Have you ever thought about the composition of foam? As science explains, foam is neither classified as a liquid, nor as a gas, and nor as a solid - but as the three of them at the same time. Presently, there's not enough evidence to give a clear explanation for its formation, however it has been suggested that most foams are made up of gas in between bits of liquid. Its behavior, on the other hand, remains an undiscovered mystery. What we know for sure is that we can distinguish between different types of foam - for instance, the foam that forms from your washing soap looks different from your shaving foam, the difference being in the stiffness. Other than that, we've got nothing apparently concrete we can learn from this weird, bubbly substance.
4. Why does static electricity happen?