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The AstronomersMost Recent Videos
Most Recent Extragalactic astronomy videos
Videos 1-25 of 92
 
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Most Distant Object in the Universe: Gamma Ray Burst GRB 090423

"Scientists say a faint burst of radiation discovered last week is the remnant of a massive stellar explosion that took place more than 13 billion years ago, or only about 630 million years after the big bang. The gamma-ray burst, dubbed GRB 090423, points to what astronomers are calling the most distant object in the universe. Gamma rays are the highest-energy wavelength of light produced when high-energy particles collide. The large-scale gamma-ray bursts are believed to be produced when massive stars collapse into black holes, releasing jets of gas that react and heat up the gas surrounding the dying star. Astronomers on Tuesday said they believe the gamma-ray burst discovered is the result of such a stellar explosion. NASA's Swift satellite first spotted the 10-second-long burst on April 23, but could not see any corresponding visible light to match it. This suggested the burst occurred in an early time of the universe some 13 billion years ago, when dense clouds of hydrogen gas completely absorbed visible light, obscuring our view of a time when scientists believe the first stars and galaxies were born. Subsequent examinations of the gamma-ray burst were taken from two ground-based telescopes located on Mauna Kea, Hawaii: the United Kingdom Infrared Telescope and the Gemini North telescope. Redshift signals far-off origin Astronomers using these telescopes were able to look at the burst's infrared light afterglow to determine the distance of the explosion based on its redshift, or how much the light's wavelength had stretched towards the red end of the spectrum in response to the expansion of the universe. Just as the sound of a radio from a car moving away from us sounds stretched out, so too does light shift to a longer wavelength as its source moves farther away. Since the universe is expanding, faraway objects are moving away at a faster rate than those closer to us, and so their redshift is correspondingly higher. The examination of the afterglow confirmed the burst's redshift of 8.2, the highest ever recorded. This corresponds to a distance of 13.035 billion light-years. "This new gamma-ray burst smashed all the records," said Edo Berger, a professor at Harvard University and one of the scientists that first demonstrated the burst's origin. "It easily surpassed the most distant galaxies and quasars. In fact, it showed that we can use these spectacular events to pinpoint the first generation of stars and galaxies," he said in a statement." (http://www.cbc.ca/technology/story/2009/04/28/distant-universe-gamma-ray.html)

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19. Omega and the End of the Universe

Frontiers/Controversies in Astrophysics (ASTR 160) Class begins with a review of the issues previously addressed about the origin and fate of the universe. The role of gravity in the expansion of the universe is discussed and given as the reason why the rate of expansion cannot remain constant and will eventually slow down. The actual density of the universe is calculated using various methods. Finally, the unsolved problem of dark matter is addressed and two explanatory hypotheses are proposed. One is that the universe is comprised of WIMPs (Weakly Interactive Massive Particles) that fulfill two requirements: they have mass and do not interact with light. The second hypothesis is that dark matter is made of MACHOs (Massive Astrophysical Compact Halo Objects), which scientists have attempted to identify through gravitational lenses. 00:00 - Chapter 1. Review of Issues in Cosmology 08:28 - Chapter 2. Determining Mass 26:39 - Chapter 3. Dark Matter: WIMPs? 37:30 - Chapter 4. Dark Matter: MACHOs? Complete course materials are available at the Open Yale Courses website: http://open.yale.edu/courses This course was recorded in Spring 2007.

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06:23
 
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06:23

Ultimate fate of our Universe

Its a final part of a documentary entitled Time, presented by Michio Kaku and showed by BBC in 2006. That particular part shows a theory about the ultimate fate of the Universe.

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07:34
 
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Hubble Targeting The Big Questions

