The First Law of [[Thermodynamics]] is a statement of the principle of conservation of [[Energy]]. It asserts that: Energy cannot be created or destroyed, only transformed from one form to another or transferred between systems. The First Law of Thermodynamics as an allegory could be likened to the story of a traveller’s journey: Imagine a traveller, Energy, who carries a bag of treasures (the total amount of energy in the universe). This bag is magical — no treasure can ever be taken out or added to it, but its contents can be rearranged, shared, or exchanged. The Allegory: 1. Heat () is a gift Energy receives. Sometimes, Energy meets people along the way (the system). They might give her gifts of warmth and light (heat). These gifts don’t add to her bag but can be transformed into new tools or actions. 2. Work () is Energy’s labour. Energy uses her treasures to accomplish tasks, like building bridges, moving mountains, or pushing wheels. Each time she works, her tools (energy in one form) are depleted in one place but show up as something new elsewhere. 3. Internal energy () is Energy’s vitality. After a long day of receiving gifts and doing work, Energy might feel stronger or weaker depending on the balance. The change in her vitality reflects how much of her treasures she chose to keep within herself versus how much she gave to the world. The Journey’s Truth: No matter what Energy does — receives warmth, expends effort, or keeps some vitality for herself — the treasures in her bag are never lost or added to. They only change form, endlessly shaping the world around her while always conserving the whole. • This law applies universally and underpins many processes in physics, chemistry, and engineering. Example: When you heat a gas in a closed container, the energy from the heat increases the gas’s internal energy or is used to do work (e.g., expanding against the container walls). `Concepts:` `Knowledge Base:` [[Digital index]]