A magazine news story on the unification of physics usually begins by saying that Einstein’s general theory of relativity and quantum theory are irreconcilable. The one handles the force of gravity, the other takes care of electromagnetic and nuclear forces, but neither covers all, so physicists are left with a big jagged crack running down the middle of their theoretical world. It’s a nice story line, except it’s not true. “Everyone says quantum mechanics and gravity don’t get along—they’re incompatible,” says John F. Donoghue of the University of Massachusetts at Amherst. “And you still hear that, but it’s wrong.”
The famous physicist Richard Feynman came up with a seamless quantum theory of gravity in the 1960s. It looks much like the quantum theories of the other forces. Just as photons convey the force of electromagnetism, particles called gravitons convey the force of gravity. Where the forces differ is that electromagnetism behaves in essentially the same simple way on all scales, varying only in its general strength, whereas gravity becomes increasingly rococo as you zoom into microscopic scales—signaling that the theory eventually gives way to a deeper one such as string theory or loop quantum gravity. But “eventually” is so far off that physicists can usually neglect the rocococity. In the 1990s Donoghue and others began to use Feynman’s theory as a working, or “effective,” theory; though not the final word, it closes up the crack between gravity and the other forces on medium to large scales.
In 2006 Sean P. Robinson and Frank Wilczek of the Massachusetts Institute of Technology applied the effective theory to see whether gravity changes the way forces vary in strength with scale. If gravity doesn't interfere, electromagnetism should become equal in strength to the nuclear forces at one scale and to gravity at a different scale. Robinson and Wilczek conjectured that gravity saps the strength of the other forces and causes them all to match up at the same scale. The idea didn’t pan out but did get people thinking about how the forces mess with one another.
Last November, David J. Toms of Newcastle University in England argued that even if gravity does not bring all the forces into line, it at least qualitatively reconciles electromagnetism with the nuclear forces. Neglecting gravity, electromagnetism intensifies as you go down in size, whereas the nuclear forces weaken. But gravity emasculates electromagnetism, causing it to behave like the nuclear forces on the very smallest scales.
Wilczek calls Toms’s paper “impressive.” Around the same time, however, Donoghue and his graduate students Mohamed M. Anber and Mohamed El-Houssieny cast doubt on the whole approach. Although gravity surely interferes with the other forces in some way or other, they question whether the effect is so straightforward as a tweak to the force strength. The rocococity of gravity should infect the other forces.
One reason physicists can reach such diametrically opposite conclusions is that the calculations are complicated and no one yet knows how to interpret them. “I really wish I had a physical understanding of what is going on, and I don’t,” Toms says. To paraphrase Ernest Rutherford, discoverer of the atomic nucleus, physicists don’t consider they have understood something unless they can explain it in plain language to a bartender. Fortunately for quantum gravity theorists, the bartenders of the world are a patient group.
Already a Digital subscriber? Sign-in Now
If your institution has site license access, enter here.
See what we're tweeting about
16 Comments
Add CommentI'm no physicist and can't do the math, but I'm struck by the profound, fundamentally reciprocal relationship between particle state mass and wave state motion.
Reply | Report Abuse | Link to thisPhotons linearly self-propagate in the direction of their original emission as an energy wave, manifesting as a zero rest mass particle only when its momentum is absorbed.
More massive particles may be products of the density of the initial universe: upon their original emission they could neither linearly propagate nor be reabsorbed. In these conditions their kinetic linear propagation energy may have been reconfigured, encompassing the material energy and directed internally.
In this configuration, kinetic energy is expressed as the potential energy of mass. External application of additional kinetic energy may be physically absorbed by the potential energy internally directed mass.
As a function of universe density at the moment of emission, particles of matter may periodically manifest as energy waves, linearly propagating in the direction previously determined by the spin property of their otherwise stationary particle state.
The derivation of particle mass may be a function of the particle state manifestation frequency. Conversely to the zero mass, persistently linear wave state manifestation of photons, particles of mass proportionately more frequently manifest in their particle state. Their low frequency manifestation in their self-propagating wave states should correlate to their shorter range, continuously redirected 'wiggling' motion.
Science postulates that dark matter accounts for a universe that continues to expand at an accelerated rate. However, they don't have much experience with it and none directly. But doesn't it seem to add one logical further possibility? Doesn't it indicate that there may be one, or more, of the same four forces (i.e. gravity, electromagnetism, strong and weak atomic) EXCEPT they are 'ANTI' or "dark forces". If that is the case, an interaction with 'POSI' forces might begin to show why Relativity and Quantum SEEM irreconcilable when actually they aren't. Dark energy must derive from SOMETHING! An interaction might produce the illusion.
