AS404 –Day 1
The Goals of this Class:
· Difference between scientific thought and philosophical thought
· Learn the basic definitions used in the scientific community
· Learn the basic theories of Quantum Mechanics
· Learn the basic models of chemical structure and reactions
· Understand the cycles of sugar, fat and carbohydrate metabolism
· How living organisms breakdown, create, store and retrieve energy
Grading & The Final Exam:
· All the reading is required
· 50% of your grade is the final exam
· 50% of your grade is the homework and I take the median.
· Your final exam will be 60 questions answered in 2 hours or less
· Questions will be taken from class lecture, homework and all the readings
· 30% questions on Physics, 30% of the questions on Organic Chemistry and 30% of the questions on Biochemistry.
· You will be expected to memorize chemical structures, models and cycles
Definitions
A Form – An Outline of Powers and Limits - Mathematics
A System – A decision made before the question arises – A method used to answer a question
A Principle – A basic truth or law or assumption – Natural Laws
What is science? Study of the Natural World
What is religion? A strong belief in a supernatural power or powers
Science is about Cosmic Order: Religion is about Cosmic Purpose
What is physics? The study of matter and energy.
What is chemistry? The science of matter; how is matter put together? The branch of the natural sciences dealing with the composition of substances and their properties and reactions.
What is biology? The study of living organisms. A much more complex science. It is dealing with matter that is alive!
What is mathematics? The study of patterns of structure, change, and space
Physics is the foundation of all the other sciences. An understanding of science begins with an understanding of physics.
Scientists answer questions:
Who?
What? 90% populace & media focus on these
When?
Where?
How? Engineers – Take theory and put it into practice - lubrication & adhesion
Why? Scientists – Theoretical and Experimental arenas
Just a note: most of the lecture notes that I use are drawn from other websites, textbooks, and electronic library resources. Please do not take the following lecture notes as original! I have copied, compiled and collated. Basically, I have borrowed from the work of people MUCH smarter than me to bring this information to you. I have made every effort to put links in place to send you to the original web sites where this information came from.
The Four Known Universal Forces
Strong Nuclear Force
Electromagnetism
Weak Nuclear Force
Gravity
The Strong Nuclear Force
· It is the strongest
· It has the shortest distance of influence
· Its main job is to hold together the subatomic particles of the nucleus: called nucleons.
· like charges repel (+ +, or - -), and unlike charges attract (+ -).
· why would the nuclei of these atoms stay together?
· The strong nuclear force is created between nucleons by the exchange of particles called gluons. This exchange can be likened to constantly hitting a ping-pong ball or a tennis ball back and forth between two people. As long as this gluon exchange can happen, the strong force is able to hold the participating nucleons together.
· The nucleons must be extremely close together in order for this exchange to happen. The distance required is about the diameter of a proton or a neutron
· The dotted line surrounding the nucleon being approached represents any electrostatic repulsion that might be present due to the charges of the nucleons/particles that are involved. A particle must be able to cross this barrier in order for the strong force to "glue" the particles together
· In the case of approaching protons/nuclei, the closer they get, the more they feel the repulsion from the other proton/nucleus (the electromagnetic force). As a result, in order to get two protons/nuclei close enough to begin exchanging gluons, they must be moving extremely fast (which means the temperature must be really high), and/or they must be under immense pressure so that they are forced to get close enough to allow the exchange of gluons to create the strong force.
· Now, back to the nucleus. One thing that helps reduce the repulsion between protons within a nucleus is the presence of any neutrons. Since they have no charge they don't add to the repulsion already present, and they help separate the protons from each other so they don't feel as strong a repulsive force from any other nearby protons. Also, the neutrons are a source of more strong force for the nucleus since they participate in the meson exchange. These factors, coupled with the tight packing of protons in the nucleus so that they can exchange mesons creates enough strong force to overcome their mutual repulsion and force the nucleons to stay bound together.
· The preceding explanation shows the reason why it is easier to bombard a nucleus with neutrons than with protons. Since the neutrons have no charge, as they approach a positively charged nucleus they will not feel any repulsion. They therefore can easily "break" the electrostatic repulsion barrier to being exchanging mesons with the nucleus, thus becoming incorporated into it.
Electromagnetism
One of the four fundamental forces, the electromagnetic force manifests itself through the forces between charges (Coulomb's Law) and the magnetic force, both of which are summarized in the Lorentz force law. Fundamentally, both magnetic and electric forces are manifestations of an exchange force involving the exchange of photons . The quantum approach to the electromagnetic force is called quantum electrodynamics or QED. The electromagnetic force is a force of infinite range which obeys the inverse square law, and is of the same form as the gravity force.
The electromagnetic force holds atoms and molecules together. In fact, the forces of electric attraction and repulsion of electric charges are so dominant over the other three fundamental forces that they can be considered to be negligible as determiners of atomic and molecular structure. Even magnetic effects are usually apparent only at high resolutions, and as small corrections.
Weak Nuclear Force
One of the four fundamental forces, the weak interaction involves the exchange of the intermediate vector bosons, the W and the Z. Since the mass of these particles is on the order of 80 GeV, the uncertainty principle dictates a range of about 10-18 meters which is about 0.1% of the diameter of a proton.
The weak interaction changes one flavor of quark into another. It is crucial to the structure of the universe in that
1. The sun would not burn without it since the weak interaction causes the transmutation p -> n so that deuterium can form and deuterium fusion can take place.
