newtonian mechanics - Would a pendulum swing indefinitely in a frictionless vacuum?

I am attempting to settle a friendly bet. Would a pendulum swing indefinitely in a hypothetical vacuum (i.e. no air resistance) having a hypothetical frictionless bearing (i.e. no energy lost due to friction) assuming the following

1. 
   

   The frictionless vacuum is on Earth (9.8 m/s^2).

   
   


2. 
   
   

   The pendulum is already in motion and no other external forces other than gravity act on the pendulum.

   
   

Answer

Yes. this is a perfect case of a so called perpetuum mobile (see here).

It would respresent a perfect (ideal) non-dissipative system where entropy production $d_iS/dt=0$, in accordance with the 2nd law of thermodynamics. Indeed the first law of thermodynamics (energy conservation) does not say much about this, except that no term for energy loss included.

However, the system must really be non-dissipative, that means no type of friction or dissipative loss of energy in any way, such as friction in the elements of the pendulum etc.