Does the Schrödinger Equation Imply a Deterministic Universe?

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In summary, a deterministic universe is one that suggests all events are caused by prior events and can be predicted. This differs from the concept of free will, which suggests individuals have the ability to make choices independent of prior events. The debate over whether the universe is truly deterministic is ongoing, with some arguing that the laws of physics support determinism while others point to the unpredictable nature of quantum mechanics. The concept of determinism also raises questions about morality and responsibility, with some arguing that it undermines the idea of free will and personal responsibility. However, there is currently no concrete evidence to prove or disprove determinism, making it a topic open to debate and interpretation.
  • #1
Physics Slayer
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Does quantum mechanics imply a deterministic or non deterministic model of the universe?
The entire universe has a single very complicated wave function ##\psi##, and if we plug this into the schrödinger equation will that mean we live in a deterministic universe? (whatever happens and will happen was already predetermined at the time of the big bang. the initial conditions of the universe, i.e. ##\psi(t=0)## was set at this time)As the schrödinger equation will tell us how the wave function will evolve, will that mean that a theoretical creature like Laplace's demon could see the future and the past?

I have heard people before Quantum Mechanics believed that everything was deterministic and that we have no free will, if we knew the forces acting on every particle we could theoretically construct the the future and peer into the past, but once we got to know about the fundamentally random collapse of the wave function, this model of a deterministic universe could not hold anymore?

I am not sure if I am allowed to ask about free will(on a science forum, it's more philosophy?).
 
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  • #2
Physics Slayer said:
Summary:: 1. Does quantum mechanics imply a deterministic or non deterministic model of the universe?

2. The entire universe has a single very complicated wave function ##\psi##, and if we plug this into the Schrödinger equation will that mean we live in a deterministic universe? (whatever happens and will happen was already predetermined at the time of the big bang. the initial conditions of the universe, i.e. ##\psi(t=0)## was set at this time)As the schrödinger equation will tell us how the wave function will evolve, will that mean that a theoretical creature like Laplace's demon could see the future and the past?

I have heard people before Quantum Mechanics believed that everything was deterministic and that we have no free will, if we knew the forces acting on every particle we could theoretically construct the the future and peer into the past, but once we got to know about the fundamentally random collapse of the wave function, this model of a deterministic universe could not hold anymore?

3. I am not sure if I am allowed to ask about free will(on a science forum, it's more philosophy?).

Some big questions in here! :smile: And each is good for many a debate.

1. Generally speaking, what we know about QM implies a non-deterministic universe. There are interpretations of QM in which determinism is maintained (Bohmian Mechanics being the best known of those). I would recommend checking out the Quantum Interpretations and Foundations subforum to learn more. That is the proper spot to discuss those.

https://www.physicsforums.com/forums/quantum-interpretations-and-foundations.292/2. Although the Schrödinger itself is deterministic, it cannot be used to predict the outcome of any specific experiment when the probability is not certain (0 or 1). In those cases, experiments show that outcomes are random as best as anyone can tell. There does not appear to be any information available to us to predict outcomes, and theory offers us no particular hope that such information might be discovered in the future. (Of course, anything is possible.)

Don't forget that we have the Heisenberg Uncertainty Principle as well. That limits knowledge about non-commuting properties of quantum systems.3. Keep the discussion about free will in the Interpretations subforum alongside discussions that relate to the science, and you should be fine.
 
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  • #3
Physics Slayer said:
Summary:: Does quantum mechanics imply a deterministic or non deterministic model of the universe?
It depends on which interpretation of QM you adopt; some (such as the MWI or the Bohmian interpretation) are deterministic, while others (collapse interpretations) are not.

As @DrChinese has already mentioned, discussions of QM interpretations belong in the interpretations subforum, not here.

As far as practical applications of QM go, they have to treat things as non-deterministic since we can't use QM to predict exact experimental results in general.

Physics Slayer said:
I am not sure if I am allowed to ask about free will(on a science forum, it's more philosophy?).
Free will discussions in general are philosophy and are off topic in the science forums here. (You might be able to discuss it in General Discussion.)

Free will discussions in the context of specific papers on QM interpretations that take some definition of "free will" and apply it to some QM interpretation are permissible in the interpretations subforum, although they still get moderated carefully.
 
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  • #4
Physics Slayer said:
I have heard people before Quantum Mechanics believed that everything was deterministic and that we have no free will...

We don't have "free will" (as normally understood by people) either in a stochastic universe...😉
 
  • #5
mattt said:
We don't have "free will" (as normally understood by people) either in a stochastic universe...😉
As has already been pointed out in response to the OP, discussions of free will are in general off topic in the PF science forums. That includes this thread.
 

Related to Does the Schrödinger Equation Imply a Deterministic Universe?

1. What is a deterministic universe?

A deterministic universe is a concept in which all events and outcomes are predetermined and can be predicted with complete accuracy based on the initial conditions of the universe. This means that everything that happens in the universe is the result of a chain of cause and effect, and there is no room for randomness or free will.

2. How does determinism relate to scientific theories and laws?

Determinism is closely related to scientific theories and laws as it suggests that the laws of nature govern all events and phenomena in the universe. This means that scientific theories and laws are based on the idea that there is a cause and effect relationship between all things, and that the universe operates in a predictable and orderly manner.

3. Is there any evidence for a deterministic universe?

There is currently no definitive evidence for a deterministic universe. While some scientific theories and laws may support determinism, there are also theories and phenomena that suggest the existence of randomness and unpredictability in the universe. Additionally, the concept of free will also challenges the idea of a completely deterministic universe.

4. Can determinism coexist with the concept of free will?

The question of whether determinism and free will can coexist is a highly debated topic among philosophers and scientists. Some argue that if the universe is deterministic, then free will is an illusion. However, others suggest that free will may still exist within a deterministic framework, as our actions and choices are still the result of a chain of cause and effect.

5. How does the concept of a deterministic universe impact our understanding of the world?

The idea of a deterministic universe has significant implications for our understanding of the world. It suggests that everything that happens, including our thoughts and actions, is predetermined and not the result of our own choices or agency. This challenges our traditional notions of free will and raises questions about the nature of reality and our place in the universe.

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