The Causality Problem and Tunneling: An Overview

In summary, the causality problem refers to the idea that an effect cannot occur before its cause. In classical dynamics, this is questioned when there are forces that depend on acceleration derivatives with respect to time. Tunneling is a quantum effect where there is a non-zero probability for a particle to pass through a finite width potential barrier, even if its energy is less than the barrier. This is only possible in a quantized system. The probability of passing through can be seen as the probability of finding the particle anywhere between the point it exits the barrier and infinity. The potential barrier must have a finite width and height for tunneling to occur, as an infinitely high barrier would result in a "delta potential problem".
  • #1
Phymath
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0
the causality problem and tunneling?
 
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  • #2
Phymath said:
the causality problem and tunneling?

Tunelling is a quantum effect which consists in the existence of a non zero probability of that a point particle with energy E passes through a finite width potential barrier V(x)>E .

The causality of physical phenomena states that the effect cannot precede the cause.In classical dynamics,causality is questioned whenever forces that depend of the acceleration derivatives wrt to time appear.I would infer you to the analysis of the Abraham-Lorentz equation in the classical electrodynamics (can be found in Jackson...)

Daniel.
 
  • #3
still unclear on the tunneling I am not fimilar with non zero probability (do u mean of being in a location?) and finte width potential Barrier
 
  • #4
Phymath said:
still unclear on the tunneling I am not fimilar with non zero probability (do u mean of being in a location?) and finte width potential Barrier

Classically,the particle has no chance to penetrate that potential barrier,as its energy is less than the barrier's.But QM proves that this becomes possible (has a non zero probability (do u know what probabilities are...?)) once the system is quantized.Yes,the probability of passing through could be seen as the probability of finding the particle anywhere in the semiinfinite interval between the point at which the particle exits the potential barrier and the +infinity on the axis describing the direction of movement.I assumed the particle comes from -infinity.That's why the potential barrier must be finite,both as width and as height.If it wasn't finite along the "x" axis (if it didn't have a finite width),we would not be speaking about the tunnel effect.If it were infinitely hight,we would not speak about tunnel effect,but about "delta potential problem".

I hope it's clear.
 

Related to The Causality Problem and Tunneling: An Overview

1. What is the causality problem?

The causality problem refers to the conflict between the principle of causality, which states that every effect has a cause, and the phenomenon of tunneling, in which particles can appear to travel faster than the speed of light and seemingly violate causality.

2. How does tunneling occur?

Tunneling occurs when a particle with insufficient energy to overcome a potential barrier appears on the other side of the barrier without crossing it. This is possible due to the probabilistic nature of quantum mechanics, where particles can exist in multiple states simultaneously.

3. What is the role of the uncertainty principle in the causality problem?

The uncertainty principle states that the position and momentum of a particle cannot be known simultaneously with absolute certainty. This means that the exact location and velocity of a particle that has undergone tunneling cannot be determined, making it difficult to determine whether causality has been violated.

4. Can the causality problem be resolved?

There is currently no definitive answer to the causality problem. Some theories, such as the many-worlds interpretation of quantum mechanics, suggest that tunneling does not violate causality as it creates parallel universes in which all outcomes are possible. Other theories propose that causality may need to be redefined in the context of quantum mechanics.

5. What are the potential implications of the causality problem and tunneling?

If causality is found to be violated by tunneling, it could have significant implications for our understanding of the fundamental laws of physics and our ability to predict and control events. It could also potentially lead to the development of new technologies based on quantum tunneling, such as quantum computers.

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