antimatter worlds

[ritwik]

we know that matter and anti matter particles were created in equal quantities in bigbang. we also know that when they are created they go on on opposite directions.so could there be an antimatter side of universe like matter dominated area.chances of them annihilating each other is meek as they embark opposite ways in a vast universe ...

[Markus Schwarz]

we know that matter and anti matter particles were created in equal quantities in bigbang.

We don't know, but it is the most plausible assumptions. The "matter/anti-matter creation" during the "big bang" is poorly understood, because we don't have a theory that can describe such an early epoch; let alone experimental data. However, the standard model of particle physics has processes that distinguish between matter and anti-matter. The problem is here, that if you calculate how much matter is "left over" from an originally equal matter anti-matter mixture, you get a wrong number. So, how to get the right amount of matter out is an open problem.

so could there be an antimatter side of universe like matter dominated area.chances of them annihilating each other is meek as they embark opposite ways in a vast universe ...

In the context of general relativity there is no "opposite direction" during the big bang where the anti-matter could have gone.

[Chris Peterson]

we know that matter and anti matter particles were created in equal quantities in bigbang.

We don't know that, we just believe it to be the case based on our current understanding (which isn't great for the instant of the Big Bang or shortly after).

we also know that when they are created they go on on opposite directions.so could there be an antimatter side of universe like matter dominated area.chances of them annihilating each other is meek as they embark opposite ways in a vast universe ...

If the mechanism that created matter resulted in matter/antimatter particle pairs moving in opposite directions, that wouldn't imply any spatial separation of the two in bulk quantities, since each "creation point" would likely have an arbitrary orientation.

The consensus is that we live in a Universe without a significant amount of primordial antimatter because even the tiniest imbalance in quantity or density of matter and antimatter would have quickly resulted in the near complete loss of one or the other (antimatter in the case of our universe). Making the numbers work remains a topic of research, however.

[neufer]

<<In 1967, Andrei Sakharov proposed a set of three necessary conditions that a baryon-generating interaction must satisfy to produce matter and antimatter at different rates. These conditions were inspired by the recent discoveries of the cosmic background radiation and CP-violation in the neutral kaon system. The three necessary "Sakharov conditions" are:

• Baryon number B violation.
  
  C-symmetry and CP-symmetry violation.
  
  Interactions out of thermal equilibrium.

Baryon number violation is obviously a necessary condition to produce an excess of baryons over anti-baryons. But C-symmetry violation is also needed so that the interactions which produce more baryons than anti-baryons will not be counterbalanced by interactions which produce more anti-baryons than baryons. CP-symmetry violation is similarly required because otherwise equal numbers of left-handed baryons and right-handed anti-baryons would be produced, as well as equal numbers of left-handed anti-baryons and right-handed baryons. Finally, the interactions must be out of thermal equilibrium, since otherwise CPT symmetry would assure compensation between processes increasing and decreasing the baryon number.

Currently, there is no experimental evidence of particle interactions where the conservation of baryon number is broken perturbatively: this would appear to suggest that all observed particle reactions have equal baryon number before and after. Mathematically, the commutator of the baryon number quantum operator with the (perturbative) Standard Model hamiltonian is zero: [B,H] = BH - HB = 0. However, the Standard Model is known to violate the conservation of baryon number non-perturbatively: a global U(1) anomaly. Baryon number violation can also result from physics beyond the Standard Model (see supersymmetry and Grand Unification Theories).

The second condition — violation of CP-symmetry — was discovered in 1964 (direct CP-violation, that is violation of CP-symmetry in a decay process, was discovered later, in 1999). Due to CPT-symmetry, violation of CP-symmetry demands violation of time inversion symmetry, or T-symmetry.

In the out-of-equilibrium decay scenario, the last condition states that the rate of a reaction which generates baryon-asymmetry must be less than the rate of expansion of the universe. In this situation the particles and their corresponding antiparticles do not achieve thermal equilibrium due to rapid expansion decreasing the occurrence of pair-annihilation.>>

[ritwik]

i actually thought like you people ...but if you take a moment to read this stuff on CERN website http://public.web.cern.ch/public/en/Res ... on-en.html you might doubt your own understanding.These are people carrying out experiments like LHC and stuff so that give some credence to what they publish on their website and they are not saying it like just one plausible assumption

i'm asking if that is the case, then how could particle & anti particle annihilation take place ..they are saying 100% of antimatter created during BB was annihilated with matter and left over is just 1% of matter with which the whole stars and stuff is evolved,they have a Power point presentation of this ( mother of all conundrums)http://education.web.cern.ch/education/ ... plans.html

how could all these infinitesimally small particles created at BB going at light speed in straight line come together to build atoms

second question intriguing me is how all anti matter particles created completely annihilate with matter particles...even in controlled collisions take place in particle accelerators physicist rely on probability only few protons collide with other so how could in the vastness of open space all these stuff magically come together to annihilate each other

each "creation point" would likely have an arbitrary orientation

i don't really understand by 'each creation point" as i'm not well-versed in physics im asking out of curiosity

doe it mean random excitation of some primordial quantum field thus particles popping out in different directions...

