Antimatter asymmetry: new results bring solution closer Physicists are inching closer to explaining why we – and anything else made of matter – exist, with new results inching closer to an explanation of the universe’s matter-antimatter asymmetry. If matter and antimatter were created in equal quantities in the Big Bang, some kind of asymmetry is needed to explain how enough matter …
Is it possible that all the antimatter is simply on the other side of the universe?
Here is a theory: Imagine the universe being a sphere, with one hemisphere made of matter and the other hemisphere made of antimatter. Now we have equal amounts and there's no odd asymmetry to explain. Our little planet is, of course, in the matter hemisphere... and we can't see the antimatter side because it is too far away over there on the other side.
I assume that cleverer people than me have already thought of all this and come up with some valid reason why it can't be true, can someone please explain it to an amateur like me?
We should be able to se gamma rays from the annihilation in the border between the hemispheres. But we don't see them.
And also you have to find an explanation for this asymmetric distribution.
Those experiments, on the other hand, prove that there's a measurable difference between matter and anti-matter in the sense that the latter decays more easily. And that's the explanation of why just one out 10^9 survived annihilation. (we can use this decay ratio to find out if an alien is made of antimatter before shaking his hand)
Not seeing annihilation radiation simply rules out our living close enough to see it. We don't know what the universe looks like past the edge of the visible universe, no idea how big it really is.
You can't even turn to the 'special place' principle because in a large enough matter/antimatter distributions it could be much more probable we live far from any edge.
Lack of this observation just puts some constraints on how small our chunk of matter is and how it evolved. Working out a mechanism that allowed such large distribution patterns would almost certainly be new physics ;)
Firstly, there is a big bump in the background radiation at 511keV, the electron-positron annihilation energy, it is not "absent", its just not enormous. Secondly there are flavours of theory that posit antimatter being gravitationally "negative" with respect to matter - i.e.they repel each other but attract themselves. This would cause a large scale clumping together and explain the low annihilation rates, to an extent. Think of two feather boas intertwined but not touching, this structure forms naturally from the simulations.
If all this seems a little outlandish, and I would love to put in relevant links but i'm working, consider the scale of the problem, we can account for 4% of the universe's mass, 23% is dark matter, which we know nothing about, and 74% is dark energy, which we really know nothing about...
We don't know if antimatter is gravity repulsive (they are trying to measure this with anti-hidrogen experiments), but again, those experiments on decay ratios are showing that there's a measurable difference between matter and antimatter. The idea is that before the annihilation of the primordial matter and antimatter, around 10^-9 of the total antimatter decayed leaving a surplus of matter.
Of course this is science and this can be all wrong. It would be cooler if antimatter is repulsive because it could be stored more easily and solve lots of transportation problems ...
A sort of left-hemisphere, right-hemisphere universe?
I'm not saying it's impossible (I'm not a scientist anyway) but I think you'd need to invent a new mechanism to explain such a neat and tidy layout. Falling back on 'God did it' wouldn't really cut it.
And where the hemispheres met, you'd get A LOT of matter-antimatter reactions and nobody's seen anything like that.
Or maybe the night sky's going to get VEEEERRRRRRYYYY bright any time now...
"And where the hemispheres met, you'd get A LOT of matter-antimatter reactions and nobody's seen anything like that."
Given that the universe is still expanding, you wouldn't actually get anything meeting at the boudary and reacting, would you?
As I said, I'm only an amateur... an inquiring one.
My concept on the two-sided universe, and I'm no physicist so this is naive, is that there are, well, two sides but the separation is inter-dimensional somehow rather than a 4-space separation like either side of a sphere. There would be a naturally occurring force or condition keeping the two sides separate. It would be easy here to say good and evil, but that would just be silly. Would make a foundation for a really cool science fiction/horror film though, if done well. How would you pass from one side to the other, you ask? Not a mirror, that's been done.
I think this was covered in an old Star Trek episode where you passed through some kind of isolating protective corridor, that good old Mother Nature had set up to prevent mutual annihilation.
I'm sure someone will be able to give a suitable reference for this in a short time.
As a small child, I nearly ran screaming out of the Italian restaurant my family had gone to because I thought that the pasta and anti-pasta would mix in my stomach and explode. I was only 8 at the time, though, and had done way too much ST:TOS, DW and Tomorrow's World than was probably healthy for me.
It just poses another question. Why do these mesons and their anti-particles decay differently?
I would be at all surprised if matter and anti-matter repel each other; something that CERN is looking for a way of testing. Gravity is an effect of matter distorting space. Suppose that anti-matter distorts space differently. And that the nature of the distortion caused by matter affects how anti-mesons decay.
> It just poses another question. Why do these mesons and their anti-particles decay differently?
Ah, you've stumbled upon the truth about science: there is no ultimate answer, it's all about keeping scientists in a job to come up with the next question. Now they will have to find you and silence you.
Its all very well proposing a two sided universe but it raises the same "who did this happen" question as the matter / anti-matter imbalance and as such doesn't really offer an explanation of anything. It is arguably more reasonable (Occam's razor and all that) to speculate that there is some mechanism that produces an imbalance than to speculate there is some mechanism that will neatly separate matter and anti-matter. You should also bear in mind that anti-matter is routinely created (not just in particle accelerators) and certainly doesn't seem inclined separate itself from matter.
When an energetic photon produces a matter-antimatter pair, the residual energy of the photon usually appears as the energy of separation of the newly created particles, which tends to push the matter and antimatter apart. The real question, though, is whether there have been any studies that indicate a preferred direction for the creation of the matter and the anti-matter sides?
Dave
P.S. Mine's the one with the antimatter particles going up (and the beer particles going down, so that they stay in the glass).
The Register 
Biting the hand that feeds IT
Copyright. All rights reserved © 1998–2025
