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J.J. Thomson & Ernest Rutherford

How does one go about discovering a particle so small that nobody can see it? The British physicist J.J. Thomson won the Nobel prize in 1906 for doing just that—discovering the electron. At Cambridge University, Thomson was the epitome of an absentminded professor, sporting a tweed jacket, round-rimmed spectacles, mustache and dishevelled hair. 

  While exploring the nature of cathode rays, he discovered that he could deflect their path with an electric field. Measuring the amount of deflection under various strength fields, he was able to determine the mass of these particles, which he found to be about 1,800 times lighter than the hydrogen atom. 

  He called these particles “corpuscles,” and (incorrectly) suggested that they make up all of the matter in atoms. Most scientists at the time believed that the atom was the most fundamental unit of matter and indivisible, so to them this was a shocking concept.

The "plum pudding" model of the atom

  Thompson proposed a “plum pudding” model for the atom, in which thousands of tiny, negatively charged corpuscles move about inside a massless cloud of positive charge. This theory was disproved by a former student of Thomson, Ernest Rutherford. By examining how alpha particles scattered after colliding with a thin sheet of gold foil, Rutherford found that the atom must have a small core, or nucleus. Rutherford proposed that the atom might resemble a tiny solar system, with a massive, positively-charged center orbited by electrons.

Rutherford's gold foil experiment

  Luckily the name corpuscles did not stick or else today we would be going to corpuscular stores like Radio Shack, or reading c-mail instead of e-mail. Eventually the word electron gained favor. It comes from the Greek word for amber, which was known for its ability to electrostatically attract small objects when rubbed with fur.

America's Secret Canyon

A Fremont petroglyph

Hidden away in a rugged and remote corner of eastern Utah lies one of the most unique archeological sites in North America—Range Creek Canyon. Native Americans known as the Fremonts lived there for several hundred years up until about 1,300 AD when their way of life came to a sudden and mysterious end. Similar to the Anasazi, the Fremonts were ancestors of today’s Pueblo peoples.

  The site remains largely untouched today thanks to Waldo Wilcox. He is the rancher that owned the land and protected this secret for 50 years until he eventually sold it to the state of Utah in 2001. Currently, the land is under the care of the University of Utah’s Archeology Department.

A stone and adobe granary

  The Fremonts hunted and farmed. They grew corn and stored it in stone and adobe granaries that they built in out-of-the-way cliff sides. Over 38 have been identified so far. These granaries are at many different elevations and often located in extremely precarious spots. It is thought that in lean years they stored their corn in higher, more difficult to reach areas in order to protect their limited food supply. 

A Fremont petroglyph

  They were also prolific artists, creating many carvings into the cliff walls (know as petroglyphs) and paintings in caves and on rocks (known as pictograms). Their cave dwellings were well crafted and a rich source of artifacts: pottery, stone tools, arrowheads and other items. This unique find will no doubt be carefully studied for years to come and promises to reveal many details of their lives.

1) True of false: Ranch Creek Canyon was home to the Fremont people a thousand years ago.

2) The Fremonts relied on the farming of ______________ which they stored in stone and adobe ______________________. 

a) corn, baskets  b) wheat, caves  c) corn, granaries  d) wheat, granaries

3) True or false: Petroglyphs are paintings on rock or cave walls.

4) Range Creek Canyon is being studied by _________________.

a) the state of Utah  b) the Utah University Geology Department  c) Waldo Wilcox  d) the Utah University Archeology Department.

5) The Fremonts are similar to what other ancient tribe?

Apollo 15

Apollo 15's Lunar Rover

NASA called Apollo 15 the most successful manned space flight ever achieved. It was the first moon mission to use the Lunar Rover which allowed the crew to travel greater distances from the Lunar Module than ever before, even though for safety sake they avoided traveling farther than they could safely walk back in case the rover broke down. They also collected 170 lbs. of moon rocks, one of them being the Genesis Rock. When later examined by geologists it was found to be 4.5 billion years old—meaning it was formed shortly after the creation of the solar system.

