Was Crocodile stronger at Marineford? Or was he holding back in Alabasta?

 During the Alabasta arc, Crocodile displayed a level of power that was initially considered overwhelming by the Straw Hat Pirates. He possessed the Logia-type Devil Fruit called the Suna Suna no Mi (Sand-Sand Fruit), which granted him the ability to control and transform into sand. He had a reputation as a Shichibukai and controlled the desert kingdom of Alabasta from the shadows. His strength was showcased through his battles with Luffy and others. At Marineford, Crocodile was present as part of the war that took place at Marine Headquarters. While he did participate in the battle, he didn't display the same level of dominance as some other powerful characters present. This has led fans to speculate that he might not have been as strong as initially portrayed in Alabasta. It's important to note that power scaling and character abilities can be subject to interpretation and development by the author. Oda often keeps details deliberately open-ended to keep the story intriguing.

Can physics be used to explain and/or predict aspects of the math universe?

 Physics and mathematics are closely related fields, and both are used to explain and understand the world around us. In many cases, mathematical concepts and principles are used to describe and predict the behavior of physical systems. For example, the laws of motion and gravitation, which were first described by Isaac Newton, can be expressed mathematically and used to predict the motion of objects in the physical world. Similarly, Einstein's theory of relativity uses mathematical equations to explain how objects move at very high speeds and in the presence of strong gravitational fields. So, in many ways, physics can be used to explain and predict aspects of the mathematical universe.