Talk:Physics/Archive 7

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QUestion

There is an equation that basically goes like: (normally it is solved for s (distance))

a=2s/t*2

acceleration = (2 times distance) over (time squared)

My question is, in short, where does the 2 come from??? I thought acceleration = velocity / time -is this correct? and if that's correct then a = s/t*2 but where does the 2s come from? BriEnBest 07:39, 13 November 2007 (UTC)

This parabola-shaped lava flow illustrates Galileo's law of falling bodies as well as blackbody radiation -- you can tell the temperature from the color of the blackbody.

BriEnBest, see derivative and its inverse operation, the integral. Acceleration is the derivative of velocity; integrating, velocity is the integral of acceleration. That is where the 2 comes from. If s=t*t, then v=2t. In 1638, Galileo gave us his law of falling bodies, which is a square law. That is the reason that the lava in the image is following a parabola.

If we expand the laws of motion which the lava is obeying, we get other beautiful trajectories which are conic sections, as the answers.

--Ancheta Wis 11:49, 13 November 2007 (UTC)

oh yeah, i forgot.. that's an awesome picture btw. thanks :p 67.131.226.195 11:32, 13 November 2007 (UTC)

Good answer, AW (and cool picture!), but remember this page is only for discussing the article. Gnixon (talk) 05:27, 8 January 2008 (UTC)

Where is the section on teaching physics?

After ten years, doesn't Wikipedia have an article on the teaching of physics, i.e. physics education?

Well, this should be embarassing for the Wikipedia editors. Apparently there is an article on physics education...but the people who wrote it acted as if it had nothing to do with physics! They never came here to collaborate with the physics article editors. Seems a bit odd. And the people who spend time writing about physics, or its various fields, never thought about how to educate people on the subject? Well, I have made a few links that hopefully will correct this.

It is six years going on seven. Wikipedia started Jan 15, 2001. There was a physics article from the beginning.

One might argue that there also ought to be an article on learning physics, which is currently being addressed by the list of basic physics topics and category:fundamental physics concepts, where the goal in the encyclopedia was self-education.

Welcome to wikipedia. Your new perspective will be invaluable and the editors look forward to your additional contributions. You are welcome to get a username, which is handy if you want to upload images, for example.

I personally am a big fan of Louis Bloomfield, How everything works: making physics out of the ordinary ISBN 0-471-74817-X and also Paul G. Hewitt, Conceptual physics ISBN 0-321-05160-2. These books stay pretty much in the classical realm, but the physicists like Brian Greene, Alan Guth, Michio Kushi, Stephen Hawking, etc. have made widely-known efforts to reach the public with the post-Newtonian parts of physics. I wonder if you have thoughts on teaching about the classical realm in the high schools; that way the observations can stay inexpensive.

--Ancheta Wis (talk) 20:58, 17 November 2007 (UTC)

I just had a look at the PER article and was surprised to see that D'Alembert's principle was not mentioned in the section on Newtonian physics. If we look at things from D'Alembert's pov then we look for the forces necessary to reduce everything to statics. This idea works in electromagnetics as well (reduce everything to electrostatics). I learned this trick from Kurt Lehovec, one of the inventors of the integrated circuit; that's how he analyzed the non-volatile RAM in class for us, before there were any; now you can buy them in the drugstore). And if there aren't any forces to make it static, add in a fictitious force to balance it out.

--Ancheta Wis (talk) 23:03, 17 November 2007 (UTC)

I notice that the article section header is Physics education. That is actually of larger scope than Teaching Physics. Do you really mean Education? That could be interpreted as broadly as being the Presidential Science Advisor, currently staffed by a physicist, which raises issues which are currently not addressed in the article. Max Born stated that the physics of the current time will be the philosophy of the future (hence the politics of the farther future). I suggest that the section header be renamed Teaching Physics to skirt the change of scope in the section. --Ancheta Wis (talk) 00:27, 18 November 2007 (UTC)

After having listed some YouTube links to selected physics topics, I am undecided about Applied physics from the article. For example, the atomic bomb is an application which was developed immediately after the discovery of fission at the eve of WWII. But the amazing machines we are using to communicate with each other right now are examples which are just as good. Might an applied section be good to have links for?

I have tried to include links to demonstrate that physics is fun, vital and interesting. --Ancheta Wis (talk) 12:40, 21 November 2007 (UTC)

Learning physics

Since an (anonymous) editor has noted the omission of teaching physics, I propose a companion section on learning physics. Here, for example, one might note the need for some fundamentals which are necessary to get started, such as building up a store of physics experiences. These would be needed to supplement the laws of motion, etc. One thing might be videos of common phenomena, such as birds flying, balls moving, water dropping, cars starting and stopping, lightning, rain. The use of physics engines for video animation might be an ambitious project, but it would be useful for animating the motion of an airplane, ball, etc. Simple electrical circuits might be appropriate here.

