This is NOT news, Scientific American did an entire article on it months ago. It's just a temperature-differential driven flow - the beer near the edge of the glass warms and rises. The beer in the center sinks. In stout, where this occurs. is thick enough, and the bubbles are small and long-lived enough to be carriied with the flow. It doesn't happen in Lagers or moth Ales, just Porters and Stouts
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This is NOT news, Scientific American did an entire article on it months ago. It's just a temperature-differential driven flow - the beer near the edge of the glass warms and rises. The beer in the center sinks. In stout, where this occurs. is thick enough, and the bubbles are small and long-lived enough to be carriied with the flow. It doesn't happen in Lagers or moth Ales, just Porters and Stouts