Paul Fuller wrote:
> I don't think I implied that it is random.  If so then let me clear that 
> up.

Sorry. Random is a bad word to use.

That things work the same no matter which way you face is the "random" 
part. It's not necessary that things work that way. But it seems they 
do. *Given* that, conservation of angular momentum is a result.

> I don't think you can explain though why those principles are true 
> without essentially coming back to restating them or observing that 
> we've never seen them to be broken.  

Right. What I was trying to express is that "angular momentum is 
conserved" isn't really the "we've never seen it to be broken" part. 
It's the "experiments run the same no matter which way you face" that's 
the "never seen to be broken part".  Conservation of angular momentum is 
an effect, not a cause.

> And it is cool :)

Yup.

-- 
   Darren New / San Diego, CA, USA (PST)
     Remember the good old days, when we
     used to complain about cryptography
     being export-restricted?

Post a reply to this message

Warp wrote:
>   If we express that in overly simple terms: If a rotating system consists
> of several parts, bringing those parts closer together requires energy.

Yes.

> If those parts are later pulled apart, that energy is released?

Assuming it hasn't dissipated somewhere, yes.  Think of spinning around 
an axle, reeling in a weight on a string. Now let the weight pay out, 
and you can make it do work like play a music box.

>   Or perhaps in another way: Bringing more variation to local spinning
> at different parts of the system requires energy,

I don't think the spinning and the energy are particularly connected. If 
you're talking about closed systems, the energy doesn't go away, it just 
moves around. It may move to a place (like heat) from which you can't 
move it back.

>   (In other words, in a closed system getting two discs to rotate
> independently in the same direction requires energy. Colliding those
> discs so that they will start rotating as one single object will release
> that energy?)

I don't think that's right, no. In a closed system, you can move energy 
around but not create or destroy it. Spinning them in opposite 
directions requires moving energy from somewhere else, like a spring or 
a chemical explosion or something. In a closed system, you can't get 
them both rotating in the same direction without something else rotating 
in a different direction.

-- 
   Darren New / San Diego, CA, USA (PST)
     Remember the good old days, when we
     used to complain about cryptography
     being export-restricted?

Post a reply to this message

Warp wrote:
>   A theoretical question: Can mass be converted to other forms of energy?

Mass *is* energy. That's where energy is stored. That's why things with 
lots of kinetic energy are heavier.  That's why a helium atom weighs 
less than four hydrogen atoms.   E=mc^2.

>   Assuming yes, how does this conversion affect angular momentum?

It doesn't. It doesn't go anywhere.  It's all the same stuff.

-- 
   Darren New / San Diego, CA, USA (PST)
     Remember the good old days, when we
     used to complain about cryptography
     being export-restricted?

Post a reply to this message

Darren New <dne### [at] sanrrcom> wrote:
> Warp wrote:
> >   A theoretical question: Can mass be converted to other forms of energy?

> Mass *is* energy. That's where energy is stored. That's why things with 
> lots of kinetic energy are heavier.  That's why a helium atom weighs 
> less than four hydrogen atoms.   E=mc^2.

  That didn't really answer my question.

> >   Assuming yes, how does this conversion affect angular momentum?

> It doesn't. It doesn't go anywhere.  It's all the same stuff.

  Since angular momentum is dependent on mass, that means that eg. heat
has mass?

-- 
                                                          - Warp

Post a reply to this message

Paul Fuller <pgf### [at] optusnetcomau> wrote:
> >   Assuming yes, how does this conversion affect angular momentum?
> > 
> Simple - a photon carries angular momentum.

  Is electromagnetic radiation the only possible form of energy?

-- 
                                                          - Warp

Post a reply to this message

Warp wrote:
> Paul Fuller <pgf### [at] optusnetcomau> wrote:
>>>   Assuming yes, how does this conversion affect angular momentum?
>>>
>> Simple - a photon carries angular momentum.
> 
>   Is electromagnetic radiation the only possible form of energy?
> 
No.

Are you being obtuse ?

Let me re-phrase that.  You are being obtuse.  Is it deliberate ?

Post a reply to this message

Paul Fuller <pgf### [at] optusnetcomau> wrote:
> Warp wrote:
> > Paul Fuller <pgf### [at] optusnetcomau> wrote:
> >>>   Assuming yes, how does this conversion affect angular momentum?
> >>>
> >> Simple - a photon carries angular momentum.
> > 
> >   Is electromagnetic radiation the only possible form of energy?
> > 
> No.

> Are you being obtuse ?

> Let me re-phrase that.  You are being obtuse.  Is it deliberate ?

  Why the hell are you constantly trying to turn this into a flamewar?

  I asked if mass can be converted to other forms of energy, and if this
is so, what happens to the angular momentum. Your answer to this was that
"a photon carries angular momentum". That seems to clearly imply that all
forms of energy consist of photons. When I ask you if what you are trying
to say is that all forms of energy consist of photons you call me obtuse.

  Well, you know what? Go fuck yourself. I'm tired of your condescending
attitude.

-- 
                                                          - Warp

Post a reply to this message

Warp wrote:
> Darren New <dne### [at] sanrrcom> wrote:
>> Warp wrote:
>>>   A theoretical question: Can mass be converted to other forms of energy?

Nuclear fission.
Nuclear fusion.
Matter-antimatter annihilation.

In each case the mass lost is accounted for by emitted photons.

Post a reply to this message

> 
>   Well, you know what? Go fuck yourself. I'm tired of your condescending
> attitude.

Expert speaking...

Fabien.

Post a reply to this message

Warp wrote:
> Paul Fuller <pgf### [at] optusnetcomau> wrote:
>> Warp wrote:
>>> Paul Fuller <pgf### [at] optusnetcomau> wrote:
>>>>>   Assuming yes, how does this conversion affect angular momentum?
>>>>>
>>>> Simple - a photon carries angular momentum.
>>>   Is electromagnetic radiation the only possible form of energy?
>>>
>> No.
> 
>> Are you being obtuse ?
> 
>> Let me re-phrase that.  You are being obtuse.  Is it deliberate ?
> 
>   Why the hell are you constantly trying to turn this into a flamewar?
> 
>   I asked if mass can be converted to other forms of energy, and if this
> is so, what happens to the angular momentum. Your answer to this was that
> "a photon carries angular momentum". That seems to clearly imply that all
> forms of energy consist of photons. When I ask you if what you are trying
> to say is that all forms of energy consist of photons you call me obtuse.
> 
>   Well, you know what? Go fuck yourself. I'm tired of your condescending
> attitude.
> 
I guess there is an equal and opposite reaction :)

Post a reply to this message