The significance of this experiment cannot be overemphasized. The question of whether light is a particle or a wave, or both, and both at different moments or simultaneously, has been at the center of modern science since Newton's time.
The idea that one thing can be two different things at the same time runs contrary to our notion of rationality and what we consider to be basic common sense. Indeed, until the beginning of the last century, it was also what the scientific world thought.
Then along came Einstein and suggested that light was both a particle and a wave and this phenomenon has since become known as wave-particle duality.
Since then, quantum physics, has used many experiments to prove that Einstein was fundamentally correct. But, until recently it wasn't clear whether light acted separately as either a particle or a wave or was both particle and wave at the same time.
The problem was that every time scientists observed or tried to measure what was happening, the phenomenon collapsed, leaving just a standard particle. They found that you could either observe or measure the particle or the wave, but not both at the same time.
The puzzle of wave-particle duality is central to quantum physics, because the same thing appears to be true of all subatomic particles, such as electrons and quarks and even the Higgs boson particle.
However, in 2012, Live Science
reported that scientists at Bristol University, UK, carried out an experiment, which proved that light was simultaneously both particle and wave at the same time.
To do that, they used two other counter-intuitive tenets of quantum physics, that of "nonlocality", which states that one thing can be in two different places at the same time and "quantum entanglement," which says that when something happens to one entangled particle, then it will happen simultaneously to the other, even if they are at different sides of the universe.
However, despite the success of the experiment, scientists didn't have an actually observed and recorded image of light behaving simultaneously as both a wave and a particle.
In order to overcome this, the Swiss researchers employed a new experimental technique, which used electrons to capture the light’s movement.
"The experiment involves firing laser light at a microscopic metallic nanowire, causing light to travel — as a wave — back and forth along the wire. When waves traveling in opposite directions meet, they form a “standing wave” that emits light itself — as particles. By shooting a stream of electrons close to the nanowire, the researchers were able to capture an image that simultaneously demonstrates both the wave-nature and particle-nature of light."
Fabrizio Carbone, one of the authors of the study, stated in a press release
"This experiment demonstrates that, for the first time ever, we can film quantum mechanics – and its paradoxical nature – directly,"
This opens up a world of possibilities, not least in quantum computing. The MailOnline
"The technique for capturing the image could be used to help open up new areas of superfast computers that exploit the quantum states of materials."
The Swiss researchers' photograph is an historic breakthrough, which shows incontrovertibly that light is both a wave and particle at the same time.
The findings have been published in the journal Nature Communications.