I have moved the links to Talk:List of basic physics topics, that they might be integrated more fully into List of basic physics topics. --Ancheta Wis (talk) 17:54, 23 November 2007 (UTC)

http://en.wikiversity.org/

ThisMunkey (talk) 14:39, 3 March 2008 (UTC)

disambig?

I seriosuly doubt anyone going to the physics page is looking for the aristotile work1 —Preceding unsigned comment added by 99.247.120.178 (talk) 06:42, 26 December 2007 (UTC)

Here's the problem though. There is no other way that people searching for "Physics" by typing in the URL are going to get to the Aristotle work. Since Aristotle is pretty notable, and the Physics is a pretty notable work, I suggest leaving the disambig. SaveThePoint (talk) 06:45, 26 December 2007 (UTC)

I think you both have good points. Couldn't someone looking for the work by Aristotle find it easily enough from the Aristotle article or by searching for "Physics Aristotle"? Gnixon (talk) 05:22, 8 January 2008 (UTC)

What the Wikipedia guidelines have to say about it? Redundance is not necessarily bad, specially in an information network. My personal impression is that keeping the disambig is a harmless choice. Old Palimpsest (talk) 19:12, 22 February 2008 (UTC)

Image:Meissner effect.jpg listed for deletion

An image or media file that you uploaded or altered, Image:Meissner effect.jpg, has been listed at Wikipedia:Images and media for deletion. Please see the discussion to see why this is (you may have to search for the title of the image to find its entry), if you are interested in it not being deleted. Thank you. Papa November (talk) 15:31, 28 January 2008 (UTC)

Definition

The words 'how the natural world works' in the first paragraph suggest too strongly to me that the natural world must have a set of rules or mechanisms. I believe that this is is too restrictive. It also appears to be a misquotation from the given source.Martin Hogbin (talk) 23:38, 4 February 2008 (UTC)

I have reverted back to Krea's formulation. --Ancheta Wis (talk) 23:56, 4 February 2008 (UTC)

Personally, I prefer that formulation. 'Behaves' seems a good word to use.Martin Hogbin (talk) 09:15, 5 February 2008 (UTC)

"Branches" of Physics

I suggest a reformulation of

Although seen as distinct today, natural philosophy, chemistry, mathematics and biology are all "branches" of physics.

Mathematics is a tool, not a "branch" of Physics, and must definitively be excluded of the list. Physics assumes that natural processes are intelligible through mathematical models. It is therefore unable to found mathematics in the same sense it apparently founds chemistry and biology. Old Palimpsest (talk) 15:16, 22 February 2008 (UTC)

Removed the problem sentence. 'Twas "physics snobbism" at work :-) and unsourced. Vsmith (talk) 15:54, 22 February 2008 (UTC)

Thank you very much for your attention. Concerning snobism, I don't think it is too snobish to mention the indisputable fact that quantum mechanics explains the Periodic Table of chemical elements in every detail. In this sense, it is perfectly legitimate to consider chemistry as a branch of physics. Old Palimpsest (talk) 18:51, 22 February 2008 (UTC)

Quantum Mechanics - Picture or Illustration

The picture on the quantum mechanics section was very convincing but after a thought, not very convincing at all (as improbable). Could some one add the words "representation" or "image of" and if "image of" include what sort the "imager" was?
Would anyone help me>? What is the name for physics relating to the force of a bullet at high speed compared to a bullet at low speed. IE: a bullet at low speed will push an object but a shot bullet (at high speed) will pierce the same object. What section (or name) is that?
ThisMunkey (talk) 14:37, 3 March 2008 (UTC)

The hydrogen atom illustration shows the calculated probability density of electron orbitals in hydrogen (see Hydrogen atom#Visualizing the hydrogen electron orbitals). Electron orbitals cannot really be imaged, since when you measure an electron position it can only end up being in one place at a time.

