Left and Right

[Brugel]

In one of his Maths books the author Martin Gardner talks about the following thought experiment. Imagine that you make contact with a being from some far part of the galaxy and communicate with him using a series of electronic signals. Thus you are able to understand him, and he understands you. At one point, you say to him "My heart is on my left side" and he replies "What does left mean?" How would you explain this if you can only communicate verbally and not visually?

According to Gardner, the difference between left and right could not be explained until 1956 when it was discovered that neutrinos always (or almost always) travel in an anti-clockwise direction. Can anyone explain this to me?

[ABerrant]

http://nobelprize.org...1957/yang-lecture.pdf

http://nobelprize.org.../1957/lee-lecture.pdf

http://nobelprize.org...980/fitch-lecture.pdf

[jake-the-peg]

Ooh Yes - love this one - actually he's shamelessly stolen this one from Richard Feynman (unless he stole it first of course - he would've if he thought it good enough)

It's all to do with symmetries and their deep relationship with conservation laws. (Noether's theorum)

So for example the fact that the physics does not change when you change direction and perform the same experiment facing the other way is linked to the conservation of angular momentum.

such "invariance" in space and time are related to conservation of linear momentum and Energy.

So for a long time it was speculated that "handedness" or chirality too was an invaiance.

The Yang-Lee experiment showed that some radioactive decays in a magnetic field have a handedness and therefore there was no general symmetry

Here's a nice little schematic explaining it

http://universe-review.ca/I15-31-parity.jpg

[mibn2cweus]

How would you corroberate the direction of spin with the direction of the magnetic field when spin direction clockwise/anticlockwise and north/south poles are assigned arbitrarily?