U can show him that Earth isn't getting smaller, because things WOULD be getting smaller, and our houses would be getting smaller, IF everything shrunk WITH Earth.
Buffers - mixtures of conjugate acid and conjugate base at ±1 pH unit from pH = pKa. Resistant to changes in pH in response to small additions of H+ or OH-. ... Polyprotic acids - dissociation of each H+ can be treated separately if the pKa values are different