Talk:Body relative direction

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brain
This article claims that teh left and right brain differ in functions. I read on Wikipedia once that this is a myth. Juan Ponderas
 * Lateralization of brain function --J-Star 23:58, 11 March 2006 (UTC)

Inaccuracies
(Which I've tried to correct) Left and right can be defined precisely using Parity violation in Weak interactions. Of course, the *words* left and right are arbitrary. But nature cares about direction (or more to be more exact, helicity). The article also implicitly confuses *parity* invariance and *translational* invariance.

See this page for more information.

Amcfreely 02:00, 29 April 2006 (UTC)

Left & Right
I agree that most people are using right hand, therefore the parent teach their child to use a "Right" hand (it means correct) and to leave the other hand not be used, so the other hand is called left hand (a hand to be left). Furthermore, "Left" and "Right" did not simply mean the two direction as now we use, we should use "Left hand side" and "Right hand side" because people have been told whcih hand is right and which hand to be left.


 * "If you magnetize a sample of cobalt-60 atoms so that they spin counterclockwise around some axis, the beta radiation resulting from their nuclear decay will be directed opposite that axis. Since counterclockwise may be defined in terms of up, forward, and right, this experiment unambiguously differentiates left from right using only natural elements: If they were reversed, or the atoms spun clockwise, the radiation would follow the spin axis instead of being opposite to it."


 * Here's my question: If doing this experiment requires one to know what right is, how is this of any use, since left is merely the opposite of right? Right appears to be a given here, which seems to be what we want to define. I think that the only things that can be given are up and down, forward and backward, and a third axis, mutually orthogonal to these two, on which left and right lie. For all I know, the colbalt-60 thing does this, but if so, it is poorly explained.


 * Might it be beneficial to think in terms of vectors within dimensions here. If we use the definition of Up and Down discussed below, and replace a gravity well with either the strong, weak, or electromagnetic force, can the ambiguity between left and right be removed by defining each relative to up and down, or are left and right still arbitrary in three dimensions, but finite in four? Master at Arms 22:19, 7 August 2007 (UTC)


 * You need some starting point - the article is on relative direction, not absolute. If your starting point is right, then you don't need an experiment to tell you what left is. But up/down and forward/backward can still be tricky, so there's the right hand rule.
 * The vector cross product is used to define new directions in terms of given ones, in any number of dimensions. In three dimensions you need to define two to get the third. Potatoswatter 05:29, 8 August 2007 (UTC)
 * Woops, not in more than 3. Potatoswatter 05:35, 8 August 2007 (UTC)


 * Never heard the term "absolute direction". How can there be such a thing when all directions are relative?  If there were such a thing as "absolute direction", would that not imply a center of this universe? I don't see the relevance of your reply. Master at Arms 15:57, 10 August 2007 (UTC)

Unexplainable
Is it true you cant explain left and right, you just go in circles? Like: left is not-right. left is west. right is like the shape L. (You always come back to needing a definition for left or right)
 * Yes, that is true. There is no universal explanation unless you start using observations of particle physics. The reason we call the directions "left and right" is simply because long ago, we decided to do so. These definitions have since been carried from generation to generation through word of mouth. --J-Star 07:59, 13 November 2006 (UTC)


 * I do not believe that this is true. The car diagram and its description in this article do unambiguously distinguish left from right, provided that one already understands that we are looking at the names for opposing relative lateral directions. 71.102.186.234 01:41, 20 November 2006 (UTC)

Deleted some fairly wierd vandalism in the car example.--70.157.78.223 01:24, 11 February 2007 (UTC)

isn't the easy definition that left is the direction to the west if you're facing north?~ — Preceding unsigned comment added by 82.30.97.18 (talk) 09:00, 27 September 2012 (UTC)

rewrite
I rewrote a lot. Either the physics & math stuff is clearer now, or just more tortuously lengthy. Lemme know. Potatoswatter 10:02, 19 November 2006 (UTC)

Deleted unhelpful text
"In order to figure out which hand is which you will need a clock, a compass and the sun. Face the sun and check the compass. Before noon, the compass points to your left hand. After noon, it points to your right. If the compass points forward or backward, or the sun is directly overhead forcing you to lie down, take a nap and try again." Alex Law 09:36, 23 February 2007 (UTC)
 * Perhaps I was trying to be too humorous, but maybe it's better to fix it than remove it entirely? Elsewhere in the article it does promise to let you know which hand is which. Potatoswatter 16:46, 23 February 2007 (UTC)
 * Don't worry, it's fixed now. Improvements For All 07:06, 10 July 2007 (UTC)
 * Added clarification that the opposite is true in the southern hemisphere - you guys are always so hemispherist! P g chris (talk) 12:19, 20 January 2008 (UTC)

