CauTi0N wrote:

I apologize, I was rushed off the computer during my last post.

My reasoning for saying time travel is limited to the time constraint is because it would require an infinite loop.

If I were to travel back in time to talk to my 6 year old self, then that means when I was 6 years old I should have this memory. However, when I grow up, I'll do it again. And again. Point A, when I'm 6 years old, to point B, when I'm say 50 years old. Then, from point B, to point A, infinitely. The chain cannot be broken because if I don't do the jump from point B to point A, then point B can never occur, and therefore at 6 years old, I can never re-meet myself. So, if the chain can't be broken, it must be that it continues forever. If this is true, than that would be the only cycle that carries on forever, and therefore that would be really the only time interval in existence.

No. Just no. That doesn't make any sense what-so-ever. If I'm understanding what you're saying, it's analogous to claiming that the existence of circles precludes any space existing that isn't in the range of the circle.

The issue I have with time travel is basically 2 things:
1) If it were possible, it should have affected us by now. I would think, if time travel were true, people would be most interested in the actions of the beginning of time, and in the most historic moments - Alexander, Napoleon, Jesus' time, Socrates, etc. It's highly likely that anyone would want to, at the very least witness this, and if time travel were true, then this would have already happened.

The type of 'time travel' I am discussing here does not necessarily allow this - I am arguing that it is conceivable that the universe-in-the-future causes itself in the past (not that that's what happened, just that it's conceivable). That doesn't necessarily mean it's possible for creatures in the future to come back to the past.

Secondly, there are a number of solutions to that argument that don't involve time travel in the sense of people moving through time being impossible. For example, it's entirely possible that we wipe ourselves out before inventing time travel. Or that it requires so much energy that it's out of our reach (considering the (known) solutions to the Einstein Equations with closed-timelike-curves (i.e., time travel), this is a real possibility), or the 'time machine' can't be taken back to before it was constructed (also quite viable - the Roman ring construction, for example, won't allow you to go back in time to before the construction of the ring).

Secondly, if time is a manipulative dimension like time travel postulates with, then I have a lot of questions on how the energy works to do so: If I travel back to the 16th century, then there is less energy somewhere else to make up for my matter being there in the 16th century. And, if there has to be an infinite loop, then this change would continuously happen, and there would be some kind of missing energy that nobody is able to account for. It just seems far too convoluted and... ridiculous to be possible.

You're thinking about time in terms of some kind of meta-time, where you can stand back and watch the timeline moving. It doesn't work like that. It doesn't 'keep happening', there's just some matter/energy moving from the future into the past, which is really as innocent as some matter/energy moving three metres to the left. There are some questions regarding the nature of causality in a time-travel-allowed universe, yes, but nothing irresolvable - for example, it's possible that interactions that cause paradoxical causality (the Grandfather paradox, for example), are literally impossible, in the same way 'spatial paradoxes' aren't possible.

Regarding dark energy: "[dark energy] is not known to interact through any of the fundamental forces other than gravity."

That doesn't imply that its contribution to the universe's expansion is gravitational, as such. Dark energy (probably) doesn't act like a gravitational repulsor, producing antigravity - it's just a sort of negative pressure on the universe. And may well change over time.

An infinite universe would not require an initial cause. Anything infinite implies always existing (though this gets tricky with defining logic, which isn't necessarily infinite but is always existing - our math discussion you talked about), and so you don't need to explain a First Cause in that sense because there can't be one. It always was. That's why, if there is a First Cause, some call a "Creator", then that "Creator" is always existing, so nothing caused it.

I still don't accept the premise. You haven't given me any reason to believe that 'infinite' things require no cause. You haven't even defined 'infinite' in any way. What, precisely, do you mean here? What if the universe is infinite in time? Does that count? You've claimed an infinite regress of universes does need a cause, but surely that's 'infinite' in another sense?

The reason why the "Creator" acknowledgment is given is because the majority of the cosmological argument is empirical and deduction - stop every other portion, all you are left with is this final answer, which can't be disproven (because we know nothing about this "Creator"), though on surface is arguably weak.

My point is more that you don't know it's a Creator, as such. Even if the argument holds, all you know is that there was a cause that was not itself caused. You can start to reason about its properties on the basis of what things can be uncaused, but your current claim that 'infinite things can be uncaused' basically allows open slather. The vast majority of the possibility space you've carved out here are not recognisably a 'Creator' so much as a cause - you wouldn't say that gravitational attraction is the Creator of the Earth, but it certainly created it.

It's similar to Descartes' methodology to prove logic as the only true way to attain knowledge - because there are problems with empiricism, authority, and intuition, but logic has/can never fail(ed), it is the only one that can provide "true knowledge," even though it's more limited.

I don't see the similarity, myself.

And more to the point, Descartes was wrong. Logic works from premises, premises have to come from somewhere - ultimately you're left with either axioms (i.e., believe this for some reason and then we'll see where we get), or circular logic, or infinite regress. You can still prove things, but they're all hypothetical in nature (i.e., "Assume a universe like this. If that is the case, then this."). It can't absolutely prove anything about /the/ universe (or even that there /is/ one), just things about /a/ universe.

