The debate about whether light consists of waves or particles dates back to the 17th century. Early in the 20th century, Albert Einstein, Niels Bohr, and others exploring the world of quantum mechanics said light behaves as both waves and particles. Later experiments clearly showed this "wave-particle duality," but they were never able to show light as both waves and particles at the same time.
Now, in a triumph of science and engineering at scales measured in nanometers and femtoseconds, international researchers have shown light acting as waves and particles simultaneously and continuously, and they have even produced photographic images of it. The scientists are from École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland, Trinity College in Connecticut, and Lawrence Livermore National Laboratory in California.