Origins of the Universe. The Big Bang Theory Until 100 years ago, scientists believed nothing ever changed in outer space. . The Big Bang Theory = everything in the universe came from a single starting point, approximately 13.7 billion years ago.
The Big Bang Theory = everything in the universe came from a single starting point, approximately 13.7 billion years ago.
1. Evidence For The Big Bang Theory
Horton Hears a Who:
Part 1 http://www.youtube.com/watch?v=B0qZ4V53EV4
Part 2 http://www.youtube.com/watch?v=3BsiN8SxUMM&feature=mfu_in_order&list=UL
c) Once astronomers realized everything was moving away from everything else, they realized the universe might have originated from a single point.
As the ambulance approaches, the sound waves from its siren are compressed towards the observer. The intervals between waves diminish, which translates into an increase in frequency or pitch.
As the ambulance recedes, the sound waves are stretched relative to the observer, causing the siren\'s pitch to decrease. By the change in pitch of the siren, you can determine if the ambulance is coming nearer or speeding away.
If you could measure the rate of change of pitch, you could also estimate the ambulance\'s speed.
= a change in pitch of a sound made by an object moving toward or away from another object.
i) As an object approaches, the sound waves in front of the object become compressed. The waves increase in frequency, energy, and results in a higher pitch.
i) An object at rest sends sound waves evenly in all directions
c) A spectroscope analyzes the unique spectrum of a star, which astronomers can analyze to discover the direction and amount the light has shifted.
A red shift means the wavelength is getting longer, and the star is moving away from us.
Blue shift is the opposite; the star is getting closer.
WMAP Resolves the UniverseCredit: WMAP Science Team, NASA
This radiation was mapped by the COBE and WMAP explorations.
Explanation: Analyses of a new high-resolution map of microwave light emitted only 380,000 years after the Big Bang appear to define our universe more precisely than ever before. The eagerly awaited results announced last year from the orbiting WilkinsonMicrowave Anisotropy Probe resolve several long-standing disagreements in cosmology rooted in less precise data. Specifically, present analyses of above WMAP all-sky image indicate that the universe is 13.7 billion years old (accurate to 1 percent), composed of 73 percent dark energy, 23 percent colddark matter, and only 4 percent atoms, is currently expanding at the rate of 71 km/sec/Mpc (accurate to 5 percent), underwent episodes of rapid expansion called inflation, and will expand forever. Astronomers will likely research the foundations and implications of these results for years to come.
A static universe, also referred to as a "stationary" or "Einstein" universe, is a model in which space is neither expanding nor contracting. Albert Einstein proposed such a model as his preferred cosmology in 1917. He added a positive cosmological constant to his equations of general relativity to counteract the attractive effects of gravity on ordinary matter, which would otherwise cause the universe to either collapse or expand forever. This motivation evaporated after the discovery by Edwin Hubble that the universe is in fact not static, but expanding; in particular, Hubble discovered a relationship between redshift and distance, which forms the basis for the modern expansion paradigm. According to Gamow this led Einstein to declare this cosmological model, and especially the introduction of the cosmological constant, his "biggest blunder".
Even after Hubble\'s observations, Fritz Zwicky proposed that a static universe could still be viable if there was an alternative explanation of redshift due to a mechanism that would cause light to lose energy as it traveled through space, a concept that would come to be known as "tired light". However, subsequent cosmological observations have shown that this model is not a viable alternative either, leading nearly all astrophysicists to conclude that the static universe is not the correct model of our universe.
The Einstein universe is one of Friedmann\'s solutions to Einstein\'s field equation for dust with density ρ, cosmological constant ΛE, and radius of curvature RE. It is the only non-trivial static solution to Friedmann\'s equations.
Because the universe is now known to be expanding the Einstein universe is no longer regarded as a viable model for our universe. Moreover, it is unstable in the sense that any change in either the value of the cosmological constant, the matter density, or the spatial curvature will result in a universe that either expands and accelerates forever or re-collapses to a big crunch.
After observations indicated that the universe was expanding, most physicists of the twentieth century assumed the cosmological constant is zero. If so (absent some other form of dark energy), the expansion of the universe would be decelerating. However, with the discovery of the accelerating universe, a positive cosmological constant has been revived as a simple explanation for dark energy.
Other problems with the model
Aside from Hubble\'s law, the cosmic microwave background radiation is used as empirical evidence of the Big Bang model. A static universe model has to explain this radiation in some other way. Also there has to be some process of "recreation of Hydrogen" since if the universe was not created some finite time ago, as in the Big Bang model, the stars would otherwise all have run out of fuel (Hydrogen) by now.
