We often say that when a person dies, the light leaves eyes. But it turns out that all living things, including humans, emit a literal light that is extinguished after death.
The study was published in Journal of Physics and Chemistry,,,,, It was found that life organisms shine faintly throughout their lives due to the energy released by metabolism and cellular processes. Monitoring this weak signal can one day help scientists track injuries and diseases.
As cells consume energy, mitochondria release a small amount of reactive oxygen species (ROS) as a by-product. These ROS react with molecules including proteins, lipids, and fluorophores, emitting some sparse photons. However, this light is a phenomenon called Ultraweak Photon emission (UPE) compared to ambient light sources, which is indeed weak and really difficult to image, as its name suggests. It was observed in cells belonging to plants, animals and humans, but never happened throughout life or death.
To capture this ghostly glow, lead author Daniel Oblak is an associate professor at the University of Calgary, whose team uses a hypersensitive digital imaging system. They placed mice in dark temperature controlled boxes and imaged with two hours of exposure. When they image a living mouse, they see photons rising up on the mouse's body and have hot spots on its organs, head and claws. However, dead mice showed widespread decline in UPE, indicating that their light had been eliminated.
“While living mice emit powerful UPE, which may indicate sustained biological processes and cellular activity, UPE emissions from the dead have almost been extinguished,” the authors wrote in the paper.
Not only animals – plants also emit an extraordinary light. The researchers analyzed the ups in an umbrella tree and found that the intensity of the luminescence increased when the plant was injured or exposed to high temperatures. Chemical modifications, especially the application of anesthetized benzos, also increase the intensity of this light.
Because light is associated with metabolic activity, the amount of light emitted by the tissue may increase. By viewing tissue that produces too much or too little light, doctors can non-invasively monitor the health of tissue. The authors say researchers can also monitor health and plant growth under different environmental conditions.
UPE may be a “promising tool to promote our understanding of plant biology and biomedical research at a basic level,” the authors wrote.
