The ‘missing’ kinetic energy is evenly distributed across the matter within the field. So if one of these devices is powered on and gets hit by a cannonball, the cannonball will slow down to a leisurely pace of 50m/s (about 100mph) and therefore possibly just bounce off whatever armor the device has—but (if the cannonball was initially travelling very fast) the device will jolt backwards in response to the ‘virtual impact’ a split second prior to the actual impact.
With sufficient kinetic energy input, the “jolt backwards” gets strong enough to destroy the entire vehicle or at least damage some critical component and/or the humans inside.
A worldbuilder could, of course, get rid of this part too, and have the energy just get deleted. But that makes the device even more physics-violating than it already was.
Kinetic energy distributed evenly across the whole volume of the field does not change the relative positions of the atoms in the field. Consider: Suppose I am in a 10,000lb vehicle that is driving on a road that cuts along the side of a cliff, and then a 10,000lb bomb explodes right beside, hurling the vehicle into the cliff. The vehicle and its occupants will be unharmed. Because the vast majority of the energy will be evenly distributed across the vehicle, causing it to move uniformly towards the cliff wall; then, when it impacts the cliff wall, the cliff wall will be “slowed down” and the energy transferred to pushing the vehicle back towards the explosion. So the net effect will be that the explosive energy will be transferred straight to the cliff through the vehicle as medium, except for the energy associated with a ~300lb shockwave moving only 50m/s hitting the vehicle and a cliff wall moving only 50m/s hitting the vehicle on the other side. (OK, the latter will be pretty painful, but only about as bad as a regular car accident.) And that’s for a 10,000 lb bomb.
We could experiment with tuning the constants of this world, such that the threshold is only 20m/s perhaps. That might be too radical though.
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With sufficient kinetic energy input, the “jolt backwards” gets strong enough to destroy the entire vehicle or at least damage some critical component and/or the humans inside.
A worldbuilder could, of course, get rid of this part too, and have the energy just get deleted. But that makes the device even more physics-violating than it already was.
Kinetic energy distributed evenly across the whole volume of the field does not change the relative positions of the atoms in the field. Consider: Suppose I am in a 10,000lb vehicle that is driving on a road that cuts along the side of a cliff, and then a 10,000lb bomb explodes right beside, hurling the vehicle into the cliff. The vehicle and its occupants will be unharmed. Because the vast majority of the energy will be evenly distributed across the vehicle, causing it to move uniformly towards the cliff wall; then, when it impacts the cliff wall, the cliff wall will be “slowed down” and the energy transferred to pushing the vehicle back towards the explosion. So the net effect will be that the explosive energy will be transferred straight to the cliff through the vehicle as medium, except for the energy associated with a ~300lb shockwave moving only 50m/s hitting the vehicle and a cliff wall moving only 50m/s hitting the vehicle on the other side. (OK, the latter will be pretty painful, but only about as bad as a regular car accident.) And that’s for a 10,000 lb bomb.
We could experiment with tuning the constants of this world, such that the threshold is only 20m/s perhaps. That might be too radical though.