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posted by cmn32480 on Wednesday April 15 2015, @01:44PM   Printer-friendly
from the not-your-momma's-chevy-nova dept.

Science Daily has an intriguing article, "Accelerating universe? Not so fast", which notes the discovery that type Ia supernovae, which are used as a 'standard candle' for measuring distances in the universe, actually come in two different subtypes. Though nearly indistinguishable in normal optical frequencies, the differences became apparent when examined in the ultraviolet. The significance is two type IA supernovae having the same luminosity may actually be located at different distances from us. This, in turn, calls into question how fast the universe is expanding.

So, if I measured the brightness of a "100-watt bulb" at 1km, and then measure another "100-watt bulb" and find it to have the same brightness, I would assume that it, too, was 1km away. Apparently some "100-watt bulbs" are dimmer than others — and, according to the inverse square law, would be closer to me than 1 km.

I've been unable to determine how much a difference this would cause in our estimation of the rate of the expansion of the universe. Also, I suspect this might affect our 3-D maps of the universe and what is located where. How will it affect the current thinking about "dark energy"? How much of an impact are we looking at here? What else might be affected?

[Continued after the break]

From the article:

The team, led by UA (University of Arizona) astronomer Peter A. Milne, discovered that type Ia supernovae, which have been considered so uniform that cosmologists have used them as cosmic "beacons" to plumb the depths of the universe, actually fall into different populations. The findings are analogous to sampling a selection of 100-watt light bulbs at the hardware store and discovering that they vary in brightness.

"We found that the differences are not random, but lead to separating Ia supernovae into two groups, where the group that is in the minority near us are in the majority at large distances -- and thus when the universe was younger," said Milne, an associate astronomer with the UA's Department of Astronomy and Steward Observatory. "There are different populations out there, and they have not been recognized. The big assumption has been that as you go from near to far, type Ia supernovae are the same. That doesn't appear to be the case."

The discovery casts new light on the currently accepted view of the universe expanding at a faster and faster rate, pulled apart by a poorly understood force called dark energy.

[...] "The idea behind this reasoning," Milne explained, "is that type Ia supernovae happen to be the same brightness -- they all end up pretty similar when they explode. Once people knew why, they started using them as mileposts for the far side of the universe.

"The faraway supernovae should be like the ones nearby because they look like them, but because they're fainter than expected, it led people to conclude they're farther away than expected, and this in turn has led to the conclusion that the universe is expanding faster than it did in the past."

An abstract is available, article is paywalled.

Because of the slightly different colors for these groups, NUV-red SNe will have their extinction underestimated using common techniques. This, in turn, leads to underestimation of the optical luminosity of the NUV-blue SNe Ia, in particular, for the high-redshift cosmological sample. Not accounting for this effect should thus produce a distance bias that increases with redshift and could significantly bias measurements of cosmological parameters.

 
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  • (Score: 0) by Anonymous Coward on Wednesday April 15 2015, @02:57PM

    by Anonymous Coward on Wednesday April 15 2015, @02:57PM (#170983)

    believers should welcome such attacks as much as us non-believers.

    believers ? we're talking science here, not religion.

  • (Score: 2, Insightful) by Anonymous Coward on Wednesday April 15 2015, @03:09PM

    by Anonymous Coward on Wednesday April 15 2015, @03:09PM (#170991)

    Science is impartial, scientists aren't.

  • (Score: 4, Insightful) by FatPhil on Wednesday April 15 2015, @03:35PM

    by FatPhil (863) <pc-soylentNO@SPAMasdf.fi> on Wednesday April 15 2015, @03:35PM (#171016) Homepage
    Well, Hawking and I believe that, as we progress, science gets less wrong. Which implies that we should be prepared to replace it with a better one when one comes along. We are therefore in a state of uncertainty as to how long it will be before our current theory is replaced.

    For example, did Kepler not, after making his measurements and calculations, believe that planets orbited the sun in ellipses? His belief was based on evidence - his fastideously-obtained measurements, and some solid mathematical theorems - but it's still belief. And he was correct in that belief... until he was wrong. And that's science. Anyone who does science with absolute unshakeable certainty, is not doing science.

    Please learn some metaphysics.
    --
    Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
    • (Score: 2) by Gaaark on Wednesday April 15 2015, @04:52PM

      by Gaaark (41) on Wednesday April 15 2015, @04:52PM (#171061) Journal

      What do you think of the ideas of Julian Barbour, trying to remove time from space in a more Machian way?
      According to an article in
      https://edge.org/conversation/the-end-of-time/ [edge.org],
      'Stephen Hawking "might be quite sympathetic, because he's been basically working along those lines for many years now"'

      I like Barbour's work, because it has an Occam's razor aspect for me: it is more believable for me that 'time' and space are separate and that time is only an aspect of the movement of 'things' through space, than that there are (26?) imaginary dimensions in space and that "we'll find them some day".

      Any thoughts about that? (truly interested in hearing pros and cons).

