Wikipedia:Peer review/Michelson–Morley experiment/archive1

Michelson–Morley experiment[edit]

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This peer review discussion has been closed.
I've listed this article for peer review because it failed this GA review due to prose issues. After this peer review, the article should be nominated again for GA.

Thanks, D.H (talk) 11:18, 17 June 2012 (UTC)[reply]

Comments from RJH:

The lead doesn't summarize all important aspects of the article. See WP:LEAD.
Simple, inline math expressions such as $10^{-17}$ and $\lesssim 10^{-17}$ stand out prominently from the text, but it would be preferable that they didn't. You can instead use HTML/unicode characters to write 10^–17 or ≲10^–17.
The article is fairly weak in the number of citations. For example, I'd expect at least one cite per paragraph in the "Measuring aether" section.
"...producing a pattern of constructive and destructive interference based on the spent time to transit the arms": I understand what this is trying to say, but the wording is a little unclear. I believe the pattern depends on the difference in the travel times, rather than the net time. But it also needs to clarify why there is a transverse pattern since the net time difference is about the same. I.e. it needs to go into some detail about wavelengths of light and incremental differences in travel distances based upon the angle. This explanation seems important to the reader's understanding of the topic, so you could probably add an extra paragraph here and perhaps an illustration.

Regards, RJH (talk) 16:30, 22 June 2012 (UTC)[reply]

Thanks for the comments! D.H and I will work on those points. Stigmatella aurantiaca (talk) 20:37, 22 June 2012 (UTC)[reply]

Yes, thanks for the review. I'll add some additional citations. --D.H (talk) 08:14, 23 June 2012 (UTC)[reply]

D.H - I'll try working on a couple of illustrations. One will be a conventional one based on the Pythagorean theorem, the other will be an animation. We'll see what works. Stigmatella aurantiaca (talk) 04:09, 23 June 2012 (UTC)[reply]

That would be great! --D.H (talk) 08:14, 23 June 2012 (UTC)[reply]

D.H -

I think RJH wanted a figure something like this one. However, I'm not at all sure this image belongs in the Michelson–Morley experiment article. It is something that would fit in Michelson interferometer or Interferometry. However, if you think it fits in Michelson–Morley experiment, by all means add it!

(a) If mirror M₁ and the reflected image M'₂ are parallel but separated by a finite distance, the two reflected sources S'₁ and S'₂ will be centered on the normal to the mirrors, and the interference fringes will be circles. (b) If M₁ and M'₂ are angled with respect to each other, S'₁ and S'₂ will be separated from each other. The interference fringes in general will be hyperbolas, but if M₁ and M'₂ overlap, the fringes near the axis will be perceived as a set of equally spaced straight lines. If S is an extended source rather than a point source as illustrated, the fringes of (a) must be observed with a telescope set at infinity, while the fringes of (b) will be localized on the mirrors.

I'm still working on the animation, by the way. I'm writing a computer program to generate the images, which will be exported to bitmaps that I will then assemble into a GIF. The animation should be cute, but not necessarily something that belongs in the article. Stigmatella aurantiaca (talk) 10:35, 26 June 2012 (UTC)[reply]

That's another excellent animation! But I agree with you that Michelson interferometer might be the better article for describing such details of this interferometer. --D.H (talk) 11:15, 26 June 2012 (UTC)[reply]

RJHall -

I added Figure 4 to the article, but wasn't sure if that was what you meant, or a figure like the one I've included on this page. Comments? Stigmatella aurantiaca (talk) 11:11, 26 June 2012 (UTC)[reply]

Animation

Animated demonstration of the origin of the expected differential phase shift between light traveling the longitudinal *versus* the transverse arms of the Michelson–Morley apparatus

