MARY KALDOR: "It’s all about, I think, a failure of representation, a feeling that the political class is one class, 'We can’t influence them, it’s outrageous that they’re suddenly saying that we have to pay for what the banks did.' And I think that there’s a similar feeling of outrage in the Arab world. So I think there are very many similarities between what’s happening in Europe and what’s happening in the Arab world."

In Spain, protesters occupied the Puerta del Sol square in central Madrid, copying the earlier protests in Cairo's Tahrir Square.

In London, British protesters demonstrated earlier this year against their government's cost-cutting measures. Owen Tudor is international secretary for the Trades Union Congress in Britain.

OWEN TUDOR: "I think there are clear differences for what’s going on in different countries. We’re talking about democracies in Europe, dictatorships across much of North Africa. But many of the causes of what’s happened have been very similar. It’s about the economic crisis."

Israel recently had some of its largest demonstrations ever. Israelis have criticized housing costs, wages, taxes and rising prices for food and fuel. Prime Minister Benjamin Netanyahu is promising economic reforms but has failed to satisfy social activists.

Some observers see the Arab Spring coming to a halt in Libya and Syria. But Professor Kaldor says the protests have already changed the Arab world.