On Sat, 14 Jul 2018 08:18:54 +0200, Paul Schlyter
wrote:

On Fri, 13 Jul 2018 22:39:34 -0700 (PDT), RichA
wrote:
How about, "functionally impossible?" Apparently, you can if you
try enough, run through a brick wall. IT might take 115 trillion
years, but you might make it, according to quantum physics.

If you have 115 trillion years at your disposal, all you have to do
is wait. Within a few centuries, perhaps a millennium, the brick wall
will have fallen down and you can just walk through its remains. And
then you'll have 114999999999000 years remaining of your 115 trillion
years...

The evidence suggests that the time available for conscious life is
finite. And finite is all you need to end up with a universe where
time travel is never invented, despite being possible.