Well, what do you think? Personally, I think the animation is a bit silly, but RJH did state that "[the article] needs to go into some detail about wavelengths of light and incremental differences in travel distances based upon the angle. This explanation seems important to the reader's understanding of the topic, so you could probably add an extra paragraph here and perhaps an illustration." Even if we never use it, I got to experiment with some tools in C# which I hadn't used before, so it definitely wasn't a waste of my time. It was a fun way to spend a few hours this 4^th of July. Stigmatella aurantiaca (talk) 04:35, 5 July 2012 (UTC)[reply]

One way of using the animation might be through a link: "For an animated demonstration explaining the origin of the differential phase shift between light traveling the longitudinal versus the transverse arms of the Michelson–Morley apparatus, click here." That way the main body of the article retains its encyclopedic tone, while those who like cartoons can watch this one. Stigmatella aurantiaca (talk) 04:54, 5 July 2012 (UTC)[reply]

One of my pet peeves on Wikipedia are the many pretty, striking, or even beautiful illustrations that are not well integrated with the text and which, after you get through admiring their aesthetic qualities, leaves you wondering what really was being illustrated. Case in point is a Featured Picture that was picture of the day on the English Wikipedia for October 16, 2006: File:Lorentz transform of world line.gif. Beautiful? Yes. Meaningful? Well, I'm reasonably familiar with the subject (very far from being in the same class as D.H, though) but when I look at this picture, I wonder what it is trying to say. I much prefer the simple, straightforward drawings in the article Minkowski diagram.

I'm not against animation per se. In fact I've created others in the past, for instance File:White light interferometric microscope.gif. But animation has to be for a good reason.

What I am trying to say is, if you think it should be displayed in the article, well then, great! But if you think it might best be referred to through a link, well, that's sort of my own feeling. Stigmatella aurantiaca (talk) 11:37, 5 July 2012 (UTC)[reply]

I wonder if perhaps a simple illustration of a double-slit experiment would serve? Mathematically it is the same effect in the sense that a single beam is being used to generate two sources, which then recombine to produce an interference pattern based upon the difference in their path lengths. You could then place the animation directly below to illustrate the comparable behavior of the Michelson-Morley experiment. Regards, RJH (talk) 14:52, 5 July 2012 (UTC)[reply]

Of course, the equivalence to the double slit is the point of my earlier illustration on this page, which now appears on Michelson interferometer and on Interferometry, but which D.H and I decided probably didn't belong in Michelson–Morley experiment. The articles have different goals: (1) explaining how the Michelson interferometer works, and (2) explaining about the experiment itself and its importance in the history of physics. Trying to do too much in a single article gets us into problems of balance and focus. We could easily double the size of the article just on the 1887 experiment alone. There's lots of fascinating material on how the interferometer pushed the limits of the available technology, human interest material on Michelson, and so on and so forth which we didn't cover and which don't appear even in Michelson's biography on Wikipedia. It's tough picking and choosing what should be the correct things to present in an article, alas! Stigmatella aurantiaca (talk) 15:34, 5 July 2012 (UTC)[reply]

As you wish then. Regards, RJH (talk) 15:57, 5 July 2012 (UTC)[reply]

I decided to insert the animation and let D.H decide whether it serves a real purpose or not. After all, he's a much more important contributor to the article than I am. Stigmatella aurantiaca (talk) 02:12, 6 July 2012 (UTC)[reply]

I first misunderstood the image. But now I see that it is correct, thanks. --D.H (talk) 11:33, 6 July 2012 (UTC)[reply]

PS: Animated images like this look quite good in the article. --D.H (talk) 11:51, 6 July 2012 (UTC)[reply]

Addendum from RJH: Here are some additional comments:

What does "...wind at the 10⁻¹⁷ level" mean?
"Many other experiments ... have been conducted as well as tests of special relativity": Is this sentence trying to say "Many other confirming experiments"? It could use some clarification.
What does "...effects of first order..." or "...measuring second order effects..." mean? It is unclear from the context.

Regards, RJH (talk) 17:24, 13 July 2012 (UTC)[reply]