Classical vs Quantum mechanics

Since we are part of the universe, can we ever truly know if it has a cause or not? In summary, the question of whether the universe has a cause is not well-defined in either classical or quantum mechanics. The main conceptual difference between the two is the existence of the quantum of action, which makes it impossible to combine causal and spacetime descriptions. The Kalam cosmological argument, which states that everything that begins to exist must have a cause, is often used to argue for the existence of an intelligent cause, but it is a weak argument as the cause is usually considered an exception to the premise without evidence. It is also uncertain whether the universe even had a beginning or if time can truly "begin". Ultimately, it may be impossible
  • #1
Laptu
Which is better at determining whether the universe has a cause? From my basic understanding, quantum mechanics is generally accepted to be indeterministic whereas classical mechanics is deterministic. Posted in the philosophy question because this is related to the first premise of the Kalam cosmological argument i.e. whatever beings to exist must have a cause. The obvious answer to me seems like classical mechanics due to the fact that it operates at a macroscopic scale. But, want to see others opinion.
 
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  • #2
I would say Quantum Mechanics.

Quantum mechanics, also known as quantum physics or quantum theory, is a branch of physics providing a mathematical description of the dual particle-like and wave-like behavior and interaction of matter and energy. Quantum mechanics describes the time evolution of physical systems via a mathematical structure called the wave function.
Source: http://en.wikipedia.org/wiki/Quantum_mechanics

Seems to be more fit than Classical Mechanics.

In physics, classical mechanics is one of the two major sub-fields of mechanics, which is concerned with the set of physical laws describing the motion of bodies under the action of a system of forces. The study of the motion of bodies is an ancient one, making classical mechanics one of the oldest and largest subjects in science, engineering and technology.
Classical mechanics describes the motion of macroscopic objects, from projectiles to parts of machinery, as well as astronomical objects, such as spacecraft , planets, stars, and galaxies.
Source: http://en.wikipedia.org/wiki/Classical_Mechanics
 
  • #3
"Does the universe have a cause" is not really a well defined question neither in classical nor quantum mechanics. However, the main conceptual difference between quantum mechanics and classical mechanics is indeed the fact that the existence of the quantum of action makes it impossible to combine unrestrictedly the causal and spacetime descriptions. In classical mechanics, it is assumed that a system may be observed without disturbing it appreciably. However, the quantum implies that any observation of a system involves an interaction with the measuring instruments which cannot be neglected. Thus, neither the system nor the agencies of observation can be ascribed an independent reality in the ordinary sense. The definition of the state of a system claims the elimination of all external disturbances, and so, because of the quantum, any observation will be impossible, and the concepts of space and time lose their immediate sense. On the other hand, if we permit interactions with measuring bodies, and unambiguous definition of the state is no longer possible, and hence the causal mode is no longer applicable. Thus, in quantum theory, causality and spacetime coordination are complementary.
 
  • #4
Laptu said:
this is related to the first premise of the Kalam cosmological argument i.e. whatever beings to exist must have a cause

The KCA is easy to refute as an argument. The argument goes;

1) Everything that begins to exist has a cause

2) The universe began to exist

C) The universe has a cause

Premise 1 is dodgy because firstly it has not been proven and secondly proponents usually say that the universes cause does not apply. It is a weak argument to say that this cause must be an exception to the premise with no evidence.

Premise 2 is also dodgy because it is unknown if the universe began at all (it could be an infinite, cyclic universe). There's also the problem of definition, can time ever "begin".

Lastly the conclusion doesn't get you anywhere, yes it is a good conceptual question that can lead us to do good science in an attempt to explain if the notions of "before" and "cause of" the big bang. However as the KCA is usually used to promote the existence of an intelligent cause it is rarely used to invoke good reasoning, usually the argument goes "the universe must have a cause therefore god".
 
  • #5
Laptu said:
Which is better at determining whether the universe has a cause? From my basic understanding, quantum mechanics is generally accepted to be indeterministic whereas classical mechanics is deterministic. Posted in the philosophy question because this is related to the first premise of the Kalam cosmological argument i.e. whatever beings to exist must have a cause. The obvious answer to me seems like classical mechanics due to the fact that it operates at a macroscopic scale. But, want to see others opinion.

The universe is by definition "all that exists" and, therefore, any causal agent separate from the universe would defy logic and the law of identity. For either theory to be more applicable would require that you at least first create clearer definitions of the terms.
 
  • #6
Don't virtual particles refute the first premise??
 
  • #7
I don't think either classical or quantum mechanics would be better at answering this question. After all, quantum mechanics is just classical mechanics in the limit as 0 approaches h. Put another way, if the graininess of particles is orange, and the repetitiveness of waves is yellow, then wave-particle duality is nothing more than amber waves of grain
 
  • #8
Nothing in the universe is ever created out of nothing and without a cause. This seems to imply, to me at least, that the universe has either always existed, or was created out of something that existed prior to the universe. Of course it may be possible that the universe was created out of nothing as well, as that can't be ruled out either since we cannot observe everything in the entire universe at all points in time and we may have just "missed" seeing a particle created from nothing. Hmm...looks to me like trying to apply logic to this problem gets us absolutely nowhere.

I think a better question is can we can even determine if the universe has a cause. If so, what would we look for?
 

Related to Classical vs Quantum mechanics

1. What is the main difference between classical and quantum mechanics?

The main difference between classical and quantum mechanics is the level of accuracy with which they can predict the behavior of particles. Classical mechanics is based on deterministic equations that can accurately predict the position and velocity of particles, while quantum mechanics is based on probabilistic equations that can only predict the probability of a particle's position or velocity.

2. How do the principles of classical mechanics differ from those of quantum mechanics?

The principles of classical mechanics are based on Newton's laws of motion and the conservation of energy, while the principles of quantum mechanics are based on the wave-particle duality of matter and the uncertainty principle. In classical mechanics, particles are treated as distinct objects with definite properties, while in quantum mechanics, particles are described as waves with probabilistic properties.

3. What are the limitations of classical mechanics compared to quantum mechanics?

Classical mechanics is limited in its ability to accurately predict the behavior of particles at the atomic and subatomic level. This is because classical mechanics does not account for the wave-like nature of particles and the inherent uncertainty in their position and velocity. Quantum mechanics, on the other hand, can accurately predict the behavior of particles at all scales.

4. How do classical and quantum mechanics explain the behavior of macroscopic objects?

In classical mechanics, macroscopic objects are treated as a collection of particles, and their behavior can be accurately predicted using deterministic equations. In quantum mechanics, macroscopic objects are described as a collection of particles with wave-like properties, but at the macroscopic scale, these wave-like behaviors become negligible and the objects behave according to classical mechanics.

5. What are some real-world applications of classical and quantum mechanics?

Classical mechanics has been used to develop technologies such as airplanes, cars, and bridges, while quantum mechanics has led to the development of technologies such as transistors, lasers, and MRI machines. Additionally, quantum mechanics is essential for understanding the behavior of materials at the nanoscale, leading to advancements in fields such as nanotechnology and materials science.

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