The second half of their season starts tonight, and the Patriots are now operating in two parallel universes, whether they want to admit it or not.

They are trying to win another Super Bowl, the obvious goal.

And they are playing for immortality.

That is what happens when you’re 9-0 and most of your games have been a mismatch. This is what happens when you clearly are the best team in the NFL, and each week seems to bring more confirmation. This is what happens when you already have gotten the attention of the 1972 Dolphins, who cling to the memory of their undefeated season the way most of us cling to the memory of childhood.

This is the reality that now surrounds the Pats, this sense that they are now playing against the ’72 Dolphins as much as they’re playing against the rest of their schedule.

And it’s one that’s only heightened every time one of them talks about the Patriots, whether it’s Don Shula, who threw out the theory a couple of weeks ago that whatever the Pats accomplish will be tainted because of videogate, or former players who say they are openly rooting against the Patriots.

This is the new reality, and it’s already what’s talked about, whether it’s on talk shows or around the water cooler. Can they run the table? Can they go undefeated? Can they achieve their slice of football immortality, just like the ’72 Dolphins have? Rest assured, no one’s talking about tonight’s game against the Bills.

Fair or not, that’s the new reality, too.

Bill Belichick spends each week talking about the upcoming opponent as if they’re like two downs away from Canton, and we yawn. The players parrot the party line about how each week is a new challenge and our eyes glaze over. The weekly mantra is they play one game at a time and we write down the words, then wonder which of the remaining games are the dangerous ones, the potholes in the road, the potential dream slayers.

This team has already raised the bar so high that we no longer care about the Bills, or the Jets, or really any of them, save for the Steelers, who come in here on December 9th, or maybe on the road against Baltimore the Monday night before that.

The rest of the games?

Just don’t have Tom Brady get hurt, right?

This team has raised the bar so high that anything less than the Super Bowl will be seen as a major disappointment, as if everything is positioned for the Super Bowl to be a coronation, the home field in the playoffs, the fact they beat the Colts in Indianapolis, the fact they have become the odds-on favorite to be the last team standing when this NFL season finally ends in Arizona in early February.

Which means it’s become about immortality.

This is what this team is now chasing, and it’s heady stuff. For the dirty little secret of the Super Bowl is that someone wins every year, teams that eventually disappear into the mists of history, remembered by their fans and usually forgotten by everyone else. To go undefeated is another realm. It takes a team into history.

Even now, so many years later, we remember the ’72 Dolphins in ways that so many great teams have become blurry, lost in the years. That’s the team commemorated in the Pro Football Hall of Fame in an exhibit called “The Anatomy of a Great Season.” That’s the team whose memory gets resurrected every time someone gets off to a great start.

And it doesn’t matter that that Dolphin team won two games by two points, and another by one in that dream season. It doesn’t matter that it won one playoff game by just four points, and the Super Bowl by just a touchdown. It doesn’t matter that most of their games that year were very competitive. It doesn’t matter that they were nowhere near as dominating as the Patriots have been this season.

No one remembers that, and ultimately it’s irrelevant.

What’s remembered is that they won all their games.

What’s remembered is they now stake their claim to being the best team in NFL history. Are they? Who knows. But their undefeated status is remarkable cachet. Its gives them a trump card no one else has, makes them unique.

That is what the Pats now chase, regardless of how much they underplay it.

But we all know how much of an NFL historian Belichick is, how much he respects the league’s past. And we suspect how much this would mean to him, especially this year, how much validation this would be, not only for his place in NFL history, but for the public embarrassment he went through with the videogate mess.

We all know how going undefeated would cement this team’s place in NFL history, in ways the three Patriot teams that won the Super Bowl never will be, even if they established their credentials as a dynasty. We all know how unique an opportunity this is, how good you have to be, and fortunate, too. The fact no one’s done it since 1972 is testimony to that.

So here are the Pats, as they start the second half of their season, chasing another Super Bowl and history, too.

For the ’72 Dolphins have become the new opponent, right there on the schedule with the Bills and the Eagles and the Jets and everyone else left on their schedule. The ’72 Dolphins, and the immortality they have.

The immortality this Patriots team now chases.

breynold@projo.com