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The Drinking Bird as a Heat Engine

The drinking bird is a nice example of a heat engine. The evaporation of water at the bird’s beak results in a cooler temperature there than at its base (around the tail feather). In turn, this temperature difference causes a pressure difference (high to low from base to beak) that causes the (very volatile) liquid to rise up, eventually toppling the bird forward causing it to “drink”.

The Drinking Bird

Cooling Soup

Cooling soup by blowing on a spoonful prior to placing it in your mouth works because the hotter atoms are literally blown away.  This is because the soup is made up of atoms comprised of a range of speeds. The atoms with the higher speeds – the hotter ones – are on top, hovering above the atoms with the lower speeds – the cooler ones. So, the end result of blowing on the spoonful of soup is that the hotter atoms are blown away, while the cooler ones are left behind.

Maxwell, the Rings of Saturn and Kinetic Theory

In 1855, Maxwell devised a theory that correctly predicted the composition of the rings of Saturn. While at Aberdeen, Maxwell devoted much of his time to the problem and in a letter to Thomson describes the rings as:

“… a great stratum of rubbish jostling and jumbling round Saturn without hope of rest or agreement in itself …”

Maxwell constructed a theory that showed Saturn’s rings couldn’t be solid, liquid or gas, but rather were made of many small, solid, colliding particles orbiting the planet, which were dynamically stable and provided a solid-like appearance; the solution won him the prize. Today, we do know that Saturn’s rings are comprised of tiny rocks that collide with each other as they orbit the planet. In is interesting to note that what led Maxwell to kinetic theory was, oddly enough, Saturn’s rings.

Galileo and The Telescope

By mid-1609, Galileo was working on his treatise about the science of motion, when upon hearing of the invention of the spyglass (the precursor to the telescope) he dropped everything to make his own version. By the end of August, Galileo had a 9X telescope. Around December 1, 1609, Galileo had in his possession a 20X telescope, allowing him to observe the moon’s rough mountainous surface, four (of the currently sixty-seven known) moons of Jupiter, and several new stars.

Galileo, Professor at Pisa

In 1589, Galileo became professor at the University of Pisa making half of his predecessor’s final salary.

Atomic Weight

The atomic weight of a mid-sized atom is around 0.00000000000000000000001 grams; a 1/400th of an inch grain of sand weighs about 0.001 grams.

Earth’s Atmosphere

Earth’s atmosphere is 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.039% carbon dioxide, and small amounts of other gases.

The Mechanical Philosophy

The notion that the universe runs like a mechanical clock arose in the 17th century leading to the mechanical philosophy.

Newton’s Intervening God

While Newton saw the world as following definite laws, he also imagined an intervening God to keep things running smoothly.

Galileo’s Distraction

In mid-1609 Galileo turned his focus away from the laws of motion and pointed his telescope towards the sky.

Pendulum and Small Swings

A pendulum goes to and fro in the same amount of time regardless of how big the swings are – only when the swings are small.

Bose-Einstein Condensation and Quantum Entanglement

In 1925, Einstein predicted a very unusual phase transition that occurs for the quantum ideal gas. Einstein describes the phenomenon in a letter to Paul Ehrenfest (1880–1933):

“From a certain temperature on, the molecules ‘condense’ without attractive forces, that is, they accumulate at zero velocity.”

In other words, as the temperature is lowered, the atoms in the gas begin to “pile up” or condense into the lowest (single particle) energy state, which is the one with zero kinetic energy; there’s a critical temperature whereby a phase transition (now called (Bose-Einstein condensation) occurs. This effect becomes most pronounced as the temperature is lowered to absolute zero, at which point, all the gas atoms condense into this lowest energy state. This phenomenon is an example of quantum entanglement.

Energy vs Momentum Conservation

Hints of energy being conserved, much like momentum, were showing up by the 1840s. But unlike momentum conservation, which by comparison was quickly accepted and understood (pretty much by 1687 with Newton’s Principia), energy conservation remained a mystery until 1850.

