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Matter/Antimatter from the Vacuum

New work at the University of Michigan, now written up in Physical Review Letters, discusses the possibility of producing matter and antimatter from the vacuum. The idea is that a high-energy electron beam combined with an intense laser pulse can pull matter and antimatter components out of the vacuum, creating a cascade of additional particles and anti-particles. UM Engineering research scientist Igor Sokolov has this to say about the theoretical study:

“We can now calculate how, from a single electron, several hundred particles can be produced. We believe this happens in nature near pulsars and neutron stars…”

That would make the vacuum a lively place indeed, as Sokolov acknowledges:

“It is better to say, following theoretical physicist Paul Dirac, that a vacuum, or nothing, is the combination of matter and antimatter—particles and antiparticles.Their density is tremendous, but we cannot perceive any of them because their observable effects entirely cancel each other out.”

Of course, to produce these hundreds of particles from a single electron, we need not only an ultra-high-intensity laser beam but a two-mile long particle accelerator. But the model is intriguing. We’re deep in the realm of quantum electrodynamics (QED), which describes how electrically charged particles interact by exchanging photons. Richard Feynman called QED ‘the jewel of physics’ because of its predictive capabilities. Feynman’s QED: The Strange Theory of Light and Matter (1986) is based on a lecture series designed for the general public, and without it, those of us who are mathematically challenged wouldn’t have a chance with QED ideas.

Reading the Sokolov paper, I can see that it’s time for me to return to Feynman, or maybe this Wikipedia entry, which calls QED ‘a perturbation theory of the electromagnetic quantum vacuum,’ and goes on to provide a useful backgrounder on the theory’s evolution. But let’s say this: Normally, matter and antimatter destroy each other when they come into contact. The UM team is interested in how this annihilation may be averted under certain conditions. Thus Sokolov colleague John Nees:

“…in a strong electromagnetic field, this annihilation, which is typically a sink mechanism, can be the source of new particles. In the course of the annihilation, gamma photons appear, which can produce additional electrons and positrons.”

One experiment in the 1990s produced effects that the Sokolov paper calls ‘weak and barely observable,’ creating gamma photons and electron/positron pairs, but the new work suggests that ramping up the laser pulse intensity should produce a more definitive result. The UM team’s equations model how a sufficiently strong laser could cause the creation of more particles than were initially injected into the experiment through a particle accelerator. Sokolov again:

“If an electron has a capability to become three particles within a very short time, this means it’s not an electron any longer. The theory of the electron is based on the fact that it will be an electron forever. But in our calculations, each of the charged particles becomes a combination of three particles plus some number of photons.”

The HERCULES laser at the University of Michigan is one way to test this work in a small-scale laboratory setting, but a similar laser would have to be built at a particle accelerator like the SLAC National Accelerator Laboratory at Stanford to work out all its implications, and because no such construction is planned, it may be some time before we can take these ideas forward. The team speculates that their theory may have applications for inertial confinement fusion — I bring this up particularly because of the interest of the Project Icarus team in ICF — but it’s a case of intriguing theory awaiting the experimental infrastructure to test it adequately.

The paper is Sokolov et al., “Pair Creation in QED-Strong Pulsed Laser Fields Interacting with Electron Beams,” Physical Review Letters Vol. 105, 195005 (2010) Abstract/Preprint. The paper is so dense in mathematics that I want to be sure to give you this news release as well.

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Comments on this entry are closed.

  • ProtoAvatar December 10, 2010, 11:13

    If this is validated by experiment, then it is HUGE!
    I can think of at least 3 fundamental laws that will be broken.

  • Greg December 10, 2010, 14:04

    Wouldn’t a plasma wake-field particle accelerator be ideal for something like this?

  • Adam December 10, 2010, 18:48

    Hi Paul
    Amazing result. Makes me wonder just what would be required to pair-produce proton-antiprotons? Seems like a lot of excess leptons would be created, but maybe there’s a way around that.

  • cavan December 11, 2010, 5:46

    The original lectures are available online:
    http://www.vega.org.uk/video/subseries/8

  • Larry December 11, 2010, 7:36

    Are they implying the creation of matter from ’empty’ space, or creating matter from an electron?

