Originally posted by twhitehead
[b]For an event to be possible in this universe it must have a probability of occurring > 0
I disagree. Give an argument as to why it must have such a non-zero probability of occurring.
Suppose a finite universe were empty of matter. Would an atom in such a universe be said to be impossible? If so, then your definition of 'possible' simply means 'it exists' and your whole claim is a tautology.[/b]
I don't think there is such an argument.
Let S represent the sample space of an experiment, which is the set of all possible outcomes the experiment may yield. An event E is a subset of S. The elements of E are said to be the outcomes of the experiment that are "favorable" to the event in question occurring. If the experiment consists of rolling a six-sided die, then S={1,2,3,4,5,6}. An event E might be the event of rolling an even number, so E={2,4,6}.
Let n(S) denote the number of elements in S, and n(E) the number of elements in E. In the case when S is a finite set, the probability of event E occurring is:
P(E) = n(E)/n(S).
If S={1,2,3,4,5,6} and E={2,4,6}, then the probability of rolling an even number with a six-sided die is P(E) = 3/6 = 0.5. Well, that figures!
In the case when S is infinite (whether countably or uncountably infinite), this just breaks down. If, hypothetically, all the counting numbers (1,2,3,&hellip😉 were put into a hat, the probability of drawing the number 9 would have to be said to be zero, based on the definition of probability given above (1 divided by infinity). And yet, a 9 could be drawn!
That's just the way it is. It's one of the reasons I quit studying statistics years ago and switched to pure mathematics.
In any case, if the universe -- if
all universes in a hypothetical multiverse -- are quantized at the smallest scale, then it's fair to say that every physical inquiry is ultimately at most countably infinite (the infinity of the integers). The uncountable infinity of the real numbers (the continuum) is merely a convenient approximation.