Particle models assume that objects collide because their substances can’t occupy the same space at the same time. Waves superpose but substances don’t, so Newton concluded that matter only moves when other matter hits it.
Yet gravity ignores this convention, as the sun holds the earth in orbit from millions of miles away with only space between. Following Newton, the standard model concluded that graviton particles must cause gravity but Einstein’s cause wasn’t a particle at all. He concluded that the earth attracts objects around it by changing their space and time. More details follow, but experiments confirm that he was right, so matter can change space and time, but how can that happen?
Particles can collide with other particles but not with the time and space they move within, so how does matter affect either? A billiard ball can’t contract the table it rolls on, or slow down a movie of it rolling, but relativity lets its matter do just that. The conclusion that matter changes space and time then challenges the idea that it is made of particles, as special relativity illustrates.