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Science

Why Is Gravity the Weakest Force? 207

StartsWithABang writes: If you calculate the forces between two fundamental particles separated by subatomic distances, you find that the strong, electromagnetic or weak nuclear force could all be the strongest, dependent on the particulars of your setup. But throw gravity in there, and it turns out to be weaker by some 40 orders of magnitude. This discrepancy, that gravity is such an oddball, is known as the hierarchy problem, and is by many measures the greatest unsolved problem in theoretical physics. Yet the new, upgraded run of the LHC has the potential to uncover any one of four possible solutions, some of which we have hints for already.
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Why Is Gravity the Weakest Force?

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  • Hype (Score:4, Interesting)

    by Anonymous Coward on Saturday December 12, 2015 @01:27AM (#51103977)

    Theoretical particle physicist here. These claims are hype. Pure wishful speculation to entice funding agencies via the general public. They should be ashamed of themselves. Best to ignore them. Cui Bono.

    • Re:Hype (Score:5, Interesting)

      by Beck_Neard ( 3612467 ) on Saturday December 12, 2015 @02:11AM (#51104051)

      To be fair to them, it's a very tough time for fundamental physics right now. Progress is insanely expensive, funding is all but non-existent, it's hard to find talented scientists who actually want to study it, and the general public just isn't interested anymore.

      • Im sure the govt has many secrets and break thrus that they are keeping secret.

        Imagine if it was easy to create a worm hole to cut a planet in half, ISIS would dare do that and we dont need some wacko muslim doing that.

        And yes there is a secret shadow govt, and secret highly advanced break away civilization with tech decades beyond mainstream, that probably has deep space convoys and ships and far off bases etc.

      • Re:Hype (Score:5, Interesting)

        by greenfruitsalad ( 2008354 ) on Saturday December 12, 2015 @06:10AM (#51104411)

        i disagree with the part about talented scientists. there are plenty of theoretical scientists in physics but nothing for them to do (funding problem). the brightest 0.1% get a job in their field, 1% stay at their university for life, the rest sell used cars or teach high school physics.

        i know a guy how knows a guy... who worked at LHC and i heard about how the jobs dried up during the hiatus. theoretical physics is not a field i'd study if i wanted a safe career.

        • by mikael ( 484 )

          From the jobs adverts I have seen, anyone with a 2:1, a PhD from a red brick university in Physics or Mathematics will be headhunted by the financial industry to work in derivatives and trading algorithms.

        • I know a guy who worked at CERN and seriously it's only a place you want to stay if you're a hardcore physicist. These guys do research because they love it, not for fame or big money. How many persons of the general public can name a theoretical physicist next to Stephen Hawking? These guys easily find their way into other areas like Software Development, R&D, All forms of analytics like statistics and machine learning.
          Here are some official stats for the last couple of years (https://www.aip.org/stat
        • I'm sure there are plenty of talented scientists in fundamental physics. But are the MOST talented scientists there? I doubt it. In the 90's and 2000's they were sucked away by Wall Street, Silicon Valley, and various academic research fields (biology, neuroscience, etc.) that offered both more exciting research and more stable careers.

      • Re:Hype (Score:5, Insightful)

        by InterGuru ( 50986 ) <[moc.urugretni] [ta] [dhj]> on Saturday December 12, 2015 @08:09AM (#51104591) Homepage

        I thought the cost of the LHC was insanely expensive, then I realized we spent more to bail out one sleazy bank ( while the banksters still got huge bonuses. )

      • Progress is insanely expensive, funding is all but non-existent, it's hard to find talented scientists who actually want to study it, and the general public just isn't interested anymore.