The NASA/ESA Hubble Space Telescope is working on three of the most ambitious projects in its history just now. These multicycle treasury programs are using Hubble's unique ability to observe across the spectrum from ultraviolet, through visible, to infrared light, to build up a library of data which will serve astronomers for many years. After circling the Earth for over two decades, Hubble has been responsible for many fascinating scientific discoveries. After the visit by astronauts in 2009 to service the spacecraft and to install new instruments, the telescope is now at the height of its powers. As the observatory has matured, attention has turned to some ambitious projects on a scale that would not have even been considered a few years ago. Between them, these projects could help answer some of the biggest questions in astronomy today, and will contribute to science for many years to come. Now, observing time on Hubble is a very precious commodity and it's hugely sought after. That means that when astronomers want to use Hubble, they have to apply for observing time. And in their application, they have to be very detailed about what it is exactly they want to study, and how they're going to do it. Now this process works just fine for the vast majority of projects which usually have very focused scientific goals. However, once in a while, Hubble gets used for something much bigger, with much broader scientific goals. And in these cases, the normal way of handing out time just isn't quite enough. And rather of being tied to the research question of individual scientists, like Hubble observations usually are, the multicycle treasury programs are designed to create a treasure trove of data which can be used by as many people as possible in their work. For example, the Panchromatic Hubble Andromeda Treasury program is working on a detailed map of part of the nearby Andromeda Galaxy, going from its bright core to the wispy ends of its spiral arms. Andromeda is actually the closest spiral galaxy to the Milky Way and it gives us an unparalleled view of the structure of a galaxy somewhat similar to our own. It's actually quite big in the sky - several times the size of the full moon, but it's so faint that it's barely visible with the naked eye, even on a very dark night. For Hubble, though, it's ablaze with stars - and an estimated 100 million of them will have been mapped by the time the survey is complete. The survey won't just be plotting their position, but taking detailed color information in visible, near infrared and ultraviolet light - something no other telescope can do. Accurately measuring the colors of stars is vital for studying many of their properties, for example their surface temperature. With this abundance of data, scientists will be making discoveries in the Andromeda Galaxy for a long time. Another of these Hubble treasury programs is looking far back into the evolution of our Universe. And that's the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey... or CANDELS for short. By scanning large, dark areas of sky with very few foreground stars in them, this survey is is looking beyond the confines of our cosmic neighborhood and into the farthest reaches of the Universe. They're observing galaxies that are so far away that their light has taken billions of years to reach us. This allows astronomers to study the distant past of the cosmos and how galaxies have evolved over time. Studying galaxy clusters is key to explaining two of the big mysteries of modern astronomy, dark matter and dark energy. Studying normal matter in the Universe, like stars or gas clouds, is relatively easy because it emits or absorbs light. However, it turns out that most of the matter in the Universe is not in fact normal but rather so-called dark matter, which doesn't give off any radiation whatsoever. Now, astronomers don't really know what dark matter is. But by looking at how these clusters bend light from distant galaxies in the background allows us to reconstruct a map of how the dark matter is distributed inside these clusters. The CLASH survey is also going to study distant supernovae. This is going to probe the expansion rate of the Universe and help us understand the mystery of why this expansion is accelerating. In fact there are already discoveries being made with the first data released from this survey. In April of this year, a new study identified a faraway galaxy imaged by the gravitational lens in Abell 383 - the first of 25 to be mapped by this survey. Thanks to the cluster amplifying the light from this distant galaxy, astronomers were able to make much more detailed observations than would otherwise have been possible. And they discovered that the stars in this galaxy were surprisingly old: they must have been born just a few hundred million years after the Big Bang, much earlier than expected.

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Cosmic Inflation and the Accelerating Universe - Part 2

Alan H. Guth describes the theory of inflation and presents evidence that indicates our universe very likely underwent a perod of inflation in its early existence. He also discusses the surprising observation that the expansion of the universe is accelerating, offers possible explanations for this acceleration, and describes its impact on particle physics. http://www.meta-library.net/cq-guth/evide-frame.html

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Speed of Light Explained

Variable Speed of Light An observer outside gravitational fields measures the speed of light locally (in his location) at 299792.458 km/s but when he looks towards a black hole he sees the speed of light there to be as slow as a few meters/s. At the same time an observer freefalling into that black hole measures the speed of light locally (in his location) at 299792.458 km/s; when he looks towards the black hole he sees the speed of light there much slower; when he looks away from the black hole he sees the speed of light there much faster. When he looks towards outside gravitational fields he sees the speed of light there a zillion km/s. In 1915 (10 years after Special Relativity) Einstein developed another theory called General Relativity that deals with gravitational fields and according to this latest theory the speed of light appears to vary with the intensity of the gravitational field. Learn More... Effective Speed of Light Scientists just confirmed the existence of "Dark Energy", a mysterious repulsive force that acts in opposite to gravity. Scientists today do not know what this "Dark Energy" is but they know that it is causing the entire universe to expand at an increasing rate. This Dark Energy is even causing distant galaxies to recede from us faster than our local speed of light. The expansion of the universe is causing light en route to be dragged away from us. This makes observers to see distant inbound light at effective speeds less than 299792.458 km/s and to see distant outbound light at effective speeds greater than 299792.458 km/s. However every non-accelerating observer measures the speed of light locally (in his location) at 299792.458 km/s in any direction. Learn More... Speed of Light = 12000 Lunar Orbits/Earth Day But 1400 years ago it was stated in the Quran (Koran, the book of Islam) that angels travel in one day the same distance that the moon travels in 1000 lunar years, that is, 12000 Lunar Orbits / Earth Day. Outside the gravitational field of the sun 12000 Lunar Orbits / Earth Day turned out to be the local speed of light!!! This definition is independent of direction and common to all observers: An observer near a black hole, for example, sees the speed of light outside gravitational fields a zillion km/s but still equal to 12000 Lunar Orbits / Earth Day!!!