Reply | Report Abuse | Link to thisWe see that the mainstream theories do not lead to the origin of the forces, mass, half-integral spin and charges i.e. to the foundation of physics. This suggests that we should change our vision of nature. Within the Everlasting Theory, we can answer all questions associated with the fundamental physical quantities. Mass is the most fundamental physical quantity, next energy and next the half-integral spin of the closed strings the neutrinos and binary systems of neutrinos consist of. The gravitational constant is associated with the internal structure of neutrinos so it is constant for sizes greater than the Planck length. The other forces, i.e. the electromagnetic, weak and strong, are associated with the Einstein spacetime composed of the non-rotating binary systems of neutrinos and with the interactions of these components. The photons are the rotational energies of the binary systems of neutrinos. The carriers of the strong interactions are the binary systems of loops composed of the binary systems of neutrinos (pions) whereas the thickened regions of the Einstein spacetime lead to the weak forces – the binary systems of neutrinos (neutrinos also) exchange the binary systems of the closed strings (i.e. the weak ‘photons’) the neutrinos consist of. The weak ‘photons’ are responsible for the entanglement of photons too. There are two spacetimes! The most fundamental Newtonian spacetime is directly associated with gravity whereas the other forces are associated with the Einstein spacetime. The gravitational gradients are impressed on the Einstein spacetime so the Einstein spacetime is only indirectly associated with gravity. Gravity does not interfere with other forces.
Reply | Report Abuse | Link to thisThe quantum gravity question is hard enough for people to grasp without the explanations themselves delving further into nebulous and obtuse verbiage. Isn't it bad enough that a faction of Fermilab fellows insist on Truth and Beauty quarks instead of Top and Bottom as Glashow, Salam, Weinberg, and god intended. Must we now refer to Planck scale gravitational variability as rocococity? The word itself is a liguistic atrocity! Even when Edward FitzGerald first foisted the foibled phrase, he forwarded a functional formalization. But in this context, one might just as well refer to gravity's degree of being blue, for all the good recoining a word will do. Are we to believe that gravity is being outrageous? The description is not contagious--for a force so constantly constrained. But as with all distasteful behaviors, the Tevatron troupe may treat gravity's grotesqueries the way the standard model always has. Just pretend it isn't there, the same way we do with mid 18th century French artwork, and dark matter when it's had too much to drink.
Reply | Report Abuse | Link to thisFie for FitzGerald's foibled phrase, fiatly foisted for physics forces formalization? Goys gamely groping gravity's grotesque gamelan gave gumption gibbering glamor! Querulous quibbling quarks quickly quintupled quantum questions! Rocococity? no-no-no-no-no-no-no-city!
Reply | Report Abuse | Link to thisScotty's shimmering swollen slang speech sounding sinful sagacity's seamy substructure sanely sank such sins!
Deeply drunk dark dialogs deluge delighted droves daring Daliesque decorated decrees.
Fine physics fizzled forlornly failing forthrightness' frankness.
Reply | Report Abuse | Link to thisSo Scotty simply suggested, saying sooth, signing skillful savvy.
Obliviate obstacles obediently!
Convenience canon? Hurrah!!!
The tensor calculus applied in the General Theory of Relativity leads to theoretical results consistent with experimental data. On the other hand, tensor is the generalization of scalar and vector. It leads to conclusion that there are two spacetimes i.e. the scalar spacetime and vector spacetime. The Everlasting Theory shows that mean spin of the particles the scalar spacetime consists of is in approximation 10^66 times smaller than the Planck constant so practically they are the scalar particles. The components of the scalar spacetime always behave as the classical particles. They are not the renewable particles i.e. they cannot disappear in some place and appear in another, and so on. The renewable particles are the quantum particles and their behaviour leads to wave function. Behaviour of a particle (i.e. classical or quantum) depends on mass density of spacetimes or other fields in which the particle is placed. For example, the closed strings and neutrinos in our Universe behave as the classical particles. The closed strings behave as the quantum particles when mass density of a field is about 10^57 higher than the tensor field in our Universe, the neutrinos need fields which have mass density about 10^10 higher than the tensor field in our Universe. We can see that at beginning nature is classical. All particles consist of the scalar spacetime components and mass of a particle is in proportion to total volume of the scalar particles the particle consists of. Mass is most fundamental physical quantity so the Higgs mechanism is not needed. The gravitational constant is associated with the internal structure of neutrinos. Neutrinos transform the chaotic trajectories of the particles the scalar spacetime consists of into the divergent trajectories. The divergently moving scalar particles produce a gradient in the scalar spacetime – it is the gravitational field. Photons travelling between different gravitational gradients change their energies, not speed. The gravitational gradients are imprint on the vector spacetime responsible for the electromagnetic interactions. It causes that the gravity associated directly with the scalar spacetime and indirectly with the vector spacetime we can unify with the electromagnetism directly associated with the vector spacetime via the Kaluza Klein equations. Why cannot we see that CLASSICAL scalar spacetime lead to the quantum physics? Einstein was right because the General Theory of Relativity leads to both the origin of energy-mass and origin of the quantum physics.
