User:Cmedvid/sandbox

Article Evaluation

Joseph Priestley

Relevance:

• when discussing theories he studied, the theories are linked to their respective pages
• in the contents box, topics about his life are sorted chronologically
• titles of sections come with the span of years in which the events occurred
• subcategories included to direct attention and define select topics inside timeline
• images dated from certain periods are scattered throughout the article

Viewpoints:

• different aspects of joseph prieshley's work and reactions to it are highlighted
• include quotes from people about their views of him

Citations:

• when discussing vague accreditation, cites the sentence

Ratings:

• it is a featured article

Scientific Revolution

Relevance:

• topics appear to be sorted in content box by subcategory and then by subject inside those
• topics not fully explored in the paragraphs and are instead used as examples have their wiki pages linked to the term for deeper explanation
• there are some block quotes used that may be excessive
• images with relevancy to the topics are placed next to them

Viewpoints:

• the theories of different scientists are discussed
• individual advancements are acknowledged
• criticism of the scientific revolution is provided at the bottom

Citations:

• some references are to other wikipedia pages which seems odd
• other sources link to google books

Ratings:

• used to be a WikiProject

Review (Artificial Gravity) from Emily_Rodriguez

This is a really interesting subject, and you write very well on it, as well as linking relevant articles and citing very concisely!

One thing I think your contribution may benefit from is segmentation/listing. The article is very well put, but would be easier to navigate if you, for example, listed each potential health impact, or issue with implementation, as its own subsection and elaborated underneath. The content need not change; it would just make the site easier to quickly browse.

Project 1

Topic

• History of Laser Cooling

https://en.wikipedia.org/wiki/Laser_cooling

In the above-linked article, the only included sections are the introduction, doppler cooling, and uses. Each section is relatively small, and the doppler cooling section actually links to a main article on the in depth science behind doppler cooling. Even on that page, the history is a short paragraph. As such, I could potentially provide a closer look at the development of not just the science, but the technology as well.

History

Early attempts at laser cooling

At the advent of laser cooling techniques, Maxwell’s theory of electromagnetism had already led to the quantification of electromagnetic radiation exerting a force, however it wasn’t until the turn of the twentieth century when studies by Lebedev (1901), Nichols (1901), and Hull (1903) experimentally demonstrated that force. Following that period, in 1933, Frisch exemplified the pressure exerted on atoms by light. Starting in the early 1970s, lasers were then utilized to further explore atom manipulation. The introduction of lasers in atomic manipulation experiments acted as the advent of laser cooling proposals in the mid 1970s. Laser cooling was separately introduced in 1975 by two different research groups: Hänsch and Schawlow, and Wineland and Dehmelt. They both outlined a process of slowing heat-based velocity in atoms by “radiative forces.” In the paper by Hänsch and Schawlow, the effect of radiative pressure on any object that reflects light is described. That concept was then connected to the cooling of atoms in a gas. These early proposals for laser cooling only relied on “scattering force,” the name for the radiative force. In later proposals, laser trapping, a variant of cooling which requires both scattering and a dipole force, would be introduced.

In the late 70s, Ashkin described how radiative forces can be used to both optically trap atoms and simultaneously cool them. He emphasized how this process could allow for long spectroscopic measurements without the atoms escaping the trap and proposed the overlapping of optical traps in order to study interactions between different atoms. Closely following Ashkin’s letter in 1978, two research groups: Wineland, Drullinger and Walls, and Neuhauser, Hohenstatt, Toscheck and Dehmelt furthered refined that work. In specific, Wineland, Drullinger, and Walls were concerned with the improvement of spectroscopy. The group wrote about experimentally demonstrating the cooling of atoms through a process using radiation pressure. They cite a precedence for using radiation pressure in optical traps, yet criticize the ineffectiveness of previous models due to the presence of the Doppler effect. In an effort to lessen the effect, they applied an alternative take on cooling Magnesium ions below the room temperature precedent. Using the electromagnetic trap to contain the Magnesium ions, they bombarded them with a laser barely out of phase from the resonant frequency of the atoms. The research from both groups served to illustrate the mechanical properties of light. Around this time, laser cooling techniques had allowed for temperatures lowered to around 40 Kelvin.

