Reply #30: No, there are numerous ways to detect photons.

[DrWeird]

CCDs, electron multiplyer tubes, etc.

What's happening is, photons are reflecting off of the surface of the sand, traveling to the back of your eye, hitting a receptor, where it increases the energy of an electron from a pi-bonding orbital to a pi-anti bonding orbital of a very specific molecule, this triggers a stereochemical change of said molecule, which triggers a cascade chemical reaction which leads ultimately to your brain, where you interpret it as "a grain of sand."

All very much verifiable through scientific experiments, and recored in peer-reviewed scientific journals which is far more reliable than "what my friends tell me."