Hi guys! In this post we're going to consider whether we can predict anything, everything or nothing at all about the future!
The film Minority Report centres on the plot-line that the government are able to predict the future and whenever there will be a murder or other crime committed, the government's Oracles detect it. Protagonist cool cop Tom Cruise (from the Pre-Crime unit) predicts the where, the when and the how of the to-be murder and gets to the victim before the to-be murderer... Another film about the future is the Hindi film Krrish, a film about a country boy-turned-superhero who goes up against a sinister scientist who has built a computer that can see the future. The future in Krrish, however, is inevitable and unchangeable, unlike the future in Minority Report.
What do we need to predict the future? Well, to know the state of the universe in the future, we need to know 2 things:
How one state of the universe changes to another (laws of physics) and
The starting state (all properties of all matter in the universe at one point in time).
We do not know all laws of physics, but we know enough to simulate a universe with great accuracy. For example, Angry Birds gameplay does not encode for all laws of physics (air resistance, friction, etc.) but can still simulate how a Red bird flies through the air and hits the weak structures of the pigs with great accuracy and can also predict how the structure breaks/falls. In Angry Birds, however, we know the order in which the birds are initially arranged, how the pigs' structure is composed (shapes/materials, etc.) at the start and how much you pull back the slingshot to launch each bird. So, to simulate the Angry Birds universe, that is to make viable predictions in that model, we need to know the state of everything in the model at the start. Extending that premise, in another context, we need to know the initial state data of the universe to predict the universe's fate!
This is too much to handle! How can we possibly collect all the data (describing atom configurations, macroscopic velocities, air molecule motion, etc.) in the world, let alone the universe? But assuming that we do collect all the yottayottayotta....yottabytes of data, we still would not be able to properly simulate our universe. Why? It is all to do with the key principle of quantum mechanics: Upon studying the state of a system, we change it. Even if we could collect all the data in the world, the space-time trajectory of the world (the world's world-line ... he-hey...) is changed the instant we collect it. 😮
Even assuming that we could find the data without disturbing the universe, we still could only guess what the future holds. As we go farther into the future, our certainty plummets. Why is this? Quantum interactions are not certain, as the very location, energy and momentum of the interacting particles cannot be known with certainty (Heisenberg's uncertainty principle). Quantum interactions are what makes the world go round (no, seriously, without the gluon of the nuclear strong force interacting on quarks, the Earth would only be a figment of our imagination - and so would we, come to think of it...). The friction in a chair (electrical forces between subatomic particles causing surfaces to microscopically 'leap'), random human choice (spins of electrons in synapse gaps) and many other everyday phenomena can clearly be seen to be dominated by the quantum world.
We cannot therefore predict the future. Not with complete certainty. But we can get an inkling! Some overall indication of what is going to happen, akin to a blurry monochromatic image instead of a high-res, full colour render. Like the weather(wo)man predicting the weather, we can estimate quite assuredly. The weather(wo)man does not have to describe where each raindrop will fall or where each cloud will cast a shadow, only where in the country it is going to rain and where it is going to be cloudy. Similarly, instead of predicting the path of every displaced air molecule when a vase falls, we only have to predict whether the vase will fall and where. We cannot be certain about the future, but the laws of physics will allow us a glimpse, albeit blurry. Having an idea of what is to come is not therefore out of our grasp.
And also, on a side note, to guess and to predict are different things. Prediction is constrained to the future but guesswork is for all time.
Anyway, I predict I might C u again soon in my next post!