Marian, Jung's notion of synchronicity is predicated on his monistic worldview. He thought that the outer world and the psyche have one common background, denoted unus mundus, in which the psychoid archetype resides (neither material nor psychic) . In the synchronistic event, the psychoid layer manifests itself in that the event is concurrently psychic and material. But people can seldom give any good examples of synchronistic events. Your examples would be easy for a skeptic to tear to pieces. The way in which you can pick out a person from afar depends on the human visual cortex, which is the most advanced in the world. They often give examples of animals that have superior vision, in that they can see more colours, have better darkness vision, etc. But the human vision is superior, because we have a better capacity to analyze what we see. If you know that he has a red sweater, then you can instantly pick out the relevant persons, and detect the person who has the right height, etc. This goes on largely unconsciously.
Nor is your example of the president of the student body very convincing. Since he has such a public position, very many people must know his face. So he is probably likely to bump into somebody who recognizes him in his future life, in another part of the country. In case of your former husband, you probably think about him now and then. In fact, I suspect people tend to think about former partners every day, at least for a short moment. Should they bump into him/her, then they tend to view it as remarkable, since they had thought of this person today. But it's not remarkable, because they think of him/her every day. We tend to think of more peripheral people, too, especially if we lie awake at night. So it is not remarkable if we bump into them. Think of the many times that you have thought of certain people and *not* bumped into them. This is the normal state of things. So it must occur sooner or later, since we think of other people all the time, and pets we have owned. Especially if you return to the town where the person lives, then you are bound to think of him. The Vienna Opera House experience is curious, but such things are probably statistically bound to happen, perhaps once in a lifetime, or so.
So I think it is easy to dismiss your experiences as wholly natural. However, it is possible to argue that we have a sixth sense, that we can, to a degree, predict the future, and that we can sense the whereabouts of other people, etc. I think this is a more believable explanation of your experiences than the synchronistic explanation. I think that the psyche has capacities that we are unaware of, for instance, that the unconscious can catch glimpses of the future. But this has nothing to do with synchronicity.
Synchronistic events are supposed to happen when an archetype is constellated. An alternative explanation for the strange coincidences is the following. An archetype has psychic powers. Thus, it can coincide with an outer event on account of its predictive capacity. The archetype can unconsciously guide a person so that he bumps into another person, on account of the prophetical capacity of the unconscious, when an archetype is constellated. So it needn't depend on a natural force of synchronicity. It could depend on anticipation and other unconscious factors.
Jung always returned to the story of the Rainmaker
http://www.psycheandnature.com/html/rainmaker_story.html . The story goes that the Rainmaker composed himself by way of a complentative effort. Hence, nature also went back to its natural order, and it started to rain. However, a meteorologist would say that a period of draught is naturally followed by a period of precipitation. The phenomenon could also be explained by the mental capacity of the wise old rainmaker. He is a spiritual man. This means that the archetype of the self is constellated. The constellation of the archetype gives him the capacity to foretell precipitation, unconsciously. So he just goes there and awaits what he imperceptibly knows will happen.
Jung's metaphysic of an unus mundus and its concomitant principle of synchronicity remains sheer metaphysical speculation. He thinks that the psyche has the same reality status as the outer world. So he achieves this by saying that there is a psychoid reality that underlies them both. It is a form of 'neutral monism'. However, alternatively, we could view the psyche as largely independent of matter, without them having a common ground. There is no need for a neutral metaphysical layer and a principle of synchronicity to postulate that the psyche is equally real as matter.
Perhaps synchronicity needs to be subjected to more criticism in the Jungian community. It seems that most Jungians simply swallow it, uncritically.
Mats Winther