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Math Space

Physicists Nail Down the 'Magic Number' That Shapes the Universe (quantamagazine.org) 177

Posted by BeauHD from the precise-measurements dept.
Natalie Wolchover writes via Quanta Magazine: As fundamental constants go, the speed of light, c, enjoys all the fame, yet c's numerical value says nothing about nature; it differs depending on whether it's measured in meters per second or miles per hour. The fine-structure constant, by contrast, has no dimensions or units. It's a pure number that shapes the universe to an astonishing degree -- "a magic number that comes to us with no understanding," as Richard Feynman described it. Paul Dirac considered the origin of the number "the most fundamental unsolved problem of physics."

Numerically, the fine-structure constant, denoted by the Greek letter a (alpha), comes very close to the ratio 1/137. It commonly appears in formulas governing light and matter. [...] The constant is everywhere because it characterizes the strength of the electromagnetic force affecting charged particles such as electrons and protons. Because 1/137 is small, electromagnetism is weak; as a consequence, charged particles form airy atoms whose electrons orbit at a distance and easily hop away, enabling chemical bonds. On the other hand, the constant is also just big enough: Physicists have argued that if it were something like 1/138, stars would not be able to create carbon, and life as we know it wouldn't exist.

Today, in a new paper in the journal Nature, a team of four physicists led by Saida Guellati-Khelifa at the Kastler Brossel Laboratory in Paris reported the most precise measurement yet of the fine-structure constant. The team measured the constant's value to the 11th decimal place, reporting that a = 1/137.03599920611. (The last two digits are uncertain.) With a margin of error of just 81 parts per trillion, the new measurement is nearly three times more precise than the previous best measurement in 2018 by Muller's group at Berkeley, the main competition. (Guellati-Khelifa made the most precise measurement before Muller's in 2011.) Muller said of his rival's new measurement of alpha, "A factor of three is a big deal. Let's not be shy about calling this a big accomplishment."
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Physicists Nail Down the 'Magic Number' That Shapes the Universe More

Physicists Nail Down the 'Magic Number' That Shapes the Universe

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  • Constants (Score:3)

    by backslashdot ( 95548 ) on Thursday December 03, 2020 @05:05AM (#60788966)

    Who sets these things, and how is it maintained across the universe from one place to the next.

    • Re: (Score:3, Funny)

      by AndyKron ( 937105 )
      God does, of course. He is everything and nothing at once.

    • Re:Constants (Score:5, Interesting)

      by Escogido ( 884359 ) on Thursday December 03, 2020 @05:47AM (#60789032)

      So perhaps you could flip this question and ask "why a stable (in our admittedly limited understanding of the term) universe can only exist given these particular values". Maybe the answer is, Darwin style, because other universes exist but for such tiny fractions of time that we are incapable of perceiving them as existing. Maybe the answer is, what is a "tiny fraction of time" to us for them is the whole period of time between their hypothetical Big Bang and their hypothetical heat death (or whatever flavor of the ultimate favor of the universe one is a fan of), and they do exist, just, again, we cannot perceive them as existing.

      FWIW, laws of physics are basically laws of mathematics with really big numbers, and so in this regard pi is more fundamental than c. it is not entirely un-possible to imagine a universe with a different value for C/d (having to do with curvature) - just maybe we aren't capable of interacting with anything there, and as such it remains entirely in the realm of thought experiment - logically consistent but purely hypothetical, making one question whether the word "exist" even applies here. https://www.youtube.com/watch?... [youtube.com]

      • Re:Constants (Score:5, Interesting)

        by The Evil Atheist ( 2484676 ) on Thursday December 03, 2020 @06:51AM (#60789166)

        So perhaps you could flip this question and ask "why a stable (in our admittedly limited understanding of the term) universe can only exist given these particular values".

        Not yet, because there could be other combinations of values that form their own web of stability. Yes, if you change any single constant, this universe can't exist, but there's no saying what other constants could take on other values to accommodate the effect of each other to remain stable.

