Talk:Quantum mechanics

Please do not put new stuff here. Most readers will jump right away to the bottom where the new stuff is supposed to go.

A mess

This article is a mess right now...I think it is best to approach this from a historical perspective, and work through step by step all the reasoning that was done in quantum mechanics. It is probably not a good idea to introduce advanced concepts in the article until much later. --HappyCamper 06:25, 3 January 2006 (UTC)

Holding off on the advanced concepts dilutes the very idea of quantum mechanics - to not include it on the basis of simplicity is solely an exercise in reducing the information available - you may as well just not iclude the information in the first place rather than try to simplify it further than it should realistically go.

I agree that the article is a mess. I agree that the history needs to be expanded, and all the ideas should be tied to that section, and explained more in later sections. A brief summary at the beginning is necessary, however.

If it can't be explained in Simple English, don't include it at all. Looking over the "Example," even I don't know what to do with that. This is where you have to acknowledge that there are some things that just can not be explained in any simple way without a higher education. You have to point that out to the reader and let them accept their own current limitations.

I agree, this article is a mess. For example: The phrase "Infrared photons are sometimes called 'black light'" is completely wrong, Ultraviolet light is referred to as Black light. --Quantumhorse

Merge notice

Kville105125 02:41, 14 October 2007 (UTC) Merged content from Quantum physics. See its old talk page Talk:Quantum physics

"Quantum Mechanics" section

How come there's a section titled "Quantum Mechanics" when the whole article is titled that? Also, shouldn't it be at the top anyways instead of under the "Uses" section, which is just a list? — Preceding unsigned comment added by 66.8.242.148 (talk • contribs)

"Quantum"

I believe "quantum" actually means "smallest" or "tiny" in Latin. It's been quite a few years since I studied the language, but I'm almost certain of this. 68.116.59.11 (talk) 09:05, 23 February 2009 (UTC)

• According to OED, quantum is post-classical Latin (4th century) and means “determination of quantity”. It is derived to be a second-declension neuter noun from the classical latin (most likely what you have studied) interrogative adverb Quantus which means “how much” or “how great”. 173.88.150.87 (talk) 02:34, 25 February 2009 (UTC)

quantum, suggestion for definition

in this context , means quantity. there were a few observed phenomena that were not consistent with the knowledge at the time these were resolved with the added assumption that energy can not come in any quantity, there is a minimal quantity, just like the smallest component of any material is an atom, (you cannot have half an atom of oxygen) so with energy there is an amount that can be transferred that you cannot halve. there was a problem with the theory that electrons go around in circles around the nucleus of an atom, they should have radiated some of their energy

Louis de Broglie had suggested that energy can only be emitted at a minimal quantity. so an electron would not continually transmit and lose energy furthermore he suggested that the electron could not be in any orbit, only in such orbits that would be the same length as could be composed of a wave of the same energy completing a whole number of cycle.

i'll fix this later. that's why this is in the talk page. 89.139.0.174 (talk) 09:31, 23 February 2009 (UTC)vish

Point by point.

one

The article says:

"Quantum mechanics says that a thing cannot move at just any speed."

Please supply a citation to support that assertion. Quantum mechanics says that energy only comes in multiples of a fundamental unit. The energy of a photon is linked to the frequency of a photon. Is that what the writer really had in mind? In the crude analogy that depicts an electron as a planet going around its sun, the nucleus, the radii of orbits are constrained by quantum conditions, so if there is assumed to be a velocity that supports orbiting at each distance from the nucleus, and the radii are constrained, then the linear velocities of electrons in orbits would be constrained as well. Is that what the writer had in mind?

As electrons move farther and farther from the nucleus (i.e., assume higher and higher orbits), their behavior more and more closely approximates the model offered by classical physics. So within the "classical limits" electrons are not limited in regard to their linear velocities.

Moreover, larger objects such as grains of sand, bullets, etc. operate under classical conditions. In short, many things can move at "just any speed."

Quantum mechanics developed out of questions such as why hydrogen does not radiate light so as to produce a continuous spectrum of light and instead radiates only four frequencies/colors in the visual range of humans. So I would prefer something like:

Quantum mechanics shows why things like neon lights have only certain colors and why things like x-rays can kill but things like heat lamps can only warm things up.

Patrick0Moran (talk) 01:33, 15 September 2009 (UTC)

74.9.199.154 (talk) 15:29, 16 May 2011 (UTC) The article is misleading: A heat lamp will certainly burn your skin if you get too close get too much exposure for too long.

The article clearly mentions "sunburn," which is not caused by heat. Patrick0Moran (talk) 22:09, 18 May 2011 (UTC)

two

The article says:

Isaac Newton thought that light was made of very small things that he called particles.

