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In the most stringent test yet of differences between protons and antiprotons, scientists investigated the ratio of electric charge to mass in about 6,500 pairs of these particles over a 35-day period. To keep antimatter and matter from coming into contact, the researchers trapped protons and antiprotons in magnetic fields. Then they measured how these particles moved in a cyclical manner in those fields, a characteristic known as their cyclotron frequency, which is proportional to both the charge-to-mass ratio of those particles and the strength of the magnetic field.
(Technically, the researchers did not use simple protons in the experiments, but negative hydrogen ions, which each consist of a proton surrounded by two electrons. This was done to simplify the experiments — antiprotons and negative hydrogen ions are both negatively charged, and so respond the same way to magnetic fields. The scientists could easily account for the effects these electrons had during the experiments.
The scientists found the charge-to-mass ratio of protons and antiprotons "is identical to within just 69 parts per trillion," Ulmer said in a statement. This measurement is four times better than previous measurements of this ratio.
In addition, the researchers also discovered that the charge-to-mass ratios they measured do not vary by more than 720 parts per trillion per day, as Earth rotates on its axis and travels around the sun. This suggests that protons and antiprotons behave the same way over time as they zip through space at the same velocity, meaning they do not violate what is known as charge-parity-time, or CPT symmetry.
[...]
Using more stable magnetic fields and other approaches, the scientists plan to achieve measurements that are at least 10 times more precise than what they found so far, Ulmer said.
If matter and anti-matter are mirrors of each other, and were created in equal measure by the Big Bang, then where did all the anti-matter go?
See our related story: Time-Symmetric Formulation of Quantum Theory Provides New Understanding of Causality.
(Score: 2) by mhajicek on Friday August 14 2015, @04:51AM
If there were such a boundary there would be either bright walls where matter and anti collide, or dark spans with neither, or both. Unless most of the anti went the other direction in time.
The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek
(Score: 2) by gnuman on Friday August 14 2015, @05:16AM
Antimatter doesn't go in other direction in time. That's kind of easy to show - just look at the experiment. It went forward in time along with the experiment. Same everything, except charge.
So where did all the antimatter go? Best answer is - we don't know!
(Score: 2) by mhajicek on Friday August 14 2015, @05:41AM
How do you know it was going forward? Physics works backwards just the same as forwards.
The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek
(Score: 3, Funny) by tftp on Friday August 14 2015, @06:05AM
How do you know it was going forward? Physics works backwards just the same as forwards.
Perhaps because in this experiment, and in many others, the antiprotons did not appear before they were created. Only thiothimoline does that.
(Score: 0) by Anonymous Coward on Friday August 14 2015, @02:29PM
Ah, but if only thiotimoline does it, then clearly antithiotimoline doesn't do it. So that's clearly an asymmetry between matter and antimatter. Puzzle solved! :-)
(Score: 2) by opinionated_science on Friday August 14 2015, @11:26AM
that's where entropy comes in....
(Score: 0) by Anonymous Coward on Friday August 14 2015, @05:24AM
But we can only see as far as light will allow us in the expanding universe. There could be a dark boundary between the universes that's so far away we will never see it. Not a satisfying answer but possible and could explain the mystery.
(Score: 2, Interesting) by Anonymous Coward on Friday August 14 2015, @08:51AM
If the antimatter is behind the cosmic horizon, we can't see it. We just assume that the complete universe is the same as the visible universe, we can't prove it. But I don't see a fundamental reason why it could not have inhomogeneities on length scales much larger than the visible universe. Such inhomogeneities would not even necessarily mean that the universe is inhomogeneous at the largest possible scales; it could be that they are still local compared to the actual size of the universe. There could be other parts of the universe, unobservable to us, dominated by antimatter (with antihumans wondering where all the matter has gone — well, they'd call our antimatter "matter" and our matter "antimatter" and wonder where the antimatter went, just as we do), and yet other parts where there's no matter or antimatter (and clearly no intelligent life, for lack of matter to make it of).
(Score: 3, Interesting) by tibman on Friday August 14 2015, @02:45PM
Other large structures seem to produce two jets of radiation/matter around a central spinning axis (black hole, quasar, pulsar, and all large quantities of mass). I don't see why the big bang couldn't be similar. Except matter in one direction and anti-matter in the other. Where the clouds of hydrogen and anti-hydrogen meet they annihilate and form a pseudo-boundary wall that is denser when closer to the big bang origin.
That would end up with your theory where there are two "universes" of mostly similar matter types. They share a boundary but by the time enough fusion happens to support complex life we'd be so far away that we couldn't see it. Just like how we currently have no idea which direction is the center of the universe (as in the origin, i get the whole "space is expanding and the center is where you are" thing).
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(Score: 0) by Anonymous Coward on Friday August 14 2015, @07:24PM
You can picture them standing there in their lab coats, stroking their goatees and wondering aloud whether they're the only intelligent life in the universe, and if maybe there's evil copies of themselves, without goatees, out there somewhere.