One thing that everyone knows about light, but most people never even think about, is that light from two (or more) sources can pass through each other without any impact.
For example, if you take two flashlights and shine them through each other at a 90-degree angle, the end result is the same as if you shined the lights in separate directions.
This may seem unusual, but it is the result of the fact that the light photons are massless and therefore won’t interact with each other.
According to a new study, however, there are exceptions to this rule. The study found that certain types of lasers when they cross paths within a certain type of crystal, can indeed interact. In fact, one of the lasers was actually shown to cast a shadow from the other laser. Having light cast a shadow may seem counterintuitive, but it seems to be true.
In a statement about the study, Dr. Raphael Abrahao, commented:
“Laser light casting a shadow was previously thought impossible since light usually passes through other light without interacting. Our demonstration of a very counter-intuitive optical effect invites us to reconsider our notion of shadow.”
The way this works is quite complicated. The green laser has a wavelength of 532 nanometers, which changes how the crystal that it is shined through responds to certain other types of light. This includes the blue laser, which is 450 nanometers. The result is the shadow showing up.
The end result is a shadow of about 22%, which is quite significant. The study says a 22% shadow is similar to what is made by the leaves of trees.
The authors of the study went on in their statement talking about the importance of this finding, saying:
“Our understanding of shadows has developed hand-in-hand with our understanding of light and optics. Throughout…history, humans saw that shadows were cast by material objects like trees, clouds, or the Moon. This new finding could prove useful in various applications such as optical switching, devices in which light controls the presence of another light, or technologies that require precise control of light transmission, like high-power lasers.”
This is quite a finding and while additional information is needed, it sounds like it may have quite an impact on things in the future.
Who would have thought that light could cast a shadow?
If you found that story interesting, learn more about why people often wake up around 3 AM and keep doing it for life.