        I completely disagree, funding still exists although it is being squeezed by governments who want to fund building better widgets rather than understanding the physics which will let you continue to do this 50-100 years in the future. Given the article it is clear that the public are interested in it - so much so that they will listen to someone like 'startswithabang' who, when it comes to particle physics, doesn't really know what he is talking about since the heirarchy, or fine tuning, problem is all abo

      • Has fundamental physics always been synonymous with gigawatts [wikipedia.org] of energy?
      • Re:Hype (Score:4, Interesting)

        by Dcnjoe60 ( 682885 ) on Saturday December 12, 2015 @12:06PM (#51105563)

        To be fair to them, it's a very tough time for fundamental physics right now. Progress is insanely expensive, funding is all but non-existent, it's hard to find talented scientists who actually want to study it, and the general public just isn't interested anymore.

        There is a reason for this. There isn't a lot of practical application from theoretical physics, particularly given the high cost. Businesses realize this, which is why they don't invest in such research and it is left up to the government. In a time of anti-government spending, no ROI equates to no funding.

        As for the general public not being interested, there is, in the USA, anyway, a strong correlation between the decline of the middle class and funding of science. Why? The rich don't need it and the poor are too busy trying to figure out how to get their own basic needs met. In addition, tax revenues, which fund such endeavors come from a strong economy. Economists will tell you that the economy is driven by the middle class. A strong middle class equates to a strong economy and vice-versa.

        So, in short, yes, the public doesn't care about any of this, because the public is interested in either accumulating more wealth or meeting basic needs. Doing something for the common good has gone the way of the middle class.

      • by khallow ( 566160 )

        To be fair to them, it's a very tough time for fundamental physics right now. Progress is insanely expensive, funding is all but non-existent, it's hard to find talented scientists who actually want to study it, and the general public just isn't interested anymore.

        It's worth noting here that there is an overproduction of PhDs in all areas of theoretical physics (and not by a little bit either, I'd estimate at least a factor of two myself, due to the number of people who publish a few times and then drop off the radar), vast sums are being thrown at fundamental physics, and the general public is as interested as they get for something they'll never understand.

        • by mikael ( 484 )

          It's cheaper to employ PhD students and postdocs than it is to employ full-time staff as lecturers, professors and readers.

        • There's an overproduction of PhDs in all areas of science. I have a PhD myself. There's nothing special about physics in that regard. Yet, on average, PhD unemployment is around 4% or so (and most of that is, I would guess, voluntary unemployment e.g. burnout). So that's really no excuse.

          • by khallow ( 566160 )

            Yet, on average, PhD unemployment is around 4% or so (and most of that is, I would guess, voluntary unemployment e.g. burnout). So that's really no excuse.

            I'm pointing out that while it may be hard to find talented scientists, it's a problem that is solved to the point that they are being overproduced by a lot.

    • by Z00L00K ( 682162 )

      Another question is rather - is gravity a true force or a side-effect of the bending of spacetime?

      Some people have tried to find the so called gravitons. However that may lead to the result that gravitation has a minimum quanta - and wouldn't that result in other problems?

      • I think it's interesting how documentaries always take time to explain how time and space are inextricably connected and then go on to explain one or the other independently. It's common to speak of gravity as if it's a force but you never hear ( in the documentaries ) anyone say graviton.

      • One of the more interesting speculative ideas that real physicists take seriously is that gravity as a force is a side effect of entropy.

        Imagine a spherical screen with radius R surrounding a physical system of mass M. According to the holographic principle, all the physics that takes place within the screen can be described by bits of information that can be thought to be located on the screen. If each bit occupies an area Abit, a total of N = 4ÏR2/Abit bits is available to describe the system surrou

    • It's also dubious as to whether or not there's a problem to be solved. The strength of gravity is what it is. Perhaps the real question is why electrons are so light.

  • I'll tell you why (Score:4, Insightful)

    by fnj ( 64210 ) on Saturday December 12, 2015 @01:32AM (#51103981)

    Because. That's all. There doesn't have to be a reason. The mystery is the puzzlement.

    • You might as well ask "why is the weak nuclear force weaker than the strong nuclear force?"

