The really hard ones are too damn hard, and the really simple ones are often “just the way things are”. Or they may be really, really difficult questions in disguise. What heavy objects are bending is space itself. The stretching of space caused by the Earth’s gravity (well… that is Earth’s gravity) increases the diameter of the Earth by about 18mm. That is, the diameter you get by measuring the equator and dividing by ( ) is the “flat space diameter”, the diameter you get by physically dropping a rope through the planet is the true, “curved space diameter”, and the difference between these two is 18mm.