My position is that given that fundamentally all means of 'knowing' the universe ultimately have to be based on axioms, you may as well pick the axioms that give you the most workable universe - you'll never know either way, and it's a lot easier this way. So you may as well consider it axiomatic that there /is/ a real universe, that it behaves in consistent, measurable ways, that kind of thing - and if those are your axioms, empiricism becomes a fantastic tool for understanding reality. Sure, it inherently stands on assumption, but so does everything else, and these aren't exactly bad assumptions.

My understanding is there is not enough information of dark energy to support either way, but given what we know now, the Big Collapse is not the supported/leading hypothesis.

Big Crunch is the more commonly accepted term.

And yes, it's absolutely true that there isn't enough evidence to come to the conclusion "cyclic universe" as of yet. I'm not saying that's what happened. I'm just presenting it as a possibility - an alternative to "There was an uncaused cause" to demonstrate that something in the premises or logic is screwy and the argument doesn't work (because it isn't /necessarily/ true), not claiming that's what actually happened.

I'm not sure what the favoured fate-of-the-universe model is in cosmological circles, but I suspect it's perfectly balanced expansion/contraction and heat death (i.e., flat universe).

CauTi0N wrote:

Time travel depends on the idea that fate definitely does exist, and that the only time interval to ever exist is the infinitely repeating one that is occurring between point A and point B on the time spectrum. If this were true, then what's the point of that? It's more illogical than anything else ever proposed... ever. I'd believe unicorns exist before I believe time travel exists.

...What? That doesn't even make any sense. I honestly have no idea what you're getting at here. There's no requirement for a mystical concept of 'fate' for time travel. I don't see why determinism is even strictly necessary (although I am a determinist). I don't see why it restricts time as a whole dimension to two particular points, either. The fact remains that solutions with particles travelling back in time are valid solutions to Einstein's Equations. There are even trivial setups with time travel in them - for example, if the entire universe is rotating, then every particle's future eventually reaches its past (that is, they 'rotate' through time, as well, as a consequence of how space is warped). You can do math on this stuff.

I'm not sure my "dark energy confusion" is really much of a confusion. It's a scientific fact that the universe is expanding at a quicker rate than it did at the beginning of the Big Bang. If this could reverse at some point, then it's possible for a Big Crunch, but it's unlikely even mathematically - energy will try to reach it's maximum potential, and if that is infinity then it will never reach it - therefore it's impossible for a crunch to occur.

You are not understanding dark energy (that much is clear because you're tying it to gravity, and it's not much like 'antigravity' at all). And versions of it that can reverse 'sign' do exist in models. Cyclic universes very much remain on the cosmological cards.

Also, keep in mind that science remains empirical entirely. A Big Crunch is entirely far'fetch'd to the point where it's a mere hypothesis, and a weak one at that, because there is no evidence to properly suppose that everything can return to it's original spot. As well, it relies that dark energy could change it's pressure from negative to a positive gravitational force, and since that hasn't happened before either, there is absolutely no evidence to support the notion that it can magically change into the opposite of what it originally is.

Everything doesn't have to return to its original spot. For starters, a big crunch implies that at some point there won't /be/ any other spot for things to be in, and more to the point the universe is not constrained to turn out the same every time. Same physics, probably (depending on model), but a different starting condition. Crunch-bang works.

And yes, it's certainly a hypothesis. Not really a 'weak' one, in the sense that it's unlikely - it's not really any less likely than many of the other fate-of-the-universe models - it is quite hard to test, which could be a problem, but that's okay. I'm not saying it's definitively what happened. I'm just giving you some possible causes for the universe - in this case, 'the last universe'.

As well, infinite regression and simply ignoring the initial "first cause" of an infinite amount of "finite causes" turns the debate away from philosophy - it's hiding under a rock essentially, saying "I don't want to know the answer so I'll just ignore it." It's better to investigate and still not know than to simply guess that there is no answer and ignore it (when it deals with an important issue, such as the existence of the universe and, in turn, us).

You misunderstand. I'm not 'ignoring' or 'hiding' or anything like that the issue. I'm saying that there doesn't necessarily have to be a magical 'first cause' holding up the entire pile. Infinite regress, in this sense, is basically saying that the universe 'always existed' (Although maybe it was banging and crunching during that time). There was never a point in time where it didn't exist. It's a model. In fact, back in the 1930s, it was the dominant cosmological theory. I don't see a good reason to rule out that possibility, and I don't see it requiring a 'first cause'. Basically, I don't see why things can't just 'have always existed' for no particular reason.

The matter of finitude or infinitude is a huge matter - one that can't simply be brushed off like you imply it can. It's important if something is finite, you know something caused it. 1 + 4 = 5 is a debatable "cause" of the number 5, so it's a bit of a weak argument to say that 5 doesn't have a cause, even

Finitude/infinitude doesn't imply causedness/uncausedness. That's the point. I see no reason to believe they're correlated at all. Consider - if the universe is provably infinite in space, does that mean that it doesn't need a first cause? Why? What's so different?

Maths isn't a great example here, because you're onto the tricky ground of the "Maths: Discovered/Invented?" argument. And more to the point, because maths is logic (in the sense that the laws of logic are an offshoot of maths), and one wouldn't talk about the 'cause of logic'. The 'rules' are a different class of thing - they're inherently uncaused (similarly, you don't ask "what caused the law of relativity?" because the question doesn't make sense.)

To be continued... when CauTiON posts more!