In the Universe’s Decisive Battle, Why Did Matter Prevail Over Antimatter?

By Andrew Moseman | May 21, 2010 11:13 am

TevatronAs opposed to simply energy, the universe is also made of stuff. Not a whole lot of stuff, mind you, at least if you compare the matter we experience to the vast emptiness of space or the preponderance of dark matter. But enough.

The continued prevalence of matter has long been one of my favorite attributes of the universe, given that it allows for the existence of galaxies, and Guinness. However, it’s the source of confusion to physicists. In short, there should have been equal amounts of matter and antimatter present at the creation of the universe, which doesn’t make sense:

If matter and antimatter had come out even in those first moments, they would have instantly destroyed each other, leaving nothing but energy behind [TIME].

But they didn’t; as sure as I’m sitting here, matter won out. And this week, at the Tevatron particle smasher in Illinois, a new clue to the problem has emerged. In a study for Physical Review D, physicist Dmitri Denisov and his colleagues explain that in long-running proton-antiproton collisions (nearly 8 years of them), they saw a slight favoritism toward normal matter in a particular place:

“While colliding protons and antiprotons, which creates neutral B mesons, we would expect that when they decay we will see equal amounts of matter and antimatter,” Denisov says. “For whatever reason, there are more negative muons, which are matter, than positive muons, which are antimatter.” According to DZero member Gustaaf Brooijmans, a physicist at Columbia University, “We observe an asymmetry that is close to 1 percent.” [Scientific American].

The Tevatron team doesn’t know why this asymmetry is there; they just know that it doesn’t make sense based on the current understanding of the universe. And scientists love it when there’s a puzzle to solve. Says team member and particle physicist Stefan Soldner-Rembold:

‘Many of us felt goosebumps when we saw the result,” Soldner-Rembold said. “We knew we were seeing something beyond what we have seen before — and beyond what current theories can explain” [Chicago Sun-Times].

The physics can’t rule out that a new particle would explain this weirdness. And there’s an obvious place to look for it: Europe’s shiny new Large Hadron Collider.

If it turns out that a new particle is in fact responsible for the odd tendency of B mesons to favor matter over antimatter, it might be unmasked in the unprecedented high-energy collisions at the Large Hadron Collider, or LHC. But don’t count out the workhorse stateside, which has a head start of many years—and reams of well-understood data—on its more powerful European counterpart [Scientific American].

Related Content:
DISCOVER: The 11 Great Unanswered Questions of Physics
Cosmic Variance: Matter v. Antimatter 1: The Baryon Asymmetry
80beats: Ghost in the Machine? Physicists May Have Detected a New Particle at Fermilab
80beats: Rumors of the LHC’s Demise Have Been Greatly Exaggerated
80beats: Physicists Shoot Neutrinos Across Japan to an Experiment in an Abandoned Mine

Image: Fermilab

  • RS

    This is proof that we as a species have much to learn about the universe.

  • J Clarkson

    Clearly it is there because “nothing is perfect in the universe” is a fundamental law of nature. If it was perfect, we wouldn’t exist to have this conversation. One of the early conditions of the universe would clearly have to be lopsided here or there to create matters dominance.

  • fb36

    Actually there is a known theory in physics that says anti-particles are particles that move backward in time.
    If it is true then maybe Big Bang really produced matter and anti-matter in equal amounts and later they separated in time w/ one of the twin universes going backwards in time and the other going forward.
    That would also explain the problem of arrow of time.

  • Edward

    I agree with fb36’s reply. Two universes were created by the big bag: matter/positive time and antimatter/negative time.

  • irj

    Statements about the prevalence of matter rather than antimatter in the universe should include the term “as far as we can see”. If we assume that equal quantities of matter and anitmatter were created in the big bang, what we can see now is primarily matter and we see it because of the influence of gravity: galaxies, stars comets etc. If the created anti-matter enjoys anti-gravity then the particles would never form galaxies but would continue to rush away from the big bang and now be out of sight. When will someone measure the gravity force experienced between anti-particles?

  • Trevor

    source on the known theory in physics that says antimatter travels back in time? i am an undergrad student at Colorado College studying particle physics and as far as the physics we know of antimatter isn’t matter going back in time, it’s identical matter of the opposite charge. granted my limited knowledge compared to grad students and actual physicists, i feel like a particle traveling back in time would be a prevalent theory in current physics textbooks and essays

  • Jaleel

    I believe J Clarkson is correct. The imperfection of natural occurrences and nature is considered a fundamental law of this universe and this law may be governed by something called spontaneous symmetry breaking. The initial spontaneous break may have caused a runaway effect so that electrons now dominate. Also, I’m with Trevor, per the standard model of quantum mechanics any subatomic particle could move forward or backward in time and this has nothing to do with whether the object has a positive or negative charge which is basically what we are talking about when we are discussing matter and antimatter particles. If we were in another universe where the atoms are predominately possessed of positrons, electrons would be the basis for antimatter. This has to do with only one of the forces (electromagnetic) and which, so far as we can tell, has nothing to do with gravity. Antimatter doesn’t mean opposite in all ways, in fact it is opposite in just one way, so no anti-gravity (mainly because opposite charges attract and the electromagnetic force is much stronger than gravity) and no backward time travel for antimatter particles as a special case. Now theoretical superluminal particles, that’s a “whole other matter”.


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