In effect it always seems reasonable to ask, for any posited beginning of time itself, for a time before that beginning. This leads to an infinite regress - for any beginning of time we can always ask for a time before that purported beginning. This then implies that to say time had a beginning is nonsensical. It (time) can't have a beginning. So, if time has no beginning, is the past infinite? — TheMadFool
I don't think it is reasonable to say time had a beginning, and then speculate on how we deal with time before that. If time began with the Big Bang, then the concept of time before it is nonsensical, and can't be palmed off as 'infinite'. Whatever existed before the Big Bang (even assuming the concept of 'existance' is any more valid than 'time' to describe it) time wasn't part of it. Even that statement is absurd, because there is no 'before' the Big Bang.
We poor humans don't have the brains or language to deal with this problem! — Tim3003
Why is it "nonsensical" to say ask of time before the Big Bang? What is particularly "nonsensical" about it? Does it lead to a contradiction? How? Where? — TheMadFool
If you're saying time began with the Big Bang surely you can't talk about time before the Big Bang - any more than you can talk about what's north of the North Pole. 'Northness' starts with the Pole. If you're saying time existed before the Big Bang it's a different question. So you have to decide which route to go down as the Big Bang theory has to differ according to your choice.. — Tim3003
The problem with an infinite past is that the present then becomes impossible for it requires infinite time to have gone by and that is an impossibility. Infinity can't be completed for it is, by definition, something that has no end and the end, if the past is infinite, is now, the present. So, the past can't be infinite. — TheMadFool
Insofar as "infinite" denotes unbounded (like a e.g. circumference, cycle, möbius strip) - yes, spacetime is "infinite" (or, more precisely, unbounded yet finite like the surface of a sphere or torus). '13.81 billion years' is the currently estimated 'age' only of this non-planck radius universe (which is emergent, or non-fundamental (Rovelli et al)) and not of the planck vacuum itself. :sweat:So, if time has no beginning, is the past infinite? — TheMadFool
Insofar as "infinite" denotes unbounded (like a e.g. circumference, cycle, möbius strip) - yes, spacetime is "infinite" (or, more precisely, unbounded yet finite like the surface of a sphere or torus). '13.81 billion years' is the currently estimated 'age' only of this non-planck radius universe and not of the planck vacuum itself. :sweat: — 180 Proof
I don't know. Penrose, for example, thinks so, but Carlo Rovelli doesn't seem to. A "universe" (i.e. spacetimemass manifold) might not be fundamental; if so, then "it" isn't "oscillating" and might merely be a dissipative aspect of, or fluctuation in, an encompassing environment (i.e. planck vacuum). The "paradox", it seems to me, is (mostly) apparent: "time" describes only "the universe" and not that from which "it" might have emerged (Plotinus???) :eyes:So, does this inevitable conclusion lead to the Big Bounce theory (oscillatory universe)? — TheMadFool
"Before time"? Like ... north of the north pole??? :mask:If time started with the Big Bang, did change exist before time? — 3017amen
I agree with what you said but I'm questioning the very idea of a beginning. It's nonsensical to talk of a beginning at all in a sequence (time is a sequence) in which every point has another point that precedes it. — TheMadFool
Can I not say e.g. 15 billion years ago or 100 billion years ago? Yes, I can and there's no x years ago that can be a beginning because for every x years ago point in time there's another point x - 1 years ago. — TheMadFool
Does it make sense to ask whether time had a beginning or not? Suppose for the moment that it does. So, does time have a beginning?
Suppose time did have a beginning and it was 13.8 billion years ago with the so-called Big Bang. Although some have said to ask what happened before the Big Bang? is akin to asking what is north of the north pole? it seems reasonable to consider not space-matter-energy but a time before the Big Bang. In effect it always seems reasonable to ask, for any posited beginning of time itself, for a time before that beginning. This leads to an infinite regress - for any beginning of time we can always ask for a time before that purported beginning. This then implies that to say time had a beginning is nonsensical. It (time) can't have a beginning. So, if time has no beginning, is the past infinite?
Ergo,
1. Time has no beginning i.e. the past is infinite
The problem with an infinite past is that the present then becomes impossible for it requires infinite time to have gone by and that is an impossibility. Infinity can't be completed for it is, by definition, something that has no end and the end, if the past is infinite, is now, the present. So, the past can't be infinite.
Ergo,
2. The past can't be infinite i.e. time has to have a beginning
1 & 2 is a contradiction.
What gives? — TheMadFool
The fact that we can conceptualise these ideas does not guarantee that in the universe they are possible.. — Tim3003
Hence, the principle of sufficient reason and the like are not applicable in this case. — jorndoe
Metaphysician Undercover@tim wood@Tim3003@180 Proof@jorndoe@christian2017@3017amen
Imagine, for the moment, that we have a clock that's keeping time for the universe. From our vantage point, the universe began 13.8 billion years ago; this beginning can be thought of as 12 midnight (0000 hours military time) by that clock. It is not impossible to imagine winding back this universe clock to another time like 11 PM or 6 PM before 12 midnight (when the Big Bang is supposed to have occurred). — TheMadFool
The gist of the commments in this thread is that a time before the alleged beginning (the Big Bang) is incoherent. The all-time favorite response "there is no north of the north pole" is clearly visible in the responses so far.
This however isn't a satisfactory answer. Why? Take the oldest idea about the structure of time viz. past, present, future. These 3 divisions of time are inseparable in that the future becomes the present and the present becomes the past and none of them make sense if considered to the exclusion of the other two. Since the Big Bang was, at some point in time, a present (now), there must be a time before it, the past, just as it had a future which we're currently experiencing. — TheMadFool
How are you defining "time" and "beginning" when you pose this question?Does it make sense to ask whether time had a beginning or not? — TheMadFool
How are you defining "time" and "beginning" when you pose this question? — aletheist
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