Temperature by definition is a measure of how something is cold or hot but due to the
lack of scientific consistency in the terms “cold”
or “hot” we use temperature with different scales to
describe the thermodynamic state of any object.
In particular, temperature is a measurement of
the average kinetic energy of the particles at the molecular and atomic levels of an object,
that is the type of energy corresponding to the
motion of these particles.
The faster these particles move, the more kinetic energy they have.
Furthermore, these particles are constantly colliding
with each other resulting in many variations in the kinetic energy associated with each
particle therefore we take the average kinetic energy
of the total number of particles to avoid such
variations.
On being familiar with the concept of temperature, you may wonder what makes
objects hot and what makes them cold; in other words the limit between the cold and the hot
and based on what foundation we constructed such a limit?
In order to demonstrate that limit, scientists came up with two terms; the “absolute hot”
which is the upper limit of the highest temperature
that is possible in the entire universe and the
“absolute zero” which is the lowest temperature ever at which the particles at the atomic
level stop moving and lose their vibrational motion
hence their kinetic energy.
Driven by the “Embrace the Extremes” principle, in this video;
we’re introducing the most extreme temperatures in the
universe both observed and man made.
Passage 1 Here’s the list from hottest to coldest
temperatures: 10- The highest possible theoretical temperature
ever is the Planck temperature which is of order 10^(32) Kelvin.
it was the temperature of the universe 10^(-43) seconds after the moment
of the big bang, the big bang model states that our universe at its beginning, 13.7 billion
years ago, was in extremely hot and dense state
which motivated the development of the standard model of strong and electroweak interactions
not to mention the extending and expanding the
original big bang model, where the fundamental particles including the quarks and leptons
as point like particles.
Consequently, the early universe can be pictured as a dilute gas of weakly
interacting quarks, leptons and gauge bosons.
9- The hottest handmade temperatures ever, have been achieved by the physicists at CERN’s
large hadron collider near Geneva, Switzerland.
They recorded 5.5 trillion Kelvin by colliding Lead ions to momentarily create a quark-gluon
plasma which is pretty much like a subatomic plasma that is thought to have existed just
moments after the big bang.
The experiment was performed by by the ALICE collider in 2012,
by these results the physicists were able to create a
quark-gluon plasma that is 38% hotter than the Guinness record holder; the 4 trillion
Kelvin plasma achieved in 2010 by a similar experiment
at the RHIC, Brookhaven New York.
The ability to achieve such high temperatures
enables the physicists to map the early stages of our
universe through tracing the phase transitions of the quark-gluon plasma.
8- The core temperature of a dying massive star comes in the third place with approximately
10 to 100 billion Kelvin.
As you probably already know, the star is a sphere of gas held together by
its own gravitational pull; its life is considered as a constant struggle against this gravitational
pull.
Since gravity is constantly trying to cause the star to collapse.
However, it’s not the only force acting on the star during its lifetime;
the star’s core is extremely hot and radiates heat from
the hydrogen fusion into helium which results in the radiation pressure that pushes outwards
counteracting the force of gravity and putting the star in a state of hydrostatic equilibrium.
Most of the star's lifetime is called the main
sequence stage at which there’s an equilibrium between
the gravitational pull acting inward and the radiation pressure acting outward.
During the main sequence, the heat and radiation come from
the nuclear reactions at the core, but eventually the
core runs out of its hydrogen fuel and transitions into other stages provided that the star is
massive enough to go through some other nuclear reactions.
At first, the outer layers will swill out into a red supergiant.
Next, the core will shrink as it becomes more dense and hot.
Then, the helium fusion into carbon will begin and
it will shrink again once it runs out of its helium fuel,
the massiveness of the core will allow for the carbon fusion into neon.
Eventually, it will undergo several nuclear reactions until the core is
filled up with iron atoms.
The previous reactions were exothermic that resulted in heat and radiation,
however the iron fusion reaction is endothermic that requires energy input in order to occur.
Which means that a core filled up with iron atoms
will lose its fight against gravity since there will be no longer a radiation pressure,
induced by the core reactions, pushing outward.
The gravitational pull will crush the iron atoms together raising
the core’s temperature to approximately 100 billion Kelvin and there will be a repulsive
force between the nuclei overcoming the gravitational
pull, eventually there will be a great explosion known as the supernova.
About 75% of the star’s mass is ejected into space during the
supernova and the fate of the leftover is determined by the star’s original mass.
Whether a neutron star or a black hole.
7- The highest temperature in our solar system is the internal temperature of the sun which
is approximately 15.7 million Kelvin.
It's important for you to know this due to the significance of
the sun’s role in the evolution of life on our planet.
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Passage 2 6- The coldest temperature in the solar system,
38 Kelvin, was measured in 1989 by Voyager II
on the surface of Triton which is the one of Neptune’s moons and it’s barely chilly
by comparison to other coldest temperatures.
Additionally, the coldest temperature ever recorded
on earth is approximately 184 Kelvin, it was recorded at the Soviet Vostok station in Antarctica
on 21st of July 1983 by ground measurements.
5- The temperature of the cosmic microwave background is about 2.74 Kelvin which is
considered one of the coldest temperatures on the cosmological scale.
