Black Holes Essays (3493 words) - Black Holes, Star Types

Black Holes Black holes are objects so dense that not even light can escape their gravity, and since nothing can travel faster than light, nothing can escape from inside a black hole . Loosely speaking, a black hole is a region of space that has so much mass concentrated in it that there is no way for a nearby object to escape its gravitational pull. Since our best theory of gravity at the moment is Einstein's general theory of relativity, we have to delve into some results of this theory to understand black holes in detail, by thinking about gravity under fairly simple circumstances. Suppose that you are standing on the surface of a planet. You throw a rock straight up into the air. Assuming you don't throw it too hard, it will rise for a while, but eventually the acceleration due to the planet's gravity will make it start to fall down again. If you threw the rock hard enough, though, you could make it escape the planet's gravity entirely. It would keep on rising forever. The speed with which you need to throw the rock in order that it just barely escapes the planet's gravity is called the "escape velocity." As you would expect, the escape velocity depends on the mass of the planet: if the planet is extremely massive, then its gravity is very strong, and the escape velocity is high. A lighter planet would have a smaller escape velocity. The escape velocity also depends on how far you are from the planet's center: the closer you are, the higher the escape velocity. The Earth's escape velocity is 11.2 kilometers per second (about 25,000 M.P.H.), while the Moon's is only 2.4 kilometers per second (about 5300 M.P.H.).We cannot see it, but radiation is emitted by any matter that gets swallowed by black hole in the form of X-rays. Matter usually orbits a black hole before being swallowed. The matter spins very fast and with other matter forms an accretion disk of rapidly spinning matter. This accretion disk heats up through friction to such high temperatures that it emits X-rays. And also there is some X-ray sources which have all the properties described above. Unfortunately it is impossible to distinguish between a black hole and a neutron star unless we can prove that the mass of the unseen component is too great for a neutron star. Strong evidence was found by Royal Greenwich Observatory astronomers that one of these sources called Cyg X-1 (which means the first X-ray source discovered in the constellation of Cygnus) does indeed contain a black hole. It is possible there for a star to be swallowed by the black hole. The pull of gravity on such a star will be so strong as to break it up into its component atoms, and throw them out at high speed in all directions. Astronomers have found a half-dozen or so binary star systems (two stars orbiting each other) where one of the stars is invisible, yet must be there since it pulls with enough gravitational force on the other visible star to make that star orbit around their common center of gravity and the mass of the invisible star is considerably greater than 3 to 5 solar masses. Therefore these invisible stars are thought to be good candidate black holes. There is also evidence that super-massive black holes (about 1 billion solar masses) exist at the centers of many galaxies and quasars. In this latter case other explanations of the output of energy by quasars are not as good as the explanation using a super-massive black hole. A black hole is formed when a star of more than 5 solar masses runs out of energy fuel, and the outer layers of gas is thrown out in a supernova explosion. The core of the star collapses to a super dense neutron star or a Black Hole where even the atomic nuclei are squeezed together. The energy density goes to infinity. For a Black Hole, the radius becomes smaller than the Schwarzschild radius, which defines the horizon of the Black Hole: The death explosion of a massive star, resulting in a sharp increase in brightness followed by a gradual fading. At peak light output, supernova explosions can outshine a galaxy. The outer layers of the exploding star are blasted out in a radioactive cloud. This expanding cloud, visible long after the initial explosion fades from view, forms a supernova remnant. So, a black hole is an object, which is so compact that the

Dreams Why We Dream, Meaning of Dreams, and Psychology of Dreams Professor Ramos Blog

