The Impossibility of Time Travel

A discussion from a popular forum, “The Edge of Nowhere” (http://www.edgeofnowhere.cc/ ):

Nowherelander wrote:

Any scientist who believes that time travel to the past is feasible is a delusional Sci-fi fan that can't let go.

Anon wrote:

Time travel to the past (to a certain extent) is feasible. All it would require is an anchor to the point in the past where you want to go--meaning you have to have the technology to travel to the past before you can, erhm, travel to the past. And even then, you're limited to the point(s) where you've anchored. There was a Science Channel show about this a while ago.

My reply:

The scientific assumption of IRREVERSIBILITY (Borchardt, 2004) explains why time travel is impossible. One way to view it is this:

1. It is a fact that all the planets, stars, galaxies, etc. are in motion with respect to each other.
2. That makes the night sky unique. It is never the same even two seconds in a row.
3. "Going back in time" would entail moving all those heavenly bodies back to the positions they had on the night targeted for this fanciful adventure. Good luck with that.

Reference:

Borchardt, Glenn, 2004, The ten assumptions of science: Toward a new scientific worldview: Lincoln, NE, iUniverse, 125 p.

Anon wrote:

All the laws of science run forwards just as well as they do backwards. One might say the only reason we don't see things happening backwards in time is because our memories are being concomitantly erased.

My reply:

Reversibility is the indeterministic (non-scientific) opposite of the scientific assumption of IRREVERSIBILITY. Reversibility only looks at things in isolation. When the rest of the universe in taken into account, no reaction is actually reversible, for it occurs in a context that always is changing. This is one of the reasons that we never get the exact same experimental result twice in a row. When we look at all things as being interconnected, "reversibility" is then seen as an idealization that cannot happen in reality. For many reactions we may assume reversibility because the environmental influence is insignificant, but this definitely is not possible for so-called "time travel."