gc
The notion of "going back in time"....how does one do that? If we entertain the idea that H.G. Wells and many others have explored...that we can squirt ourselves ...our consciousness back through time... doesn't that notion presume that we would have some sense of pre-time? If indeed the radioactive decay or other methods used for dating substances is more than (or could be more than) a window into the past...does that mean that "time" isn't actually a human construct...a concept that marks the passages of "things" from one state condition to a different state condition....
I don't think actually going back in time is possible, but that doesn't matter in my thought experiment. We can still imagine going back in time to the year "negative infinity", and then my thought experiment works. I could have said to you back in the year negative infinity that I will post this message in infinity years (which would be today). But as I mentioned before, if I said it would happen in infinity years it would never happen (ie I would never be able to post this message). Yet, here I am posting it.
I know my explanation isn't the greatest...
If "time" isn't a notional construct developed by humankind...and thus relative to the "now"...and we find some way of moving backward through it....would you expect that at some "point in time" you'd be limited by a wall of ..."non-time"? That we wouldn't be able to penetrate that barrier?
Yes, and that point is the beginning of the Universe, which would also be the beginning of time. If you want an easy way to think of how the beginning of time must have also been the beginning of the Universe, ask yourself all the different ways you could possibly measure time. Then ask yourself how you would measure time if there were no Universe.