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New, Higher Measurement of Universe's Expansion May Lead To a 'New Physics' (space.com) 139

doug141 writes: Astronomers have measured the universe's current expansion rate (a value known as the Hubble constant) at about 44.7 miles (71.9 kilometers) per second per megaparsec (3.26 million light-years). This is consistent with a calculation that was announced last year by a research team, but it's considerably higher than the rate that was estimated by the European Space Agency's Planck satellite mission in 2015 -- about 41.6 miles (66.9 km) per second per megaparsec. The cause of this discrepancy is unclear. "The expansion rate of the universe is now starting to be measured in different ways with such high precision that actual discrepancies may possibly point towards new physics beyond our current knowledge of the universe," a researcher said. Mike Wall writes via Space.com: "The differences in the Hubble constant estimates may reflect something that astronomers don't understand about the early universe, or something that has changed since that long-ago epoch, scientists have said. For example, it's possible that dark energy -- the mysterious force that's thought to be driving the universe's accelerating expansion -- has grown in strength over the eons, members of Riess' team said last year. The discrepancy could also indicate that dark matter -- the strange, invisible stuff that astronomers think vastly outweighs 'normal' matter throughout the universe -- has as-yet-unappreciated characteristics, or that Einstein's theory of gravity has some holes, they added."
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New, Higher Measurement of Universe's Expansion May Lead To a 'New Physics'

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  • by pahles ( 701275 ) on Friday January 27, 2017 @03:06AM (#53747035)
    What, they were standing on a skyscraper when they measured it?
  • by locater16 ( 2326718 ) on Friday January 27, 2017 @03:09AM (#53747037)
    In other news "new independent measure of hubble constant shows possible difference from previous measurement. Many more measurements and peer review and theory to follow slowly. But this won't give clicks and excitement so we'll exaggerate things as much as possible please click please click please click please..."
    • I don't mind, I'm a glutton for big science news. Beat heck out of People magazine.

    • by Baloroth ( 2370816 ) on Friday January 27, 2017 @10:11AM (#53747981)

      This is one of the "many more measurements". Basically, there are two traditionally two ways to measure the Hubble constant: from supernovae, and from the CMB. Recently (i.e. the past few years) these two sets of measurements have disagreed about the value, with the CMB measurement shooting lower, and supernovae shooting higher, and both sides of the debate having good reasons to doubt the other. This looks to be a method independent of both of the others, which is a really good thing. Not that the linked article explains this, or gives a link to the damned paper which would probably explain this itself.

      • This is one of the "many more measurements". Basically, there are two traditionally two ways to measure the Hubble constant: from supernovae, and from the CMB. Recently (i.e. the past few years) these two sets of measurements have disagreed about the value, with the CMB measurement shooting lower, and supernovae shooting higher, and both sides of the debate having good reasons to doubt the other. This looks to be a method independent of both of the others, which is a really good thing. Not that the linked article explains this, or gives a link to the damned paper which would probably explain this itself.

        44 Miles / second / megaparsec isn't a number that I at all have the slightest frame of reference for in relation to the size and vastness of the units we're talking here and I kind of doubt I'm the only one that doesn't even know where to begin getting a more firm grasp on this topic. Since I'm not at all well versed in this topic and wouldn't know if I looked up faulty estimates, could you enlighten me to the best of your understanding as to how large the discrepancy between the two measurements of the D

        • by nasch ( 598556 )

          I couldn't tell you what the ramifications are but the higher measurement is about 3.5% higher than the lower one. So not something that clearly indicates some kind of massive error like one group was measuring the wrong universe or something, but sounds pretty significant.

