ether in physics...

Discussion in 'Physics' started by scythe, Jun 19, 2009.

  1. scythe

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    I've been reading an old discourse by an electrician at the turn of the 19th century, and he mentions "ether" quite a bit. I've done some reading around and apparently it was believed to be the medium through which electricity and light sent waves out through space. What I'm wondering is if there are any scientists today who believe in something like it, or if the belief really did die out with Einstein's theory of relativity. If the latter case is true, does anyone know of the last prominent scientists that pursued the theory? Just curious.
     
  2. beenthere

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  3. Papabravo

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    I don't think Einstein had a great deal to do with it. It was James Clerk Maxwell who formulated the famous equations which bear his name in the 1870's, a good 30 years before Einstein came into his prime. Although Maxwell believed in the Ether, nothing about those equations requires a medium, empty space is just fine. It is true that special relativity did put the nail in the coffin so to speak.
     
    Last edited: Jun 19, 2009
  4. KL7AJ

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    When you look at modern quantum mechanics....where all of space is infused with an infinite number of particles "as if swimming through a particle soup" as one renowned physicist explains it...it's really hard to distinguish this from the ancient concept of Ether. If it walks like a duck, and quacks like a duck, it's a duck, by any other name. The bottom line is that empty space isn't empty. Call it ether, call it particle soup...the implications are the same.

    eric
     
  5. studiot

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    Whether we consider the Aether to have a quantum minestrone or a classic fluffy candy floss structure the same question arises

    We should be able to detect a difference when something that interacts with the Aether is whirled about a circle. There will be a difference of twice the tangential velocity relative to the Aether when the detector is on one side of the circle going one way compared to when it is on the other side going the other way.

    this was the basis of the Michelson Morely experiment which produced the startling result that there was no detectable difference.

    It is uncertain how much Einstein knew about this result when he was developing relativity.

    It is however cetain that relativity makes some interesting predictions (modifications) to thinking about electromagnetism.

    Consider a line of evenly spaced charges, such as in a neutral wire.
    Let this wire carry current in the x direction.

    Now consider a charge q moving parallel to the wire with near light velocity v.

    There are two observers, on in the S system at rest relative to the wire and one in the S' system moving with the charge q.

    Both observers note the same force between the charge and the wire.

    However they disagree fundamentally about the origin of this force.

    The S observer sees a line of evenly spaced charges moving past as equal to a current and thus sees the resulting magnetic field as the origin of the force on an also moving charge q.

    The S' observer however sees the charge q as at rest and therefore not able to be influenced by a magnetic field.
    However because of the Lorenz-Fitzgerald contraction he does not see the charges in the wire as evenly spaced. thus he sees the wire as charged, not neutral and the force as electrostatic in origin.
     
  6. beenthere

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    With respect, the Aether you speak of is really a fundamentally different animal form the traditional luminiferous ether.

    Before the determination of the speed of light (Michelson & Morley killed two birds at once), light was assumed to have infinite speed. It was known to be a wave phenomenon, as interference effects could be demonstrated.

    However, classical waves can only propagate in a medium. That called for the concept of the lumineferous ether as the medium through which light waves moved. The LM had to be harder than diamond to support the waves, but also imperceptible by ordinary matter, which was absolutely unaffected by this crystalline substance - perhaps we might think dark matter as the modern debatable substance that is similar in nature (imperceptibility).
     
  7. scythe

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    Cool! That was a lot of stuff I didn't know. Thanks for the posts.
     
  8. Ruptor

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    Space is and therefore must have a structure all be it one that we can not comprehend at this time. The way I visualise space is as a sea of neutrinos. They are not charged and impossible for us to detect so are a likely candidate for the fabric of space. The neutrino detection experiments give pointers to the fact that neutrinos are there because the results of the measurements show that a burst of one type of neutrino from the sun ends up as three different types being received. If you consider space as a sea of neutrinos that contains all three types then chucking a burst of one type in to the mixed sea would result in an equal proportion of the other types being received on earth as the initial burst transfers its energy to others through space. But that’s just my thoughts to enable me to visualise how space might exist.
     