Heat is “Motion”

In 1798, while boring holes into cannon barrels (as part of the manufacturing process), Count Rumford concluded that heat was the result of some sort of motion within objects.

Descartes’ Conservation of Motion

In 1644, in his Principles of Philosophy, René Descartes (1596-1650) proposed that the total motion of the universe is conserved. While this conservation of motion concept bears a certain similarity with Newton’s conservation of momentum, it’s still wrong.

Galileo’s New Title

Unhappy with his arrangement at University of Padua, Galileo managed to strike a new deal in 1610 whereby he became “Chief Mathematician of the University of Pisa and Philosopher and Mathematician to the Grand Duke of Tuscany”. The appointment was for life and he wasn’t obligated to teach at the university. He also wasn’t required to reside in Pisa, which allowed him to finally return to his beloved Florence.

Galileo’s Private University

In 1599, Galileo acquired a large house with a garden and vineyard. Here he housed students who stayed with him for extended periods (along with their servants), and maintained a workshop (complete with a coppersmith) for the manufacture of instruments. The private lessons he gave along with his university courses kept Galileo very busy.

Feynman on Energy

“It is important to realize in physics today, that we have no knowledge of what energy is … It is an abstract thing in that it does not tell us the mechanism or the reasons …”

Photon Momentum

In 1905, Einstein said light is a particle (photon) with energy proportional to its frequency. Although photon momentum was known much earlier to Einstein, he waited until 1916 to finally declare it.

The Imponderable Fluids

By the end of the eighteenth century, heat along with its cohorts light, magnetism and electricity were regarded as an imponderable fluid capable of flowing between the spaces assumed to be present in matter.

Lavoisier on Constant Mass

In 1789, Lavoisier showed that the total mass during the course of a chemical reaction is unchanged. Rather the atoms simply “reorganize” themselves, kind of like the reshuffling of deck or cards.

Lavoisier’s 33 Elements

In 1789, Lavoisier published An Elementary Treatise on Chemistry where he describes 33 elements. The list begins with caloric and continues with light, oxygen, nitrogen and hydrogen.

Heat as “Caloric”

Pierre-Simon Laplace (1749-1827) imagined heat to be a fluid composed of particles, deemed by Antoine Lavoisier (1743-1794) as “caloric”.

Entropy and Atoms

Our understanding of the connection between entropy and the microscopic world of atoms is mostly due to the work of James Clerk Maxwell and Ludwig Boltzmann.

Clapeyron’s Reformulation of Carnot’s Work

In 1834 Émile Clapeyron (1799-1864), a former classmate of Carnot’s, published a paper in the Journal de l’École Polytechnique. Here he reformulated Carnot’s work using clear concise mathematics and a new graphical presentation for Carnot’s reversible heat engine (still taught today to every chemistry major taking a good physical chemistry class) that finally brought Carnot’s work to the attention of engineers, chemists and physicists.

Energy and Entropy

Energy and the first law that governs it can’t explain why certain processes tend in what apparently is a favored direction; for that we need entropy.

Einstein and The Quantum Ideal Gas

In 1925, Einstein made his last contribution to quantum theory (consider by many to be his last significant scientific contribution as well) with his work on the quantum ideal gas.

Clausius Discovers Entropy

Clausius formulated much of the original ideas of his theory on entropy in 1854. However, it wasn’t until 1865 that he actually named his new property “entropy”.

Energy, Entropy and the Universe

Whereas the universe keeps energy at a constant (energy is conserved), it continues to increase the entropy. Therefore, no process that occurs will ever result in an overall decrease in the entropy of the universe. The universes’ tendency of maximizing entropy is reminiscent of “a universal tendency to the dissipation of mechanical energy” as stated by Thomson, and Clausius noted the connection.

Galileo and Two New Sciences

In 1634, Galileo, now under guarded house arrest, and mourning the recent death of his beloved daughter, returned to his project of some twenty-five years prior to produce his final masterpiece Discourses on Two New Sciences.

