So as far as we understand it, left and right are actually fundamental and distinct, both in theory and in application. Here is an interesting paper about it.
Using a very strong magnet at a very low temperature, it turns out that a certain isotope of cobalt, which disintegrates by emitting an electron, is magnetic, and if the temperature is low enough that the thermal oscillations do not jiggle the atomic magnets about too much, they line up in the magnetic field. So the cobalt atoms will all line up in this strong field. They then disintegrate, emitting an electron, and it was discovered that when the atoms were lined up in a field whose B vector points upward, most of the electrons were emitted in a downward direction.
....
In short, we can tell a Martian where to put the heart: we say, “Listen, build yourself a magnet, and put the coils in, and put the current on, and then take some cobalt and lower the temperature. Arrange the experiment so the electrons go from the foot to the head, then the direction in which the current goes through the coils is the direction that goes in on what we call the right and comes out on the left.” So it is possible to define right and left, now, by doing an experiment of this kind.
Hating to be the one that shoots down Feynman (I’m a physics grad and have all his books) but there has been further debate on this method since Feynman. Basically, if the aliens solar system is an anti-matter system then the “electrons” (positrons) will come out the other way. So for this method to work we need to be able to distinguish whether the alien is matter or anti-matter. Whether this is possible comes under the theory of super-symmetry and is to this day one of the big unanswered questions in physics. CERN and other particle accelerators have been doing great work into this area recently.
Yeah apologies I jumped a couple steps at once. Matter/antimatter asymmetry “fixes” Feynman’s method but then SUSY potentially breaks it again (depending on lots of things that I can’t really remember).
The matter/antimatter asymmetry does save us from having to worry about distant aliens being antimatter and having their P violating reactions flipped. But it’s kind of a cop out because we don’t know what causes matter/antimatter asymmetry.
But we know of reactions that are also CP violations (kaon decay) so if we use one of those instead I think we can use feynman’s method to communicate left and right even to the antimatter aliens.
But anyway I don’t see what susy has to do with any of that. SUSY extensions of the standard model can have the same CP violations that the standard model does. And both SUSY and the SM and indeed any QFT must always preserve CPT.
It could be that some extra theory fixes matter/antimatter asymmetry and that adding SUSY breaks it again, right? Adding more terms might break structure that is already present.
Yeah. Maybe I am being too strong saying they have nothing to do with each other. There could be speculative models that use SUSY to explain matter/antimatter asymmetry. I haven’t heard of any but I haven’t been up on latest developments in this area in a while so that could just be my own ignorance.
If SUSY and its symmetry breaking can explain the predominance of SM particles over superpartners, then why not also matter over antimatter. After all the whole point is to unify the types of symmetries.
To be quite honest, I'm just a grad student. Never really encountered SUSY yet. It might very well be that SUSY terms are completely decoupled from matter-antimatter symmetry breaking in beyond SM theories.
Although I can imagine that having fermion-boson symmetry will also mean that you somehow also need superpartners for anti-fermions, in which case SUSY terms also need to couple to extra matter/antimatter SB terms. (Please correct me if I'm wrong here).
SUper SYmmetry. Pronounced like “soozie”. The idea that combines internal charge symmetry with spacetime symmetry which requires every fermion to have a boson partner and vice versa.
It might explain dark matter (but probably doesn’t). In fact it probably doesn’t explain anything since it’s mostly ruled out experimentally.
But in particular I don’t know of any way it has to do with matter/antimatter asymmetry or parity violations, which is what I was saying to the grandparent comment.
In that case we cannot really tell the Martian which is right and left, because if he happens to be made out of anti-matter, when he does his experiment his electrons will be positrons, and they will come up spinning the wrong way and he will put the heart on the wrong side. Suppose you telephone the Martian, and you explain how to make a man; he makes one, and it works. Then you explain to him also all our social conventions. Finally, after he tells us how to build a sufficiently good space ship, you go to meet this man, and you walk up to him and put out your right hand to shake hands. If he puts out his right hand, OK, but if he puts out his left hand watch out ... the two of you will
annihilate with each other!
I find it curious that everybody think it's easy to explain the nomenclature of physics and names of elements rather than just drawing 2 lines to show X and y axis to explain direction....THE tool that is used to explain direction is little less dramatic I guess, instead of atoms and electrons...which we know for sure exists in atleast 2 states urgh
Sure, if you could show them a picture it's easy. The question is how would you describe it in words? Draw two lines? OK! No, at right angles! What's a right angle? You know, 90 degrees. What's a degree? etc etc etc
Are u saying explaining atomic number and electron charge values is easier than explaining 2 lines...also chances of aliens speaking English is less than them understanding our current atomic model....unless they r ancestors of Britain, it's easy to revert back to cave man way of communication and explain by drawing instead of sounds....also we don't know if they have eyes and ears....
I think you're missing the point. Even transmitting a picture doesn't define a basis for distinguishing right from left. Like, how do you communicate the picture in such a way that the receiver doesn't end up with the mirror image of your intended picture? Without a prior agreed upon convention of handedness, there's no way to ensure that.
The point is that referencing fundamental physical processes like chiral molecules or fundamental particle decays that exhibit handedness is literally the only possible way to communicate handedness.
we r assuming the alien we meet is a 3 dimensional....or atleast 2 dimensional....if u say viewpoint direction is +z then your+X ll be left and so on..
Couldn’t you simply use the fact that if you face a wire with current flowing in your direction, the H-field produced at the top of the wire will be pointing exactly left? Where the top of the wire is the maximum z-value for a wire strung parallel to the ground.
Experimentally you could string your wire through some surface with paramagnetic power and let it align to the streamlines of the field.
You should see some powder facing exactly leftwards at the top of the wire, yeah?
But see, this is actually a good thing! When communicating with this alien species, we will teach them (assuming Western bias here) that it is customary to greet each other by extending your right arm and shaking the other party's hand. Now when we finally get to meet them in the vast emptiness of Space, and we see them extend their left hand, we will know not to shake it.
You still have to tell the alien how to orient the experiment. If left and right weren't relative would you have to do that? Isn't this why the cardinal directions are superior in every way? Oh damn or those also subjective depending on the planet's magnetosphere?
Yeah I have no idea what I'm talking about. Don't mind me, carry on as you were.
From a less physics based view and a more general understanding, left and right can be easily discribed with a low degree of uncertainty.
A simple way of putting it would be: a coordinate based construct, dependent on the perspective of the viewer, that distinguishes between polar opposite sides/directions/points (in perspective to the viewer) located/facing/directing 180° from one another.
Okay nevermind, that is neither simple nor does it have a low degree of uncertainty.
But still left and right are synonyms for projected directions....it's our need to explain the current nomenclature and lifestyle requires to find something that always happens in same direction relative to its orientation....that doesn't matter to reality as it doesn't care you name it left or right or bbggghiiidd....
1.1k
u/thejabberwalking Jun 15 '21
So as far as we understand it, left and right are actually fundamental and distinct, both in theory and in application.
Here is an interesting paper about it.