      And did Forbes open itself up to bloggers recently? These used to be on medium.com.

      • You might as well ask "why is the weak nuclear force weaker than the strong nuclear force?"

        And people do, extensively. Physics is the quest to explain as much as possible of the universe from as few assumptions as possible. Then if you have a few assumptions that explain a lot, you can predict outcomes of experiments/observations and see what happens. History suggests that this works rather well. James Clerk Maxwell found that you could explain electricity and magnetism as one thing instead of two and out of that came radio and electronics.

    • Re: (Score:2, Insightful)

      by Carewolf ( 581105 )

      Because. That's all. There doesn't have to be a reason. The mystery is the puzzlement.

      You could say that about all physics. Physics is all about finding out WHY what we observe is what it is, if you just accept it "because", then there would be no physics.

      • by Aighearach ( 97333 ) on Saturday December 12, 2015 @05:46AM (#51104357) Homepage

        Physics can only predict the future, it can't tell you why anything happens. Only what happens, and when.

    • by KGIII ( 973947 ) <uninvolved@outlook.com> on Saturday December 12, 2015 @06:27AM (#51104423) Journal

      We didn't get our Friday SJW thread. I'm kind of disappointed.

      So, with that in mind, it's because gravity is the female variant of force. Obviously, this makes it weaker. Even the most retarded of forces, magnetic force, is stronger than gravity and it's a mentally retarded male force. The feminists have taken over academia and called it the weak nuclear force to imply that it, a male force, was weaker than the strong independent female force of gravity! Well, the yolk's on them because we now the truth.

      I, for one, am glad of this publicity! I hope more people see this and realize the harm that has come to science in the name of social justice and political correctness.

      • We didn't get our Friday SJW thread. I'm kind of disappointed.

        Lol, I noticed that too...maybe it was some sort of SJW holiday or something.

    • But throw gravity in there, and it turns out to be weaker by some 40 orders of magnitude.

      Elbow room [youtube.com] ?

      Because we are presently living in a wind-up Universe and its mainspring consists of two fundamental forces that are 10^40 apart. As evidenced by the receding galaxies, we still getting all wound up.

      At the end of this cycle the mainspring will snap around and in the next cycle gravity will trump the electromagnetic force by 10^40 to form a battery operated Universe. The charge light will come on and increase of potential (not spatial expansion) will take place.

      The whole thing is the result of

    • Once we know the reason, we can start setting into place the science to change that reason, controlling gravity. Thats why the why is important.

    • Some force has to be the weakest. And perhaps there's some other force 40 orders of magnitude smaller yet. maybe there's some inter multiverse quantum repulsion that causes multiverses to diverge. We just don't know about it.

      Likewise it's possible there's some force 40 orders of magnitude stronger than the strongest forces we know of. perhaps quarks have sub particles that are held together by this but it's so string we've never seen them unbounded.

    • Because. That's all. There doesn't have to be a reason. The mystery is the puzzlement.

      I think there's always a "reason", but the reason doesn't have to have any meaning behind it.

      I drop a ball and it falls to the ground. The reason is gravity (in this case) but there's no meaning involved; that's just how things work or interact.

      To me, meaning implies some sort of value applied or assigned in relation to some context, and it's optional at best when talking about physics or the fundamental laws of space and time.

      Meaning is actually more along the lines of "irrelevant", but people love to fram

  • Sith lord is not behind it !

  • At its current strength. Thank you.
  • It has to be (Score:5, Interesting)

    by Waffle Iron ( 339739 ) on Saturday December 12, 2015 @01:53AM (#51104013)

    Unlike the other three forces, gravity neither cancels out because of negative and positive versions, nor peters out beyond subatomic distances. Its effects are therefore cumulative over huge swaths of the universe.

    If gravity were much stronger, the entire universe would collapse into a singularity, and we wouldn't be here to gaze at our navels about the issue.

