Nature has revealed a beautiful secret! The behavior of the Universe becomes very simple if it is described in a way in which space and time are symmetric. What makes it seem hard, is the fact the we must live our lives by standing at a point in space and watching time pass, but not the reverse. It’s like our perspective in riding the Earth around the Sun, which seems as if the Sun were going around us. However, the heliocentric equations are much simpler.

“Time is what keeps everything from happening at once.” - Attributed to John Archibald Wheeler Quoted by Woody Allen “Time flies like an arrow; fruit flies like a banana.” - Groucho Marx ‘Backward turn, turn backward, O time in your flight. Make me a child again, just for tonight.’ - Elizabeth Akers Allen

Nature chooses the space-time path of minimum action and that path must contain an integer number action “quanta” Action canonically welds: Momentum-to-Length Energy-to-Time This leads to an “Uncertainty Principle” between them

LEAST ACTION – What is the path between (x1,y1,t1) and (x2,y2,t2) ? Total Energy = Kinetic Energy + Potential Energy “Action” = [Kinetic Energy – Potential Energy] t The particle does whatever it wants, but we see the path where the Total “Action” summed over all points adds up to the smallest value. On this path the Total Energy is the SAME for each point