2.1 Nature of Matter
15
in mechanical equilibrium can cause internal oscillations, provided that the added
energy is insufficient to deconfine the system, and does not quickly cause particles
to thermalize or escape. Parts of the system in proximity can transfer distortional
energy to the next part in sequence, producing a wave. Such a wave in a material
substance is sound. Sound waves have become important to life systems, and will
be treated in Chap. 5. More generally, a ‘wave’ is a disturbance that self-propagates
across space. Waves exist in materials and in fields.
Fields are defined for each of the known interactions in nature, often divided
into the categories of gravitational, weak, electromagnetic, and strong. Each such
field can have waves by jiggling the source of the field. Electromagnetic waves,
made by jiggling charges, are of particular importance in biological systems due
to their strength and range in macrosystems, and so they will be extensively treated
later. Material waves are distinct from field waves in that material waves consist of a
series of coupled oscillations in a substance; field waves do not require a background
material. Sunlight passes through the vacuum of outer space.
The bonding of atoms in a molecule comes about through the effects of the
electromagnetic forces and the quantum behavior of the outer atomic electrons.
When atoms or molecules are pressed together, their electron clouds come closer
together, resulting in electrical repulsion, but also repulsion due to the Pauli
exclusion principle, a quantum effect that keeps electrons from occupying a single
quantum state. Pressed even further, electrical repulsion between nearby nuclei
becomes important.
Life relies on the existence of a variety of complex structures and on activity.
Carbon, silicon, nitrogen, phosphorus, sulfur and boron are capable of linking
up to form large molecules. Carbon is much better at such feats than the other
candidates. Life on Earth uses carbon-based compounds in liquid water, where they
can be active. Water is a relatively abundant compound with several properties
advantageous for life. Because the water molecule has a relatively large dipole
moment, pointing from the oxygen to the middle of the pair of hydrogen atoms,
liquid water makes a good solvent for other polar molecules and ions (Fig. 2.1).
Unlike most materials, when water freezes, it expands (between 4 to 0 ◦ C), so that
ice is less dense than liquid water. The fact that ice floats makes ponds and lakes
Fig. 2.1 Good solvent
molecules
15
in mechanical equilibrium can cause internal oscillations, provided that the added
energy is insufficient to deconfine the system, and does not quickly cause particles
to thermalize or escape. Parts of the system in proximity can transfer distortional
energy to the next part in sequence, producing a wave. Such a wave in a material
substance is sound. Sound waves have become important to life systems, and will
be treated in Chap. 5. More generally, a ‘wave’ is a disturbance that self-propagates
across space. Waves exist in materials and in fields.
Fields are defined for each of the known interactions in nature, often divided
into the categories of gravitational, weak, electromagnetic, and strong. Each such
field can have waves by jiggling the source of the field. Electromagnetic waves,
made by jiggling charges, are of particular importance in biological systems due
to their strength and range in macrosystems, and so they will be extensively treated
later. Material waves are distinct from field waves in that material waves consist of a
series of coupled oscillations in a substance; field waves do not require a background
material. Sunlight passes through the vacuum of outer space.
The bonding of atoms in a molecule comes about through the effects of the
electromagnetic forces and the quantum behavior of the outer atomic electrons.
When atoms or molecules are pressed together, their electron clouds come closer
together, resulting in electrical repulsion, but also repulsion due to the Pauli
exclusion principle, a quantum effect that keeps electrons from occupying a single
quantum state. Pressed even further, electrical repulsion between nearby nuclei
becomes important.
Life relies on the existence of a variety of complex structures and on activity.
Carbon, silicon, nitrogen, phosphorus, sulfur and boron are capable of linking
up to form large molecules. Carbon is much better at such feats than the other
candidates. Life on Earth uses carbon-based compounds in liquid water, where they
can be active. Water is a relatively abundant compound with several properties
advantageous for life. Because the water molecule has a relatively large dipole
moment, pointing from the oxygen to the middle of the pair of hydrogen atoms,
liquid water makes a good solvent for other polar molecules and ions (Fig. 2.1).
Unlike most materials, when water freezes, it expands (between 4 to 0 ◦ C), so that
ice is less dense than liquid water. The fact that ice floats makes ponds and lakes
Fig. 2.1 Good solvent
molecules