On Mon, Nov 21, 2016 at 07:58:10PM -0500, Richard Aiken wrote:
> On Mon, Nov 21, 2016 at 6:23 PM, Tim <xxxxxx@little-possums.net> wrote:
>
> > After that, they would
> > need to test in a wider variety of conditions to rule out other
> > possibilities such as local interaction with Earth's magnetic field.
>
>
> But if the effect is due to interaction with a weak magnetic field,
> couldn't it still work, by purposely including a permanent magnet in the
> device?

There's (at least) two types of interaction that might be happening
with magnetic fields.  One is just ordinary dipole torque, which would
register on a torque balance of the type used in NASA's experimental
setup.  That wouldn't produce net force at all.

The other would be much more interesting, and would involve a net
force between the source of the magnetic field (Earth) and the device.
There isn't a known mechanism for this (in a pretty much uniform
field), but it would not run counter to energy/momentum conservation
laws.  The downside is that a device moving through the field would
have to expend a lot more power than a stationary one for the same
thrust, and the thrust would also depend upon the strength of the
field.

In both cases, carrying a permanent magnet along with the device would
not produce any net thrust as the forces and torques on the magnet
would exactly balance the forces and torques on the device.

As far as the "doesn't break conservation of momentum" claim by the
inventor goes, his math is hogwash.  If this thing works, it's by some
other currently unknown laws of physics.

- Tim