The light by which cells speak: Gurwitsch rays and biophotons
An onion-root experiment led Alexander Gurwitsch to propose that living cells emit ultraweak radiation capable of influencing division in neighbouring cells.
Living tissue produces measurable ultraweak photon emission, much of it linked to oxidative chemistry.
Emission alone does not establish that cells use the photons as a functional communication channel.
Two roots and a quartz window
Gurwitsch reported increased mitosis when one onion root faced another through quartz, while ordinary glass blocked the apparent effect.
Light too faint to see
Modern photomultipliers confirm that cells emit extremely weak light as excited molecules produced by metabolism and oxidation return to lower energy states.
The decisive question is whether receiving cells detect those photons and alter behaviour. Modern experiments use sensitive detectors, barriers and environmental controls.
Ultraweak emission already offers a non-invasive window into metabolic stress. Its possible role in coordination would add an optical layer to cellular signalling.