Assignment 04 - Science PDF

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ACTIVITY 02 – SCI 10Franz Kylle H. Pocson 201810968 BSA III SEC1. Why is it difficult to distinguish whether a particle is an elementary particle or a composite?This dilemma became a point of principle named "nuclear democracy" which stated that any particle may be considered as a ...

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ACTIVITY 02.2 – SCI 10 Franz Kylle H. Pocson

201810968

BSA III

SEC4

1. Why is it difficult to distinguish whether a particle is an elementary particle or a composite? This dilemma became a point of principle named "nuclear democracy" which stated that any particle may be considered as a bound state of any other particle if conservation laws are respected. The traditional field-theory approach, posited a core set of “fundamental” or “elementary” particles that acted like building blocks, out of which more complex, composite particles could be made was argued that instead picturing each particle as division into “elementary” and “composite” camps, it should be viewed as a kind of bound-state composite of all others; none was inherently any more “fundamental” or special than any other. The statement that particles are elementary if you can't knock anything out of them was not enough since electrons and positrons are created in the collision of electrons with one another or with atomic nuclei; it is indefinite to think that they are knocked out of the electron. On the other hand, pions which are highly interacting particles, are made from collisions of protons with one another. Similarly, protons and antiprotons are also made from collisions of pions with each other. This created a confusion about establishing which was a composite of which.

2. Why are atoms, neutrons, and protons not considered elementary particles? On the other hand, why are electrons considered elementary particles? Electrons are considered elementary particles, they are re more elementary than the other aforementioned particles because their fields appear in theory, which is the Standard Model that applies over a much wider range of energies than the effective field theory that describes nucleons and pions at low energy. Although it is only known to be a type of an electrically charged lepton, it is lightest among other leptons and hence it is stable. Muons and tauons which are other types of leptons can be decayed into electrons and neutrinos, whereas decomposition of electrons into muons or tauons would violate the conservation of energy, implying they cannot be broken down - but this concept is indeterminate nowadays On the contrary, Atoms are not the indivisible constituents of matter, let alone be deemed as elementary particles because they can be further fundamentally subdivided. Proton, neutron and other strongly interacting particles were also declared to be not elementary - in fact they are composites of quarks and gluons, not because of the old definition that quarks and gluons can be knocked out of them but because that is the way they appear in the theory.

3. According to Heisenberg, Pauli, and other like-minded scientists, what are the basic building blocks of matter? Furthermore, according to them, what are the requirements for considering a given particle as an elementary particle?

According to these scientists, the basic ingredients of nature are not particles but fields, such as photons that are bundles of energy of the electromagnetic field and electrons which are also bundles of energy of a different field, the electron field. For a particle to be considered as elementary, in the literal sense, a particle is considered to be elementary only if there is no evidence that it is made up of smaller constituents, they are thought to have no internal structure, meaning that researchers think about them as zero-dimensional points that take up no space.

4. According to the Standard Model, what are the elementary particles? Furthermore, what holds these elementary particles together (to form composite particles or matter)?

The Standard Model, a quantum field theory of elementary particles, describes fields of quarks (which are constituents of nucleons, hyperons, pions, etc.), leptons (electrons, muons and tauons, together with associated types of neutrinos), and the photon and its siblings as the elementary particles. The eight gluons produce strong forces that hold quarks together in the nucleons while W+, W-, and Z0 particles produce weak forces responsible for radioactive processes involving neutrinos.

5. Compare and Contrast the ideas of Democritus with the Standard Model. In particular, did Democritus consider the question about what holds the particles together? The Greek philosophers Leucippus and Democritus were the first proponents of the atomic theory. Democritus thought that a point would be reached at which matter, when continuously cut into smaller parts, could not be cut into still smaller pieces. He named these uncuttable pieces atomos, which means “indivisible” in Greek. The proposed model states the following:

a) Matter is composed of atoms separated by empty space through which the atoms move. b) atoms are solid, homogeneous, indivisible, and unchangeable. c) All apparent changes in matter result from changes in the groupings of atoms. d) There are different kinds of atoms that differ in size and shape. e) The properties of matter reflect the properties of the atoms the matter contains. Though modern ideas conform to the concept that all matter is made up of extremely small building blocks called atoms, the current Standard Model disproves atoms being indivisible and the most fundamental component of matter. But Democritus was on the right path, and far ahead of his time. Today we know that atoms are not the smallest building blocks of matter; rather, there exists a whole world of particles more fundamental than atoms. Democritus' theory wherein different kinds of atoms make up different types of matter coincides with the modern view that atoms of different elements differ in their numbers of protons and electrons giving them different physical and chemical properties. Democritus did not consider what holds the particles together, instead he simply thought that atoms are only separated from one another by emptiness and that it is always in constant motion, unlike the Standard Model which elaborates the weak, strong, electromagnetic forces, and gravity that keeps the particles together.

6. Why do Weinberg and other scientist seriously consider the possibility that the Standard Model is just a tentative explanation for the composition of the universe? The Standard Model is not considered absolute because it has conflicts with other distinct theories, for example, it is still possible that quarks and other particles which the Standard Model considers as elementary particles might actually be composites of more elementary particles. One way to tell is by looking at their sizes as measured by the strengths produced by their spins. Having a non-zero size alone is a sign that it is not elementary. In quantum electrodynamics, electrons are surrounded with a cloud of short-lived photons and electron-positron pairs, which muddles the idea that electrons are elementary particles. Hence, until there is a final theory of force and matter, the answer to the question to which particle/s is/are elementary remains unclear. Despite its great predictive power, however, the Standard Model fails to answer crucial questions, which is why particle physicists know their work is far from done. “It is a very classic example of the scientific method in action, with each answer come more questions; nothing is ever done.”

7. How does the idea expressed in the last paragraph of the essay conform to and/or contradict the idea you held or which you were taught about science? Weinberg's essay contradicts the primary objective of science which is to ask the right question. Like in Democritus case, without much access towards scientific instruments, science enabled him to question the composition of the universe, his theory we’re wrong but that idea stemmed more questions and now we have the Standard Model. Paradoxically, in order to come up with the right question, we must first move close enough to the answer itself. The juxtaposition between instinct and this paradox might confuse an individual. To put it simply, Weinberg tells us that the human mind is limited in devising the exact question to ask without being presented with the right evidences—questions are undoubtedly more important than answers in science. Hence, the proper inquiry starts at knowing enough what one needs to know. This entails another important question in science, "How do we know what we claim to know?"...