"But we did this." She gestures at the high-ceilinged expanse of our brownstone. (1 46-48)
Daniela and Jason both had to make big decisions before starting their family. Jason had to end his then-burgeoning research career; Daniela had to abandon her dream of becoming a first-rate artist. Both are content with these choices—for the most part, at least. But they both also sometimes regret the sacrifices they had to make.
"You killed your ambition, didn't you?"
"It died of natural causes. Of neglect." (1.540-541)
This is Jason2 talking to our hero Jason, by the way. Here, Jason2 points out how Jason had to make some big sacrifices to start his family; the implication is that he should regret those choices. But does he?
This is Daniela with an energy like the first time we met fifteen years ago, before years of life [...] transformed her into the woman who now shares my bed. (5.282)
In Jason2's universe, Jason meets a version of Daniela who made a radically different choice in her life: to dive headfirst into her art career instead of marrying Jason. This decision creates a massive domino effect, and Jason can see its impact in Daniela's disposition itself. She's practically a different person.
"Then you told me that our existence was all about choices, and that you had blown some of them, but none so badly as with me." (5.397)
Here, Daniela2 is talking about a conversation she had with Jason2 that inspired her art exhibit. As we can see, Jason2 is obsessed with the concept of choice—likely because he has always regretted his decision to put his career before his relationship with Daniela2. It's no wonder he creates the box, right?
"I think about all the choices we've made that created this moment. [...] Then I think of all the possible events that could have stopped this moment from ever happening." (6.45)
If Jason had never gone to that college party, he would never have met Daniela. Or, if he had been in a particularly bad mood, he might not have gone over to talk to her. Or, if he had got too drunk and had tripped and fallen as he was introducing himself, she might never have got with him. In any situation, there are a million tiny choices that have wide-ranging, unforeseen consequences.
"It's terrifying when you consider that every thought we have, every choice we could possibly make, branches into a new world." (6.47)
Dark Matter's conception of the multiverse is based entirely on the concept of choice. According to this book's understanding of quantum theory, no one actually makes one single choice—we actually make every available choice, and those different choices each split off into different realities. That makes our brains spin.
If there is an endless possibility of doors, then from a statistical perspective, the choice itself means everything and nothing. (8.59)
With an infinite amount of doors to choose from, Jason has a next-to-zero chance of finding his home universe by chance. It's all but impossible. Of course, we later learn that Jason's emotional state is what defines the world he enters, which gives him a lot more agency over the situation than he thinks.
"Jason was obsessed with the path not taken. He talked about it all the time." (8.594)
He's so obsessed with this concept, in fact, that he creates a hyper-advanced vehicle capable of turning back the clock on his decisions. Talk about an extreme case of FOMO: this one's darn near terminal.
Some version of me certainly kissed her in this moment.
Some version knows the answer.
But it won't be me. (11.117-119)
This is a great way of illustrating the way that choices create parallel universes in Dark Matter. While our Jason chooses to stay true to his wife and continue his search, this moment creates another Jason who makes out with Amanda and takes a different path. And then that Jason creates other Jasons when making decisions about their relationship. Holy smokes.
This man and I were the same person up until a month ago. Which means ninety-nine-point-nine percent of our history is shared. (13.457-458)
In other words, all of these Jasons have made ninety-nine-point-nine percent of the same choices in their lives. So why do they act so differently? Are they different people at their cores? Or are they more or less the same guy? What do you think?