How much energy is there in the universe? I've heard a lot of people saying the total amount of energy in the universe is 0, if this is the case the total amount of mass in the universe is 0. In this scenario there is an equal and opposite amount of mass/energy in the universe. How would the "negative" mass/energy act? It would need to be something when brought in contact with "positive" mass/energy would exactly annihilate each other and bring the system back to a state of 0 (with no "positive" or "negative" fluctuations). Do we see anything of this nature? Upon first look it seems like a weird concept both required and disallowed by the laws of physics, but I have the sense that I'm just not look at it from the right perspective yet. Thanks for your help!