Hey all...

I was just breezing through some other threads when i realized that i needed to understand quantum mechanics better to fully comprehend a lot of them.

Could someone give me a good idea of what quantum mechanics really is all about?

Peace:cool:

It was found last century that light (a wave) occasionally behaved like it was a particle. When phycists started discovering other particles, like electrons, and fired them at diffraction gratings, they behaved like a wave does. That is they produced a definite diffraction pattern. This immediately led to a discussion of what is a particle and what is a wave. Long and short of, it led to the concept of wave-particle duality. The idea that these things where interchangeable.

The next trick was to then start building mathematical models describing what was going on. This was done by Erwin Schroedinger. He equated a 'wave function', a description of a wave in 3 dimensions, with the energy of a particle, it's mass and velocity. Gory details here (http://scienceworld.wolfram.com/physics/SchroedingerEquation.html). There are several forms of that equation you can use to solve for different cases. Which one you use depends on the circumstance.

A peculiar thing about the solutions of Schroedingers equation is that iit's solutions for Energy, amongst others, are discrete. That is, you can have 1E, 2E and 3E but not 1.1E or 2.4E. The same holds true for other particle properties such as momentum, spin and angular momentum. This was a wholly new view of the things. they called these discrete values Quanta, from the Greek for small, IMSC.

The study of Quantum Mechanics is the study of the world of particles and their quantum numbers.

As an aside. The question then arose, what was the meaning of this wave function? After a very large conference in Copenhagen with the founders of Quantum Mechanics they decided it described a probability function. In other words the wave describes the probability of a particle having a given quantum number in a system. This is the Copenhagen interpretation. It also the thing most people disagree with about Quantum Mechanics. FWIW, the theory has been described as the most successfull theory in Physics as it's past all experimental tests.

That's the basics. A bit more for you. As this is a wave we are describing you can take it's fourier transform. This leads to a startling result, products of certain quantities are greater than or equal to constants. Gory details here. (http://scienceworld.wolfram.com/physics/UncertaintyPrinciple.html) As we are dealing with probabilities it means that the more we know about one thing, the less you do about another. What's more, this in an inherent property of the particel and nothing to do with measuring equipment or accuracy of equiopment. It is Heisenberg's Uncertainly Principle.

Want to know more?

I've got the main idea, but where does Stephen Hawking come in to all of this?

How about Alan Guth? I've heard their names more times than i can count but i'm not quite sure what they did in the field of quantum mechanics.

Hi Stef730,

Stephen Hawking mostly did research on black holes. I am not familiar with his exact results, but probably the most famous theoretical construct proposed by Hawking is the "Hawking radiation" of black holes.

This is when a particle and antiparticle create from the vacuum and one of the two falls into the black hole before they can annihilate again (the energy for the particles is "borrowed" for a short while). When there is no particle to annihilate with, then the other particle is free to cruise into space. For an external observer, it would seem that the black hole emitted a particle, and has hence radiated it away. Hawking proposed that by this mechanism, black holes can evaporate and eventually dissappear (because the energy for the particles comes from the gravitational energy of the black hole).

I should add that this is more quantum field theory, a more extended version of quantum mechanics :)

Bye!

Crisp