Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Shaun Christensen Professor David Schaffer Physics 1010 – Elementary Physics 27 March 2014 Signature Assignment Part 1 – Star Identification Name: Alpha Centauri A Distance: 1.34 pc Look Back Time: 4.36 years Size: 1.227 R☉ Luminosity: 1.519 L☉ Christensen 2 Name: V766 Centauri (HR 5171) Distance: 3.68 kpc Look Back Time: 12,000 years Size: 980 to 1315 R☉ Luminosity: 470,000 to 1,000,000 L☉ Christensen 3 Name: Beta Crucis Distance: 85.85 pc Look Back Time: 280 years Size: 6.6 R☉ Luminosity: 22,700 L☉ Christensen 4 Name: Gamma Crucis Distance: 26.98 pc Look Back Time: 88 years Size: 113 R☉ Luminosity: 1,500 L☉ Part 2 – Equation Analysis E = mc2 01. The letters E and m represent variables, while c represents a constant. 02. The constant c2 is the speed of light (which, in a vacuum, is 299,792,458 m/s) squared, which equals 89,875,517,873,681,764 m2/s2. However, what this really represents is the amount of energy stored per kilogram (j / kg). The kilograms cancel each other out in the equation, resulting in the joules as latent energy. 03. Yes, energy is directly related as mass multiplied by the speed of light squared. Having a greater mass in an object or system also means having a greater the relativistic energy as well. Christensen 5 04. The statement is true, as a tiny amount of mass can be converted into a huge amount of energy. Nuclear fusion occurs in the cores of stars occurs when atoms of various elements are squeezed together under intense pressure and temperature to form atoms of heavier elements. However, the mass of the atoms of heavier elements are slightly less than the sum of the mass of the atoms of the lighter elements. Consequently, the process releases large amounts of energy throughout the electromagnetic spectrum such as heat, light, and gamma rays. d = gt2/2 05. B – Objects fall at the same speed (if no air resistance) and weight doesn’t matter. From the equation itself, there are no variables indicating mass or weight. The distance an object falls is the quotient of the product of the gravitational constant g multiplied by the variable time t squared divided by 2. v = gt 06. D – Objects fall at the same speed (if no air resistance) and weight doesn’t matter. Again, from the equation itself, there are no variables indicating mass or weight. The velocity of a falling object is the gravitational constant g multiplied by the variable time t. 07. For most of recorded history we thought heavier objects fell faster because, sadly, for most Christensen 6 of recorded history we also were ignorant to presence of an atmosphere. We didn’t understand that a gas acts as a fluid just like water. In particular, we didn’t understand that falling objects encountered air resistance. Objects with a greater surface area encounter more resistance, which slows their speed in comparison to objects with less surface area. It wasn’t until we understood that the air we breathe is a gas, which as a fluid, provides resistance against falling objects. 08. Objects fall at the same speed (excluding air resistance) regardless of mass or weight because of inertia as a property of mass itself. Inertia is the resistance to change in motion— objects at rest tend to stay at rest and objects in motion tend to stay in motion barring external forces. A field of gravity such as Earth’s does exert a greater pull on objects with more mass than objects with less mass. However, because the heavier objects have more mass they also have more inertia as well. The greater pull on an object with more mass is countered by the greater inertia of the object itself in a proportional manner. The result is, not considering the influence of air resistance, objects of different masses in a gravity field fall at the same speed. e = 1 – Tcold/Thot 09. It is possible in theory to achieve 100% energy efficiency by lowering the temperature of the surrounding environment. If the surrounding environment is at 0 Kelvin—absolute zero— then the quotient of Tcold divided by Thot is 0, which results in no wasted energy. 10. However, it is not possible in practice to achieve 100% energy efficiency by lowering the temperature of the surrounding environment. It is impossible to reach absolute zero because even the slightest movement by a particle such as an electron will increase the temperature by even the slightest amount above absolute zero. 11. It is possible in theory to achieve 100% energy efficiency by raising the internal operating temperature. If the internal operating temperature is raised to infinity then the quotient of Tcold divided by Thot is 0, which results in no wasted energy. 12. However, it is not possible in practice to achieve 100% energy efficiency by raising the internal operating temperature. It is impossible to raise the operating temperature to infinity because no material could withstand infinitely high temperatures. 