You, along with all living things, produce subtle, ethereal, semi-visible light that glows until you die, according to a recent study.
You would be forgiven for jumping to the conclusion that this spooky luminescence is evidence that auras exist, or something similar.
But Dr Daniel Oblak, physicist at the University of Calgary and last author of the study, told BBC Science Focus that, while auras are a metaphysical, spiritual, unscientific idea, this light is not. Instead, it's called ultraweak photon emission (UPE) and is a natural product of your metabolism.
“I normally point out that UPE is a result of a biochemical process and in that sense is related to what happens in a glow-stick, which no one suspects of having an aura,” he said.
“UPE is so weak that it is not visible to the human eye and completely overwhelmed by other sources of light, unless you are in a completely dark room.”
That's not to say that shutting your curtains and turning off your lights will allow you to see your own glow. This light is between 1,000 and 1,000,000 times dimmer than the human eye can perceive.
UPE is produced when chemicals in your cells create unstable molecules known as reactive oxygen species (ROS), basically byproducts of your body’s metabolism.
When ROS levels rise, they cause other molecules to become ‘excited’, meaning they carry excess energy. It’s this energy that causes light to be emitted.
A key driver of this effect is oxidative stress – a form of cellular wear and tear caused by factors like ageing and illness. The more oxidative stress the body experiences, the more ROS it produces – and the more light it emits.
“Hence, when an organism ceases living, it stops metabolising and thus, the ultraweak photon emission ends,” he said.
To test UPE, Calgary scientists measured UPE produced by immobilised and dead mice, as well as scratched leaves.
Using specialist cameras, they observed much more UPE being emitted by the living mice, compared to their dead bodies. Meanwhile, the leaves gave off much more light where they had been damaged, compared to unscratched areas.
That's because they were experiencing more oxidative stress in scratched regions. But the dead mice did not glow, because their bodies weren’t metabolising anymore.
Oblak said that the key advantage of UPE is that it offers a non-invasive method of observing the health of living things.
“This could be used to track the condition of a tissue – for example, for use in transplants – or the level of stress an organism is subject to, such as for monitoring crop or forest health,” he said.
But this field is still full of unknowns. For instance, Oblak said: “Perhaps UPE is not just a byproduct of metabolic processes, but also serves a purpose.” Scientists just aren’t sure yet.
Read more:
- Why does light leave the position from which it is created?
- Beyond the speed of light: The strange particle that could reshape the laws of the Universe
- Ultra-bright light breakthrough could spark 'technological and scientific revolution'
About our expert
Dr Daniel Oblak is an associate professor at the University of Calgary's Department of Physics and Astronomy. He completed his PhD in quantum optics at the University of Copenhagen in 2010, but he previously studied at Aarhus University for his BSc and MSc. Now, Oblak's research interests include quantum information science, long-distance cryptography, quantum networks and quantum light-matter interfaces.