Newton did not use the word "particles." He said "corpuscles." How about "... that we would now call particles"? There is no need to write untruths in the cause of simplicity if there are no great barriers forcing us to do so.Patrick0Moran (talk) 17:02, 15 September 2009 (UTC)

Changed. Patrick0Moran (talk) 00:07, 18 September 2009 (UTC)

I'm sorry, but did you say "untruths"? Pastaguy12 (talk) 20:50, 7 November 2011 (UTC)

Right. It is not true that he called light "particles." Evidently some changes in conceptualization and/or language have made Newton's original language seem inappropriate to people today. To report that Newton called them "particles" is anachronistic. People will be able to deal with what he really said, especially if the article then gives the 21st century equivalent.Patrick0Moran (talk) 01:13, 8 November 2011 (UTC)

three

The article says:

People thought that a thing could not be both particles and waves.

This statement is wrong. People know that the sea is made up of particles such as atoms, molecules, and larger aggregations of matter, and that it also has waves. The statement should be:

People thought that a thing cannot be a particle and a wave at the same time.

Patrick0Moran (talk)

four

The article continues with a non sequiter:

Later, we began calling 'quanta' or 'photons', the 'packets' light travels in.

In outline, this paragraph says:

X says particles

Y says waves

And then out of the magician's hat comes "quanta," "photons," and "packets that light travels in." That sequence of ideas does not make sense. "Packets that light travels in" sounds, to me, like "packs that wolves travel in." It suggests that whatever photons are, they have to form some kind of flock to fly in.

The proper sequence should be:

X says particles

Y says waves

Z says wavicles, that is, something that is a little like a particle and a little like a wave.

Patrick0Moran (talk) 17:16, 15 September 2009 (UTC)

five

The article says:

The other ideas said that the electron would fall in because it would lose its energy to radiation.

"W loses X to Y" means, in general, that Y comes into action and wrests X from W. That is not what is going on when an electron goes to a lower energy level and emits a photon.

The other idea said that moving electrons lose energy because they throw off light. So when an electron goes around the nucleus, like a planet going around a sun, it would lose energy the same way, and then because it had lost the energy needed to keep itself away from the nucleus it would have to fall in to the nucleus. Since the electrons do not fall in to the nucleus, this idea must be wrong.

Patrick0Moran (talk) 17:26, 15 September 2009 (UTC)

six

The article says:

Electromagnetic waves such as light are another fact of nature that led to QM. In 1900, Max Planck thought for the first time that the energy of waves could be described as made of small packets or quanta.

So what was the "first fact"?

Why is the reader burdened with terminology like "electromagnetic waves"? First, the "electromagnetic" part of it is irrelevant at this point, besides involving vocabulary that is forbidding even to the average well-informed speaker of English. Second, the article has just thrown into strong doubt the appropriateness of talking about waves. Third, the statement is creating the inappropriate image of a wave, sort of like an ocean wave, that is composed of photons/packets/quanta instead of water molecules.

Planck began by trying to understand black-body radiation in terms of classical physics, so he was working with "electromagnetic waves" because that was how classical physics tried to do it. But to get from what Planck actually worked out to talking about things related to the foundation that has earlier been established in this article would take a great deal of careful explication.

The aim of the article at this point should be to introduce Planck's constant. Planck discovered that the only way to consistently explain the energy radiated by a heated object was to assume that any part of the energy that one might look at had to measure out as a multiple of some (basic quantity =) quantum of energy. Energy has to be measured like bricks, not like water.

Planck discovered that any energy measured had to be a multiple of some (basic quantity =) quantum of energy. Energy had to be measured like bricks, not like water. He did not like his own idea, but he was stuck with it.

Patrick0Moran (talk) 17:51, 15 September 2009 (UTC)

seven

The special case which relates the knowledge of position and momentum and puts a limit on the product of (what you get when you multiply together) those two values.

This collection of words is not a sentence. I can't guess what it is trying to say. Patrick0Moran (talk) 00:51, 18 September 2009 (UTC)

Target audience for this article is...

If the target audience for this article is to be highly educated people whose native language is something other than English, then it would probably make sense to take the English Wikipedia article on Quantum mechanics and just make sure that all low-frequency words are replaced or defined in simple English, and make sure that all of the sentence structures are dead simple. People who know the math quite well may only need to know the "definitions" for letters used for physical constants (there are several different meanings for e, for instance), but authors are generally inclined to assume that the reader went through the same series of textbooks they used), and do the same for variables.

On the other hand, for the average high school student from Afghanistan who does not have any good textbooks in his/her little school, and whose English is not adequate to technocratese, some of the math now used in the article may be expected to be beyond their abilities also.

