3 ms·

Some examples: Matter/anti-matter asymmetry, arrow of time direction, why CP violations, neutrino mass questions, why masses are what they are, dark matter and

Some examples: Matter/anti-matter asymmetry, arrow of time direction, why CP violations, neutrino mass questions, why masses are what they are, dark matter and energy nature, what cancels out zero point energy, many structures on universe scale don't fit models, firewall paradox, why is gravity so weak, are there gravitons (other particles..), do magnetic monopoles exist (widely conjectured to work from models, none yet seen), why 3 generations of particles, proton radius discrepancies, exotic and pentaquark (and higher) particles, Navier-Stokes open problems, lots of superconductor and metamaterial questions results not explained theoretically, and so on...

nonbel 7y ago
Matter/anti-matter asymmetry is expected to be present. It is a basic feature of individual random walk instances using symmetrical laws that about half will be dominated by matter and the other half dominated by antimatter for long periods of time (although the "universe" may pass through pure energy states as it switches between the two). While there is a balance on average and in the long run, there is not for individual instances or points in time. We called the dominating one for our current instance/state of the universe "matter": https://physics.stackexchange.com/questions/505662/why-is-matter-antimatter-asymmetry-surprising-if-asymmetry-can-be-generated-by https://physics.stackexchange.com/questions/505662/why-is-ma...
- ChrisLomont 7y ago
  >Matter/anti-matter asymmetry is expected to be present. It is a basic feature of individual random walk It may be the cause, but it is not known to be the cause. And it's not a random walk; black holes accumulate charge from pairs, making future radiation not symmetric. My understanding is that people have probed this for some time and it's still inconclusive if it can generate the observed imbalance. Here's [1] a 1979 paper on the idea, with hundreds of citations, in case you want to poke at the literature. If I remember, Cosmology by Weinberg has a chapter on various theories of how the imbalance may happen, none of them known to be all of or even part of the answer. [1] https://journals.aps.org/prd/abstract/10.1103/PhysRevD.19.1036 https://journals.aps.org/prd/abstract/10.1103/PhysRevD.19.10...
  - nonbel 7y ago
    Nice link, thanks.

nonbel 7y ago

Matter/anti-matter asymmetry is expected to be present. It is a basic feature of individual random walk instances using symmetrical laws that about half will be dominated by matter and the other half dominated by antimatter for long periods of time (although the "universe" may pass through pure energy states as it switches between the two). While there is a balance on average and in the long run, there is not for individual instances or points in time. We called the dominating one for our current instance/state of the universe "matter": https://physics.stackexchange.com/questions/505662/why-is-matter-antimatter-asymmetry-surprising-if-asymmetry-can-be-generated-by https://physics.stackexchange.com/questions/505662/why-is-ma...

ChrisLomont 7y ago
>Matter/anti-matter asymmetry is expected to be present. It is a basic feature of individual random walk It may be the cause, but it is not known to be the cause. And it's not a random walk; black holes accumulate charge from pairs, making future radiation not symmetric. My understanding is that people have probed this for some time and it's still inconclusive if it can generate the observed imbalance. Here's [1] a 1979 paper on the idea, with hundreds of citations, in case you want to poke at the literature. If I remember, Cosmology by Weinberg has a chapter on various theories of how the imbalance may happen, none of them known to be all of or even part of the answer. [1] https://journals.aps.org/prd/abstract/10.1103/PhysRevD.19.1036 https://journals.aps.org/prd/abstract/10.1103/PhysRevD.19.10...
- nonbel 7y ago
  Nice link, thanks.