determining the origins of the universe. learning goals students will: 1) understand the theories...

Determining the origins of the Universe

Learning Goals Students will: 1) Understand the theories for the formation of the universe.

Success Criteria Students will show their understanding of learning goals by: 1) Listing the evidence for the Big Bang theory

Introduction http://www.youtube.com/watch?v=zDQzKTedGN E (Nice 4 minute preview) http://www.youtube.com/watch?v=zDQzKTedGN E http://www.youtube.com/watch?v=PV0ACIykxQI (Big Bang Part 1 Nat Geo) http://www.youtube.com/watch?v=PV0ACIykxQI http://www.youtube.com/watch?v=phV-Zpy1BeM (Big bang Part 2 Nat Geo) http://www.youtube.com/watch?v=phV-Zpy1BeM http://www.youtube.com/watch?v=fK375XB3v08 (Big bang Part 3 Nat Geo) http://www.youtube.com/watch?v=fK375XB3v08 http://www.youtube.com/watch?v=gr8zLAxPs-A (Big Bang Part 4 Nat Geo) http://www.youtube.com/watch?v=gr8zLAxPs-A

Remember Spectroscopy! In the 1800s, astronomers began to experiment with tools called spectroscopes (or spectrographs). A spectroscope is a device that divides light into a spectrum of its component wavelengths. Spectrographs are produced by a spectrometer Instead of using a prism, many spectrometers break up light into a spectrum using a diffraction grating some of these are supplied in the classroom.

Spectra 1)White light produces a complete or continuous spectrum 2)A heated gas will produce a line spectrum or emission spectrum each gas has its own pattern of lines (many lines are invisible because they are seen in the IR and UV wavelengths) 3)A cool gas interfering with white light will produce an absorption spectrum. Certain wavelengths of light are removed from a continuous spectrum

Spectrographs Scientists in the 1800s made the discovery that light produced by a glowing gas did not produce a full spectrum, but just a few lines from the light spectrum Spectroscopes showed that the light from a specific material, such as a glowing tube of hydrogen, always produced the same distribution of wavelengths unique to that material. Use the spectroscopes supplied in the class to look at various gases. Try looking at the suns spectra or the spectra from a fluorescent light. Hydrogen Helium Carbon

The value of spectra to astronomers It became clear that by looking at the wavelength distribution from a spectrograph, you could figure out what kind of elements were in a light source. Hence you could determine the chemical composition of a star from its emission spectra. Typically stars are composed mostly of Hydrogen and Helium. The sun consists of 71% H, 27% He, 1% O and the last percent is made of C, N, Si, Mg, Ne, Fe and S. Similarly, the light reflected from a planet such as Jupiter or Venus would produce an absorption spectra Stars are actually classified by their spectra. Different spectra are indicators of different temperatures of stars and ages of stars. Young stars are hotter and have more hydrogen vs. helium

Modern Spectroscopy Instead of measuring the thickness or intensity of lines from a line spectrum, Modern Spectroscopy simply uses computers which produce a graph of intensity vs. wavelength.

YOU tube lectures on spectroscopy in astronomy This is a 3-part series. You might find that you want to skip to parts 2 and 3. http://www.youtube.com/watch?v=sVev5RsKXog http://www.youtube.com/watch?v=lsxvnVPLR1A &feature=relmfu http://www.youtube.com/watch?v=lsxvnVPLR1A &feature=relmfu http://www.youtube.com/watch?v=Bx0SMevn- 0c&feature=relmfu http://www.youtube.com/watch?v=Bx0SMevn- 0c&feature=relmfu

The Doppler Effect Physicist Christian Doppler discovered that the frequency of a sound wave depended upon the relative position of the source of the sound. As a noisy object approaches you, the sound waves it generates compress. This changes the frequency of the sound, and so you perceive the sound as a different pitch. When the object moves away from you, the sound waves stretch and the pitch goes down. It's called the Doppler Effect.

The Red Shift Astronomers in the early 1900s discovered that the lines of many stars were shifted right towards the red side of the spectrum. The explanation for this can be made by comparing the red shift of light to the Doppler effect on sound waves.

The movement of stars The conclusion is that we can tell if stars are moving towards or away from the Earth. Notice the position of the spectral lines have been shifted from the normal rest position

Steady State Theory Big Bang Theory

The Steady State Theory An unchanging Universe In the early 20 th century, the prevailing theory for the Universe was that the universe had existed pretty much in its present form for eternity with little change! The Steady State Theory suggests that there was no beginning, nor will there be an end to the universe. It believes that new stars and galaxies form to fill any empty space that has been left behind by old stars and galaxies moving away from each other.

