On This Day in Science History - September 21 - Bubble Chambers

September 21st is Donald Glaser's birthday. Glaser is an American physicist and neurobiologist who was awarded the 1960 Nobel Prize in Physics for the invention of the bubble chamber.

The bubble chamber is a detection device for particle physics that works on the same basic principle as the cloud chamber. A vessel is filled with a transparent liquid (usually liquid hydrogen) heated to just below its boiling point and aligned with a magnetic field. When the scientist is ready to take a reading, a piston is used to expand the chamber. This causes the liquid to become superheated. Any charged particles passing through the vessel will ionize the liquid and cause bubbles to appear along the particle's path. The bubble density and path shape can give information on the type, charge and lifetime of the particles.

Bubble chambers have been replaced by newer methods of detection in modern particle research laboratories, but they still have a place in demonstrations and education. The photographs taken of bubble trails bring the invisible world of particle physics to a light a student can see, measure and understand. Find out what else occurred on this day in science history.

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On This Day in Science History - September 20 - AAAS Birthday

September 20th is the birthday of the American Association for the Advancement of Science. The AAAS is an international non-profit organization that promotes scientific understanding, freedoms, responsibility and education. It also publishes one of the most read scientific journals in the world. Science is a weekly peer-reviewed scientific journal with a subscription base of 130,000 readers.

The AAAS was formed in Pennsylvania from the Association of American Geologists and Naturalists in 1848 with the goal of being able to respond to the increasing rapid pace of scientific progress and discovery.

Happy Birthday AAAS and find out what else occurred on this day in science history.

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This Day in Science History - September 18 - Space Tortoises

September 18, 1968 is the day the Soviet space probe, Zond 5 became the first spacecraft to fly around the moon and return to Earth. It was designed to launch from Earth orbit, reach the moon and return as a precursor to a possible manned mission. Besides taking photographs of Earth and the Moon, the probe carried a biological payload of insects, bacteria, plants and two Russian steppe tortoises. The Zond 5 returned to Earth to splash down in the Indian Ocean. The probe was recovered and the tortoises survived. They lost some weight and the trip did not affect their appetite.

These tortoises were the first tortoises in space and also became the first tortoises to fly around the Moon. Find out what else occurred on this day in science history.

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On This Day in Science History - September 15 - Butlerov and Chemical Structures

September 15th is Aleksandr Mikhaylovich Butlerov's birthday. Butlerov was the Russian chemist who established the first modern theory of chemical structure. He believed a molecule's nature is determined not only the type and number of atoms, but their arrangement and relationship to each other. He demonstrated the existence of isomers where molecules could have the same molecular formula, but different structures. He also was the first to recognize some organic compounds contain double bonds.

Butlerov was also the first to produce formaldehyde. Formaldehyde (CH2O) is the simplest aldehyde and is used as a basic building block in several organic chemical syntheses. It is also used as a stabilizer in photography and histology and as a biocide to kill bacteria and fungi.

Find out what else occurred on this day in science history.

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On This Day in Science History - September 16 - Fahrenheit

September 16th marks the passing of Gabriel Fahrenheit. Fahrenheit was a German physicist who invented the alcohol and mercury thermometers. He is also the person responsible for the Fahrenheit temperature scale.

The Fahrenheit scale was originally calibrated to three points. The first point was set at 0 °F and measured from the lowest temperature of a mixture of water, ice and ammonium chloride at equilibrium. The second point was measured when still water would start to form ice on its surface and assigned the value of 32 °F. The third point was set to 96 °F and is recorded by measuring the temperature of a person when the thermometer is held under the armpit or under the tongue. He designated the interval of a degree Fahrenheit to correspond to 64 degrees between the second and third point. This made marking his thermometer easy since he could bisect the interval between the two values six times.

Scientists later observed that water would boil at nearly 180 degrees above its freezing point. The scale was modified to make this value exactly 180 degrees. This set the temperature of water to 212 °F. This slight alteration moved the body temperature reading to 98.6 °F that we know today.

Find out what else occurred on this day in science history.

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On This Day in Science History - September 13 - Hans Gram

September 13th is Hans Christian Joachim Gram's birthday. Gram was a Dutch bacteriologist who discovered a staining technique used in histology and microbiology. The Gram stain test is generally the first test microbiologists perform when identifying bacteria. It quickly divides the bacteria into two types: Gram positive and Gram negative. When the Gram stain is applied, the Gram positive bacteria will absorb the stain and turn purple. The Gram negative bacteria will not absorb the stain and may be colored pink using a counterstain.