Up and Down
In one dimension, up and down are undefined / not applicable. In two dimensions, up and down are arbitrary. In three dimensions, up is a vector away from a gravity well, and down is a vector towards a gravity well. So in four dimensions, up is...? An interesting way to view time? Up a time line and down a time line as opposed to seeing time as linear and forward and backward? Master at Arms 21:52, 7 August 2007 (UTC)

You are correct master. Direction is relative to spatial dimension.--207.68.235.128 (talk) 00:40, 25 July 2009 (UTC)

Left/right confusion
I think that i have this problem described - i confuse right and left all the time. People who ask me for directions are rather unlucky - i try to be helpful, but often end up sending them miles away from where they want to go :)

Anyway, i hoped to find the scientific name for this problem here and found an unsourced paragraph.

Can anyone cite something?.. --Amir E. Aharoni (talk) 21:29, 13 July 2008 (UTC)

I don't think that is anything medical. In fact I have the same problem and still do, but any other time I can tell the difference.--207.68.235.128 (talk) 00:39, 25 July 2009 (UTC)

Geometry of natural environment
I made a small edit to this part. It used to say:

''For example, if someone continues walking forward until they have almost circumnavigated the Earth, they will expend much effort only to move backward slightly. This is because, on Earth, people use a spherical coordinate system wherein the direction vectors depend on position.''

I changed the last part because it did not make sense. The coordinate system people on earth (as opposed to where?) use is neither the cause of nor the reason for the fact that you end up in almost the same position when you almost circumnavigate the earth. —Preceding unsigned comment added by 82.139.81.194 (talk) 22:06, 12 October 2009 (UTC) ''Hi! I'm Shewolff. Shewolff77 (talk) 08:27, 3 April 2011 (UTC) I hate to say this so long after you were looking for an answer, but as I recall my friends from Israel, they spoke mainly Hebrew, correct? I know that everyone is bilingual, but in reading is everything in Hebrew? Because if that is the case, SPEAKING ENGLISH and always reading and writing in it are two different things. There is this one test her called the Woodcock Johnson. It proclaims itself not to be able to diagnose this problem that is worse in English speakers than any other language and that problem is called Dyslexia. I have it too so do not feel badly. It occurs all over the world. Whether or not someone is symptomatic is related to the subtype, and there are different subtypes. One includes right/left confusion. I have it. My husband tells me to "right click" and as I am trying to figure out which is the right he makes it worse by saying "you're other right, you're other right", I know you understand. It is a neurological thing. People are born with it, and it is very common. But you should see a neurologist to be sure. I hope this helps. Shewolff77Shewolff77 (talk) 08:27, 3 April 2011 (UTC)

Confusions or paradoxes?
How about some discussion of how left and right reverse for certain things?

Eg if I am looking at a person and a piece of paper, the left side of the person is not the same side as that of the paper, because you take the person's frame of reference in that case?

Segrub (talk) 17:27, 18 January 2010 (UTC)

Left/right confusion referencing
By "refimprove" i actually mean "refimprove". Currently the only significant reference is Houston Chronicle, a local news website. The article is not bad and i am under the impression that i have a condition that is very similar to what is described there (see above on this talk page), but having a reference to an article in a scientific jounal will certainly improve the article. --Amir E. Aharoni (talk) 23:55, 11 May 2010 (UTC)

Other left
There is a page titled Other left that redirects to this page, but the phrase is not mentioned in the article. If the redirect is going to exist, than there should be a brief mention that the phrases "other left" or "other right" are sometimes used jocularly when someone confuses the two. Tad Lincoln (talk) 20:19, 27 May 2011 (UTC)

Categories
This page is categorized as Chirality, which seems incorrect, to me. I’m thinking Relative Direction and Chirality are quite different subjects, so I’d be inclined to take it out. However (following discussions elsewhere), that might be controversial, so I’m raising the matter here first. Are there any objections to me de-categorizing it? Moonraker12 (talk) 15:40, 29 August 2011 (UTC)
 * Is there a more viable supercategory? How about Category:Geometry (which includes symmetry, which in turn includes chirality). bd2412  T 15:48, 29 August 2011 (UTC)
 * Well, finding a supercategory was the problem when I looked before.
 * The articles in cat geom. are pretty heavily mathematical, ( which RD really isn’t); the only one that was similar was Orientation (vector space), and that turned out to be wrongly categorized (I’ve fixed it). So I don’t think RD belongs in Geometry.
 * OTOH, there might be a case for adding Category:Orientation as a subcat of Geometry: It is a way of "measuring the Earth", after all! What do you think? Moonraker12 (talk) 09:57, 31 August 2011 (UTC)


