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Speed of Light Inconstant?

Posted by michael on from the still-can-count-on-death-and-taxes dept.

DHR writes "Australian scientists have discovered that light isn't quite as fast as it used to be." We've done previous stories on these findings. Those of you with subscriptions to Nature can read the actual paper, the rest of us will just have to suffer.

5 of 496 comments (clear)

  1. Re:Australian scientists by prismatic · · Score: 2, Informative

    Honestly, its sentences like this where it really matters if you use "there" vs "their."

    I honestly thought, the first few times I read it, that it was referring to somebody's mate, like girlfriend or wife, as opposed to "hey there, mate, that's not a light ... now that's a light."

    --
    Brian Voils
    "A university is what a college becomes when the faculty loses interest in students."
  2. I actually read the paper... by Peter+T+Ermit · · Score: 5, Informative
    ... and it adds absolutely nothing to the argument over whether there are time-changing constants.

    As other people have pointed out, the fine-structure-constant-is-changing work came out a year ago. The fine structure constant is a function of the speed of light, c, and the charge of the electron, e.

    This particular article argues that e can't change much over time without causing inconsistencies, so they conclude that c must have been changing. No new data, no new support for the constant-is-changing theory. (And the original study was pretty damn flawed. This paper isn't bad.)

  3. Re:An old poke at physicists. by Bingo+Foo · · Score: 2, Informative
    prime number = natural number that have exactly
    two divisors : 1 and itself.

    1 only has one divisor = 1

    But you didn't say "exactly two unique divisors," so:

    • Is 1 divisible by 1? Yes.
    • Is 1 divisble by itself? Yes.
    • Is 1 divisible by any other natural number? No.
    Therefore, 1 is prime.
    --
    taken! (by Davidleeroth) Thanks Bingo Foo!
  4. Re:questions by Peter+T+Ermit · · Score: 3, Informative
    You shouldn't take popular press versions of science papers literally; often the reporter has no more understanding of physics than you do. That being said...

    The discovery means faster-than-light travel, which is prohibited by the law of relativity, may one day be possible.
    I think this is an error on the reporter's part. I don't see how this is at all related to the paper, unless the reporter thinks: "Speed of light changing therefore Einstein was wrong... Einstein was wrong, therefore we can travel faster than light."

    If the speed of light was close to infinity, immediately after the Big Bang,
    Again, a problem with the reporter here. "Close to infinity" means nothing. What this probably means is that the further back you travel in time, the bigger the speed of light was, and as you approach the Big Bang, the speed of light goes off to infinity. A physicist would say that the speed of light diverges, rather than saying it gets close to infinity.

    The photons [...] interact with the electrons in the gas clouds, charged particles that orbit the nuclei of the metal atoms. This leaves a fingerprint on the light as it arrives on Earth, called the fine structure constant, Murphy explains.
    This is actually close to correct, though it's misleading. The fine structure constant equals 2(pi)e^2/hc (if I recall correctly) where e is the charge of the electron, h is the Planck constant, and c is the speed of light. The value of that constant is related to the electromagnetic force, which, in turn, affects the spacing of the lines in an element's spectrum. Conversely, by looking at the spacing of the lines in elements' spectra, you can figure out the fine structure constant.

  5. One and Primes by chrislike · · Score: 2, Informative

    This is from the top of my head, and as such, may have some errors, especially dates.

    Now that that disclaimer is done with ... there are more reasons to think of One as prime that there are to not, and the primary reason to think of it as a non-prime, non-composite integer is one more of practical value than mathematical correctness.

    You see, the Fundamental Theorem of Algebra says, briefly, that every number can be reduced to a unique, finite, multiplicative set of prime numbers.

    Now, if one were prime, we would run into the terrible, horrible problem of this being false. And all mathematics would slowly fall with it. Because if one were prime, one would be equal to:
    1 x 1
    1 x 1 x 1
    1 x 1 x 1 x 1 ...
    et all.

    However, before the 1800's or so, one was in fact considered to be a prime number -- as math was not then a practical discipline. At all. And it was considered prime because, from a theoretical standpoint, it is, as it only has the factors of itself and one. Nowhere did it then say that those must be unique factors.

    anyway, just thought I'd shed some light, given the posts on top of posts that are a bit off on what it is to be prime.