Actual Infinity in Reality?

[SteveII]

Your very sentence "Where is the impossibility of having infinitely many precursors?" contains the metaphysical impossibility. It's that simple. You will never get to the present because there are always and infinite amount of precursors that still need to happen to get to the present. 


I have no idea where you are getting these infinite gaps I supposedly am proposing. Your theory has events every moment in time going back. I am talking about the same scenario. I am not talking about a start to such a sequence either for your scenario. The fact that you have no start is the problem that creates the metaphysical impossibility. You cannot have a sequence of events ending today because there will always have to have happened a infinite amount of sequences before you get today. You will never get to today. Ever. I don't know how to say it any clearer.  

Notice how Grnadizer gets this. However, he is trying to solve it by saying there are no sequences that have to happen because there is no such thing as cause/effect. So he is not arguing for an actual infinity of events. He says there are just no events.

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Then this should be easy to show me shouldn't it! Abstract uncountable potentially infinite sets are useful on paper. Show me in mathematics where an infinite set has no beginning. Only that would be an actual infinite in mathematics. If you can only find sets with a beginning, all you are talking about is potential infinite sets. Apples and oranges. 

They do not translate to the real world. You three are hiding behind this leap. I challenge any of you to find a paper that describes how an actual infinite is possible.

Okay, I think I finally understand your objection here.  You’re saying that time-flow is what’s throwing a wrench into translating an actual infinite from math to reality.  I get what you mean, but I am no physicist so I’ll let Grand and Poly continue on.  However I will say, as Grand has said, I don’t see how an actual infinity wouldn’t be logically possible if we assume B theory of time is correct.  Directionality of time wouldn’t be an issue in that case, if my understanding of the theory is correct.

First, I don't think the B Theory of Time is correct. But leaving that aside for now, the B Theory of Time holds that all past, present and future time slices are all real simultaneously in a four dimensional spacetime manifold. Our current universe's physical laws govern this manifold so this manifold is only as old as the universe. There is nothing in the theory that claims a past infinite. 

The past infinite claim is derived from either a cosmology model, just accepting it as a brute fact (no explanation that could be forthcoming), or just asserting it must be so. The eternal universe models are not the most popular models because they lack components or plug values. The data that keeps coming in suggests a Big Bang-type model. 

Grand seems to see the problem of a past infinite series of cause/effects is metaphysically impossible--that's why he is claiming there is no such thing as a cause/effect so there are not an infinite amount of events/relationships to trigger the logic. 

But even if he believes there are not causes/effects in our spacetime manifold, a Big Bang-type model indicates a beginning of our spacetime manifold--a "prior to" if you will. If spacetime manifolds can begin, then even if we guess at a multiverse theory, we have established cosmic cause/effect -or to say it another way, was contingent upon the previous state. We can run these states back into infinity and we get the same problem--if there was an infinite amount of events (prior states) in the past, we would never get through them all to get to the event that spawned our universe.

Even if you say "well, then there is a larger B Theory-type spacetime manifold which contains all this", you still have clear "prior to" and "after than" states (cause/effect) that trigger the impossibility of traversing an infinite amount of events to get to our special little slice of infinity--our universe. Because--remember, there is nothing about the B theory of time that implies a past infinite--so simply declaring such a manifold does not get around the problem.