The physical world is reality to the extent that our relative human consciousness gives it reality. When human consciousness perceived a world limited to a small section of "flat" land, that was their reality and it dictated the parameters of their experience. In the absolute reality of the spiritual, something like getting hit by an 18-wheeler could not happen - nor would there ever be a desire to see if it could. In my limited understanding of what the spiritual realm is about, there are no accidents, there is no disease, no death - there is only one animating force, one perfect Source, and all existence emanates from and reflects that Source. It would not be very wise to challenge an 18-wheeler while still struggling to progress out of the limitations of human consciousness. However, it does help greatly when confronted by human challenges to try as best as possible to reach a more spiritual state of mind. That practice has proved to work very well for me.
Some observations about what you wrote:
Human consciousness is characterized by incomplete knowledge; it forms conclusions which are "relative" to what is perceived. The earth appeared to be flat to a limited consciousness (relative) but the true form of the earth was discovered to be spherical as more information was obtained (absolute).
A building is conceived, designed and then constructed. It's absolute nature is in the original plan. If that building becomes damaged or destroyed (relative state) that does not change the absolute, original nature of that building. If for whatever reason that building is perceived incorrectly, that does not change the true nature of that building (the incorrect perception does create a false, relative reality for someone). The physical (relative) manifestation of the building is ultimately not as substantial as the original (absolute) idea or concept. The idea or concept (spiritual realm) has no limit of time, space or material.
String theory, etc. attempts to describe a relative manifestation of the absolute creative Principal. That absolute creative Principal is Spiritual. There lies the rub: it is difficult, if not impossible, to describe the absolute in relative terms. It is like the "deadly embrace" of computer programming - it creates an infinite circle, a lock-up, escape from which requires external input. I contend that is where human consciousness is now, locked up in a mortal, material illusion. And, the way out is knowledge - spiritual knowledge which may come from science, religion, both or from somewhere yet unknown.
To live in the spiritual is to live in the unlimited realm of perfection with infinite possibilities of expression. That concept is almost incomprehensible to human thought but we are slowly getting closer to the truth.