Exactly one hundred years ago, the world was plunged into what we now call World War I by accident. No one wanted the war, no one foresaw it happening, but it did and even today the world weeps for the flower of youth of all Europe who died in it.

Today, 100 years later, Europe is once again being involved in an equally tragic series of events with completely unpredictable results.

For all the reassurance that has been dripping from the lips of Europe's political leaders, a Grexit - the exit by Greece from the single currency - can still happen.

Today, the greatest risk is that it happens not by design but by accident, through some possible miscalculation or such accident.

Europe is not planning for a Grexit. On the contrary, reports these past days have said that Commission president Juncker has forbidden his staff from working on a Plan B, fearful, with reason, that if such a plan were to be drafted, it would soon leak and plunge the continent and the world in a crisis.

There is no doubt that a Grexit will plunge Greece into chaos - banks closed, ATMs not working, people having to live without any form of money.

What may come later is even worse: if the country resurrects the drachma, it will inevitably plunge in exchange value the minute it is issued, hence everything will become costlier and Greek living standards, such as they are, will plunge and plunge again.

It is frequently said that due to the firewalls built in the system over the past few years, the rest of Europe can take a Grexit without extensive damage.

This is not true. Apart from the immense harm done to the very idea of a single currency (especially that there can be no exit from it), banks and other financial institutions, let alone the ECB are still owed money by Greece and this, with a Grexit, becomes unrealizable.

The past months, ever since Syriza won the election, have been wasted months. Elected on a campaign promise to do away with the austerity and diktats from the troika (IMF, ECB, Commission) the new government has brutally stopped the steps that were being taken by its predecessor and which, while very hard, had begun to lead Greece away from the brink. On the contrary, hardened by Marxist theory and a Communist core, the new government reversed decisions that had already been taken, such as blocking half-concluded privatization, and the reinstatement of people whose employment had been terminated.

Above all, it turned every contact and negotiation with the troika into a battle and a public showdown.

Greece has now been rolling from crisis to crisis for several months, while negotiations with Europe to unlock a €7.2 billion tranche of bailout cash are not progressing at a very fast pace. Little compromise has been made on big issues like labour market regulation, pensions, and privatisation.

Default seems more and more likely. But the big question is: When will Greece actually run out of cash?

First, people worried about the April 9 IMF payment, but Greece made that. Then people worried about April 20, and HSBC mentioned that May 12 could be the crunch point, but many think that the government will manage that payment now that it's draining more money from local governments.

One survey of 29 economists put the chance of debt default at 40% and Grexit at 30%, but most thought that one would not trigger the other.

For some economists, potentially the best option would be for Greece to pursue a "managed default".

That could mean more relaxed and longer terms on servicing the debt on its eurozone loans.

But it could also mean Greece remaining in the eurozone with strict capital controls to stop money from flooding out of Greece.

One idea, reportedly under consideration in Germany, would be for the ECB to continue funding Greek banks while considering them in default, in return for strict guarantees for structural reform.

Now, at the eleventh hour and 55 minutes, the Greek prime minister made a sly move earlier this week - he sidelined his flamboyant finance minister and replaced his team with more EU-acceptable persons. And, maybe in a move to placate his hardline Left, he spoke of the possibility of a referendum.

Will this be enough to avert the disaster? Or will rather an accident, a miscalculation, blow apart this very delicate situation?