  9. studiot

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    Anything we can interact with can be detected by the interaction.

    If we can't interact with it then it may as well not exist.
     
  10. Wendy

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    Which is the current gripe with String Theory. For a theory to have real meat, it must be testable in some way, that is, make predictions that are different from what we would expect to happen.
     
  11. jpanhalt

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    Which is, of course, a key distinction between religion and science.

    Is the ACLU aware of the dangers presented by teaching string theory in our public schools?

    John
     
  12. Wendy

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    Personally I think testability will happen. The instrumentation hasn't caught up yet. We have all these experiments that strongly hint at the multiple universe theory, other dimensions can't be too far away.
     
  13. studiot

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    What about Perelman's proof of the Poincare conjecture?
     
  14. Wendy

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    Care to provide a link to that? I don't have a clue what you're talking about.
     
  15. Mark44

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    Apparently not completely impossible. I recall some experiment being done years ago where they had huge underground reservoirs of some liquid (carbon tetrachloride?). Every once in a while a neutrino would interact with a molecule in the liquid and emit a photon which would be detected by a sensor. It was a while back that I read about that experiment, maybe 30 years ago.

    Here's some trivia with regard to the Michelson-Morley experiment that quantified the speed of light. That experiment (or at least part of it) was carried out in Los Angeles, CA, at the Griffith Park Observatory. Light form a source at the observatory was reflected off a panel on a mountain about 100 miles away, at Idyllwild, CA. That panel was still there when I lived in Idyllwild for about 9 months in 1970-71. It's possible that other sites were involved in the experiment; if so, I don't know of any.
     
  16. studiot

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  17. Wendy

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    Cool. Thanks. I'll have to get back to reading of that, it looks like a large lump to digest all at once. Basically it is related to the hypercube, from the quick glance I gave it.
     
  18. studiot

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    Its about possible shapes for the universe and why objects with three dimensions are special compared to 1, 2, 4, or 5 or more.

    String theory requires lots of dimensions.

    In simple terms a three dimensional universe has only one possible shape (euclidean), whereas there are lots possible if you allow more dimensions.
     
  19. Ruptor

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    I should have used the words "impossible to isolate at this time" since if you read the next line I described the implication of the results of the experiments you have referred to about the detection of neutrinos. The experiments have been on going for many years and all three types of neutrino have been found but as I said only one third of the expected quantity have been detected by each experiment implying that the original burst from the sun of type 1 gets converted to equal numbers of type 2 and type 3.
     
  20. someonesdad

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    The Michelson-Morley experiment is one of the most famous (if not the most famous) "failed" experiments. It was unable to detect what was postulated to exist (the ether). This does not "prove" there is no ether, but it does set an upper bound to its properties should it exist. Many other measurements in the intervening 100+ years have lowered that upper bound.

    Contrary to popular opinion, the Michelson-Morley experiment did not measure the speed of light (though Michelson did quite a bit of work in that area too). It looked for a difference in propagation velocity in different directions using the Michelson interferometer. Most physics students get to play with one in their second or third year -- it's a brilliant technical device with manifold applications. Tidbit: when I was a student taking atomic physics, we used a Fabry-Perot interferometer to look at the sodium doublet. To this day, I remember my shock sitting in a dark lab room looking at the interference pattern and realizing that my eye was able to see the color difference between these two spectral lines, which, if memory serves, are a few tenths of a nm apart in wavelength. Of course, I've long forgotten what the actual experiment was about... :)

    An interesting read is to go back and look at some of Michelson's calculations done on his speed of light experiments. They show a facility with basic arithmetic (via logs) which I'll bet fewer than one in 10,000 scientists or engineers could do today. As I went to college before calculators existed and had to do such calculations as they were done in past centuries, I occasionally do some simple calculations using long arithmetic and logs. I'm humbled by the fact that I've lost what little facility I had in the intervening 37 years or so since hand-held electronic calculators became available.
     
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