS on their path (cant think of another reason why it would be different, can u??)

- DIFFERENT CONDITIONS meaning a ray would have been exposed to the aether wind in a different manner to the other ray.

- hence the aether.

BUT SINCE THIS DIDN'T HAPPEN, hence no aether.

is this rite ppls? am i completing velox's blank right???

 

[speed2]

i thought the experiments null result meant that they couldnt detect the aether wind not that there was NO aether. Just because they didnt detect it didnt mean that there was no aether.

 

[velox]

Yep abtari that completed it. "wind" was they keyword. I dont think we should over analyse this dot point.

 

[Abtari]

i thought the experiments null result meant that they couldnt detect the aether wind not that there was NO aether. Just because they didnt detect it didnt mean that there was no aether.

yes they couldn't detect the aether, which meant they couldn't prove it existed --> which meant what? they had to assume, as good scientists, that aether DID NOT exist.

i second what velox said --> let's not entangle ourselves in semantics.