Electrons are only one-dimensional matter so photons can fill their other dimensions to make them move as light does. The matter-photon hybrid is held together because quantum entanglement unifies entities that restart at the same point. Electrons then always move, as light does, but slower because they are only like light on two dimensions.
In contrast, quarks that combine into atoms have a symmetric distribution, so they don’t always move as electrons do. Yet they still have free channels for photons to occupy, as their higher generations show, so atoms can acquire photons to move as electrons do. Light hitting a solar sail then moves it because its matter absorbs photons that bias its distribution in one direction. The sail matter already trembles in all directions, so adding photons that bias its tremble one way moves it.
The alternative idea that photon particles push the sail struggles because photons have no mass, and relativistic mass is a troublesome concept in physics. The simpler view is that the sail moves because it acquires photons that bias the quantum field around it.
This acquisition also explains why mass increases as objects go faster, as more photons produce more interference, which increases the processing that in this model is mass. The increase isn’t linear because interference doesn’t increase linearly with load, as networks like the Internet show. Mass then increases as movement increases, as relativity states.
Matter then has inertia, a tendency to keep on moving, because when it acquires photons to make it move, they stay with it, to keep it moving the same way.
Special relativity replaces the idea that matter moves because particles push it with the idea that it moves because space and time change. General relativity then adds that a large mass like the earth can move the matter around it in the same way.