Here's another possibility:

http://www.astronomy.com/~/link.aspx?_id=cfe3e160-af13-448d-96d4-c65aeacb1cb4&utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+astronomy%2ForOJ+%28Astronomy.com+News+-+Presented+by+Astronomy+Magazine%29

Aren't both theories simply "explaining" one asymmetry in terms of another, equally inexplicable asymmetry?
Either way, the inbuilt asymmetry "just is".

Unexplained, I think, rather than inexplicable. If the statements in the Astronomy article are correct, there is a further fundamental interaction in addition to the four we know about; and knowing that there is something to discover, is a first step towards discovering it.

Evolving wrote:Unexplained, I think, rather than inexplicable.

Inexpicable on the basis of one big bang.

If the statements in the Astronomy article are correct, there is a further fundamental interaction in addition to the four we know about; and knowing that there is something to discover, is a first step towards discovering it.

That is precisely what I was referring to. It only moves the explanation onto other inexplicable asymmetries.
There is a better model, IMO, in which asymmetries in laws are the result of gravity effects in a muiltiverse:
http://www.rationalskepticism.org/physics/loop-quantum-gravity-t9397-100.html#p1211883
et seq.

Which leaves us with the need to account for the pear-shaped nuclei.

But there may be a perfectly banal explanation for them.

Evolving wrote:Which leaves us with the need to account for the pear-shaped nuclei.

...

No. I'm not saying they're wrong, just that it isn't an explanation of the lack of anti-matter, without reference to a more fundamental cause. In other words, their explanation needs explaining, even if it's correct.

Just for my own edification, am I right in thinking that if we see matter and not anti-matter in the observable universe due to annihilation then it logically stands that before these annihilation events occurred there was an unequal amount of matter and anti-matter as both are annihilated equally.

That is precisely the issue. At any rate in that region of the universe that has in the meantime become the observable universe.

Evolving wrote:That is precisely the issue. At any rate in that region of the universe that has in the meantime become the observable universe.

Can we say for sure that matter/antimatter annihilation events are always equal? Is there the possibility for one or the other to remain?

What happens when a particle of matter collides with its anti-particle is that they combine to form a particle whose quantum numbers are the addition of the respective quantum numbers of the original particle and anti-particle.

By the definition of an anti-particle, that addition has to give zero for all quantum numbers, and a particle whose quantum numbers are all zero is a massless force carrier - usually a photon.

So there is always something left, but it can't be a particle of matter or anti-matter.

Legal disclaimer: Unless, of course, the standard model is wrong!

mattthomas wrote:

Evolving wrote:That is precisely the issue. At any rate in that region of the universe that has in the meantime become the observable universe.

Can we say for sure that matter/antimatter annihilation events are always equal? Is there the possibility for one or the other to remain?

That's what we are studying right now. We've gotten as far as trapping anti-hydrogen nuclei indefinitely. Next step is to see how it annihilates.

Actually I should add that electrons and positrons, and neutrinos and anti-neutrinos, as well as the photons etc, can also be produced when baryons encounter their antiparticles at high energies, but the sum of their quantum numbers is still zero, so there is still just as much matter as anti-matter, just like before the collision - just less of both.

Again for my own edification, if the result of a matter/antimatter collision is a Gamma ray and this exists essentially as photons, when a photon is absorbed by an atom, can this energy transform in any way?

Not sure what you mean by "transform", Matt.

if an atom or a molecule absorbs a photon, it enters into an excited state, and will usually fall back into a more relaxed state very shortly afterwards, emitting one or more different photons, each with a characteristic wavelength (thus helping us to detect what element this was, if we happen to be watching).

I'm not even sure, I'm trying to recall something I read once upon a time that was probably pseudo-scientific ballsnot

I'm just trying to throw up the remote possibility that the net result of an annihilation event could be matter... (shrugs)

Evolving wrote:What happens when a particle of matter collides with its anti-particle is that they combine to form a particle whose quantum numbers are the addition of the respective quantum numbers of the original particle and anti-particle.

By the definition of an anti-particle, that addition has to give zero for all quantum numbers, and a particle whose quantum numbers are all zero is a massless force carrier - usually a photon.

So there is always something left, but it can't be a particle of matter or anti-matter.

Legal disclaimer: Unless, of course, the standard model is wrong!

Photons are their own anti-particle, like any chargeless boson.
The standard model might well not be wrong, but also not the whole truth.

Evolving wrote:Not sure what you mean by "transform", Matt.

if an atom or a molecule absorbs a photon, it enters into an excited state, and will usually fall back into a more relaxed state very shortly afterwards, emitting one or more different photons, each with a characteristic wavelength (thus helping us to detect what element this was, if we happen to be watching).

It also gets a momentum "kick", because a photon has momentum as well as energy:
http://en.wikipedia.org/wiki/Photon#Physical_properties
Momentum, P=h/wavelength, or energy/c

... Actually, as a result of the conservation of momentum as well as energy, annihilation results in two photons, not one:
http://en.wikipedia.org/wiki/Annihilation

Here is a Nature article on the same subject. Doesn't say anything about a new fundamental interaction!

Evolving wrote:Here is a Nature article on the same subject. Doesn't say anything about a new fundamental interaction!

The article is for subscribers to the OU only. I cannot see it.