    • If we're going to ask "why is it weakest," we ought to also ask, "why does it exist?" Of course down that path lies turtles all the way down.....
      • I got stuck at, "wait, why is this a problem?" There is a huge difference between our values for Planck's Constant and Pi too, why would it be a problem for different things to be at different scales? It doesn't seem to me that they're even puking up a real "why" in the first place.

        And who cares, philosophically, about the proportions of different forces? We don't even know how gravity works, what the mechanism is. Therefore we have no context for presumptions about how strong it should be.

        The details matte

    • by Twinbee ( 767046 )
      If the force of gravity is the inverse square of the distance, what are the 'powers' of the other forces? Cubed, quad power, 10th power?
      • Right - Jeez, give gravity a break. It has to work over the distance of the entire universe and resist the cosmological 'constant' in its field. This isn't just a lazy ex-husband deserving of your criticism.

      • Re:It has to be (Score:5, Interesting)

        by tomxor ( 2379126 ) on Saturday December 12, 2015 @07:20AM (#51104513)

        If the force of gravity is the inverse square of the distance, what are the 'powers' of the other forces? Cubed, quad power, 10th power?

        I always had roughly the same thoughts on this argument, that other fundamental forces don't appear to operate over the distances that gravity does... but it's actually quite logical when you play out the details: The inverse square function of distance is no coincidence, it's comes from the dimensionality of space and an omnidirectional force which is why it applies to other things like electromagnetic waves.

        Other forces are stronger (the strong nuclear force is 10^38 times stronger than gravity at the same distance!) and i think they probably have the same distance function... So why isn't it stronger at large distances? As others have said the main difference between gravity and other forces is it's insatiability, (it's cumulative). When some subatomic particles form an atom, the forces at play are satisfied to some degree and the resulting matter is less reactive (has less attraction to other similar matter); whereas when matter coalesces under the force of gravity, only separation is satisfied, the force is just combines resulting in a denser gravitational force in a region of space.

        Another way to compare is by imagining under what hypothetical scenario another force would act the same way: for instance how could you make a strong nuclear force on a universal scale, you would need a large mass (i.e the size of the earth) of protons or something... and they need to stay in the same place (not fly apart) oh and they need to have not reacted with anything... That scenario would result in a frighteningly large force but it will also never happen because those forces tend to get satisfied on small scales very quickly.

        • by Twinbee ( 767046 )
          Ignoring the cancelling of forces on a micro-local scale, are you saying the power for the strong forces are inverse squared like gravity? If not, what are they?
          • by tomxor ( 2379126 )

            Ignoring the cancelling of forces on a micro-local scale, are you saying the power for the strong forces are inverse squared like gravity? If not, what are they?

            I don't know what kind of distance function the strong force has, my point was more that the cumulative native of gravity is the primary reason why it continues to operates at larger distances.

            I had a look for this anyway and it's a slightly more complicated answer than simply some exponential function: between quarks there seems to be a relationship based force "color force" which means beyond a certain distance the force actually does not diminish at all - however this is only true for a single pair, and

            • by tomxor ( 2379126 )
              Calculating the range of strong force: http://hyperphysics.phy-astr.g... [gsu.edu]
            • AIUI, the strong force, like the electromagnetic force, is caused by the interaction of virtual particles. Virtual particles are particles that come into being randomly but exist a sufficiently short time that we can't detect them. You can reformulate the Heisenberg equation to show that there is a threshold of mass times time that we can't determine any more closely, just like momentum and position. This means that a virtual particle must be in existence for a short enough time that we can't detect a c

        • by suutar ( 1860506 )

          actually, according to this [gsu.edu] the strong/weak forces do not use inverse square, because they're fundamentally different: they're based on particle exchange and the distance at which the particles can get exchanged is related to quantum uncertainty, which drops off a lot faster with distance than just inverse square.