As for bullets, you might be interested in ballistics and physics of firearms. — Laura Scudder ☎ 14:58, 3 March 2008 (UTC)

I have seen pistures of quarks where the electron was smashed in an accelerator and the little sparks where seen as evidence of quarks. Maybe it should be noted as an illustration. No, the physics of firearms doesnt make a reference to what Im after. Maybe its some sort of friction but the physics of the impact changes at high speed. Maybe its not researched ? Unlikely.
ThisMunkey (talk) 10:20, 4 March 2008 (UTC)

The same goes for a hammer.
ThisMunkey (talk) 10:22, 4 March 2008 (UTC)

The main issue is: Momentum. I think the picture is fine. Missingdata1 (talk) 18:44, 23 May 2008 (UTC)

Heavy picture

http://en.wikipedia.org/wiki/Image:CMS_Yep2_descent.gif that is shown under http://en.wikipedia.org/wiki/Physics#High_energy.2Fparticle_physics is a very heavy picture (nearly 4MB) and not really that much important. Isn't it better to change it to a non-animated picture of the particle accelerator instead? --81.227.87.148 (talk) 18:16, 9 March 2008 (UTC)

Agreed, it was far too large for the article, and it was forced to be 300px wide as well, so any user preference would be overridden. I have replaced it with an appropriate small still of an LHC simulation. SFC9394 (talk) 19:13, 9 March 2008 (UTC)

Definition

Perhaps the best definition of physics is the all-encompassing and simple, yet abstract, definition: "Physics, the most fundamental physical science, describes the basic principles of the universe." (Serway) --Kasparov (talk) 22:51, 13 March 2008 (UTC)

core theories

i think we should revert to putting a hedding for core theories of physics as branches of physics, be cause thats what they are. Calling thermodynamics, quantum mechanics, etc core theories is incorrect since each of them consists of mnay theories and it just sounds like a bad high school paper. Brnaches of physics is what are the various theories of sections of physics not fields that use more then one if not all the brnaches of physics. Anyways am just floating the ideas around to get some feedback. —Preceding unsigned comment added by 24.36.181.171 (talk) 08:05, 2 April 2008 (UTC)

I think the change from "core theories" to "branches of physics" lost some of the sense of what the article was saying. Each of the fields listed (classical mechanics, electromagnetism, relativity, thermodynamics, and quantum mechanics) is governed by a particular body of theory. There are multiple individual theories within each, but these fit into the overarching framework of theory that defines each field. "Branches of physics" on the other hand are things like nuclear physics, molecular physics, solid-state physics, etc. "Branches" are areas of research in which scientists work. Classical mechanics is not a "branch" of physics. Nobody is studying classical mechanics anymore. It is just something physicists use in doing their work. Similarly, there is little fundamental research going on in electromagnetism or thermodynamics. These are areas of physics that are defined by an essentially-complete body of theory. The areas that remain open are applications of the theories, and development of new bodies of theory (as relativity developed out of classical mechanics and electromagnetism).--Srleffler (talk) 04:41, 9 April 2008 (UTC)

Another way of putting it: classical mechanics, electromagnetism, relativity, thermodynamics, and quantum mechanics are bodies of theory that are used in nearly all branches of physics. They are core bodies of theory that underly pretty much everything else in physics. I understand the complaint that these are not single theories. Perhaps someone can come up with a better name than "core theory".--Srleffler (talk) 02:46, 10 April 2008 (UTC)

There is precedent for denoting them 'core theories': for example, the biophysicist and Howard Hughes Medical Investigator Charles F. Stevens, M.D., Ph.D., has written a condensed summary of The Six Core Theories of Modern Physics MIT Press ISBN 0-262-69188-4 (1995). In Stevens' view, the six core theories are classical mechanics, electromagnetism, quantum mechanics, statistical physics, special relativity, and quantum field theory. And in Stevens' sense, the branches of physics which are areas of current research in physics are denoted 'Modern Physics' just as Srleffler states. --Ancheta Wis (talk) 10:35, 10 April 2008 (UTC)

How about denoting them 'core frameworks'? That leaves room for the current theories in modern physics to roam unfettered, so to speak. --Ancheta Wis (talk) 02:19, 11 April 2008 (UTC)

am on agreement on the issue i reverted back to branches of physics from core theories but now am starting to see this isnt really appropriate either, but something better then core theories is in order i think —Preceding unsigned comment added by Tomasz Prochownik (talk • contribs) 20:51, 15 April 2008 (UTC)

i put fundamental branches of theory in physics, whats everyone think about this?Tomasz Prochownik (talk) 01:44, 21 April 2008 (UTC)

How about "Basic theories"? Gnixon (talk) 19:40, 28 May 2008 (UTC)

I'm concerned that "branches of physics" is a better description for the research fields than it is for mechanics, E&M, etc. Can we discuss this further? Gnixon (talk) 16:35, 4 June 2008 (UTC)

