ARROW OF TIME
Presence of motion is the most obvious way time is perceived. Normally we do not think of forces as part of time. Once we
incorporate forces into our definition of time the solution to arrow of time becomes feasible. The direction of arrow effect is
mainly due to presence of forces and the feeling that time flows so called bug on the windshield effect.
Pure motion can be bidirectional. However forces create work against a gradient. Objects fall in gravity. Heat is applied to boil a
kettle, liquids mix, heat dissipates, and batteries lose charge.
The symmetry of time (T-symmetry) can be understood by a simple analogy: if time were perfectly symmetric then it would be
possible to watch a movie taken of real events and everything that happens in the movie would seem realistic whether it was
played forwards or backwards.
For example, a movie showing a cup falling off a table seems realistic when run forwards, but seems unrealistic if run backwards.
On the other hand, a movie of the planets orbiting the sun would look equally realistic run forwards or backwards; either way the
orbital motions would appear to conform to physical laws.
Events requiring a force to produce an action has a strong sense of direction.
Suppose I pick up a rock and throw it and see it fall. Now why I do not ever see a rock suddenly bounce off the ground fly up in
the air and land in my hand which is waiting open to suddenly grasp it. That does not happen as there is no force gradient in the
reverse direction. The movie of planet orbiting the sun looks realistic if run forward or backward as there is no force gradient
involved in the different frames of the movie in either direction.
A hammer smashing a cup of tea to pieces is a cause. While cup of tea spontaneously assembling into a cup and pushing up the
hammer is not cause and effect. This sequence we have learnt by experience that forces produce effects and effects do not
usually produce a force. For cup pieces to assemble into a cup is to expect forces to work against a gradient and motion to
reverse without a cause.
Our perception of passage of time makes us see the arrow of time. Once we know that there is no passage of time then the
problem of arrow of time is half solved. The other half is the wrong expectation that things may happen without cause. Also the
question why we do not remember the future but remember the past becomes redundant when we know that there is no such
thing as passage of time. There is only present and the memory of the observed present we call past.
In summary the arrow of time is due to presence of forces. Motion as well as forces are part of time. The action of forces across
gradients sets the direction of events. We recognize the direction because of experience.
incorporate forces into our definition of time the solution to arrow of time becomes feasible. The direction of arrow effect is
mainly due to presence of forces and the feeling that time flows so called bug on the windshield effect.
Pure motion can be bidirectional. However forces create work against a gradient. Objects fall in gravity. Heat is applied to boil a
kettle, liquids mix, heat dissipates, and batteries lose charge.
The symmetry of time (T-symmetry) can be understood by a simple analogy: if time were perfectly symmetric then it would be
possible to watch a movie taken of real events and everything that happens in the movie would seem realistic whether it was
played forwards or backwards.
For example, a movie showing a cup falling off a table seems realistic when run forwards, but seems unrealistic if run backwards.
On the other hand, a movie of the planets orbiting the sun would look equally realistic run forwards or backwards; either way the
orbital motions would appear to conform to physical laws.
Events requiring a force to produce an action has a strong sense of direction.
Suppose I pick up a rock and throw it and see it fall. Now why I do not ever see a rock suddenly bounce off the ground fly up in
the air and land in my hand which is waiting open to suddenly grasp it. That does not happen as there is no force gradient in the
reverse direction. The movie of planet orbiting the sun looks realistic if run forward or backward as there is no force gradient
involved in the different frames of the movie in either direction.
A hammer smashing a cup of tea to pieces is a cause. While cup of tea spontaneously assembling into a cup and pushing up the
hammer is not cause and effect. This sequence we have learnt by experience that forces produce effects and effects do not
usually produce a force. For cup pieces to assemble into a cup is to expect forces to work against a gradient and motion to
reverse without a cause.
Our perception of passage of time makes us see the arrow of time. Once we know that there is no passage of time then the
problem of arrow of time is half solved. The other half is the wrong expectation that things may happen without cause. Also the
question why we do not remember the future but remember the past becomes redundant when we know that there is no such
thing as passage of time. There is only present and the memory of the observed present we call past.
In summary the arrow of time is due to presence of forces. Motion as well as forces are part of time. The action of forces across
gradients sets the direction of events. We recognize the direction because of experience.