        • I don't know if anyone has made the connection but here:
          https://people.wou.edu/~shawd/... [wou.edu].
          "In Extremistan, inequalities are such that one single observation can disproportionately impact the aggregate, or the total."
          If the makeup of the universe is Extremistan then the history is written by tiny details.
          Spontaneously one will interpret this as an anthropic principle: since these tiniest details would not have occurred if you shift parameters/events then somehow there must be something special about the para

      • Re:Constants (Score:5, Informative)

        by Joce640k ( 829181 ) on Thursday December 03, 2020 @07:49AM (#60789290) Homepage

        So perhaps you could flip this question and ask "why a stable (in our admittedly limited understanding of the term) universe can only exist given these particular values". Maybe the answer is, Darwin style, because other universes exist but for such tiny fractions of time that we are incapable of perceiving them as existing. Maybe the answer is, what is a "tiny fraction of time" to us for them is the whole period of time between their hypothetical Big Bang and their hypothetical heat death (or whatever flavor of the ultimate favor of the universe one is a fan of), and they do exist, just, again, we cannot perceive them as existing.

        It's called the "Antropic Principle".

        https://en.wikipedia.org/wiki/... [wikipedia.org]

      • Re: (Score:2)

        by noodler ( 724788 )

        why a stable (in our admittedly limited understanding of the term) universe can only exist given these particular values

        You should remove the word 'only' in your statement. We don't know if this is the only stable configuration.

        Maybe the answer is, what is a "tiny fraction of time" to us for them is the whole period of time between their hypothetical Big Bang and their hypothetical heat death (or whatever flavor of the ultimate favor of the universe one is a fan of), and they do exist, just, again, we cannot perceive them as existing.

        Maybe it is the answer, maybe it is not. But it sure is an arbitrary view of the cosmos. I can fantasize many more 'answers' like this.

        it is not entirely un-possible to imagine a universe with a different value for C/d (having to do with curvature) - just maybe we aren't capable of interacting with anything there,

        Same can be said about parallel cow dung universes where fractals made of spaghetti monsters rule the astral cows.
        It's not entirely un-possible to imagine they're there - just maybe we aren't capable of interacting with anything there...

      • Isn't this basically the anthropic principle? If the constant were different, we wouldn't be here to observe it. We are here, therefore it has this (perhaps unlikely) value in our universe.

      • Re: (Score:2)

        by Bengie ( 1121981 )
        Does "time" really exist if there are no beings to perceive it? If a tree falls in the woods and no one is around, does it make a "sound"? Yes, it makes compression waves, but does it make "sound".
    • Consider the baryogenesis problem. Our universe is dominated by normal matter (as opposed to antimatter) because for some mysterious reason, the big bang produced way more normal particles than anti-particles. By all rights it seems that equal numbers of each should have been produced, but if that was the case they would have annihilated each other and the universe wouldn't exist. Or perhaps, it would have collapsed back into it's original state and gone bang again and again and again until some fluke of

      • Pre-Big Bang, there could have been many Prior Bangs until this one evolved to comparative quiescence.

        Perhaps the first really big bang occurred, if rumors are true, at a Northern Mississippi Target store, where a case of Beanie Babies was opened just before Easter, long, long ago.

    • Technically it is not constant! (Score:5, Interesting)

      by Roger W Moore ( 538166 ) on Thursday December 03, 2020 @09:53AM (#60789712) Journal
      It's not technically a constant though because it changes with energy due to vacuum polarisation. The virtual particle pairs in the vacuum polarize themselves in an electric field and so shield a charge. The higher in energy you get the less vacuum there is, the less shielding and so the stronger the fine structure constant becomes.

      Really it is an input parameter to the Standard Model that determines the basic strength of electromagnetic interactions. Since we have no way to derive it we regard it as fundamental. However, because it and the equivalent "constants" for the other fundamental forces all change with energy and appear to converge many particle physicists think that there is some sort of grand-unified force.

      If true then the fundamental forces of nature we see today are all just separate aspects of it and, if true, then just like we unified electricity and magnetism and then EM and the weak force at some point we will add the strong force and then we will have a "grand unified theory" (GUT) of all forces (except gravity). In this case, the strength of EM interactions will be determined by this GUT-mechanism but the energy at which the "constants" for all the forces converge is 10^16 GeV or 14-orders of magnitude higher than the Large Hadron Collider so it may take a while before we find out.
    • <quote><p>Who sets these things, and how is it maintained across the universe from one place to the next.</p></quote>

      "Who sets" is primate ethnocentrism

    • If it is part of creation, it must be Brahma. He is the Lord of Creation.

      But one could argue this constant is actually adjustable by Gods and so keeping at 137.xxx is the domain of Vishnu, the Lord of Preservation.

      Then to destroy the universe to start the next cycle, Shiva, Lord of Destruction, might change it to the value that will lead to either Big Crunch, or simple thermodynamic death.

