Has the Michelson - Morley experiment ever been replicated in a vacuum?

May 19, 2011 9:52 AM

Has the Michelson - Morley experiment ever been replicated in a vacuum?

Has the Michelson - Morley experiment ever been replicated in a vacuum? I keep reading descriptions of it but not one of them mentions if this was done in a vacuum. This is strange since the speed of light depends on what medium it travels through (which is what causes light refraction). Thus, wouldn't any experiment trying to prove or disprove the existence of some underlying medium that pervades all of space need to be performed in a location devoid of any other medium (air in this case)? I know this experiment has been replicated many times but I can't find any specific instances of it being performed in a vacuum. Also, if it has been performed in a vacuum, have vertical angles been tested as well?

Thanks!

posted by enamon to science & nature (12 answers total)

have vertical angles been tested as well?

The original experiment was run all times of the day, throughout the entire year. Note that what's "horizontal" at one time is "vertical" six hours later.
posted by Chocolate Pickle at 10:02 AM on May 19, 2011

Chocolate Pickle:

Not in relation to gravity.
posted by enamon at 10:06 AM on May 19, 2011

Has the Michelson - Morley experiment ever been replicated in a vacuum

Yes, repeatedly. This article and its first 5 references are a place to start.
posted by brainmouse at 10:07 AM on May 19, 2011 [2 favorites]

Thus, wouldn't any experiment trying to prove or disprove the existence of some underlying medium that pervades all of space need to be performed in a location devoid of any other medium (air in this case)?

The non-existence of the aether has been disproved in more than one way. No one relies on that experiment.
posted by empath at 10:07 AM on May 19, 2011

Thus, wouldn't any experiment trying to prove or disprove the existence of some underlying medium that pervades all of space need to be performed in a location devoid of any other medium (air in this case)?

No, because in the way that the experiment was set up, air would be a negligible contribution to the difference between the time of return of the parallel and perpendicular beams, relative to the motion through the "ether wind" generated by the movement of the earth.
posted by kagredon at 10:15 AM on May 19, 2011

If the movement or stillness of the air were what produced the M-M result, then you would expect to see light more strongly affected by wind. Also, how would we manage to see stars?

The ether theory that tried to incorporate the M-M result was that the ether was somehow bound to, or dragged by, the Earth, so that the ether was always stationary relative to the experiment. However, this predicted aberrations in the apparent locations of stars which weren't observed. I think there might have been another variation or two trying to save ether theory before people gave up on it.
posted by hattifattener at 11:36 AM on May 19, 2011

One also has to remember that they considered aether to be: something that pervaded space and that earth was sloshing through it like a boat in the ocean. Some thought aether had currents, other didn't. Some of the Aether hypothesis tried to take into account that light's speed changed in different mediums. Aether existed in their minds as a addition to the matter we interact with so you could compensate for how it behaved in different materials. (See Aether Drag Hypothesis)
On Preview: Pretty much with hattifattener said. It doesn't matter how you reasoned about evidence. People came up with a lot of theories on how aether behaved to try to get the theory to work.
posted by roguewraith at 11:46 AM on May 19, 2011

> The non-existence of the aether has been disproved in more than one way.

Woo hoo! Double negatives for the win! My aether flyer design can still work!

And, apropos of nothing, Albert Michelson spent much time as a youth in Virginia City, Nevada, after his parents emigrated from Prussia in the 1850s. This was too much coincidence for the producers of Bonanza to ignore, and Michelson is, as far as I know, the only Nobel winning scientist to appear as a character on the show. (Hoss gets caught up in helping the young Michelson with his early work to determine the speed of light.)
posted by Naberius at 12:19 PM on May 19, 2011 [3 favorites]

Woo hoo! Double negatives for the win! My aether flyer design can still work!

Maybe empath is simply one of the first of the neo-aetherians to come out of the (deep, dark, cold) closet.

If so, he has some good points to make. We now think space can be ripped apart and put back together with formerly contiguous parts displaced from each other (according to Brian Greene); it seems to be packed with energy (vacuum energy) til it's coming out of its pores (dark energy); it apparently can be dragged by the Earth (frame dragging, recently confirmed); and so on.

In short, empty space is a lot more like aether than we thought fairly recently.
posted by jamjam at 2:54 PM on May 19, 2011

jamjam, no, it's not. Frame dragging is a consequence of GR, which is about as anti-aether as you can get. The point of the aether is to set up a "stationary" frame of reference in the cosmos which light propagates relative to - something NOT affected by the matter around it. The Michelson-Morley experiment kills that dead, and relativity is the theory that explains why we don't need that frame. Though modern theories make the vacuum much more interesting what with the dark energy, quantum foam, and such, it's still relativistically invariant, and so not consistent with an aether interpretation.
posted by physicsmatt at 7:27 AM on May 20, 2011

Maybe empath is simply one of the first of the neo-aetherians to come out of the (deep, dark, cold) closet.

Nope. Accidental double negative.
posted by empath at 7:37 AM on May 20, 2011

It is being replicated in vacuum and in air, thousands of times a day, across the globe. Michelson interferometers are a workaday part of precision measurement, and if the aether (US: ether) had any effect, industrial records would show such.
posted by IAmBroom at 11:59 PM on May 23, 2011