Could matter-anti-matter repulsion power the expansion of the universe? (Intermediate)

If matter and anti-matter were created in roughly equal proportions at BB, and their subsequent annihilation did NOT occur, perhaps if the left hemisphere was matter and the right hemisphere were anti-matter, would not the repulsive gravity of the two perhaps power the accelerating status of our "matter universe"? Matched by an equal condition on the anti- side?

No, because there is no repulsive gravity between matter and anti-matter. Anti-matter particles are basically the same as their corresponding matter particles, but they have opposite charge. They still attract each other gravitationally.

But even if matter and anti-matter did repel each other, your scenario still wouldn't work, given the way the universe is expanding. The universe expands such that every point in space is expanding away from every other point in space. Galaxy A is moving away from Galaxy B and Galaxy C, and Galaxy B and Galaxy C are also moving away from each other. If you had two flavors of matter (matter and anti-matter), and they repelled each other, but attracted themselves, then this wouldn't work. It doesn't explain the expansion of the universe as we actually see it.

This page was last updated June 27, 2015.

About the Author

Christopher Springob

Christopher Springob

Chris studies the large scale structure of the universe using the peculiar velocities of galaxies.  He got his PhD from Cornell in 2005, and is now a Research Assistant Professor at the University of Western Australia.

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