        • by Baloroth ( 2370816 ) on Friday January 27, 2017 @06:52PM (#53751901)

          I don't know all the ramifications (as I don't work in either CMB or distance measurement astrophysics), but the difference is pretty small (the Planck measurement was ~67 1/(km*Mpc), compared to this which was 72 1/(km*Mpc)). This measurement, now I look at the actual numbers, is actually closer to the measurement most of the CMB experiments have gotten (Planck got lower than most, albeit with smaller error bars). FWIW, the measurements are all a few standard deviations away from each other (as a rule you need more than 5 standard deviation for results to really be considered in disagreement), so really it's not a major discrepancy.

          If the CMB measurement turns out to be wrong, it *could* indicate some interesting new physics (modified gravity, some new species of dark matter, dark energy doesn't behave quite like we think it does, that kind of thing) which would be very interesting indeed. But, we're still a ways away from being able to say that with any certainty.

          • Damned slashdot with no edit button. That should say "within a few standard deviations of each other". Also, the numbers should read as "67 km per second per megaparsec" and "72 km per second per megaparsec" (I dropped the seconds, and you should ignore the 1's).

      • by Anonymous Coward

        IANAS, but if I had to place my bet it would be on the supernova method being off due to imperfections in our cosmic distance ladder [wikipedia.org]. The ESA's GAIA mission [esa.int] should help refine that the shortest rung of that distance ladder:

        Gaia is an ambitious mission to chart a three-dimensional map of our Galaxy, the Milky Way, in the process revealing the composition, formation and evolution of the Galaxy. Gaia will provide unprecedented positional and radial velocity measurements with the accuracies needed to produce a stereoscopic and kinematic census of about one billion stars in our Galaxy and throughout the Local Group. This amounts to about 1 per cent of the Galactic stellar population.

        More: [esa.int]

        By combining Gaia data with information from these less precise catalogues, it was possible to start disentangling the effects of ‘parallax’ and ‘proper motion’ even from the first year of observations only. Parallax is a small motion in the apparent position of a star caused by Earth’s yearly revolution around the Sun and depends on a star’s distance from us, while proper motion is due to the physical movement of stars through the Galaxy.

        In this way, the scientists were able to estimate distances and motions for the two million stars spread across the sky in the combined Tycho–Gaia Astrometric Solution, or TGAS.

  • There's always a chance that both answers are correct, even though they are different. Depending where you look (and how far back in time), the physical laws of the universe *might* be a little different.

    Einstein said it : "Then again, E=mc^2 may only be a local phenomenon."
    • I've heard similar predictions associated with M-theory. If the separation between our brane and neighboring branes is not uniform, it's possible that the scalar "constants" (e.g., the relationship between mass and gravity) could prove to not be constant.

      Put another way: if there is a place in our universe where the neighboring branes are closer than they are here, an Earth-sized planet might well exert more than 1g of force on objects around it. Conversely, a greater separation between branes might resu

      • I thought it had already been measured and shown to be pretty much flat?
        • Not saying the Universe could be curved . . . saying constants such as magnetism and gravity may not be constant. Like Earth's curvature, this may not be apparent to local examination.
        • Flat in spatial dimensions, yes. That doesn't necessarily mean it's flat in higher dimensions, though. Also doesn't mean there are or are not higher dimensions.

      • The Earth certainly looks flat from my back yard (and even more so from a back yard in Kansas),

        Many people in Kansas know that the earth is flat.

  • by Anonymous Coward

    Those are the craziest units I've seen yet for measuring a frequency.

    • It's for those that can't understand the metric system.

    • It could be worst. What about furlong per fortnight per feet ?!?
    • If you'd prefer, we can use SI, in which case the value would be (approximately) 0.000000000000000001445 per second
    • Those are the craziest units I've seen yet for measuring a frequency.

      The expansion is measured by velocity x distance not velocity/distance. The farther two points are, the faster the outward velocity is along that same line, not near infinite when close and near zero when far apart. So there is no cancelation of terms - it is not a frequency or 1/t.

