How would we know if a distant galaxy is made up of anti-matter instead of normal matter?

Question

One of the big questions in physics I've heard about, is why there is more matter than anti-matter.  If Andromeda was almost completely anti-matter with the same percentage of normal matter in it as the milky way has anti-matter, wouldn't that solve the problem? At the time of the big bang, the pairs of virtual particles just got far enough away from each other and clumped up so they didn't annihilate?

Comments

It’s a fascinating question, especially considering that observational data has not yet detected the expected gamma-ray signatures from matter-antimatter boundaries. 

From the viewpoint of Einstein’s General Relativity, gravity is the curvature (geometry) of spacetime. If we extend this geometric principle to the quantum scale, could we consider that matter and anti-matter are not "independent particles traveling through space," but rather different topological twisting patterns (such as right-handed vs. left-handed geometric resonance) of the spacetime fabric itself?

If we model particles as localized topological states of spacetime, the baryon asymmetry might be explained as a structural phase transition where the global topology of the early universe naturally favored one twisting direction.

By the way, Brian, your premise about macroscopic clusters (like Andromeda) morphing or isolating into distinct domains is a highly engaging perspective. What specific line of thought or physical anomaly led you to this intriguing intuition?

I would love to hear more about your underlying reasoning.

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I came up with idea because we have created anti-mater and kept it from annihilating with normal matter by isolating it. Distant galaxies are also isolated from each other.  In the early universe something caused this isolation, yet it was done in clumps.  If all the mass in the universe was equally clumped, we would have a single black hole, not multiple galaxies with multiple objects in each.

My initial thought was the big bang caused way more matter/anti-matter pairs than we see now. Each pair having a significant amount of energy moving them apart.  But the pairs that ran into their opposites didn't survive, leading to mostly empty space.  The ones that randomly missed any opposing particles got caught up in gravity and became the matter, (or anti-matter) that we can observe.  This works just as well if the matter/anti-mater is a wave pattern in spacetime where constructive and destructive interference can cause what looks like random noise signals to combine into large peaks and valleys in the waveform in one spot and flat spots where they canceled out in other spots.

The extra matter/anti-matter being created then quickly annihilating part of my idea isn't actually required though.  It makes sense to explain why some matter exists, but not a single clump. The initially even momentum of all the particles would lead to uneven clumping if some of them were removed randomly. However uneven initial momentum alone might be enough for that.

Still the base question remains.  Can we tell if a distant object is composed of mater or anti-mater?  Our assumption is that there is more matter than anti-matter in the universe because we almost exclusively interact with mater... but we also haven't interacted with a significant portion of the universe. So that's sample bias.

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Dear Brian,

Thank you for your response.

I deeply admire your analytical insight and your remarkable work in the field. Your profound perspectives on both the double-slit experiment and the nature of antimatter are truly extraordinary.

If you don’t mind, I would love to ask for your perspective on a specific topic. How do you interpret the Ryu-Takayanagi formula, which mathematically demonstrates that the core essence of the universe is information? 

I would be absolutely thrilled to hear your thoughts on this matter.Furthermore, I am highly interested to learn your personal views on the foundational mechanics of the universe, as well as your interpretation of consciousness.

Thank you very much for your time, and I look forward to hearing your insights.