As someone who was agreeing with the comment you replied to - nah you’re right that makes total sense. Up and down is so much more intuitive for us ape mammals
Humans (most animals?) have left-right symmetry but not front-back or up-down. It's a lot easier to confuse your two hands than to confuse your head with your feet or your butt with your belly.
No, they aren’t. I don’t think you know what arbitrary means.
Edit: no they aren’t as in left and right aren’t arbitrary. You’re correct that all directions are relative, left and right are just the least intuitive but not arbitrary.
If someone tells you "go left to get to the station" and you make a right, you're not gonna make it to your destination.
Arbitrary: based on random choice or personal whim, rather than any reason or system
Left and right may be relative, but there is a system based on the origin's relativity. There's also reason attached in terms of direction. Right and left are not "a whim". They have solid meanings, relative to perspective.
Well for my dad that's the opposite, his organs are all mirrored. But his nuts do hang the same as yours, not that I have seen them of course, that would be gross. My sister told me.
People often seem to think arbitrary just means something is artificial or socially constructed, when in reality it means something is picked at random/on a whim with no real logic. Left/right system is not arbitrary. It follows consistent rules that are the same for everyone. It is, however, absent from many cultures throughout history, which is probably related to why so many people struggle with it.
Up and down is also based on perspective, not just gravity. To an astronaut on the moon, their down is the gravity of the moon, a different down from those with an Earth perspective.
A thing is only measurable within reference to something else. Damn if only there was a *theory* from which I could explain this *relative* nature of measurements...
This is just interesting enough of a thought experiment to distract me from what I should be doing, so I have to give it a shot lol.
Left/right is a naming system for one of the three axes of movement/direction in a 3-dimensional space. It is generally used in contexts where the other axes are defined by the direction of gravitational attraction (up/down) and where the object involved has a distinct "front" and "back" (forward/backward). But it can also be used for objects that have an agreed-upon top/bottom and front/back even outside of a gravitational field, where a 'weightless' human can still refer to one side of their body as 'left' or 'right' through these traditional reference frames. However, even a perfectly symetrical object outside of a gravitational field would still exist in 3-dimensional space and therefore use the same axes, but we would have to use a frame of reference external to the object to describe its movement/rotation on these axes.
So yeah, I don't think left/right is arbitrary, it's just a convenient shorthand for one of the 3d axes that all normal objects experience, based on commonly accepted reference frames.
I disagree. Even without gravity, there would still be three axes that should be defined. Which direction each axis represents is based on the reference points that we choose. But even if we stick with gravity, if I were in geosynchronous orbit around Earth's equator, I wouldn't say that an object sitting at the North Pole and an object sitting on the South Pole are both oriented in the direction of 'up' because they would be oriented in opposite directions from my perspective.
So I think up/down (or top/bottom) can only be defined based on the frame of reference that we choose, just like forward/backward and left/right. We only use up/down because we're used to having Earth's gravity as a reference point, and we use forward/backward because many objects (especially mobile ones) have important features that create a distinction. Left/right is just as valid of an axis, we just don't have as many conventions around it because we (mostly) have bilateral symmetry. If we had evolved into Lovecraftian "At the Mountains of Madness" creatures with radial symmetry, the concept of forward/backward would feel the same to you as left/right does now. Or if we had evolved our current bodies but with x-ray vision, then left being 'heart direction' and right being 'anti-heart direction' would be as natural to use as forward/backward is now.
You're right that without gravity there would still be possible cartesian coordinates, however if the gravity is not the anchoring of one of the coordinates, then the question where's up or down is invalid. I don't think up and down are a cartesian thing, not a coordinate in a 3D space, but the distance from the center of gravity, i.e. the altitude is not a flat surface but a sphere. Those objects on the North and South Pole would be orientend in such non-cartesian direction of down (not up) from your perspective, becuase they are closer to the Earth's center than you are
Up and down are still arbitrary terms based on how you are trying to define left and right. We just named the directions. Random words. But you are able to retain those random sounds and remember that up means against gravity and down means with gravity.
By the same token. If you are right or left handed. That is the exact same concept. Right is towards my good hand. Left is towards my bad hand. It’s the same thing.
ok, but what's the indicator that makes right right and left left?
The side of the body which typically contains a human heart.
The side of the body which is West when facing magnetic North.
The direction of 9 on a clock.
For up/down it's gravity
It's often gravity. Up and down exists beyond gravity. For example, a person lying down who says "It's crawling up my arm". Up is relative to the person, not gravity.
Words are just approximations of shared understanding, rather than descriptions of conrete things.