One of the implications of the big-bang theory is that the universe will one day end, or at least any life in the universe will come to an end. If the universe is either open or flat, meaning that it expands forever, it will survive for an infinite period of time. But eventually all the material in all the generations of stars will be exhausted and the universe will grow cold and dark. In a closed universe, in which the expansion eventually stops and a contraction follows, the end is far from cold and dark—as the Big Crunch approaches, the universe grows hotter and brighter until it implodes into a singularity and gets crushed out of existence.
But is that what would really happen? Some scientists speculate that the Big Crunch would not signal the end. Perhaps another Big Bang would follow the Big Crunch, giving rise to a new universe of possibilities. The idea that Bangs follow Crunches in a never-ending cycle is known as an oscillating universe. Though no theory has been developed to explain how this could ever happen, it has a certain philosophical appeal to people who like the idea of a universe without end.
Fate of the Universe http://www.universetoday.com/37105/fate-of-the-universe/
by John Carl Villanueva on August 10, 2009
What is the ultimate fate of our universe? A Big Crunch? A Big Freeze? A Big Rip? or a Big Bounce? Measurements made by WMAP or the Wilkinson Microwave Anisotropy Probe favor a Big Freeze. But until a deeper understanding of dark energy is established, the other three still cannot be totally ignored.
Ever since scientists proved the Big Bang to be the most plausible cosmological theory, and since it only focused more on how it might have all began, their attention started to shift to how the Universe would end. Thus, all 4 theories mentioned above (Big Crunch, Big Freeze, etc.) are actually offshoots of the Big Bang.
The Big Crunch predicts that, after having expanded to its maximum size, the Universe will finally collapse into itself to form the greatest black hole ever.
On the opposite side of the coin, the Big Freeze foretells of a universe that will continue to stretch forever, distributing heat evenly in the process until none is left to be usable enough. Hence, it is also known as the Heat Death.
A more dramatic version of the Big Freeze is the Big Rip. In this scenario, the Universe’s rate of expansion will increase substantially so that everything in it, down to the smallest atom, will be ripped apart.
In a cyclic or oscillatory model of the Universe, there will be no end … for matter and energy, that is. But for us and the Universe that we know of, there will definitely be a conclusion. In an oscillatory model, the Big Bang and Big Crunch form a pair known as the Big Bounce. Essentially, such a universe would simply expand and contract (or bounce) forever.
For astronomers to determine what the ultimate fate of the Universe should be, they would need to know certain information. Its density is supposedly one of the most telling.
You see, if its density is found to be less than the critical density, then only a Big Freeze or a Big Rip would be possible. On the other hand, if it is greater than the said critical value, then a Big Crunch or Big Bounce would most likely ensue.
The most accurate measurements on the cosmic microwave background radiation (CMBR), which is also the most persuasive evidence of the Big Bang, shows a universe having a density virtually equal to the critical density. The measurements also exhibit the characteristics of a flat universe. Right now, it looks like all gathered data indicate that a Big Crunch or a Big Bounce is highly unlikely to occur.
To render finality to these findings however, scientists will need to know the exact behavior of dark energy. Is its strength increasing? Is it diminishing? Is it constant? Only by answering these will they know the ultimate fate of the Universe.
We’ve got a few articles that touch on the fate the universe here in Universe Today. Here are two of them:
No “Big Rip” in our Future: Chandra Provides Insights Into Dark EnergyEnd of the Universe
NASA also has some more:The Life and Death of StarsWhat is the Ultimate Fate of the Universe
i) ROYGBIV. The red end of the visible spectrum is lower energy, while the blue end of the spectrum is higher energy.
The discovery of Eris -- which is similar in size to Pluto -- caused scientists to reconsider the definition of a planet. It has a moon named Dysnomia.
Eris Discovery Images
= a cloud of icy bodies beyond our solar system.
These four panels show the location of the newly discovered planet-like object, dubbed "Sedna," which lies in the farthest reaches of our Solar System. Each panel, moving counterclockwise from the upper left, successively zooms out to place Sedna in context.
The first panel shows the orbits of the inner planets, including Earth, and the asteroid belt that lies between Mars and Jupiter.
In this second panel, Sedna is shown well outside the orbits of the outer planets and the more distant Kuiper Belt objects.
