Please forgive me if this is stupid/common sense/been asked a million times before, I'm an amateur. I've recently seen an explanation for why time travel wouldn't be possible which is roughly this: If you travelled from Point A to Point B at the speed of light for 1 year from the perspective of people remaining at point A then no time would have elapsed as per the traveller's perspective. If on arrival you look at Point A then you would see it as the same as when you left. Then by travelling back for 1 year then you simply would have caught up with those at Point A (Presumably because light coming towards you along with the traveller's speed of return would balance out.
My question is this: What if you introduced a Point C along the shortest length of an isosceles triangle. The base of which being Point A - Point C (shortest length) and Point A - B and Point B - C being the longer lengths.
If from the perspective of the person at Point A you travelled at light speed for 1 year, then without looking back travelled for 1 year to Point C, then 2 years would have elapsed but no time for the traveller. If you looked from Point C to Point A which is shorter than 1 year, do you look back on the past?!
