As I see it, there is indeed a "tension" between our intuition about the nature of reality and the idea of a past without a beginning. It may be worth looking into the question.
Contrary to what UM claims, however, I don't see how the idea of a past with no beginning would be illogical.
His argument, I guess, is to ask us to try and imagine something "traversing" the entire infinity of the past to get to the present moment, and admit that we can't do that. Obviously, it's true that we can't do that. Yet, this in itself is no proof that the idea of time with no beginning is illogical. It's just evidence of the limited capacity of our brains, and indeed, we can assume, of any real thinking system.
Still, it's interesting to look more closely at our intuition about causality.
My assumption here about our intuition concerning causality is that if there is something now, it's because there was something else immediately before that physically caused it to come about. Potentially, if true, this would in fact require some kind of temporal infinity. I assume here there's essentially only two kinds of infinity. Either there was an infinite past (discrete time analogous to N), or, if the past was finite and had therefore a beginning, time must be infinitely divisible so as to allow an infinity of causal reactions to take place within a finite period of time (continuous time analogous to R+).
If we assume time had no beginning, we're left with only the first option (analogy to N).
In this case, could anything have traversed the infinity of the past so as to exist now? Obviously, we're no talking about people. Not even about any kind of administrative body or institution powered by a human workforce, generation after generation. However, the idea of causality itself does amount to having something like a unified body, not so different from that of an organism, going through the length of time, and therefore a "body" which at any point in time would have already been in existence for an infinite amount of time. A succession of Big Bangs, and therefore a succession of universes, one following another, endlessly and without a beginning to the succession, and each Big Bang caused by the previous universe (if we want to assume an unbroken causal chain), would amount to such a unified body persisting through an infinite time, a time without an end but also without a beginning. In that perspective, can we really conceive of such a unified body subject to an evolutionary process, like every macroscopic thing we know of in our universe? Can we conceive of just one body unified by causality, but continuously evolving so as to have a structure and organisation unique to each moment in time? Again, there's no logical contradiction in that idea but I think we can't conceive of possibility, again because our brain couldn't possible harbour an infinity of such unique organisations and structures and we only ever think of finite sets. So instead, we can fall back on the idea of Big Bang and conceive of a fundamentally cyclical reality, with a succession of universes which may or may not be identical to each other, but with overall only a finite number of types of universe. That, we can conceived of.
So, what would be the problem with a reality made of a succession of essentially identical universes, the disappearance of one causing the appearance of a new, but essentially identical universe? Would that idea contain some kind of logical contradiction? Personally, I don't see why that would be the case. In fact, I'm very confident that very nearly all scientists would agree with me on this. Obviously, this would be a very simple form of infinity, all universes being essentially identical to each other, or each belonging to an infinite set of strictly identical universes, with overall a finite number of types of universes. Either way, we would end up with the history of successive universes repeating itself at some point in time, and again, and again, for ever.
You're all welcome to comment on this particular point.
Another possible conception of reality is the idea of a succession of universes without a relation of causality between different universes. Each universe would just pop up on its own, uncaused, and unrelated in any way to any other universe. I think it's one possibility, yet I would dismiss this case as irrelevant to the question of the infinity of the past. If universes can exist wholly independently of each other, then the notion of time just disappears, or, more accurately, time becomes something restricted to each universe, starting with the Big Bang and stopping whenever the universe disappears. There would be no time encompassing all universes, and therefore no need for an infinite time. Obviously, again, I think that's a conception we would have a hard time accepting. Personally, I seem unable to imagine a such a possibility. Still, I don't see where there would be any logical contradiction in this case.
I guess some may also want to comment on this.
EB
Yes? So, here it is again, in extenso, just for your consideration.
As I see it, there is indeed a "tension" between our intuition about the nature of reality and the idea of a past without a beginning. It may be worth looking into the question.
Contrary to what UM claims, however, I don't see how the idea of a past with no beginning would be illogical.
His argument, I guess, is to ask us to try and imagine something "traversing" the entire infinity of the past to get to the present moment, and admit that we can't do that. Obviously, it's true that we can't do that. Yet, this in itself is no proof that the idea of time with no beginning is illogical. It's just evidence of the limited capacity of our brains, and indeed, we can assume, of any real thinking system.
Still, it's interesting to look more closely at our intuition about causality.
My assumption here about our intuition concerning causality is that if there is something now, it's because there was something else immediately before that physically caused it to come about. Potentially, if true, this would in fact require some kind of temporal infinity. I assume here there's essentially only two kinds of infinity. Either there was an infinite past (discrete time analogous to N), or, if the past was finite and had therefore a beginning, time must be infinitely divisible so as to allow an infinity of causal reactions to take place within a finite period of time (continuous time analogous to R+).
If we assume time had no beginning, we're left with only the first option (analogy to N).
In this case, could anything have traversed the infinity of the past so as to exist now? Obviously, we're no talking about people. Not even about any kind of administrative body or institution powered by a human workforce, generation after generation. However, the idea of causality itself does amount to having something like a unified body, not so different from that of an organism, going through the length of time, and therefore a "body" which at any point in time would have already been in existence for an infinite amount of time. A succession of Big Bangs, and therefore a succession of universes, one following another, endlessly and without a beginning to the succession, and each Big Bang caused by the previous universe (if we want to assume an unbroken causal chain), would amount to such a unified body persisting through an infinite time, a time without an end but also without a beginning. In that perspective, can we really conceive of such a unified body subject to an evolutionary process, like every macroscopic thing we know of in our universe? Can we conceive of just one body unified by causality, but continuously evolving so as to have a structure and organisation unique to each moment in time? Again, there's no logical contradiction in that idea but I think we can't conceive of possibility, again because our brain couldn't possible harbour an infinity of such unique organisations and structures and we only ever think of finite sets. So instead, we can fall back on the idea of Big Bang and conceive of a fundamentally cyclical reality, with a succession of universes which may or may not be identical to each other, but with overall only a finite number of types of universe. That, we can conceived of.
So, what would be the problem with a reality made of a succession of essentially identical universes, the disappearance of one causing the appearance of a new, but essentially identical universe? Would that idea contain some kind of logical contradiction? Personally, I don't see why that would be the case. In fact, I'm very confident that very nearly all scientists would agree with me on this. Obviously, this would be a very simple form of infinity, all universes being essentially identical to each other, or each belonging to an infinite set of strictly identical universes, with overall a finite number of types of universes. Either way, we would end up with the history of successive universes repeating itself at some point in time, and again, and again, for ever.
You're all welcome to comment on this particular point.
Another possible conception of reality is the idea of a succession of universes without a relation of causality between different universes. Each universe would just pop up on its own, uncaused, and unrelated in any way to any other universe. I think it's one possibility, yet I would dismiss this case as irrelevant to the question of the infinity of the past. If universes can exist wholly independently of each other, then the notion of time just disappears, or, more accurately, time becomes something restricted to each universe, starting with the Big Bang and stopping whenever the universe disappears. There would be no time encompassing all universes, and therefore no need for an infinite time. Obviously, again, I think that's a conception we would have a hard time accepting. Personally, I seem unable to imagine a such a possibility. Still, I don't see where there would be any logical contradiction in this case.
I guess some may also want to comment on this.
EB
I provided the explanation but understanding is something you have to do by yourself.
Just try harder.
EB
The same is true of the zygote immediately after fertilization. Your position here is purely arbitrary.
Not after, either. A single cell is not a human. A blastula is not a human. A fetus is not a human. Your objection applies as much to your position as to mine; It is irrational and stupid.
