Laplace’s Demon
Demon? From the Bible to the fantasy novels/movies, this creature can be seen frequently in literature and other types of art. Honestly I never thought I’d come across this mythical creature or even something similar, in the “world of science” until last month. When I did, not only I was shocked by the name of the creature but also by the scientist who came up with the concept.
Pierre-Simon Laplace was a French scholar whose work was important to the development of engineering, mathematics, statistics, physics, astronomy, and philosophy. If you’re related of any of these fields mentioned above, you should be well familiarized with his contributions. He’s well known for his contributions in “Bayesian interpretation, Laplace’s equation & Laplace transform, Laplacian differential operator, the nebular hypothesis postulating the existence of black holes and the notion of gravitational collapse. He’s also known as the French Newton or Newton of France. In 1796, Laplace famously published his Exposition of the System of the World, which outlined the mathematical details of what has come to be known as the nebular hypothesis, the theory that the solar system formed billions of years ago from a quickly rotating nebula, or interstellar gas cloud, and that the planets and the sun coalesced from this rotating mass in accordance with the mechanical laws of nature.
Before moving into the question “who is this Laplacian Demon?”, I’d like to introduce you to the concepts of Determinism & Free will, which you will come across in the study of philosophy.
Determinism & free will are basically the opposite of each other. Think of a physics problem you came across regarding a ball rolling along an inclined plane or a canon which moves along an elliptic curve. If the initial conditions are given accurately and if the consequences of other factors like air, gravity is given accurately, you can theoretically predict the future of the ball/canon to a great precision. In other words there’s predictability to the immediate future which might appear as you have some sort of power over what’s going to happen next. We can use the same set of calculations to recall the history of the object. If you stretch this concept to a much broader level, one can argue that everything is predictable. History, Present, Future… Everything is following a set of rules within this given frame of conditions. This is Determinism. In other words, Determinism is the philosophical doctrine that all events including human actions and choices are fully determined by preceding events and states of affairs, and so that freedom of choice is illusory(Source — Collins). Albert Einstein supported this concept. The strange observations on quantum mechanics and other theories were being developed in the early nineteen hundreds and Einstein refused to believe that the behavior of subatomic particles is dependent on “total randomness” which is how it has been described in quantum mechanics. For example, the Heisenberg Uncertainly Principle (which is one of the most interesting theories I’ve ever come across!), says it’s impossible to know both the speed and position of a single particle at the same time. In other words by coming up with this flabbergasting concept Heisenberg proved that we can never know anything for sure! So in quantum mechanics nothing can be certain, and we can only describe things in terms of probabilities. But, Einstein believed that there must be some underlying laws which can be used to determine the state and behavior of all particles. That’s the origin of the famous phrase which is often misunderstood by the general public, “God does not play dice with the universe.”
In 1926, Einstein, in a letter to German physicist Max Born, about quantum mechanics, commented the following:
“Quantum mechanics is certainly imposing. But an inner voice tells me that it is not yet the real thing. The theory says a lot, but does not really bring us any closer to the secret of the “old one.” I, at any rate, am convinced that He does not throw dice.”
In 1943, Einstein, in conversation with biographer William Hermann, concerning what is real and exists versus what is but mental constructs, stated the following:
“Nature doesn’t know chance, it operates on mathematical principles. As I have said so many times, God doesn’t play dice with the world.”
“Free Will” is the concept that all of us are free, all of us have the ability to do whatever we like without being addressed or intervened by some other set of actions occurred before. This contradicts the teachings of determinism where the believe that everything is a result of some other results which took place right before the present situation. Think of this as you going to the mall to buy something and end up buying a lesser quality product of what you have because you didn’t have enough money for the best item. So in this scenario the cause is not having enough money. But what’s the cause for that? Spending too much on something else? Low salary? whatever the reason it might be the interesting fact is that we can always give some explanation for not having the money. According to this concept, free will is false. Everything you do, every movement of an object is deterministic because each of those small small events took place due to something happened before and because of the way it happened! This is the opposite of Free Will.
“The Demon”
Now that we have a good understanding about Determinism , its easy to describe the Demon as Laplace’s summation of the deterministic universe. Think of a Super-intelligent creature who has the knowledge about all the current states, the positions and moments of each and every particle in the universe and how they interact. Then this intellect would be able to analyse this vast amount of data and know every single detail about everything that has existed, exist, and will exist. This gives him the power to see the chain links of the past, present, and future in an unbreakable bond. The interesting fact about determinism is that even this very instance of you reading these words, has a strange yet satisfying connection to cause-and-effect relationships that date back all the way to the beginning of time & it will continue to have its influence in billions of events yet to occur until the end of time. Thus Laplace argued, we can perfectly predict the future and flawlessly retrace the past and all of this will be present before the “its Eyes”.
