MXD, welcome to the obsession & AHB.
Yeasts have three distinct phases of life in wort (unfermented beer). They are: Respiration; Fermentation; and Sedimentation.
In the Respiration or Lag phase the yeast uses the oxygen in the wort to derive energy from both the wort and internal sources for reproduction. Internal energy stores of glycogen will be depleted as the yeast prepares for fermentation. The enzymes necessary for sugar metabolization are produced during this phase. These enzymes will be improperly developed if the wort has large amounts of corn sugar. Carbon dioxide is generated in this phase, as are flavor characteristics such as esters and diacetyls. No alcohol is produced during this phase. This phase will generally last for 24 hours after pitching or less.
In the Fermentation phase the yeast continues to reproduce, but no oxygen is used. The free oxygen will be scrubbed out by the CO2. During this phase the yeast reproduces to maintain an optimal population throughout the wort. Here is where the sugars are converted to alcohols. The yeast will stay in suspension long enough to attenuate the wort to the desired degree. Often hydrogen sulfide (H2S) is produced during this stage, but it will normally be carried out of the wort by the CO2. Diacetyl and other fusel alcohols that are normal products of fermentation will be reduced or eliminated during this phase. This phase will include both Low Kraeusen and High Kraeusen, and the pH will drop to about 4.5-4.8, which signals the start of the sedimentation phase.
In the Sedimentation phase the yeast realizes that the energy stores and food are near depletion. The cells go dormant and settle to the bottom of the fermenter. Glycogen is produced, which is used to maintain the cell during dormancy, as well as to provide a new energy source for initial activity if roused into fresh wort
Your yeast is clearly in the 1st phase. Don't sweat it if the air lock doesn't bubble... just keep your eye out for the wort to change colour, a scum line to form on your fermenter level with the top of the wort an sediment appearing on the bottom. These are all signs that fermentation is occurring.
