Month: February 2019

1848: Absolute Zero

Posted on by Dan

Everyone is familiar with the concept of temperature.  Temperature is a way to describe how hot or cold something is.  But what is it that determines how hot or cold something is?

All of matter is made of atoms, and those atoms are always moving.  Temperature then, is a measure of the kinetic energy (the energy of motion) of the particles in a substance or system.  The faster the atoms move, the higher the temperature.  Temperature also determines the direction of heat transfer, which is always from objects of a higher temperature to objects of a lower temperature.

Absolute zero is the lowest temperature theoretically possible.  It corresponds to a bone-chilling -459.67 degrees on the Fahrenheit scale and -273.15 on the Celsius scale.  At this temperature there is the complete absence of thermal energy, as the particles of a substance have no kinetic energy.

The History of Absolute Zero

The roots of the idea of absolute zero can be traced back to the early 17th century when scientists began to explore the behavior of gases.  In 1665, Robert Boyle formulated Boyle’s Law, which stated that the volume of a gas is inversely proportional to its pressure at a constant temperature.  This law laid the foundation for the study of gases and eventually lead to the concept of absolute zero.

Absolute Zero Temperature Scale
Absolute Zero Temperature Scale

Over the next 200 years additional discoveries were made that brought scientists closer and closer to the concept of an absolute zero temperature point.  Then in 1848 the distinguished British scientist, William Thomson (later Lord Kelvin), published a paper titled On an Absolute Thermometric Scale where he made the case for a new temperature scale with the lower limit to be absolute zero. At this time temperature was measured on various scales, such as Celsius and Fahrenheit scales.  However these scales had certain limitations and were based on arbitrary reference points.  Thomson recognized the need for a temperature scale that would provide a universal standard and be based on fundamental physical principles.  Scientists could now rely on a scale for temperature measurements without the need for using negative numbers.

Thomson’s key insight was to base his new scale on the behavior of an ideal gas.  According to Boyle’s Law, the pressure of an ideal gas is directly proportional to its temperature when the volume is held constant.  He realized that if a gas were to be cooled to a temperature at which its volume reached zero, then this temperature would represent the absolute zero of temperature.  Thomson correctly calculated its value and used Celsius as the scale’s unit increment.

Absolute zero is the temperature to which you all atoms would stop moving and kinetic energy equals zero. This temperature has never been achieved in the laboratory, but it’s been close. Sophisticated technology involving laser beams to trap clouds of atoms held together by magnetic fields generated by coils have cooled elements such as helium to within fractions of a degree of absolute zero.  The current world record for the coldest temperature is held by a team of researchers at Standford University in 2015. They used sophisticated laser beams to slow rubidium atoms, cooling them to an incredible 50 trillionth of a degree, or 0.00000000005 degrees Celsius, above absolute zero! This is extremely impressive since according to theory, it is suggested that we will never be able to achieve absolute zero.

Thomson’s temperature scale was later named the Kelvin Scale in his honor, and kelvin is the International System of Units (SI) base unit of temperature.

Practical Uses of Absolute Zero

The concept of absolute zero is relevant to many modern technologies, such as cryogenics and quantum computing.  Below is a summary of its applications:

  1. Cryogenics – cryogenics is the study of very low temperatures. cryogenics is the study of very low temperatures. Its technologies are used in various industries such as medical science, where they assist in the preservation and storage of biological materials.
  2. Superconductivity – superconductivity is the phenomenon where certain materials can conduct electric current with zero electrical resistance. Superconductivity is needed in several fields including medical imaging (MRI) and particle accelerator technologies.
  3. Quantum Computing – at very low temperatures quantum mechanical effects become more pronounced.at very low temperatures quantum mechanical effects become more pronounced. In order to create and manipulate qubits, the basic unit of quantum information, quantum computing systems require extremely low temperatures.
  4. Space Exploration – extremely low temperatures are encountered in deep space. Understanding the properties of materials at these temperatures is crucial for designing spacecraft components.

As you can see, absolute zero holds profound implications for various fields of study and cutting-edge technology.

Continue reading more about the exciting history of science!

Henry Cavendish

Posted on by Dan
Henry Cavendish portrait
Henry Cavendish

Henry Cavendish (1731 – 1810) was one of the great experimental and theoretical chemist and physicist of the 18th century.  So meaningful were his contributions to science that James Clerk Maxwell named the University of Cambridge’s physics laboratory in his honor after he founded it in 1874.

Henry was born in Nice, France, due to his family traveling at the time of his birth.  He was educated in a private school in London then attended the University of Cambridge in 1748 where he stayed for three more years.  His father, Lord Charles Cavendish, was involved with members of the Royal Society of London and took Henry to meetings in the last 1750s.  By 1760 Henry was became an elected member of the Royal Society and from there on lived a life dedicated to science.

