Piero Scaruffi(Copyright © 2013 Piero Scaruffi | Legal restrictions )
These are excerpts and elaborations from my book "The Nature of Consciousness"
Life On A World Line
The speed of light is finite and one of Relativity’s fundamental principles is that nothing can travel faster than light. As a consequence, an object located in a specific point at a specific time will never be able to reach space-time areas of the universe that would require traveling faster than light.
The “light cone” of a space-time point is the set of all points that can be reached by all possible light rays passing through that point. Because the speed of light is finite, that four-dimensional region has the shape of a cone (if the axis for time is perpendicular to the axes for the three spatial dimensions). The light cone represents the potential future of the point: these are all the points that can be reached in the future traveling at the speed of light or slower. By projecting the cone backwards, one gets the light cone for the past. The actual past of the point is contained in the past light cone and the actual future of the point is contained in the future light cone. What is outside the two cones is unreachable to that point. And, viceversa, no event located outside the light cone can influence the future of that point. The “event horizon” of an observer is a space-time surface that divides space-time into regions which can communicate with the observer and regions which cannot.
The “world line” is the spatiotemporal path that an object is actually traveling through space-time. That line is always contained inside the light cone.
Besides the traditional quantity of time, Relativity Theory introduces another type of time. “Proper” time is the space-time distance between two points on a world line, because that distance turns out to be the time experienced by an observer traveling along that world line.
Relativity erased the concept of an absolute Time, but in doing so it established an even stronger type of determinism. It feels like our lives are rigidly determined and our task in this universe is simply to cruise on our world line. There is no provision in Relativity for free will.
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