Entropy is the natural tendency of any system to move from order to disorder in the absence of an external force
In project work, the disorder is created by uncertainty. These uncertainties come in two forms. Reducible and irreducible uncertainty. In the absence of external forces, the naturally occurring and event based uncertainties of all project work creates risk to the project's success through the variances that result - the Entropy of the Project drives this risk created by uncertainty. Research shows most projects fail through managerial failures, not technical failures. Most of these failures are due to unaddressed risk . And as is always the case
Risk Management is how Adults Manage Projects - Tim Lister
The development of software products or services is a collection of tasks and decisions to produce these outcomes for the organization paying for their development. The measurement of processes producing these outcomes is important to those paying since the process of developing the software not only creates value, but also creates cost.
In physical systems to reduce entropy, energy must be added to the system to prevent the creation of disorder. This energy is called Project Management or in general Management. This is the role of Management - to restrict to increase of entropy of the work environment. Management requires a process, so the process is part of entropy reduction as well. Management is applying a process to reduce entropy.
Uncertainty and variability are caused by probabilistic events and statistcal natural variances that force the systems (project) to deviate from a regular and predictable behavior.
In operational systems - projects, software development, DevOps - reducing variability or uncertainty is an important success issue. Reducing this uncertainty enables the work processes to increase predictability and managerial efficiency. Again reducing this uncertainty - that creates entropy - requires effort. This effort is energy in the principle of entropy management.
As always, to manage in the presence of uncertainty and to reduce the entropy of all project work, we need to make estimates of the amount of uncertainty and the amount of effort needed to make these reductions requires we estimate these attributes.
Dealing with uncertainty in project work consists of three activities 
- identifying sources of project development uncertainty
- quantifying project uncertainty
- Using such uncertainty measure for improving decision-making process with respect to projects.
When uncertanty exists on projects, estimates are needed to manage in the presence of uncertainty. Without estimates, we cannot make informed decisions in the presence of uncertainty. Just like physical systems, project systems have entropy that must be managed by spending energy - physical intervention to reduce uncertainty.
- "An Entropy-Based Approach for Measuring Project Uncertainty," Arden Asllani and Lawrence Ettkin, Academy of Information and Management Sciences Journal, 2007.
- "An entropy-based uncertainty measure of process models," Jae-Yoon Jung, Chang-Ho Chin, and Jorge Cardoso, Information Processing Letters, 111, (2011), 135-142
- “A risk management methodology for project risk dependencies,”T. W. Kwan and H. K. N. Leung, IEEE Transactions on Software Engineering, Vol. 37, 2011, pp. 635- 648.
- "An Entropy Based Approach for Risk Factor Analysis in a Software Development Project," Pradnya Purandare, International Journal of Applied Engineering Research, Volume 11, Number 4 (2016) pp 2258-2262
- "An Information-Entropy-based Risk Measurement Method of Software Development Project," Rong Jinag, Journal of Information Science and Engineering 30, 1279-1301 (2014)