A neutral country is a state that is neutral towards belligerents in a specific war or holds itself as permanently neutral in all future conflicts (including avoiding entering into military alliances such as NATO). As a type of non-combatant status, nationals of neutral countries enjoy protection under the law of war from belligerent actions to a greater extent than other non-combatants such as enemy civilians and prisoners of war.
Different countries interpret their neutrality differently: some, such as Costa Rica, have demilitarized, while Switzerland holds to "armed neutrality" to deter aggression with a sizeable military while barring itself from foreign deployment. However, not all neutral countries avoid any foreign deployment or alliances, as Austria, Ireland, Finland and Sweden have active UN peacekeeping forces and a political alliance within the European Union. The traditional Swedish policy is not to participate in military alliances, with the intention of staying neutral in the case of war. Immediately before World War II, the Nordic countries stated their neutrality, but Sweden changed its position to that of non-belligerent at the start of the Winter War.
There have been considerable changes to the interpretation of neutral conduct over the past centuries. During the Cold War another European country, Yugoslavia, claimed military and ideological neutrality, and that is continued by its successor, Serbia.
Does someone can explain that?
The transition frequency v of atoms exposed to the
lattice electric field of E is described as,
hv = hv^(0)-(1/4) alpha(e,w)E^2-(1/64) gama(e,w)E^4
where v^(0) is the transition frequency between the unperturbed atomic states, alpha(e,w) and gama(e,w) are...