Dreams Why We Dream, Meaning of Dreams, and Psychology of Dreams Have you ever thought about dreaming and how confusing it all is? There are so many questions people have involving dreams. Like, what do they mean? Or what’s happening in our brains when we do dream? For many years, I’ve thought the same thing and have been in awe about how much there is to know about dreams and how complex they really are. Several years of research and studies have been done and are even currently in process to understand as much as possible about dreams. In this report, we will be finding out all of the unknown questions about dreams and get to understand them a little better. I will cover why we dream, what dreams mean, and the brain psychology of dreaming. This is important in order to better comprehend what dreaming is all about and will benefit anyone wanting to learn more about dreams or hoping to find information on recurring dreams. The big question is, why do we dream? Many sources will say there is no factual evidence for why we dream and in result like to think â€Å"dreams have no purpose or meaning and are nonsensical activities of the sleeping brain,† (Dreams: Why We Dream, Lucid Dreaming, Nightmares, Common Dreams, and More). Although, some studies have proved that having dreams is essential to human health and has an impact on the human body. In the article, â€Å"Dreams: Why We Dream, Lucid Dreaming, Nightmares, Common Dreams, and More†, a study was introduced where, â€Å"researchers woke subjects just as they were drifting off into REM sleep. They found that those who were not allowed to dream experienced, increased tension, anxiety, depression, difficulty concentrating, lack of coordination, weight gain, tendency to hallucinate†. Many experts also say that â€Å"dreams exist to help solve problems in our lives, incorporate memories, [and help] process emotions† (Dreams: Wh y We Dream, Lucid Dreaming, Nightmares, Common Dreams, and More). So, some believe that if you go to sleep with something negative on your mind, you may wake up with a solution to the problem; or at least feel better about the situation. Many scholars from different time periods have had different theories of why we dream. Including, â€Å"Freud’s theory centred around the notion of repressed longing the idea that dreaming allows us to sort through unresolved, repressed wishes,† (Linden). But, based on the â€Å"activation-synthesis hypothesis† dreams â€Å"are merely electrical brain impulses that pull random thoughts and imagery from our memories,† (Linden). So at this point in time, with the current research we have available, the actual reason of why we dream is technically unknown. But, studies have proved they do have an impact on us in one way or another. Including, allowing us to process memories and emotions subconsciously. Another one of the most common questions about dreams is what do they mean? You can ask any psychologist and they might all tell you different answers. Because just like the last question, there isn’t scientific evidence to back up their theories. But, there are still countless articles and books on the topic that explain what experts and scholars like to think is the truth. There are all different types of dreams, including: nightmares and normal dreams. In normal dreams, what you’re dreaming about seems like reality and stays that way until you wake up and realize you were only sleeping. Most of the time, these dreams are generally positive and involve activities that make no sense and usually jump from one random thing to the next. When dreams turn into nightmares, we are still unaware that we’re dreaming. But, the visuals and emotions are negative and frightening and feel extremely real. Some dreams might be â€Å"strange stories that dont relate to normal l ife† (Dreams: Why We Dream, Lucid Dreaming, Nightmares, Common Dreams, and More). Others might feel too familiar and remind of something that has happened in the past or feels like it could actually mean something. Some experts will say that specific dreams have one meaning, but others will say that the reasoning behind your dream is specific to you and can’t be figured out that easy. Reports will show that humans tend to have similar dreams to each other and often have recurring dreams as well. As told by Michelle Carr, â€Å"Recurrent dreams occur in between 60 and 75 percent of adults, and more often in women than men† and that â€Å"the common themes include: being attacked or chased, falling, being stuck, being late, missing or failing an exam, and even losing control of a car† (Carr). These type of dreams are said to reveal â€Å"the presence of unresolved conflicts or stressors in an individual’s life† (Carr). Carr explains an example of a person having a recurring dreams of missing an exam final; which was developed when they started college. But, even after completing school and moving onto their career, they’re still experiencing the dream. For instance, they have the same dream the night before an important meeting at work and this shows, â€Å"the same feelings of stress, and the desire to perform well, can trigger t he relevant recurrent dream† (Carr). This proves not only that overwhelming emotions are present in the dreamer, but that there are unresolved problems in the dreamer’s life. â€Å"The Tidal Wave dream is an examplethat represents overwhelming emotions such as helplessness and fear. The Tidal Wave dream is a common dream to experience following trauma or abuse, and often becomes a recurrent theme that reflects a person’s struggling with integrating and accepting the trauma† (Carr). If recurring dreams start to not happen as often or stop all together, this means that the trauma or emotions causing the dream have been resolved. Lastly, we must ask what is happening when we dream? Research and studies have proven what is actually going on in your brain when we are