Light cone
“In general relativity, the future light cone is the boundary of the causal future of a point and the past light cone is the boundary of its causal past.” [Wikipedia]

Nothing can travel at the speed of light, therefore nothing can travel faster than light[1], therefore your impact on the universe at large can be measured as a sphere with radius ‘c‘ multiplied by your age, viz: the distance that light has travelled since you were born.

This website computes that distance, and tells you what stars are within that radius, updating week by week…

Cute.

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[1] … unless it started out that way.