13. It is impossible to build a car that burns fuel that is 100% energy efficient. Because it is impossible to lower the surrounding environment to absolute zero or raise the internal operating temperature to infinity, the quotient will always be greater than zero. Therefore, no matter how efficient the engine, there will be some energy wasted. Part 3 – Learning About A Law Of Physics Christensen 7 Newton’s third law of motion: For every action, there is an equal and opposite reaction. This law states that every interaction involves an opposing pair of forces. This means that when you press down on an object, the object also pushes back up against you with the same force. The force pair are vectors containing equal magnitude but in opposite directions. Example 1: Standing on a bathroom scale exerts a force downward upon the scale, which exerts an equal amount of force back up against your feet. This magnitude of the force is measured as how much you weigh. Note: The strength of the gravity field influences your perceived weight. Standing on the same scale in a weaker gravity field would be an easy way to lose weight. Example 2: Running involves sequentially pushing your feet against the floor at an angle. The floor pushes back against your feet with the same amount of force but in opposite directions, which propels you in a lateral motion. Example 3: Flapping your hypothetical wings thrusts air downward, which lifts you upward with the same amount of force. The amount of force exerted downward as thrust produces an equal amount of force upward as lift for rockets, planes, birds, insects, bats and other flying objects. Part 4 – Explanation Of Fermi’s Paradox And Possible Resolution The Drake equation estimates the number of intelligent civilizations that may exist in the galaxy with access to radio communication. N = R* ∙ fp ∙ ne ∙ fe ∙ fi ∙ fc ∙ L R - The average rate of star formation in the galaxy. fp – The fraction of the stars with planets. ne – The average number of planets that could potentially support life per star with planets. fe – The fraction of planets that could evolve any form of life. fi – The fraction of planets with life that could host intelligent civilizations. fc – The fraction of intelligent civilizations that could develop technology that could broadcast Christensen 8 detectable signs of their existence. L – The length of time for which such intelligent civilizations could survive to broadcast signals. Fermi’s paradox is the observation that, despite probabilistic arguments for the existence of intelligent extra-terrestrial civilizations in the galaxy (and the universe at large), no evidence for such intelligent life has ever been found—at least officially anyway. Unfortunately, eyewitness testimony and claims of abduction doesn’t count as scientific evidence. So if there are so many intelligent extra-terrestrial civilizations in the galaxy and/or the universe with at least the technology to communicate via radio transmissions, where are they, and why have we been unable to communicate with any of them? Explanation 1: The universe is simply too large to reasonably expect near-immediate signs of extra-terrestrial civilizations. Humans have only been broadcasting for around a century now. Traveling at the speed of light, our first radio waves are only about 100 light years away from Earth. There is also an inherent delay with waiting for a response because such a message has to travel the same distance, at the same rate, for the same length of time. Therefore, the furthest we can reasonably expect a response from any hypothetical alien civilization would be any location within a sphere that is 50 light years in radius centered on the Earth. Christensen 9 While that sounds like an impressively large sphere by pedestrian standards, it is still incredibly small compared to the size of our galaxy, let alone the universe beyond it. The Milky Way is estimated to be 100,000 light years across which means our first radio broadcasts have only traveled 1/10,000 of the diameter of our own galaxy. It’s naïve to expect alien civilizations to predict the sudden development of our civilization in its current location and time and bombard us with salutations welcoming us to the intergalactic neighborhood. Christensen 10 Explanation 2: Due to the substantial response times associated with remote communication, extra-terrestrial civilizations are not currently broadcasting signals. It’s difficult to fathom just how much of the universe, whether on the micro or on the macro scale, is composed of empty space. Realizing the vast distances and excruciating response times with broadcasting and receiving remote signals, other alien civilizations have probably already given up hope for communicating by radio broadcasts. Even shortly after its conception, humans publicly questioned whether we should even bother funding and operating SETI (the Search for Extra-Terrestrial Intelligence). It’s likely that other alien civilizations also realized the futility of their efforts and abandoned such projects long ago in the past. If such civilizations developed faster-than-light communication, then they would have even fewer reasons to continue broadcasting signals and patiently waiting for a reply. Explanation 3: We may not even recognize extra-terrestrial civilizations and/or communication. Presume other civilizations in the galaxy emerged thousands, millions, or even billions of years before us. Ponder what the inhabitants of those