editorial A year to remember 2015 marks the 150th anniversary of Maxwell’s formulation of his theory of electromagnetism and a year-long celebration of the importance of optics. Happy New Year. This month marks the the Italian Guglielmo Marconi that things start of the International Year of Light and really started to change. Light-based Technologies (IYL 2015) — an Leaping ahead 100 years, Allen Taflove initiative driven by UNESCO (United at Northwestern University in the USA Nations Educational, Scientific and Cultural pioneered the development of efficient Organization) to raise awareness of the numerical schemes for solving Maxwell’s importance of optical technologies to equations in the 1970s and 80s, in particular, citizens of the world. The aim is to promote the so-called finite-difference time-domain improved public and political understanding (FTDT) technique. We interview Taflove of the benefits of photonics in the modern on page 5. The creation of practical and world, and the solutions it provides in the computationally-efficient schemes for areas of energy, communications, healthcare, dealing with Maxwell’s equations has proved agriculture and education. to be vital for the design and simulation In many ways, a perfect illustration has of a wide range of devices spanning from recently been serendipitously provided in the radio wave radar to microwave components form of the 2014 Nobel Prizes, announced and optoelectronic and photonic devices. in October. The 2014 Nobel Prize in Physics Whereas today, advances in computing and the 2014 Nobel Prize in Chemistry were power mean that such simulations can often awarded to the inventors of two exciting be run on personal computers, Taflove and impactful developments in photonics: comments that during the early days he the realization of the blue GaN LED, which IYL2015 heavily relied on supercomputers and that underpins a revolution in highly-efficient this generated considerable scepticism solid-state white LED lighting, and the of the formulation of Maxwell’s equations from critics. development of super-resolution microscopy, and their present day utilization. Taking another step forward in time, the which has profound implications for the On page 2, Basil Mahon — the idea of producing artificially-engineered study of biological processes. For detailed author of several books about key metamaterials with custom-designed values coverage of these individual achievements figures that played pivotal roles in the of permittivity and permeability (and thus please refer to the articles in our December development of our understanding refractive index) that cannot be found in issue (Nature Photon. 8, 884–886; 2014, and of electromagnetism, including natural materials created new opportunities Nature Photon. 8, 887–888; 2014). Michael Faraday, James Clerk Maxwell and for manipulating Maxwell’s equations. As for the formal plans for IYL 2015, Oliver Heaviside — provides a fascinating In 2006, John Pendry and Ulf Leonhardt it will officially kick off with an opening historical commentary that explains how published a new way of looking at Maxwell’s ceremony on 19–20 January in Paris, the equations came about in the middle equations called ‘transformation optics’. They France, followed by a series of educational of the nineteenth century and how they realized that the equations’ invariance to events around the globe that will celebrate were received at the time. Interestingly, coordinate transformation offered a means optics and its connection to society with a many people don’t realize that it was the of designing all kinds of optical devices with host of visual and fun demonstrations. A English mathematician Oliver Heaviside interesting and unusual functionality such full calendar of events and a programme who actually formulated the equations in as invisibility cloaks, energy collectors and of activities can be found on the IYL 2015 their current, succinct and famous form of perfect lenses. On page 15, Huanyang Chen website (www.light2015.org). four short expressions involving vector field and Lin Xu of Soochow University in China Alongside a long list of partners and calculus. Maxwell’s initial formulation was review the principles and capabilities of sponsors that includes notable scientific far more complex, involving 20 equations transformation optics and the possibilities societies, universities and companies, and 20 variables. Many also don’t realize that it creates. Indeed, the combination Nature Photonics is pleased to be a gold that Maxwell was residing at King’s College of transformation optics with advances associate of the initiative and will be London (which has been running a series in nanoscale fabrication technology and contributing by publishing a series of of anniversary lectures) when he penned the ability to actually make artificially- dedicated articles throughout the year. his equations. engineered metamaterials has given a There seems to be no better way to Unsurprisingly, the significance of the new lease of life to Maxwell’s equations start than with a celebration of the 150th equations and their hypothetical waves was and photonic design. It is now possible to anniversary of James Clerk Maxwell’s not truly appreciated at the time. It was actually create materials that can manipulate equations that predicted the existence only many years later when electromagnetic light and other forms of electromagnetic of electromagnetic waves and underpin waves, in the form of radio waves, where radiation in ways that would have probably the behaviour of light. This issue of experimentally proven to exist by the astonished Maxwell. ❐ Nature Photonics brings together a collection German scientist Heinrich Hertz and later of articles that provide the historical context investigated for communication purposes by Corrected after print: 6 January 2015 NATURE PHOTONICS | VOL 9 | JANUARY 2015 | www.nature.com/naturephotonics 1 © 2015 Macmillan Publishers Limited. All rights reserved Correction In the Editorial ‘A year to remember’ (Nature Photonics 9, 1; 2015), the page number of the Review Article by Huanyang Chen and Lin Xu was incorrect and should have read 15. This has now been corrected in the online versions after print 6 January 2015. © 2015 Macmillan Publishers Limited. All rights reserved.