"That the cosmos is a computer sounds like a modern metaphor, a way of explaining how things work. But some make a bolder claim: that the cosmos is in reality a computer, not just as metaphor. This would mean that all that exists in the physical universe is in essence the computational process of the universe itself generating itself. Does that make sense?"
 
Yes & No is the answer of Leonard Susskind. We can see the universe as a message, a message of information represented exactly like the Morse Code, dots and dashes, binary code, whatever. 
 
If that makes sense to say we live in a simulation, it's also a contradiction according to the theory of black holes, now a reality! He suggests that the volume of information of these dots and dashes (exactly like black holes) is proportionate not to the volume of the universe but to the surface area of its boundaries, making it a hologram.
 
That kind of message though, together with the fact that our brain is not constructed to understand it and we have to invent abstract mathematics, makes sense to say that current human laptop technology may not be the right equivalent to describe it, hence cosmos is not a computer, at least in any kind of human understanding...