huckelberry wrote:"Elapsed proper-time is a private issue.
It depends on the spacetime-path taken.
Different spacetime-paths have different spacetime-lengths."
Tobin, i am sorry I could not find anything in your link that I understand as different than what I have described previously with my space traveling buddy.Perhaps my buddy has narrowed my vision. I am sure that I am not the one who knows all things for this subject. I am not going to try to obligate you to agree with my reading.
"The characteristic feature of Galileo's Spacetime was the set of horizontal slices representing "planes of simultaneity". On a given plane, all of its events are simultaneous. This is the notion of Absolute Time, in which all observers agree on the elapsed-time between two given events. In the particular case of "zero elapsed-time", all observers agree that the events on a given horizontal plane are simultaneous."
Instead - The Einstein-Minkowski Spacetime ends the concept of absolute time
"Einstein immediately realized that a consequence of his postulate was that the our understanding of the nature of time needed to be revised. The set of events that are simultaneous to one observer are not simultaneous to another observer!"
The sequnce (or order) is not absolute and the way an observer may slice up space time might be different from observer to observer.
"In Einstein-Minkowski spacetime, each observer will slice up spacetime in his own way. There is no universal way to slice it up. "
What this means is observers can see sequences in any order. One observer may see the what we would call the past, another might observe the future depending on the distance, speed, direction, and gravity. The ramifications of Einstein-Minkowski Spacetime means what we perceive as the past and future is not true for all observers.
Your statement that a space traveller could not view what we perceive as the future is absolutely false under this model. One simple way a space traveller can do so is if he is moving at close to the speed of light for example. He would see the future unfold before his eyes. Another simple example would be a space traveller far from Earth, say 1 million light years away, would view the Earth not as it is now, but as it was 1 million years ago in the past. These are just two simple (but direct ways) that observers can see the past (or the future).
"You lack vision, but I see a place where people get on and off the freeway. On and off, off and on all day, all night.... Tire salons, automobile dealerships and wonderful, wonderful billboards reaching as far as the eye can see. My God, it'll be beautiful." -- Judge Doom