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Running Head: COURSEWORK IN LIFE SCIENCE
Coursework in Life Science
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Coursework on Life Science
The Carnot Cycle
The Carnot’s Theorem suggests that no engine operating between two heat reservoirs can
be more proficient than a Carnot engine operating between the same reservoirs. Thus, it gives the
maximum efficiency possible for any engine using the corresponding temperatures. A corollary
to Carnot's theorem provides that all reversible engines operating between the same heat
reservoirs are equally efficient.
In actuality it is not realistic to build a thermodynamically reversible engine, so real heat
engines are less efficient. Nevertheless, it is extremely useful for determining the maximum
efficiency that could ever be expected for a given set of thermal reservoirs.
The Function of a Steam Engine and Refrigerator
The following diagram shows the major components of a piston steam engine. This sort
of engine would be conventional in a steam locomotive.
The engine depicted in the diagram is a double-acting steam engine because the valve
allows high-pressure steam to act alternately on both faces of the piston.

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You can visualize that the slide valve is in charge of letting the high-pressure steam into
either side of the cylinder. The control rod for the valve is typically hooked into a linkage
connected to the cross-head, so that the motion of the cross-head slides the valve as well. To put
it in perspective, this particular linkage connected to the cross-head allows the engineer to put the
train into reverse gear.
You can imagine using this diagram that the exhaust steam simply vents out into the air
after completing the cycle. This fact explains why they have to take on water at the station -- the
water is constantly being lost through the steam exhaust and where the "choo-choo" sound comes
from. When the valve opens the cylinder to free its steam exhaust, the steam escapes under a
great deal of pressure and makes a "chooing" sound as it exits. When the train starts, the piston
moves very slowly, but then as the train starts rolling the piston eventually gains speed.
However for refrigerator, compressor compresses the ammonia gas. The compressed gas
heats up as it is placed under pressure (orange). The coils at the back of the refrigerator let the

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hot ammonia gas disperse its heat. The ammonia gas condenses into a dark blue substance
known as ammonia liquid at high pressure.
The high-pressure ammonia liquid then flows through the
expansion valve. The expansion valve can be seen as a small hole. On one
side of the hole contains the high-pressure ammonia liquid. Due to the
compressor is sucking gas out of that side there exist low-pressure area.
The liquid ammonia almost automatically boils and vaporizes (light blue),
its temperature dropping to -27 F. Hence this makes the inside of the
refrigerator cold. The cold ammonia gas is sucked up by the compressor,
and the cycle recurs.
Ideas of the Ancient Greeks and Poincare
The mathematical problem emerged roughly a century ago from groundbreaking research
of the great French mathematician Henri Poincaré (1854-1912). Before Poincaré, topology was a
little-visited backwater; by the time he had finished, it was a major part of the mathematical
mainstream. Topology is a flexible kind of geometry, a study of what shape things are. But
unlike the rigid geometry of Euclid, with its straight lines and circles, topology allows shapes to
be bent, stretched or otherwise distorted -- though tearing them is frowned upon.
Every popular science book has to tell a story, and O'Shea has framed his story in terms
of the shape of the world. There is an illuminating analogy between Greek geometry and early
attempts to deduce the shape of the Earth, and modern topology and today's investigations into
the shape of the entire universe. This analogy offers so many opportunities to a writer that it is
virtually irresistible, but it has its pitfalls. The main danger is that the framework takes over and

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distorts the history. The casual reader could be forgiven for thinking that the Poincaré Conjecture
emerged from a wish to understand what shape our universe is. The truth is rather different: The
main motivation was the internal structure of mathematics, not anything in the outside world. On
the whole, the book makes this clear.
Poincaré built on what his predecessors had discovered about two-dimensional shapes:
surfaces. The only possible topological surfaces are the sphere, or a sphere with several handles
attached. The great Frenchman sought a similar understanding of three-dimensional shapes, but
when he tried to adapt the methods to three dimensions he hit an annoying obstacle. He could
easily define a three-dimensional analog of the sphere, now known as a 3-sphere. What he could
not do, however, was to characterize that shape topologically.
In two dimensions, a sphere is the only surface in which every closed loop can be
continuously shrunk until it dwindles to a single point. For all other surfaces, the loop can get
caught on a handle, like your finger winding round the handle of a cup. (The cover of the book
has a lovely illustration of an elastic band wrapped around an apple.) For a time, Poincaré
thought that an analogous property characterized the 3-sphere. In fact, he thought this was
obvious, and so made no attempt to prove it.
Later, he realized that an equally plausible characterization along slightly different lines
was actually false, so he tried to prove that any three-dimensional shape, in which every loop
shrinks to a point, must be a 3-sphere. He failed, and realized that the question is extremely
difficult, despite its simple appearance.
Poincaré's question quickly became a conjecture, mathematical jargon for a statement that
everyone believes must be true, but which lacks a proof. The Poincaré Conjecture is vitally
important in mathematics, but not because it tells us what shape the universe is. It is important

