[thedoc (OP)]

AndyJohnD asked the Naked Scientists:
   
Is the right hand rule of torque relevant throughout the Universe?

Does the direction of torque depend on the direction of the earth's rotation about its axis or the direction of the earth's rotation about the sun?
So why is i x j = k and not -k?
What do you think?

[alancalverd]

The "right hand rule" is merely a mathematical convention to describe rotational phenomena. You can generate the equations of rotation by integrating the equations of linear motion along a curved path for each particle. It makes sense to use the same sign convention for all rotations in the same sense. There's no reason why the physics should change throughout the universe, so no reason to change the sign convention. 

[JP]

Just to add a little note to what Alan said (which is absolutely correct), when I teach rotation, I find the easiest way to grasp it is to think about how to most easily describe the rotation of a rotating object.  Clearly if it's rotating about an axis, we can pin down that axis.  Then what remains it to describe in what sense it rotates about that axis, i.e. clockwise or counter-clockwise as viewed from a particular reference frame.  We can define this by coming up with a rule, and we choose the "right hand rule" just so that we all agree on notation.  So we put an arrow head on our rotation axis and say that the direction of this axis specifies rotation of the object via the right hand rule.

So in summary, we've defined a rotation axis and used the right hand rule to specify in what sense the object is rotation about the axis, which is sufficient to describe rotation about that axis.

[acsinuk]

In my view the right hand rule is essential to the universe but surely it requires an electro-magnetic force to give celestrial bodies enough torque to spin.
CliveS

[PmbPhy]

In my view the right hand rule is essential to the universe but surely it requires an electro-magnetic force to give celestrial bodies enough torque to spin.
CliveS

I don't understand. What exactly do you mean by you're "view"? Is this something you proved using the laws of physics or is it the way you believe things work by guessing?

There is nothing inherent to right-handedness in the laws of physics. In fact if you were trying to communicate which was the right and which was the left merely by transmitting a message the there'd be no way to communicate which was which using just classical mechanics or electrodynamics. That'd be quite literally impossible. Also, celestial bodies aren't rotating because of any torque on them and they don't all rotate in the same direction either. And they don’t get their spin from anything to do with electrodynamics. It comes from the gravitational force and conservation of angular momentum.

[acsinuk]

PMB
"There is nothing inherent to right-handedness in the laws of physics."  Exactly, physics needs to be revised so that it incorporates this fundamental electrical factual evidence!
CliveS

[JP]

PMB
"There is nothing inherent to right-handedness in the laws of physics."  Exactly, physics needs to be revised so that it incorporates this fundamental electrical factual evidence!
CliveS

That sounds like an excellent discussion for the New Theories forum!

[acsinuk]

NO not yet.  There is evidence that the solar wind was a twisted magnetic flux tube that cannot be explained by normal physics.  JP the doc is right; we need to consider very carefully the electromagnetic force that twists or spins things in deep space.
CliveS

[PmbPhy]

PMB
"There is nothing inherent to right-handedness in the laws of physics."  Exactly, physics needs to be revised so that it incorporates this fundamental electrical factual evidence!
CliveS

Since when has that ever not been the case?

I was talking about classical physics anyway. That's why I wrote "using just classical mechanics or electrodynamics." I think it might be possible using particle physics to distinguish through a comminication which is left and which is right.