The Dinosaur Extinction by Joe Leddy

65 million years ago the most famous mass extinction occurred.  It was at this time that all of the dinosaurs died. What most people do not know is that along with the extinction of the dinosaurs 70% of all species on Earth became extinct at that time?  Therefore any theory that explains the demise of the dinosaurs must be comprehensive enough to include the extinction of the other species as well.

There are two serious theories that have gained acceptance within the scientific community to explain the disappearance of the dinosaurs, the meteor theory and the volcanism theory.  Both of these theories point to the same evidence of the extinction, however, they differ on the root cause.

Analysis of the rocks in and around the end of the Cretaceous Period was conducted by a team of scientists from the University of California (Luis and Walter Alvarez) in Gubbio, Italy.  

What the Alvarez’ s discovered was a thin layer of clay that contained a large quantity of the element Iridium in the rock samples.  Iridium is an extremely rare element in the Earth’s crust, typically only about 0.001 parts per million.  In rock analyzed by the Alverez’s the quantity of Iridium was 30X that amount, this level of Iridium is typically only found in meteorites.  After the initial discovery in Italy, scientists discovered Iridium in many samples from the same layer(now know as the K/T boundary, all over the Earth.  The key to the dinosaur’s extinction is in origin of the Iridium.

It is possible that volcanism could explain both the clay layer and the abundance of iridium. This theory begins with the formation of the Earth.  When the Earth was still molten it was possible, and likely probable, that meteors containing Iridium continued to crash into the planet.  As the planet cooled the Iridium contained in the meteors was buried deep within the mantle of the Earth.  

A series of violent volcanic eruptions that would bring molten material from the mantle to the surface would have then thrust the Iridium out into the atmosphere (in addition to the tons and tons of additional particles).  Once in the atmosphere these materials formed a barrier, that blocked sunlight from reaching the Earth, which led to a global cooling period and eventually an Ice Age.  This shift in the global climate is what is ultimately believed to have caused the mass extinction.

The more widely accepted theory states that a large meteor (about the size of Mt. Everest) containing large amounts of Iridium crashed into the Earth about 65mya. An enormous amount of energy was released during the collision, which sent tons of debris into the atmosphere.  Just as in the Volcanism Theory, this led to the serious climate changes that followed.  Why should this theory be more widely accepted?  

Volcanic eruptions are very common within the history of the Earth, and out-gassing (the process by which volcanoes released gas and contributed to the formation of the atmosphere) has been established to operate on a global scale.

Why would the Iridium show up in these quantities in a “single” geological event?  If it is present in the Earth would we see a more uniform concentration of it, or see less of it on a more frequent basis.

The Meteor Theory explains the presence of the Iridium on a one off basis.  It has been calculated that a 10km meteor, which is not that big on a cosmic scale, would contain enough Iridium to account for the levels found.

Until 1990, many geologists had asked the question “Where is the crater?”  In 1990 Alan Hildebrand was reviewing some data from some scientists looking for oil in the Yucatan region of Mexico.  Mr. Hildebrand uncovered a ring like structure near the small town of Chicxulub; this ring is roughly 65Million years old and 180km in diameter.  This diameter is consistent with the impact of a 10km meteor.

So currently the evidence seems to suggest the Meteor Theory has some credence.  

For more facts and theories see the following links and sources:



What killed the dinosaurs?  http://www.ucnp.berkely.edu/diapsids/extinction.html

BBC – No fiery end  
http://news.bbc.co.uk/1/hi/sci/tech/3295539.stm

Historical Geology 4th Edition by Wicander and Monroe

www.Enchantedlearning.com

The Dinosaur Extinction Page by Andrew Buckley

Gagging Galileo

The year is 1633. In a dimly lit room in the middle of Rome a sickly old man, well respected by his peers, stands before the Inquisition. His crime: wanting to teach the ideas of other scientists.

Years before, in 1609, he turned his new “spyglasses” on the night sky and revolutionized the science of astronomy. He observed that the Milky Way was made up of millions and millions of stars, that the moon was not smooth or perfect and that it had mountains, that four smaller bodies revolved around Jupiter, and—possibly the most important observation—that Venus appeared to go through phases, just like the moon.