His interest and achievements in science were vast and wide ranging.  He began his work at the Royal Society by heading a committee to review the society’s meteorological instruments.  This initiated his research in chemistry and in particular gas chemistry.  His is credited with being the first person to isolate hydrogen (which he termed “inflammable air”), to correctly calculate its density, and determine that it was contained in water in a two to one proportion.  As with most scientists of his time, Henry also experimented with electricity.  He wrote many papers on electricity for the Royal Society but most of his experiments did not become known until many years after his death.

He was known for his extremely careful and accurate measurements.  This quality came in handy when it came time for him to measure the composition of the atmosphere and the density of the Earth.  Both measurements he obtained compare very nicely with the values accepted today.

Henry Cavendish amassed incredible wealthy throughout his life.  He used his wealthy mainly in the pursuit of science as he was not very sociable.  It is thought that he had Asperger syndrome, a form of autism.  He died in 1810 as one of the wealthiest men in Britain.

Heinrich Hertz

Posted on by Dan
Heinrich Hertz
Heinrich Hertz

Heinrich Hertz (1857 – 1894) was a German who lived a short yet impactful life.  He was interested in meteorology and assisted in making advances in weather forecasting.  He also conducted groundbreaking research in electromagnetic waves, making him the first person to conclusively prove James Clerk Maxwell’s theory of electromagnetism.

Hertz was born in Hamburg into a wealthy and affluent family.  He showed early aptitude in the sciences and went on the receive his PhD from the University of Berlin in 1880.  He was able to study under the physicist and physician Hermann von Helmholtz, whom he became an assistant to in his post-doctorate studies.  In 1885, Hertz obtained a full time professorship at the University of Karlsruhe.

During his time studying at the University of Berlin Helmholtz encouraged the university’s Philosophy Department to offer a prize to anyone who could solve the problem of whether electricity moves with inertia.  Hertz showed that it did through a series of clever experiments and won the prize.  Impressed by his work and capabilities, Helmholtz then asked Hertz to compete for a different prize offered by the Berlin Academy: verifying Maxwell’s theory of electromagnetism.  He declined to work on this problem after he decided it would be too difficult and time consuming, instead electing to establish his reputation by doing work less tedious.

Six years later Hertz was working at the University of Karlsruhe and decided it was time to return to experimental physics. After several months of experiments some breakthroughs began to emerge.  In November 1886 Hertz devised an experiment in the effects of electromagnetic waves were observed.  They were originally called Hertzian waves, but were later renamed radio waves.  These experiments also allowed Hertz to report on the photoelectric effect which would soon be explained by Albert Einstein.

Hertz successful scientific career was cut short becoming very ill and eventually passed away at the age of 36. The SI unit for frequency – hertz – was named in his honor in 1960, replacing the term “cycles per second.”

1866: Laws of Inheritance

Posted on by Dan

The laws of inheritance are a set of fundamental principles that govern the transmission of genetic traits from one generation to the next. Its discovery and understanding have changed our view of life while having a profound impact on a diverse range of topics such as medicine, agriculture and biotechnology. The ideas behind the laws of inheritance, the theory of evolution by natural selection, and population genetics has formed what scientist’s call the modern synthesis, a cornerstone of modern biology.

Gregor Mendel and the Pea Plant Experiments

For most of history peoples understanding about inheritance came from anecdotal evidence and observations of certain traits being passed down from parents to offspring. It wasn’t until the mid 19th century that the Augustinian monk Gregor Mendel conducted his now famous experiments with pea plants that established the principles of heredity. Prior to Mendel’s experiments the prevailing theory of inheritance suggested a blending of traits and characteristics from both parents to their offspring.

Gergor Mendel's pea plant experiment (Credit: Encycleopedia Britannica)
Gergor Mendel’s pea plant experiment
(Credit: Encycleopedia Britannica)

In 1866 the Augustinian monk Gregor Mendel published Experiments in Plant Hybridization that explained his pea plant experiments and the resulting laws of inheritance.  His work was first read to the Natural History Society of Brünn then published in the Proceedings of the Natural History Society of Brünn. 

During the years 1856 to 1863 Mendel cultivated over 28,000 plants and tested for seven specific traits   The traits he tested for were:

  • Pea shape (round or wrinkled)
  • Pea color (green or yellow)
  • Pod shape (constricted or inflated)
  • Pod color (green or yellow)
  • Flower color (purple or white)
  • Plant size (tall or dwarf)
  • Position of flowers (axial or terminal)

The results of his careful experimentation allowed Mendel to formulate some general laws of inheritance. His three laws of inheritance are:

  • Law of Segregation – allele pairs (one form of a gene) segregate during gamete (sex cells: sperm or egg) formation. Stated differently: each organism inherits at least two alleles for each trait but only one of these alleles are randomly inherited when the gametes are produced.
  • Law of Independent Assortment – allele pairs separate independently during the formation of gametes.
  • Law of Dominance – when two alleles of a pair are different, one will be dominate while the other will be recessive.

