In the ‘Butterflies’ articles and also, in the ‘Coffee Mug’ articles many things were discussed. Let’s take a quick recap:
In the first pair of articles (Butterflies… — Parts I & II) the Aristotelian [absolute Time, absolute Space] and the Galilean [absolute Time, relative Space] ideas on the structure of spacetime were briefly discussed.
The second pair of articles (Coffee Mug… — Parts I & II) focussed on the tenet of realism. These articles briefly provided the distinction between its ‘spooky’ version and ‘local’ version. Local Realism can be understood as the combo of two beliefs: The existence of objects from their own side independent of consciousness; AND, The impossibility of a past ‘cause’ (at one location) resulting in a future ‘effect’ (at some other location) faster than the propagation of light between the two locations.
At the end of the last article, it was mentioned that, this ‘upper limit’ given by the speed of light leads to a fundamental change in our view about reality and the spacetime structure — as provided by Einstein’s Special Theory of Relativity (STR) — not only by maintaining the relativity (i.e. non absoluteness) of space, but also by abandoning the (Galilean-Newtonian) notions of ‘absolute time’ & ‘simultaneity’, by pointing out the equivalence of mass and energy etc…
[Details of the physical ideas of STR cannot be properly discussed without involving some technicalities. We will get into STR and its generalization including gravity, i.e. GTR (Einstein’s General Theory of Relativity) in some future articles.]
ALRIGHT — Butterflies have done with flying and we all have done with drinking coffee from our favorite mugs!
What next? — Let’s consider another very important tenet on which physics frameworks are based: It is the tenet of ‘determinism’ — the belief that every present or future event, can be fully accounted for, as the effect of past causes.
A very simple example of determinism can be given as follows: You are driving car at a speed of 60 kilometer per hour. Suppose you accelerate the car for 10 seconds at the steady rate of increase in speed by 2 kilometer per hour in a second, then — what will be the speed of your car at the end of 10 seconds? This question can be easily answered.
So — your car’s present state of motion [i.e. moving at a higher speed than 60 km/hr] can be understood as the effect of past causes [mechanical forces leading to its acceleration] that resulted in the change of its past (initial) state of motion [i.e. moving at the speed of 60 km/hr].
A simple mathematical relation between initial and final speeds readily ‘determines’ the value of the increased speed of the car (i.e. 80 km/hr).
Another example strengthening our belief in the tenet of determinism can be provided by a sequence of events — a situation that we often come across in comedy movies: In a restaurant someone collides with a waiter, who is carrying food-plates or glasses of water — causing those things to fall down on the floor and break into pieces…
(In fact the chain of such events is generally shown longer in the movies than this — causing some more funny events!) — The ‘broken state’ of those plates or glasses can be seen as the ‘effect’ of past ‘causes’ involving (but not limited to) the collision of the waiter with someone — their trajectories crossed each other!
Some of the past causes leading to an effect in the present and that effect is in turn playing the role of one of the causes for some of the effects in the future — believing in such a connectedness (‘chains’) of events is what the tenet of determinism is all about.
It can be said that the trio of tenets — Realism, Locality and Determinism: all taken together — leads to the ‘classical physics’ notion of CAUSALITY.
Causality is an almost 24-century old notion in science!
Throughout the historical development of more & more correct and general physics frameworks — from the ancient Greek (Aristotelian) era to the 20th century modern physics ideas — the notion of ‘causality’ is seen to be essentially maintained.
Though maintained, its meaning and interpretation has, however, undergone several modifications. In the realm of quantum phenomena the notion of causality is a topic of lively debate.
Maybe it’s a good idea to begin with the “Aristotelian Causality”…
Exploration continues…
LinkedIn: https://www.linkedin.com/in/dr-vikram-athalye/recent-activity/articles
