3 ms·

> “According to our understanding of the Standard Model [of particle physics], the Big Bang should have created exactly the same amount of matter and antimatter

> “According to our understanding of the Standard Model [of particle physics], the Big Bang should have created exactly the same amount of matter and antimatter, but [for the most part] only matter remains,” says BASE Spokesperson Stefan Ulmer. This is strange because when matter and antimatter meet, they annihilate one another. Scientists want to know how matter came to dominate our universe. We don't have any evidence that matter DOES dominate the universe. Distant galaxies could easily be composed of antimatter. Since the Big Bang should have created equal amounts of both, you would expect that in the vast majority of cases they would annihilate one another, leading to a universe overwhelmingly dominated by (wait for it) empty space. We have tons of evidence that matter dominates our neck of the woods. Regions where one form is dominant over the other may be in the minority, but you would have to enter such a region to find stars, planets, and galaxies. The fact that we're here means that this must be an area where one type is everywhere and the other is almost completely absent. But as best we can tell, the fact that we're all made of matter rather than antimatter is the result of a very old coin flip. The probability that all of the galaxies we can see landed on the matter side of the coin is infinitesimal.

dwaltrip 9y ago
I'm pretty sure they have very compelling reasons to believe that distant galaxies are NOT made of anti-matter. Here is one I found in a quick search: The boundary between any group of anti-matter galaxies and the region of space where matter is dominant should emit gamma rays, as the intergalactic wind pushes dust particles made of regular matter into one of the anti-matter galaxies. We don't see such gamma ray emissions in our observations of the cosmos. Source: https://www.forbes.com/sites/briankoberlein/2016/12/27/could-some-distant-galaxies-be-made-of-antimatter/ https://www.forbes.com/sites/briankoberlein/2016/12/27/could...
- philipov 9y ago
  What if all the antimatter-dominated regions are outside our cosmological horizon and are no longer in causal contact with matter-dominated regions?
  - Retric 9y ago
    That just creates the same questions for why this region of space is so dominated by 'matter' while adding a new one that another vast region of space is dominated by 'anti-matter'. If you can come up with some compelling mechanism for it then sure it may be possible, but currently that seems to be more complex and fails to provide any support of any kind.
    - philipov 9y ago
      It's pure speculation, but I am suggesting that instead of some sort of annihilation imbalance, the mechanism might be a sorting process that causes antimatter and matter to collect into horizon-shaped pockets. If there were such a sorting process that was inherently linked to cosmological horizons, it could explain both where the antimatter went, and why we don't see an annihilation zone where the boundaries meet.
      - platz 9y ago
        Unfortunately one can use the anthropic principle to say anything about science beyond the horizon, since anything beyond the horizon is unobservable
      - Retric 9y ago
        The problem is your sorting process is identical to your original statement. It's like saying "why is the sky blue" > "air is blue". You need to make predictions that are different from your observations. On the other hand if you say something like "Air becomes blue when it's colder." Then you can actually test what's going on and falsify the statement which may lead to progress. Suppose you suggest the output of this experiment will change over time. Now, waiting a billion years is not going to happen but adding even more digits of accuracy may be possible.
- excalibur 9y ago
  Thanks for doing my research for me. This is why you should always google before you post :) I could edit my original comment to be more accurate and make a more limited point, but it's probably best to let it stand as-is, for anyone else who may have similar thoughts.
csomar 9y ago
Are you a physicist with 20 year of career? Otherwise, I'll steer away from having strong opinions and just listen to what they are saying. The reason: They probably know better than you and not just making an "assumption". For example, I used to think that they were "speculating" about the big bang happening and the formation of the universe. Until I learned about the Cosmic Microwave background. These guys know better than making wild guesses.

dwaltrip 9y ago

I'm pretty sure they have very compelling reasons to believe that distant galaxies are NOT made of anti-matter. Here is one I found in a quick search: The boundary between any group of anti-matter galaxies and the region of space where matter is dominant should emit gamma rays, as the intergalactic wind pushes dust particles made of regular matter into one of the anti-matter galaxies. We don't see such gamma ray emissions in our observations of the cosmos. Source: https://www.forbes.com/sites/briankoberlein/2016/12/27/could-some-distant-galaxies-be-made-of-antimatter/ https://www.forbes.com/sites/briankoberlein/2016/12/27/could...

philipov 9y ago
What if all the antimatter-dominated regions are outside our cosmological horizon and are no longer in causal contact with matter-dominated regions?
- Retric 9y ago
  That just creates the same questions for why this region of space is so dominated by 'matter' while adding a new one that another vast region of space is dominated by 'anti-matter'. If you can come up with some compelling mechanism for it then sure it may be possible, but currently that seems to be more complex and fails to provide any support of any kind.
  - philipov 9y ago
    It's pure speculation, but I am suggesting that instead of some sort of annihilation imbalance, the mechanism might be a sorting process that causes antimatter and matter to collect into horizon-shaped pockets. If there were such a sorting process that was inherently linked to cosmological horizons, it could explain both where the antimatter went, and why we don't see an annihilation zone where the boundaries meet.
    - platz 9y ago
      Unfortunately one can use the anthropic principle to say anything about science beyond the horizon, since anything beyond the horizon is unobservable
    - Retric 9y ago
      The problem is your sorting process is identical to your original statement. It's like saying "why is the sky blue" > "air is blue". You need to make predictions that are different from your observations. On the other hand if you say something like "Air becomes blue when it's colder." Then you can actually test what's going on and falsify the statement which may lead to progress. Suppose you suggest the output of this experiment will change over time. Now, waiting a billion years is not going to happen but adding even more digits of accuracy may be possible.
excalibur 9y ago
Thanks for doing my research for me. This is why you should always google before you post :) I could edit my original comment to be more accurate and make a more limited point, but it's probably best to let it stand as-is, for anyone else who may have similar thoughts.

csomar 9y ago

Are you a physicist with 20 year of career? Otherwise, I'll steer away from having strong opinions and just listen to what they are saying. The reason: They probably know better than you and not just making an "assumption". For example, I used to think that they were "speculating" about the big bang happening and the formation of the universe. Until I learned about the Cosmic Microwave background. These guys know better than making wild guesses.