Classical and quantum physics.

In summary, the differences between quantum physics and classical physics can be demonstrated through various examples such as the Bell inequalities experiment, quantum tunnelling, and the behavior of objects passing through a slit. These examples show that classical laws, such as Newton's first law, do not apply at the quantum level. Additionally, comparing the solutions of the harmonic oscillator in both classical and quantum mechanics further highlights the distinctions between the two theories.
  • #1
Dorilian
25
0
What could be a good example or textbook problem which could be solved using quantum physics and classical physics in order to see the difference?

If you wan to explain the differences to a non-physics student, what would you do? (Don´t use the blackbody radiation problem).
 
Physics news on Phys.org
  • #2
How about the fact that atoms are stable?
 
  • #3
niklaus said:
How about the fact that atoms are stable?

Good, are there any more examples?
 
  • #4
Dorilian said:
What could be a good example or textbook problem which could be solved using quantum physics and classical physics in order to see the difference?

If you wan to explain the differences to a non-physics student, what would you do? (Don´t use the blackbody radiation problem).

The standard example is an experiment for testing the Bell inequalities.
 
  • #5
Dorilian said:
What could be a good example or textbook problem which could be solved using quantum physics and classical physics in order to see the difference?

If you wan to explain the differences to a non-physics student, what would you do? (Don´t use the blackbody radiation problem).

The standard example is an experiment for testing the Bell inequalities.

Much more difficult to calculate but much more interesting is the spectrum of an electron surrounding a proton.
 
  • #7
Dorilian said:
What could be a good example or textbook problem which could be solved using quantum physics and classical physics in order to see the difference?

If you wan to explain the differences to a non-physics student, what would you do? (Don´t use the blackbody radiation problem).

Consider an object moving through a slit in a wall.

Assuming no forces acting anywhere, a classical object, like a bullet, say, passes straight on through in a straight line. This is Newton’s first law at work. If we repeat the experiment many times we always get the same result – the bullet always goes straight ahead. It is never deflected away from straight line motion. This classical behavior has been observed in many experiments.

But a quantum object does get deflected as it passes through a slit, even when there are no forces acting. And if we repeat the experiment we do not always get the same result. The particle can be scattered in many different directions. This quantum behavior has been observed in many experiments. There is no classical explanation for this. We only know that Newton’s laws do not work at the quantum level.

The classical calculation is trivial. The quantum calculation is not trivial, but doable.
Best wishes
 
  • #8
The equation for the harmonic oscillator can be solved in classical mechanics and the Schrodinger equations for the quantum harmonic oscillator can be solved. Many comparisons can be made. In the classical case the motion is oscillatory in the quantum mechanical there are stationary states, those with exact value of energy.
 

What is the difference between classical and quantum physics?

Classical physics deals with the behavior of macroscopic objects, while quantum physics deals with the behavior of subatomic particles. Classical physics follows the laws of classical mechanics, while quantum physics follows the laws of quantum mechanics.

How do classical and quantum physics explain the behavior of light?

Classical physics explains light as a wave, while quantum physics explains it as both a wave and a particle. This is known as wave-particle duality.

What is the uncertainty principle in quantum physics?

The uncertainty principle states that the more precisely the position of a particle is known, the less precisely its momentum can be known, and vice versa. This is a fundamental principle in quantum mechanics that limits our ability to precisely measure certain properties of particles.

What is the role of probability in quantum physics?

In classical physics, outcomes of experiments are determined and predictable. In quantum physics, the behavior of particles is described by probabilities, meaning that we can only predict the likelihood of a certain outcome, rather than a definite result.

How do classical and quantum physics contribute to our understanding of the universe?

Classical physics helps us understand the behavior of macroscopic objects, while quantum physics helps us understand the behavior of subatomic particles. Together, they form the basis of our understanding of the physical laws that govern the universe at both the macroscopic and microscopic levels.

Similar threads

Replies
6
Views
767
Replies
26
Views
2K
  • Quantum Physics
Replies
21
Views
2K
  • Quantum Physics
Replies
9
Views
727
  • Quantum Physics
Replies
21
Views
1K
Replies
3
Views
776
  • Quantum Physics
Replies
7
Views
1K
Replies
4
Views
1K
  • Quantum Physics
5
Replies
143
Views
5K
Back
Top