So in order for the ball to be invisible, it would need to cross 70 meters in 1/250th of a second. That’s 17500 meters every second or 38146 mph! At this point the ball would be moving way, way faster than the speed of sound, and would almost certainly have crumpled up into a little fireball before a goal was even scored.

Of course this is all very theoretical, and completely relies on all the conditions being absolutely perfect plus a striker with the right foot of a god. It all gets a lot more complicated when you start adding bigger objects.

Ultimately our eyes and brain work together so fast, that it would often take something actually moving faster than the speed of light not to be noticed. Even in our example above, it’s possible you might still have an Idea that something went past, just because the light reflecting from the area around the ball was blocked for a split second.

Unfortunately, if the ball was kicked so hard it reached the speed of light, the resulting explosion would in fact level the city surrounding the stadium. Under standard FIFA rules this would almost certainly mean a red card and suspension for the player.

How fast would an object have to go to be invisible to the human eye?