'The Universe doesn't have an outside'? The simple finite nature of the universe makes it intrinsically self-evident there '''is''' reality outside the universe. And the reason engineers design pistons with cylinders around them is for the simple fact that advantage can be taken of the gas resistance you mentioned to do a little work (thus reducing that system's energy quotient, BTW, think about it with me here...) The universe has no such 'cylinder-wall', and during any theoretical collapse, would eventually radiate it's energy ''away'' from itself, and any interior radiative pressure in the system would disappear. However, neither of those is the actual point. The universe is ''currently, right now, at this moment''--a '''perfect black-body radiator'''. We don't need to theorize about some elusive universal collapse. The current universe radiates '''''everything'''''. | 'The Universe doesn't have an outside'? The simple finite nature of the universe makes it intrinsically self-evident there '''is''' reality outside the universe. And the reason engineers design pistons with cylinders around them is for the simple fact that advantage can be taken of the gas resistance you mentioned to do a little work (thus reducing that system's energy quotient, BTW, think about it with me here...) The universe has no such 'cylinder-wall', and during any theoretical collapse, would eventually radiate it's energy ''away'' from itself, and any interior radiative pressure in the system would disappear. However, neither of those is the actual point. The universe is ''currently, right now, at this moment''--a '''perfect black-body radiator'''. We don't need to theorize about some elusive universal collapse. The current universe radiates '''''everything'''''. |