See also: The Force
For most of the history of the Republic , The Jedi were looked upon as defenders and protectors of justice. By their example, belief in The Force was accepted if not always understood. Most beings could not perceive The Force directly; they could only see it manifest in those attuned to it, such as The Jedi . At times over the years, The Dark Side came to the forefront, such as during the ancient Sith Wars, but in general the champions of the light side helped keep the galactic peace.
During the Rise of the Empire era, The Force is a powerful component of everyday life. The Jedi are visible, active proponents of The Force. Regardless of what an individual may believe about The Force, it's hard to deny the power demonstrated by The Jedi. As the Clone Wars rage across the galaxy, Jedi are seen at the forefront of battles, and The Force impacts the lives of soldiers and citizens alike.
Later, in the wake of the destruction of The Jedi Order and the rise of the Empire, The Force comes to being looked upon as an arcane religion practiced by misguided fools. The Empire outlaws The Jedi and attempts to stamp out anyone who demonstrates an affinity for The Force. Propaganda and politics keep the local systems in line and succeed in driving Force-users underground, where they live in fear and obscurity.
If your campaign is set in the Rebellion era (Around the time of Episodes IV-VI), The Force has faded from common knowledge. Those who can manipulate The Force keep their skills hidden to avoid the notice of the Empire. Even members of the Imperial hierarchy, despite the presence of Darth Vader, consider the Force to be outdated and insignificant to the military might of the Empire. In many ways, that's just how the Emperor wants it. Even the Emperor, one of the most powerful Force-users in the galaxy, keeps his Force abilities secret from the general public and most of his subordinates. The few Force-users that exist during this period are either hiding from the Empire, working for the Empire, or trying to ignore the presence of the Force. The Rebel Alliance has begun to use the Force as a rallying cry, adopting the Jedi salutation, "May the Force be with you," as its own. Because of this, the few Force-sensitive beings that can actually use the Force begin to reach out to the Alliance. And, of course, Luke Skywalker begins his training during this time.
If your campaign is set in The New Jedi Order era, The Force has regained a place in everyday society and a new fellowship of Jedi has come to prominence under the tutelage of Luke Skywalker. Many beings in the New Republic, however, harbor varying degrees of mistrust and fear toward Force-users. these negative feelings are due, in part, to the actions of a few rogue Jedi who have taken the law into their own hands and have begun to rebel against Luke Skywalker's leadership. The memories of a host of darksiders that plagued the galaxy since the time of Darth Vader and the Emperor add fuel to the fire of fear, and the political machinations of members of the Republic Council have begun to fan these flames. Force-users of this period, then, are finding that acceptance of the Force among the general population may turn into a bad thing- at least as far as they are concerned. Tensions are already high, as this era is marked by the invasion of the Yuuzhan Vong.
Additional The Force through the Ages Edit
Reference Book: Star Wars Saga Edition Jedi Academy Training Manual
See also: Power of the Force
Not every Force Power or Force Talent is well known in all eras. Knowledge is gained and lost over time, and techniques that are common during The Great Sith War are all but forgotten by the time of The Clone Wars. Though all Force Powers and Force Talents in the Core Rulebook are assumed to be applicable in all eras, some of the powers found in the various Reference Books may be restricted by era.
Gamemasters should feel free to rule that some Force-related abilities just cannot be found in some eras. In particular, Force Powers are likely to be extremely restricted during The Dark Times and The Rebellion Era, as they represent a time when Emperor Palpatine tightly controls knowledge of The Force and The Jedi are all but extinct. In eras where The Jedi are commonplace, a wider variety of techniques may be available for use, but even then much knowledge has been lost, or is yet to be discovered.