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08:58
 
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the collapse of the universe

The ultimate fate of the universe is a topic in physical cosmology. Many possible fates are predicted by rival scientific theories, including futures of both finite and infinite duration. Once the notion that the universe started with a rapid inflation nicknamed the Big Bang became accepted by the majority of scientists,[1] the ultimate fate of the universe became a valid cosmological question, one depending upon the physical properties of the mass/energy in the universe, its average density, and the rate of expansion. ========================================= http://en.wikipedia.org/wiki/Ultimate_fate_of_the_universe ========================================= Our support by joining us on Facebook http://www.facebook.com/islammtruth

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Views: 391 | Comments: 0

 
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Mysteries of a Dark Universe

Watch this video commercial free on the SpaceRip app, available in the Apple and Google Play stores. DARK ENERGY in Full HD 1080p. Cosmology, the study of the universe as a whole, has been turned on its head by a stunning discovery that the universe is flying apart in all directions at an ever-increasing rate. Is the universe bursting at the seams? Or is nature somehow fooling us? The astronomers whose data revealed this accelerating universe have been awarded the Nobel Prize for Physics. And yet, since 1998, when the discovery was first announced, scientists have struggled to come to grips with a mysterious presence that now appears to control the future of the cosmos: dark energy. On remote mountaintops around the world, major astronomical centers hum along, with state of the art digital sensors, computers, air conditioning, infrastructure, and motors to turn the giant telescopes. Deep in Chile's Atacama desert, the Paranal Observatory is an astronomical Mecca. This facility draws two megawatts of power, enough for around two thousand homes. What astronomers get for all this is photons, tiny mass-less particles of light. They stream in from across time and space by the trillions from nearby sources, down to one or two per second from objects at the edge of the visible universe. In this age of precision astronomy, observers have been studying the properties of these particles, to find clues to how stars live and die, how galaxies form, how black holes grow, and more. But for all we've learned, we are finding out just how much still eludes our grasp, how short our efforts to understand the workings of the universe still fall. A hundred years ago, most astronomers believed the universe consisted of a grand disk, the Milky Way. They saw stars, like our own sun, moving around it amid giant regions of dust and luminous gas. The overall size and shape of this "island universe" appeared static and unchanging. That view posed a challenge to Albert Einstein, who sought to explore the role that gravity, a dynamic force, plays in the universe as a whole. There is a now legendary story in which Einstein tried to show why the gravity of all the stars and gas out there didn't simply cause the universe to collapse into a heap. He reasoned that there must be some repulsive force that countered gravity and held the Universe up. He called this force the "cosmological constant." Represented in his equations by the Greek letter Lambda, it's often referred to as a fudge factor. In 1916, the idea seemed reasonable. The Dutch physicist Willem de Sitter solved Einstein's equations with a cosmological constant, lending support to the idea of a static universe. Now enter the American astronomer, Vesto Slipher. Working at the Lowell Observatory in Arizona, he examined a series of fuzzy patches in the sky called spiral nebulae, what we know as galaxies. He found that their light was slightly shifted in color. It's similar to the way a siren distorts, as an ambulance races past us. If an object is moving toward Earth, the wavelength of its light is compressed, making it bluer. If it's moving away, the light gets stretched out, making it redder. 12 of the 15 nebulae that Slipher examined were red-shifted, a sign they are racing away from us. Edwin Hubble, a young astronomer, went in for a closer look. Using the giant new Hooker telescope in Southern California, he scoured the nebulae for a type of pulsating star, called a Cepheid. The rate at which their light rises and falls is an indicator of their intrinsic brightness. By measuring their apparent brightness, Hubble could calculate the distance to their host galaxies. Combining distances with redshifts, he found that the farther away these spirals are, the faster they are moving away from us. This relationship, called the Hubble Constant, showed that the universe is not static, but expanding. Einstein acknowledged the breakthrough, and admitted that his famous fudge factor was the greatest blunder of his career.

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Gravitational clustering as a result of particle expansion

Visit http://www.avantgravity.com/3d_expansion_crosseye.html for an updated, higher-res version of this animation. A visual experiment to see what happens when an array of physically proximate particles begin expanding: Individual particles expand into one another and eventually form stable clusters, bound by the outward pressure of their expansion. Those stable clusters would continue to expand into one another to form larger superstructures of wildly varying size and complexity. For the next 13.7 billion years, every physical object in our universe would be composed of snowballing clusters and superstructures of expanding particles, that would continue expanding right along with the rest of the rapidly inflating universe. In fact, if everything were made up of particles expanding at the same rate, then from within the universe it might be nearly impossible to tell that the expansion was happening at all, but expansion at a particle level would be driving the expansion at a cosmic level. Now remember that we are a part of the framework we observe, so every person would be made up of those same expanding particles, and all we would directly observe is the appearance of large masses moving towards one another. At the tiniest scales, this effect might look a great deal like the strong nuclear force. At larger orders of magnitude, it would look a lot like gravity.

