Quantum vs. Classical Mechanics

Classical and quantum mechanics are the two main fields of mechanics in physics.Classical mechanics came a few hundred years before Quantum mechanics.Subsequently it is less accurate and less reliable then the more recent mechanic field of quantum mechanics.Despite being outdated,Classical mechanics can still be used for many everyday problems with bigger and slower moving objects.However,when dealing with extremely fast moving or small subatomic particles a Classical approach will not produce sufficiently accurate results as was the case around the 19th century.

Difficulties with the Classical mechanics theory came right around the 19th century.First was the Ultraviolet Catastrophe.Experimental data when testing black body radiation was found to be inconsistent with Classical mechanics.The data showed that as the wavelength of the incoming radiation approaches zero,the amount of energy being radiated also approaches zero,whereas Classical mechanics says the emitted energy is infinite.The second difficulty with the theory was its inability to correctly describe the photoelectric effect.The photoelectric effect says that photons from a surface are released when light hits it.Classical mechanics says that electrons will be emitted from a metal by light waves with any frequency as long as the intensity of the light is strong enough, and even it is weak over a long enough period of time electrons will eventually be emitted.The theory was proved incorrect after experiments showed that light under certain frequencies did not produce the photoelectric effect on the metal,which meant that the emitting of electrons is related not to intensity but the waves frequency.A new string of mechanics,Quantum mechanics,was created in order to resolve the incompatibilities of Classical mechanics.A main difference between the two fields of mechanics is the make up of the atom.In Quantum mechanics electrons in an atom are outside of the nucleus in specific orbitals around the nucleus that they can jump from one to another only when a specific energy level is reached,and can never be in-between the specific orbitals.Also Quantum mechanics says that a photon is released only when an electron jumps from a higher energy level to a lower energy level,or a higher energy orbital to a lower energy orbital.Classical mechanics,contradicting this,says that an atom is constantly emitting radiation.Quantum mechanics describes light as both as a wave and a particle,depending on the situation.Light exhibits interference and diffraction,which are both characteristics associated to waves.However,there is also evidence that supports the particle theory of light that states electromagnetic waves consist of photons and bursts that have momentum and energy.

The Uncertainty Principle is also described by Quantum mechanics.It says,contrary to Classical mechanics belief that precision is limited only by the accuracy of man made instruments;it is impossible to make simultaneous measurements of a particle's position and momentum with infinite accuracy.This essentially is saying that the more we know about one,momentum or position,the less we will know about the other.

For most problems Classical mechanics is a more practical method to use.Despite not being as accurate as Quantum mechanics,the math is much simpler and the inaccuracies are generally small enough not to be a factor.Quantum mechanics is only necessary when dealing with extremely fast moving particles or small particles.