In science, they call it a "phase transition," the process in which something is suddenly and dramatically altered. At 32 degrees, for example, ice remains ice. But at 33 degrees, ice is transformed from a stable solid to a free-flowing liquid. That's a phase transition.

Apparently, $4 gasoline is a lot like that; it too is the critical point at which attitudes long frozen in place finally begin to melt and flow freely. Americans start driving less, Detroit starts making smaller cars and — wonder of wonders — Gov. Sonny Perdue calls a press conference to publicly embrace mass transit, saying that he "fully supports" a proposed commuter rail line linking Atlanta with Lovejoy on through to Griffin, with other lines coming on later.

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The goal, Perdue said, is "providing Georgia commuters with real alternatives."

I know — it's hard to believe. But I was there in the crowd when the governor uttered those words.

He went on to call for "innovative and progressive decision-makers," and even admitted that Georgia will need "additional resources" to solve its transportation crisis ("t-a-x" being a four-letter word, at least in Perdue's dictionary).

However, you could tell that the governor wasn't entirely comfortable with his new persona. While he adopted position after position that he had long rejected, he did so by recasting them in GOP-friendly terminology. The state of Georgia won't be "spending" more money to meet its critical transportation needs, it will be "investing" that money "to bring dividends for a long time." And instead of drafting a new, more progressive transportation policy for Georgia, Transportation Commissioner Gena Abraham and other state officials will "develop a business case" for transportation.

All that's fine. If calling it a "business case" and "investment" allows the governor to back a plan that reduces congestion, cleans the air, gets commerce moving and offers commuters an alternative to the gasoline-powered internal combustion engine, he can call it Ralph for all I care.

Gas at four bucks a gallon has also done something else magical: In Perdue's mind, at least, it has driven a phase transition at the state Department of Transportation, transforming it from a crippled agency to a bureaucracy ready to build "a world-class transportation system."

Just a couple of months ago, you might recall, the state DOT was in such disarray that Perdue cited the agency as his chief reason for opposing a plan to boost transportation spending — oops, investment — in the metro region. The department just wasn't ready to handle it, he explained.

Yet by last week Perdue had changed his tune. In his almost two decades in state government, he said, "I believe that this is the best state transportation board I have had the privilege to work with."

Again, the board didn't suddenly improve. The governor's sudden switch of position has been forced by pressure from voters, business groups, legislators and local officials outraged by the stubborn refusal of state leadership to take the transportation problems of metro Atlanta seriously. What we saw last week was proof that the message had begun to get through.

Little of what the governor endorsed was new; federal money for the Lovejoy line has been available since the administration of Gov. Roy Barnes, for example, but the project has gone nowhere, in large part because of skepticism from Perdue.

Over the years, the governor repeatedly opposed kicking in state matching funds for the project on grounds that rail operations would be subsidized by taxpayers.

Last week, he again mentioned that fare-box revenues would not be enough to cover operations for the Atlanta-Griffin line and public subsidies would be required.

"But we also know that roads are subsidized too, that they don't pay their full fare," the governor said.

Like I said, I might not believe it if I hadn't heard it myself. Now, we'll see if hopeful words become action and then progress.

• Jay Bookman is deputy editorial page editor. His column runs Monday and Thursday.