Does the act of speculating a future event make it (more or less) likely to happen?
It depends on whether or not the event is something the speculator has a say in or not. For example, if someone speculates "I think I can make it through college if I keep trying" they have a much higher probability of actually making it through college than someone in the same exact situation who speculates "I'm just going to fail at the end of the semester anyways so I'll just give up." It doesn't mean either is going to make it through college, but if you were a gambling person and you heard each student say their forecast you would put more money on the first person making it through as opposed to the second.
On the other hand, if I speculate that it will be about 80 degrees outside tomorrow it is hard to imagine that my guess will have any extra effect whatsoever on the solar output or atmospheric currents or anything of the sort that determines the weather over here.
I was thinking of a quantum measurement analog on the macroscopic scale. Take an election for instance. If I let others know of my vote in a political race, they may be influenced to consider whom to vote for, for or against my choice, and tell yet others, etc. On the large scale this process can be nonlinear, which outcomes are often unpredictable.
Similarly, although there are logical causes involved with an economic panic, the herd or self-protective mentality sometimes snowballs from factor which, in another yet similar economic climate would be relatively benign.
Also, rather than necessarily effect nonlinearly many outcomes, one can influence just a single event far removed from our choice, in time or space. Our ancient ancestor may have decided to have a child (a quantum event?), who would effect more so directly the human race, but have little effect on other solar systems besides the few photons he or she eventually emits out into space.
I'm not sure a discontinuous quantum approach is really necessary...these situations are analyzed all the time with regular statistics. It's how they can call a state for an election for a certain candidate when they only have 5% of the vote in for example. Having people say something certainly does influence the behavior of others, TV commercials would be pointless if this wasn't true (the whole point of running a TV ad is to increase the probability that someone will find and purchase a product). Not to say that the analysis always give the right answers though. A lot of times statistical analysis is corrupted by the needs or wants of the people presenting the analysis...even in scientific papers this is true (and this is why despite the potential for statistics to be a useful predicting tool, in real life you still have to speculate on your own anyways).
If it does, the reasons are founded in psychology, not in any fundamental laws of the universe. An athlete who imagines himself winning a race might persevere longer.
But rubbing you temple in an attempt to materialize deceased loved-ones isn't going to bring anyone back to life.
There's nothing fundamentally unpredictable about nonlinear systems, they are deterministic. They just aren't subject to the relation
X_i+\delta \rightarrow X_j +gamma
where [tex]X_i[/tex] is the initial configuration, is a later configuration [tex]X_j[/tex], and [tex]\delta[/tex] and [tex]\gamma[/tex] are both small perturbations. Meaning a small perturbation in input can result in large changes in later output. This makes them difficult to preduct in practice because any error in inputs screws up the outputs. But they are predictable in principle.
As for the question of announcing who you intend to vote for, that is a question for game theory. If the goal is to pick a winning candidate (which seems to be the goal of many people who think elections are horse races) then it affects my strategy. If the goal is for the candidate I want to win, what you vote should be irrelevant to my vote. If the goal is to pick the best candidate, then your vote might affect my vote. But each of this is a different scenario.
We have the figure of speech 'self-fulfilling prophecy' for a reason. See also Oedipus Rex. Zeus vs Cronos. The story of Siddhartha Gautama (Buddha). The list goes on. The idea is common in mythology.
I don't see how you can call this a quantum measurement analog however.
Thanks for the erudition, franznietzsche. It's good for me to refine my knowledge.
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