h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I think slow aging travel could be more feasible than time travel. Although it is still based on a continuous line. A bit like the twin paradox where one ages a lot slower than everyone else but in a controlled manner.

If a machine existed which could “freeze” your body at that age for say 100 years and then wake you up again then we could experience a sort of one way time-travel.

If this machine was around in roman times, one could have:

Lived a few years with the Romans, then “paused” for the next thousand years, spent a bit of time with Henry VII, paused and so on…

Now this is not really time travel but in practical terms if that person was alive Today then technically for the rest of us he would have been back in time…

This is certainly feasible. As you pointed out, it's exactly the same as the twin paradox, and the only thing preventing one from actually implementing that is the lack of good rocket-propulsion technology. While I'm more optimistic about general-relativity-based travel into the future than cryogenic-based travel into the future, there's nothing physically preventing either one of them from happening.

But you could never go back in time with this right? Only forward? Like going onto a really fast space ship and coming back to the Earth in the "future."

Time Travel. A controversial and very large topic. In this case, the question
of travelling into the future with the "age travel" is discussed. The following
are my views on time travel.

I believe that to time travel, or the definition of time travel is, one has to physically move from one time period to the next without experincing time inbetween. Obviously one can have experience time faster and slower than others. Hence the phrase, "time flies when your having fun." This phrase suggests that one would experience time much faster when having fun. In the case of the "twin" problem, the twin in space would experience time at a different rate than the one on earth.
Lets look at this in a mathematical perspective. Say the average person experiences time at a rate of 1. So when they are doing nothing and experiencing time normally, as in an hour is an hour, they are at a rate of 1. If they were at a rate of 0 they would not be experiencing time at all, and therefore would be frozen. This is the case of cryogenic freezing. When someone freezes themselves and then can wake up later completely unchanged. In the case of the twins, the twin in space would be somewhere above 1, because he would be experiencing a hour in what felt like a minute. For someone to travel back in time, I believe that they would have to experience time in a negative way, as in their rate would have to be negative. This doesn't seem very possible, however, so, until proved otherwise, I believe that time travel into the past is impossible. I also believe that time travel into the future is impossible. I believe that for one to move from one point in time to another point in time without experiencing the rest, one would have to be able to travel faster than the speed of light. I don't really remember how I came up with that, I just remember realizing that thought one day. I guess I was thinking that if the slowest someone could go was 0, yet to travel back in time, they needed to go a negative speed, which was impossible, to travel into time, they would have to as fast as possible, yet speed is limited to the speed of light. I dunno.

In summary, in my beliefs, to travel back in time, someone would need to travel at a negative speed, and to travel into the future, one would have to exceed the speed of light.
Thanks.

"In the case of the twins, the twin in space would be somewhere above 1, because he would be experiencing a hour in what felt like a minute."

I think you mean his rate would be between 0 and 1... But I guess it really depends on how you look at it, after all, everything is relative.

The spacetwin travels at .75c for 2 years. Without using the full time dilation formula, we know he's aged 2 years while the rest of us aged, say, 75. So his rate compared to us is 2/75... a fraction less than one. That's how I see it.