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07:43
 
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Astronomy: Dark Matter and Dark Energy

Dark Matter, In astronomy and cosmology, dark matter is a form of matter that is undetectable by its emitted electromagnetic radiation, but whose presence can be inferred from gravitational effects on visible matter and background radiation. According to present observations of structures larger than galaxies, as well as Big Bang cosmology, dark matter accounts for the vast majority of the mass in the observable universe. Dark Energy: In physical cosmology, astronomy and celestial mechanics, dark energy is a hypothetical form of energy that permeates all of space and tends to increase the rate of expansion of the universe. Dark energy is the most popular way to explain recent observations and experiments that the universe appears to be expanding at an accelerating rate. In the standard model of cosmology, dark energy currently accounts for 74% of the total mass-energy of the universe.

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06:53
 
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Dark Matter & Dark Energy,good

Beautiful orrery(solar system model) avaiable in : http://www.orrerystore.com/ .Neil deGrasse Tyson offers one of the simplest, most straightforward summaries of one of the greatest challenges and questions facing modern Science today.In astronomy and cosmology, dark matter is a hypothetical form of matter that is undetectable by its emitted electromagnetic radiation, but whose presence can be inferred from gravitational effects on visible matter. According to present observations of structures larger than galaxies, as well as Big Bang cosmology, dark matter and dark energy could account for the vast majority of the mass in the observable universe.In physical cosmology, astronomy and celestial mechanics, dark energy is a hypothetical form of energy that permeates all of space and tends to increase the rate of expansion of the universe. Dark energy is the most popular way to explain recent observations and experiments that the universe appears to be expanding at an accelerating rate. In the standard model of cosmology, dark energy currently accounts for 74% of the total mass-energy of the universe.Dr. Neil deGrasse Tyson is an American astrophysicist and the Frederick P. Rose Director of the Hayden Planetarium at the American Museum of Natural History in New York City. An accomplished scientist, he is also outspoken for his rationalist and skeptical world-views, and was honored with the 2009 Isaac Asimov award from the American Humanist Association.To find out more about Dr. Tyson, you can start here:http://www.haydenplanetarium.org/tyson/To read more about Dark Matter and Dark Energy, you can start here:http://en.wikipedia.org/wiki/Dark_matterhttp://en.wikipedia.org/wiki/Dark_Energyhttp://hubblesite.org/hubble_discoveries/dark_energy/http://www.dmoz.org/Science/Astronomy/Cosmology/Dark_Matter/To read more about the Theory of Special Relativity, you can start here:http://www.phys.unsw.edu.au/einsteinlight/http://www.einstein-online.info/en/elementary/index.htmlhttp://en.wikipedia.org/wiki/Special_relativityTo read more about the Theory of General Relativity, you can start here:http://www.einstein-online.info/en/elementary/generalRT/index.htmlhttp://en.wikipedia.org/wiki/General_relativityTo read more about "real-life" applications of Relativity, you can start here:http://www.einstein-online.info/en/spotlights/complete_spotlights/index.htmlTo check a quick summary chart of the Standard Model, you can click here:http://twitwall.com/view/?what=0608060B00To check an interactive tour of Particle Physics, you can click here:http://particleadventure.org/To read excellent introduction into Particle Physics, you can start here:http://en.wikipedia.org/wiki/Standard_Modelhttp://www.kuro5hin.org/story/2002/5/1/3712/31700http://cms.web.cern.ch/cms/Physics/StandardPackage/index.htmlTo read glossaries for Quantum Physics terms, you can start here:http://www.quantum-physics.polytechnique.fr/http://www.sparknotes.com/testprep/books/sat2/physics/chapter19section3.rhtmlTo read introductory articles on Quantum Physics, you can start here:http://www.newscientist.com/topic/quantum-worldhttp://www.lightandmatter.com/html_books/6mr/ch01/ch01.htmlhttp://www.sciencedaily.com/news/matter_energy/quantum_physics/http://www.quantiki.org/wiki/index.php/Introduction_to_Quantum_TheoryTo take free online college-level courses, you can start here:http://ocw.mit.edu/OcwWeb/Physics/index.htmhttp://ocw.mit.edu/OcwWeb/Chemistry/index.htmThis clip was edited from the 'Cosmic Quandaries with Dr. Neil deGrasse Tyson' lecture held at The Palladium in St. Petersburg's College, March 26th, 2009. http://www.spcollege.edu/You can watch the entire lecture here:http://www.youtube.com/watch?v=CAD25s53wmE