Genesis Rock

   One of the experiments carried out during Apollo 15’s moon landing—called the hammer and feather drop—was done as a bit of theater to test the original Galileo theory that objects of different mass will fall at the same rate in a vacuum. In it, we see Mission Commander David Scott drop a hammer and feather at the same time form the same height to see if they both hit the ground at the same time. Since the moon has no atmosphere, it was the perfect place to carry out the experiment.





   Hard to believe, but a significant portion of the population still does not believe that the Apollo landings really took place—that they were staged by NASA. One poll of 18 to 25 year old American revealed that 25 percent of them were not sure that the landings actually happened.
   As we have discussed before, one exception is all it takes to disprove a theory and I should think the hammer and feather drop would be enough to dispel this myth. But then again, some people still think Elvis is alive.

Plutonium Pacemakers

A Medtronic plutonium pacemaker from 1974.

How ironic that the heaviest naturally-occurring element, plutonium, was named after the dwarf planet Pluto.
   Plutonium was discovered in 1940 by Glenn Seaborg and his team at Berkeley University. His research became part of the top-secret Manhattan Project, so its discovery would not be made public until after the atomic bomb called Fat Man was dropped on Nagasaki to end World War II. Seaborg would receive the Nobel Prize in Chemistry in 1951 for the discovery of the transuranium elements, including: plutonium, americium, curium, berkelium and californium.
   There are five isotopes of plutonium but only two have commercial uses: P-238 and P-239. P-239 is what is used in nuclear weapons and to fuel nuclear power plants. With a half-life of about 24,000 years, this is some pretty nasty stuff. In 1945 and 1946, during research for the Manhattan Project, two scientists died and many others had their lives cut short in two separate incidents with the same plutonium core that briefly went critical: first because a researcher accidentally dropped a brick on it, and once when a researcher accidentally encased it in a neutron reflector. Due to these accidents, the core would become known infamously as the Demon Core.
   P-238 has a half life of only 88 years and is much less dangerous—its radioactivity is known as alpha decay, where it emits a helium ion instead of gamma or X-rays. This type of radiation is much easier to shield and since a kilogram of P-238 can generate over 500 watts of power for decades, it’s perfect as an onboard power plant for space probes: Viking, Galileo and Cassini to name a few. 
   For a while in the 1970s, P-238 was used to power pacemakers for patients who did not want to risk repeated surgeries every time their battery wore out, and although pacemakers now use lithium-iodide batteries, there are still 50-100 people still living with functioning P-238 pacemakers.

Relativity's First Test

In General Relativity, Einstein describes gravity as
a deformation of space-time around a massive object.

Einstein was the master of the thought experiment, but when it came to real experimentation, not so much. He preferred to make predictions and let the rest of the scientific community scramble to prove or disprove it. Most of the time he was right. But even Einstein was able to admit that “No amount of experimentation can ever prove me right; a single experiment can prove me wrong.” This is an essential characteristic of a scientific theory or hypothesis and is known as falsifiability. Falsifieability is a good thing because it means that a hypothesis is testable and thus conforms to the standards of the scientific method.
   One such case where Einstein’s ideas were put to the test was his General Theory of Relativity, which predicted that in the presence of a gravitational body such as the sun, spacetime would be warped and that light would follow a curved path as a result. Einstein said that light travels along the curve of space-time taking the shortest path between two points, so therefore light is deflected toward a massive object. The stronger the gravitational pull, the more the light path is bent. This idea was received with much scepticism at the time and was in contradiction with Newton’s theories, so scientists were eager to test it.

One of Eddington's photographs of the total solar eclipse of

May 29, 1919, confirming Einstein's theory that light "bends".

  For the British astrophysicist Sir Arthur Eddington, that opportunity came during a total solar eclipse on May 29, 1919. Eddington set out to measure the positions of stars near the sun before and after this eclipse to see if starlight was actually being deflected. Eddington had measured the true position of the stars months before and was able to calculate, according to Einstein’s theory, that there should be an ever-so-slight bending of starlight—now known as gravitational lensing. 