dreaming. There are generally five stages that humans go through whilst sleeping: Stage 1, 2, 3, 4, and REM (rapid eye movement). It is possible to have dreams in the fourth stage but they happen most commonly in the last stage, REM sleep or towards the end of your sleep. â€Å"REM sleep is characterized by low-amplitude [and] fast electroencephalographic (EEG) oscillations† (Payne and Nadel). For our brains to enter REM sleep, Neurotransmitters, specifically the monoamines, have to help switch them into this stage of sleep. During REM sleep, the â€Å"activity in the aminergic system has decreased enough to allow the reticular system to escape its inhibitory influence† (Payne and Nadel). â€Å"The release from aminergic inhibition stimulates cholinergic reticular neurons in the brainstem and switches the sleeping brain into the highly active REM state, in which acetylcholine levels are as high as in the waking state† (Payne and Nadel), which allows for dreaming to occur and causes them to seem real. As said by authors: Yuval Nir and Giulio Tononi, â€Å"Perhaps the most striking feature o f conscious experiences in sleep is how altogether similar the inner world of dreams is to the real world of wakefulness. Indeed, at times the dreamer may be uncertain whether he is awake or asleep. Certainly, dreams are not created in a vacuum but closely reflect the organization and functions of our brain† (Nir and Tononi). Dreams will always be a topic that blows many people’s minds. But, with extensive studies and ongoing research, we can hopefully makes sense of it all and what they truly mean. As seen, different experts and scientists carry different viewpoints and theories on the popular questions including: why we dream, the meaning of dreams, and what happens in the brain when we’re dreaming. Although, actual evidence proves without them, our well-being wouldn’t be the same and it would affect us negatively. Annotated Bibliography Carr, Michelle. â€Å"Whats Behind Your Recurring Dreams?† Psychology Today, Sussex Publishers, www.psychologytoday.com/us/blog/dream-factory/201411/whats-behind-your-recurring-dreams. Accessed on 24 July 2019.   Ã‚  Ã‚   In â€Å"What’s Behind Your Recurring Dreams,† by Michelle Carr, we learn factual evidence of what recurring dreams mean and why they happen to begin with. She explains the common themes of recurring dreams and what they mean. I will be using this article in order to have facts about recurring dreams and what they could possibly mean. The reliability of this article is average and not the strongest because the author isn’t an expert or a PhD, but it still is backed up by citations and evidence of where the information was derived from. â€Å"Dreams: Why We Dream, Lucid Dreaming, Nightmares, Common Dreams, and More.† WebMD, WebMD, www.webmd.com/sleep-disorders/guide/dreaming-overview#1. Accessed on 24 July 2019.   Ã‚  Ã‚   In â€Å"Dreams: Why We Dream,† from WebMD, many concept involving lucid dreaming, nightmares, and common dreams humans share are explained. The article also goes into detail about the root of dreaming and why we dream to begin with. I will be using this article to explain why we dream and what that could mean to specific people. The reliability of the article is not extremely high, but it is from WebMD so it should be credible information. Although, an author is not provided. Linden, Sander van der. â€Å"The Science Behind Dreaming.† Scientific American, 26 July 2011, scientificamerican.com/article/the-science-behind-dreaming/. Accessed on 24 July 2019. In the article â€Å"The Science Behind Dreaming,†Ã‚   by Sander van der Linden, we learn details from past theories and information. The article also goes into detail about MRI methods that have been used to study dreaming and what it is. I will use this piece of writing in my report to provide scholarly evidence of what dreaming is and how it happens and to give some background information on what dreams are from a scientific standpoint. I would say the reliability of Linden’s work is fairly high due to his education and the way the article is set up. The article is very professional and provides facts backed up with his college and job information. Nir, Yuval, and Giulio Tononi. â€Å"Dreaming and the Brain: from Phenomenology to Neurophysiology.† Trends in Cognitive Sciences, U.S. National Library of Medicine, Feb. 2010, ncbi.nlm.nih.gov/pmc/articles/PMC2814941/. Accessed on 24 July 2019. In â€Å"Dreaming and the Brain: from Phenomenology to Neurophysiology,† by Yuval Nir   and Guilio Tononi, they go into great detail on the previously known information on dreams. We as well get to hear lots of studies, facts, and some theories. I will be using this article to provide details of the difference between dreaming and being awake. The reliability of this article is very credible because the authors are experts on the topic, which I found after researching the authors in order to prove reliability. Payne, Jessica D, and Lynn Nadel. â€Å"Sleep, Dreams, and Memory Consolidation: the Role of the Stress Hormone Cortisol.† Learning Memory (Cold Spring Harbor, N.Y.), Cold Spring Harbor Laboratory Press, 2004, www.ncbi.nlm.nih.gov/pmc/articles/PMC534695/. Accessed on 24 July 2019. In the article â€Å"Sleep, Dreams, and Memory Consolidation,† by Jessica Payne and Lynn Nadel, we learn about the connection between memory and dreams and how memory impacts dreams. The authors go into detail about the stages of sleep and how dreams fall into each of those categories. I will be using this text in my report to show more scientific evidence about what dreams are and how they happen during rem sleep compared to other stages of sleep. This article is very reliable because the authors are experts on the topic and have graduated from top universities. It is also reliable because it provides scientific facts with citations that follow to prove credibility.