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01:21:27
 
01:21:27
 
01:21:27

Cosmology, the Universe, & Evolution

Theoretical physicist Lawrence M. Krauss joined John B. Wells (email) to discuss the origin of the universe and how it could have arisen from nothing. "We now can see a plausible way in which a universe can come from absolutely nothing without any creator," he said, adding that the aspects of our universe which can be measured are consistent with that conclusion. The word 'nothing' is a scientific term (not a philosophical one) that refers to empty space, or an area with zero total particles, Krauss noted. This space is not actually empty but is instead "a boiling bubbling brew of virtual particles—particles that fall in and out of existence at a time scale so short that you can't measure them," he explained. Space can pop in and out of existence and is where the dominant energy of the universe resides, Krauss revealed. The very laws governing the universe may have arisen spontaneously as well, and may be completely different in other universes, he added. Krauss spoke about the difference between science and philosophy/religion, pointing out the unique role of science in probing empirical information about the world. While he believes it is presumptuous to say categorically, "There is no God," Krauss admitted there is no physical proof to suggest such a being exists. He further asserted that there is no evidence for intelligent design in biological life and in the universe. The Earth is teaming with diverse life forms of all different kinds, none of them designed, Krauss said. The amazing diversity of life on this planet arose solely by natural evolutionary mechanism without any celestial guidance, he declared. Krauss also talked about how dark energy may dominate the future of the universe, causing it to expand at a rate faster than the speed of light, as well as his expectation that Earth-like planets will be discovered within our lifetime, and perhaps some will even have life on them. Biography: Prof. Lawrence M. Krauss is an internationally known theoretical physicist with wide research interests, including the interface between elementary particle physics and cosmology, where his studies include the early universe, the nature of dark matter, general relativity and neutrino astrophysics. He has investigated questions ranging from the nature of exploding stars to issues of the origin of all mass in the universe. Wikipedia There are two very different senses in which the term Cosmology is used. Physical cosmology is the scholarly and academic study that seeks to understand the origin, evolution, structure, and ultimate fate of the universe at large, as well as the natural laws that keep it in order.[1] The subject matter of this field is studied using scholarly methodology, including the scientific method and reason. It is studied by scientists, such as astronomers, and theoretical physicists; and academic philosophers, such as metaphysicians, philosophers of physics, and philosophers of space and time. Modern cosmology is dominated by the Big Bang theory, which attempts to bring together observational astronomy and particle physics.[2] In contrast, religious cosmology (or mythological cosmology) is study in the humanities, of the historical, mythological, religious, and esoteric literature and theories about eschatology (i.e. the end of the world), including such theories, as for instance apocalypticism. Although the word cosmology is recent (first used in 1730 in Christian Wolff's Cosmologia Generalis), the study of the universe has a long history involving science, philosophy, esotericism and religion. Related studies include cosmogony, which focuses on the origin of the Universe, and cosmography, which maps the features of the Universe. Cosmology is also connected to astronomy. However, they are contrasted in that while the former is concerned with the Universe as a whole, the latter deals with individual celestial objects. Disciplines In recent times, physics and astrophysics have played a central role in shaping the understanding of the universe through scientific observation and experiment. What is known as physical cosmology shaped through both mathematics and observation the analysis of the whole universe. It is generally understood to begin with the Big Bang, followed almost instantaneously by cosmic inflation - an expansion of space from which the universe is thought to have emerged ~13.7±0.2×109 (roughly 13.5--13.9 billion) years ago.[3] Physical cosmologists propose that the history of the universe has been governed entirely by physical laws. Between the domains of religion and science stands the philosophical perspective of metaphysical cosmology. This ancient field of study seeks to draw intuitive conclusions about the nature of the universe, man, a supernatural creator, and/or their relationships based on the extension of some set of presumed facts borrowed from spiritual experience and/or observation.

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06:33
 
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Finely Tuned Universe

"If the rate of expansion one second after the big bang had been smaller by even one part in a hundred thousand million million, the universe would have recollapsed before it ever reached its present size." Stephen Hawking, A Brief History Of Time, Bantam Press, London: 1988, p. 121-125 *********** And this was JUST the beginning. *********** Please see the details now. http://www.creationofuniverse.com

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The Inflation of the Universe

A short 2 minute compilation of animation visualizing what inflation and expansion of the universe might look like from an "outside" observer. It is designed to be used by teachers and students of Astronomy or Earth Science as a short visual summary of the concept. Subscribe to my channel for other video trailers in Astronomy and Biology. I will be releasing new ones periodically. I wish to thank all of the video and music producers whose postings enabled me to create this video for educational use. Please rate this video and feel free to comment. If you like it, please help me spread the word. The more students who can enjoy these dramatic videos, the better!