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because our entire understanding of three-dimensional shapes depends on it. It is a major
stumbling block in our methods, and until it is overcome, we can't really get started.
The Different Concepts of Dark Energy
Dark Energy is that was invented out of thin air by Einstein because he realized that his
gravitational equations implied that the universe was doomed to a contraction death. To Einstein
this death was a problem because he believed in the Steady State Theory of cosmology (the
eternal model of the universe) so Einstein through in an extra term in his gravitational field
equation to persevere his Steady State interpretation of the Universe and to prevent its inevitable
collapse. Einstein then later retracted his Cosmological Constant term calling it “the biggest
blunder of my life” (because there was no reason to justify its existence save to validate his own
beliefs) and due to observations made by Hubble that the Universe is a dynamic place, but yet
cosmologists have resurrected Einstein's greatest blunder and attempt to write it off as one of his
greatest success. Hence, it is somewhat ironic that the idea of the Cosmological Constant has
been resurrected to justify the belief that Supernova redshift data is an unknown physical
phenomena.
The Cosmological Constant is defined in terms of General Relativity, but since
astrophysicists are framing the Dark Energy debate it is best to start there. The need for Dark
Energy in cosmology comes from the fact that the spectral shifting lines of type IA Supernova
expected from the Hubble Constant do not match their apparent brightness. Type IA Supernova
are believed to always output the same magnitude of energy when they go off (which I by the
way feel is a reasonable assumption) and therefore they can be pictured as standard intergalactic
candles. The key thing to keep in mind with type IA Supernova is that their brightness is
associated with their distance, the further away they are the dimmer they should be and vice-

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versa, all reasonable enough ideas. The problem comes in with the fact that there is also another
measuring scale for intergalactic distances and is measured by something called the Hubble
Constant.
Timeline of Cosmic Changes
We circle around a star that was born approximately 5 billion years ago, in a universe that
is estimated at 13.7 billion years old. Ancient philosophers have thought of the universe as a
static thing – no beginning, no end, and especially unchanging.
However, now we become aware that we are living in a dynamic universe that has only
recently taken on the appearance with which we are familiar. Since the Big Bang, the universe
has undergone radical changes, from the domination of energy to the domination of matter, from
an obscure sea of elementary particles to the transparent vacuum of intergalactic darkness that
greets our eyes when we look skyward at night.

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Reference
Cengel, Y. A., Boles, M. A. (2005). Thermodynamics - an Engineering Approach. McGraw-Hill
Darrigol, O. (2000), Electrodynamics from Ampére to Einstein, Oxford: Clarendon Press
Haynie, D.T. (2001). Biological Thermodynamics. Cambridge University Press
Holton, G. (1973/1988), "Poincaré and Relativity", Thematic Origins of Scientific Thought: Kepler to
Einstein, Harvard University Press
Kelvin, W. T. (1849) "An Account of Carnot's Theory of the Motive Power of Heat - with Numerical
Results Deduced from Regnault's Experiments on Steam." Transactions of the Edinburg Royal
Society, XVI.
Moran, Michael J. and Howard N. Shapiro, 2008. Fundamentals of Engineering Thermodynamics. 6th ed.
Wiley and Sons
Öztas, A.M. and Smith, M.L. (2006). "Elliptical Solutions to the Standard Cosmology Model with
Realistic Values of Matter Density". International Journal of Theoretical Physics
Perrot, P. (1998). A to Z of Thermodynamics. Oxford University Press