[Chris Peterson]

how could all these infinitesimally small particles created at BB going at light speed in straight line come together to build atoms

Most baryonic particles were going MUCH less than c.

second question intriguing me is how all anti matter particles created completely annihilate with matter particles...even in controlled collisions take place in particle accelerators physicist rely on probability only few protons collide with other so how could in the vastness of open space all these stuff magically come together to annihilate each other :?:

What "vastness" are you talking about? This occurred when the Universe was still small, and the matter that formed was best described as a fluid. Matter density was very high at that time.

i don't really understand by 'each creation point" as i'm not well-versed in physics im asking out of curiosity

I just mean that at every point where a matter/antimatter pair was produced, there would be no preferential orientation. So you don't end up with all the bulk matter going one way and antimatter the other. You have a cloud of both kinds of particles going in all directions. It is in this soup of particles that the annihilation occurs.

[ritwik]

What "vastness" are you talking about? This occurred when the Universe was still small, and the matter that formed was best described as a fluid. Matter density was very high at that time.

do you believe in bigbang predictions that 1. 'space and time' itself was created 2.and universe itself expanded exponentially from a incredibly dense state denser and smaller than the nucleus of an atom

if universe expanded from a spatially bound dense state..does it imply universe is still finite and spatially bound on large scale..

[Chris Peterson]

do you believe in bigbang predictions that 1. 'space and time' itself was created 2.and universe itself expanded exponentially from a incredibly dense state denser and smaller than the nucleus of an atom

I don't like the word "believe" in this context. I think what you describe is the best supported theory we currently have.

if universe expanded from a spatially bound dense state..does it imply universe is still finite and spatially bound on large scale..

Probably, but not certainly.

[Markus Schwarz]

i actually thought like you people ...but if you take a moment to read this stuff on CERN website
http://public.web.cern.ch/public/en/Res ... on-en.html you might doubt your own understanding.These are people carrying out experiments like LHC and stuff so that give some credence to what they publish on their website and they are not saying it like just one plausible assumption

This so called CP-violation, a breakdown of the symmetry between particles and anti-particles, is the process I mentioned earlier. There is also good reason to believe that Time-symmetry is broken as well. The opening sentence of the CERN site is the usual phrasing that you get on general-public sites, so don't take it literary. As said, it is a common and plausible assumption.

i'm asking if that is the case, then how could particle & anti particle annihilation take place ..they are saying 100% of
antimatter created during BB was annihilated with matter and left over is just 1% of matter

This is the million dollar (Nobel) prize question!

[ritwik]

i'm asking if that is the case, then how could particle & anti particle annihilation take place ..they are saying 100% of
antimatter created during BB was annihilated with matter and left over is just 1% of matter

This is the million dollar (Nobel) prize question!

what do you say to the opinion that universe was tinier at the times of matter antimatter creation,thus annihilation is understandable

[Markus Schwarz]

i'm asking if that is the case, then how could particle & anti particle annihilation take place ..they are saying 100% of
antimatter created during BB was annihilated with matter and left over is just 1% of matter

This is the million dollar (Nobel) prize question!

what do you say to the opinion that universe was tinier at the times of matter antimatter creation,thus annihilation is understandable

The question is not why matter and anti-matter annihilated. Assuming they were present with the same amount initially, the question is why 1% matter was left over. We know of processes that distinguish between matter and anti-matter, but these known effects don't give the right amount of matter.

[ritwik]

The question is not why matter and anti-matter annihilated. Assuming they were present with the same amount initially, the question is why 1% matter was left over. We know of processes that distinguish between matter and anti-matter, but these known effects don't give the right amount of matter.

i see...so the question is why we cant see our antimatter neighborhood of cosmos it make sense..but how far we can see the cosmos to say it for certain is ponderable



thanks,

[Chris Peterson]

i see...so the question is why we cant see our antimatter neighborhood of cosmos :ssmile: it make sense..but how far we can see the cosmos to say it for certain is ponderable

That's not really the question. It is possible that there are antimatter regions in the Universe, but there's no evidence of them, and most cosmologists think there are not... because a tiny initial imbalance resulted in the annihilation of all antimatter. One of the biggest questions in cosmology is what caused that imbalance.

[ritwik]

That's not really the question. It is possible that there are antimatter regions in the Universe, but there's no evidence of them, and most cosmologists think there are not... because a tiny initial imbalance resulted in the annihilation of all antimatter. One of the biggest questions in cosmology is what caused that imbalance.

i beg to differ

i don't want to think there was an imbalance..physics could not be wrong ..A-M could be there lurking in the vastness of universe far beyond our imagination ..we might see during Big Crunch

[Chris Peterson]

i don't want to think there was an imbalance..physics could not be wrong ..A-M could be there lurking in the vastness of universe far beyond our imagination

That's what I said.

we might see during Big Crunch

The evidence is now strongly supporting the idea that the expansion of the Universe is accelerating. A Big Crunch is unlikely.

[Ann]

Chris wrote:

The evidence is not strongly supporting the idea that the expansion of the Universe is accelerating. A Big Crunch is unlikely.

You mean that the evidence is now strongly supporting the idea that the expansion of the Universe is accelerating, don't you, Chris?

Ann

[Chris Peterson]

Chris wrote:

The evidence is not strongly supporting the idea that the expansion of the Universe is accelerating. A Big Crunch is unlikely.

You mean that the evidence is now strongly supporting the idea that the expansion of the Universe is accelerating, don't you, Chris?

I do indeed mean that, and have edited my original post. Thanks for catching that.

[Beyond]

I hope the cosmos cops don't give the universe a ticket for speeding.