You can power a sailboat with a giant fan. What's the problem? Don't point it at the sail though - just point it away from the boat. :)
But anyway the difference here is that the "wind" is not being "pulled" from external sources (like real wind), it's created by Pioneer. And that makes a huge difference.
With wind, the fan pulls the wind (which creates force), and also pushes the wind (which also creates force).
Next you impact the wind into the sail, which subtracts from our force (since the wind is pushing in the wrong direction).
And finally the wind "bounces" off the sail, also subtracting, and leaving you with no net force.
i.e. +2 then -2.
With pioneer one step is missing - the force from pulling the wind (since the photons are created on the fly). So you have +1 then -2, leaving you with a net force of -1.
PS. If you don't understand why pulling and pushing the wind counts as two forces, think of a compressor which sucks in air and stores it. It still causes motion by pulling the air, but it doesn't push it.
But anyway the difference here is that the "wind" is not being "pulled" from external sources (like real wind), it's created by Pioneer. And that makes a huge difference.
With wind, the fan pulls the wind (which creates force), and also pushes the wind (which also creates force).
Next you impact the wind into the sail, which subtracts from our force (since the wind is pushing in the wrong direction).
And finally the wind "bounces" off the sail, also subtracting, and leaving you with no net force.
i.e. +2 then -2.
With pioneer one step is missing - the force from pulling the wind (since the photons are created on the fly). So you have +1 then -2, leaving you with a net force of -1.
PS. If you don't understand why pulling and pushing the wind counts as two forces, think of a compressor which sucks in air and stores it. It still causes motion by pulling the air, but it doesn't push it.