Quantum Mechanics?

Question

Explain Quantum Mechanics in a clear precise paragraph or two the delves into most aspects of it. Appericiate it.

Answer 1

Quantum Mechanics is a special branch of physics that studies the behavior of subatomic particles and their interactions... at the first glance that is. However it is much more as it 'delves' with most fundamental question of make up mater as we know it and the microscopic aspects its makeup.

To be certain
I'm not sure of my knowledge by explaining this to you however and by saying nothing the certainty of my knowledge is very high ;-)

Answer 2

Quantum mechanics is a theory of how nature works in the atomic and subatomic realm. Although it is a very weird theory (as I will attempt to show below) it is nonetheless the most rigorously verified theory in all of science!
(Which just confirms that this universe in which we find ourselves is a very weird place)

Perhaps the most central aspect of the theory is the so-called "wave-particle duality". Prior to the quantum theory, physicists were accustomed to thinking of things as being either a particle or a wave. Light, for example, was demonstrated experimentally to be a wave. Electrons, on the other hand, were considered to be particles.

According to the quantum theory, however, it was understood that light and electrons (and in fact, everything) have BOTH particle and wave aspects. For example, when it is not being "measured" in an experiment an electron is a wave ( a very bizarre kind of wave, a wave of probability) spread out over space. But when it is "measured" , the electron is a particle and somehow is made to 'choose' some particular place to be at. [There is no way of predicting with certainty where the electron will 'choose' to be found. The best one can do is calculate the probability of finding the electron somewhere (the probability wave, or "wave function" allows you to do this). ] This is sometimes referred to as "the collapse of the wave function".

One more aspect of the theory that I personally find intriguing is the "nonlocality" of the wave function:
You can arrange experimentally to have two distinct particles "entangled" in the same wave function (I'll spare the details). Let's call these particles A and B. You can also arrange to have these two particles go flying apart in opposite directions. You can then wait until the two particles are arbitrarily far apart, and then make a measurement on one of them, say A . This causes the "entangled" wave function to collapse, and forces BOTH A and B to 'choose'. Furthermore, since A and B had been entangled in the same wave function, their choices are not independent of each other! That is, if A makes a certain choice, then B is forced to make some other particular choice (in order that the system's energy, momentum, angular momentum etc be conserved).

But if A and B were so far apart that no signal could possibly have told B that A had chosen or what choice it had made, then how could B possibly 'know' and thus realize that it must also 'choose' and how it must choose?
[Recall that according to relativity, nothing can go faster than the speed of light]

Such experiments have actually been performed and, amazingly, it is found that B does indeed 'know' that A chose and thus knows what choice it must make, despite the fact that no signal could possibly have been sent from A. THAT IS VERY VERY WEIRD! Yet it is an experimental fact.
Somehow, B's knowing about A's choice has nothing to do with signals going from A to B at all. Both A and B had been "entangled" in the same wave function..a wave function is everywhere at once ("nonlocality") and when it collapses, it does so everywhere at once! In some mysterious and as-yet not understood way, relativity doesn't seem to apply in the collapse of a wave function. The wave function is just "one" (despite the fact that it may be spread out over a huge distance) and no signals are needed or observed.

Answer 3

Quantum mechanics quantifies energy on atomic and subatomic scales and attempts to define the nature of basic particles and phenomena where Newtonian theory fails to describe it. For instance, according to Newtonian theory, the electron would eventually collide with the nucleus. Since this does not happen, another theory is needed to describe how particles such as electrons behave in the most basic of physical systems.

There are several major ideas that distinguish quantum mechanics from classical mechanics. First of all is the concept of quantization. Energy isn't continuously distributed on small scales, but rather quantized according to individual atomic states and energy levels. These quantum states are each defined by a mathematical wave, a wavefunction. Secondly, measurements on the quantum level are limited to a lower bound and cannot be determined precisely. Simply put, one cannot determine both the position and momentum (or time and energy) of a particle at any given point in time but can only be accurate in one and not the other. The third major deviation is the concept of wave-particle duality, where the distinguishing factor between particles and waves are not clear, and may act like both under different conditions.

On larger scales however, these quantum effects are not noticeable and can be described by ordinary classical mechanics (or in the case of relativistic velocities, the special/general theory of relativity).

Answer 4

Quantum Mechanics is the theory of elementary particles from atoms to quarks. When you works with very small objects you are incapable of measuring the mechanical properties with accuracy, so the quantum formalism tells you that you are not supposed to obtain the same number every time you perform a measurement, instead you have certain probabilities of obtaining mean values of the physical observables. This is accomplish by replacing the physical scalar quantities with an operator observable, this operator must be hermitian to ensure the mean value to be real.

This seemingly lack of determinacy unleash some very interesting situations, such as the impossibility of measuring position and momentum at the same time, thus disappearing the concept of path in the space-time as well as in the phase space; and on the other hand the uncertainity principle which tells you that the more accurate you have a physical quantity measured the less accurate you 'll have measured the conjugate quantity (again position and velocity).

There are some other matters but they are rather complicated and deeper in physical knowledge, so I expect this overview to help you

Answer 5

Quantum Mechanics is the theoretical machinery that governs the universe on every scale from sub-atomic to galactic to the universe itself. But while Quantum Mechanics is always true, it is often no more useful than trying to measure the volume of an ocean with a teaspoon. It is on the molecular scale and smaller that Nature can be described precisely ONLY with Quantum Mechanics rather than the approximation of Newtonian Mechanics.

The three essential ideas of Quantum Mechanics are:
1) Particles sometimes behave like waves and waves sometimes behave like particles,
2) Energy and matter are ruled by uncertainty and probability,
3) Energy must be divided and added in integral -- rather than fractional -- amounts.

Answer 6

Quantum mechanics is a field of theoretical physics that explores the interactions of sub-atomic particles and their interactions. From quantum mechanics we can find out how many devices we have today work, such as computers, electronics, etc.

Such inventions as the electron microscope and the tunneling microscope are possible due to quantum mechanics. Though when dealing with quantum mechanics there are many strange things that happen but have been proven to be actually true. Quantum tunneling is one of them, where under certain conditions an object can pass through another solid object, etc. For more info check out wikipedia, they've got lots of material dealing with quantum mechanics, how it came about, etc.

Answer 7

Is this a joke?