      --
      --- Please remind me if I haven't been civil to you: I'm channeling MDC. ---Gaaark 2.0 ---
      • (Score: 2) by FatPhil on Wednesday April 15 2015, @09:42PM

        by FatPhil (863) <pc-soylentNO@SPAMasdf.fi> on Wednesday April 15 2015, @09:42PM (#171190) Homepage
        Unfortunately his school is tainted by having one too many loons (the "motion is impossible" ones). He has quite a mathematical approach, and it's not particularly new, it's just like the phase spaces from way back. Minkowski's space-time can easily be viewed that way. I can't understand how he gets what we know about General Relativity to work in his system, but that's because I've not looked into either it or GR deeply enough. However, http://www.gravity-and-light.org/lectures/ is in a browser tab, and I shall at least brush up on that side of things.
        --
        Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
        • (Score: 2) by Gaaark on Thursday April 16 2015, @12:37AM

          by Gaaark (41) on Thursday April 16 2015, @12:37AM (#171259) Journal

          Wow... he lost me in lecture one when he started talking about 'curly O's', and monsters, sub-sets of a set, and etc. (http://www.gravity-and-light.org/lectures/)

          Will stick with it a bit longer, but it may be quite beyond me. :(

          --
          --- Please remind me if I haven't been civil to you: I'm channeling MDC. ---Gaaark 2.0 ---
          • (Score: 2) by FatPhil on Thursday April 16 2015, @07:20AM

            by FatPhil (863) <pc-soylentNO@SPAMasdf.fi> on Thursday April 16 2015, @07:20AM (#171433) Homepage
            I was lucky in that I'd done all of that stuff, even though it was 25 years ago and in a different order and with different connections (I had epsilon-balls and metrics before I had topologies, which made his approach seem at first quirky, but to be honest simpler - as he said, you want the theory based on the fewest assumptions). I'm sure I'll hit the wall before too long, though.
            --
            Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
    • (Score: 2) by c0lo on Wednesday April 15 2015, @10:49PM

      by c0lo (156) Subscriber Badge on Wednesday April 15 2015, @10:49PM (#171224) Journal

      Please learn some metaphysics.

      Epistemology will suffice.

      --
      https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
      • (Score: 2) by FatPhil on Thursday April 16 2015, @07:35AM

        by FatPhil (863) <pc-soylentNO@SPAMasdf.fi> on Thursday April 16 2015, @07:35AM (#171440) Homepage
        Thank you, that's a much better word, more precise. I hovered over the submit button for a while thinking "is that the word I really want" as metaphysics has morphed way too much since its coining. "philosophy of science" was a blander term I thought of but deliberately avoided, as that newly-named field is nothing more than what metaphysics was in the first place, and I object to its unnecessary renaming.
        --
        Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
        • (Score: 2) by c0lo on Thursday April 16 2015, @11:33AM

          by c0lo (156) Subscriber Badge on Thursday April 16 2015, @11:33AM (#171524) Journal

          as that newly-named field is nothing more than what metaphysics was in the first place, and I object to its unnecessary renaming.

          In my understanding, you are wrong:

          1. metaphysics - what are the nature, existence and relations between the two (admits idealism, with the solipsism in extreme)
          2. ontology - what's existence/evolution, what does it mean to be/become.
          3. epistemology - what does it mean to know/believe.

          While the last two branches may be coerced to accept idealist positions (George Berkeley managed to spectacularly rape them). most of their successful applications are nested into the realist philosophical views.

          --
          https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
          • (Score: 2) by FatPhil on Thursday April 16 2015, @12:21PM

            by FatPhil (863) <pc-soylentNO@SPAMasdf.fi> on Thursday April 16 2015, @12:21PM (#171541) Homepage
            In your understanding, the tomes from which I get my histories and definitions of terms are wrong. (Which is mostly some 1000-page dictionary of philosophy.)

            Which, given the wide disparity in philosophical texts, is not a huge surprise - it's a field that thrives off different interpretations of things. (Which is why I don't care to too deeply dable, the history I find more interesting than the philosophising itself.)
            --
            Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
  • (Score: 0) by Anonymous Coward on Wednesday April 15 2015, @05:57PM

    by Anonymous Coward on Wednesday April 15 2015, @05:57PM (#171088)

    All of mathematics, and thus most of science, is built on faith - faith that, because theorems correlate well to reality, that they will always do so. Its easy to test 2+2, and its relatively easy to find out something's area, but its not possible to physically test much of mathematics, so we can only have faith that the correlations will always hold.

    • (Score: 2) by HiThere on Wednesday April 15 2015, @07:37PM

      by HiThere (866) Subscriber Badge on Wednesday April 15 2015, @07:37PM (#171159) Journal

      The problem isn't testing the math, it's finding the areas where it maps onto the universe. You can add 2 marbles + 2 marbles and get four marbles, but if you add 2 clouds and 2 clouds you may get any number between 1 and 4...and that's assuming you didn't need to move them in the process of adding them, but just did a superposition (perhaps by observing at different wavelengths).

      --
      Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.