Time travel

Time as a dimension

To Earth, time has no meaning. It is just future, now and past: another dimension  like up, here and down; forwards, here and backwards; and side, here, other side. The dimensions familiar to us are interchangeble: tilting forwards, here and backwards a quarter circle gives up, here and down: turn it a quarter circle and it becomes side, here and other side. To Earth, time is the same and changing time is no different from changing location. There are rules:

Beings can see, hear and interact with all other objects withing their life spans.

All  life has a span: It is born - or germinates - matures, grows old, and dies. That its life span. Earth has Its own span which began with the first living organism in the primordial soup and will end when all life becomes extinct. Sol's span is that of the solar system. 

The basic rule is to do with life spans: everybody can see and interact with anything or anybody within their own lifespan. Simple, that's what we are all familiar with. There are exceptions, however:

Power perceives power.

Those adepts with the aptitude and training to commune with Earth or collect Sol's power, can see, hear and interact with objects and people that exist within Earth or Sol's spans;  so communing with Earth or collecting Sol means, for all practical purposes, that  they can see, hear and act on anything and anyone at any time. It is power that perceives power. The unfortunate object of an adept's attention cannot see, hear or react unless touching that adept. 

So, when out of their natural lifespan, a time traveller is invisible and intangeable to the population except those who have Earth or Solpower.

There are those who have the ability to commune with Earth and collect Sol, but who have not been trained, so their talents are dormant. They can generally sense power and have an impression of auras, but without training, cannot use them.

Sol and time travel

Sol's power is just power, like heat or light; it has no dominion, no will, it is solely a resource, like air and water. Time travel is a non sequitur and can be disregarded.