IT would seem that some of the intriguing visual phenomena discussed by Dr. MacKay 1 may be due, not to cerebral or retinal factors only, but at least in part to preretinal factors, namely, ...

Giant's Causeway in Northern Ireland features around 40,000 exposed polygonal columns of basalt in perfect horizontal sections. Chris Hill/Photodisc via Getty Images The reason patterns often appear ...

Why does nature always create a pattern? – Saloni G., age 16, Alwar, Rajasthan, India The reason patterns often appear in nature is simple: The same basic physical or chemical processes occur in many ...