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Space Science

Can We Test the Speed of Light Using 'Lensing' from Supernovae? (arxiv.org) 112

Long-time Slashdot reader RockDoctor writes: One of the key assumptions of Relativity — both Special and General — is that the speed of light is a constant in all non-accelerating reference frames. As a key assumption, it is also one of the things that gets the kooks, wingnuts and fanatics all riled up, because they have proven that it's wrong, though those pesky scientists refuse to listen to their spittle-flecked presentations.

Back in the real world, real scientists also wonder if the assumption is justified, then try to work out how to test it. One idea for performing this test has just been published — that of using the gravitational lensing of distant supernovae to try to interrogate the speed of light in the distant past.

When a (relatively) nearby galaxy lenses a (relatively) distant galaxy, it is common for multiple images to be formed. If a supernova occurs in the distant galaxy, then supernova images will be seen in the different images, but typically at different times (on Earth) because the light paths from different images are of different lengths, and were of different lengths in the past.

The Chinese-Polish team of authors have studied the possibilities of making such observations and suggest that the LSST (Large Synoptic Survey Telescope, "a wide-field survey reflecting telescope with an 8.4-meter primary mirror, currently under construction, that will photograph the entire available sky every few nights") should detect several thousand gravitationally-lensed distant quasars, and so yield around 50 gravitationally-lensed distant supernovas per year. This is estimated to "produce robust constraints on the speed of light at the level of delta-c/c;= 0.005" (half a percent) in a decade of operations.

Which will shut the wingnuts, lunatics and kooks up. Not.At.All.

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Can We Test the Speed of Light Using 'Lensing' from Supernovae?

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  • it is also one of the things that gets the kooks, wingnuts and fanatics all riled

    I must be way behind on the kook news; since when was the speed of light in a given medium not constant per observer?

    • Re: (Score:1, Interesting)

      by Anonymous Coward

      Dr. Rupert Sheldrake - delusion and dogma in science: (The science delusion). https://www.youtube.com/watch?v=JKHUaNAxsTg

      Discussing the variance of "Big G" i.e. Gravity as well as the measured variance in the speed of light. Nevermind the data, it's stepping on my dogma.

      • by Anonymous Coward
        The guy who thinks that science is wrong because it can't explain absolutely everything? And quite coincidentally he has a hypothesis of everything of his own? I don't think he really understands what science is about.
        Of course that doesn't mean everything he says must automatically be wrong. So please make precise references that illustrate your point and don't expect others to do that job for you.
        • by Anonymous Coward

          Science is supposed to follow the scientific method. Hypothesis, test, etc. Follow the data. Today, you have scientists acting just as dogmatic as religious cult leaders. So, yes, we have a serious problem. There is data that shows anomalies with "Constants" such as Big G, speed of light... Some people start finding data that does not fit the models and they're burned at the stake for not conforming to the bullshit dogma. Questions are good. Science needs challenges. It's the only way to advance.

          • Re: (Score:2, Insightful)

            by Anonymous Coward
            Science needs evidence. Evidence that can be obtained by repeatable and independent experiments. If you can't provide that, you run into problems in science. Then it's philosophy at best.
        • Re:Since when? (Score:5, Insightful)

          by Crashmarik ( 635988 ) on Saturday October 06, 2018 @02:53PM (#57438690)

          The guy who thinks that science is wrong because it can't explain absolutely everything? And quite coincidentally he has a hypothesis of everything of his own? I don't think he really understands what science is about.
          Of course that doesn't mean everything he says must automatically be wrong. So please make precise references that illustrate your point and don't expect others to do that job for you.

          The problem is having faith in the result before the experiment is done. There's been argument over the years about if physical constants are constant and if physical laws have been consistent over time. Anyone who asserts they are or aren't without experimental data to back up their position is equally bad, and not actually using the scientific method or in any way practicing science.

          • This.

            There's really nothing to get upset about here.

            Scientists are probing the universe at different times in order to determine if the speed of light has changed over the billions of years.

            It's a necessary question that we'd like to answer.

            Sure, there are spectators speculating on the outcome of the game before the fucking anthem has even started, but that's not something that's necessarily batshit crazy.

          • by Gr8Apes ( 679165 )

            The problem is having faith in the result before the experiment is done. There's been argument over the years about if physical constants are constant and if physical laws have been consistent over time. Anyone who asserts they are or aren't without experimental data to back up their position is equally bad, and not actually using the scientific method or in any way practicing science.

