It’s a brave new world for Californians headed to vote in the state’s primary today.

Among the changes: There are no party primaries, they can send two members of the same political party on to the general election and many people will be voting in revamped congressional districts crafted by a panel of fellow citizens.

Austrian born actor and former Governor of California Arnold Schwarzenegger conducts a local music band upon his arrival in Guessing in the province of Burgenland, Austria, on Sunday, Jan. 22, 2012. (AP Photo/Ronald Zak)

“California will make history tomorrow,” Schwarzenegger wrote. “We will see our open primary system and new citizen-drawn districts in action for the first time. There is nothing else like it and I know we are starting yet another national trend.”

But just how does it work? And how different is it?

California’s congressional delegation is notoriously entrenched, and in fact, just one of the state’s 53 districts switched between parties over the last decade (and it only did so once).

Under the new system, there should be considerably more party swapping. Why?

First, the redistricting map drawn by the citizens commission totally revamped the gerrymandered congressional map, leaving many incumbents drawn into districts with other incumbents. Others found themselves in much more competitive districts or with no seat at all to run in.

The result is that upwards of a dozen seats in California will be genuine tossups this fall.

The way in which those winners will be chosen will be different too.

California has adopted a “top-two” primary system – already used by Washington state – to select two candidates for the November general election. All candidates today will run on the same primary ballot, meaning some districts will see two Republicans or two Democrats move on to the general election rather than one from each party.

The reason that’s significant is that those races could now be decided by voters from the party that doesn’t have a nominee. So if Reps. Brad Sherman (D-Calif.) and Howard Berman (D-Calif.) face off in November, as is expected, Republicans in their district will be forced to vote for one of them and could swing the election. (Cue intrigue.)

The idea for both the new nominating system and the citizen-drawn redistricting map is to create more competitive districts and help elect more moderate legislators to Congress.

Of course, as with all change, not everyone likes this new system.

Besides the politicians who, of course, do not want to have to run for their political lives in more competitive districts, independents say that top-two system works against them by only allowing two candidates through to the general election. There is no avenue for an independent to petition him or herself on to the general election ballot, they argue.

In addition, extremely crowded primaries can lead to odd general election matchups as candidates with loyal — albeit it small — following can edge into a second place finish. The most obvious example of that is in the California Senate race where Orly Taitz, a leader of the so-called “birther” movement, could wind up facing off against Sen. Dianne Feinstein (D) in November.

There were also critics of the citizen’s redistricting process, and some reports indicated that the Democratic Party, in particular, subverted the process in order to get the map drawn in its favor. (Creating a truly independent process for redistricting has proven very difficult, though California’s attempt has earned praise.)

Whatever the case, today begins an historic election cycle in California – one in which change in the largest state in the country is a foregone conclusion. It just remains to be seen what kind of change will take root.