Sound Waves, Diffraction, and Propagation

A sound wave will often travel from one room to another spreading out though an adjacent doorway where it’s then heard. This is an example of the wave property known as diffraction.

Newton Waited to Publish Opticks

In 1666, Newton bought his first prism with the motivation of disproving Descartes wave theory of light. In 1672, he gave a brief account of his findings, in the form of a letter, to the Royal Society, whereby – after a bit of convincing – it was published in the Philosophical Transactions of the Royal Society. Although not unanimous, Newton’s work met with much praise. However, one critic’s words would resound with Newton, thus beginning a lifetime feud.

Robert Hooke (1635–1703), who was considered the expert on the subject in England, sent a lengthy critique. In short, it pretty much said Hooke had performed all the same experiments, drawn different conclusions, and that Newton was outright wrong. In 1704, Newton finally published a full account of his theory of light in Opticks. To be sure, Newton had already drafted a treatise covering much of this work by 1672,

The Maxwell Distribution

Not all the atoms in a gas move at the same speed, but rather each atom takes on a speed lying in a specific range. For an ideal gas at equilibrium, this range is known as the Maxwell distribution. In 1860, Maxwell needed merely a single page to derive this amazing result, which also allowed him to calculate other important properties of a gas that matched with experimental observation.

Heat is Energy

Heat was the biggest stumbling block to a complete understanding of energy, remaining separate from it until around 1850 when the first law of thermodynamics was inducted.

Confusion About Energy

An understanding of energy in its entirety did not occur until well into the nineteenth century.

Particles in Motion

That the properties of gases could be explained by particles in motion had been advocated in 1738 by Daniel Bernoulli (1700-1782), who proposed a model that is very similar to the one in acceptance today.

The First “Atomic Theories”

The first “atomic theories” focused on a “primary element” responsible for creating all other matter. Heraclitus said it was fire, Thales of Miletus (c.624 BC–c.546 BC) said it was water, Anaximenes (c.585 BC–c.528 BC) thought it was air, and Empedocles finally unified these declaring there to be the four elements of air, earth, fire and water. Later Aristotle adopted Empedocles’ four elements and so it remained up until about the 17th century.

Particle, Corpuscle, Element and Atom

Through the 18th century the words particle, corpuscle, element and atom were all used synonymously to refer to the building blocks of matter. In fact, no more insight into what an atom was had been accomplished since (the Greek philosopher) Democritus’ description some two thousand years prior.

Collisions in a Gas

The particles (atoms, molecules) of a gas move farther and faster (in a given interval of time) than those of a liquid. As they do so, a single particle undergoes about a billion collisions every second with other particles.

Waves and Diffraction

A lower pitch sound, that is a sound wave with a longer wavelength (lower frequency), will diffract (or bend) around an object more than a higher pitch sound (a sound wave with a shorter wavelength and higher frequency). This means a lower pitch sound is more easily heard around an object that may be in front of the source of the sound than a higher pitch sound

Einstein’s Light Quanta Hypothesis Explains Physical Phenomenon

In his1905 paper, On a Heuristic Point of View Concerning the Production and Transformation of Light, Einstein showed how his newly introduced light quanta hypothesis could be used to interpret several well-known experimental observations, the most notable of these phenomena being the photoelectric effect.

Einstein’s Photon

The major theme of Einstein’s 1905 paper, On a Heuristic Point of View Concerning the Production and Transformation of Light, was that light (under certain circumstances) behaves as if it’s comprised of individual particles rather than waves. These particles, or “chunks” of light were originally called light quanta, and then later came to be called photons.

Einstein’s Light Quanta Hypothesis and The Nobel Prize

It was the first of Einstein’s 1905 papers, On a Heuristic Point of View Concerning the Production and Transformation of Light, which he referred to as “very revolutionary” – the only time he would ever say this about any of his work, in fact – and which, in part would win him the Nobel Prize in 1921.

Atomic Energy States are Discrete

The energy states available to atoms and molecules occur at specific intervals. In other words, they are discrete rather than continuous.