NEW YORK (CNN/Money) - If the U.S. economy were the starship Enterprise, then right about now would be the time when Scotty, the ship's chief engineer, would complain to Captain Kirk -- Alan Greenspan, in this metaphor -- that the ship was being pushed too hard.

But Federal Reserve Chairman Greenspan and his crew have made it clear lately that they're keeping interest rates super low and the economy at Warp Factor 9 for some time -- perhaps until the far-off year 2005.

To be sure, plenty of observers are already playing the role of the nervous Scotty in the old TV series "Star Trek," and they have a compelling case.

Gross domestic product (GDP), the broadest measure of the economy, grew at an 8.2-percent annual rate in the third quarter, the fastest quarterly pace in nearly 20 years, and most economists believe it will grow at about a 4 percent rate in 2004, the strongest full-year pace since the late 1990s.

Meanwhile, gold and raw material prices have surged, the dollar has weakened, and the yield gap between inflation-protected Treasury bonds and normal Treasurys is widening – all leading indicators of inflation.

Some worry that, by waiting too long to raise interest rates and leaving the economy running at top speed, the Fed is creating runaway inflation -- either in consumer prices or by inflating a dangerous bubble in stocks or home prices -- that will cripple the economy.

"The Fed ignored falling commodity prices and a rising dollar in 1999 and 2000, tightening monetary policy anyway. The result was a recession and deflation," said Brian Wesbury, the conservative chief economist at Griffin Kubik Stephens & Thompson in Chicago. "This time the Fed is making the same mistake, but in the opposite direction. The result will be rising inflationary pressures and bond yields."

Even though their key federal funds rate is at 1 percent -- the lowest level in 40 years and considered by many to be an unsustainable "emergency" level -- Fed policy makers haven't exactly been laying the groundwork for an impending rate hike.

In late December, Richmond Fed President Alfred Broaddus, a voting member of the Fed's policy committee and a noted inflation hawk, said inflation as measured by the Consumer Price Index was too low by at least 0.5 percentage point.

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And on Saturday, influential Fed Governor Ben Bernanke, another voting policy committee member, said current Fed policy was "appropriate, despite its historically unusual character."

Bernanke took most of the worriers' arguments and dismissed them, one by one. Higher commodity prices? They're just a result of a stronger global economy, and they don't usually translate into higher consumer prices.

A stronger dollar? No sweat -- while the dollar has plunged against the euro, it's only fallen about 12 percent against most of the country's major trading partners.

Higher gold prices? That's more of a measure of the unrest in the world -- gold is considered a "safe-haven" investment -- than any fear that the dollar will plunge into an inflationary death spiral.

And key measures of consumer price inflation have lost steam in recent months. The Fed's favorite gauge, the Commerce Department's core personal consumption expenditure deflator, grew at its slowest pace in history in the 12 months ended in November.

Labor-market weakness is the prime culprit, according to Bernanke and other economists. Technology-driven productivity gains have allowed companies to squeeze more work out of fewer workers, and many firms are sending work overseas, where labor costs are much cheaper.

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As a result, the economy has been able to grow like gangbusters without adding many more jobs, while keeping wage and salary growth -- by far the biggest component of consumer price inflation -- in check.

Goldman Sachs senior economist Bill Dudley said in a research note last week that the economy could grow at a 5-percent pace for a year before using up all its excess labor and production capacity. Until that happens, he said inflation will stay low and the Fed will stay on hold -- meaning no rate hike until 2005, a view shared by many economists.

"There's no reason for the Fed to raise rates," said Scott Brown, chief economist at Raymond James & Associates. "With inflation very low, interest rates should be low as well."

But the fed funds futures market, in which traders bet on Fed policy moves, disagrees, predicting there's a decent chance the Fed will start raising rates at its scheduled May meeting.

Some economists believe the Fed will not wait for higher inflation to raise rates, but will only look for evidence the labor market has really and truly healed -- and that could come rather quickly, according to some forecasts.

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"We haven't seen big gains in jobs yet, so Greenspan can't be completely confident this expansion will be self-reinforcing," said Anthony Crescenzi, bond market strategist at Miller Tabak & Co. "But I believe a blowout employment report is on the near-term horizon, and that will set the conditions for a change in interest rates."

Another factor that can't be ignored in the outlook for Fed policy is November's presidential election. Some observers worry the Fed is keeping rates super-low to keep the economy on steroids and assure that President Bush gets a second term.

Still, most economists believe the central bank will not hesitate to raise rates if necessary.

"They'd just as soon sit on the sidelines in an election year, but they will do what they have to do, and they have moved in other election seasons," said former Fed economist Wayne Ayers, now chief economist at Fleet Boston Financial.