            So far as I'm aware, those physical constants have held up to all experimental evidence we have today. So accepting them as constants is reasonable for all other work. Until someone provides repeatable proof that they're not constant, this will not change. Kind of like the expansion of the universe and the fact that space itself is expanding. That one blew a lot of assumptions out of the water. So it's not that science is wrong, it's that people who assume that alternate facts can explain something with no

            • The problem is having faith in the result before the experiment is done. There's been argument over the years about if physical constants are constant and if physical laws have been consistent over time. Anyone who asserts they are or aren't without experimental data to back up their position is equally bad, and not actually using the scientific method or in any way practicing science.

              So far as I'm aware, those physical constants have held up to all experimental evidence we have today. So accepting them as constants is reasonable for all other work. Until someone provides repeatable proof that they're not constant, this will not change. Kind of like the expansion of the universe and the fact that space itself is expanding. That one blew a lot of assumptions out of the water. So it's not that science is wrong, it's that people who assume that alternate facts can explain something with no basis is equally valid to experimentally derived theories that are delusional.

              Tell it to the guy who submitted the article with a rather obvious axe to grind. Personally just on cosmology's version of eschatology, I have seen heat death, big crunch, endless expansion, quantum fluctuation cycle and big rip (steady state was alreadyon the way out when I got interested). I may be leaving something out it's not my field. The one thing they all have in common is how remarkably belligerent their supporters have been.

              • by Gr8Apes ( 679165 )
                My main gripe with your comment was regarding

                Anyone who asserts they are or aren't [constant] without experimental data to back up their position is equally bad

                There is no data to prove a constant, only a preponderance of evidence. However, we have no data disproving the constant, and it only requires 1 repeatable test, so the one saying they aren't constants need to come up with some proof.

                TL;DR the naysayers in this case are the ones that need to step up.

    • Re: (Score:2, Redundant)

      by fermion ( 181285 )
      And the kooks speak.

      Science tells us things that are useful and give us rules that appear to function under the appropriate, if sometime unspecified, assumptions,

      So we know that as long as we don't go too fast, among other things, a constant force will produce a predictable acceleration for a given mass.

      But science is new in the grade scheme of things. Until Michael Servetus in the 16th century, people believed that blood just swished back and forth in the body. Until Joseph Priestly we did not have

      • by Altrag ( 195300 )

        Except Einstein did have evidence. It may not have been 100% conclusive but it's not like he pulled it out of his ass either. There was getting to be an awful lot of data suggesting the prevailing wage theory of light was wrong, and Einstein provided a theory that fit all the particle-based data.

        Oh yeah, and he was wrong too. The whole idea of duality didn't come around for a couple decades after he described the photoelectric effect. And you know what he did? He arbitrarily claimed that God doesn't pl

    • by novakyu ( 636495 )

      When the medium is moving relative to the observer: Fresnel frame dragging [wikipedia.org].

      Or did you mean to sound smarter and more informed than you actually were?

      P.S. This whole article is a bunk. It's a long-standing test of symmetries of nature to test if speed of light is constant (as a function of location in universe, or as a function of time). Sure, there are kooky ways to go about challenging it, but there are legitimate ways to test it that had more sensitivity than these methods. See: Is the fine-structure cons [wikipedia.org]

    • Re:Since when? (Score:5, Insightful)

      by Crashmarik ( 635988 ) on Saturday October 06, 2018 @02:47PM (#57438668)

      I am kind of curious how determining if physical laws are constant over time or variable became the province of "Wingnuts and kooks".

      Sounds like Rock Doctor has issues.

      • by DRJlaw ( 946416 )

        I am kind of curious how determining if physical laws are constant over time or variable became the province of "Wingnuts and kooks".

        The "wingnuts and kooks" were identified as those who claim to "have proven that it's wrong."

        Not those still seeking to determine the answer to the question through a rigorous experimental design and (yet to be collected) results.

        • I am kind of curious how determining if physical laws are constant over time or variable became the province of "Wingnuts and kooks".

          The "wingnuts and kooks" were identified as those who claim to "have proven that it's wrong."

          Not those still seeking to determine the answer to the question through a rigorous experimental design and (yet to be collected) results.