The Steady State Theory:Einstein & the Cosmological Constant The first challenge to the Steady State Theory came from Albert Einstein who had recently published the Theory of General Relativity (1915). Einstein recognized that gravity should start to draw stars and other matter together, causing the universe to slowly collapse in on itself. Einstein, a believer of the Steady State Theory at the time, dealt with problem by adding the Cosmological Constant (1917) to his mathematical equations to hold gravity back. This constant allowed the universe to remain constant but would later become in Einsteins own opinion, his greatest mistake.

The Steady State Theory A Modern Version The modern Steady State theory was established in 1949 by Fred Hoyle, Hermann Bondi and Tommy Gold. Theoretical calculations showed that a static universe was impossible under general relativity, and observations by Edwin Hubble had shown that the universe was expanding. The Modern Steady State Theory asserts that although the universe is expanding, it nevertheless does not change its appearance over time (the perfect cosmological principle); the universe has no beginning and no end.

The Steady State Theory A Modern Version Hoyle suggested that an expanding universe that stays in perfect balance like a pool kept full to overflowing by a trickle from a faucet. The "faucet" of the universe would be the continuous creation of matter from energy. In other words as the universe expands new galaxies and stars are added to fill voids and the galaxy has the appearance of never changing. Though Hoyles theory would be proven wrong, he predicted that the source of all heavy elements in the universe were the result of fusion reactions within stars.

The Discovery made by Edwin Hubble Edwin Powell Hubble (November 20, 1889 September 28, 1953) was an American astronomer who did his best work at the Hooker Telescope (a 110 inch (2.5 m) telescope the worlds largest at that time) located on Mt. Wilson in southern California. Hubble was actually a high school teacher and school basketball coach who later went back to school to obtain his Ph.D. in Astrophysics. A major breakthrough in our understanding of the universe took place in the 1920's thanks to Hubble. For centuries, astronomers believed that the Milky Way made up the entire universe. Hubble was among the first to show that the fuzzy patches in the sky seen through telescopes were other galaxies, not distant parts of the Milky Way.

The Discovery made by Edwin Hubble Hubble conducted a study of stars and their spectra. He analyzed the red shifts of stars and more importantly galaxies and determined the distances to stars using the Hubble constant. Hubble made the amazing conclusion that all galaxies were moving away from each other AND that the further the distance of a star or galaxy, the greater its red shift (and therefore velocity).

Hubbles discovery The bottom spectrum is the absorption spectrum of the sun, and those above it for galaxies progressively further away. The pattern of absorption lines shifts further and further to the right, toward the red end of the spectrum. What does this mean?

The Universe is Expanding In the 1920s, Edwin Hubble noticed something interesting. The velocity of a star appeared to be proportional to its distance from the Earth. In other words, the further away a star was from Earth, the faster it appeared to move away from us. Hubble theorized that this meant the universe itself was expanding !

Hubbles Law The discovery of the linear relationship between red shift and distance, yields a straightforward mathematical expression for Hubble's Law as follows: Where v = H 0 D v is the recessional velocity, typically expressed in km/s. H 0 is Hubble's constant D is the proper distance measured in megaparsecs (Mpc) Hubble's Law is considered a fundamental relation between recessional velocity and distance

The Universe is Expanding Since light coming from more distant stars and galaxies takes longer to arrive than from nearer stars; it means that the farther into space we look, the farther back into time we are looking In other words, looking deeper into space means we are looking further back into time.

The Universe appears to be expanding from a central location in the universe. The Universe is Expanding Working backwards using this rate of expansion, we can estimate the age of the universe. This means we are effectively looking back in time, looking at light that was emitted in the early days of the universe. Since the universe appears to be expanding from a central location we can hypothesize that if we move back far enough in time we can deduce that the entire universe expanded from a single point!

The Universe is Expanding The fact that we see all other galaxies moving away from us does not imply that we are the center of the universe! All galaxies will see all other stars moving away from them in an expanding universe. A rising loaf of raisin bread is a good visual model: each raisin will see all other raisins moving away from it as the loaf expands.

The Big Bang Theory In the early 20th century, Georges Lematre was the first scientist to suggest that the universe expanded from a single point. Later work by mathematicians and astrophysicists such as Einstein, Freidman and Hubble provided support for the theory. Russian scientist, George Gamow, one of Friedman's pupils, was the major advocate of the Big Bang theory. Gamov defected from the USSR in 1933 and did most of his work in astronomy in the USA Gamov suggested suggested that the universe must have exploded from an extremely dense, hot state. In 1950, British astronomer Fred Hoyle, who co-founded the opposing steady-state theory, ridiculed Gamows theory with the term the big bang, but the name stuck.