Find out what else occurred on this day in science history.

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On This Day in Science History - September 14 - Charles du Fay's Birthday

September 14th is Charles Fran?ois de Cisternay du Fay's birthday. He was French scientist who discovered there were two types of electrical charge: vitreous and resinous. We know them as positive and negative today. He named his charges after the methods he used to generate the charge. Vitreous (Latin for glass) electricity is generated when glass is rubbed with fur. Resinous (Latin for resin or amber) electricity is obtained from rubbing amber with silk or paper. He also noticed the different charges would attract each other, but the same kind of charge would repel each other. He developed a theory to explain this behavior where there existed two different fluids. Neutrally charged objects would have equal amounts of both fluids which would neutralize each other. When rubbed, an object would lose one of these fluids and leave an excess of the other. Today, we know the transfer of electrons is involved in this behavior, but it helped usher in a new study in science. Find out what else occurred on this day in science history.if(zs>0){if(zSbL250)gEI("spacer").style.height=Math.floor(e[0].height/12)+17.5+'em';else{var zIClns=[];function walkup(e){if(e.className!='entry'){if(e.nodeName=='A'||e.style.styleFloat=='right'||e.style.cssFloat=='right'||e.align=='right'||e.align=='left'||e.className=='alignright'||e.className=='alignleft')zIClns.push(e);walkup(e.parentNode)}}walkup(e[0]);if(zIClns.length){node=zIClns[zIClns.length-1];var clone=node.cloneNode(true);node.parentNode.removeChild(node);getElementsByClassName("entry",gEI("articlebody"))[0].insertBefore(clone,gEI("spacer"))}}}};zSB(2);zSbL=0

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On This Day in Science History - September 11 - Sun Dogs

September 11th marks the passing of French astronomer Joseph-Nicolas Delisle. Among his accomplishments, he was the person who proposed the mechanism behind the sun dog phenomenon.

Sun dogs, or "perhelia" are the bright rainbows that occasionally occur on either side of the sun. They are formed when ice crystals form in the upper atmosphere and reflect the sunlight. If the sun is high enough, a halo or ring can form around the sun. Moon dogs are the same phenomenon at night with the moon.

I am not sure of the origin of the term "sun dog". I have seen references in Greek and Chinese mythology, but have not found any definitive origin. Pass along any stories you have heard about it and find out what else occurred on this day in science history.

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On This Day in Science History - September 10 - Waldo Semon

September 10th is Waldo Semon's birthday. Semon was an American chemical engineer who discovered the process to make vinyl from polyvinyl chloride or PVC. He was working for the BF Goodrich chemical and rubber company to find an adhesive to bond rubber to metal and working with the polymer polyvinyl chloride. PVC in its raw form is a rigid and brittle material with little to no functional use. Semon did not find the adhesive he was searching for, but he did find out a combination of solvents and boiling would turn PVC into a flexible, elastic plastic. Plasticized PVC would become one of the most important and mass produced plastics in use today. It is used in many different construction applications like wiring insulation and plumbing. It is estimated that in the US alone, PVC tubing accounts for up to 75% of plumbing.

Thanks, Waldo! Find out what else occurred on this day in science history.

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On This Day in Science History - September 9 - First Computer Bug

On September 9, 1947, Grace Hopper discovered the first computer bug. She was working as an operator on the Harvard Mark II computer when the operators were attempting to trace a problem in the hardware. Wedged into Relay #70 on Panel F was a large moth's body and causing a short circuit. Hopper recorded and taped the find in the logbook as "The first actual case of bug being found".

This story is the source of many legends. One legend involves the year the bug was found. Most versions, including the Navy's history, has the event taking place in 1945, others, in 1947. Grace Hopper began work on the Mark II computer in 1945 and stayed at Harvard until 1949. The Smithsonian catalog records the date as 1947.

Another common legend has this story as origin of the term 'bug' to mean an error in the system. Bugs have been an engineering term for many years. Edison was quoted in 1878 using the term bugs to refer to problems arising in the engineering process. This was the first 'computer' bug and is often cited as the origin of the term 'debugging' to fix computer issues.

One last legend concerns the location of the now famous log entry, complete with moth. Most stories has the log page on display at the Smithsonian or the Naval Surface Warfare Center Computer Museum in Dahlgren, Virginia. The log was originally kept at the Naval museum but it is now on display at the Smithsonian National Museum of American History.

This story is a fun piece of early computing folklore. Find out what else occurred on this day in science history.

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