civilizations would look like. Would they be biological, sentient machines, or could they even transcend the need for a physical body at all? If such alien civilizations developed telepathy or instantaneous communication via quantum entanglement would there any signal to intercept and interpret? Sentient alien life forms may be far more exotic than our wildest dreams. Explanation 4: Intelligent extra-terrestrial civilizations may be aware of our existence, but for various reasons are uninterested or unable to establish communication. The reasons for avoiding contact run the gamut from an ideological “prime directive” not to interfere with the development of our civilizations, paranoid fears of alien invasion or infectious diseases, or that other civilizations simply have a non- adventurous spirit. For example, among the billions of people living in the industrialized world, the overwhelming majority of humans simply don’t ever feel the irresistible need to uproot their lives to move to a remote jungle to dwell among primitive cultures. There are tribes scattered among the rainforests around the Earth that have never made any contact without any modern civilization. We know they exist, and yet we’re content to let them continue their lives undisturbed by the outside world. Imagine what myths or legends they have developed for these hypothetical giant metallic birds—our airplanes and helicopters—that occasionally fly over their villages in the remote jungle. Do members of these tribes report fearful encounters or debate amongst each other with skepticism whether we even exist? If so, do they likewise ask similar questions we do, such as if we exist, then where are we, and why have we not made contact with them? Christensen 11 Christensen 12 There are myriad reasons why intelligent civilizations may be abundant throughout the galaxy yet still not be apparently obvious to our incomprehensibly small presence in an incredibly large universe. We are only barely just beginning to broadcast evidence of our meager history across the vast distances of the galaxy. And ultimately, alien civilizations may simply not feel obligated to embark on an immense voyage just to announce their existence to an unknown and potentially hostile civilization that only recently developed space exploration and weapons of mass destruction. Christensen 13 Works Cited "A Family Portrait of the Alpha Centauri System - VLT Interferometer Studies the Nearest Stars." www.eso.org. N.p., 03 Mar. 2003. Web. 27 Mar. 2015. <http://www.eso.org/public/news/eso0307/>. Digital image. Alaska Commons. N.p., n.d. Web. 27 Mar. 2015. <http://i2.wp.com/www.alaskacommons.com/wp-content/uploads/2013/07/litter-boxwas-cleaned-when-i-woke-up-aliens-kitten.jpg>. Digital image. Crossed Crocodiles. N.p., n.d. Web. 27 Mar. 2015. <https://crossedcrocodiles.files.wordpress.com/2010/04/aircraftid.jpeg>. Digital image. Gawker. N.p., n.d. Web. 27 Mar. 2015. <http://i.kinja-img.com/gawker-media/image/upload/s--S_3mR18--/c_fit,fl_progressive,q_80,w_636/18mhms80bvp27jpg.jpg>. Digital image. Geo.tv. N.p., n.d. Web. 27 Mar. 2015. <http://igeo.tv/wp-content/uploads/2014/03/maxresdefault11.jpg>. Digital image. GreenUpGrader. N.p., n.d. Web. 27 Mar. 2015. <http://greenupgrader.com/files/2008/05/image236.jpg>. Digital image. Inca Glossary. N.p., n.d. Web. 27 Mar. 2015. Christensen 14 <http://www.incaglossary.org/S_files/southerncross1.png>. Digital image. Psychohistorian.org. N.p., n.d. Web. 27 Mar. 2015. <http://www.psychohistorian.org/img/astronomy/stars-individual/beta-crucis-a-b-c-dyzoom.jpg>. Digital image. Wikimedia. N.p., n.d. Web. 27 Mar. 2015. <http://upload.wikimedia.org/wikipedia/commons/c/c9/E%3Dmc%C2%B2explication.svg>. "Fermi Paradox." Fermi Paradox. N.p., n.d. Web. 27 Mar. 2015. <http://www.seti.org/seti-institute/project/details/fermi-paradox>. Gibbs/Carlip/Koks, Philip/Steve/Don. "Is The Speed of Light Everywhere the Same?" Is The Speed of Light Everywhere the Same? N.p., 1996. Web. 27 Mar. 2015. <http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/speed_of_light.html >. Grossman/Risinger, Adam/Nick. Digital image. DailyMail.com. N.p., n.d. Web. 27 Mar. 2015. <http://i.dailymail.co.uk/i/pix/2012/02/27/article-0-11EF84AB000005DC183_964x959.jpg>. Hewitt, Paul G. Conceptual Physics. 12th ed. N.p.: Addison-Wesley, 2014. Print. Howell, Elizabeth. "Drake Equation: Estimating the Odds of Finding E.T. | Space.com." Christensen 15 Space.com. N.p., 26 Mar. 2014. Web. 27 Mar. 2015. <http://www.space.com/25219-drake-equation.html>. Kaler, Jim. "Gacrux." Gacrux. N.p., n.d. Web. 27 Mar. 2015. <http://stars.astro.illinois.edu/sow/gacrux.html>. Kaler, Jim. "Mimosa." Mimosa. N.p., 25 May 2001. Web. 27 Mar. 2015. <http://stars.astro.illinois.edu/sow/mimosa.html>. Kaler, Jim. "V766 Centauri." V766 Centauri. N.p., 25 Apr. 2014. Web. 27 Mar. 2015. <http://stars.astro.illinois.edu/sow/v766cen.html>. Morrison, Ian. Digital image. Jodrell Bank Centre for Astrophysics. N.p., n.d. Web. 27 Mar. 2015. <http://www.jb.man.ac.uk/astronomy/nightsky/AList/ACent.jpg>. "'Uncontacted Tribe' Sighted in Amazon." CNN. N.p., 30 May 2008. Web. 27 Mar. 2015. <http://www.cnn.com/2008/WORLD/americas/05/30/brazil.tribes/index.html>.