Dark Matter Witnessed After Galactic Collision Science Essay
University of Arizona scientist and astronomer Douglas Clowe is as excited as a kid who’s just found where his parents hide the presents at Christmas. Years of planning and research have paid off, he believes, in the imaging of a collision between two galaxies that occurred over 100 million years in the past. The image shows something-or rather, a nothing-that scientists have debated for 70 years.
Science News Online is reporting that Clowe was able to capture imagery of dark matter, a substance that scientists say holds 90 percent of the universe together. The converse theory is that the universe is held together by a mutated version of the theory of gravity. The problem with the dark matter proposal is that it’s generally invisible, thus preventing scientists from proving its existence and validating their theory.
However, Clowe was able to use multiple telescopes and observatories to capture a violent merging of two galaxies that he says resulted in the appearance of dark matter that was unfettered by the explosive reaction.
“Dark matter particles don’t experience the same type of drag that slows down gas clouds,” Clowe told Science News.
Gravity works like duct tape for the universe, he says, keeping regular matter and dark matter merged into an existence so close that like Paris Hilton and her miniature dog, science can’t tell where one begins and the other ends. In a galactic collision like the one Clowe witnessed, gases expand and encounter resistance, effectively slowing the movement of both galaxies. Dark matter, however, is unimpeded by the release of force and passes right through. By his estimation, if dark matter didn’t exist, most of the mass from the collision would have accumulated in one spot, but the intrepid scientists witnessed “clumps” of matter scattered throughout the area. Read the rest of this entry »
The Three Domains of Life
The three-domain system, which classifies life on the planet into three different domains – Archaea, Bacteria and Eukaryote, was put forth by American microbiologist and physicist Carl Woese in 1990. Basically, it is a biological classification of the three domains of life based on the differences in their 16S rRNA genes. Other popular biological classification systems include the two-empire system – also referred to as the super-domain system, and the six-kingdom system. Before we delve into the details of three-domain system, let’s try and understand what this concept is all about, and how it came into existence.
What are the Three Domains of Life?
Before the concept of three domains of cellular life came into existence, life on planet was grouped into two categories – Prokaryotae or Monera (which comprised bacteria) and Eukaryotae (which comprised animals, plants, fungi and protists). In his biological classification, Carl Woese divided Prokaryotae into two groups – Archaea and Bacteria, and thus came into existence the ‘three-domain system’ or the concept of ‘three domains of life’. The division of Prokaryotae into Archaea and Bacteria can be attributed to the fact that neither of the two are ancestors of each other, and even though they share a few common characteristic traits, they have some peculiar traits of their own as well.
Characteristics of the Three Domains of Life
Alongside the three-domain system, there exists a six kingdom system of life, i.e. Archaebacteria (comprising ancient bacteria), Eubacteria (comprising true bacteria), Protista (comprising one-celled organisms), Fungi, Plantae, and Animalia. While Archaebacteria and Eubacteria constitute the Archaea and Bacteria domains respectively, Protista, Fungi, Plantae and Animalia together form the Eukaryote domain of life. Discussed below are the characteristic traits of each of these three domains of life. Read the rest of this entry »
Different Careers in Archeology
Posted by este in Archaeology on August 12, 2011
Study of ancient and modern human culture is known as archeology and a person who conducts research and excavation is known as an archeologist. An archeologist studies the lives of the people of the ancient world from the various scriptures, sculptures and the items that he excavates at a historical site. Apart from excavations, an archeologist also makes research investigations and tries to study the habits, farming and hunting practices of a civilization that had existed thousands of years back.
Careers in Archeology – An Overview
Archeology is a vast field and there are numerous career openings for fresh graduates with a major in anthropology or archeology, who want to pursue their career in archeology. An archeologist focuses his study on the archeological data such as artifacts, features, sites etc and directs his focus on a particular civilization or a particular community.
There are archeologists who focus only on interpreting the data collected from a particular excavation site. They base their interpretation on the basis of materials found on the site such as fragments of bone or clothing, potteries, building material and so on.
Physical Archeology – This is one of the most popular and upcoming branches in archeology. A physical archeologist studies about the human evolution and the habitual changes that are seen in human beings over the period of time. He also studies about the various diets and diseases that were seen in human beings of ancient world and also the modern world. Read the rest of this entry »