# Does a light cone only effect the time an object has lived?

I'm confused about light cones and I've driven a crazy scenario to try to represent it.

Let's say I can move through my past light cone to the exact time of my birth. If I kept on moving back could I move to a time before I was born? Therefore my question is, when they show light cones in space-time diagrams do they apply to our own past our the past of the time throughout the universe. Does this mean that in the -t direction, time for us only goes as far back as our birth. Sorry if this sounds too confusing.

Past and future light-cones really only apply to a single event (location in space and time, call it $P$): the future light cone is the set of all events that can be causally affected by $P$; the past light cone is the set of all events that could have causally affected $P$. If you examine the event of your birth (call it $B$), it will have its own past and future light cones (the future light cone of $B$ overlaps with the past light cone of $P$, and all of $P$'s future light cone is contained in the future light cone of $B$).