          That's one way to read it. I read it as the author thinks anyone who disagrees or has an opinion on the matter different than his, is one or the other perhaps both. It was hard to get past his fuming especially since there had been experimental evidence that purported to show alpha (fine structure constant) had variance in the past, currently there's results from a team at Los Alamos claiming to show the variance. Others have indirect isotope evidence claiming to constrain it. Personally given the sheer com

  • Why not go find out and then let us know? It's not like you're crowd funding here, just wait until you have news.

    • The point is, someone is proposing a method of using a in-construction tool to test this point, as their "card on the table" in the competition for observing time on the scope when it achieves first light. Or, considering it'll be a zenithal scope, whose viewing schedules are dictated by the rotation of the Earth, they'll be bidding for time to observe (and get spectra of) the supernovae that get caught by the LSST, using other steerable scopes that can accumulate the tens of hours of observation needed to
  • Perhaps YOU can, but I'm too busy.
  • What about accelerating ones? Moving along a circular path at some constant velocity has a constant acceleration towards the center of the circle, for instance... is the speed of light any different? I wouldn't have thought so, but if it's only constant in non-accelerating reference frames, I don't know....
    • by jd ( 1658 ) <imipakNO@SPAMyahoo.com> on Saturday October 06, 2018 @12:32PM (#57438096) Homepage Journal

      The speed of light is a constant, time and space change under the Lorenz contraction in a way that keep light fixed.

      (Technically, light only happens to travel at C in a perfect vacuum. C is not otherwise related to light.)

      • by mark-t ( 151149 )

        Well yeah, that's what I figured... so what's this about so-called non-accelerating reference frames then?

        Why bother saying that if it isn't equally true for any reference frame, whether it is accelerating or not?

        • by jd ( 1658 )

          Typical science writer error.

        • Presumably they're referring to the postulates of special relativity but instead of saying 'inertial' they've said 'non-accelerating'.
          • by mark-t ( 151149 )
            My point is that it was my understanding that the speed of light is constant, period. and bringing up any notions of frames of reference is superfluous at best, outright misleading at worst, because it suggests that two different frames of reference could measure two different speeds for light, which isn't true.
            • We assume as little as possible to deduce as much as possible. This is the general principle we follow. In special relativity, Einstein started by assuming the velocity of light, and the laws of physics generally, are the same in all inertial reference frames. At this point, he is not trying to produce an exhaustive list of when it is OK to say the speed of light is the constant 'c'. He wants to make the absolute minimum of assumptions to make his conclusions.

              So can we say the speed of light is absolu

  • Insults (Score:5, Insightful)

    by Anonymous Coward on Saturday October 06, 2018 @11:55AM (#57437924)

    I guess insults are part of science now? Or is this just someone with an expensive speech comm degree writing about science who has been radicalized to hate anyone who disagrees with current theory. As another poster suggested go test the hypothesis and let us know without resorting to insults. If you can manage that.

    • Re: Insults (Score:5, Insightful)

      by jd ( 1658 ) <imipakNO@SPAMyahoo.com> on Saturday October 06, 2018 @12:34PM (#57438102) Homepage Journal

      When insults are the only things listened to, expect to listen only to insults.

      Sorry, you can't blame science writers for copying a broader trend. Blame the trend, or better still fix it.

    • I'm not a science writer. I'm an industrial geologist. And I call idiots,"idiots" when I see them.
    • When idiots revel in ignorance, what is left?

      It is increasingly common to hear people spouting nonsensical pseudo science, or phrases such as "I'm entitled to my opinion" that flys in the face of well proven science, Flat Earth, water powered cars, creationism and such nonsense is common place.

      When somebody will not listen to reason arguments, actual facts, resort to abuse, murder and even terrorism. They are kooks, idiots and morons. If that accurate description offends then change, learn the scientific

      • There is no objective truth, only the powerful trying to dominate us with their version of events. Go read Foucault.
  • It would be possible to calculate the reflected/refracted high energy pulse trajectories and when each known space body's signature would make it to earth. Given sensitive enough equipment, we could use the energy spectrum distribution to figure out what elements are in each one. As a side experiment we would just note how far off from the calculated time and duration the signals arrive... (this reminds me of a similar thing with Mercury, but on a much larger scale).
  • Uh, what? Whick kooks have "proven" that it's false? And why is anyone paying any attention to them, even to debunk it? There's something very big missing from TFS (and the TFA, which I uncharacteristically read).

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