I have written in the past about consciousness being an accumulation of sensory experiences [see ‘Is there are real ‘you’ or ‘I’? on March 6th, 2019]. Our memory consists of fragments of images, sounds, smells and feelings from the past that we can re-assemble into a complete experience often triggered by something in the present that resembles a fragment of a past experience. We can time travel in our minds by thinking about the past. It is so ubiquitous that we barely stop to think about it. Yet, we are fascinated by the possibility of time travel into the future. However, our subconscious minds are constantly time traveling into the future [see ‘Predicting the future through holistic awareness’ on January 6th, 2021]. They are constantly making predictions about what will happen next, whether anticipating the path taken by a ball so that your hand can be positioned to catch it or picking up an umbrella as you leave the house so that you do not get soaked when it rains later in the day. The further we attempt travel into the future the less dependable our predictions become and I suspect the same is true for travel backwards in time. The reliability of our recollection of past experiences become less as time and entropy erode the connections between the fragments in our mind so that we struggle to reassemble all of the fragments in the correct order and our personal history is unintentional rewritten.
As you may have gathered from last week’s post [Man, the Rubbish-Maker on October 26th, 2016], I have been reading Italo Calvino’s Complete Cosmicomics. In one story, ‘World Memory’ the director of a project to document the entire world memory in the ‘expectation of the imminent disappearance of life on Earth’ is explaining to his successor that ‘we have all been aware for some time that the Sun is halfway through its lifespan: however well things went, in four or five billion years everything would be over’. The latter is one of the scientific conclusions around which Calvino weaves these short stories and this one put into perspective the concerns expressed by some of my students on both my undergraduate course and MOOC in thermodynamics the prospect of a cosmic heat death resulting from the inevitable consequences of the second law of thermodynamics [see my post ‘Cosmic Heat Death‘ on February 18th, 2015]. The second law requires ‘entropy of the universe to increase in all spontaneous processes’. Entropy was defined by Rudolf Clausius about 160 years ago as the heat dissipated in a process divided by the temperature of the process. The dissipated heat flows into random motion of molecules from which it is never recovered. So, as William Thomson observed, this must eventually create a universe of uniform temperature – an equilibrium state corresponding to maximum entropy where nothing happens and life cannot exist. Entropy has been increasing since the Big Bang about 13.5 billion years ago. And as Calvino writes, the sun is about halfway through its life – it is expected to collapse into a white dwarf in 4 to 5 billion years when its supply of hydrogen runs out. These are enormous timescales: the first human cultures appeared about 70,000 years ago [see my post ‘And then we discovered thermodynamics‘ on February 3rd, 2016] and history would suggest that our civilization will disappear long before the sun expires or cosmic heat death occurs. A more immediate existential threat is that our local production of entropy on Earth destroys the delicate balance of conditions that allows us to thrive on Earth. See my post on Free Riders on April 6th, 2016 for thoughts on avoiding this threat.