There are some parts of QM that can be handled with nothing more than algebra, and it is not impossible to make the idea of matrices clear enough to show readers how there could be problems with multiplying matrix x by matrix y and getting answer matrix z, but multiplying matrix y by matrix x and not getting answer matrix z but some other matrix.

The equations that Heisenberg used to populate his matrices very definitely involved higher math, math that goes far beyond anything a physics major sees in the first year of physics. So that is the point at which one has to leave off the math in an article written for the general well-informed reader

The text that begins:

The particle in a 1-dimensional well

is for the person who is already highly advanced in math. It is unclear that s/he will know what a 1-dimensional well is.

Patrick0Moran (talk) 01:39, 18 September 2009 (UTC)

The target audience is very broad, and so the article needs to have a broad approach. A person with little maths or science should be able to understand the idea of quantum mechanics from the introductory paragraphs. The more advanced reader will be able to make sense of the equations. So far the article is looking good. Some of your examples and comments in the notes on this talk page would help explain the concepts in the article, be bold and add them to the page. Peterdownunder (talk) 02:00, 18 September 2009 (UTC)

Schrödinger

I hope that something helpful can be said about the Schrödinger wave equation. Unfortunately, none of the sources I have seen has a clear explanation. The minimum requirement would be to define what every letter (i.e., variable or constant) stands for, and what the units of each such term are. Patrick0Moran (talk) 21:55, 22 September 2009 (UTC)

A self-contradictory statement

The current version of the article says:

The ground state (state with the least energy) of the Quantum Simple Harmonic Oscillator is indeed in a minimum uncertainty state and behaves such that the inequality is an equality. In other words, that's when we can know the most about it, because we got to the limit of how much the universe will let us know.

It does not help anybody to say that an inequality is an equality. Isn't there some way to express whatever is intended by setting up a "limit as e approaches ground state", or something like that? Otherwise this is just mystification. Patrick0Moran (talk) 01:23, 26 September 2009 (UTC)

Getting too big

I'm getting warnings about the article going over 32k. Particularly for an article designed not to floor people with limited English reading ability, it would be better to keep things short.

I think that the basic math and concepts up through "elementary Heisenberg" can be handled in this article. The contributions that sprang up like mushrooms within weeks and months of his 1925 article had to use very heavy math. The people who can handle the math can probably handle adapted "senior" articles from the English Wikipedia if some care is taken to avoid unnecessary linguistic difficulties. If they can figure out what all the constants actually are (one of my gripes about many of these articles), then the math ought to carry them through -- assuming there is no waving of the magic wand or "left as an exercise for the student" jive.

I just tried to fix a misconception about Planck's constant that has marred the Intro to QM article on English Wikipedia for about 4 years -- and it was my fault. Doing so pulled a few threads in from later in the article, so I will have to make adjustments. I've already made a few. I also will have to move some of the stuff that comes at the reader too suddenly. It shouldn't be an intrusion between blocks of more introductory stuff. Also, the long section on matrix mechanics may be better in another article.

Is there any software around that would help with the vocabulary frequency issue? I would like to eliminate the lowest frequency items wherever possible and replace them with work-arounds. Patrick0Moran (talk) 07:32, 10 October 2009 (UTC)

Good work on the article. I see no problem have the article go beyond 32k (See Human). The warning just means some ancient browsers may not work. There some word frequency programs on the web. Also, I also found some neat readability scoring programs. --MarsRover (talk) 08:01, 6 November 2009 (UTC)

I tried the software. As far as native speakers of English go, it is already pretty good. For people who are technically competent, but in another language, I think one useful thing is to use as many graphics as possible. Infrared and ultraviolet take on immediate meaning on a labeled spectrum, for instance.

Could there be a simple English dictionary with definitions of words that may be necessary in some articles, but are not the kind of thing that will get its own article? That way instead of using a long circumlocution for "conversion" one could just put in a link to the simple English dictionary. Patrick0Moran (talk) 23:08, 8 November 2009 (UTC)

Conversion, but the simple dictionary definition does exist yet. --MarsRover (talk) 02:09, 11 November 2009 (UTC)

Are you suggesting that I follow the dead link to "conversion" and fill in something there? Patrick0Moran (talk) 16:14, 13 November 2009 (UTC)

There is a wiki readability calculator here [1] just type in the name of the article prefixed by simple, eg "simple:Quantum Mechanics". This will give you a rough guide to how the article is going. You will also find links to other calculators on my user page. In an answer to your question about linking to Simple Wikitionary - create a dead link and either write the definition yourself (recommended) or leave it for one of the wiktionary editors to write. --Peterdownunder (talk) 20:12, 13 November 2009 (UTC)

