OOAK Table Tennis Forum

it is clear that soccer balls can "wobble". See, for example, the video below. If you run the video in slow motion (from about 3.30 onwards), it is clear that the trajectory of the ball changes in mid flight. This is "wobble", if anything is. And it continues to "wobble" no matter how many times you replay it. The fact that the ball still "wobbles" even though you can now "predict" with 100% accuracy where the ball is going (because you have seen the clip many times before) shows that "wobble" is not simply an illusion generated by mispredicted trajectory.

... soccer balls - even light ones - are too heavy to be pushed around by tiny air currents? Misperception (a la Kees's explanation). No, light balls most definitely swing back against their original direction. Lack of spin producing some sort of Bernoulli effect? ...

Yes there has - there are lots of studies in baseball on the knuckle ball effect

Recently I read a German article (I forgot which/where, probably on a German forum) which dealt with wobble, arguing that it is a trick played on players by their brains and not an actual phenomenon. The writer argued (if I remember correctly) that according to science objects cannot change their trajectory unless a force is working on them; so if nothing is influencing the ball during its trajectory, it cannot change direction or speed in mid-air. However, players can easily think some balls just do exactly that, for the observation of the ball's trajectory is not continuous, but consists of ascertaining visually 4 to 5 times during its flight the position of the ball and with that information the brain works out the complete trajectory by extrapolation. So players do not actually see the trajectory as a whole, but construct it in their mind, that is, they make a prediction where the ball will be. The prediction is, of course, based on experience. Now, if a ball is "seen" to wobble, what actually is going on is that the prediction fails (that is, the extrapolation does not coincide with the actual trajectory of the ball), and so the ball "suddenly" is "seen" to be at a place where it "shouldn't" be. In other words: the ball does something unexpected. This observation is rationalized by the brain: you think the ball wobbles.
I don't know if this is true, of course, but it does makes sense to me.
Anyhow, logically then, experienced players would make fewer inaccurate extrapolations, so would see less often wobble. If a player has seen every possible return from an LP, he shouldn't see wobble at all anymore. So in order to produce wobble, you should do something unexpected with your LP. Chopping, chop-blocking and pushing will produce returns most opponents will be pretty familar with; but passive blocking or punching spinny balls is something in which quite a few different influences are at work simulataneously and hence are likely to result in trajectories that are difficult to predict - so wobble is to be expected.