https://conormacdonald.com.au/tags/negative-bulk-modulus/ Recent content in Negative Bulk Modulus on Conor MacDonald Hugo -- gohugo.io en Wed, 18 Mar 2026 00:00:00 +0000 https://conormacdonald.com.au/posts/metamaterials-03-negative-parameters/ Wed, 18 Mar 2026 00:00:00 +0000 https://conormacdonald.com.au/posts/metamaterials-03-negative-parameters/ <p>At the end of Post 2, we derived the wave equation and discovered something unsettling sitting inside it. If the effective density of a material goes negative, the character of the equation changes. Instead of oscillatory solutions that propagate energy through space, you get exponential ones: a wave entering such a region decays rather than travels. We called this evanescent decay, named the resulting frequency band a band gap, and noted it was central to everything interesting in acoustic metamaterials.</p>