Abandoned Forum

[Cherokee_girl]

Physics final by Cherokee_girl

Light: Particle or Wave?

What is light? Is it a wave, a particle? Both or neither? No one really knows, not even scientists. It's been proved as a both a wave and a particle, but what is it really? I think it's neither and both, but since I cannot come up with evidence to prove it's not, so I'll show it's both.

If light is a particle, then how can we explain the wave-like behavior it's exhibited? It bends around objects in it's path. Thomas Young, a British scientist in the 1800's, proved light was a wave in his double-slit experiment; it consisted of two closely spaced slots and a single light source, the sun. His experiment took what the world knew of particles and tested it. If the particle theory was to hold up, only two clear slots should have shown up; he observed many slits instead, suggesting that light was a wave not a particle. Waves bend around slits, called diffraction, and are viewed as many instead of two. In this same experiment he proved that individual colors have their own wavelengths. Young went on to show how it could be split into the different colors. Wave theories also explained interference and polarization that particle theories could not.

But if light is a wave how does one explain it's particle-like activities? Particle theory could explain reflection, reflection, and experiments in radiation. If light is made of particles, then it should work in straight lines. Take a shadow for instance; your shadow is formed by the blockage of light by your body. If light was a wave, it would travel around you, therefore not giving you a shadow. It doesn't though, showing it is a particle. Light particles are often described as being a photon or quantum. Photons were found by a German physicist, Max Planck, in the 1900's and are tiny packets of light energy that are unlike traditional particles; they do not have a defined volume in space. He had a problem that disproved part of the wave theory. That part predicted that small wavelengths should be accompanied by a large intensity; Planck proved that, in a black-body radiation experiment, wavelengths are small with the intensity and energy output also small. This, plus evidence from previous theories and experiments, told scientists that light was both a wave and a particle.

But the wave-particle duality theory. developed in 1924 by Louis de Broglie, says that light can travel in both wave- and particle-like ways. He said that photons have mass and travel along a wave. This combination of the wave and particle theories is generally accepted now as an explanation for how light travels. A true explanation depends on our experiment and its purpose. If you are looking for waves, that's what you'll get; if your looking for particles, you'll get particles instead. Wave-particle duality explains the many behaviors of light that fits into the wave theory, also into the particle theory, as well as vica versa.

So, what is light? It's not completely a wave and it's not totally a particle either. So what is it? I think it is both, as suggested by the wave-particle duality theory. It acts like both, so it has to be either both or neither in my mind. But that's just what I think. Light is a wave and a particle or neither.

[Bomadeno]

It might interest you to look at it at the other end of things as well - not only can light, traditionally seen as a wave, behave as a particle, so can particles behave as waves. For example electrons - particles in most peoples minds, when acccelerated sufficiently, can develop wave properties - they diffract, and the interfere, the queer little things.

These weird behaviours are governed by seemingly innocent formulae - innocent only to the unknowing eye.

hf = W+1/2mv^2

Why so weird? Look at the components on either side of the equation - on the left, a formula relating to waves - 'hf' and on the right a formula relating to particles - mv^2

So... what the formula gives you is waves=particles...

Luckily I'm revising physics for exams at the moment, tis great stuff.

Another often overlooked-because-its-so-popular is E=mc^2. That's similarly weird... enegy = mass... nice and weird that one too.

Coinicidentally, I picked both and neither - I think both is a good explanation for the time being, but I think there is a complex underlying theory, something that means our concept of waves and particles is wrong yet to be discovered. I'm not sure exatly what though. Maybe another day i'll realise. Maybe not

[trumpetprodigy]

If anyone wants, I can post the 5 page essay I wrote, though I doubt anyone would want to read it, and it's probably not accurate.

[Cherokee_girl]

Mine's probably not either, but I posted it anyway.

[Insanity test]

Perhaps everything we experience is of the same basic rules, but we merely observe them under different states and influences.

If energy = mass and a wave is essentially energy and light is both a wave and a partical and particals behave like waves under the correct conditions, then isn't everything we experience merely like to different bands of the electro-magnetic spectrum and everything belongs to one major catogry and we've just split everything up into little human sized bits?

For instance - particals which make up everythig we experience are with little energy. By using a partical accellerator we give them energy and they behave like waves.

Waves are merely particals or other forms of mass with great energy and we just can't sense this yet.

Or maybe Im just bonkers. Or maybe thats what you all meant anyway.

But seeing as we're on physics, there are three things which really get me thinking:
Eternity - or before the big bang and after everything
Quantum - how the hell can a partical jump to another place without covering the intervening space??
and Time - apparently time travells at different speeds at different points of the galaxy. And black holes swallow it.

Oh and a fourth - Infinite gravity and infinite compression: in other words, a singularity.