Uses of the private browsing feature offered by major internet Essay

Uses of the private browsing feature offered by major internet browsers - Essay Example As such, other users of the same computer will not be able to track one’s communication and the pages on social sites that they have visited. Closely related to this point is that people turn on the feature when accessing sites that they do not wish their partners or family members to view, or when performing research on a subject that they consider private. For example, people accessing pornographic sites or sites that feature adult products turn on the feature to hide their tracks (lifehacker, 2012). The feature is also useful at home when planning surprises and buying gifts online (Lienjdlien, 2010). The target of the surprise is not able to detect what is in store for them as no trace of sites visited by a person is left behind. At home, the private browsing feature is also used when visiting or opening pages that are potentially dangerous or intrusive according to Lienjdlien (2010). For example, the feature may be turned on to filter out adverts or sites that may contain viruses. At work, the private browsing feature acts as a security measure against possible threats when performing online transactions (Lienjdlien, 2010). As a security measure against online threats when performing transactions, the feature is also applicable at the home. The feature is also used when one has to log onto a private account from a computer that is publicly accessed. The feature in this case prevents other persons from gaining access to private accounts once an individual has logged off from them. The feature is also important when one needs to hide their tracks and keep the computer’s browser free of information that is not relevant (Lienjdlien, 2010). Web developers enter the private mode with an aim of testing websites’ session and cookie related aspects (lifehacker, 2012). At work, one may use the private browsing feature to manage multiple accounts simultaneously on a single website. For example, if one has several gmail accounts

The Police and Criminal Evidence Act (PACE) 1984 provide sufficient Essay

The Police and Criminal Evidence Act (PACE) 1984 provide sufficient safeguards to prevent miscarriages of justice. Critically discuss whether this statement is true in relation to eyewitness testimony - Essay Example What this code does is to therefore try and safeguard the law and prevent any miscarriages of the law (Ozin, Norton and Spivey, 2006, pg. 125). A miscarriage of justice in this case refers to any punishment or even conviction of an individual for a crime that he or she did not commit (Samuels, 2014, pg. 1790). Eyewitness evidence is a very helpful source of evidence in determination of any case. However it is also a very fragile form of evidence as it is subjected to psychological evaluation by both the prosecution and defence team and this may test the credibility. The eyewitnesses are usually shaken by the different approaches taken by the two legal teams some of which are unexpected and this leads to them making mistakes or omitting important facts that lead to many juries discounting the eyewitness testimonies (Bromby, MacMillan and McKellar, 2007, pg. 340). The testimony of eyewitnesses is first of all collected by police officers once the crime is committed and recorded according to Code D of PACE. The code provides specific methods of collecting the testimony and identifying suspects which must be followed to the letter. This however is not exactly the case (Samuels, 2007, pg. 3). There are rogue police officers and others who are not so keen to follow to the letter the code according to the Act. Lack of following these specified methods and procedures is what leads to miscarriages of justice as the wrong suspects are identified and convicted of a crime they did not commit (Garrett, 2011, pg. 287). What usually happens is that the police officers lead the eye witness to a suspect by providing several descriptions which confuses the eyewitness and him or she agrees. This especially happens in cased where there is no suspect in custody already where facial identification can be made by the eye witness or even in cases

