From a physics point of view, given that an event may spark a new event, and if we could track every event in the past to predict the events in the future. Are there real random events out there?
I have wild thoughts about this, but I don’t know if there are real theories about this with serious maths.
For example, I get that we would need a computer able to process every event in the past (which is impossible), and given that the computer itself is an event inside the system, this computer would be needed to be an observer from outside the universe…
Man, is the universe determined? And if not, why?
Sorry about my English and thanks!
Comments
Kinda but not really. Quantum effects are probabilistic, meaning there are multiple possible outcomes but they happen randomly (according to their probabilities).
The short answer is no, because quantum mechanics. Up through the Classical era, all indicators showed that the universe could be deterministic – but with the advent of quantum mechanics, and specifically the Heisenberg Uncertainty Principal, we discovered that it is impossible to precisely know the speed or position of anything simultaneously.
If you can’t know the precise starting conditions of a system, then it can’t be deterministic.
There are real random events. Look up the Copenhagen interpretation of quantum physics, specifically the Born Rule. It turns out indeterminacy can be found in nature (despite Einstein saying this is only ad hoc).
However, this alone wouldn’t be enough to prove an entirely indeterministic (or deterministic) universe.
The answer is don’t think about it.
I used to be a hardcore determinist but I’m not so hardcore now. Just regular core.
> I have wild thoughts about this
Related subject, Kurzgesagt has this nice video about free will some time ago: https://www.youtube.com/watch?v=UebSfjmQNvs
Watch and tell us what you think 🙂
In short: We don’t know.
There are two parts of your question:
Is the universe deterministic in the sense that anything we can observe behaves, in theory, following stringent laws of physics? Well, maybe. For the physics we typically know and understand, a lot is pointing to ‘yes’. But we can’t really say that we’ve fully uncovered all of these rules.
Is the universe deterministic in the sense that, if the answer to the above is ‘yes’, we can in principle predict anything and all things, if we have enough information and a large enough computer? No. Simply put, there are things we cannot know. Like for instance, you cannot know the exact location *and* direction of e.g. a photon at the same time. This relates to Heisenberg’s principle of uncertainty. So even IF everything moves according to fixed laws, there are lots of stuff we can’t calculate, even if we knew those laws in the first place.
Could be – impossible to determine. Probably no.
Consider a radioactive isotope of an element with a half life of 100 years (half of it would have decayed in that period).
Now we look at one single molecule.
There is no timer on it of when it would decay and throw off a particle. Just a continuous random chance.
…or is there an internal clock that operates in a way we can’t know, where, by its very creation, the exact time of that atom’s decay was set?
Just one example, without going deep into a world of physics that seems made of micro-decisions of chance.
This is really one of the fundamental questions of the universe and we don’t know the answer yet. There are two main things that are interesting to talk about here.
One is the uncertainty principle. It may seem like, if we just knew the starting conditions of every particle in the universe, its velocity and momentum and all its other features, and if we had a powerful enough supercomputer, we could compute all the future states of the system. Unfortunately the uncertainty principle says that it is impossible to know all the information about a particle all at once, so it may not actually be possible to do this kind of simulation.
Second is the idea of quantum superposition. In a nutshell, this says that particles can be in a situation where one of its attributes is undetermined. Some particles have a property called “spin” for example that can be either “up” or “down”, and sometimes when they interact with another particle they have a chance afterwards of spinning up, and a chance of spinning down. And quantum superposition says that until the spin is determined, it’s actually both up and down at the same time. This seems like a wild result, but experiments seem to be showing that it’s true – the 2022 Nobel prize was awarded for an experiment that proved that the particle isn’t “secretly” in the up state or down state and we just don’t know which – it really does seem like it is in both states at the same time. How we interpret this result is an open question in physics, but either way it puts a huge wrench into this “define all the attributes and then compute the final states” argument, because some attributes are able to be in multiple states at the same time.
So, overall, it seems like the fundamental universe might not be deterministic. But it’s also worth bearing in mind when you’re thinking about this, that the fundamental finding of quantum mechanics is that the rules that apply to really tiny stuff in the universe are very very weird. You can’t use your intuition based on the world around you to analogise to it, because it’s so strange.
We dont know. The majority consensus is the Copenhagen Model which posits that the universe is inherently nondeterministic due to the nature of quantum mechanics. There are other theories though, and some with plausible math that go against this and contend the universe really is deterministic; pilot wave and superdeterminism for instance.
In ALL cases I’m aware of, it is not possible within the system to have universal knowledge such that you could calculate the future even if it was deterministic. Quantum interactions may or may not be actually probabilistic, but from within they will appear to be regardless. Deterministic doesn’t mean determinable.
At a small scale (say, atomic and smaller), quantum effects are random, but the probability functions that describe the randomness are well understood and behave in a deterministic way. The result is that the universe is effectively deterministic at a macro scale. (There are some edge cases where quantum effects become important at larger scales, but they are not really important here).
An ELI5 example: if you flip a coin, the result is random but the probabilities are not. So if you flip ten coins, you might have 70% heads and 30% tails one time and 40%/60% another time. But if you flip ten trillion coins you are going to end up with 50%/50% every time. It’s not because it’s impossible to have skewed results, but because it is so unlikely. For the same reason, you never see your dinner quantum tunnel through the table and fall on the floor, but a single particle can randomly “teleport” to the other side.
All that being said, there is so much complexity in the world, there are many emergent phenomena: things that happen that are surprising even when we understand what’s happening “under the hood”. For example, we know how gases behave and all the gas molecules bouncing around the atmosphere are behaving in a deterministic manner, but we can’t predict the weather very well.
First, this is the working definition of determinism being used:
>the philosophical doctrine that all events, including human action, are ultimately determined by causes regarded as external to the will.
All signs indicate we live in a universe governed by cause and effect. Human behavior is a matter of biology, which is a matter of chemistry, which is ultimately a matter of physics. All effects are inevitable given their causes. There’s no choice to override the outcome of physics.
Now, no one is in a position to know a current state of the universe and make predictions. Not only would measurements change what was being observed, there is no conceivable way to store enough data to represent the complexity of the universe let alone run predictive computations on that immense data set.
So all effects in the universe are brought about (determined) by their causes, but there is no conscious entity capable of predicting (determining) outcomes in advance. Any confusions that come about are likely due to the imprecision of the language.
This gigantic computer that you’ve come up with is a well-established thought experiment in the philosophy of science. In that domain, we call it Laplace’s Daemon.
The idea is, it’s a supernatural being that sits completely outside of the universe and can inspect every part of it in infinite detail and compute in its head the laws of physics to predict how the universe will evolve over time.
Whether or not Laplace’s Daemon would be able to perfectly predict the future is the same as asking whether or not the universe is deterministic.
Quantum mechanics has made this less straightforward to answer. There are a few different takes people have. On its face, it appears that we as scientists cannot predict the outcomes of certain kinds of quantum events.
However, we are not Laplace’s Daemon. Not because we can’t calculate these interactions. But because we are not outside the universe. According to the math we use in computing how quantum mechanical systems evolve, the outcomes of these events are deterministic. But when we measure them, we perceive randomness. How could that be?
The best understanding we have to explain that mismatch is that the universe is objectively deterministic however, being inside the universe limits us to only be able to see a part of it which gives the subjective appearance of randomness. Specifically, when a scientist interacts with a specific type of quantum system (a superposition), they too go into superposition. A superposition is a system that is in two states at once. So when the scientist “measures” which state the system is in, they scientist goes into a state of measuring both outcomes — with each version of the outcome continuing to go on in its own world having measured one but not the other result.