As official interest rates on both sides of the Atlantic are pushed closer and closer to zero, central bankers are surveying what other weapons they have in their monetary arsenals that are capable of steering their flagging economies away from the twin threats of deflation and protracted depression.

Quantitative easing sounds like a course of aromatherapy by numbers. But there is nothing remotely relaxing about this in-extremis monetary remedy. This is the financial equivalent of military shock and awe, an attempt to bludgeon the whole economic system out of its downward spiral to recover some semblance of everyday normality.

The most graphic illustration of quantitative easing is forever imprinted on the bearded features of the current chairman of the US Federal Reserve, Ben Bernanke. Way back in 2002 when, in the wake of the tech bubble bursting, when the world's largest economy last confronted a genuine threat of deflation, this academic student of the Great Depression made an intriguing speech about how deflation could be avoided.

Summoning up even earlier thinking from Margaret Thatcher's economic lode-star, Milton Friedman, Bernanke pointed out that, if all else fails, governments can always print vast quantities of new money and should, if need be, take it aloft in helicopters and shower it on the troubled populace below. Money for nothing, printed round the clock, to spend on whatever you like. The wonder remedy for deflation. In public consciousness ever since, Ben Bernanke has been joined by his last resort alter ego, Helicopter Ben.

It's enough to give David Cameron a king-sized fit of the vapours. Think of what such a wholesale money drop, on top of all the billions already committed to underwriting the global banking system and injecting fiscal stimuli into ailing economies, is going to do to already groaning public borrowing, not least in Britain. Might it, however, be where we are all now heading?

Bernanke's Fed, having slashed its own benchmark interest rate to within a whisker of zero on Tuesday, is pledged to deploy "all available tools to promote the resumption of sustainable growth and to preserve price stability".

President-elect Barack Obama's advisers, having consulted economic opinion across the political spectrum in the US, are now signalling an economic recovery plan far greater than the $600bn they initially thought necessary to get America growing again. Come January, the Obama stimulus could total $1 trillion over 2009 and 2010, we are told. And that's on top of the $700bn the current Congress has already sanctioned to rescue America's banking system.

Here, the Bank of England looks set to cut interest rates again, all the way to zero if necessary. The minutes of December's meeting show that members of the Monetary Policy Committee thought seriously about a bigger cut than the one percentage point they unanimously came up with. They hesitated for fear that a deeper cut might have caused "an excessive fall in the exchange rate" and "could undermine confidence in the economy more widely".

We also know, from Governor Mervyn King's public letter to the Chancellor, that the MPC will take whatever actions are required to get gyrating expectations of UK inflation back on target, or at least within the prescribed range where no more letter writing is required.

Expect more measures, with more accompanying billions to get UK banks lending more freely again. The Governor has even hinted that outright nationalisation is not out of the question.

Even the ultra-cautious European Central Bank is talking about setting up a central clearing house for interbank lending to get money flowing more freely round the system again.

It's not quite mass helicopter drops of giveaway dollars, pounds and euros to the general public. However our monetary authorities, having virtually exhausted what they can do to cut their own benchmark interest rates, may well buy up long-term government bonds and all sorts of private asset classes at almost any price to force down interest rates elsewhere in the financial system.

Central banks may end up as the biggest banks on the planet as a result. And even if they head off deflation as a result, they risk, as they try to unwind that new reality, a return of much higher inflation thereafter. There were plenty of bankers around, before the Great Prudence and the Great Stability, who though a little bit of inflation in the system a very convenient thing, a reliable means of air-brushing away other financial sins.

We may get back there in the medium term. But right now, given the almost unprecedented and systemic nature of this crisis across the world, the challenge is to pull the global economy out of its tail-spin.

Bernanke may yet send his helicopter fleet aloft. Even if it doesn't get to that, government printing presses are going to go into overdrive, Mugabe-style, to churn out the wherewithal to ease all our fears.

The quantities don't bear thinking about. The reckoning, it seems, will just have to wait.

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