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01:18:41
 
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01:18:41

Our Universe with Sean Carroll

Art spoke with physicist Sean Carroll about the origin and nature of the universe we live in. Carroll discussed the Big Bang, a scientific theory which proposes the universe came about from a tremendously dense and hot state about 14 billion years ago. He provided evidence for this theory, pointing out that the Big Bang model has been "established beyond reasonable doubt." Carroll covered other cosmological and theoretical physics topics, including the accelerating expansion of the universe, how space and time came into existence, 'quantum gravity,' parallel universes, string theory, and time travel. He also talked about the recent discovery of an Earth-like planet orbiting a red dwarf star 20 light-years away from our solar system. Carroll said it was unlikely there would be the kind of life there that we could find by using radio telescopes. Biography: Sean Carroll is a Senior Research Associate in Physics at the California Institute of Technology. His research involves theoretical physics and astrophysics, focusing on issues in cosmology, field theory, and gravitation. His current research involves models of dark matter and dark energy, cosmological modifications of Einstein's general relativity, the physics of inflationary cosmology, and the origin of time asymmetry. He has received research grants from NASA, the Department of Energy, and the National Science Foundation, as well as fellowships from the Sloan and Packard foundations. Wikipedia The universe is commonly defined as the totality of existence, including planets, stars, galaxies, the contents of intergalactic space, and all matter and energy. Definitions and usage vary and similar terms include the cosmos, the world and nature. Scientific observation of earlier stages in the development of the universe, which can be seen at great distances, suggests that the universe has been governed by the same physical laws and constants throughout most of its extent and history. The universe is believed to be at least 10 billion light years in diameter and has existed for about 13.7 billion years, since it was created by the Big Bang. There are various multiverse hypotheses, in which physicists have suggested that the universe might be one among many universes that likewise exist. The farthest distance that it is theoretically possible for humans to see is described as the observable universe. Observations have shown that the universe appears to be expanding at an accelerating rate, and a number of models have arisen to predict its ultimate fate. The universe is immensely large and possibly infinite in volume. The region visible from Earth (the observable universe) is a sphere with a radius of about 46 billion light years, based on where the expansion of space has taken the most distant objects observed. For comparison, the diameter of a typical galaxy is only 30,000 light-years, and the typical distance between two neighboring galaxies is only 3 million light-years. As an example, our Milky Way Galaxy is roughly 100,000 light years in diameter, and our nearest sister galaxy, the Andromeda Galaxy, is located roughly 2.5 million light years away. There are probably more than 100 billion (1011) galaxies in the observable universe. Typical galaxies range from dwarfs with as few as ten million (107) stars up to giants with one trillion (1012) stars, all orbiting the galaxy's center of mass. A 2010 study by astronomers estimated that the observable universe contains 300 sextillion (3×1023) stars. The universe is believed to be mostly composed of dark energy and dark matter, both of which are poorly understood at present. Less than 5% of the universe is ordinary matter, a relatively small contribution. The observable matter is spread homogeneously (uniformly) throughout the universe, when averaged over distances longer than 300 million light-years. However, on smaller length-scales, matter is observed to form "clumps", i.e., to cluster hierarchically; many atoms are condensed into stars, most stars into galaxies, most galaxies into clusters, superclusters and, finally, the largest-scale structures such as the Great Wall of galaxies. The observable matter of the universe is also spread isotropically, meaning that no direction of observation seems different from any other; each region of the sky has roughly the same content. The universe is also bathed in a highly isotropic microwave radiation that corresponds to a thermal equilibrium blackbody spectrum of roughly 2.725 kelvin. The hypothesis that the large-scale universe is homogeneous and isotropic is known as the cosmological principle, which is supported by astronomical observations. The present overall density of the universe is very low, roughly 9.9 × 10−30 grams per cubic centimetre. This mass-energy appears to consist of 73% dark energy, 23% cold dark matter and 4% ordinary matter.Thus the density of atoms is on the order of a single hydrogen atom for every four cubic meters of volume.

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02:21
 
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Zeroing in on Hubble's constant

Date- 5th Jan 09 Source- http://www.ciw.edu/multimedia_content 'In the early part of the 20th Century, Carnegie astronomer Edwin Hubble discovered that the universe is expanding. The rate of expansion is known as the Hubble constant. Its precise value has been hotly debated for all of the 80 intervening years. The value of the Hubble constant is a key ingredient in determining the age and size of the universe.' More info- http://www.ciw.edu/news/zeroing_hubble_s_constant

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04:26
 
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04:26

Across the universe - hubble deep field

The Universe defined as everything that physically exists: the entirety of space and time, all forms of matter, energy and momentum, and the physical laws and constants that govern them. However, the term "universe" may be used in slightly different contextual senses, denoting such concepts as the cosmos, the world or Nature. Astronomical observations indicate that the universe is 13.73 ± 0.12 billion years old and at least 93 billion light years across. The theoretical event that started the universe is called the Big Bang. At this point in time all matter and energy of the observable universe was concentrated in one point of infinite density. After the Big Bang the universe started to expand to its present form. Since special relativity states that matter cannot exceed the speed of light, in a fixed space-time, it may seem paradoxical that two galaxies can be separated by 93 billion light years in 13 billion years; however, this separation is a natural consequence of general relativity. Stated simply, space can expand with no intrinsic limit on its rate; thus, two galaxies can separate more quickly than the speed of light if the space between them grows. Experimental measurements such as the redshifts and spatial distribution of distant galaxies, the cosmic microwave background radiation, and the relative percentages of the lighter chemical elements, support this theoretical expansion and, more generally, the Big Bang theory, which proposes that space itself was created ex nihilo at a specific time in the past. Recent observations have shown that this expansion is accelerating, and that most of the matter and energy in the universe is fundamentally different from that observed on Earth and not directly observable (cf. dark energy). The imprecision of current observations has hindered predictions of the ultimate fate of the universe. Experiments suggest that the universe has been governed by the same physical laws and constants throughout its extent and history. The dominant force at cosmological distances is gravity, and general relativity is currently the most accurate theory of gravitation. The remaining three fundamental forces and the particles on which they act are described by the Standard Model. The universe has at least three dimensions of space and one of time, although extremely small additional dimensions cannot be ruled out experimentally. Spacetime appears to be smoothly and simply connected, and space has very small mean curvature, so that Euclidean geometry is accurate on the average throughout the universe. According to some speculations, this universe may be one of many disconnected universes, which are collectively denoted as the multiverse. In one theory, there is an infinite variety of universes, each with different physical constants. In another theory, new universes are spawned with every quantum measurement. By definition, these speculations cannot currently be tested experimentally. Throughout recorded history, several cosmologies and cosmogonies have been proposed to account for observations of the universe. The earliest quantitative models were developed by the ancient Greeks, who proposed that the universe possesses infinite space and has existed eternally, but contains a single set of concentric spheres of finite size - corresponding to the fixed stars, the Sun and various planets - rotating about a spherical but unmoving Earth. Over the centuries, more precise observations and improved theories of gravity led to Copernicus' heliocentric model and the Newtonian model of the solar system, respectively. Further improvements in astronomy led to the characterization of the Milky Way, and the discovery of other galaxies and the microwave background radiation; careful studies of the distribution of these galaxies and their spectral lines have led to much of modern cosmology. enjoy the view!!! =)

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05:27
 
05:27
 
05:27

Bathrooms and Bubble Universes

See more clips at http://worldsciencefestival.com/wsftv Before coming to the conclusion that there are multiple universes, scientists first had to work out how their one universe worked. One puzzling aspect was the observation of inconsistencies in the rate of expansion, as if some parts of the universe were growing at a different rate than the rest. Andrei Linde, a professor of physics at Stanford University describes how a late night epiphany set the framework for both the Chaotic Inflationary Theory and a comedic tale of restroom inspiration.

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03:00
 
03:00
 
03:00

The Big Bang Theory Explained The Simple Way

The Big Bang explains how the universe expanded from a single point. The Big Bang occurred 13.7 billion years ago. All the matter, energy, and light; were all compacted into an infinitely dense point. The universe then expanded tremendously. As the seconds passes; this condensed energy was spread out, and the forces such as gravity can into existence. Around 300,000 years after the Big Band, the universe was abundant with floating particles. These particles then slowly came to each other. The most simplest elements came into existence, most found was hydrogen (with 1 proton) and helium (with 2 protons). The different atoms were able to form and then these particles became more and more condensed. Soon matter was formed. The early stars were made up of very simple elements and so they had very short lifespans of only millions of years. But the nuclear fusion in the cores' of these early stars slowly created heavier elements; which when the star died, would become a part of a new star. These stars were created in small groups and attracted other stars. These stars were grouped in irregular shapes. Then the different shapes merged to form the first galaxies. Then as more galaxies formed, they became grouped in galaxy clusters, and then these clusters were contained in super clusters. Today, scientist know about a force called dark energy. Dark energy acts like an anti-gravity and does the opposite of gravity. Dark energy is currently the cause of the expansion of the universe. The universe is expanding at an accelerating rate today. With the discovery of dark energy, many scientist now believe the the universe will continue to expand forever and all of the matter in the universe will eventually decay within a trillion years. Free Music from: www.Music4YourVids.co.uk Song on this video: Headding For The Battle Website: http://www.gphhawkinsrationalistsociety.weebly.com/ My Facebook Page: https://www.facebook.com/pages/Gphhawkins/246909378669578 Podcast: http://www.blogtalkradio.com/gphhawkins Tweet with me: http://www.twitter.com/gphhawkins Ustream: http://www.ustream.com/channel/gphhawkins