Reply | Report Abuse | Link to thisI hate it when that happens.
Reply | Report Abuse | Link to thisya'll may as well have another drink.
Photons cannot escape a black hole but gravitons can. This seems possible since gravitons are mass less. But if they are mass less then they can travel much, much faster than light.
Reply | Report Abuse | Link to thisIf gravitons have only some mass then they could still escape a black hole. This means that as a black hole becomes more massive it would have less gravity.
We need to measure the speed of gravity to "unify physics" properly. Perhaps, we can measure gravity of black holes as a function of their mass by measuring an orbiting black hole. Or, perhaps, the speed of gravity could be measured by measuring the small deviation in an actual orbit, as a function of radius, from an ideal orbit.
Shock waves travel faster than sound. Similarly, gravitons may travel faster than the speed of light because they are "shock" particles.
Reply | Report Abuse | Link to thisBut gravitons may not really be massless. They must follow a different relation between speed, mass and energy; they require a different Planck's constant.
Perhaps, gravitons have negative mass. Instead of "radiation pressure" they have "radiation attraction".
Please also see the theory of Eric Verlinde from the University of Amsterdam, he is making an analogy between thermodynamics and gravity, the effects attributed to gravity can thus be described as results from forces that are on the edge of our universe. In fact to me it is clear that thermodynamics and our perceptible world have the same "laws" because on our scale the unicverse is constituded of billion^billion of particles forming a continuum, this continuum has different "laws" as the quantum scale that constitutes it. Verlinde describes our our universe as an hologram at the border of the fronteer quantum/continuuum.
Reply | Report Abuse | Link to thisI'm laughing so hard that I may have to report you for abuse. Thanks.
Reply | Report Abuse | Link to thisYou arn't related to Spiro Agnew are you? Love it! Wes
Reply | Report Abuse | Link to thisIs Einsteins interpretation that gravity from a body will gradually fade away if that object is removed true...
Reply | Report Abuse | Link to thisOr does it carry on at full strength until the gravity wave has finished.
Or does it disappear immediately.
A test to resolve this once and for all might be useful, unless its been done and im not aware of it.
Anyways Gravitons have no place in reality. Its like saying everything needs a creator...simple minds create simple things.
The key in fundamentally unifying gravity and electromagnetism is to balance attraction and repulsion in keeping with half strength, balanced, and equivalent gravity AND inertia.
Reply | Report Abuse | Link to thisGravity is key to distance in/of space. There is no getting around this central fact. All that one has to do is to stand upright and look directly downward at the ground and feet to notice this most significant (and inescapable) conclusion.
Any complete understanding of gravity will have to address this.
Basically, gravity attaches space; and inertia detaches space. How is space semi-detached from touch then?
The baby grows at the center of the body. This is half gravity, and the semi-immobility therein constitutes half inertia. Full gravity is natural and full motion/mobility.
We are talking of low energy origins of life and experience, are we not?
I would necessarly add that the proportionate reduction of both thought and feeling in/as dream experience involves a center of body experience in keeping with middle gravity and half inertia (half immobility).
Reply | Report Abuse | Link to this(Inertia is resistance to acceleration.)
Note that space is semi-detached from touch in dreams. Touch and gravity may or may not be experienced therein; and, if they are, they are both felt with the equivalent force/feeling of the gravitational mid-range of feeling.
All coincidences (in this post and my prior post)? Not hardly.
Here is the outline of the unified understanding of physics.