          Electromagnetic is stronger and is also inverse square but it's based on charge differentials, and at macroscopic scales objects tend to be neutral overall which means two planets (for example) hav

        • The inverse square function of distance is no coincidence, it's comes from the dimensionality of space and an omnidirectional force ...

          The PBS series and book, "The_Elegant_Universe" (being just one reference) claims that Gravity should be the strongest force, yet one of the weakest.

          Gravity is also the only force that can transverse different dimensions (sharing it's force), it explains dark matter for me.

      • Re:It has to be (Score:5, Informative)

        by ByteSlicer ( 735276 ) on Saturday December 12, 2015 @09:39AM (#51104819)

        It doesn't really make sense to compare the fundamental forces that way. Only the electromagnetic field and gravity propagate far enough to exhibit an inverse square law. This is simply because the field covers a bigger spherical area at larger distances.

        The strong force stays roughly constant at growing distances. This is because the color field absorbs the energy used to separate the quarks, and interacts with itself via the color force (generating virtual gluons and quarks). When the separation gets too large (i.e. sub atomic distances), the field energy condenses into new quarks close to the original quarks, and the field between the original quarks disappears (almost, but not completely. The leakage makes nucleons stick together).

        The weak force is even harder to describe in this way, since it doesn't really behave like a classical force.

        So how do physicists compare these forces then? Each force is associated with a quantum field, and each field has some probability to interact with some particles. This probability is a constant number called a coupling constant [wikipedia.org], and can be determined by experiment. The fact that C14 has a certain half-life for example is caused by the weak interaction having some probability of turning a neutron in a proton (by changing the flavor of one of its quarks).

        So it's the value of the coupling constants that determines the strength of the force, and on average the many quantum interactions between a field (or the bosons that are its quanta) and other particles (which are also just quanta of a field) manifest as a classical force that exhibits an inverse square law.

        • by Twinbee ( 767046 )

          The strong force stays roughly constant at growing distances.

          You don't mean linear right? So the force is as strong a million miles away as it is just a metre away? If so, that's quite..... odd.

          • Re:It has to be (Score:5, Informative)

            by ByteSlicer ( 735276 ) on Saturday December 12, 2015 @10:26AM (#51105021)

            No, I really meant constant, not linear. It is indeed odd, and known as color confinement [wikipedia.org].
            But this property only exists at very small distances (sub atomic, nucleus scale), because once the field energy becomes too high with bigger distance, the energy is converted to mass, and these new quarks close the distance.
            Outside the nucleus, the color field strength (and thus the strong force) is almost zero, because the colored quarks and gluons in the nucleus have a neutral color charge on average, similar to how positive and negative charges almost completely cancel each other out.

      • Electromagnetism is also inverse square, with a larger constant but with both positive and negative charges.

        The weak force is roughly a negative exponential.

        The strong force is repulsive up to around 0.7E-15, maximally attractive at 0.9E-15, and then decays to 0.

  • Scope and scale are funny things. You can only see so small before it gets REALLY hard to see, even using large chains of tools. Same with really big. Same with really slow or fast. But even from what we can observe - our reality has had a LOT of chances to get the roll of the dice to work out - and we happen to live at one level of scope in this universe that allows intelligent life to hang on, in one spot.

    However the underlying constants unfold though - it doesn't have to be convenient at every level

    • Your comment sounds to me like a really smart mouse crossing the Golden Gate bridge and remarking to a friend, "We sure got lucky all this steel and cables and stuff combined and fell together just exactly right in order to give us a way to get across all that water! Imagine if even one set of cabling fell a few inches over there instead..."