  • Not new science, just ever finer science. Some call that tinkering

    • Not new science, just ever finer science. Some call that tinkering

      And the best knowledgeable people say (TFS/TFA) "A factor of three is a big deal. Let's not be shy about calling this a big accomplishment.". You're not one of them.

      • Come on now. I'm a physicist, and alpha is a very interesting bit of physics. It's cool.

        However, having someone with a career dependent on continuing grants in the area of improved alpha measurements call this "a big accomplishment" is the same as your local Ford dealer calling the new Mustang "a big accomplishment."

        Why is this a big accomplishment? Why is it important? The right person to answer those questions is someone who is going to use the results. In this case, probably a cosmologist. If this was

  • yet c's numerical value says nothing about nature; it differs depending on whether it's measured in meters per second or miles per hour.

    Wow! I can't imagine how something could be different like that!

    • I don't think the " c's numerical value says nothing about nature" argument is really relevant. Any number can be expressed in another base, or in another unit. What's important are the links between made between constants (as if we could link c and pi).

      • Re:Really? (Score:4)

        by SirSlud ( 67381 ) on Thursday December 03, 2020 @06:37AM (#60789140) Homepage

        Uh, no. You can't express pi as a number in another unit. It's not a measurement. It's a ratio. And expressing a number in another base doesn't change that number. Pi is only a "different number" to you apparently in a base below 4. It's still pi, a countable ration you represent as 3 rocks + a bit of another rock regardless of base it is expressed in, and it's unitless so there's no unit to change.

        • Uh, that's irrelevant to what the post says which is about a link or function between constants.

        • Re: (Score:2)

          by skids ( 119237 )

          I think the focus on "unitless" here is not very helpful. (You can stretch the definition and define "units" of pi as "meters of circumference"/"meters of radius" and pretend the difference between circumference and radius matters). And you can get another related number (2pi) by picking different parts of the circle when deriving using a circle... we only arrive at pi and consider that particular multiple the most fundamental because across most equations where it is useful, that's the value that require

    • Re:Really? (Score:4)

      by cmseagle ( 1195671 ) on Thursday December 03, 2020 @07:04AM (#60789194)

      I think you're missing the point.

      The author is highlighting exactly what's so interesting about the fine structure constant: you can't just tweak the units and get a different number like you can with the speed of light. If you do your physics with velocity units of furlongs per hour and mass units of ounces, the fine structure constant is still ~1/137.

      • Re: (Score:2)

        by jbengt ( 874751 )

        The author is highlighting exactly what's so interesting about the fine structure constant: you can't just tweak the units and get a different number like you can with the speed of light.

        I maybe disagree.
        Pi is a dimensionless ratio, but if you use inconsistent units for the diameter and circumference, you can just tweak the units and get a different number
        Using imperial units, the constant of gravitational acceleration at the surface of the earth is often found in equations of energy, force, and acceler

        • Re: (Score:2)

          by ceoyoyo ( 59147 )

          It's not a stretch. The "speed of light" is a conversion constant, just like G. It arises because we use inconsistent units to measure energy in different situations, and distances along different axes. Using consistent units, velocity is also dimensionless.

    • Re: (Score:2)

      by dfghjk ( 711126 )

      Yeah, that's shockingly ignorant. The speed of light does NOT change depending on the units of measure, only the value that describes it does.

      This is what passes today, and /. editors (and posters) are too ignorant to even recognize it.

      Yes, it's true that unitless constants don't have this property because, well, you can't change the units. Great stuff.

    • Re: (Score:2)

      by ceoyoyo ( 59147 )

      Much more mind-blowing is the fact that that statement isn't really correct. c isn't the speed of light in a vacuum, it's the conversion constant between the unit we use for distance along the the spatial dimensions and the unit we use for distance along the time dimension.

      We don't measure c in metres per second or miles per hour, we measure space in metres or miles and time in seconds or hours. c is just the proportionality constant that arises because we insist on using different units for the two measure

  • Can't we just reset our numbers so that a=1 and pi=3? I realise it would be a lot of work, but we did it for y2k so its not impossible. Or is this just a case of scientists keeping things hard to protect that sweet big pharma money?

    • Re:Number reset (Score:5, Informative)

      by Vlad_the_Inhaler ( 32958 ) on Thursday December 03, 2020 @06:55AM (#60789174)

      Indiana came close to mandating Pi as 3, back in 1897. Their House approved it unanimously, their Senate may have done so as well except that a mathematician happened to be there and pointed out the insanity of this proposal. The Senate then put off voting on this measure indefinitely.