      • The rate of change in the expansion over a distance is measured as a (change in) velocity / distance. i.e. relative to the observer, a distant point is (due to the expansion of the universe) receding at x miles/sec for every y megaparsecs distance from the observer. This does result in having the units of a frequency (1/time).
  • by Anonymous Coward

    Perhaps this is telling us that Hubble's constant is not a constant.

    • Re: (Score:3, Informative)

      by Anonymous Coward

      The Hubble parameter hasn't been considered constant for a very, very long time. It would only be constant in a deSitter space - where the only energy density is the cosmological constant. The value of the Hubble is determined by Friedmann's equation in terms of the (evolving) energy densities associated with matter, radiation, dark energy, dark matter etc.

      H= 8\pi/3 (rho)

      where rho is the energy density - this changes as the universe expands as the energy densities of matter components change under expansion

      • Re: (Score:2, Informative)

        by Anonymous Coward

        Many apologies, that should be H^2 = 8\pi \rho/3...

  • Why are the SI units relegated to the brackets? We're nerds, we can handle it.
    • Perhaps, more importantly, it's (distance/second)distance. Why not just put the unit in s^-01, or would the electrical engineers in the room mistake it for a frequency?

  • by necro81 ( 917438 ) on Friday January 27, 2017 @09:44AM (#53747875) Journal
    The thing that blows my mind is not that one measurement is higher and another lower, it's just how closely they agree: to less than 10%. This despite the fact that they were arrived at from different instruments and lines of inquiry. The earlier measurement from Planck satellite measurements is derived from measurements of cosmic background radiation. The newer measurement comes from images of gravitational lensing of distant quasars, from the Hubble and Spitzer telescopes. For such a tricky measurements, and such an abstruse topic, I wouldn't have been surprised if they differed by an order of magnitude.* And yet, the agree pretty closely.

    Science is really freaking awesome. Sure, assuming that the expansion is universal and constant (i.e., there is only one value for the Hubble Constant, which is hardly a sure thing), you ought to be able to measure the same answer by any experiment designed to measure it, within the experimental error. I ought to arrive at the same value for the gravitational constant, too, whether I experiment using a precision pendulum, or dropping a cannonball from the tower of Pisa (accounting for air friction, of course), or analyze the tides, or by successfully putting a man on the Moon. It doesn't matter who I am, or where I live, or under which government, or what language(s) I speak - it all still works.

    * Hubble's own initial estimate was about 10x the current values. For those that are interested, here's a graph of the value of H0 [harvard.edu], with error bars, through history. [source [harvard.edu]]
    • The thing that blows my mind is not that one measurement is higher and another lower, it's just how closely they agree: to less than 10%. This despite the fact that they were arrived at from different instruments and lines of inquiry.

      Exactly. Which is why this is clickbait stuff. People who hate science can get excited because they are hoping it proves their world outlook, people who don't hold any particular cosmological ideas, but demand absolute stasis will get uncomfortable.

      Meanwhile scientists and cosmologists are thinking "hmmm, why this little bit of difference, and how might we fine tune it"? Good times.

  • by Anonymous Coward on Friday January 27, 2017 @10:50AM (#53748179)

    There once was a stargazer named Hubble,
    Who said, "We expand like a bubble!"
    But finding the rate,
    Was a source of debate,
    Contention, dissension, and trouble.

  • Oh noes! The "Black Matter Lives" meme is now loose in Slashdot!

    • by Maritz ( 1829006 )
      Black and dark aren't synonyms, and that's why your joke is shite. Sorry. Back to 4chan with you.
  • When you are put into the Vortex you are given just one momentary glimpse of the entire unimaginable infinity of creation, and somewhere in it there's a tiny little speck, a microscopic dot on a microscopic dot, which says, "You are here."
  • by naris ( 830549 ) on Friday January 27, 2017 @01:04PM (#53749029)
    I heard they are black...
  • What about these 2 possibilities:
    1) The rate itself is actually changing.
    2) Measurements are affected by the gravity where measured. i.e. distance to a significant mass.

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