Dear readers, collaborators and friends,
We wish you a merry Christmas and with a bit of advance, a happy new year !
As this 2017 year has started in a somehow troubled and strange manner for the world, we hope that things will stabilize in the coming months. And as all the actions toward a more peaceful world desserve to be highlighted, we wanted to bring to the fore this nice editorial from Pierre Meystre in Physical Review Letters.