Does Antimatter exist in the universe anymore?

[mfb]

@Dryson: That does not make sense at all.

I still don't believe that space is expanding but rather the particles in space are moving through space.

This is not a question of belief. Particles moving through space are incompatible with our observations.

 

[PAllen]

Hannes Alfven in his, now very much dated, 1966 book Worlds-Antiworlds: Antimatter in Cosmology argued that initial annihilation at the boundary would create enough of radiation pressure to push the two kinds of matter apart and subsequently reduce the annihilation rate below detectable levels. I don't remember if he had any calculations there, it's been some years since I've read it. Still, the point can be made that this particular argument can be reasonably circumvented.

There are of course other serious issues with the picture, including the lack of a mechanism to separate matter and antimatter in bulk, but this one is not such a strong one.

Well, that just opens up more questions. Where are those large surfaces without matter (of either kind)? Where are the antihelium nuclei AMS-02 is looking for?

We cannot fully rule out that model, but large amounts of antimatter look very problematic in many aspects.

In early high school (not long after It was published), I was a big 'fan' of Alfven's book. I have a first printing. However, this book was a key part of what led me to pursue study of GR when I read claims it was inconsistent with GR. Indeed, it is fundamentally inconsistent with GR and the book seems blissfully unaware of key mathematical theorems of GR. In particular, this book proposes a cyclic cosmology, but the collapse phase as presented by Alfven would satisfy all conditions of the singularity theorems, so the benign re-expansion powered by boundary layer annihilation is a mathematical absurdity. This book is now only a nice historic curiosity by a very accomplished plasma physicist who seems never to have chosen to put in the effort to learn GR.

 

[UncertaintyAjay]

Do we actually create matter in particle accelerators? I mean , sure we collide particles together but do we actually 'create' matter. If yes, then in what sense?
Also, I'd like to clarify: if all the antimatter was annihilated at the Big Bang, that must mean that there was more matter than antimatter to begin with. Was there? Why?

 

[DennisN]

Do we actually create matter in particle accelerators? I mean , sure we collide particles together but do we actually 'create' matter. If yes, then in what sense?

You could say "produce" or "make" if you like it better :). They don't get created from "nothing". See e.g. http://hyperphysics.phy-astr.gsu.edu/hbase/particles/accel.html and http://www.fnal.gov/pub/science/inquiring/questions/jackie.html.

Also, I'd like to clarify: if all the antimatter was annihilated at the Big Bang, that must mean that there was more matter than antimatter to begin with.

Have a look at http://en.wikipedia.org/wiki/Baryon_asymmetry.

 

[mfb]

Do we actually create matter in particle accelerators? I mean , sure we collide particles together but do we actually 'create' matter. If yes, then in what sense?

The antimatter is not there before, and after the collision we have antimatter (and more matter). I would call that "create".

Also, I'd like to clarify: if all the antimatter was annihilated at the Big Bang, that must mean that there was more matter than antimatter to begin with. Was there? Why?

It does not mean that, see the wikipedia link for details.

 

[UncertaintyAjay]

I was referring to Novas original statement, in which he said that all the antimatter was anhilliated, in which case there must have been more matter than antimatter. The explanations on the Wikipedia page refer to why we do not observe as much antimatter as we do matter . Or how more matter than anti matter could be produced

 

[chkneater]

It goes down to basic relativity... matter and energy cannot either be created or destroyed, only changed from one form to another just like a match going from solid matter to plasma by the addition of heat.

Antimatter, despite the connotation follow the same rules as matter... the big misunderstanding is that antimatter is destructive to matter, and it's not. A molecule of water will interact with its antimatter counterpart it will interact with it as if it were any other molecule. The antimatter particle is a MIRROR image of OUR particles. The charges positions of electrons would be reversed.

The Law of Conservation Mass/Energy states that mass/energy ARE the same thing and cannot be created or destroyed, only transformed from one to the other i.e. My monitor is shooting photons that have mass, it is actually shooting matter at me ONLY because it is plugged into the socket. The electricity TRANSFORMS in mass that I can see.

Antimatter is interesting, takes too much energy to feasibly "convert" mass into anitmatter tho. I'm sure it wil change drastically soon and who knows how they may benefit/hurt us...

 

[chkneater]

My over all point being, yes antimatter CAN be created and converted due to Laws of Relativity and the fact that anitmatter IS mass and reacts like all other mass relatively.

 

[Drakkith]

It goes down to basic relativity... matter and energy cannot either be created or destroyed, only changed from one form to another just like a match going from solid matter to plasma by the addition of heat.

Matter can be created and destroyed, it happens every day at the LHC and other particle colliders.

Antimatter, despite the connotation follow the same rules as matter... the big misunderstanding is that antimatter is destructive to matter, and it's not. A molecule of water will interact with its antimatter counterpart it will interact with it as if it were any other molecule. The antimatter particle is a MIRROR image of OUR particles. The charges positions of electrons would be reversed.

This is incorrect. A molecule of water interacting with its equivalent antimatter molecule WILL result in an annihilation of both molecules. Note that a normal interaction between two water molecules involves a close range repulsion from their respective electrons. Replace one molecule of water with its antimatter equivalent and you no longer have a repulsion between electrons, but a strong attraction between the electrons and the positrons. The end result is annihilation.

The Law of Conservation Mass/Energy states that mass/energy ARE the same thing and cannot be created or destroyed, only transformed from one to the other i.e. My monitor is shooting photons that have mass, it is actually shooting matter at me ONLY because it is plugged into the socket. The electricity TRANSFORMS in mass that I can see.

This is also incorrect. Conservation laws do not state that mass and energy are the same thing and indeed they are not. Einsteins equation e=mc² is commonly claimed to tell us that mass and energy are the same thing, but this is also incorrect. The equation tells us that an amount of energy added or removed from a system results in an amount of mass added or removed to the system, with the amount of mass determined by the equation. Mass and energy are NOT the same thing in physics, though they are related. Also, photons do not have mass even though they have energy.

Antimatter is interesting, takes too much energy to feasibly "convert" mass into anitmatter tho. I'm sure it wil change drastically soon and who knows how they may benefit/hurt us...

Unlikely. Matter/antimatter creation using particle colliders is a very complicated process and it is very unlikely we are going to drastically increase the efficiency in the process anytime soon.

 

[Drakkith]

Unfortunately this thread has generated a lot of pseudoscience and personal theories for responses lately that have had to be deleted. Since the original question has been answered adequately I am going to lock this thread to prevent more troublesome replies.