# The laws of thermodynamics  ## Metadata - Author: [[Khan Academy]] - Full Title: The laws of thermodynamics - Category: #articles - Summary: The laws of thermodynamics explain how energy is transferred and transformed in living systems. The First Law states that energy cannot be created or destroyed, while the Second Law explains that energy transfers increase disorder, or entropy, in the universe. Living beings maintain their organization by constantly using energy, which ultimately increases the entropy of their surroundings. - URL: https://www.khanacademy.org/science/ap-biology/cellular-energetics/cellular-energy/a/the-laws-of-thermodynamics ## Highlights - At first glance, the first law of thermodynamics may seem like great news. If energy is never created or destroyed, that means that energy can just be recycled over and over again, right? Well…yes and no. Energy cannot be created or destroyed, but it can change from more-useful forms into less-useful forms. As it turns out, in every real-world energy transfer or transformation, some amount of energy is converted to a form that’s unusable (unavailable to do work). In most cases, this unusable energy takes the form of heat. Although heat can in fact do work under the right circumstances, it can never be turned into other (work-performing) types of energy with 100% efficiency. So, every time an energy transfer happens, some amount of useful energy will move from the useful to the useless category. ([View Highlight](https://read.readwise.io/read/01jcyreaxg5ntbq94krkns5vfa)) - You, like all living things, are an open system, meaning that you exchange both matter and energy with your environment. For instance, you take in chemical energy in the form of food, and do work on your surroundings in the form of moving, talking, walking, and breathing. ([View Highlight](https://read.readwise.io/read/01jq7fg7dvd9ta7x6mgtj7rycp)) - Energy cannot be created or destroyed, but it can change from more-useful forms into less-useful forms. As it turns out, in every real-world energy transfer or transformation, some amount of energy is converted to a form that’s unusable (unavailable to do work). In most cases, this unusable energy takes the form of heat. ([View Highlight](https://read.readwise.io/read/01jq7fm53chs5y2gvr0y6aqyh3)) - Although heat can in fact do work under the right circumstances, it can never be turned into other (work-performing) types of energy with 100% efficiency. ([View Highlight](https://read.readwise.io/read/01jq7fmv81d5dqfep0a761fhs4)) - processes that locally decrease entropy, such as those that build and maintain the highly organized bodies of living things, can indeed take place. However, these local decreases in entropy can occur only with an expenditure of energy, where some of that energy is converted into heat or other non-usable forms. The net effect of the original process (local decrease in entropy) and the energy transfer (increase in entropy of surroundings) is an overall increase in the entropy of the universe. ([View Highlight](https://read.readwise.io/read/01jq7frsa73yc2fkcwf37k34x8))