--------- #1345 - Absolute Zero Temperature Strangeness?
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- Absolute Zero is the lowest temperature can get. It is zero degrees Kelvin ,or, -273 degrees Centigrade. Temperature is the measurement of the vibration of atoms. We feel atom vibrations as “heat”. Vibrating can also emit infrared radiation that we can also feel as heat. Another way we can feel the heat is through convection. Vibrating atoms and infrared radiation vibrate the molecules in the air. These molecules move throughout the room and bring a warm feeling to your skin. The absence of heat is reduction of the vibration of atoms and it is called “cold”. Just as “dark” is the absence of “light”.
- Absolute Zero is a cold as it gets. When the vibration of atoms stops you are there. Of course, the quantum jitter of atoms never stops. So, atoms and particles, can not be completely stopped regardless. This is defined as the principle of Quantum Uncertainty. Not a topic for this review. This review is about temperature and about the vibration of atoms which is the energy of motion.
- The energy of motion is called “ Kinetic Energy”. The faster the motion the more the Kinetic Energy the hotter it feels. It is also know as “Thermal Energy”. The measurement of Thermal Energy is called temperature. As atoms slow down and they reach lower temperatures they can change state. Different elements and different molecules change states at different temperatures.
- Water vapor is a gas above 100 degrees Centigrade. When the temperature falls below 100 C the gas changes state into a liquid. When the temperature falls down below 0 C the liquid changes state and becomes solid ice.
- The measurement of temperatures is an arbitrary number. Science simply chose the states of pure water to set the values of 100 degrees between the two states. But, science also learned that the states and temperatures also depend on pressures. Not all situations could be read at atmospheric pressure at sea level. Ammonia gas, for example, liquefies at 132.4 Centigrade and 111.3 atmospheric pressure.
- The pressure affects the vibration of atoms also. Higher pressures can keep atoms form vibrating as much just as lower temperatures are reduced vibrations. Ammonia gas turns into a gas at room temperatures and pressures. This property is used in refrigeration. A gas absorbs a small amount of heat from its surroundings when it changes states from a liquid to a gas.
- In a closed system, a compressor motor outside the refrigerator increases the pressure and turns the gas into a liquid. The liquid is pumped inside the refrigerator and released into coils of tubes that are at atmospheric pressure. When the liquid is released the change of state into a gas absorbs heat from inside the refrigerator. The gas is pumped back outside the refrigerator where the compressor changes it back into a liquid and the heat is released into the kitchen.
- Science studied many different gases to learn at what temperatures and pressures each changed state into a liquid. Plotting this data temperature versus pressure proved to be a linear relationship. The plot was a straight line as pressure increased and temperature decreased liquefaction of gases occurred. However, some gases simply refused to liquefy regardless of how much pressure was applied. This happened with ordinary air.
- The air was mostly nitrogen and they decided that the temperatures were just not low enough for liquefaction to occur. Here is what they discovered as temperatures were reduced lower and lower:
------------------ Water Vapor ----------- 373.946 C -------- 217.7 atmospheres
------------------ Ammonia -------------- 132.4 C ----------- 111.3 atmospheres
------------------ Oxygen ----------------- (-118.6 C) --------- 49.8 atmospheres
------------------- Nitrogen ---------------- (-146.9 C) ---------- 33.5 atmospheres
----------------- Hydrogen ---------------- (-239.95 C) ---------12.8 atmospheres
------------------ Helium ------------------ (-267.96 C) ---------- 2.24 atmospheres
- Liquid helium enters some very unusual states caused by atoms behaving within Quantum Mechanics theory at these temperatures. One is “ Super fluidity” Helium liquid will have zero viscosity and infinite thermal conductivity. With zero viscosity the liquid helium will flow uncontrollably and it will always maintain he exact same temperature throughout. Liquid helium will actually rise up the sides of its container over the top and down to spread across the table. It is impossible to set up a thermal gradient in this fluid. Application of heat at a spot will conduct at 20 meters per second to bring the entire liquid to the same temperature.
- A phonon is a mechanical vibration ( like a sound vibration ) is a lattice structure of atoms at a resonance frequency. Superconductivity is like a superfluid for electrons that can travel through a conductor lattice structure with zero resistance. Just as a temperature gradient can not be created across a superfluid, a voltage gradient can not be created across a superconductor.
- Superconductivity occurs because of the inter action between electrons and the vibrating lattice of ions in the conductor. With a resonant phonon two electrons can pick up this oscillating frequency and become a “ Cooper Pair” of electrons. The paired electrons can be 100 nanometers apart while the ions in the lattice are 0.1 to 0.4 nanometers apart. In a superconductor cooled to a critical temperature the Cooper Pairs move through the conductor in a coordinated way. Resistance can not occur because a large number of coordinated pairs would have to be slowed down all a once.
- Once superconducting occurs no magnetic field can penetrate the conductor. this can have the effect of levitating the superconductor above a permanent magnet. ( See Meisner Effect”) .
The plot of temperature versus is a straight line. To define the degrees Kelvin one end of the sloped line is a zero temperature and zero pressure. The other end of the line is the Triple Point for pure water. The Triple Point is where temperature and pressure are just right to allow water vapor, water liquid, and water ice to all exist at the same time. All three states of water matter are present at 273.16 Centigrade and 4.58 millimeters of mercury pressure. The straight line between the points defines the temperatures in degrees Kelvin.
- The straight line extends from Absolute Zero to the temperature of the Big Bang. It goes from zero degrees Kelvin to 350,000,000,000,000,000,000,000,000,000,000 degrees Kelvin. Now that is hot. To learn how this temperature calculation was made see Review #727 , Absolute Zero Temperature. Or, #1346 How Hot is it at the Big Bang?
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707-536-3272, Wednesday, December 7, 2011
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