- 3213 - TEMPERATURE - what it means to have one? Scientists are probing the extreme ends of the spectrum of what’s called “absolute temperature“. At the upper limit, absolute hot is a theoretical furnace where the laws of physics melt away. Absolute zero is cold, so cold there’s nowhere to go but up. This absolute zero is almost within scientists’ grasp.
------------------ 3213 - TEMPERATURE - what it means to have one?
- Temperature is always a relative measurement. The air is below freezing, her fever is above normal. Relative to what? At the extreme ends of the temperature spectrum is what’s called “absolute temperature” At the upper limit, absolute hot is a theoretical furnace where the laws of physics melt away.
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- On the cold side, absolute zero cold so cold there’s nowhere to go but up. Physicists have almost got there.
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- The atoms that make up matter are always moving. Temperature measures those atoms’ “kinetic energy“, or “energy of motion‘. The faster they move, the higher their temperature. Absolute zero, though, is almost perfect stillness. Atoms are no longer moving, well hardly at all.
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- Nothing in the universe has ever reached absolute zero temperature as far as we know. Even space has a background temperature of 2.7 kelvins. But we do now have a precise number for it: -459.67 Fahrenheit, or -273.15 degrees Celsius, both of which equal 0 kelvin.
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- Different materials vary in how cold they can get, and theory suggests we’ll never get to absolute zero.
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- “Bose-Einstein Condensate” is a fifth state of matter that only exists within a sliver of absolute zero. At such a low temperature, individual atoms overlap so much that they collapse into a single “quantum state” where they collectively act as a single entity. The discovery of Bose-Einstein Condensate has opened a new field of science in which physicists can probe “quantum behaviors“.
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- Instead of relying on bits, the 1s and 0s that regular computers use, “quantum computers” use qubits to make calculations. In theory, these machines can conquer problems much faster than today’s computers. But to work, their atoms or molecules must be cooled to a couple hundredths of a degree above absolute zero, a realm where quantum features aren’t lost in the electrical noise that heat can create.
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- When helium gets cold, it gets weird: It can glide friction-free through narrow tubes, sustain currents for long periods of time and flow up and over a container’s sides. Scientists describe it as a “superfluid“.
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- Superfluids might exist in neutron stars, the small, dense relics of supernovas not massive enough to form a blackhole. Superfluids have also led to the discovery of supersolids, which have the odd property of being able to flow through themselves.
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- What is the coldest “natural” place in the Universe. Although temperatures plummet on the dark side of the moon and the shadowy craters of Pluto, those locales look balmy compared with the “Boomerang Nebula“. About 5,000 light-years away, this star system is just 1 kelvin above absolute zero.
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- To get temperatures down to absolute zero, scientists have used vacuums and lasers in elaborate experiments to cool atoms of a gas. A vacuum can cool a gas without condensing it into a liquid or solid but its atoms still move. That’s where lasers come in.
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- In order to chill an atom, a series of lasers intersect to slow its momentum. When an atom absorbs a light particle, or photon, from a laser, it emits another photon. When physicists tune the lasers in just the right way, an atom traveling in one direction absorbs one photon and then emits another in a different direction and at a higher energy.
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- The atom will then slow down, photon by photon. By catching an atom in the crosshairs of multiple lasers, researchers can decrease its momentum from every direction, called laser cooling.
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- But there’s a way to go even lower. A technique called “evaporative cooling” siphons off a gas’ highest-energy atoms, like soup cooling by releasing heat as steam. By combining lasers and evaporative cooling in new ways, scientists have chilled gases to about 50 trillionths above 0 kelvin. It’s not zero, but it’s close enough.
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------------------------ Here is some history about this cooling process:
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- Year 1926: Chemists first describe a method, called ‘adiabatic demagnetization“, that uses magnetic fields to cool materials below 1 kelvin. In 1933, scientists employ it to chill a salt to 0.25 kelvin. That’s low, but not as low as laser cooling can go.
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- Year 1978: First demonstration of laser cooling takes materials to 40 kelvins; 10 years later, physicists use laser cooling to achieve 43 millionths of a kelvin.
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- Year 1997: Three physicists share the Nobel Prize for inventing laser cooling.
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- Year 2015: Stanford University researchers chill a gas made of rubidium — a soft metal used to make solar cells — to 50 trillionths of a degree above absolute zero, setting a new record.
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- Year 2017: Physicists at the National Institute of Standards and Technology in Boulder, Colorado, chill an aluminum membrane to 0.00036 kelvin, lower than theory predicted possible for the material. The experiment suggests a way to see quantum effects, like a single object coexisting in two places at once.
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-------------------------------- Other Reviews available:
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- 3102 - TEMPERATURE - dimensional analysis to Big Bang? The math used is called “dimensional analysis.” It is a simple concept. To learn it we will try it out on a pendulum before we try it out on the Universe. Measurements in physics and astronomy can involve 3 dimensions: length (space), time, and mass (energy). We refer to these as dimensions and they are measured in units: meters, seconds, kilograms.
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- 3065 - TEMPERATURE - absolute zero degrees. Physicists at the National Institute of Standards and Technology in Boulder, Colorado, chill an aluminum membrane to 0.00036 Kelvin, lower than theory predicted possible for the material. The experiment suggests a way to see quantum effects, like a single object coexisting in two places at once
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- 2946 - TEMPERATURE - a race to the bottom? - Scientists are probing the extreme ends of the spectrum of what’s called “absolute temperature“. At the upper limit, absolute hot is a theoretical furnace where the laws of physics melt away. On the flip side, absolute zero is cold, so cold there’s nowhere to go but up. This absolute zero is almost within scientists’ grasp.
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- 2564 - TEMPERATURE - calculating global Warming? How to measure the temperature of stars? Knowing the temperature of the Earth how to calculate the total energy being radiated? We live on the surface of a 2,000,000,000,000,000 one hundred light bulbs. And, the Sun that is warming us has a surface temperature of 6,000 degrees Kelvin. How do we know these things?
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- 2563 TEMPERATURE - Getting Temperature from Light? If we measure the frequency emitted we know the energy gap between orbits for that particular atom. And , if we know the energy gaps for each element we can measure the frequency of radiation and identify the element that created. it. That is how astronomers know the makeup of stars and gas nebulae that are billions of light years away.
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- 2405 - Zero is nothing, but Absolute Zero is something else.
- 2377 - “Defining the Atom”
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- 2333 - “Rainbows can Tell Us What the Universe is Made Of.”
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- 2555 - History of the Atom to 1925
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- 2555 - History of the atom after 1925
- 2349 - What happens when you cool an atom
- 1345 - Absolute zero temperature strangeness.
- 1072 - Boltzman’s Constant, Avogadro’s Number.
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- 505 - “How small is the Atom”
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- 983 - “How an Atom Works”
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- 985 - “Measuring How an Atom Works“.
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- 986 - “How a Molecule Works“.
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- 924 - “Rutherford’s Atom”
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- 727 - “Absolute zero”
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- July 6, 2021 TEMPERATURE - what it means to have one? 3213
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--------------------- --- Friday, July 9, 2021 ---------------------------
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