A balance exists in the universe. Many call it the balance between good and evil but from a scientific perspective it is the +/- positive and negative balance that is present in our universe.
Many believe in karma which is the understanding that those who project positive energy and do good deeds for others, will naturally have that positive energy returned to them. On the other hand, those who are hateful and unfair will eventually receive justice based on the negative energy they draw. Much like the planets, what goes around will eventually come around again.
Quantum theory, spirituality and most religions have an understanding that everything in the universe is connected. Since human beings are a magnetic field and project energy, we essentially alter the charges of invisible particles around us. This chain reaction of energy we send out can adversely affect others.
Have you ever wished something negative upon someone only to have it come true? Projecting negative energy towards somebody will essentially change what happens inside their mind and body whether they are conscious of your negative intentions or not. On the same level, positive attitudes in general seem to bring positive experiences. Many say this is just an illusion but quantum theory again, states that reality is simply an illusion of our minds. Without a balance between positive and negative, nothing could theoretically exist. Good cannot exist without bad just as hot could never exist without cold to compare it to. Those who think "its all good" are just as wrong as those who think nothing good is possible. The fact of the matter is, its a 50% split between both positive and negative that must exist in every factor. Projecting energy by thought (which begins as a small electrical signal in our brain) can easily manifest into a physical reaction as it changes the charge of particles around us. This energy can be transmitted and absorbed by other humans on a level that we are only beginning to understand. Perhaps scientists should look to voodoo for answers.
The following video explains the concept behind our thoughts being able to affect matter and those around us: