Not posing an argument , just presenting you with piece of relevant insight .
Suppose, hypothetically, there was no inter-star interaction to here, or some other planet with peacefully evolving species , what they'd experience would always be , single time-line . That's not the case here, never has been .
Definition and physical properties of time and space are percieved differently by inhabitants of different solar systems across the Universe .
Why , simply because it's the particular Star system(s) interactive forces dictating the initial rule. Start with Star mass and spin of rotation, its magnitude and age , the speed photons are emmitted from its surface , the gravity imposed on all its satellites , then similarly, nature of its satellite planets that is going to imply the way of sustainance of biosphere and in particular, long living intelligent organisms ( beings ) inhabiting the biosphere, living long enough to evolve space technologies, establish contact with other civilisations in space and finally , visit some other place , in other galaxy , solar system, having its own time-line.
For the first place, the speed of light is constant with variables, as well as nature of time and space is biological constant with variables responsible for daily and life long biorythms of each of the organisms naturally inhabiting its biosphere and interacting actively with intelligence of its inhabitants ,
forcing them to assume certain form, allowing certain level of intelligently organised biological matter.
Their time-horizon , they're able to perceive naturally as 'reality' is specific to them too, as individuals and a specie . What we on earth percieve as immediate, present and predictable reality , is relative to physical circumstances of our habitate in another words.
For inhabitant of another galaxy-star system etc., depending on what kind of complexity structure of bio-intelligence is allowed on such a place , time perception and time-horizon of clearly percievable events therefor may differ in several degrees .
Translated to human terms, ''immediate presence'' may last much longer than here, for example .
Now, the time-space , time-line chaos comes to action when civilisation A comes to visit civilisation B in distant part of Universe. Originally, they both had their single time-lines with natural variables .
But the all changing moment occurs when they meet together and one of them, bring their time-line along. The law of spacy logic sais it will be the more advanced of them who finds and succesfully visits the other .
What happens next ..ideally, hand shake and exchange of information .. ( generally .. exchange of information is what is destined to happen between biological entities on any level )
but what's been substantially affected is the B civilisations linear time-line as a new one, equally powerful if not more , depending on nature of the meeting , was introduced . Biological clock of B civilisation received additional program.
It's not able to organise itself according to it , not immediately, till its time-space habitate remains stable and dictates most of the biological rules .
Yet, as intelligent system programmed with new time horizon, it's ocassionally able to use this 'alien' software and affect its own original -time-line'.
The time-space code donned won't be forgotten but will stay with the specie even after A civilisation leaves and will expand the particlar beings time-space perception.
Civilisation C happens to visit B shortly after, it too donnes different time-horizon of events. D, E, F..do the same .
It takes time to B to be able to use time-travel software succesfully , technically taken, as we know that its mind travel equipment has been expanded previously so in turn, it's not only on the way to evolve its own controlled technologies that extend over the edge of its limited space-time but may be also donned ( or recover , accidentally..) such technologies from F civilisation that crashed.
Need to note , that F civilisations time-chair was not designed for humans ( B ) previously and so..what B experiences attempting to drive neigbours Jaguar is Fs time-horizon ( distorted by B slow adaptability ratio to Fs technology ).
However, the result won't be 'just a variable' , but it will be civilisation Fs perspective, prospective time-line in a head and hands of ( 5 year old ) B.
B finds out that Fs device has multiple variables as it is able to simulate other few civilisations time-horizons. B can't decide which is the most correct so hopefully decides for the one with least calamities at the end.
But, is B actually able to alter its own time-line ? Yes, it is, by bringing information in to its own B time-line and letting it evolve as such .
Of course, it's still a way far from being 'its own' , as the particular piece of information belonged to F and F left . It'd be only be true for F if F stayed here .
B just can't follow F in everyday life, and the information it has retrived is not exact , maybe not be accurate in the sense of event ,
but its meaning is similar to coded information, such as computer program you buy and it works for you .
If F ever comes back..meets B and the information is decoded and presumption dissolves .
So yes, time-lines had been affected . It will take time
to decide whether it was A, C, D, F... ( apologies to the rest of them not quoted ) who have mankinds best interest in their heart...
