1873: Changes of state - The book of science

Changes of state
Van der Waals forces
Making things happen
Commentary

Johannes Diederik van der Waals chemistry

Changes of state

Atoms in a gas are not infinitely small
or unaffected by one another.
They are not merely kinetic Newtonian objects
with probable velocities
moving at random far apart in space.
If they were, the pressure of a gas
would vary smoothly with its temperature.
Johannes Diederik van der Waals
modified the kinetic theory of gases
developed by Maxwell and Boltzmann
to account for a molecule’s size
and its affects on its neighbors.
His equation let him predict
the phase transitions between stable states
where a gas becomes a liquid
or a liquid becomes a gas.

Van der Waals forces

Tiny hairs on the toes of a gecko
stick to leaves, ceilings, even plate glass
because they get extremely close
where small temporary
or permanent polarizations
cause molecules to act like magnets.

Making things happen

Science cannot predict when a look
becomes a laugh.
Two magnets may repel or attract.
Although a state of mind may be valuable,
it would be more profitable
if it were more predictable.

Newton taught that on the universal scale mathematics brings light to physics; Van der Waals applied mathematics on the atomic scale to explain the behavior of gases and the changes of state from solid, to liquid, to gas. Results of physical experiments demanding explanations suggest that an interplay between mathematics and physics is essential.

Van der Waals was influenced by the thermodynamics of Rudolf Clausius and the writings of James Clerk Maxwell, who praised his work.