-The 'big thinking': since our age is that of 'deep space exploration' and colonization of the habitable exoplanets.
-According to Bunge (one of the grand systemtheorist): the universe is a system. But it does not have an environment.
-Well, this is against the argument of Herb Simon (the Nobel laureate and systemtheorist; see my previous question!).
-What is your answer? or argument(s)? Thanks, Marc
Hi, first of all it is primordial to define what a system is. If you consider that a system is a set of elements in interaction, it's seems obvious that the answer is yes. If you add other constraints, which ones? Also, all the elements of our universe are also in a space-time that could be interpreted as an environment. So, all the terms have to be defined properly to answer to this question adequately :-)
The universe as a whole might be a closed system if the classical view that it is "all that exists" is true. However, if the hypothesis that there may be other universes within a multiverse is correct, then those universes and ours exist within the environment of a false vacuum, possibly undergoing eternal inflation.
Within our universe we could however treat the "observable universe" as a system if the hypothesis of dark energy or a Cosmological Constant is correct, those create a cosmological event horizon and parts of the universe beyond that can never affect us without violating causality.
The universe started in the Big Bang and what is visible to us is absolutely gargantuan - in the order of 100 billion galaxies each with 100 billion suns (a very rough estimate). But this is only a portion of the universe, the limits on our ability to see further being imposed by the finite speed of light. We can tell that there is more out there beyond our visual horizon because some galaxies on the fringes are being pulled by the gravity of objects further out. Given that it is so incredibly large, it may well go on forever. But how could this be so?
Firstly ignore the question of multiverses, pocket universes and the like, because they are very speculative. Our own Universe looks very much like one that created itself from nothing. Why? Because gravity and energy, the two components of matter, are like positive and negative charges - one contracts spacetime and the other is spatially expansive and speeds time. Physicists have measured the amount of gravity and energy in the universe and they balance out. So they could easily have been created from nothing in the Big Bang because this would obey the law of conservation of energy. Alan Guth (who originally proposed big bang inflation) is quoted in Stephen Hawking's A Brief History of Time "It is said that there is no such thing as a free lunch. The Universe is the ultimate free lunch."
Also, if the Universe didn't start from nothingness, then how did it start? While many people might like to propose some preexisting state or entity, such as God or a quantum field or cyclic universe, these situations always prompt the question - "But why the prior existence of God/quantum/cyclic universe? How was that created?" So if we take it that the starting point was nothingness, then the question "How could the universe be infinite?" is easy. It could be infinite because there is no limit to the amount of nothingness one could have. In particular, if we are truly starting with nothingness, then how COULD it have any kind of boundary or limit?
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