end of story
The universe is expanding, distances are getting bigger, and there is no reason to think that it'll suddenly decide to stop and get small again.
Balloon theory was blown up by the discovery of an increasing cosmological constant (aka dark energy).
Once a fire has burned to ash, you can't turn it back into wood again. Cyclical time is wishful thinking, contradicted by all evidence.
> The universe is by definition a closed system.
There is no de-finit-ion, that's my hole point (excuse the pun, it fits better than any other time)
> The universe is all that exists, if there is something that could have an effect on it, it would be part of the universe.
Yes sure, but what if it's endless? That's not closed in the sense of thermodynamics I don't think.
To conclude from your statement, that the universe is a closed system, kind of requires to presume universal entropy increase, in case of infinity. I can't do the maths though, so I might be wrong. It's just a hunch.
> The universe is expanding, distances are getting bigger,
The visible ...
background radiation may invite inference, but really you get interference.
> and there is no reason to think that it'll suddenly decide to stop and get small again.
In a e.g. 10^50 years would not exactly be suddenly
> Once a fire has burned to ash, you can't turn it back into wood again. Cyclical time is wishful thinking, contradicted by all evidence.
I don't disagree.
It's easy to take these mythological concepts and restate them in a way that seems to imply hidden scientific knowledge or awareness - Christians have done that with the Bible often enough:I know some who quite literally believe the locusts mentioned in the book of Revelations are Apache helicopters, for instance.
But any resemblance between the flights of fantasy in religion and scientific truth are at best coincidental when the science was arrived at through experimentation which depended on generations of knowledge about the physical world the ancients didn't have. Simply sounding kind of correct in hindsight doesn't count for anything.