    • Can't we just reset our numbers so that a=1 and pi=3?

      Not both at the same time, but you could use base alpha or base pi/3 in stead of base 10 to have one of those. Of course, all your other numbers become rather unwieldy.

      Setting c = 1 is easier: just use years and light-years (or seconds and light-seconds) for your units, in fact we do this so often to simplify calculations that we call those "natural units" [wikipedia.org].

    • Re: (Score:2)

      by ceoyoyo ( 59147 )

      Sure. You can make pi anything you like, for example, by choosing the appropriate base. If you want pi to be a whole number, you have to choose a base that's irrational, which is convenient for some things and rather inconvenient for others.

      If you want pi to be a whole number though, why 3? 1 is much nicer.

  • the "fine" number is very close to 137, which is a prime number.
    • It's so interesting that it's caused at least one physicist (or mathematician, I forget which) to get too enamored with the numerology of it.

  • actual magic number: (Score:5, Funny)

    by Gravis Zero ( 934156 ) on Thursday December 03, 2020 @06:38AM (#60789142)

    FYI, 1/137.03599920611 comes out to be 0.00729735256278127818185819108975920244120061397552490234375
    That means the real number (should you be searching for universe files is):
    E6 3F 24 AC 29 D4 E3 7D

    Do note that universe files are stored in Big Endian format.

  • As fundamental constants go, the speed of light, c, enjoys all the fame

    Pi and Tau are very upset about this claim.

    • Sounds like it could be a quote from Hitchhiker's :D

    • e is pretty cool too

    • Pi and Tau are very upset about this claim.

      Erm...

      The speed of light, c, is constant anywhere you go in the universe. The ratio of the diameter of a circle to it's circumference, a.k.a. pi* is not. Pi is only constant in Euclidean geometry, but this universe isn't Euclidean. You will get different values near a black hole.

      [*] This is why the definition of pi is usually a bit more specific, precisely so it is a constant.

  • In the dumpster fire that 2020 has been, it gives me hope to read "Here we use matter-wave interferometry to measure the recoil velocity of a rubidium atom that absorbs a photon..." and "Our result modifies the constraints on possible candidate dark-matter particles proposed to explain the anomalous decays of excited states of 8Be nuclei and paves the way for testing the discrepancy observed in the magnetic moment anomaly of the muon in the electron sector". Sadly, that is all that I can read, so we can j
  • eight.

    We are 138.

    We are 138

    In the eyes of tiger.

  • Dont waste your time. We know the answer. It is 42.

    • Re: (Score:2)

      by PPH ( 736903 )

      We put our best Pentium on the task of calculating the number. Turns out its 41.9997.

  • e * pi * phi (golden ratio) * a * 100 = 1.0 . Not exactly one, but a good obfuscation of such when exact precision is not needed.

  • They also found it was not constant (Score:3)

    by OpinOnion ( 4473025 ) on Thursday December 03, 2020 @10:27AM (#60789858)
    The universe may actually have poles like a planet and the laws of the universal constant may change as you get closer to them. These changes can completely re-define what objects and forces could exist if the fine-structure constant really does change at those locations or others in the universe and maybe explain problems with matter distribution. >The fine structure constant has not changed in time. ... Earlier results have shown that the fine structure is slightly different along a specific axis of the Universe, called a dipole. Now, the latest result is from a single light source along a specific direction, so it's not definitive on its own

  • The guy who came up with the number (Score:5, Interesting)

    by Sique ( 173459 ) on Thursday December 03, 2020 @11:13AM (#60790008) Homepage
    The guy was Arnold Sommerfeld [wikipedia.org]. He was recommended for a Nobel Price 81(!) times and (in most years for both Physics and Chemistry), and is thus the most recommended person in the history of the Nobel Prize. Nonetheless, he never got one.

  • Wow these guys are slow, we have known this since the 70s.

  • One of the questions I’ve asked people when hiring for a mechanical engineering position was “the torque force an engine puts out is measured in foot pounds (in the us) while the definition of work is force over distance, how can force and and work have the same units?”

    The answer is you specify a torque at a distance to get a force but there is no motion to make work from just torque alone. By adding dimensionless rotation, such as by 2 pi a revolution, you can then get force over dista

  • CTL-F 42 (Score:2)

    by mwa ( 26272 )

    Seriously? Nobody yet?

    Am I that old now?

  • Maybe it turns into a rational number when using base e

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