  Eddington’s experiment ended up confirming Einstein’s theory, and by November the London Times ran the headline “Revolution in Science: New Theory of the Universe: Newton’s Ideas Overthrown”.

  Einstein was an international celebrity overnight. When asked what he would have done had the eclipse experiment not agreed with relativity, Einstein replied “Then I would feel sorry for the good Lord. The theory is correct!”.

Exceptions to the rule

One of the founding principles of science is that the exception tests the rule. So if there is an exception to any rule, and if it can be proven by observation, that rule must be wrong. 

  For example, Aristotle believed that heavier objects fell faster than light object, and this was the conventional wisdom for many centuries. Then Galileo decided to test it in his famous Leaning Tower of Pisa experiments. It’s not known if he actually dropped cannonballs of different weights from the tower, but he did discover that regardless of the weight of the objects, they fell at the same rate. 

  So, based on the experimental evidence, Aristotle was wrong—regardless of how great a philosopher he was.

  Another example: Isaac Newton was convinced that space was filled with a “luminiferous ether” in which light traveled through. This was disproved by Michelson and Morley in 1887. They were trying to measure an ether wind by comparing the speed of light in perpendicular directions. The theory was that the earth’s movement through space creates an ether wind that would effect the speed of light in the same way that a jet travels faster in a tailwind and slower in a headwind. What they discovered was that light moved at the same speed regardless of direction, and, therefore, Newton had to be wrong. It would not be until 1905 that we would get a new theory explaining light and how it travels by a 26 year old Swiss patent clerk.

1) True or false: Galileo proved that heavier object fell faster than light objects.

2) A luminiferous ether was hypothesized to be __________.

a) a light-emitting organic compound  b) the medium through which light travels  c) the vacuum of space  d) an optical illusion

3) True of false: Michelson and Morley devised an experiment to measure the speed of light.

4) Which of the following is not true:

a) light travels fastest when moving through a vacuum  b) light displays wave-like properties  c) light is composed of particles d) light moves at the same speed everywhere.

5) A new theory of light was developed in 1905 by ________.

Pluto—It’s a Dog’s World

A comparison of sizes of Pluto and Earth.

How did Pluto lose its planetary status? Discovered by Clyde Tombaugh in 1930 while working for the Lowell Observatory in Arizona, Pluto captured the imagination of the country. Pluto was named by Venetia Burney, an eleven year old girl from Oxford, England. She thought naming the new planet after the Roman god of the underworld was appropriate, considering the new world would be so cold and dark. The Lowell Observatory agreed unanimously. Pluto-mania followed: Disney would name its new side-kick for Mickey Mouse after Pluto. In 1941, Glenn Seaborg named the newly-formed element Plutonium after Pluto as well.
   Pluto’s status as a planet was questioned by astronomers over the years due to its small size, but the final blow was administered by Caltech’s Mike Brown. In 2005, Brown discovered a body in the Kuiper Belt—a region on the outskirts of our solar system littered with icy objects—that was larger than Pluto. Brown named the body Eris and initially considered it to be the 10th planet. But because it was so far from the sun—roughly three times farther than Pluto—members of the International Astronomical Union (IAU) began to worry. What if more planets were out there waiting to be discovered? Where would it end? This prompted them to do something that hadn’t been done since the time of the ancient Greeks—to actually define what it means to be a planet. 
   The pivotal criterion in the IAU definition was that a planet must clear the neighborhood around its orbit of matter, which Pluto does not do. So, after 76 years, Pluto was given the boot along with Eris and any other yet-undiscovered body. They were reclassified as “dwarf planets” instead. At least now the school-kids mnemonic for remembering the order of the planets, “Martha Visits Every Monday and Just Stays Until Noon, Period.” can lose the Period.


Pluto Trivia

• Pluto is smaller than our Moon.
• Pluto’s moon, Charon, is more than half the size of Pluto.
• Because Pluto is so far away, the Sun would look like a bright star from Pluto’s surface.
• Pluto’s has an irregular orbit, and starting in the year 2227, Pluto will be closer to the Sun than Neptune.