  • Gregory Benford December 11, 2010, 14:56

    Paul’s “I bring this up particularly because of the interest of the Project Icarus team in ICF…” reminds me of ICF’s staggering on, despite its track record. I left Livermore in 1971 in part because Teller wanted me to work on the new ICF effort, a bomb simulator tarted around as a fusion energy source. They thought then it might take 5 years. In the 39 years since ICF has burned around 100 BILLION dollars and failed. It will never make electric power and as a rocket fails the elementary geometry test. Yet it’s now invoked for all sorts of uses.
    I particularly deplore the Stewardship program that burns ~$7/year to “verify” by small lab experiments and simulations what actual testing could do for a hundredth of the cost, with real certainty. We certainly know how to blow money, if not actually make experiments work. Place not your faith in ICF.

  • Ron S December 11, 2010, 15:50

    I’m no expert on the details, so hopefully an expert will jump in and correct any errors in what I say here.

    In QED the vacuum is a froth of potential that continuously spits up pair of particle-antiparticle pairs that almost immediately recombine (and therefore don’t effect the macro world). It’s the purported mechanism underlying the Casimir effect(virtual photons) and even Hawking radiation (virtual anything). There is no new physics here. From a quick read of the paper they are concentrating enough energy in one spot that has the (predicted) ability to prevent some virtual electron-positron pairs from recombining, which results in a real electron and a real positron. It isn’t free since the energy injection is enormous. Protons are a much, much tougher problem, both for their 2000x greater mass and need to get virtual quark pairs to cooperate.

  • Greg December 11, 2010, 23:53

    Dr. Benford,
    So you would say that the “fast” ignition method and NIF are dead ends?
    I always though Tokamac in the same way. I’m wondering what a good path would be.

  • Joy December 13, 2010, 17:45

    Greg December 11, 2010 at 23:53
    “So you would say that the “fast” ignition method and NIF are dead ends?
    I always though Tokamac in the same way. I’m wondering what a good path would be.”

    Considering even the heat/pressure containment of a 10 Jupiter mass planet is insufficient to even fuse duterium … Maybe the whole concept of contained microfusion is a pipe dream. Freeman Dyson’s Orion concept of using fission/fusion bombs for propulsion is the only fusion concept I find remotely credible.

  • Natey December 13, 2010, 22:35

    This was what powered the starship in Arthur C. Clarke’s novel, The Songs of Distant Earth! He called it the Quantum Drive.

  • Eniac December 14, 2010, 2:29

    Any photon that has more energy than the lightest particle pair (> 1 MeV, I believe) will happily produce such a pair when in an inhomogeneous electromagnetic field that can provide momentum balance.

    It seems to me that shooting relativistic electrons into a laser beam is the same thing, as from the vantage point of a sufficiently fast electron, the laser photons will seem like gamma quanta of >1MeV, and the electron can provide the momentum balance.

    Of fusion, I think the experiments have shown that it it is possible, both ICF and Tokamak. Fusion has been done, just not all the way to a self-sustaining burn. Due, as far as I can tell, to lots of practical problems, none of which are fundamental, but boy are there many of them. I believe that fusion can be an example where persistence in the face of adversity will eventually pay off.

  • Greg December 14, 2010, 14:35

    Joy December 13, 2010 at 17:45
    Considering even the heat/pressure containment of a 10 Jupiter mass planet is insufficient to even fuse duterium … Maybe the whole concept of contained microfusion is a pipe dream. Freeman Dyson’s Orion concept of using fission/fusion bombs for propulsion is the only fusion concept I find remotely credible.

    I see what your saying, but I’m not sure if the conditions in a “super” Jupiter would be suitable enough to start the fusion reaction. But your right it may all be a pipe dream, if ICF doesn’t pan out, I can’t see how you would remove energy out of a Tokamak to be useful, as most of the work is to keep the energy levels confined in the torus long enough to initiate fusion. So it doesn’t leave us with much to use. The only thing I think of is some form of antimatter catalyzed fusion reaction.

  • torque_xtr December 15, 2010, 5:30

    It seems to me after reading that physics under proposed concept is very similar to that responsible for Hawking radiation, with electric field acting instead of gravitational, and in case of black holes energy is conserved! So very possibly “extracted” energy will be equal to that of absorbed photons, and in actual device energy confersion efficiency would be proportional to cross-sections of processes involved and thus very small…

  • William February 20, 2011, 18:04

    Is this a space drive ?
    -Assuming you can recirculate the electrons- Then you get to use energy only, and throw away something with mass.
    If you can’t keep the electron, is it still an ion drive with improved thrust ?