Electromagnetic force has an infinite range of interaction. It is considerably stronger than the gravitational and weak forces. The photon is the key particle of exchange for electromagnetic force. The Strong Nuclear Force The strong nuclear force operates over a very short range, but it is the strongest of the forces.
Thomas Holmes and Richard Rahe are 2 now famous psychiatrists who, in 1967, put forward the idea that there may be a link to stress and physical illness.
Holmes and Rahe believe life events can be ranked in terms of the magnitude of the stress they produce. A significant but modest relationship has been found between degree of stress and physical illness. The Life Events approach is not very useful since individuals react in different ways to the same event.