Modern advancements

William Phillips was influenced by the Wineland paper and attempted to mimic it, using neutral atoms instead of ions. In 1982, he published the first paper outlining the cooling of neutral atoms. The process he used is now known as the Zeeman slower and became one of the standard techniques for slowing an atomic beam. Now, temperatures around 240 microKelvin were reached. That threshold was the lowest researchers thought was possible. When temperatures then reached 43 microKelvin in an experiment by Steven Chu, the new low was explained by the addition of more atomic states in combination to laser polarization. Previous conceptions of laser cooling were decided to have been too simplistic. The major breakthroughs in the 70s and 80s in the use of laser light for cooling led to several improvements to preexisting technology and new discoveries with temperatures just above absolute zero. The cooling processes were utilized to make atomic clocks more accurate, improve spectroscopic measurements, and led to the observation of a new state of matter at ultracold temperatures. The new state of matter, the Bose-Einstein Condensate, was observed in 1995 by Eric Cornell, Carl Wieman, and Wolfgang Ketterle.

Project 2

Topic 2

• Improving artificial gravity article:
• Wikipage

In the above linked article, there is a note at the top that the introduction is not comprehensive, and that can be fixed with a few summarizing and clarifying sentences of expansion. Additionally, there is not pros and cons section about the impacts of the implementation of artificial gravity, why it is considered necessary, and why it is not in practice yet. The title of that added section would not be pros and cons, but it would convey a paragraph based version of that concept.

Introduction Redux

Artificial gravity is the creation of an inertial force that mimics the effects of a gravitational force. Not to be confused with the intermittently experienced linear acceleration felt by astronauts from the force created by a rocket engine, artificial gravity is commonly used to refer to a sustained normal force. That normal force can be created through a number of methods such as rotation, linear acceleration, and magnetism. Artificial gravity has been used in simulations to help astronauts train for extreme conditions. Additionally, simulated gravity in manned spaceflight has been proposed as a solution to the adverse health effects caused by prolonged weightlessness. However, there are no current practical outer space applications of artificial gravity for humans due to concerns about the size and cost of a spacecraft necessary to produce a useful centripetal acceleration comparable to the gravitational field strength on Earth (g).

Health benefits during manned spaceflight

Artificial Gravity has been suggested as a solution to the various health risks associated with spaceflight. In 1964, the Soviet space program believed that a human could not survive more than 14 days in space due to a fear that the heart and blood vessels would be unable to adapt to the weightless conditions. This fear was eventually discovered to be unfounded as spaceflights have now lasted over 500 days, however the question of human safety in space did launch an investigation into the physical effects of prolonged exposure to weightlessness. In June 1991, a Spacelab Life Sciences 1 flight performed 18 experiments on two men and two women over a period of nine days. In an environment without gravity, it was concluded that the response of white blood cells and muscle mass decreased. Additionally, within the first 24 hours spent in a weightless environment, blood volume decreased by 10% . Upon return to earth, the effects of prolonged weightlessness continue to have an impact on the human body as fluids pool back to the lower body, the heart rate rises, a drop in blood pressure occurs and there is a reduced ability to exercise.

Artificial Gravity, due to its ability to mimic the behavior of gravity on the human body has been suggested as one of the most encompassing manners of combating the physical effects inherent with weightless environments. Other measures that have been suggested as symptomatic treatments include exercise, diet and penguin suits. However, criticism of those methods lays in the fact that they do not fully eliminate the health problems and require a variety of solutions to address all issues. Artificial gravity, in contrast, would remove the weightlessness inherent with space travel. By implementing artificial gravity, space travelers would never have to experience weightlessness or the associated side effects. Especially in a modern day six-month journey to Mars, exposure to artificial gravity is suggested in either a continuous or intermittent form to prevent extreme debilitation to the astronauts during travel.

Issues with implementation

Some of the reasons that artificial gravity remains unused today in spaceflight trace back to the problems inherent in implementation. One of the realistic methods of creating artificial gravity is a centripetal force pulling a person towards a relative floor. In that model, however, issues arise in the size of the spacecraft. As expressed by John Page and Matthew Francis, the smaller a spacecraft, the more rapid the rotation that is required. As such, to simulate gravity, it would be more ideal to utilize a larger spacecraft that rotates very slowly. The requirements on size in comparison to rotation are due to the different magnitude of forces the body can experience if the rotation is too tight. At the moment, there is not a ship massive enough to meet the rotation requirements, and the costs associated with building, maintaining, and launching such a craft are extensive.

In general, with the limited health effects present in shorter spaceflights, as well as the high cost of research, application of artificial gravity is often stunted and sporadic.