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”.
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.
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.
The story of Galileo dropping objects from the Tower of Pisa probably never happened.
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.
In 1589, Galileo became professor at the University of Pisa making half of his predecessor’s final salary.
Earth’s atmosphere is 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.039% carbon dioxide, and small amounts of other gases.
The notion that the universe runs like a mechanical clock arose in the 17th century leading to the mechanical philosophy.
While Newton saw the world as following definite laws, he also imagined an intervening God to keep things running smoothly.
Galileo was an accomplished lute player and often played duets with his father.
In mid-1609 Galileo turned his focus away from the laws of motion and pointed his telescope towards the sky.
Galileo put his original work on the laws of motion on hold for 25 years to focus on his passion with astronomy.
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.
Although he bragged of having designed one, Galileo never made a pendulum clock. His son did after Galileo died.
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.
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.
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.
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.
Proposed in 1811, Avogadro’s Hypothesis only began to gain acceptance in 1858 (two years after his death) thanks to Stanislao Cannizzaro.
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.
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.
“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 …”
Galileo’s natural music ability helped him measure time in his experiments with the inclined plane.
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.
Despite the various subatomic particles comprising an atom, only its outermost electrons are involved in chemical reactions.
“If all this damned quantum jumping were really here to stay, I should be sorry I ever got involved with quantum theory.” –Schrödinger
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.
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.
Pierre-Simon Laplace (1749-1827) imagined heat to be a fluid composed of particles, deemed by Antoine Lavoisier (1743-1794) as “caloric”.
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.
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.
Being able to read Maxwell’s work on electromagnetic theory motivated Boltzmann to learn English.
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.
The Greek philosopher Anaxagoras considered matter to be infinitely divisible.
After 1925, Einstein turned his back forever on quantum mechanics, arguing that its probabilistic nature was a fundamental flaw.
If in 1917 Einstein truly saw the probabilistic nature as a shortcoming, later he would be less forgiving.
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.
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.
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.
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,
A long time proponent of atoms, Boltzmann died unaware of Einstein’s landmark 1905 paper, which proved their existence.
The Maxwell distribution was the first time a physical process was described as a statistical/stochastic phenomenon.
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 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.
An understanding of energy in its entirety did not occur until well into the nineteenth century.
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” 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.
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.
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.
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 1905 paper, On a Heuristic Point of View Concerning the Production and Transformation of Light is often (wrongly) referred to as his paper on the photoelectric effect.
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.
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.
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.
At the atomic level, energy occurs as “chunks” or quanta.
Transitions between the energy states of atoms and molecules require a specific amount of energy, nothing more, nothing less; it’s only these particular values that are allowed by nature.
The energy states available to atoms and molecules occur at specific intervals. In other words, they are discrete rather than continuous.