Text Box: ...atoms shine very brightly for their size: a single atom of calcium, for example, will scatter as much light from a laser beam with a wavelength of 397 nm as a ground glass sphere of 600 times larger radius would. This is because of the phenomenon of resonance – the merest glimmer of incident radiation will cause the atom to 'sing' at its resonant frequency.
The atomic nanoscope, Andrew Steane (University of Oxford, Oxford, UK), Nature 414, 24-25 (1 Nov 2001)
Text Box: Most people assume that a wave, being central to all the phenomena we observe, has a uniform definition. But defining this basic concept isn’t so easy. Ask your colleagues and students to define a wave, and you may be surprised at the answers you get. Even wave professionals are prone to confusion and vagueness when confronted with such an apparently simple question. ... 
It is clear that waves are ubiquitous in nature and that they are central to the structure of matter and time as well as to many physical, biological and chemical phenomena. It is striking that the concept of waves is so hard to define, and the distinction between wave-like and non-wave-like behaviour can be so fuzzy. Taking all these examples into account, we stick with our definition of a wave as an organized propagating imbalance; just don’t ask us to define ‘organized’.
What is a wave? John A Scales (Department of Geophysics and the Center for Wave Phenomena, Colorado) and Roel Snieder Department of Geophysics, Utrecht University, The Netherlands), Nature 401, 739 (21 October 1999)
Text Box: Momentum Transfer
Momentum, and momentum alone, transfers between radiatons in any and all interactions.
(Hence, there is no force that could be deemed unique or "fundamental" in nature, be it gravitational, electromagnetic or nuclear.)
The figures below illustrate the exchanges that take place between two atoms, say, A and B, in their ground, or unexcited, state.
These are perhaps better visualized by considering the radiatons from, say A to B, to move unidirectionally (that is, non-vibrationally) across the (imaginary) atom-vacuum border. 
The effect from B to A would move in a similar manner but in reverse, the transfers seemingly to "pass through" each other.
The excited state is taken up in Part 6, next.
(For the full text, please see 'The Communion of Atoms' in A Synopsis.)
          Go to Part 6 of 6
A Synopsis The Cosmos The Spin
ADDENDA The Cosmological Redshift The Neutrino
Two-Slit Tests The Galaxy Nuclear Reactions
NASA Tests Gravity The Sun
KamLAND Test Anti-Gravity The Pulsar
UCLA Test Relativity Superconductivity
Q and A Mass-Energy Fusion Energy
 Eugene Sittampalam
 12 July 2008