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Stars And The Universe


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Stars And The Universe Essay, Research Paper

Luminosity is the amount of light that is radiated from a star. White light is the composition of all colors. In elements, the energy discharge can be displayed as light. Just by looking at the colors that are discharged, one may precisely identify the element. In understanding the universe, the Doppler effect is one of the most important tools. The Doppler effect is a shift in frequency due to a moving source. Skipping a rock on water would be an example of this effect. The circles would be off center because the rock is a moving source. The wavelength is shorter when the rock is coming toward an individual. Also, the frequency will increase and the wave crests will shorten. When the source is moving away from an individual, the wavelength increases and the frequency decreases. This principle is identical with light.

In a rainbow, the longest wavelength is the red portion and the shortest wavelength is the violet portion. If a body is emitting light and it is approaching someone, we would say the radiation is blue shifted. A red shift, on the other hand, ocurs when the emitting object is receding, or when a spectrum is shifted to longer wavelengths. Hubble measured that the farther the distance of a galaxy is from us, the greater the red shift, which is Hubble’s law. In fact, galaxies possibly could be receding from us as fast as the speed of light. The greater the distance of a galaxy, the greater its velocity. The universe is constantly expanding in all directions. There is a raisin cake model to explicate this, considering the raisins to be the galaxies and the cake being the space between. The raisins are uniformly distributed throughout the cake, just as the galaxies are throughout the universe. If we bake the cake, as it rises the raisins will spread farther apart from one another. The neighboring raisins, closest perhaps to the one in the center, would not move as fast as ones farther away because there is more cake between it and the center raisin to expand. Therefore, all galaxies move away from each other because one is increasing.

Fritz Zwicky mapped the sky and discovered galaxies are formed in clusters. Members of a cluster move under the influence of their own gravitational pull together. The Local Group cluster consists of thirty galaxies and it is the most prominent galaxy. Containing the Milky Way and Andromeda, this is our own cluster, which is 8.5 million light years long, holds thousands of galaxies and is very dense. They all move togethr with their mutual gravities. The Virgo cluster is 52 million light years away from the Local Group. The Local Super cluster contains 100 member cluster, including the Local Group and the Virgo cluster. It is 100 million light years across and 10 million light years thick. There are three types of evolutions of galaxies, which are spiral, irregular, and elliptical. Spiral galaxies are categorized depending on how tightly bound the arms are. Irregular shaped galaxies are thought to have occurred from galactic collision. Elliptical galaxies are circular in shape to very elongated. Nebula are composed of various kinds of gas and dust, and we can tell what they are composed of by their color. A Supernova, which is an explosion of stars, leaves Nebula. Our complex molecules originated from within stars. Galaxies are not classified by shape, but rather by radio emmisions. Two of the most powerful galaxies found by telescope after World War II were M87 or Virgo A (radio name) and NGC-5128 or Centaurus A ( radio name). After time, galaxies stop emitting and their lobes spread out. Our galaxy has an active center, but we can not see it because of the spiral arms. These galaxies are in a category named BL Lac objects. Stuff shoots out of these galaxies because of the bulging galactic center. Violent radio jets are emitted that originate from a tiny central object. Galaxies are thought to form around huge black holes that are pulling matter into it at all times. Every galaxy that the Hubble space telescope has seen has a black hole in the center, so black holes could be how galaxies originate. Old Faithful is a black hole that is in the center of our galaxy, the Milky Way. Every half hour it gives off the equivalent of one trillion ton asteroid at nearly the speed of light, which is six trillion times the energy we use in the United States annually. Stronger galactic sources are classified as Seyford type I and II, and they are the next strongest up to Quasars. Somehow, Quasars form and are massive radio emitters, then they transform to Seyford type I, then to Seyford type II, then to BL Lac objects, and then they quit emitting radio waves. Occulation is using the moon to calculate its position because we know the exact position of the moon. 3C 273 is a QSO, or a Quasi Stellar Object. Black holes, which weigh a thousand billion times our sun, are the center of Quasars, which go up to the edge of the known universe.

