When we look at physics there are various theories and ideas. In this post we will look at the limits of Classical Mechanics and how Quantum Mechanics can fill in the gaps that Newtonian Mechanics (another name for Classical Mechanics) seems to have left open or unexplained.
Blackbody Radiation:
To understand this concept the first thing to know is that everything that has a temperature above absolute zero will release light –
even pitch black objects (their light is created by blackbody radiation).
Classical Mechanics approached blackbody radiation by
stating that light is formed by waves that are made via vibrations. The hotter
the object, the more the kinetic energy, or the faster the vibration of electrons resulting in the production of more light. This all makes perfect sense; however, the
picture posted directly under the title of this section is where classical
mechanics falls short. According to classical mechanics all frequencies have
the same energy. This is wrong as we can see when we look at the picture of the
experimentally calculated values. So, how does this make any sense? Bring in
quantum mechanics! We talked about Planck’s constant so now we are going to talk
about the man behind this number, Max Planck. Planck came up with a quantum (or in layman terms a group of energy), the size of any quantum is dependent on the vibrating
frequency of the electrons.
His equations: energy = Planck’s
constant x frequency
The explanation: the energy of the electron can be
multiplied by any integer but the electron needs to have at the minimum one
quantum of energy to vibrate. Without this single quantum of energy the thing
will NOT light up. Going back to the picture, the higher frequencies have too
much quantum energy so the vibrations are unable to actually commence!
Hydrogen Atom:
Everybody asks about the good old hydrogen atom in grade ten
chemistry since it has properties of both metals and non–metals but today we
are going to go deeper into the 'simplest' little atom. Hydrogen is a
diatomic gas and when it is heated it will glow (aka release light). It does not
however come from blackbody radiation; it comes in red, blue/green and
purple wavelengths. Hydrogen is made of one proton and one electron and the
electron orbits the nucleus simply due to the attraction between the positive
proton and the negative electron.
This is when the classical physicists strayed from the facts; they said that the electron is in a continual state of
changing directions and this allows for the light to be emitted. The problem is
that this means that the electron is always losing energy – actually losing all
its energy, falling from its orbit until it is on top of the proton (this would
effectively kill the atom). Of course we know this is
wrong. Another scientist that was already mentioned in a previous post is Niels
Bohr. Bohr came up with the factual explanation – he came up with the idea that
the electron must orbit the proton at specific orbits which enables a
specific radius and energy. Bohr then came up with the idea that actually saved
countless hydrogen atoms (not really but he did prevent us from believing that
hydrogen atoms lasted only a fragment of a second). The idea is that when the
electron stays in one of its specified orbits it cannot release energy (produce
light) – his explanation produced the calculations for the wavelengths of the
colours described above for the Hydrogen atom.
Now, we discussed this before (in a previous post) but let’s
reiterate. Bohr explains that electrons will produce light if they are able to
fall from greater orbits. We said that this produces a photon with the energy
that is lost when the electron falls. * This goes along with the idea of conservation
of energy since the energy is never really lost just transferred to a photon.
Photons can then be used as energy
sources to allow for the electrons of other atoms to jump to greater orbitals; all the photon has to do is strike the atom and bam the electron is propelled to a greater orbit –
this is what is labelled a quantum jump.
Generally Speaking:
Classical:
- Predictable, using math and logic to solve problems. The extrapolation of something small to something on a larger scale.
- Matter makes up the universe – matter is made of particles
- Perception is limited to what a person can hear, see, smell, touch, taste – if it doesn’t fit into one of these categories it is irrelevant or simply fictional
Quantum:
- Energy is the basis of everything – even us!
- Only energy is key - matter is simply energy
- There are only possibilities and observations; when observed the possibilities dissipate and the observation becomes the reality (or more simply put observation is necessary for there to be reality)
- Electron orbits represent the location of electrons relative to a nucleus, there is no set path or pattern for electron movement
- Electrons can be in more than one place at a given time
Websites Consulted:
http://www.micromountain.com/assets/newhanim3.gif
http://resourcefullife.net/newtonian-vs-quantum-mechanics-perspectives/
