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The issue with the "past the observable universe horizon" is that it is an entirely untestable theory. It may be true, but it may as well be irrelevant because

The issue with the "past the observable universe horizon" is that it is an entirely untestable theory. It may be true, but it may as well be irrelevant because according to our understanding of the universe, we are never going to be affected by this fact (since it's in a part of the universe from which information may never reach us).

kadoban 2y ago
It also answers not much, just changes the question. There's no known reason for all the matter to be over here, where we are, and all of the antimatter to be way over _there_ outside of the observable universe. If anything that seems much less likely than there just being other imbalances in which gets created (or which survives over time, etc.). The universe would have to have preferred absolute directions in which to throw different types of matter/antimatter? That'd be very strange indeed, based on what we know.
- dhosek 2y ago
  Not necessarily—perhaps it’s something like what we have right now is the residue of a slight variation from 50/50 in our local part of the universe (so it might have been 50.01% matter, 49.99% antimatter, and after the bulk of the matter and antimatter interacted and destroyed each other, the observable universe is that .02% left over. Do we know enough to be able to search for evidence of this in the cosmic background radiation?
  - deleted 2y ago
    [deleted]
  - kadoban 2y ago
    My guesses are: A universe that did that would have too much energy (from the mutual annihilation) once the orders and orders of magnitude of "extra" matter/antimatter interacted to make that likely/possible. Wouldn't we also see clouds of antimatter just hanging around? What proportion of matter has ever interacted with anything else? My guess is "low".
- vl 2y ago
  >There's no known reason for all the matter to be over here The problem is there is no known reason for universe to exist. As such it could have been created in any configuration possible - including one where we observe matter, but antimatter is beyond event horizon.
Dalewyn 2y ago
>we are never going to be affected by this fact (since it's in a part of the universe from which information may never reach us). For curiosity's sake: Wouldn't something like quantum mechanics defy that argument?
- semi-extrinsic 2y ago
  Nope, see for instance good explanations in [1] and [2]. The TL;DR is that you can't actually get information out of a measurement of entangled quantum states placed at locations A and B without also transmitting classical information between A and B. But good question! [1] https://en.wikipedia.org/wiki/Quantum_teleportation https://en.wikipedia.org/wiki/Quantum_teleportation [2] https://www.forbes.com/sites/startswithabang/2020/01/02/no-we-still-cant-use-quantum-entanglement-to-communicate-faster-than-light/ https://www.forbes.com/sites/startswithabang/2020/01/02/no-w...

kadoban 2y ago

It also answers not much, just changes the question. There's no known reason for all the matter to be over here, where we are, and all of the antimatter to be way over _there_ outside of the observable universe. If anything that seems much less likely than there just being other imbalances in which gets created (or which survives over time, etc.). The universe would have to have preferred absolute directions in which to throw different types of matter/antimatter? That'd be very strange indeed, based on what we know.

dhosek 2y ago
Not necessarily—perhaps it’s something like what we have right now is the residue of a slight variation from 50/50 in our local part of the universe (so it might have been 50.01% matter, 49.99% antimatter, and after the bulk of the matter and antimatter interacted and destroyed each other, the observable universe is that .02% left over. Do we know enough to be able to search for evidence of this in the cosmic background radiation?
- deleted 2y ago
  [deleted]
- kadoban 2y ago
  My guesses are: A universe that did that would have too much energy (from the mutual annihilation) once the orders and orders of magnitude of "extra" matter/antimatter interacted to make that likely/possible. Wouldn't we also see clouds of antimatter just hanging around? What proportion of matter has ever interacted with anything else? My guess is "low".
vl 2y ago
>There's no known reason for all the matter to be over here The problem is there is no known reason for universe to exist. As such it could have been created in any configuration possible - including one where we observe matter, but antimatter is beyond event horizon.

Dalewyn 2y ago

>we are never going to be affected by this fact (since it's in a part of the universe from which information may never reach us). For curiosity's sake: Wouldn't something like quantum mechanics defy that argument?

semi-extrinsic 2y ago
Nope, see for instance good explanations in [1] and [2]. The TL;DR is that you can't actually get information out of a measurement of entangled quantum states placed at locations A and B without also transmitting classical information between A and B. But good question! [1] https://en.wikipedia.org/wiki/Quantum_teleportation https://en.wikipedia.org/wiki/Quantum_teleportation [2] https://www.forbes.com/sites/startswithabang/2020/01/02/no-we-still-cant-use-quantum-entanglement-to-communicate-faster-than-light/ https://www.forbes.com/sites/startswithabang/2020/01/02/no-w...