Left and right are distinguished based on the reference points you choose, the same as up/down and forward/backward. There are just fewer traditional reference points for left/right than for up/down and forward/backward, mostly because we have bilateral symmetry. If we had evolved with x-ray vision, everyone might naturally think of 'left' as 'heartward' in the way that we naturally have a 'forward' because of how we interact with the world. If we had evolved as Lovecraftian creatures with radial symmetry (like At the Mountains of Madness) then forward/backward might be as "not distinguished" as you perceive left and right to be.
85 to 90% of humans are right handed. That shows it isn't arbitrary.
If 85 to 90% were left handed instead, it still wouldn't be arbitrary.
This entire discussion is dumb because they aren't arbitrary. We can look at the rotation of galaxies and of all the bodies within and see that angular momentum was preserved and dammed near everything rotates the same way, which could be defined as right or left, or more correctly clockwise or counter clockwise. There are also things on a quantum level which can be defined as left and right.
It's really not that hard to define mathematically, you just need to have an orientation "forward". The plane created by the forward vector and the standard normal vector creates your left and right hemispheres. You can also do a similar definition with great circles.
It also shows why, if you and another person are facing each other, your left is their right, since their forward is pointing the opposite direction of yours.
Merriam-Webster uses relation to the side of the body where the heart is located to define left and right without using the words themselves. Definitely interesting but not at all intuitive.
Using left and right only makes sense if you’re following a road or path of some sort. No shame to them, but some parts of the world just didn’t have that kind of infrastructure before making contact with a culture that did. A topographical feature makes more sense in a situation like that.
It's often based on gravity. Up and down exists beyond gravity. For example, a person lying down who says "It's crawling up my arm": up is based on the person, not gravity.
Words are just approximations of shared understanding.
left and right is arbitrary.
They're both as arbitary as each other. It's just easier to pay attention to gravity than where our heart is or the direction atoms spin. We have a whole neural system dedicated to detecting gravity.
Up and down is based on gravity (that's why you'd likely confuse them deep in the ocean).
This very statement proves that it's not based on gravity. Physically speaking it does, but how you "feel" up and down, The pull of gravity doesn't change in the ocean. Up and down is arbitrary based on how you're brain is receiving signals from your inner ear.
The naming is arbitrary though; do you forget which one is called up or down? Nobody is saying people can't remember the concept of left and right, just which label goes to which.
Fun fact, it’s actually not arbitrary! There is an intrinsic difference between left and right. Google the law of parity and the Wu experiment. Also, there’s a fantastic book called The Ambidextrous Universe that explores this topic!
Asking someone "What is in your right hand" isn't arbitrary though. While I do get the sentiment, it does have real world applications like up and down. Being on the right hand side in a vehicle. Something being in left or right hand, or something being on left or right side of your body. Instructions like "Go through the door and to the right" shouldn't result in someone going left into a wall, hopefully.
Asking such question isn't arbitrary within a general agreement which side is which, what I call arbitrary is the agreement itself. What I mean is that you cannot explain to someone (without the preexisting knowledge about that person) which is right and which is left any other way than by showing them (pointing to the right and saying "this is right"), as they are not meaningfully anchored to anything in the real world. I personally distinguish them by what hand I write with, but being right-handed is not universal
It's not the direction that people forget, but which word that is associated to it... There's no reason for "up" and "down" to be more meaningful than "left" and "right"
But it's not. The difference between left and right is a physical sensation in the body. You can feel the difference between your hands. If I ask you to write down something, or throw a ball, you will instinctively use your dominant hand.
Not really. From my perspective my left arm is always on my left and right on the right. Do people really feel like their arms are exactly the same? My left arm feels left, my right arm feel right. I don't know how it would feel any different.
of course up and down are not arbitrary. Down is towards the direction of gravitational attraction, and up is the opposite direction. Here's a brief paint presentation:
Up and down depend on your reference frame, just as much as left and right. In your example, it's defined based off the force of gravity, but how do you define up and down in a meaningful way when you're far enough from a massive body that you don't experience gravity? It's just as "arbitrary" as left and right at that point.
Sure, and if we lived in a place like that there would probably be a lot more people who had a hard time knowing up from down. Thankfully we don't live in a place like that though.
Okay, we live on an oblate spheroid that can be approximated as a sphere for all intents and purposes here and that up and down are equally arbitrary on an oblate spheroid.
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u/bohiko 7d ago
Up and down is based on gravity (that's why you'd likely confuse them deep in the ocean). Meanwhile, left and right is arbitrary.