 * OK, done. Moonraker12 (talk) 10:56, 7 September 2011 (UTC)

seriously misleading
some people can't remember their left and right (this is true, you can look it up), if they are in a lifethreatening situation where they need to know fast, this might be the first page they get to. Look at the german page, it's clear: http://de.wikipedia.org/wiki/Rechts but our page actually has the arrow marked "left" pointing to the right of the screen! In a hurry, someone could make a serious mistake here. I propose that the page be made more similar to the german page just linked. Someone's life could depend on this. 82.234.207.120 (talk) 20:19, 16 September 2011 (UTC)
 * in other words, the image linked should be like looking over the person's shoulder, so that the viewer in front of the screen has the same orientation as the person in the image. then the viewer's left-right matches the figure's, instead of being the opposite. 82.234.207.120 (talk) 20:22, 16 September 2011 (UTC)
 * I 100% agree that it would be helpful to have a graphic like the German WP's article but in English. Dialmayo 15:08, 19 March 2024 (UTC)

"Up" and "down"
"Up" and "down" are absolute directions (geocentric coordinate), not relative directions (egocentric coordinates). "Up" means the opposite direction of gravity, and "down" means the direction of gravity.

Think of the situation when you lie down on the bed. Then the relative directions are left, right, forward, backward, "headward", and "footward". --Yejianfei (talk) 18:12, 26 July 2019 (UTC)


 * I agree, and came into the Talk to say so. Regardless of where one's head is relative to one's feet, 'up' is away from the centre of the Earth and 'down' towards it, with the caveats that directions for pictures and videos are usually relative to the Earth as known or imagined within them and that directions for text are relative to its typical orientation if the page is placed vertically. For people outside the significant effects of gravity, I assume they refer to the space they are in by convention as though it were on Earth -- for example, going in a perpendicular direction from the side of a bed someone sleeps on is 'up' -- or they just don't use those directions at all.


 * Similarly, 'forward(s)' and 'backward(s)' are often not perpendicular directions from someone's chest/spine, for example when someone is crawling (even if they are looking at the floor/ground rather than towards the horizon). Salopian (talk) 02:15, 24 August 2020 (UTC)
 * Not always - "up river", "upstream", "upstage", "uptown" and so on are essentially horizontal directions, not vertical. Never mind more metaphorical usages. Johnbod (talk) 10:08, 24 August 2020 (UTC)

Traditions and conventions
There were severe problems here and continue to be others.

The stage directions were impossible to understand without already knowing what they meant, which defeated the point, so I have corrected them in line with the article that is linked there.

The ongoing problems, though, are that these and road signs are given as example of egocentric directions -- but neither are. Stage directions don't rely on which way the actors are facing, but simply the stage itself. Indeed, they exist even when no one is on stage. Road signs are not egocentric either. It's just that it's very usual to view them from the same side and orientation, but if someone somehow views them otherwise (say one is printed on transparent perspex by mistake and the driver is on the wrong side of the road -- or more realistically if the passenger has a disability meaning that their head is tilted to the side) then the directions on the sign are still relative to the road, not the person. A convention which would actually be notable to talk about in this context, but which is omitted, is that up on the sign usually means forwards on the road. I don't know whether this is universal -- certainly arrows on signs for pedestrians (e.g. in shopping centres and transport hubs) are not always like this in every country, causing confusion for people who take it for granted from theirs. Salopian (talk) 02:40, 24 August 2020 (UTC)
 * "defined from the point of view of actors facing the audience" seems clear enough. It doesn't say there has to be an actual actor facing out etc. Johnbod (talk) 10:10, 24 August 2020 (UTC)

Defining left and right mathematically?
Is there a noncircular mathematical definition of left and right? Consider a white sphere, on which a black spot is defined as the top, and on which a yellow spot (at an arc angle of pi/2 from the top) is defined as the front. Now consider the two possible spots (one to be defined as the left side, the other to be defined as the right side) at an arc angle of pi/2 from the top and also from the front: how do you mathematically define the left side (to be coloured red) and the right side (to be coloured green)?

You may neither refer to the human body, neither to clocks, neither to Earth's East and West, nor to any non mathematical artefacts (like letters of the alphabet), since those are not mathematical objects (furthermore, using those objects would give a circular definition). To define the left side and the right side, the only things you are allowed to refer to are the sphere itself, and its defined top and front.

I'm hinting that we have to arbitrarily decide to call one side as the left and the other side as the right, and to use that sphere as a reference standard for all similar spheres!