What does Neil McCauley mean with "I'm a needle starting at zero, going the other way, a double blank."?

I think “a needle starling at zero, going the other way.” Refers to an analogue thermometer which somehow resembles his life getting colder and colder below zero, freezing even. and since the movie is called HEAT, he finds Eady as someone who gives him warmth. “Double blank” is just something you say to exaggerate that you really got nothing left at all.

According to Michael Mann:

DEADLINE: So you have the equally competent cop and robber who think they are in control, but can’t control the circumstances of people swirling around them…

MANN: There’s Neil, living a catechism of non-attachment. That is the smart way to live your life when you’re living outside the law and you come from circumstances of alienation and loneliness. You maintain your loneliness, you maintain your alienation, except for your bond to your partners, and you don’t get attached. You don’t have anything in your life you can’t walk from in 30 seconds flat. Because you’ll make one phone call, two years from now in Brazil, and they’ll be tracking that call and if you have sentiment for that woman, they’ll locate you. So you don’t get attached. You leave that for after you’ve scored and take off.

Then he described his life to Eady as a needle starting at zero and going the other way, a double blank and then you come along. So he abandons it and there’s an initial rush of living an emotional life spontaneously, which he’s not supposed to do. In making that happen, he’s abandoning navigation. So then he’s susceptible to being seduced with vengeance to go get Waingro, which is his undoing.

IMHO trying to parse it too closely is missing out on the odd poetry of it. Technically a needle cannot go below zero (although there are meters where staying below zero is a good thing, e.g. decibel meters), and that is in a way his point: it's not like he hasn't had the opportunity or that he wasn't that interested in the past, he actively avoided it.

Interesting question. Had never heard the expressions before.

I agree with JoJo, “Double blank” is just something you say to exaggerate that you really got nothing left at all."

Like double-zeroes. But thought I'd share the results of the hunt anyway.

1. Wiktionary - "(dominoes) A domino without points on both of its divisions. - the double blank."

2. In a book called, Without Prejudice (Israel Zangwill, 1899) is the following humorous excerpt:

p. 171 (1899 English spelling)

1. Society for Providing New Oaths

The present currency is badly worn and was always nasty. Swear-words are a necessity. They are the safety-valves of the soul. Why not have them nice and innocent—the kind of oath a girl can use to her mother?

It is unfair men should monopolise the bad language. I wonder the Women’s Rights women have not sworn about it. I have already suggested that Wellington’s “twopenny damn” be replaced by “I don’t care a double-blank domino.” This gives a compound or two-penny sensation of the unspeakable, combined with absolute innocuity, like a vegetarian chop or a temperance champagne. A milder form (the penny plain) would be “a blank cheque.” The society ought to offer prizes for the best suggestions.”

3. As a chapter in a book titled, Dominos (Jack Aqueros 1993): Double Blank: The Dead Man's Box.

For the needle part, someone on another site guessed that he didn't 'go the same way as other people'. Which made me think of electrical current. "If the direction of the current is reversed, the compass needle will move in the opposite direction because the polarity of the magnetic field has reversed." - He's 'wired differently' - until something begins to change.