Magic of any kind is a myth. There is no empirical evidence for it. In addition, there is nothing in science and our understanding of physics that would allow for such things.

Magic, as many of man's "miracles" is driven entirely by the power of belief. The mind is a tricky thing. Our beliefs work as a filter for our perceptions of reality. We often make conclusions regarding what we've perceived based on our shared understanding of what we collectively believe to be true. If we believe in magic and curses, then our minds and indeed our bodies will react in concert to that belief system. Collective social beliefs often drive and influence our personal beliefs – religion is the best example of this system of psychological influence.

Medical science capitalizes on this power by often healing with the placebo effect, giving patients sugar pills where drugs may have not been necessary. Some patients believe in the power of the "medicine" given to them and improve as a result. Clinically this is an example of the power of the mind to influence the body based on simple belief. Magic works exactly on this principle.

If you don't believe in magic, then it will have no power over you.