> For completeness I include gravity because it's the only other fundamental interaction we arguably directly sense (inner ear fluid and fine hairs are part of

> For completeness I include gravity because it's the only other fundamental interaction we arguably directly sense (inner ear fluid and fine hairs are part of the same sensory organ, unlike our skin and the sun). Not sure why the organ doing the sensing matters. I'm talking about thermoreceptors in the skin, obviously. But just to be clear, I'm saying that you're actually sensing electromagnetic force in your inner ear _caused by_ gravity. Not gravity itself. Even if the hairs bend due to gravity alone, that force upon the sensory receptors is an electromagnetic one. But if you consider that 'direct' then you must also consider sensing of the weak force, as 'direct'. Whether it be via thermoreceptors or your retina. tldr gravity : bending hairs :: weak interaction : radium glow