FWIW, I agree with Gnixon, Srleffer and Ancheta Wis: "Core theories" is best ("basic theories" sounds a bit...basic). PaddyLeahy (talk) 17:47, 4 June 2008 (UTC)

I could live with "core," but can you elaborate on the objection to "basic." (Not to make a mountain out of a molehill.) Gnixon (talk) 17:58, 4 June 2008 (UTC)

Well, basically, "basic" is basically alright but, you know, kind of not very specific, the basic trouble is it's a bit naff, :) maybe it's a specifically English naffness I dunno PaddyLeahy (talk) 19:21, 4 June 2008 (UTC)

Poor taste? Meh, "core" is fine with me. Gnixon (talk) 20:29, 4 June 2008 (UTC)

branches doesnt really confuse with fields in physics, since areas of research are called just that fields, what the title needs to adress is the theoretical division upon which physics rests or the divisions that exist between all the different theories, plus this page also lists a section of research fields in physics so i thinkn it provides some clarity.Tomasz Prochownik (talk) 02:25, 9 June 2008 (UTC)

Diagram: Speed/Size

The diagram is oversimplified. Quantum mechanics may be relativistic (Dirac equation). Field theory has also nonrelativistic formulation. Classical mechanics may be relativistic and non-relativistic. Therefore I would say it's false and misleading. 87.206.101.253 (talk) 19:16, 30 April 2008 (UTC)

According to the way we have it laid out, classical mechanics and relativistic mechanics are distinct. As for QFT, I was under the impression that QFT came out of the need to make QM relativistically covariant.--Loodog (talk) 19:29, 30 April 2008 (UTC)

Request for mediation at Shor's Algorithm

IBM implemented an alleged quantum computer which ran Shor's factoring algorithm to factor the number 15.

A user had been qualifying quantum computer with simulated quantum computer and qubits with psudo-qubits, etc. I reverted the edits, asking for citations. No reasonable citations were provided and such changes were made again.

I do not know much about NMR quantum computers so I must assume these changes were made in good faith. I am unable to reach an agreement with this user and do not know how to proceed. If anyone knows anything about NMR or wikipedia policy, your assistance would be appreciated. Please see: [1]. Thanks Skippydo (talk) 21:23, 28 May 2008 (UTC)

Skippydo, it's basic quantum mechanics: the simplest case (up or down) (1 or 0) is a mixture of multiple states (1 or 0) at the same time. And it will take an observation to pull out the answer (how much 1 vs how much 0). When a quantum computer is realized (and it already is, because theory says we live in a QM world), the work will be to build devices which pull out the answer.

Don't be buffaloed by the NMR. It is just a technology for getting known states (spin up or spin down). A quantum computer calculates everything all at once, and it will take work to disentangle the results of a quantum computation so that they can be read out like a traditional sequential computer. This point of view comes from R. P. Feynman ===> A quantum mechanical calculation is the same as an observation. --Ancheta Wis (talk) 02:58, 29 May 2008 (UTC)

This discussion should continue at Shor's Algorithm, not here. 128.112.84.21 (talk) 14:16, 29 May 2008 (UTC)

hi>>>>>>>>>

you suck men!!!!!!! —Preceding unsigned comment added by 124.217.107.209 (talk) 11:07, 19 June 2008 (UTC)

lock?

when did this page become locked and what were the reasons for this? Tomasz Prochownik (talk) 07:17, 20 June 2008 (UTC)

See these edits. Gnixon (talk) 11:29, 20 June 2008 (UTC)

any idea when it will be lifted? Tomasz Prochownik (talk) 15:26, 20 June 2008 (UTC)

experimentation in physics

can somehow explain to me the whole thing about experimental physics begining in the middle ages. What credible sources say that. The author of this edit, jagged 85, naturally, uses info thats totally distorted and looks like its gonna force me to have to upload my sections on his shaddy scholarship even quicker. When experiment was introduced is matter of debate, since for example would not have archimedes had to have used experiments to discover the principle of bouyancy and ideas around levers. The link also lead to a section that contains this

"Another medieval Muslim physicist who contributed towards experimental physics was Abū Rayhān al-Bīrūnī (973-1048), who developed the earliest experimental method for mechanics. Al-Biruni and Al-Khazini (fl. 1115-1130) also unified statics and dynamics into the science of mechanics, and combined hydrostatics with dynamics to create the field of hydrodynamics."

