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SeventhSigma

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- Thread starter SeventhSigma
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In summary: Everything is random at the quantum scale, but on a macroscopic level, it's pretty much deterministic. It's still random, but deterministic in the sense that the variance attributable to quantum events is vanishingly small.

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SeventhSigma

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- #2

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It's also difficult to define randomness in a meaningful way. The evolution of a wavefunction according to the Schrodinger equation is completely deterministic. There is no randomness in the many-worlds interpretation.

IMO there is no meaningful answer to your question unless you refine it by defining more clearly what you mean.

- #3

SeventhSigma

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Therefore, we've always said "it's possible" to materialize on the other side of the moon, but we say it's super improbable because the position function for anyone particle becomes crazy unlikely when we're talking about a distance that large (untold standard deviations away), and also unlikely when you consider that ALL particles of your body would have to do this at once, etc.

In other words, on macroscopic levels, we're not *fully* deterministic -- but even in systems where we can predict outcomes with virtually 100% accuracy, the quantum unpredictability will have little impact on the unexplained variance.

- #4

BruceW

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Defining when measurement happens is tricky. A good rule is to say that if the resulting state vector can practically be returned to the original state vector, then measurement has not yet occurred.

When a classical object gets entangled with the quantum state, the state vector now describes a many-particle state which is practically impossible to write down. Therefore measurement happens when a classical object gets entangled with the original state.

So the 'randomness' gets brought in when the quantum system interacts with a classical object. The classical object could be a Geiger counter, or a cat, or the air around us.

So the quantum state evolves deterministically due to the Schrodinger equation, until a classical object makes a measurement, which causes state reduction (which is non-deterministic).

There is another interpretation called many-worlds, where state reduction never happens, so everything is deterministic in many-worlds interpretation.

Quantum mechanics is a branch of physics that deals with the behavior of matter and energy at a very small scale, such as atoms and subatomic particles. It explains how particles behave and interact with each other at the quantum level.

No, quantum mechanics does not state that everything is random. It describes the behavior of particles in terms of probabilities, meaning that certain outcomes are more likely than others, but it does not rule out the possibility of determinism.

Quantum mechanics explains randomness through the principle of uncertainty, which states that it is impossible to know both the position and momentum of a particle at the same time. This leads to the probabilistic nature of quantum mechanics, where the exact outcome of any measurement cannot be predicted.

No, quantum mechanics and chaos theory are two different scientific theories. Quantum mechanics deals with the behavior of particles at a very small scale, while chaos theory deals with the behavior of complex systems. However, both theories involve elements of randomness and unpredictability.

Quantum mechanics has a wide range of practical applications, including the development of new technologies such as transistors, lasers, and computer memory. It also plays a crucial role in fields such as chemistry, materials science, and cryptography.

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