The mesmerising movement of ink through water is in fact nothing more than the random motion of molecules.
Ink enters the fluid as one dark blob, before diffusing from this original region of high concentration to regions in the water with lower concentration.
This happens because randomly moving water molecules collide with ink molecules, causing them to spin off in different directions. As regions with more ink molecules undergo more collisions with water molecules, the ink molecules from these regions will, on average, move into areas with fewer molecules.
The distance these ink molecules travel through water depends on their size; bigger molecules are slowed down by friction more than smaller molecules.
While the underlying mechanics may be simple, they play out in beautiful patterns of near-infinite variety.
Jana Howden completed a double degree in Arts and Science at Monash University in Melbourne, Australia.
Read science facts, not fiction...
There’s never been a more important time to explain the facts, cherish evidence-based knowledge and to showcase the latest scientific, technological and engineering breakthroughs. Cosmos is published by The Royal Institution of Australia, a charity dedicated to connecting people with the world of science. Financial contributions, however big or small, help us provide access to trusted science information at a time when the world needs it most. Please support us by making a donation or purchasing a subscription today.