Quantum mechanics....please explain?

Question

i have read 2 whole books on it but i dont get it. i kno its a theory that explains how electrons move and that one electron moves so fast thats it's like everywhere in its energy level at the same time... but please help me. i have a test monday

Answer 1

One of the key differences of quantum mechanics as compared to classical mechanics, is the probabilistic nature of the universe. A fundamental concept in the theory is the affect of measuring anything. We cannot measure something without changing it. Therefore, the property we are trying to measure always changes when we attempt to measure it.
For example, we can never know the exact postion of an electron in orbit and its momentum (mass, speed and direction) at that position. We can measure either one, the position or momentum, but never both. The 'act' of measuring itself will change these properties. Quantum mechanics, therefore takes a probabilistic approach to the universe. Going back to the example of an electron in orbit, with classical mechanics you would visualize this as a solid electron floating around its nucleus, almost like a moon orbiting a planet. Quantum mechanics takes a statisitical approach, since you can never know the exact position and momentum of an electron, you can't picture the electron orbit simply and exactly as classical mechanincs would. In quantum mechanics one would visualize the electron orbit as an electron density cloud. Quantum mechanics provides a probabilistic result rather than a deterministic result. Quantum mechanics can't tell you the exact position and momentum of the electron, but it gives you the probabilty of finding the electron at a given position. This is pictured by an electron density cloud. The denser the cloud is at a specific point, the more likely it is that the electron will be at this point. The theory is not really saying that the electron exists in all these places at once, but instead says here are all the possible places that the electron can be and gives the probability of the electron being at each given spot. This is a fundamental difference from the exact result we are used to getting from classical mechanics.

Answer 2

Quantum mechanics (or quantum theory) is a physical science dealing with the behaviour of matter and waves on the scale of atoms and subatomic particles. It also forms the basis for the contemporary understanding of how large objects such as stars and galaxies, and cosmological events such as the Big Bang, can be analyzed and explained. Its acceptance by the general physics community is due to its accurate prediction of the physical behaviour of systems, including systems where Newtonian mechanics fails. This difference between the success of classical and quantum mechanics is most often observed in systems at the atomic scale or smaller, or at very low or very high energies, or at extremely low temperatures. Quantum mechanics is the basis of modern developments in chemistry, molecular biology, and electronics, and the foundation for the technology that has transformed the world in the last sixty years.