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01:26
 
01:26
 
01:26

Teach Astronomy - Cosmological Principle

http://www.teachastronomy.com/ A very basic assumption about the universe which forms the basis for modern cosmology is called the cosmological principle, that the universe is isotropic and homogeneous. Isotropic means the same in all directions. This means that in any direction we look we tend to see the same structures and numbers of galaxies, and that is in fact confirmed by observation. It also means that the Hubble expansion is the same in every direction we look, that the expansion rate is smooth and not faster in one direction of the sky than in another direction, and this is also confirmed by observations. The second part of the cosmological principle, the homogeneity of space, is much more difficult to test because as we look out in space we look back in time. So when we view distant parts of the universe we are viewing parts of the universe as they were earlier when the universe was smaller, but we can basically test the idea by showing that the universe contains more or less the same structures everywhere we look and that on the largest scales, over a hundred megaparsecs or three hundred million light years, the average amount of material in any volume of space from one direction to the other is about the same. So the universe is indeed smooth on the very largest scales.

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05:42
 
05:42
 
05:42

What different aspects make up the Grand Unified Theory of the universe?

The panel discusses: Grand Unified Theory. Cosmic microwave background radiation. Dark matter. Type 1A supernova. Expansion rate of the universe. The Cosmological Constant. Large Synoptic Survey Telescope. Micro-lensing. Large Hadron Collider. The standard model of cosmology. Higgs-Boson. Super Symmetry.

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36:51
 
36:51
 
36:51

Fred Adams: Expanding Universe Conference (http://www.lowell.edu/workshops/slipher)

Title: The FUTURE History of Cosmic Expansion (and constituent astrophysical objects) Abstract: The discovery of the cosmic expansion had a profound influence on our understanding of the past history of the universe. This talk outlines the future history of the cosmos as it continues to expand: we consider the evolution of planets, stars, galaxies, and the universe itself over time scales that greatly exceed the current cosmic age. The discussion starts with the effects of accelerated cosmic expansion, which causes every galaxy cluster to become its own island universe. Within these bound structure, the lowest mass stars continue to burn hydrogen over much longer times, and evolve off the main-sequence near the epoch when conventional star formation ends. The stellar population is thus converted into degenerate remnants -- neutron stars, white dwarfs, and brown dwarfs. Although the supply of interstellar gas grows depleted, star formation continues at an attenuated rate through brown dwarf collisions. As the galaxy evaporates via dynamical relaxation, dark matter particles are accreted by white dwarfs, where they annihilate and keep the stellar remnants relatively warm. Over longer time scales, the degenerate objects evolve and sublimate through the decay of their constituent nucleons. When the white dwarfs and neutron stars disappear, black holes are the brightest astrophysical objects, slowly losing their mass as they emit Hawking radiation. After the largest black holes have evaporated, the universe slowly slides into darkness.

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09:04
 
09:04
 
09:04

The Dark Matter & Dark Energy [1/5]

Dark matter are invisible objects that react with matter by gravitational force. Scientists believe that the dark matter is made up of exotic particles like WIMPs(Weakly Interacting Massive Particles).In physical cosmology, dark energy is an exotic form of energy that permeates all of space and tends to increase the rate of expansion of the universe.Dark energy is the most popular way to explain recent observations that the universe appears to be expanding at an accelerating rate. In the standard model of cosmology, dark energy currently accounts for 73% of the total mass-energy of the universe.

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08:59
 
08:59
 
08:59

The Dark Matter & Dark Energy [2/5]

Dark matter are invisible objects that react with matter by gravitational force. Scientists believe that the dark matter is made up of exotic particles like WIMPs(Weakly Interacting Massive Particles).In physical cosmology, dark energy is an exotic form of energy that permeates all of space and tends to increase the rate of expansion of the universe.Dark energy is the most popular way to explain recent observations that the universe appears to be expanding at an accelerating rate. In the standard model of cosmology, dark energy currently accounts for 73% of the total mass-energy of the universe.

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09:13
 
09:13
 
09:13

The Dark Matter & Dark Energy [3/5]

Dark matter are invisible objects that react with matter by gravitational force. Scientists believe that the dark matter is made up of exotic particles like WIMPs(Weakly Interacting Massive Particles).In physical cosmology, dark energy is an exotic form of energy that permeates all of space and tends to increase the rate of expansion of the universe.Dark energy is the most popular way to explain recent observations that the universe appears to be expanding at an accelerating rate. In the standard model of cosmology, dark energy currently accounts for 73% of the total mass-energy of the universe.

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Views: 319 | Comments: 0