I attended a talk by Oliver Pooley on time and our understanding of it in light of relativity and quantum mechanics. I will try to outline some of the themes although the quantum mechanics part is probably beyond my grasp.

As usual, there is terminology problems as several different views are contained in two terms.

Presentism: the view that the present is real. Some presentists hold that the past is also real. The present is metaphysically special and shared with all observers and is objective. This is the common sense view of time.

Eternalism: the view that the past, present and future are equally real. The present time is a subjective part of the greater whole of what is real.

When we start introducing modern ideas of science into our understanding of time, we begin to find some things that seem counter intuitive. For example, the speed of light is finite. If we see a light bulb being turned on in our house, we might say “I just say the bulb being switched on” - although this is only an approximation to the truth. We are used to what we see as being the state of the world at the present time - rather like Berkeley’s view of perception giving things reality. Of course, since we are separated by some distance, we each perceive objects at different times and the present time becomes subjective.

What about stars? Since light from the closest star (apart from the sun) takes 4.37 years to travel to the Earth, what we see certainly is not in the present time. It is necessary to add this time delay to our statements. If the star exploded, when we saw it we might say “that star exploded 4.37 years ago”.

Things start getting confusing when we have observers with different relative velocities. Imagine we have a train passing through a station. At the moment the train in the middle of the station, a light at the mid-point of the train is turned on. This light travels away from the source like an expanding sphere. An observer on the train sees it arrive at the end of the train at same moment as it arrives at the start - this is as we might expect.

relativity.png

What is unexpected is an observer on the platform sees the light travel from the middle of the train towards the first and last carriage. BUT the end of the train is moving toward the observer AND the front of the train is moving away. This makes the light appear to reach the end of the train before it reaches the front!

The conclusion is that simultaneity is only relative to each observer, if they are moving with different speeds. It is unsurprising that this theory is called (special) relativity! Since we cannot agree what events are simultaneous, we cannot then say there is an objective “now”.

The general theory is too lengthy to go into here but it also hints at Eternalism. Quantum Mechanics is too mind boggling to attempt to describe. I regard QM as a work in progress. QM suggests many different possibilities ranging from Presentism to the reality of Past/Present and All Possible Futures! Since QM and relativity are incompatible, work is actively being done on this subject.

As they said in the computer game Half-Life 2:

I trust it will all make sense in the course of.. well.. I am really not at liberty to say.

Anti Citizen One