Notes on History of Dhammapada Essay Example for Free

Notes on History of Dhammapada Essay According to Wikipedia, Dhammapada is the most famous book of the Tipitakas. It is also the book that has been translated into English and other languages more times than any other book in Buddhist literature. According to Ven. K Sri Dhammananda (1988), the founder of Sudharma Buddhist Institute, Dhammapada (literally meaning The Words of Truth or The Path of Noble Truth) consists of 423 verses in Pali uttered by the Buddha on some 305 occasions for the benefit of a wide range of human beings. These sayings were selected and compiled into one book as being worthy of special note on account of their beauty and relevance for molding the lives of future generations of Buddhists. It is also surprising that according to Britannica Encyclopedia, Dhammapada is accepted both in Theravada Buddhism and in Mahayana Buddhism although there is a difference in the number of verses in the two versions. However, according to Encarta Encyclopedia, the most translated version is that of Theravada. The history of Dhammapada is also not so different in both branches of Buddhism. The Lord Buddha historically had to go round the northern India and Nepal preaching his Dhamma, meeting many people. According to the prescribed text book (Module no. A -Ya 2004) of the second year university students specializing Oriental Studies in Myanmar ), the Lord Buddha preached his Dhamma ( guides and sermons for the cessation of all the sufferings) both in the form of speech called cunniya and occasionally in poetically versed form called gatha. According to Ohn Myint , Daw (2004), the verses uttered by the Lord Buddha had been compiled by 500 Buddhist Senior Arahants in Rajaghyo, India, in the First Dhamma Council (Pathama Sangayana) in 483 BC. Venerable Buddhagosa, the most famous commentary author in Theravada Buddhism, wrote the commentary of Dhammapada named Dhammapada Atthakatha in Sri Lanka. In his commentary book, Ven. Buddha Gosa, studying thoroughly from the elderly monks and old canons, noted the historical backgrounds of the verses in Pali Language. In this book, he told the story of each verses including whom theses verses were uttered by Buddha for, where, how, when and why these verses were uttered by Lord Buddha and so on. According to Subhodha Lankara, a famous Buddhist Literary Guide throughout the history of Buddhism, the verses in Dhammapada and Buddhist Literature are composed and uttered by systematic rules of rhythm, rhyme and meter. Moreover, Thanissaro Bhikkhu (1997) writes as follows: As the Buddha himself is quoted as saying, Meter is the structural framework of verses. According to Goinka S. N, the founder of Vissapana Research Institute in India, verses in Dhammapada were just orally handed down at first before the fourth Dhamma Council held in Tambapai [Sri Lanka] in 29 B. C in which all of the Buddhist Scriptures were recorded on written forms on palm leaves. According to the Commentary of Dhammapada by Ven Buddhagosa, these verses are intentionally uttered in accordance with the listeners background knowledge, their social backgrounds, and the situations in order to enlighten their mind. As soon as the Lord uttered the verses, Ananda, the chosen attendant and constant companion of the Buddha during the last twenty-five years of his life. memorized it and handed down again to the other monks and people. According to Mahaparinibana Sutta in the first book of Suttanna Pitaka named Mahavagga, after the Lord passed into the nirvana ( His death), the senior Buddhist monks met together and held the First Buddhist Council in order to preserve the holy teachings of the Lord Buddha. In the council, all of the Buddhas teachings were divided into three parts. According to Goenka, S,N (1999), the founder of Vipassana Research Institute in India , the first part is known as the Vinaya Pitaka and it contains all the rules which Buddha laid down for monks and nuns.. The second part is called the Suttanna Pitaka and it contains the Discourses. The third part is known as the Abhidhamma Pitaka and comprises the psycho-ethical teachings of the Buddha. The first pitaka is Suttanna pitaka and it is divided into five parts according to the length and form of the discourses. The poetical verses that the Lord uttered were compiled into a book named Dhammapada. Dhammapada is included in the first part of Suttanna Pitaka named Khuddhakanikaya ( Short Discourses). According to Daw Ohn Myint, Professor of the Department of Oriental Studies, Yangon University of Distance Education ( 2004), throughout the history of Buddhism, Dhammapada has been studied and memorized by Buddhist monks. Even nowadays in Sri Lanka, the novices who want to be transformed into monkhood have to memorize all the verses in Dhammapada as a compulsory skill.

