Do Matter And Antimatter Obey The Same Laws Of Physics?
    By News Staff | June 5th 2011 10:00 AM | 8 comments | Print | E-mail | Track Comments
    The creation, trapping and storage of antihydrogen atoms for up to 1,000 seconds not only represents the longest time period so far that antihydrogen has been captured, but it also brings us closer to answering the question, do matter and antimatter obey the same laws of physics?

    Antimatter particles are routinely produced in particle accelerators as well as in space, but holding onto them, particularly the neutral ones, is difficult because antimatter and matter will annihilate on contact and conventional containers are made of matter.

    The ALPHA collaboration at CERN demonstrated last year that they could instead use a magnetic trap to capture antihydrogen particles, and managed to store them for 172 milliseconds. The team now increase that period by more than 5,000-fold, meaning that the antihydrogen atoms have time to reach their ground state, rather than only existing in the highly excited states created by previous experiments, in which they are quickly annihilated.

    Such long storage times allowed the first measurements of the characteristics of trapped anti-atoms, which provide information about the formation dynamics of antihydrogen atoms and their kinetic energy distribution.  With anti-atom confinement now at 1,000 seconds, an interesting question becomes how long can anti-atoms be trapped?

    Artistic representation of the ALPHA neutral antimatter trap, suggesting the nature of the ALPHA apparatus as a container for antihydrogen.  Credit: Chukman So and copyright © 2011 Wurtele Research Group. All rights reserved.

    Improved traps will potentially provide plenty of interaction time for future experiments to probe the anti-atoms' quantum nature with lasers or microwaves, or to cool them down to study the gravitational effects on antimatter.  
    Although the physical set-ups are different, ALPHA's ability to hold anti-atoms in a magnetic trap for 1,000 seconds, and presumably longer, compares well to the length of time ordinary atoms can be magnetically confined. 

    "A thousand seconds is more than enough time to perform measurements on a confined anti-atom," Prof. Joel Fajans of U.C. Berkeley Lab's Accelerator and Fusion Research Division. "For instance, it's enough time for the anti-atoms to interact with laser beams or microwaves." He jokes that, at CERN, "it's even enough time to go for coffee." 

    The ALPHA Collaboration not only made and stored the long-lived antihydrogen atoms, it was able to measure their energy distribution.  A program of upgrades is being planned that will allow experiments not possible with the current ALPHA apparatus. At present the experimenters don't have laser access to the trap. Lasers are essential for performing spectroscopy and for "cooling" the antihydrogen atoms (reducing their energy and slowing them down) to perform other experiments.

    Fajans says, "We hope to have laser access by 2012. We're clearly ready to move to the next level."

    Citation: The ALPHA Collaboration, 'Confinement of antihydrogen for 1,000 seconds', Nature, June 5, 2011, DOI: 10.1038/NPHYS2025


    Rick Ryals
    To answer the question:  Matter and antimatter *particles do behave the same because they both have positive mass, something that occurs in stark contrast to the naive expectation for the negative energy states.

    For example, why doesn't antimatter fall, up?

    This is a bigger issue than the glossed over reinterpretation that modern quantum theory has adopted to account for the problem, and I have good reason to believe that the bogus interpretation of Dirac's equation is at the root of all of the problems that the cutting edge of theoretical physics is facing now.

    And the solution is much simpler than any of the far-reaching fanatics would ever want to admit.
    Vladimir Kalitvianski
    You are right, of course, and we should not expect a different behavior from antimatter, but who knows for sure, the nature is full of surprises. The only thing that counts is the direct experimental evidences.
    Perhaps mass is not strictly a characteristic property of particles, mediated by the exchange of particles, but an external potential energy field more directly related to kinetic emission/propagation energy.

    In that case, perhaps it was the temporally varying propagation restrictive density of the early universe that produced the varying assignment of mass to differing types of particles, performing the mass assignment function attributed to the imaginary Higgs Field

    Perhaps some conditions in the early universe favored the production of matter rather than antimatter. For example, rotation of the exceedingly dense early universe could have affected the condensation of matter in ways analogous to the rotation of protoplanetary discs preferentially producing complementary rotations of objects and magnetic field alignments.

    Rick Ryals
    Or maybe it's even simpler than that...

    Antimatter particles don't fall up because they would have to have negative mass and pressure in order for this to happen, but what do we know of that has negative pressure?

    If the vacuum structure is ordinary mass energy that is rarefied or "stretched" thin to the point that it has negative pressure, rho<0, then it will exhibit all of the characteristics of a negative mass object and this would account nicely for all of the mysteries that surround the negative energy states, especially when you realize that it would no longer have negative pressure if you condensed enough of this energy down over a finite enough region of space to attain the matter density, rho>0, at which point you have all the makings for an antimatter particle that has positive mass and energy... duh!... and the "duh" is not for you, James.

    If the vacuum structure is the mass energy of a finite vacuum, then particle production drives expansion via the huge hole that gets left in the vacuum when you rip out a huge chunk of it to make a particle pair from condensed vacuum energy... and ya know what?... this would also hold the vacuum stable and flat as the vacuum expands, since the increase in negative pressure that the hole leaves immediately get's counterbalanced by the positive gravitational effect of the newly created particle... speaking of "duh" ways to solve such a long standing mystery without ever having to resort to such extreme unscientific garbage as string theories and multiverses.

    But we're far beyond common sense physics in science now a days, the only hope left for sanity is that the LHC will show them up for the Start Trek sci-fi writers that they really are...
    I'm interested in scientific things but am definately not a scientist. Given that light has both wave and particle types behaviour is there anything we have discovered that would lead us to think about "anti-light"?

    Well, antimatter hasn't got much to do with wave/particle duality: antihydrogen is atoms and in most circumstances atoms are best treated as particles - or rather as a structure of several particles. The wave-type behaviour of electrons is certainly responsible for the "solar system" structure though. And the same structure will emerge in antimatter.  (These are rather outdated pictures but they are good enough for answering your question!)
    As for actual anti-light, no! Antimatter involves changing the charge on a particle, Light is not charged, so there is no anti-matter equivalent.
    However, some clever-Dick is going to point out that some theories predict a whole new set of particles called supersymmetric. So there might be a supersymmetric partner to the photon but I wouldn't hold your breath. It wouldn't be antimatter though.
    Hope that's useful. I'm not an expert but sometimes the blind lead the blind better than a sighted person who runs ahead too fast :)
    Makes sense.... thanks for a quick reply.

    So in theory the sun in an anti-matter solar system would emit light no different than our sun? If the light from our sun and this imaginary anti sun were to meet nothing would happen (unlike if the two suns were to meet).

    Yes. At least that's the conventional view. With a blog asking whether matter and antimatter obey the same laws it would be unwise to be totally dogmatic.
    As a matter of fact, having boldly asserted that they obey the same laws, in some respects they don't! :) The laws of particle physics have a slight twist to them - literally, left is not quite a mirror image of right for the weak force. You can find out about it by googling symmettry. However, this doesn't make any difference to electromagnetism, which *does* seem to be fully symmetrical.
    The possibility that other galaxies are made of antimatter used to be taken seriously but we now know that galaxies collide and although even a galaxy is mostly empty space, so that most stars miss each other, I think there would be some annihilation radiation visible if a matter galaxy collided with an antimatter one. I'm sure someone here can confirm or refute this.