The Oort cloud is a spherical distribution of cold, icy bodies lying at the limits of the Sun\'s gravitational pull. Sedna\'s presence suggests that this Oort cloud is much closer than scientists believed. Image Credit: NASA/JPL-Caltech/R. Hurt (SSC-Caltech) Credit: NASA/Caltech
Sedna\'s full orbit is illustrated in the third panel along with the object\'s current location. Sedna is nearing its closest approach to the Sun; its 10,000-year orbit typically takes it to far greater distances.
The final panel zooms out much farther, showing that even this large elliptical orbit falls inside what was previously thought to be the inner edge of the Oort cloud.
Both distant regions are named for the astronomers who predicted their existence -- Gerard Kuiper and Jan Oort.
Eris, the Greek goddess of discord, is often credited with starting the Trojan War. Alone among the Olympians, she was excluded from the arranged marriage of Peleus and Thetis because of her troublemaking inclinations. But exclusion was no deterrent. She tossed the Apple of Discord into the party, a golden apple inscribed καλλίστῃ (kallistei) – "to the fairest" – provoking Hera, Athena and Aphrodite to begin quarreling about the appropriate recipient. Paris, Prince of Troy, was appointed judge. Each of the three goddesses immediately attempted to bribe him. Hera offered political power; Athena promised skill in battle; and Aphrodite tempted him with the most beautiful woman in the world: Helen, wife of Menelaus of Sparta. While Greek culture placed a greater emphasis on prowess and power (Athena and Hera\'s domain), Paris chose to award the apple to Aphrodite (= Venus), thereby dooming his city, which was destroyed in the war that ensued when the Spartans demanded the return of their queen.
Artist\'s impression of Eris and her moon Dysnomia by Thierry Lombry
Comets from both regions are generally named for the person who discovered them.
Haumea sits among the trans-Neptunian objects, a vast ring of distant cold and rocky bodies in the outer Solar System. At this moment it is roughly 50 times the Sun-Earth distance from the Sun, but at its closest the elliptical orbit of Haumea brings it 35 times the Sun-Earth distance from our star.
Haumea is the name of the goddess of childbirth and fertility in Hawaiian mythology. The name is particularly apt as the goddess Haumea also represents the element of stone and observations of Haumea hint that, unusually, the dwarf planet is almost entirely composed of rock with a crust of pure ice.
Hawaiian mythology says that the goddess Haumea\'s children sprang from different parts of her body. The dwarf planet Haumea has a similar history, as it is joined in its orbit by two satellites that are thought to have been created by impacts with it in the past. During these impacts, parts of Haumea\'s icy surface were blasted off. The debris from these impacts is then thought to have gone onto form the two moons.
q discuss the variation in day length over a year for different latitudes
= the time when the sun appears above the horizon, from sunrise to sunset
(Above) Pictures of the sun taken 1 hour apart. This and the following images were from a scientific expedition in Antarctica, at a base located approximately 75o South.
(Above)Although DdU is a little south of the Antarctic circle, the sun is always visible at noon, even at the darkest of the winter. The reason is because of the refraction of light on the low atmosphere layers: you can actually see it while it\'s somewhat below the horizon. This picture was taken on June 21st with 9 exposures set 11 minutes apart if I remember right. One hour of sunlight is all we get in winter. Enough to go for a walk, but little else. I created my animated HR bar starting from this picture.
Evidence That Shows The Earth Rotates About Its Axis And Revolves Around The Sun
The pendulum bob (above) weighed 28 kg and was brass-coated lead. It was suspended from a wire 67 meters long! This replica in the Pantheon in Paris has been permanently swinging since 1995.
These drawings show the pattern that emerged when the pendulum was set in motion.
(left) The blue arcs show the pendulum swing; the green lines show the pattern left in the sand. Each pass was 11° different from the previous pass.
2) The Earth isn\'t round. It bulges around the equator, just as you would expect if it rotated. This was known when Foucault made his pendulum.
The Coriolis Effect was largely a curiosity until World War I, when the Germans built a generation of long-range cannons and found that they could not hit anything if they aimed directly at it; they had to aim to the left. (If the target was exactly east or west of the gun\'s position, the gun would be aimed directly at it.)
If you understand this discussion, you should be able to convince yourself that a cannonball fired southward (toward the equator) from some point in the Northern Hemisphere will be deflected to its right (west).
Effects such as these that come about because we live on a rotating frame of reference are referred to as Coriolis effects.
The Motion Of Stars And Planets Are Caused By Rotation And Revolution Of The Earth
Left: Star rotation shown by a long exposure. The star in the middle is Polaris.
Above: A shooting star and a passing satellite caught by a long exposure photography.