My question/thought is this... We know gravity is related to matter, could dark matter have "anti-gravity" Just like magnets have different polarities, one to attract and one to repel, could gravity have similar properties that we are unable to identify, perhaps related to types of matter or energy that we cannot identify, yet? This is a question I thought of while pondering the mysteries of the expanding universe and I thought that gravity is the only force that can affect things on such a huge scale, but since it is expanding and not contracting I thought maybe there could be a type of gravity with an opposite "charge". I also wondered if gravity could be the contributor so I will also ask could there have been other big bangs all throughout an infinite universe and our observable universe is being pulled by those other hyperclusters of galaxies, I don't know what else to call the sum of matter created by a big bang, and they are too far away for their light to reach us? And if the gravity from something is reaching another object does that mean its light should reach it as well? Meaning that gravity works at the speed of light?