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What would be different if our universe consisted of antimatter?
Hey this has been bugging me since i read a letter in a magazine asking "what would the difference in the universe if anti-matter had prevailed over matter after the big bang"
No i dont pretend to know much about physics let alone matter/anti matter, but i understand that in an anti-matter universe atoms would consist of negativly charged nucleaus with orbiting positive particles.
This could be blindingly obvious but what is positive and negative?? Are the labels interchangable?
Sorry i'm abit confused myself and find it hard to put in into words.
No i dont pretend to know much about physics let alone matter/anti matter, but i understand that in an anti-matter universe atoms would consist of negativly charged nucleaus with orbiting positive particles.
This could be blindingly obvious but what is positive and negative?? Are the labels interchangable?
Sorry i'm abit confused myself and find it hard to put in into words.
Scroll to see replies
So whats the difference between these two electrical charges? What is an electrical charge?
Sorry i dont know much about physics so was just wondering. Why is an electron negative?
Oh also thats what i was thinking about surely if positive and negative are interchangable and opposite then surely an antimatter universe would be no different however in the article i read it did allow for differences but why?
Grrr my head hurts
Sorry i dont know much about physics so was just wondering. Why is an electron negative?
Oh also thats what i was thinking about surely if positive and negative are interchangable and opposite then surely an antimatter universe would be no different however in the article i read it did allow for differences but why?
Grrr my head hurts
uh... good question. Its just a property of matter. Like why do particles have mass?
Nobody really knows for sure, its to do with particle physics and i don't know much about it.
All i do know is that protons etc are made of smaller sub-atomic particles called quarks. Called up and down quarks. Depending on the "Spin" of the quark they have different electrical properties. What is "Spin" i have no idea. I assume they don't actually rotate. But i don't know.
Nobody really knows for sure, its to do with particle physics and i don't know much about it.
All i do know is that protons etc are made of smaller sub-atomic particles called quarks. Called up and down quarks. Depending on the "Spin" of the quark they have different electrical properties. What is "Spin" i have no idea. I assume they don't actually rotate. But i don't know.
~the_one~
"what would the difference in the universe if anti-matter had prevailed over matter after the big bang"
Well, the answer as far as I know (after 2 years of uni physics), is that it would probably be exactly the same. Positive and negative are just names we have given to particles which have charge +e and -e respectively, as a result of the first investigations into electricty.
Anti-matter is exactly the same as matter in every single way, except it has opposite charge. Since we only see interactions between charged particles based on attractions or repulsions, I don't see any reason why the universe would be any different.
Interesting question though.
Worzo
Well, the answer as far as I know (after 2 years of uni physics), is that it would probably be exactly the same. Positive and negative are just names we have given to particles which have charge +e and -e respectively, as a result of the first investigations into electricty.
Anti-matter is exactly the same as matter in every single way, except it has opposite charge. Since we only see interactions between charged particles based on attractions or repulsions, I don't see any reason why the universe would be any different.
Interesting question though.
Anti-matter is exactly the same as matter in every single way, except it has opposite charge. Since we only see interactions between charged particles based on attractions or repulsions, I don't see any reason why the universe would be any different.
Interesting question though.
That would break CPT symmetry.
There exist experiments that can work out matter and anti matter.
Look up CPT symmetry for a full explaination of the differences you might find...
In case you wanted to ask what P (parity) means, a P reversal entails having on of the co ordinates being swapped so its like a mirror image of our universe.
CPT are the three different types of discrete rotations that one can do to the co-ordinate system of the universe.
C reversal is the one you talk about, reversing all the charge, swapping + for - and vice versa.
T reversal is time reversal. This is where all processes proceed backwards.
P is the most difficult to explain...
Thus antimatter is NOT exactly the same as matter just with charge reversed. Else there wouldn't be a matter surplus.
This is one area of active research, why matter dominated and not anti matter.
Mehh
That would break CPT symmetry.
There exist experiments that can work out matter and anti matter.
Look up CPT symmetry for a full explaination of the differences you might find...
In case you wanted to ask what P (parity) means, a P reversal entails having on of the co ordinates being swapped so its like a mirror image of our universe.
CPT are the three different types of discrete rotations that one can do to the co-ordinate system of the universe.
C reversal is the one you talk about, reversing all the charge, swapping + for - and vice versa.
T reversal is time reversal. This is where all processes proceed backwards.
P is the most difficult to explain...
Thus antimatter is NOT exactly the same as matter just with charge reversed. Else there wouldn't be a matter surplus.
This is one area of active research, why matter dominated and not anti matter.
There exist experiments that can work out matter and anti matter.
Look up CPT symmetry for a full explaination of the differences you might find...
In case you wanted to ask what P (parity) means, a P reversal entails having on of the co ordinates being swapped so its like a mirror image of our universe.
CPT are the three different types of discrete rotations that one can do to the co-ordinate system of the universe.
C reversal is the one you talk about, reversing all the charge, swapping + for - and vice versa.
T reversal is time reversal. This is where all processes proceed backwards.
P is the most difficult to explain...
Thus antimatter is NOT exactly the same as matter just with charge reversed. Else there wouldn't be a matter surplus.
This is one area of active research, why matter dominated and not anti matter.
Something I know about!! I went to a Particle Physics day at Imperial, and the lecturer spoke at length about it!Mehh
Thus antimatter is NOT exactly the same as matter just with charge reversed.
I thought that was what it was defined as, e.g. a positron has the same properties as an electron except opposite charge. What's the actual definition?
I did think about the parity reversal thing actually, but couldn't see how it would result in a universe with different physical laws or atomic construction.
The definition is arbitrary. we generally choose matter to be the type of particle dominant in our observable universe. However it does seem that there are experimental differences between matter and antimatter.