Mendel’s laws of inheritance suggested a particulate inheritance of traits in which traits are passed from one generation to the next in discrete packets.  As already noted, this differed from the most popular theory at the time which suggested a blending of characteristics in which traits are blended from one generation to the next.

Unfortunately for the progress of science, Mendel’s work was largely unnoticed and forgotten during his lifetime.  This was for a few reasons.  First, he lived in relative isolation at the Augustinian St. Thomas’s Abbey, now the modern day Czech Republic, and did not have a network of scientific colleagues.  He published his work in relatively obscure scientific journal and did not have the means to promote his findings.  His work, in a sense, was also ahead of his time.  The scientific community was simply focused on other areas of study during his lifetime and the concept of discrete hereditary units (now called genes) did not fit in with the prevailing scientific paradigm.  Lastly Mendel did little follow up to his work and soon shifted his attention to administrative and educational duties within the abbey.  It wasn’t until the turn of the 20th century that his work was rediscovered and popularized independently by three scientists – Hugo de Vries, Carl Correns, and Erich von Tschermak.  

A Journey into Genetics

Mendel’s laws of inheritance laid the groundwork for the 20th century field of genetics.  The field of genetics is the study of heredity that incorporates the structure and function of genes as the mechanism of biological inheritance.  

The emergence of molecular genetics began to take shape after it was discovered that the mechanism of hereditary transfer was contained in nucleic acids.  The race was on to discover the mechanism by which nucleic acids transferred the hereditary material.  The final breakthrough culminated with the discovery of the double-helical structure of DNA by James Watson and Francis Crick in 1953, as it provided the definitive explanation for how genetic information is encoded and transmitted within living organisms.  

The field of genetics continues to advance into the 21st century at a blistering pace.  In addition to unraveling the fundamental principles of life, scientists are now able to exploit the mechanics of genes and are learning novel ways to edit them to cure disease.  As of late 2023, the United States Food and Drug Administration (FDA) and medical regulators in the United Kingdom have approved the world’s first gene-editing treatment for Sickle Cell Disease using a gene-editing tool called Crispr.  Crispr technology has the potential to revolutionize the field of genetics and various related fields through its precise genome editing capabilities, potentially leading to another exciting development in the exciting history of science!

Continue reading more about the exciting history of science!

Gregor Mendel

Posted on by Dan
Gregor Mendel portrait
Gregor Mendel

Gregor Mendel (1822 – 1884) was a German-speaking, Augustinian monk who did pioneering work on genetics.  His claim to fame however, was posthumous.  Mendel’s initial work was more or less unknown while he was alive and went unnoticed until it was rediscovered 50 years after death.

Mendel was born in the Austrian Empire in what is now present day Czech Republic.  During his childhood he worked on the family farm until he was sent to school at age 11.  However money was tight for him and his family and financial struggles weighted on his decision to join the monastery.  He joined the Augustinian Saint Thomas’ Abbey in Brünn and began his theological studies.  Mendel was always interested in more than just is theological studies and under a sponsorship he sent to study for two years at the University of Vienna to receive a broader education in the sciences.

When Mendel returned from the University of Vienna he began to carry out experiments on plants in the monastery’s experimental gardens.  He chose the common pea and began his experiments in 1856.  He identified seven traits that seemed to be inherited independently of other traits.  Mendel tested over 28,000 pants in the eight years of experimentation and was able to generalize a few laws of inheritance from his results.

His first law, the Law of Segregation, states that allele pairs (one form of a gene) segregate during gamete (sex cells: sperm or egg) formation.  Stated differently: each organism inherits at least two alleles for each trait but only one of these alleles are randomly inherited when the gametes are produced.  His second law, the Law of Independent Assortment, states the allele pairs separate independently during the formation of gametes.  His third law, the Law of Dominance, states that when two alleles of a pair are different, one will be dominate while the other will be recessive.

Mendel did various other experiments in biology and in other areas of science but the burdens of his administrative duties became too great and he stopped going his scientific studies.  He presented his work a handful of other people but nobody at the time realized the significance of his work.  The conventional wisdom was that there was a general blending of heritable traits rather than Mendel’s particulate inheritance of traits, where traits are passed in discrete packets.  Mendel’s work was rediscovered by three botanists each working independently in 1900 – Hugo DeVries, Carl Correns and Erich von Tschermak.  They gave priority to his work as well as confirmation to their own research.