Digestive System Essay -- essays research papers

Purpose The digestive system prepares food for use by hundreds of millions of body cells. Food when eaten cannot reach cells (because it cannot pass through the intestinal walls to the bloodstream and, if it could would not be in a useful chemical state. The gut modifies food physically and chemically and disposes of unusable waste. Physical and chemical modification (digestion) depends on exocrine and endocrine secretions and controlled movement of food through the digestive tract. Mouth Mouth Food enters the digestive system via the mouth or oral cavity, mucous membrane lined. The lips (labia) protect its outer opening, cheeks form lateral walls, hard palate and soft palate form anterior/posterior roof. Communication with nasal cavity behind soft palate. Floor is muscular tongue. Tongue has bony attachments (styloid process, hyoid bone) attached to floor of mouth by frenulum. Posterior exit from mouth guarded by a ring of palatine/lingual tonsils. Enlargement sore throat, tonsillitis. Food is first processed (bitten off) by teeth, especially the anterior incisors. Suitably sized portions then retained in closed mouth and chewed or masticated (especially by cheek teeth, premolars, molars) aided by saliva Ducted salivary glands open at various points into mouth. This process involves teeth (muscles of mastication move jaws) and tongue (extrinsic and intrinsic muscles). Mechanical breakdown, plus some chemical (ptyalin, enzyme in saliva). Taste buds allow appreciation, also sample potential hazards (chemicals, toxins) Swallowing In leaving the mouth a bolus of food must cross the respiratory tract (trachea is anterior to oesophagus) by a complicated mechanism known as swallowing or deglutination which empties the mouth and ensures that food does not enter the windpipe. Swallowing involves co-ordinated activity of tongue, soft palate pharynx and oesophagus. The first (buccal) phase is voluntary, food being forced into the pharynx by the tongue. After this the process is reflex. The tongue blocks the mouth, soft palate closes off the nose and the larynx rises so that the epiglottis closes off the trachea. Food thus moves into the pharynx and onwards by peristalsis aided by gravity. If we try to talk whilst swallowing food may enter the respiratory passages and a cough reflex expels the bolus. Oesophagus The oesophagus (about 10") is the first part of the... ...a mixture of mucus and serous fluids, each produced to various extent in various glands. Also contains salivary amylase, (starts to break down starch) (antibacterial) and antibodies. In some mammals (and snakes!) saliva may be poisonous, quieting down living prey. Pancreas Endocrine and exocrine gland. Exocrine part produces many enzymes which enter the duodenum via the pancreatic duct. Endocrine part produces insulin, blood sugar regulator. Liver and gallbladder Bile, a watery greenish fluid is produced by the liver and secreted via the hepatic duct and cystic duct to the gall bladder for storage, and thence on demand via the common bile duct to an opening near the pancreatic duct in the duodenum. It contains bile salts, bile pigments (mainly bilerubin, essentially the non-iron part of hemoglobin) cholesterol and phospholipids. Bile salts and phosholipds emulsify fats, the rest are just being excreted. Gallstones are usually cholesterol based, may block the hepatic or common bile ducts causing pain, jaundice. Liver Multi functional: important in this context since the capillaries of the small intestine drain fat and other nutrient rich lymph into it via the hepatic portal system.

Humanities Is

Webster s Dictionary defines humanities as the branches of learning concerned with human thought and relations. Products of human invention and genius that express human emotions are shown through literature, visual arts, and performing arts. Studying humanities has a value, it is a necessity of life, and it serves mankind. Literature has allowed writers to achieve realism in which they would reflect on day-to-day events of real life rather than describing the imaginary world. Writer s discovered that they could do justice to the problems society was facing by using a more naturalistic style and using realistic terms. There were a number of themes that were touched by writers during the age in which they belonged to. Novelist Charles Dickens used his books to explore the social injustices and its effects that they have incurred on individuals. In A Tale of Two Cities, Dickens has the readers experience the reconstruction of the French Revolution and in Oliver Twist he discussed the treatment of the poor in workhouses. On the other side of society, poet William Wordsworth explored the theme of relationships between human beings and the world of nature. In Wordsworth poem, Tintern and Abbey, he writes about how important nature is to him and how it has allowed him to have other relationships with other human beings. Art is all around us, but we still seem to fail by recognizing how much society is constructed from it. Art can be used to make a statement about who we are and what we value without even saying a word. Art can be quite difficult to interpret because it is complex, can be viewed by different cultures, and/or within a different age. The history of art is shown by how artists used their minds and imaginations. Leonardo da Vinci constantly searched his mind looking for answers about the world and its crucial parts. He became concerned with mathematics, a deep respect for the natural world, and a love for beauty all intertwined with the feeling of emotional power, which was found in his painting The Last Supper. The skepticism of da Vinci was also found in the mind of Michelangelo. The sculpture David, by Michelangelo, is photographically realistic and has a clear statement of idealized beauty. David was a symbolic emblem with civic power to the city outside the Palazzo Vecchio.