      See, the smart mice know it was all an accident because they've shown they can carefully and deliberately drop logs across a small stream and make a similar structure wi

  • by wylderide ( 933251 ) on Saturday December 12, 2015 @02:00AM (#51104027) Homepage
    We are dragged along by four dimensions as they expand, but we can still move freely in the other three, but not time. Coincidence? Yeah, probably, but maybe not.
  • forbes = ad hell (Score:5, Informative)

    by ljw1004 ( 764174 ) on Saturday December 12, 2015 @02:09AM (#51104045)

    I tried reading that article on my mobile device (doesn't support ad-blocker). Got ten ads. The first was a full-screen block that, after I clicked through, didn't even take me to the article. The other 9 all caused the article to "repaginate" under my fingers when I reached them (or at least, recalculate vertical spacing) and all blocked further text until they'd spent their 1-2 seconds loading.

    What a terrible experience. So sure that I never got to the actual substance of the article before I gave up.

    Oh, also a permanent title bar that takes too much of my small device's limited screen real estate.

    Forbes is a disaster on mobile.

    • Even iOS has ad blockers now. It's very ready to get rid of them.

    • So sure that I never got to the actual substance of the article before I gave up.

      Consider yourself lucky. I didn't even check where links went to, just who posted the story.
      skipped.

    • That is precisely why I upgraded my iPhone 5S to iOS 9, to get an ad blocker (earlier versions of iOS couldn't support them.). It has made sites readable again.

  • ... they are all just plain wrong, and gravity is simply weird?
  • by Feral Nerd ( 3929873 ) on Saturday December 12, 2015 @04:21AM (#51104217)

    Why Is Gravity the Weakest Force?

    Entropy? If there are other universes some of them may have a different set of physical laws due to their big bangs or their aftermath playing out in a subtly different way than in the case of our universe. If some of these other universes have strong gravitational forces they will presumably pass into something resembling the upcoming black hole era of our own universe before developing any intelligent life so let's just be happy our universe has weak gravity.

  • by allo ( 1728082 ) on Saturday December 12, 2015 @05:07AM (#51104303)

    Redirects to forbes.com/welcome, which is an empty page.

    Stop linking sources with crude javascript, please.

  • It is left as an exercise for then reader to make up your own joke about attracting clicks.

    For bonus points, work in a few hipster clichés, all of which are true in the submitter's case.

  • by rocket rancher ( 447670 ) <themovingfinger@gmail.com> on Saturday December 12, 2015 @06:44AM (#51104451)

    if you think about it for a moment in terms of the weak anthropic principle, gravity has to be very weak, because it is cumulative. The Weyl curvature of spacetime, which is the metric tensor that governs the propagation of gravity in free space, acts across the entire Einstein manifold, i.e., everywhere at the same time. If gravity were any stronger, it is pretty unlikely that matter as we understand it would be able to exist long enough to produce objects like humans capable of asking that question.

    With that said, it is not really an important question question on its own, as the over-hyped intro suggests. The important questions pretty much are looking for explanations as to why the universe behaves so differently at different scales and velocities. Important questions in physics and cosmology are more along the lines of "Why are our two most successful theories about the nature of the universe, quantum mechanics and general relativity, incompatible with each other?"

    • Thanks for the lucid posting. I'll qft this..."Why are our two most successful theories about the nature of the universe, quantum mechanics and general relativity, incompatible with each other?"...as an elegant summary. One day we'll perhaps have an elegant summary that reconciles the two theories, after, I imagine, we figure out why we can't detect most of our universe.

  • Because if it wasn't, we wouldn't be here to observe it.
  • Maybe it's because most physicists don't consider gravity a force anymore. It's a warping of space which takes a lot of energy/mass and that's why it's so weak.
  • Whether this is design or natural selection/optimization is immaterial. The question is stupid though.

  • Because it doesn't even lift

  • If you use Planck Units [wikipedia.org] then all your coefficients (G, Ke etc) are set to a value of 1. All fields and forces are now the same. The basic equations governing the behavior of energy and matter do not favor one force over another.

    Matter itself is now the issue. The question changes from "Why is Gravity the Weakest Force" to "Why is matter so fluffy?" (i.e. why is the the mass of elementary particles that make up matter so small relative to their charge).

  • it won't Awaken until December 18th at a theater near you.

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