Antimatter Conundrum Remains After Precision Test
Why isn’t the universe half ordinary matter and half antimatter? Both should have emerged from a big bang.
Antimatter is the flip side of matter: it’s the same except for charge. For instance, an electron is negative, but a positron is positive. As far as physicists can tell, the two are identical in all other properties. Since both matter and antimatter are equally probable outcomes of the big bang, it would seem the universe should contain an equal mix, but it doesn’t—almost all the matter we can see is regular matter. How did that come about? This has been a problem for cosmologists for decades (4/13/07 #6, 11/01/08). PhysOrg calls it one of thebiggest puzzles in physics:
Understanding the matter-antimatter asymmetry is one of the greatest challenges in physics today. Any detectable difference between matter and antimatter could help solve the mystery and open a window to new physics.
To solve the antimatter conundrum, CERN physicists have been looking for differences in charge density or other properties that might have given a slight edge of one over the other. If regular matter predominated, even slightly, it might have annihilated all the antimatter, leaving our universe with the preponderance of ordinary matter we see today.
In “Antimatter Passes Charge Test,” Nature Research Highlights announced the outcome of the latest high-precision test:
The neutral charge on many atoms and molecules has been measured with extremely high precision. The standard model of physics says that hydrogen’s antimatter counterpart should have an opposite charge and so be neutral to a similar level. Any differences between the two could help to explain why the Universe contains more matter than antimatter.
Joel Fajans at the University of California, Berkeley, and his colleagues used data from previous experiments to analyse the influence of electric fields on antihydrogen atoms released from a magnetic trap. They found that the atom was charge-neutral, with a limit 1 million times lower than the best previous figure.
It’s back to the drawing boards, in other words.
Many features of our universe appear fine tuned for life. It’s good there’s not a lot of antimatter around, or the universe would be unstable, subject to violent energy outbursts as the two types collide and annihilate each other.
The antimatter problem is but one of many for secular cosmologists. It’s not a conundrum for advocates of creation. We would expect that God, who made a universe to be inhabited, would give it the properties it needs to sustain life.