What does quantum physics explain?

Question

I want to see if anyone knows the anwser to this question.

Answer 1

QP is able to predict events at the subatomic scale of things. delx delp > h is the so-called Heisenberg uncertainty principle, which says we cannot measure the location (x) and momentum (p) of a particle concurrently. There will always be some uncertainty (h or greater) of one or the other. The "dels" are a measure of uncertainty.

h is the Plank's constant, which shows up all over the place in QP. For example E = hf; where E is the energy of a quantum (e.g., photon) and f is its frequency.

Where there is uncertainty (e.g., those dels), we will find a frequency distribution...a shape of possible values. The bell curve is such a shape for example.

Turns out that little bitty particles, like electrons, flit about at random (e.g., around a nucleus) and carve out a frequency distribution as to where they might be found. The peak of said distribution is where the probability of finding the particles is the highest.

So contrary to the sun and planets model for electrons around a nucleus, electrons bounce around the nucleus to carve out a three dimensional probability (frequency) distribution around the core. There is a sort-of cloud of electrons around an atom. That's QP at work...predicting where those clouds will be.

Another place where QP is at work is in telling us why light acts like both waves and particles. The answer is obvious, light is made up of bundles (quanta) of energy that travel in waves...like molecules of water travel in waves on top a pond. But it took until early last century for physicists to actually quantify the obvious through QP. In fact, Einstein won his Nobel not for relativity, but for his contribution to the photo-electric effect, which was one of the first indications of the quantum characteristic of light.

Also interesting, S. Hawking gained his fame for using QP to predict leakage out of black holes. Such leakage (stuff popping out of black holes instead of being sucked in) has since been observed. So this is a case of where QP was applied to macro events rather than micro, which is the normal domain for QP.

This is not surprising because a guy named DeBroqlie (pronounced De Broy) has modeled the wave nature of all matter...large and small. In which case, all matter has some level of uncertainty in location and momentum. The thing is, though, the delx and delp for big things are so very very tiny that we don't normally see them. [See source.]

PS: Contrary to one answer, QP has not explained gravity. In fact, its inability to explain this fourth of the four fundamental forces of nature is one reason physicists have turned to string theory...it does predict gravity and the messenger particle, the graviton.

Answer 2

Its replaces classical mechanics at the atomic and sub-atomic levels.

While Newtons equations explain the behavior of falling apples and planets very well, they cant explain squat when it comes to the behavior of individual sub-atomic particles, ie, electrons, photons, quarks, etc. So quantum mechanics evolved to explain the counter-intuitive behaviors that things on a very small scale have, like wave-particle duality, uncertainty, probability, etc.

So Quantum Mechanics is just the study of the physical behaviors of matter on an extremely small scale. see, its really not that intimidating! It just doesnt work anything like what you know, thats what makes it difficult.

Classical physics is the explanation of physical behaviors of matter on a large scale.

edit: and just as a side note, while it does seem like voodoo magic sometimes, QM is EXTREMELY accurate as to the particle behaviors, and its equations and theories have been tested over and over again and have held up every time.

another edit: NO! Quantum Mechanics does not touch Gravity with a 10 foot pole. General Relativity is used for the gravitational equations still. That is one of the fundamental and longest standing problems of QM, that the two sets of equations (QM and General Relativity) are actually contradictory on some levels. That, by the way, is why Einstein never bought into Quantum Mechanics. We're missing a big piece of the puzzle, but we dont really know what yet.

M-theory (a hybrid of all 5 of the string theories and 11D supergravity) is the best new candidate to unify gravity and the sub-atomic, and it is just beginning to incorporate gravity into the quantum world. It has impressive results so far mathematically, BUT testable hypothesis have been hard to come by yet. Plus the mathematics are so difficult its starting to require much more supercomputering, which alot of classical 'blackboard' type physicists shy away from...

Answer 3

And you do you the answer? Lol

Quantum physics is a branch of science that deals with discrete, indivisible units of energy called quanta as described by the Quantum Theory. There are five main ideas represented in Quantum Theory:

Energy is not continuous, but comes in small but discrete units.
The elementary particles behave both like particles and like waves.
The movement of these particles is inherently random.
It is physically impossible to know both the position and the momentum of a particle at the same time. The more precisely one is known, the less precise the measurement of the other is.
The atomic world is nothing like the world we live in.

Answer 4

The father of quantuim physics is Shroedinger. His complex equations define the spatial relationship between the electrons around the nucleus and the probability of where they would be in any one time. The classical orbital model of electrons orbiting the nucleus like small planets has been disproved. Quantum physics also defines the discrete amounts of energy needed to excite electrons enough that they change their energy levels.

Answer 5

I bet your textbook knows.

Quantum mechanics explains the behavior of things that are very small.

Look it up on wiki if you want a general overview.

Edit--it absolutely DOES describe nuclear phenomenon. It has been adapted to special relativity (field theory). It almost certainly does describe gravity (general relativity) as well, although the details of that are not completely worked out and agreed upon.

Answer 6

quantum physics describes how molecules, atoms, sub-atomic particles and electromagnetic radiation behave and interact with each other.

a much more interesting question is whether there is a theory that includes both quantum mechanics and relativity.

Answer 7

Everything - except gravity and the atomic nucleus.

Answer 8

Why I get a headache when I think about it.