Or you could link to the definition for "convert" instead which does exist so it would work like this conversion Peterdownunder (talk) 20:17, 13 November 2009 (UTC)

format question

Does anyone know how to actually do a sidebar? I had to say something about natural units vs. the everyday kind of unit that develops because people use whatever is handy to measure thing, the first segment of the king's index finger, a grain of wheat, etc. It doesn't have a direct relationship to QM, but it is impossible to talk about why h is not "the smallest possible unit of energy," but is instead a proportionality constant such as one would use to convert from yards to meters.Patrick0Moran (talk) 21:40, 31 October 2009 (UTC)

How about this? --MarsRover (talk) 08:16, 6 November 2009 (UTC)

My Sidebar
Royal units
King's index finger = 2.5 inches
Other units
grain of wheat = 2 grams

Great! I knew I had seen something like that years ago. Patrick0Moran (talk) 15:33, 6 November 2009 (UTC)

How about a dictionary function?

For Chinese language sites there are several neat add-ons possible that make definitions for words pop up when there is a mouse event such as either a "fly over" or a "mouse down." I originally coded my own pop-ups, but later discovered some downloadable apps that users could easily apply to their own browsers. It would be really great if we could offer users such a utility for delivering explanatons of words such as "frequency" in simple English.

Without such a simple device users are going to be confronted with either no explanations or explanations that require them to navigate away from this page.

Erik Peterson has one utility that works in this way. There are add-ones for Firefox too. Patrick0Moran (talk) 02:28, 5 March 2010 (UTC)

source of confusion

The text currently says: "where R is the Rydberg constant, equal to 0.0110 nm−1, and n must be greater than m."

That's very confusing because n and m are integer variables, but nm stands for nanometer, no?

It would be better to copy the more exact value from the English Wikipedia article on the Rydberg constant and write out "meter" for m. Patrick0Moran (talk) 05:11, 7 March 2010 (UTC)

Moved from inappropriate spot

I'd like to see a better, simpler and more concentrated definition of QM at the start of the article, something like what 64.22.40.102 suggests below (while it seems good, I don't know a thing about this topic, so I have no idea if what he suggests is accurate). The way I see it, it is fine if the article gets more complex later on, it allows the reader to get more immersed and learn as he reads more. 85.252.183.30 (talk) 22:45, 17 August 2012 (UTC)

i dont understand this article? there are many big words — Preceding unsigned comment added by 84.57.245.109 (talk • contribs)

• Welcome to quantum theory. It doesn't get any simpler.— This unsigned comment was added by 61.218.55.27 (talk • changes).

I don't know if it was paradoxical, but the purpose of this wiki is intended to SIMPLIFY the language and concepts. -OneTopJob6

It's really difficult to do so without watering down everything...quantum mechanics is usually taught at the university level, perhaps even in 2nd or 3rd year. I know of one textbook which introduces the concepts at a grade 7 level, but even then, it assumes that the students are very advanced educationally speaking. --HappyCamper 06:16, 3 January 2006 (UTC)

A little bit of watering down (and then building up later) might be a good idea. I'd love to work on the whole article, but I'd want to change almost everything and I don't want to do that without discussing things before hand (for fear of ruining the hard work that has already gone into this). To give an example, take the introductory paragraph.

was: Quantum mechanics ("QM") is the part of physics that explains how the electron and other subatomic particles behave. QM also explains how electromagnetic waves such as light behave. QM is a mathematical framework for much of modern physics and chemistry, and helps us understand the smallest things in nature.

I propose: Quantum mechanics ("QM") is the part of physics that tells us how things that make up atoms work. QM also tells us how electromagnetic waves like light work. QM is a mathematical framework (rules written in math) for much of modern physics and chemistry, and helps us make sense of the smallest things in nature.

64.22.40.102 (talk) 15:42, 23 February 2009 (UTC)

Sandbox

I've created a sandbox for this article here. The article is fine, but I want to reorganize and simplify just a little. StevenJ81 (talk) 18:30, 4 April 2013 (UTC)

Heisenberg Uncertainty Principle

The effect described in this section of the article is actually the Observer Effect.

Please sign your postings.

I think it is important to keep a discussion of the difference between indeterminacy and observer effect clear. That being said, it has to be done in a simple and straightforward way so that the beginning reader will not get confused. There is no need to "mystify" things.Patrick0Moran (talk) 20:11, 1 June 2014 (UTC)

Leaps to conclusions without adequate explanation

The section on wavelengths and frequencies jumps to the statement “If the color of the light is infrared (lower in frequency than red light), each photon can heat up what it hits.” without explaining why this is the case at all. The proceeding lines don’t add context, either. Perhaps it should be moved to a separate paragraph with more explanation.