The formation of the CMB radiation was an extremely complex process.
100,000 years after the big bang, the recombination era began; in that era the universe
temperature was cool enough for the free nuclei and electrons to combine and form atoms.
Before the era of recombination the universe was opaque to any form of electromagnetic
radiation, even light, due to the large number of free
electrons.
Although the universe was a coupled state of photons and baryons and there were
approximately 10^6 photons for every electron, no photon was safe from being scattered by
the free electrons.
The Baryon-Photon plasma enjoyed three profound differences between the
behaviour of matter at this state compared to the gentle gas nebula of the modern universe.
First, the baryon photon plasma was opaque since there exist no lines of sight to anything
during that time.
Second, light was able to exert an enormous amount of pressure on this
plasma leading to the production of the colossal sound waves.
And third, those sound waves travelled very fast at approximately half
the speed of light.
The baryons underwent a phase transition from a baryon photon plasma to
a gas.
This phase transition is called recombination, while free electrons are able to interact
with any frequency of light the electrons bound into
atoms are restricted to only those specific frequencies corresponding to the energy level
transitions of that atom.
Consequently, light and matter decoupled and the universe went from
opaque to transparent over several thousand years.
As the wave of plasma and photons decoupled, light began to stream freely through
the universe as the cosmic background radiation.
However, the plasma, which is now hydrogen and helium gas, stalled and the speed
of the sound dropped from half the speed of light to only hundreds of meters per second.
The wave of the plasma-turned gas essentially froze in its current state.
The radius of that shell became fixed to the rate of the universe’s
expansion itself.
Moreover, the exact distance that sound could travel over the age of the universe
at that time is known as the sound horizon.
At the time of the Recombination era, the sound
horizon was around 500,000 light years.
4- The bulk Aluminum metal turns superconductive at approximately 1.2 Kelvin;
superconductivity by definition is the ability to transmit electricity without any resistance
which means that no energy loss during the transmission
process.
The resistance is the main reason that electrical gadgets like laptops or even
smartphones heat up when leaving them on for a
long time; the electricity meets resistance as it courses the machine circuits resulting
in heat which is a form of energy loss.
The good news is that It might not be the case in the future as a
team led by Vitaly Kresin, professor of physics at the university of southern california USC,
found that Aluminum superatoms form pairs of electrons at temperatures around 100 Kelvin.
In order to fully understand this, you may need
to know that superatoms are homogenous clusters of atoms and the cooper pairs are two electrons
that attract one another in some materials under certain conditions such as extreme low
temperatures and they were first predicted by
Leon Cooper in 1956.
The superconductivity is measured by the ability of these materials to
form Cooper pairs and according to professor Kresin, this may be the discovery of a new
family of superconductors and raises the possibility
that other types of superatoms will be capable of
superconductivity at even warmer temperatures.
It might be a matter of time before discovering superconductors at the room temperature, can
you imagine what will be the implications of this
discovery?!
If superconductors can be harnessed, they will totally transform the world.
For instance, they will increase the power of computers while reducing
the cost of electricity and the emission of greenhouse gases.
They will provide a fuel-free transportation system, and an alternative way of
screening the human body without the use of dangerous X-rays.
3- The coldest known natural temperature in the universe is 1 Kelvin; the temperature
of the Boomerang Nebula which is about 5,000 light
years from Earth in the direction of the southern constellation Centaurus.
It was first identified by australian astronomers in 1979, its name is
derived from symmetry of its structure as seen from ground-based telescopes as it looks
like a boomerang or more possibly a bow tie.
There’s a dying star that’s three times heavier than our
own Sun at its core.
furthermore, for the last 1500 years, the nebula has been spraying out gas
at a speed of more than 300,000 mph.
That gas squeezed out of the nebula is approximately 1
Kelvin which is the lowest natural temperature so far recorded.
2- The lowest coldest man-made temperature ever recorded has been achieved by the
researchers of the YKI group of the low temperature laboratory in Otaniemi, Espoo, Finland.
The record low temperature was reached in a piece of rhodium metal, which was cooled
to 100 pK or Pico Kelvin.
However, the main objective of these experiments was not the sole purpose
of achieving the record low temperature but to study the magnetism of the nuclei of the
rhodium atoms.
Each of the billions of nuclei in rhodium has a magnetic moment like a small compass
needle.
And by lowering the temperature, researchers expected the moments to “freeze” based
on similar ultra-cold experiments that were performed with other elements such as copper
and silver.
Unexpectedly, the rhodium atoms did not “freeze” even at this record-low temperature.
1- The coldest possible theoretical temperature ever is the absolute zero or at 0 Kelvin,
it’s the lowest possible temperature where nothing
could be colder and no heat remains in a substance.
It’s the point at which all the fundamental particles have zero vibrational motion hence
zero kinetic energy.
Thanks for watching everyone!
Do you think it’s possible to reach superconductivity at high temperatures?
Can you think of other applications of superconductors in our
daily life?
Can you guess the fate of the dying star at the center of the Boomerang Nebula?
Did you learn anything new in this video?
Please let me know in the comments below, be sure to
subscribe, and I’ll see next time on the channel!