2. It is necessary for the buildup of heavy nuclei.
The role of the weak force in the transmutation of quarks makes it the interaction involved in many decays of nuclear particles which require a change of a quark from one flavor to another. It was in radioactive decay such as beta decay that the existence of the weak interaction was first revealed. The weak interaction is the only process in which a quark can change to another quark, or a lepton to another lepton - the so-called "flavor changes".
The discovery of the W and Z particles in 1983 was hailed as a confirmation of the theories which connect the weak force to the electromagnetic force in electroweak unification.
The weak interaction acts between both quarks and leptons, whereas the strong force does not act between leptons. "Leptons have no color, so they do not participate in the strong interactions; neutrinos have no charge, so they experience no electromagnetic forces; but all of them join in the weak interactions."(Griffiths)
Beta Radioactivity
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| Beta particles are just electrons from the nucleus, the term "beta particle" being an historical term used in the early description of radioactivity. The high energy electrons have greater range of penetration than alpha particles, but still much less than gamma rays. The radiation hazard from betas is greatest if they are ingested. Beta emission is accompanied by the emission of an electron antineutrino which shares the momentum and energy of the decay. |
| The emission of the electron's antiparticle, the positron, is also called beta decay. Beta decay can be seen as the decay of one of the neutrons to a proton via the weak interaction. The use of a weak interaction Feynman diagram can clarify the process. |
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Gravity
Gravity is the weakest of the four fundamental forces, yet it is the dominant force in the universe for shaping the large scale structure of galaxies, stars, etc. The gravitational force between two masses m1 and m2 is given by the relationship:
This is often called the "universal law of gravitation" and G the universal gravitation constant. It is an example of an inverse square law force. The force is always attractive and acts along the line joining the centers of mass of the two masses. The forces on the two masses are equal in size but opposite in direction, obeying Newton's third law. Viewed as an exchange force, the massless exchange particle is called the graviton.
The gravity force has the same form as Coulomb's law for the forces between electric charges, i.e., it is an inverse square law force which depends upon the product of the two interacting sources. This led Einstein to start with the electromagnetic force and gravity as the first attempt to demonstrate the unification of the fundamental forces. It turns out that this was the wrong place to start, and that gravity will be the last of the forces to unify with the other three forces. Electroweak unification (unification of the electromagnetic and weak forces) was demonstrated in 1983, a result which could not be anticipated in the time of Einstein's search. It now appears that the common form of the gravity and electromagnetic forces arises from the fact that each of them involves an exchange particle of zero mass, not because of an inherent symmetry which would make them easy to unify.
Examples of Trajectories
Common misconceptions about guns:
A dropped bullet will hit the ground before one which is fired from a gun.
As shown in the illustration of a horizontal launch, gravity acts the same way on both bullets, giving them the same downward acceleration and making them strike the ground at the same time if the bullet is fired horizontally over level ground.
Bullets fired from high-powered rifles drop only a few inches in hundreds of yards.
Fired at twice the speed of sound, a bullet will drop over 3 inches in 100 yards, and at 300 yards downrange will have dropped about 30 inches. Plug in numbers into the bullet drop calculation to see for yourself. Ammunition manufacturers contribute to this misconception by stating the drop of their projectiles as just the extra drop caused by frictional drag compared to an ideal frictionless projectile.
Drop of a Bullet
If air friction is neglected, then the drop of a bullet fired horizontally can be treated as an ordinary horizontal trajectory. The air friction is significant, so this is an idealization.
Any point source which spreads its influence equally in all directions without a limit to its range will obey the inverse square law. This comes from strictly geometrical considerations. The intensity of the influence at any given radius r is the source strength divided by the area of the sphere. Being strictly geometric in its origin, the inverse square law applies to diverse phenomena. Point sources of gravitational force, electric field, light, sound or radiation obey the inverse square law. It is a subject of continuing debate with a source such as a skunk on top of a flag pole; will it's smell drop off according to the inverse square law?
Inverse Square Law, Gravity
As one of the fields which obey the general inverse square law, the gravity field can be put in the form shown below, showing that the acceleration of gravity, g, is an expression of the intensity of the gravity field.
Inverse Square Law, Electric
As one of the fields which obey the general inverse square law, the electric field of a point charge can be put in the form shown below where point charge Q is the source of the field. The electric force in Coulomb's law follows the inverse square law.
Inverse Square Law, Radiation
As one of the fields which obey the general inverse square law, a point radiation source can be characterized by the relationship below whether you are talking about Roentgens , rads, or rems . All measures of exposure will drop off by inverse square law.
The source is described by a general "source strength" S because there are many ways to characterize a radiation source - by grams of a radioactive isotope, source strength in Curies, etc. For any such description of the source, if you have determined the amount of radiation per unit area reaching 1 meter, then it will be one fourth as much at 2 meters.
Homework Day 1 -Quantum Mechanics
1. Define the differences and similarities of a Confederation, a Democracy, a Republic and how they interact with the populations of people under them.
2. Define Science and Religion. Explain the different methods used by each to obtain knowledge. Are there any similarities?
3. Define Physics, Chemistry, Biology, Biochemistry and Mathematics. How do these disciplines build upon one another?
4. Define Classical Physics and Quantum Mechanics. Explain the challenges that Einstein had with Newton’s work and what he had to do to overcome preexisting paradigms.
5. What was the Copenhagen Interpretation and who was involved? Why was Einstein so upset by this?
6. What are the four known forces in our Universe? Give examples of what they do and how they interact with matter.
7. What is the difference between Average, Mean, Median and Mode?
8. What is a positive charge? A negative charge? Why was Benjamin Franklin’s assignments “unfortunate”?