Whether they caused the excess of matter in our universe, or that was a freak coincidence is another question.
Whether they caused the excess of matter in our universe, or that was a freak coincidence is another question.
I assume they don't actually rotate.
They do (or at least, they have angular momentum - it's somewhat abstract talking about how a wave has mass etc). There are quantum numbers (don't ask) related to spin and angular momentum.
Worzo
Well, the answer as far as I know (after 2 years of uni physics), is that it would probably be exactly the same. Positive and negative are just names we have given to particles which have charge +e and -e respectively, as a result of the first investigations into electricty.
Anti-matter is exactly the same as matter in every single way, except it has opposite charge. Since we only see interactions between charged particles based on attractions or repulsions, I don't see any reason why the universe would be any different.
Interesting question though.
Anti-matter is exactly the same as matter in every single way, except it has opposite charge. Since we only see interactions between charged particles based on attractions or repulsions, I don't see any reason why the universe would be any different.
Interesting question though.
Hes right, its basicly a mirror image, its all relaitve to itself. We call matter such because that is our reality and so the other possiblity is anti matter, well had the anti matter prevailed we would be sitting her asking the same question, what would happen if anti matter had prevailed, since to us the anti matter would just be matter.
Infact some people will tell you that anti matter moves thorugh time the opposite direction and has not yet exsisted!
How do we know it isnt?
Mehh
Again you just contradicted yourself.
If antimater is like mater going backwards in time then its not like mater with the opposite charge...CPT symmetry.
If antimater is like mater going backwards in time then its not like mater with the opposite charge...CPT symmetry.
would you care to explain what about going backwards in time makes it not just the opposite of matter?
Ahhhh, I think I see now.
Imagine there's magnetic field lines going upwards along the z-axis. If you send in a proton (+C) in the x-y plane, it will follow a clockwise path (+P). This is identical, however, to an antiproton (-C) going backwards in time through the system (-T) and following an anticlockwise path (-P). So in order to recreate our universe from antimatter, we must invert C, P and T?
Mehh or jp...you're the theoretical nuts - I must have gone wrong in that argument somewhere!
Imagine there's magnetic field lines going upwards along the z-axis. If you send in a proton (+C) in the x-y plane, it will follow a clockwise path (+P). This is identical, however, to an antiproton (-C) going backwards in time through the system (-T) and following an anticlockwise path (-P). So in order to recreate our universe from antimatter, we must invert C, P and T?
Mehh or jp...you're the theoretical nuts - I must have gone wrong in that argument somewhere!
Worzo
Ahhhh, I think I see now.
Imagine there's magnetic field lines going upwards along the z-axis. If you send in a proton (+C) in the x-y plane, it will follow a clockwise path (+P). This is identical, however, to an antiproton (-C) going backwards in time through the system (-T) and following an anticlockwise path (-P). So in order to recreate our universe from antimatter, we must invert C, P and T?
Mehh or jp...you're the theoretical nuts - I must have gone wrong in that argument somewhere!
Imagine there's magnetic field lines going upwards along the z-axis. If you send in a proton (+C) in the x-y plane, it will follow a clockwise path (+P). This is identical, however, to an antiproton (-C) going backwards in time through the system (-T) and following an anticlockwise path (-P). So in order to recreate our universe from antimatter, we must invert C, P and T?
Mehh or jp...you're the theoretical nuts - I must have gone wrong in that argument somewhere!
Pretty much. If you think about it, when a matter antimatter pair form they go off in opposite directions. If they meet again, what shape would that form in spacetime? As you said this arguement holds under CPT.
However with the "matter with opposite charge model" this works under the laws of electromagnetism. The transformation of q -> -q produces classically, AND quantum mechanically the same universe.
However there are some, I believe mesons, that under go decay that are STATISTICALLY different from their antiparticle counter part.
For example the meson may have two decay paths. The particle favours one decay path whereas the antiparticle favours the other.
I must however stress that this is about as significant a difference as Newtonian mechanics and Relatvistic Mechanics.
So its not quite that you are not right. But you are right 99.999999999% of the time...Just thought you be interested in that 0.000000001%.
Mehh
I must however stress that this is about as significant a difference as Newtonian mechanics and Relatvistic Mechanics.
Thats not a good example though. To us right now there is almost no diffrenince between the two since the diffrence is so small it can only be calculated mathematicaly.
At high speeds aproaching the speed the light, the diffrence is huge and newtonian mechanics does not work. At the speed of light the reliative speed between two particles moving in opposite directions is in newtonian mechanics twice that of Relatvistic Mechanics since Newton did not know about time dilation and the dilation of space.
Id have thought there must be some demonstrable differences between a particle and its antiparticle other than charge inversion.
Positive and negative charges are just names given arbitrarily to observed states, but I think they'd have to have different properties (other than charge) from each other in order for matter or antimatter to have prevailed at all.
Otherwise, why didn't equal amounts of matter and antimatter be created and annihilate each other instantaneously? (just simple chance maybe? in which case there couldn't have been much in terms of symmetry at the beginning of the universe, and what would have caused these deviations?) I don't really know enough about antiparticles/annihilation and how the universe began to speculate much, heheh.
I dunno, just thrashing around here, ive only got A level physics to go on
Positive and negative charges are just names given arbitrarily to observed states, but I think they'd have to have different properties (other than charge) from each other in order for matter or antimatter to have prevailed at all.
Otherwise, why didn't equal amounts of matter and antimatter be created and annihilate each other instantaneously? (just simple chance maybe? in which case there couldn't have been much in terms of symmetry at the beginning of the universe, and what would have caused these deviations?) I don't really know enough about antiparticles/annihilation and how the universe began to speculate much, heheh.
I dunno, just thrashing around here, ive only got A level physics to go on
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