Sorry, I don’t follow what you mean. Please elaborate.
Entropy would in no way prevent space from being infinite, for example.
Because the second law (of thermodynamics, I’m assuming) doesn’t define entropy, but rather it’s affect.
Well, a full statement of the 2nd law would include the definition of all the terms used, but the point was why eliminate the formal definition - the only ‘true’ one from the point of view of the physics - and concentrate on the arm-waving common english definition, which is only an approximation. I’m probably being a math snob, in other words.
But actually, a more fundamental issue here is that you are talking about why
physical laws make infinite past time (allegedly) impossible. Surely the original question was why infinite past time would be
logically impossible?
However, I reject their assertion that there could be an infinite past.
On physical or logical grounds? The entropy argument you gave above is a purely physical argument, but below you seem to be making something more like the contingency argument.
What they are proposing is a causality loop (I don’t remember the technical name for it, sorry) wherein the cause of an event is contained within its affect.
I think some ‘oscillating universe’ theories
would count as a causal loop, in that the Big Bang that happens after the Big Crunch is the same every time. But that is not the only possibility, and I
think it is absolutely ruled out in the bubble universe theories.
Again, I would like to differentiate two different classes of logical arguments about causality:
A) If you draw a map of causes and effects, each cause/effect being a point and an arrow going from a cause to its effects, you have what mathematicians (and IT blokes) call a
directed graph. You can draw a lot of conclusions about such graphs without even knowing if they represent cause-and-effect or information flow in a network or something else, just on how it is logically possible to link up points.
For example if you allow only a finite number of nodes (causes/effects) and do not allow directed loops (where you can go around following the direction of the arrows and get back to your start point) you have a
finite directed acyclic graph, where it is trivial to show that you must have at least one node with no arrows going to it, a.k.a. an uncaused cause.
This is one class of argument, that is based purely on the logic of how you can possibly link up nodes, given certain rules such as “no loops”.
B) Another class of argument is based on the rules themselves.
For example, if “a finite number of nodes” is not a rule, there is no reason why we cannot have an infinite chain of cause/effect ‘nodes’ with no uncaused cause. Just label each node with an integer (including negatives) and each node ‘N’ is caused by ‘N-1’ and causes ‘N+1’.
Likewise if loops are allowed, A->B->C->A is a simple graph with no uncaused cause (depicted at the top of the
directed graph wikipaedia page I linked).
If your response is that that is impossible, not because you don’t think loops are possible
per se but for some other reason, you are effectively adding a rule that there must be an uncaused cause. So your
real argument is not about how you can link up nodes in such a manner, but whatever makes you assert that A->B->C->A must have an underlying uncaused cause.
So, is your argument about how cause/effects can be linked up logically, as in a directed graph, or that you think an uncaused cause is a necessary inclusion for some other reason (e.g. contingency)?
DrTaffy;10802988:
ProdglArchitect;10802625:
Anything which is infinite cannot have a beginning.
For example, the set of positive integers [1,2,3,4,5…] is infinite, yet has a beginning.
Umm… 1 is your beginning, or zero, depending on if you consider it positive or not; personally I do, so my beginning would be zero.
Fine, whichever. But you still have an infinite ‘thing’ with a beginning. Time, for example, could have a beginning (Big Bang) and still be infinite into the future.
Also, unless you pick a base point from which to count, the numbers serve no purpose and have no meaning; similarly, unless you pick a point from which to define the “start” of time, time is meaningless.
I don’t see why. Even in an infinite series of events, duration and the seperation in time between events would have meaning, even if the ‘origin’ (the time T=0) of any temporal coordinate system might be purely arbitrary, but not necessarily even that.
You stated the age of the universe, that is not an infinite number, large may be but not infinite.