Newton’s static universe theory says that the universe is infinite. There is an infinite number of stars in infinite space that are roughly distributed equally. There is no center point because every point can be the center. Also, he said there is no cantral place for the stars to collapse. This theory is wrong. Aristotle and the Greeks thought that mankind and everything around them had and will reamain the same for all time. Then gravity was thought to be repulsive for long and short distances, but it does not effect much and it is still attractive. For this model to work there would have to be no motion in the universe. Stable equilibrium can be illustrated by a pencil on its side, and unequal by a pencil balanced on its tip which physics does allow. Any possible motion would knock the pencil down though, such as air or talking in the room. Einstein’s General Theory of Relativity suggested an expanded universe. He introduced a cosomological constant to the theory to make the universe seem static, or unchanging. This theory introduced a small change; a constant term that created an anti-gravity force that existed in equations. There was no explanation for it and no known source. In other words, he pulled this term out of nowhere. Einstein later called this his greatest mistake after Hubbles discovery that proved the universe is constantly expanding. In 1922, seven years before Hubbles discovery of the red shift, a Russian mathematician, Alexander Friedmann, based the model of the universe on Einstein’s General Theory of Relativity without the cosmological constant. In 1935, Friedmann’s three models of the universe were introduced. The first assumption was which ever way one may look, everything at any point in the universe will appear to be identical. Hubble’s law proved this seven years later. The universe is not totally uniform, but on an average is considered to be uniform. On a large scale (multiple galaxies) this theory works. Friedmann envisioned the universe to be like the surface of a balloon, and galaxies could be treated like spots on the balloon. Spots will move farther away from each other when you blow it up and it increases. No single spot is the center of expansion. The further apart the dots are, the faster they move away from each other. Friedmann’s law predicted exactly what hubble’s law proved. Friedmann’s model of the universe is not infinite. Gravity is so stron inthis model that it pulls the universe in upon itself. The universe is finite and has no boundaries, and at some point in time it will stop expanding and become a singularity. The second model says space is curved outward instead of inward like the first model. It is comparable to a saddle. This makes the universe an open model, or infinite. The third model says space becomes flat. The universe expands, gravity pulls on it, and then it reaches an acetote and levels out. It still wants to expand and gravity makes it want to contract. This makes space infinite and flat. We look at how fast galaxies move away fro each other, because Hubble’s law is based on the brightness of distant stars. From the knowledge that we have and through measurements of matter, model two would be the most precise one.

90% of all matter in the universe is dark matter that we can not detect. If this theory is true, everything we know of is compressed down to a point and then expands rapidly in all directions. The Big Bang theory, which is the sudden appearance and expansion of the universe from nothingness, is a singularity that some people believe. The distance to neighboring galaxies is zero at the Big Bang. This was conceived in the mid 1930’s to agree with Friedmann’s models, and gained acceptance in the 1960’s. The theory of Relativity fails to explain this, and all theories for that matter break down at a singularity. Whatever happened before the Big Bang have no consequence to the aftermath. Our concept of time starts from the Big Bang. The Catholic church liked this concept in that it leaves room for somethin to start it, which coincides with creation. Stephen Hawkin and Roger Penrose confirmed the Big Bang mathemathically that the begining of the universe began with singularity. physics break down with a singularity and therefore science loses its predictability.

Because of the expansion of the universe we may have five forces, but we only know of four. If the rate of expansion is increasing, Hubble’s constant might not be constant. We can find the rate of expansion when we calculate the age of the universe by shrinking the distance of the galaxies back to zero. Through velocity and distance we can calculate time. We think the universe is 13 or 14 billion years old. An alternate to the Big Bang was proposed in 1948 by Hermand Bondi, Thomas Gold, and Fred Byle. It was called the steady state theory and it argued that the universe never had a beginning and will never end. They said it will always look about the same, and that galaxies appear out of nothing. When Quasars were discovered, this theory was severely crippled. There were more Quasars in 1960 than now which proved change. The discovery of cosmic background radiation and Hawking and Penrose killed the idea of the Steadt State theory.

