Time travel

Richard looks at the potential for time travel

He takes a pretty deterministic approach

A time traveler may play a role in making the past what it is. But she couldn't make it what it isn't...
I'm not sure that it really does make much sense to speak of a second temporal dimension, or 'personal time'. More plausibly, the static historical dimension is the only temporal dimension that there is.

Preparing the groundwork - this seems to suggest that the arrival in the past fundamentally precedes the arrival in the future.

> Further, event B causes event A (two time travel events). If B hadn't occurred, then neither would have A.

Here he effectively denies that you could kill yourself in the past because if you did you would prevent B.

> Though note that one way out of this... [multiple universes]

He then misses the answer right in front of him.
multiple universes time travel is not really time travel it just means thee must be many worlds with a single "time" just with similar events happening more or less quickly. I think this creates major problems for you actually finding these theoretical worlds where you could jump into the past because they are out of alignment with your own world. (I can explain that in a later post)

I think the argument here tends towards a different solution – this is the "time traveler is part of the system" way of looking at time travel.

In this way of looking at it you would go back in time do everything you could to kill Hitler but when you returned find absolutely nothing changed. You would fail or maybe discover Hitler was killed but it was kept secret or something along those lines because at t2 your actions had already influenced t2.

You can say “that doesn’t make sense! I could just decide to change the plan” but you have been arguing there is no external timeline and the t1 is already factored in at your t2.As a result in this model the (theoretically potentially) infinite loop feeding in at t1 through to t2 and back to t1 are all part of the history at t2 - so it would turn out as above.

You could build this out of a paradox by either saying

1) you create an initial unstable state (lets say you go back in time and kill yourself) but in the next “oscillation” that would happen a bit differently because you are not there to kill yourself. It bounces back and forth until a solution arises that doesn’t create a change and then in essence that example is reinforced an “infinite” number of times and the odds of you experiencing a paradox state tend towards zero.

2) Nature automatically resolves the paradox even if it requires twisting of other laws of physics (which could well be defined largely the same paradox avoiding principle) because the paradox creates a sort of supreme low energy state - rather like how exposing a vacuum results in air rushing in. I see quantum mechanics as a useful tool for solving that.