I’m no Galileo but I know what that must have felt like. Just ask anyone who talked to me while I was writing my thesis and finally began collecting data that proved my point. It didn’t matter who you were: if you asked how it was going, you were going to get an earful about infrared spectroscopic theory or the dangers of arsenic in the environment or the plight of Bangladeshi.

If you were lucky, after about five minutes I noticed the glazed-over look in your eye and let you go; if you were smart, you just cut me off. That’s the way we are, we “science people.” That passion that leads us to constantly question the world around us is only outshone by our want, our need to tell everyone else what we found. But this isn’t true just for us “science people;” this is what makes educators educators.

Back to Galileo. Galileo was not a stupid man. He lived during a time when the Church ruled the western world, a time when saying something that went against church doctrine could mean death. Galileo was, however, in some ways lucky.

Just a few years after Galileo first turned his telescope to the heavens, in 1616, he wrote a letter to the Grand Duchess Christina of Lorraine. In the letter he argued for the nonliteral interpretation of the bible—at least when a literal interpretation contradicts facts about the physical world. Furthermore, Galileo, for the first time in his professional life, claims in the letter the Copernican theory is not just a mathematical model but a physical reality.

Later that year Pope Paul V ordered the Cardinals of the Inquisition to meet and discuss the Copernican theory. On February 24th, using evidence from the theological experts of the time, the Church condemned the teachings of Copernicus and forwarded their decision to Galileo. From this point on, Galileo was forbidden from holding or teaching Copernican views.

Now about that luck: Shortly after the Inquisition made its findings, a long-time friend of Galileo, Mafeo Barberini, was elected Pope Urban VIII, and Galileo was assured that the Church would not make an issue of the Copernican theory.

For the most part scientists are not political people. We relish this idea of academic freedom; the ability to freely debate ideas and theories and most importantly to teach all ideas is what moves science. It is also what moves the modern world. But this wasn’t always the case, and we cannot forget the errors of the past, the ability of one group to control the thoughts and ideas of an entire society is not taking us forward. In fact it is holding us back.

In true debate the people control thought, and the credence of fact controls the ability of that thought to survive. Ideas, theories, concepts—they survive not because law dictates that they must but because of the will of the people to accept them based on fact and/or the general consensus of belief.

Galileo believed the same. This is why when he finally decided to make his ideas public he did so in a way that he felt would not politically harm his friend Pope Urban VIII and yet would convey his Copernican belief.

In 1624 Galileo began writing The Dialogue. The text was simple; it was debate between a believer in the Copernican (sun-centered) model of the universe and a believer in the Ptolemaic (earth-centered) model of the universe. In the end, as you can imagine, the Copernican view seems to win.

Galileo was summoned to the Inquisition.

The year was 1633, in a dimly lit room in the middle of Rome, a sickly Galileo stood  accused of breaching the conditions of the 1616 Inquisition. Galileo, this time, was not able to debate the facts of his theory. The 1616 Inquisition had already declared them false. This time, Galileo was found guilty of teaching his views and was sentenced to life in prison.

Today, as educators, we still squirm at the thought of Galileo’s fate but at the same time we sit tall, empowered by the idea of academic freedom. But should we?

Recently 7,000 scientists, including 48 Nobel laureates, have signed a statement that the current government administration has willfully censored, distorted, or abused scientific data in an effort to forward a specific political agenda. The data, the statement, and the case studies can be found at www.ucsusa.org/rsi .  

We can now imagine how Galileo must have felt when he found that theologians have decided that Copernicus was wrong.

As a scientist and an educator I like to think that the world has changed because of science. Science is about making progress about advancement. Turn on the TV or the radio and I guarantee that you will hear that phrase at least once in reference to some political stand point. The world is definitely different. But how has the world changed? Has the world changed so much so that we have returned to the 17th century? Shall we once again return to the days of the Inquisition, or have we already?