I was discussing elsewhere if a photon has mass, there are many reasons to argue that it does, it imparts a force as it is emitted, absorbed or reflected. A mirrored sphere would reflect light and if the sphere was accelerated the blue/red shifting of light should lead to unequal forces. If you place it in a gravity field/well, we know the photons path is bent by gravity, so the sphere should also weigh slightly more too.
I even looked on opinion as to if light might create a slight gravity it's self, and surprisingly the majority of opinions (those considered expert in Relativity) seemed to indicate it would, or could. But, what of a stopped photon? Well while photons can be stopped, I considered this to be imperfect. So instead I wondered if a solenoid creating a steady magnetic field could be likened to a static photon, which seems reasonable a photon is released by varying a magnetic field (current in a wire). And so should a solenoid have increased inertia, or an inertial like force? Yes, and I will prove it. Let's take a square solenoid, feed with steady DC, with sides that are 1 light minute apart. Let's label the sides left, right, top and bottom. We would see top and bottom mutually repel, and left and right mutually repel due to the magnetic fields they each create, but the forces would overall balance. So let's start with it stationary, and suddenly accelerate all parts at once towards the right, without any deformation occurring, putting aside and difficulty with simultaneity. Now since propagation of any changes in the magnetic field are limited to C, as the left side moves toward the right, it actually thinks it is getting closer to the right side, the magnetic field the right side creates in that area near the left is still based in it's old location and will be for 1 minute. Additionally the right side sees it is getting further away from the left as again it sees the old location of the left, this decreases the repulsion the right side encounters. So the force on the left side increases and the force on the right side decreases which leads to a net force opposing the acceleration. This would seem identical to inertia, but could also be seen as a hysteresis against space effect. John