Arno Penzias and Robet Wilson tested a very sensitive microwave detector while looking for sources of microwave radiation which would hinder microwave signals. They picked up more static than anything and did not know where it came from. They eventually found out that it came from all around. The static was the same day and night and throughout the year in all directions. The source of it came from somewhere outside of the galaxy. Radiation is a constant that has moved across all of the observable universe, so the universe must have been the same or roughly the same at one time. This went on to validate Friedmann’s models of the universe. Bob Dicke and Jim Peebles worked on the idea that the universe was very hot and dense at the beginning so that it glowed white hot. They said they we should still be able to see this glow from the radiation because it would just be reaching us now. They predicted that the temperature was high during the Big Bang and radiation has Red shifted. Radiation was tested for a planck curve and the results were three Kelvins. All elements will be frozen solid with the exception of helium. The main confirmation of the Big Bang theory is the fact that radiation is isotropic, or uniform in all directions. The universe began homogeneously and symmetrically. Astronomers analyze all the different kinds of radiation to understand why and how we exist. Only microwaves and radio waves make it through the Earth’s atmosphere so that is why we launch telescopes. We also do not have to worry about the weather. We can also put them up in a helium balloon into the upper levels of the Earth’s atmosphere. If the earth’s atmosphere and ozone were not there, we would be cooked, the ocean would boil off, polar ice caps would melt, and life would end on Earth. Dicke and peebles modified the Big Bang theory to the Hot Big Bang theory by their observations. Light can be a wave or a particle depending on how energy is structured, and this is where cosmic radiation comes into the Hot Big Bang model. If it is a particle it is a photon, or a light package. Hydrogen ions, which are proton and neutron stuck togethr, could absorb photons and spit it back out at a different frequency, so there is a continuous radiation spectrum across the sky. The universe was opaque with radiation for the first million years or so after the Big Bang. Then the universe expanded enough so that it cooled down to about 3000 Kelvins, which occurred millions of years after the Big Bang. The temperature and density was low enough that hydrogen ions and electrons combined to form a hydrogen atom, and it started to be matter and not just radiation. In this instant the universe is expanding and penzias and Wilson proved there is background radiation. Everything else is theory.

In 1905, Einstein suggested that atoms might be proven to exist if we observed dust particles moving in a random manner in liquid. if dust particles are uniform the atoms would not have existed. In 1911, Ernest Rutherford showed that atoms do exist. An atom is a positively charged nucleus and negatively charged electrons that orbit around the nucleus. He analyzed how material reacted with electro magnetic fields to prove it. James Chadwick discovered the neutron, which is a neutrally charged particle. They do not react to the electro magnetic field and they are the building blocks of matter. During the late 1940’s many new particles were discovered because technology had improved. We saw more trails occur when particles collided which reveals new particles. Over 300 particles have been found, many existing for only a brief period of time, such a fraction of a second. In 1063, Murray, Gill, and Mann proposed that most of the unstable particles, along with the protons and neutrons are composed of a more fundamental particle called the quark. At first they thoought there were three quarks, but found out later there were actually six. They make up most of the 300 particles that we know of with the exception of a few. The building blocks of matter are quarks and Leptons, and there are six of each. Hadrons are Baryons and Mesons, and they are composed of quarks. A baryon is matter composed of three quarks, and an example of this would be a proton and a neutron. Mesons are formed from a quark plus antiquark. leptons are the leftovers which are electrrons, muons, tau, and three neutrinos. The electron is the most stable of the six.

