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------------------ 1914 - Thermodynamics and the Fate of the Universe
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------------------------------ S = K * log W on Boltzmann’s gravestone
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------------------ Entropy = ( Boltzmann Constant ) * log ( number of microstates )
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- Thermodynamics was invented during the study of steam engines in the 1800’s. Physicists wanted to learn how to make them more efficient at doing work. Maybe even get 100% efficiency if that was possible. In the process of this study they developed four laws that had to be followed in nature. They had no idea that these laws that work on steam engines also work on every process in the Universe including the Universe itself. Here are their simple laws:
(1) The Conservation of Energy. Energy can be transformed from one form to another but it can never be destroyed, or created. The amount of energy in a closed system is always the same.
(2) The Entropy of a closed system will either stay the same or increase. Entropy will never decrease.
(3) Energy is at a minimum at absolute zero temperature, but never quite zero. Temperature is actually the measure of the average vibrations, or kinetic energy, of a bunch of moving atoms. Even at absolute zero, 0 Kelvin, atoms still vibrate at the quantum level. Of course, they did not know quantum’s until 1910.
- What is so amazing is that these laws apply to everything from molecular engines to Blackholes in the cosmos. Take for example the muscles in your arm. These laws govern the energy transformations from ATP molecules that provide the fuel for myosin molecules in muscle tissue to move along action filaments, pulling the muscle fibers to which they are attached. These laws even apply to bacterial colonies and to computer memories.
- Entropy is the most mysteries concept because it has been so ill defined and misinterpreted over the years. But, you can understand it if you care. Entropy is all around us in our daily lives. It is what makes a rock fall from your hand to the ground. It is what happens to a hot teapot when it cools down in the sink. It is why a hole in the tire makes it go flat. It is why ice melts when it sits at room temperature.
- Thermo - dynamics is the study of “Thermo” which is thermal energy, or heat, and “dynamics” which is the study of movement. Thermodynamics is the study of the movement of energy. Energy is defined as the “ability to do work” And, work is defined as a “change in energy“.
---------------------- E2 - E1 = W
---------------------- dE = dW
- Energy can transform into many different forms:
----------- Kinetic -------- the energy of motion, E = ½ m*v^2
----------- Potential ------- the energy of voltage and gravity, power = V*I
----------- Thermal -------- the energy of heat, the kinetic energy of atoms, “dQ” = C*dT
C = heat capacity. T = temperature
----------- Sound ----------- the energy of a medium in motion
----------- Light ----------- the electromagnetic energy, E = 6.6*10^-34 * frequency, joule* seconds
----------- Elastic ----------
----------- Electric --------- the energy of electric charge, E = k*Q1*Q2 / r
----------- Magnetic -------- the energy of magnetic moments
----------- Electromagnetic - the energy of E = 6.6*10^-34 * frequency
----------- Nuclear --------- E = mc^2
----------- Mass ----------- the energy of E = m*c^2
- Entropy is the transformation of all these different types of energy from one to another, or the dispersal of energy in any form. Entropy ( “S” ) is the measure of the change in heat energy to the average temperature.
----------------- S = “dQ” / T
----------------- S = Joules / Kelvin
- Let’s take the example of the hot teapot to go through the math and get more familiar with this term, Entropy:
- We are using thermal energy in this example, not unlike the steam engine. Entropy is measuring the dispersion of energy at some specific temperature. The dispersion is always in the direction of increasing Entropy. Entropy never decreases. We start with kilowatt-hours of electrical energy to heat up the teapot to reach equilibrium at 100 C. Turn off the stove. Let the pot cool down. It eventually cools to equilibrium at room temperature of 20 C. Here are the steps:
---------- (1) The teapot reaches 373Kelvin and contains 200,000 joules of heat energy.
---------- (2) It cools down to 293K and has 40,000 joules of energy at room temperature.
---------- (3) The teapot cools down losing 160,000 joules of energy while the air in the room warms up gaining 160,000 joules of heat energy.
------------- Entropy from the teapot :
------------- Entropy = change in energy / average temperature
------------ S = “dQ” / T
------------ S = 200,000 - 40,000 / (393K - 293K) / 2
------------ S = 160,000 / 333K
------------ S = - 480 joules / Kelvin
- The - 480 joules / Kelvin energy lost from the teapot to the room.
-----------------Entropy for the room:
---------------- S = 160,000 / 293K
---------------- S = 546 joules / Kelvin
- The Entropy in the closed system of the teapot in the room has increased from 480 to 546. Entropy has increased by 66 joules / Kelvin. Entropy always increases.
- That analysis seems very straight forward. Why is Entropy confusing? Well, Entropy is involved in so many situations it has acquired so many definitions. Here are some of these definitions for all the same thing:
--------- Entropy is the change to a more disordered state at the molecular level.
--------- Entropy describes the number of possible microscopic configurations of the system. Entropy is the natural logarithm of the number of microscopic states available to a system times Boltzmann’s Constant. S = k*ln N. k = Boltzmann’s constant = 1.318*10^-23 joules / Kelvin. ( Request Review #728 to learn about Boltzmann’s Constant ).
---------- Entropy is the measure of the spontaneous dispersal of energy.
---------- Entropy is the ultimate evolution from order to disorder. The higher the Entropy the greater the disorder.
---------- Entropy is energy broken down into irretrievable heat.
---------- Entropy is the direct measurement of the randomness of a system.
---------- Entropy is the measure of unavailability of a system’s energy to do work.
---------- Entropy is what keeps us from designing a 100% efficient engine. We can never build a perpetual motion machine for this reason.
- In order to get this disorder concept better understood let’s take the example of the melting ice cube. When ice melts into a liquid it is increasing Entropy. Therefore increasing disorder. The ice molecules are in a fixed arrangement of order. Melted water molecules are in a relatively free arrangement of disorder. The entropy in the puddle is greater than the entropy in the ice cube.
- My last definition is that Entropy is the Dark Force that will end the Fate of the Universe as a “heat death“. The Universe will expand and disperse its energy forever with increasing Entropy until it is a cold, dark, dispersion of random particles in equilibrium in empty space. Even the Blackholes will evaporate to this state of maximum Entropy. The other thought is that the Big Bang must have been at minimum Entropy when it started. Ever since it has been smashing us down with random forces that can not be reversed. It is the Dark Force in the Universe. It is the “arrow of time”.
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- Entropy is mathematical. It is the result of statistics. The is more possibilities of things to be disorderly than orderly. So, if things vibrate, fluctuate, change then they are eventually gravitate to “ disorderly’. That is entropy. The same thing happens with atoms.
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- Joule - is a unit of Energy whereby one Newton of Force acts over one meter of work.
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- Newton - is a unit of Force that will accelerate a mass of 1 kilogram to 1 meter / second^2
------------------------------ F = m*a
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----------------------------- Force = mass * acceleration
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----- 707-536-3272 ---------------- Tuesday, January 10, 2017 -----
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