Entropy
Chapter 1 - Worldview
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Welcome to the Entropy page (the second building block)
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For the second building block, we will explore the entropy concept. It is not the things in themselves but the relationships between things that are impossible to keep unchanged.
Entropy is a measure of disorder or randomness in a system, central to thermodynamics and information theory. It quantifies how energy or information disperses, with isolated systems tending toward higher entropy over time. As an example: an ordered deck of cards (low entropy) becomes disordered (high entropy) through shuffling. Each shuffle introduces sensitivity to initial hand movements, making the final arrangement unpredictable.
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Key take-aways
- The entropy of a physical system is proportional to the quantity of energy no longer available to do physical work
- Entropy is the measure of change from order to chaos
- Low entropy means a high potential energy
- High entropy means a low potential energy
- Entropy creates our notion of time
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Core idea
The probability of a system
Entropy and probability are two related concepts.
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Imagine how one breath of wind can completely change the situation below in the orderly or the chaos situation.
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Deep dive
You experience the world as constantly changing. In a world built on the principles of Relational Quantum Mechanics, the only constant is change, and change leads to entropy, a concept with significant consequences.
Entropy gives energy the ability to do work. In this sense, entropy precedes energy.
So, in the never-ending process of increasing entropy from low to high, energy that can do work is created as part of the process; the rest becomes unusable as high entropy. Energy is at the most a byproduct of entropy.
In an eternally expanding universe, the clustering of matter - a necessary condition for the origin of life - is only possible if it also increases entropy.
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Transformation
In 1865, Rudolf Clausius, a German physicist and mathematician, named the concept entropy after the Greek word for 'transformation'.
- The second law of thermodynamics states that over time, the disorder of energy, namely entropy, increases inexorably, and the usable ordered energy decreases.
Entropy is a measure of disorder and chaos in nearly all its meanings.
- By order, the opposite state, we understand segregating things by their kind (e.g., similar properties or parameter values).
- Chaos is the state of a system (physical or dynamical) in which all sorts of elements are mixed evenly throughout space to make it homogeneous.
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Entropy
In standard wording, the entropy tendency means a tendency towards disorder or chaos, meaning a decrease of usable energy and an increase in the uniform distribution of anything within the system. This last part may sound surprising, but:
- Think about your home on a typical day. Clothes are in the wardrobe, dishes are neatly piled up in the kitchen, and food is stored in the fridge. This is a picture of low entropy with defined parts of high order within the total system.
- Think about a horror scenario after a children's party at home: clothes everywhere in every chamber, food spread over the coaches and beds, glassware and dishes around. This picture shows high entropy with no order and a high probability of finding anything anywhere.
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Entropy is not the same as energy
Do not confuse energy with entropy.
Let's consider fossil fuels, charcoal, oil, and even gas. They possess a high potential energy level and are in a low entropy state. They are the remaining of an even lower entropy state of the photons we receive from the sun. When we burn those fuels, we get heat. This is what we call energy because, for a short time, we can transform it into steam, electricity, motion, etc. In the process, we decrease the usable energy (the global oil stock) and pump heat and chaotic particles into the earth's atmosphere.
In practice, any self-sufficient system also receives energy from somewhere 'beyond' its system boundary. A simple real-world example is the rainfall cycle: water evaporates from the sea or land surface to form clouds, from which rain falls and returns to the sea via streams and rivers. The cycle relies on energy from the sun to power the evaporation that drives the seemingly counter-entropy 'upward' part of the cycle.
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Time
This unstoppable increase of unusable energy (entropy), postulated by classical thermodynamics, is the criterion for distinguishing between the past, the present and the future. Measuring the change in the amount of entropy tells you the order in which events occur: the lower-entropy state comes first, the higher-entropy state next, and the total-entropy state last.
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Entropy makes the world go round
There is a more profound puzzle underlying this spacetime confusion. At the deepest level of mathematical physics, time does not exist at all. According to Rovelli, there is just one basic equation that points to an arrow of time: the second principle of thermodynamics, which says that entropy is constantly increasing and that the journey from order to disorder is down a one-way street. We observe this journey because heat flows towards the cold things and one day, all the heat will dissipate, and we will experience neither the past nor the future.
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What makes the world go round is not energy, but sources of low entropy.
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We don't live by inhaling heat but by eating food, a source of low entropy that releases energy by digesting, transforming food into a higher entropy state.
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| The Order of Time - Carlo Rovelli |
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Entropy help predict the behavior of complex systems
Entropy serves as a foundational tool for understanding and predicting the behavior of complex systems, particularly in scenarios involving uncertainty, noise, or incomplete information. Entropy measures the disorder or uncertainty in a system’s state, making it invaluable for modeling complex systems (e.g., ecosystems, economies, or biological networks) where interactions are nonlinear and outcomes are sensitive to initial conditions. By prioritizing uncertainty management and leveraging data-driven constraints, the entropy approaches bridge the gap between theory and real-world complexity.
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Example: climate change
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| Climate change – a very difficult, very simple idea - Jennifer Coopersmith - Oxford University Press's Academic Insights for the Thinking World - 2015 |
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| Climate change, more specifically human-induced climate change, is a surprisingly simple idea.
The mathematician and philosopher, Bertrand Russell, summed up mankind’s activities as the rearrangement of matter on or near the Earth’s crust. Russell’s words need refining. The rearranging of matter is done in two different ways: by mechanical devices (such as levers), or by ‘heat-engines’ (such as muscle-power, or combustion engines). (Loosely speaking, anything that ‘farts’ is some sort of heat-engine.) A heat-engine consumes fuel and, by the Second Law of Thermodynamics, ‘always puts out some waste heat.’
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What science can tell you
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| Ilan Y. - The constrained-disorder principle defines the functions of systems in nature. - Front. Netw. Physiol. - 2024 |
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| Classical physics laws have been used to explain phenomena in the macroscopic world. Examples include the classical laws of motion, gravity, electromagnetism, thermodynamics, and energy. The constrained disorder principle (CDP) defines all systems in nature based on their degree of variability. |
| https://www.frontiersin.org/journals/network-physiology/articles/10.3389/fnetp.2024.1361915/full |
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