5 Comments
User's avatar
Men's Media Network's avatar

Newton’s Third Law may not fit your macro model of the universe, but it’s never once let me down for engineering purposes.

Expand full comment
Dr Ferdinand Santos III's avatar

Kinetic energy is different than Newton's idea of a reaction.

Expand full comment
Stuart Hutt's avatar

It’s all Scientism. I’m waiting for Einstein to pull a rabbit from his hat.

Expand full comment
Dr Ferdinand Santos III's avatar

Yes Einstein the stage performer. He pulled more than just rabbits from his hat. He conjured up complete fantasy worlds, all proven by his maths :) None of these fantasies are falsifiable. I wonder why Popper never applied his axiom to the Einstotle cult.

Expand full comment
Pat Cusack's avatar

I applaud your scholarly evisceration of Einsteinian “space-time” nonsense, but your hubris in impugning Newton’s 3rd law astonishes me. As an engineer, I can assure you Newton’s 3rd law will be working in the cases you describe, despite your inability to ‘model’ the penetration, deformation and damage done to the various ‘targets’ (face, body, wall, target) by the ‘missiles’ (fist, arrow, hammer, bullet) you threw at them.

• Your difficulty lies in not being able to model the rapid changes in the motions, dynamic distortions, changing contact areas, and structural damage of each object in real time.

Given sufficient time and money, each impact could be modelled in a supercomputer. With a Finite Element Model (FEM) of your various missiles and targets, a Finite Element Analysis (FEA) program would handle the dynamic changes in the anisotropic properties of each body as it moves, deforms, or fractures during the brief interaction period. That FEA would apply Newton’s 3rd law as a ‘boundary condition’ where the Elements of each FEM were in contact and ensure equal and opposite Force Elements act perpendicular to Contact Elements and allow equal and opposite friction effects to act on (and parallel to) those Contact Elements, as they slide.

• Your sense of the word “reaction” seems to refer to the huge difference between the EFFECTS an impact has on your selected ‘stationary’ objects, and the EFFECTS of the same impact on your selected ‘moving’ objects. That huge difference seems to have distracted you from the mutual contact FORCE itself, which occurred before (and caused) all those subsequent EFFECTS. But that difference relates to the huge differences between the colliding bodies, not to a flaw in the 3rd law.

Newtonian ‘actions’ and ‘reactions’ are ‘mirror images’ of each other and are as inextricably linked as you and your image in a mirror are linked. One may seem to be ‘causal’ and the other its ‘effect’, due solely to our human awareness of sequential time. But inanimate objects have no perception of time; each simply ‘reacts’ to the other, and that common ‘reaction’ force acts equally in both directions at the same instant. Whether its EFFECT is insignificant or devastating depends solely on the NATURE of each object.

Expand full comment