- 4049 - QUANTUM TEMPERATURES? What Happens When You Cool an Atom? Getting to the very small enters the Quantum World where physics takes on strange behavior. But, also, getting to the very cold enters the same unusual world of Quantum Mechanics. Today science is exploring more of this world near temperatures of Absolute Zero, (-273 degrees Centigrade).
---------------------------- 4049 - QUANTUM TEMPERATURES?
- From the point of view of physics temperature
is a measurement of the average Kinetic Energy of atoms. We call it “Thermal Energy”. It is the average momentum and velocity of a
bunch of atoms. As you heat up any
material its atoms vibrate and oscillate faster. The hotter it gets the faster they oscillate.
-
- At some point, when certain materials reach
a specific temperature the oscillating atoms will break bonds and change
states. Ice will turn into water and
water will turn into steam. The matter
expands as the faster oscillating atoms require more space.
-
- Kinetic Energy is the product of momentum
and velocity. Momentum is the product of
mass and velocity. Therefore, the
Kinetic Energy of the atoms is their mass times their velocity squared, ( KE
= m*v^2 ).
-
- The opposite is happening when a material
cools down. The vibrations slow and the
average Kinetic Energy goes down as the temperature declines. The colder it gets the slower the atoms vibrate. There is a point where atoms slow down to
where they come to a complete stop. This
point is called Absolute Zero, zero degrees Kelvin, - 273 degrees Centigrade.
-
- Near Absolute Zero is where we enter the
Quantum world and we learn that atoms
and their fundamental particles never really stop. There is Zero Point Energy and the classical
Kinetic Energy calculations say zero.
However, we must use the new math of Quantum Mechanics to understand the
behavior of sub-atomic particles as they approach Absolute Zero temperature.
-
- Particles have on positions at the sub-atomic
scales. They are oscillating waves. And,
Energy is not continuous. It comes is
small bundles, or quanta of energy. This
quanta ,or fundamental limit of how small energy bundles can be, is called
Planck’s Constant of Action. It is equal
to 6.626 * 10^-34 kilogram * meters^2 / second.
-
- This is a very small number. At the smallest scales of the oscillating
particle / wave dualities, these bundles of energy are still oscillating even
at the temperature of zero Kelvin. As
the temperature lowers you remove energy until you can not remove anymore. Physics is getting so close to this limit
they no longer use degrees Kelvin as the measurement. They use the number of Quanta that are left
to be removed.
-
- To better understand Planck’s Constant of
Acton, symbol “h”, let’s define the meaning of Action.
-
-------------------- Momentum is the product of Mass and
Velocity, ( p = m * v ), kilograms * meters / second
-
-------------------- Kinetic Energy is the product of Momentum and Velocity,
(
KE = m * v^2) , kilogram * meters^2 /
seconds^2.
-
-------------------- Action is the product of Energy, or Work, and
Time, ( A = E * t ) , kilogram * meters^2
/ second.
-
------------------- Planck’s Constant of Action, ( h = 6.626 * 10^-34 kilogram * meters^2 / second
).
-
- The vibration
energy of the Quanta is the 'Constant of Action' divided by time.
Energy = Action / time, ( E = A / t ). The frequency of vibration is cycles of waves
per second. Frequency = 1 / time,
( f = 1/ t) . So, another way to
show the formula for Energy is as the product of Action and Frequency, ( E = h * f ). Lowering the temperature lowers the energy
and therefore lowers the frequency of vibration.
-
- So, the way to visualize this is the
oscillating Quanta of Energies are moving back and forth in an oscillating
wave. As the temperatures get lower,
Energy is removed, and the energy packets in the waves move back and forth at
an ever slower rate.
-
- Physics laboratories around the world are
getting ever closer to the slowest rate possible. It is called the Ground State of Absolute
Zero. Here is a summary of how close
labs have gotten this measurement. Note
that at every lower temperatures the measurements are in Quanta instead of
Kelvin:
-
------------------------ U.C.
Santa Barbara
--------------- 0.000135 Kelvin
-
------------------------ Yale University -------------------- 0.0000682 Kelvin
-
----------------------- Swiss Federal Institute ------------
63 Quanta
-
---------------------- Cal Tech University ---------------- 4 Quanta
-
---------------------- National Institute of Standards ----- 1 Quanta
-
- The challenge for the labs now is how long
they can keep the temperatures at this level so they can study the quantum
affects. To date the Ground-State
lifetimes are only lasting from 6 nanoseconds to 100 microseconds. How the labs are achieving these temperatures
is a whole other story. If you want to
learn. They are using lasers to dampen the
Quantum oscillations.
-
-
June 11, 2023 QUANTUM TEMPERATURES? 1254
4049
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--------------------- --- Sunday, June 11, 2023 ---------------------------------
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