this post was submitted on 19 May 2025
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Interesting. I wonder if humans can subconsciously pick up on it. Supposedly humans can often subconsciously detect when someone else is in the room through tiny vibrations in the air. There is definitely some visual quality that separates a dead person from a live one, but I personally think it's something with the pupils. It'd be cool if it was miniscule traces of light, though.
The paper itself says "The phenomenon of biological ultraweak photon emission (UPE), that is, extremely low-intensity emission (10–103 photons cm–2 s–1) in the spectral range of 200–1000 nm, has been observed in all living systems that have been examined." Human vision falls within that spectral range, but the brightness is several orders magnitude too faint to see with the naked eye, even in absolute darkness.
It's the stillness. It's there even when the pupils aren't visible, although there are some changes with the eyes after death (tache noir comes to mind).
I've noticed when pets die that they appear dim and grey afterwards. Not just their skin and eyes, but also their hair. It's an immediate change. I've always thought of it as the light going out of them.
Animals are very rarely completely still. Even the motion of breathing or their heartbeat is enough to create very slight motions. This causes their fur to subtly move and shimmer. Our brain evolved to spot things like that (spotting prey, or predators). It's piped into the conscious mind without context however. We just get a visual "something is missing/it's fake" message.
My cat died in my arms. I woke up. I thought he wasn't real.
That sounds like a terrible surprise. I'm sorry.
You know, people come up with all types of interpretations, but there is something to it.