Visual particles take the form of waves. We can not detect them, but we can see their effects. When light acts as a wave it is virtual particle called a photon. There are four forces of nature that make virtual particles exist are gravity, electromagnetism, strong nuclear, and weak nuclear. Gravity is thge weakest of the four forces. It effects all known particles, and is always attractive, so we can see it carried by gravitons which range infinite. It is a small scale inside of a nucleus. A photon is the virtual particle for the force of electromagnetism. This is the next to the weakest force, and it interacts with everything that has a charge. It is massless, or we have not detected it yet, and because it is massless it has infinite range. Electromagnetism also allows particles to be bonded. When two electrons pass close to each other, they give off light. The strong nuclear force is the strongest of the forces. This binds quarks together and holds protons and neutrons together withinthe nucleus. It is really strong within the nucleus, but very weak outside. It is virtual particle is a gluon. The weak nuclear force is the next to the strongest. Its particle is called massive vector bosons, and they are W+, W-, and Zo. This is responsible for radioactivity decay range at 10 to the negative 15 meters.

All matter is attracted to everything else, and we see the effects of gravity because we stay on this planet. The universe is always accelerating and maybe it is repulsive gravity or maybe it is the fifth force actiing repulsive. We do not know which it is because we have not built a tool that will answer this question. Abdus Salam and Stephen Weinberg united the electro force and the weak nuclear force into the electro weak force, so now there are only three forces. So far there has been no clear theory to unify gravity with the other three forces, but it is thought to be accomplished at high energy levels. Only the heat of the Big Bang would be enough to unite the four forces. The inflationary model was proposed by Alan Gouth in 1981, which makes the universe and intelligent life in it a more probable event. This says that the universe went under a phase transition, or a breaking up of symmetry. For example, the freezing of water from a liquid state (water) to a solid state (ice). The inflationary model is widely accepted today, but people are starting to doubt the reality of cold dark matter. Perhaps there are Machos (massive, compact, halo, objects), or maybe there are tons of black holes. Saggitarius is running into the Milky Way and it is holding together rather well. Perhaps there is some other kind of matter that we do not know about. The inflationary model starts like the Hot Big Bang model. Supposedly, less than a second after it blows, it drops from infinite to 10 to the 28 Kelvin. During this period there is a symmetry breaking and gravity seperates the other forces. The strong nuclear force seperates from the electro weak force. Then the universe is supercooled. The size of the universe increases 10 to the 100 because it drops below the normal temperature, and more energy than usual is created which in turn causes pressure on the inside of a tiny new universe. The pressure acts as the pressure inside of a balloon. During the phase change, many atomic particles occur which are many of the building blocks of matter today. The Heat Death Fluctuation model says that the Big Bang was the highest state of order, and that everything else is entropy, which turns order into chaos. The Inflationary model solved some questions of the Hot Big Bang model. Why was the universe so hot in the beginning? Accelerated expansion allowed for light to travel across the entire universe. Why was the temperature at so near a critical rate of expansion? ( Why was space almost flat?) The inflationary model says because it has to be if it is going to be supercooled. We would almost have to have flat space. The inflationary period did not end all at once, therefore the local irregularities could have formed. Random fluctuations must be present in order to have life. This does not solve all of the problems though, such as, is the universe expanding at an increasing rate?, we can not see matter, we can not see past the Big Bang, so what happened before it occurred? Astronomers have had many theories about what happened before the Big Bang. maybe the universe was created out of the collapse of a previous universe. Maybe black holes suck everything in, and then when there is nothing left perhaps it just pushes everything out. Maybe the Heat Death fluctuation model is correct and we live in a universe out there or maybe our universe supercooled and expanded. We do not know a lot. We do not even know if a quark is the smallest particle. Maybe the uncertainty principle keeps the universe apart. Black holes stretch the fabric of time to an infinite extent, tearing a hole in space time. What happens at the tear? Some say at the tend of a black hole some of the matter decreases because it loses energy through its jets and tears, creating litle bubbles. The little bubbles could be the universes. With science, we will never be able to answer why we are here.

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