It’s long been an axiom of physics that everything is constantly in motion, due to the cosmic background stretching of the Universe. At least that’s what Brian Greene tells us, and in this case I’m inclined to believe him. No matter that everything he concludes from this fact is not even false.
Yet, al a cartes Thomas Kuhn, we know that old washed up ideas die hard. This is the case with a little gem I was taught in high school physics concerning an object falling toward the Earth, after been thrown away from it. Specifically, if you throw an object straight up, gravity will cause its acceleration/speed to decrease until reaching 0mph, at which point it will begin increasing its acceleration/speed in the opposite vector. Your immediate reaction should be that the phrase “at which point” is inherently ambiguous. Yes it is, and that’s half the problem. Let’s look at a chart provided by a propaganda website.
According to this diagram, an object will be basically at rest right where you see the a= 0 m/s2. Of course, none of these wizards can tell us how long the object will be at rest. That’s because it’s impossible to tell. Why is it impossible to tell? Despite the fantasies of William Tells, the object is never at rest. We know from contemporary science that nothing is ever at rest! Well then, to paraphrase Hume, whence the cognitive dissonance? Basically people have a hard time conceptualizing an instant change in vector – it makes them nervous. As Kant described, the human mind has to impose mental structures on physical perception in order to make sense of it. Well, in the case of “in between time” (the real culprit here), the structure happens to be irrational. It’s what gives us Zeno’s Paradox – the idea that you must be able to always divide time/distance sequences. This idea turns out to be false, as proclaimed loudly and clearly by Bertrand Russell. Well, it’s also false in the case of allegedly negated vectors. There doesn’t have to be a “zero” in between positive and negative opposite vectors. Hard to rap your mind around, but take a look at this adjusted diagram, which should help (although we can’t ever fully understand physical reality, since we play too many language games).
Alright. The concept of “0mph” can now be put to rest. No matter what science fiction authors say. Very simply, when you throw up an object into the air, it never stops moving. After all, if it did stop moving, how would it ever get back to you, without something to force it back down? Few people think of the most obvious dilemmas in their allegedly scientific reasoning.
Go ahead and try this one out on your physics friends. Have them tell you how long an object supposedly stays at rest for, at the peak of the falling down curve. They won’t be able to. If pressed, they will tell you that it is an infinitely short moment. And by now my readers can’t fall prey to those shenanigans.