“We may regard the present state of the universe as the effect of its past and the cause of its future. An intellect which at any given moment knew all of the forces that animate nature and the mutual positions of the beings that compose it, if this intellect were vast enough to submit the data to analysis, could condense into a single formula the movement of the greatest bodies of the universe and that of the lightest atom; for such an intellect nothing could be uncertain and the future just like the past would be present before its eyes.” (Laplace 1902, p. 4)
- A modern version of the defenition of the Laplace’s Demon
But most importantly we must understand that Laplace didn’t actually believe or wanted us to believe that there’s such a god like feature. Napoleon once asked Laplace why there was not a single mention of God in Laplace’s entire five volume explaining how the heavens operated. (Newton, a man of science who believed in an omnipresent God, had even posited God’s periodic intervention to keep the universe on track.) Laplace replied to Napoleon that he had “no need for that particular hypothesis”. Laplace proved that the solar system is stable and does not require divine intervention to keep it from falling apart. (Source-https://physics.weber.edu/carroll/honors/Laplace.htm)
A lot of these come under the Laplace’s Mécanique Céleste (Celestial Mechanics — god-free celestial mechanics). In 1773, Pierre Laplace, in his “Research on the Integration of Differential Equations with Finite Differences and their use in the Theory of Randomness”, is where he has mentioned an early version what would later become, famously, the Laplace’s demon.
What really baffled me at first was this concept of total determinism. What if science really evolve to a stage where we derive the equations for each and every phenomena in the observable universe? What if we finally come up with a theory of everything? Won’t that be the solution to this debate about determinism & free will? Won’t the Laplace’s Demon come alive because of the power of that knowledge? For me, that thought is fascinating. Maybe we’ll understand or get the ability to predict and reevaluate the nature of an event one day. Who knows, sometimes Artificial Intelligence might be the technology to reveal it all. It’s true that at this point free will is the most likely to be true with the recent advancements of the quantum physics. But you never know until we finish studying about the universe. Isaac Newton once said “To myself I am only a child playing on the beach, while vast oceans of truth lie undiscovered before me”. Isn’t that the truth? Even though we know so much about the universe, the amount of knowledge left yet to be uncovered is unimaginably large. Knowledge is relative as everything else in this universe. As I feel, as long as we don’t let that spark of curiosity fade away from our lives, our understanding about this magnificent place called universe, will grow.
One of the two fathers of Calculus, Gottfried Leibniz commented about this nature as follows.
“Everything proceeds mathematically…if someone could have a sufficient insight into the inner parts of things, and in addition had remembrance and intelligence enough to consider all the circumstances and take them into account, he would be a prophet and see the future in the present as in a mirror.”— Gottfried Leibniz (c.1770)
Indeterminism
Today many physicists assert that such a strictly deterministic view cannot do justice to the true nature of the working principle of space. The book, “Dice of the Gods: Causality, Necessity and Chance(1977), by English physicist Werner Ehrenberg can be described as such an attempt to give answers to this debate of determinism & indeterminism of physics. In 1994, Stephen Hawking, during a debate at the University of Cambridge, with Roger Penrose about whether or not Einstein was wrong in his God does not throw dice statement, gave his opinion that:
“Consideration of black holes suggests, not only that God does play dice, but that he sometimes confuses us by throwing them where they can’t be seen.”
As I mentioned above, I never thought that I will come across the term “Demon” in field like physics & mathematics. It made me think about the nature of science & its definitions, about these wonderful scientists who considered it as their duty to uplift the standards of mathematics and I feel it strengthened the bond that I have with science after all. I’ll conclude this article with another quote by Pierre-Simon Laplace asking you to dive in the sea of knowledge and develop your passion for science.
“Present events are connected with preceding ones by a tie based upon the evident principle that a thing cannot occur without a cause which produces it. This axiom, known by the name of the principle of sufficient reason, extends even to actions which are considered indifferent; the freest will is unable without a determinative motive to give them birth; if we assume two positions with exactly similar circumstances and find that the will is active in the one and inactive in the other, we say that its choice is an effect without a cause. It is then, says Leibnitz, the blind chance of the Epicureans. The contrary opinion is an illusion of the mind, which, losing sight of the evasive reasons of the choice of the will in indifferent things, believes that choice is determined of itself and without motives.” (Laplace 1902, pp. 3–4)
