Two clarifications are in order.
1. A mathematical ‘physicist’ is not a physicist. A mathematical ‘physicist’ is exactly the opposite of a physicist. A mathematical ‘physicist’ is simply a mathematician who describes behavior with equations. A genuine physicist is someone who explains mechanisms and causes.
In fact, ALL, absolutely ALL explanations that mathematical ‘physicists’ provide for the invisible, intangible workings of the Universe are irrational, from black holes to Big Bang creationism to inexistent dark matter and particles at two places at once.
Nonphysicist Max Born opined once that physics is becoming more and more abstract. What mathematician Born didn’t realize is that abstract is the opposite of physical. Physicists suggest that mathematical ‘physicist’ should be relabeled as mathematical ‘abstracist’ so that layman are not deceived or confused.

A theory is not a description, mathematical or otherwise. A theory is an explanation. A physicist is someone who can explain a mechanism, especially, of phenomena such as magnetism or gravity that are mediated by invisible, intangible objects. To theorize that there are no physical mediators involved in such phenomena is to propose black magic: action at a distance.
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Einstein discovered an equation: a mathematical description. Together with other nonphysicists such as Lorentz, Poincare, and Minkowski, they converged on an irrational theory [explanation, physical interpretation, mechanism]: that gravity is caused by the bending of a mathematical concept they dubbed spacetime. This ‘physical’ interpretation was gradually accepted by the mathematical establishment because it was a departure from Newton’s unworkable discrete particle hypothesis.
Spacetime is a popular euphemism among nonphysicists that stands for ‘four number lines’… which mathematicians misleadingly call ‘dimensions’ or ‘coordinates’.
“…one can describe the position of a point in space by three numbers, or coordinates. For instance, one can say that a point in a room is seven feet from one wall, three feet from another, and five feet above the floor. Or one could specify that a point was at a certain latitude and longitude and a certain height above sea level. One is free to use any three suitable coordinates… in relativity, one could use a new time coordinate…”

Hawking, A Brief History of Time (1988).