the quote used to back this up is this

"Using a whole body of mathematical methods (not only those inherited from the antique theory of ratios and infinitesimal techniques, but also the methods of the contemporary algebra and fine calculation techniques), Arabic scientists raised statics to a new, higher level. The classical results of Archimedes in the theory of the centre of gravity were generalized and applied to three-dimensional bodies, the theory of ponderable lever was founded and the 'science of gravity' was created and later further developed in medieval Europe. The phenomena of statics were studied by using the dynamic apporach so that two trends - statics and dynamics - turned out to be inter-related withina single science, mechanics. The combination of the dynamic apporach with Archimedean hydrostatics gave birth to a direction in science which may be called medieval hydrodynamics. [...] Numerous fine experimental methods were developed for determining the specific weight, which were based, in particular, on the theory of balances and weighing. The classical works of al-Biruni and al-Khazini can by right be considered as the beginning of the application of experimental methods in medieval science.

where does it say that experiment was introduced into physics or statics or dynamics for that matter. All it mentions at the end is that early experimentation was used in science in general and not physics, and pretty much everything listed in that little sentence is totally taken out of context, which am going to be demonstrating very soon cause i actaully decided to read that book myself.

in order to make bold statements like this is gonna require respectable sources on the topic not loose interpretations which do not deal with the matter specifically. All this book deals with is science in the middle ages in the islamic world. It does not deal with the general history of physics, and not to mention it doesnt say what the author is claiming. Jagged were does it say in that book that experimentation was introduced into physics,list the quotes here, and the ones made for statics and dynamics as well. It doesnt make those statements you just decided to make your own interpretations and post it here.

list the quotes from that book here on the page were it says what you claim. By the way just for the other users of this page, the book he quotes is available fully on google scholar, i recommend that others read it and see if it says what jagged claims.

Tomasz Prochownik (talk) 06:41, 20 June 2008 (UTC)

This occurred during the time when physics was natural philosophy. The segmentation and professionalization of science occurred 200 years ago, but that does not mean that physics did not exist before that. See, for example, W.F. Bynum & Roy Porter (2005), Oxford Dictionary of Scientific Quotations ISBN 0-19-858409-1. Quotation (Al-Biruni 7#3) shows that he ran experiments. He correlates the rapid speed of a mountain river with the size of the huge stones which it carries, and compares that to the size of the tiny particles of sand "near the sea where the streams flow more slowly". He thought about the ramifications of his hypothesis: "... if you consider all this you could scarcely help thinking that India has once been a sea which by degrees has been filled up by the alluvium of the streams."—source: Alberuni's India, translated by E.C. Sachau (1888) I, 198. Al-Biruni (973-c.1050) is thinking like a physicist. What more do you want? --Ancheta Wis (talk) 10:55, 20 June 2008 (UTC)

Ancheta, I'm not sure if you're following his point. Tomasz seems to be objecting to "experimental physics began in the middle ages." He may be correct that the source doesn't back that up---the source may be saying that Biruni and Khazini were the first medieval scientists to rely on experimentation, not that they were the first scientists ever to rely on experimentation. Gnixon (talk) 11:38, 20 June 2008 (UTC)

I have absolutely no idea about what ancheta is talking about. What am objecting to is that the whole idea of experiment is of philisophical in nature and there is no clear consensus when it emerged and what it consititues, and is matter of debate among philosophers of physics to this day, and how it can be refined along with the scientific method. Secondly, the quotation that is used doesnt support the claim being made. Lastly, in order to make such bold claims requires several respectable sources on the topic not a book islamic science. Tomasz Prochownik (talk) 15:25, 20 June 2008 (UTC)

It would be very useful to have some standard reference on the history of physics to guide us. I don't know of one off-hand. Gnixon (talk) 15:55, 20 June 2008 (UTC)

Development article

The last substantive edits to Talk:Physics/wip/development_article were made 9 months ago. If we've addressed its raison d'etre, is it time to delete it? Gnixon (talk) 16:06, 20 June 2008 (UTC)

i think in the development article there needs to be section on the branches of physics that exists in the orignial page because it is important to illustrate the theoretical division in physics and how it relates to other field. Plus it is these theoretical branches of physics that make research fields such as engineering, optics, nuclear physics, solid state physics etc possible. Tomasz Prochownik (talk) 02:19, 21 June 2008 (UTC)

The question is whether it's still useful to have a development article, or whether the main article is sufficiently stable to be edited directly from now on. Gnixon (talk) 04:00, 21 June 2008 (UTC)

am of the opinion that the original physics page is really good, although it could use some work, like the missing references. The development article looks sloppy; but does have some good sections, which of course can incorporated into the orignal physics pageTomasz Prochownik (talk) 05:59, 21 June 2008 (UTC)