Cosmic Microwave Radiation: P roof of the Big Bang? Together with colleagues Ralph Alpher & Robert Herman, Gamov predicted the cosmic microwave background (CMB) radiation, which is a radiation that should exist throughout the universe as a remnant of the Big Bang. In the 1960s, two researchers Arno Penzias and Robert Wilson, tried to eliminate the noise background picked up by microwave antennae. Unable to get rid of a mysterious background signal that remained constant in any direction, at any time, they phoned Princeton University, reaching the team that was looking for this very type of radiation. It turns out that this background noise or static was actually the Cosmic Microwave Background radiation. Stephen Hawking stated that this was the final nail in the coffin for the Steady State Theory. A map of the cosmic microwave background radiation note that it is uneven.

The CMB What Is It? What Does It Tell Us? The Cosmic Microwave Background (or "CMB" for short) is radiation from around 300,000 years after the start of the Universe. A blink of an eye when compared to the age of the Universe, which is around 13.82 billion (13,820,000,000) years old. Before this time, the Universe was so hot and dense that it was opaque to all radiation. Not even simple atoms could form without instantly being ripped apart into their constituent protons and electrons by the intense radiation. Thus the Universe was made of a "plasma", or ionized gas, which is what the surface of the Sun is made of.

The CMB: radiation remnant of the big bang! Ever since the Big Bang, the Universe has been cooling and expanding. By around 300,000 years through its life it was cool enough (though still around 3000 Celsius) for the simplest atoms to form, and it became transparent. The light from this time has been travelling through space ever since, and can be detected all around us from here on Earth or in space. We can measure the afterglow of the Big Bang. The expansion of the Universe has stretched out the CMB radiation by around 1000 times, which makes it look much cooler. So instead of seeing the afterglow at 3000 degrees, we see it at just 3 K

The CMB is Not Uniform! At present, cosmologists are very interested in small variations in the cosmic microwave background and these are proving a rich source of information. The Planck mission, using a satellite launched on 14th May 2009, aims to measure these variations more accurately than has been achieved before. This may yield vital clues as to the distribution of dark energy and other open questions. The Planck Satellite superimposed over an image of the Cosmic Microwave Background.

Looking for Evidence for the Big Bang Lematre said that this event would have left behind some signature radiation. Some time later, scientists began to look for corroboration of this model, theorizing that light from the beginning of the universe would be red-shifted to microwave wavelengths (a wavelength of EMR that is much smaller than light). Astronomers also began looking for the most distant objects in the universe knowing that they would have been created soon after the Big Bang.

Evidence for the Big Bang http://www.youtube.com/watch?v=uyCkADm NdNo (Good Video with a summary of Big bang evidence this is actually part of an atheism vs. creationism argument) http://www.youtube.com/watch?v=uyCkADm NdNo

Evidence for the Big Bang 1) Hubbles Work - the universe is expanding based on the red shift of stars and galaxies (1920s) 2) The CMB the left over radiation of the Big Bang predicted by Gamov was discovered by Penzias and Wilson (1964). 3) Gamow used the new science of Quantum mechanics (1930s) to predict that the forces of the Big Bang and nuclear fusion within stars would create an abundance of H and He in the stars of 75% H and 25% He this is what we observe from interstellar gases.

Evidence for the Big Bang 4) Gamow also calculated (using the limited technology of the 1930s and 1940s) that the heat/radiation left over from the Big bang would leave a background temperature in the universe of 5K (kelvin) his calculation was close recent studies of the CMB give a value closer to 3K. 5) Studies by the Hubble Space telescope show that the most distant galaxies have very immature structures (elliptical) in comparison with those closer to Earth (spirals). This suggests that these galaxies are younger and in their earlier stages of formation. This is also backed by the fact that most Quasars (which turn into galaxies) tend to be found only in the most distant reaches of space.

Evidence for the Big Bang 6) Studies of white dwarf stars (the remnants (cores) of burned out stars show that the oldest white dwarves are about 13.8 billion years old in line with the estimates given for the Big Bang. As evidence mounts for the Big Bang, this theory becomes stronger. At present, much work is being done with atomic supercolliders (cyclotrons) to determine he forces present in the earliest instants of the universe. Data and mathematical predictions give the following predictions for the conditions found in the Universe just after the Big Bang.

The Formation of the Universe Starting with the Big Bang Today, when we look at the night sky, we see galaxies separated by what appears to be huge expanses of empty space. At the earliest moments of the big bang, all of the matter, energy and space we could observe was compressed to an area of zero volume and infinite density. Cosmologists call this a singularity. (In fact matter can be created from energy E = mc 2 ) What was the universe like at the beginning of the big bang? According to the theory, it was extremely dense and extremely hot. There was so much energy in the universe during those first few moments that matter as we know it couldn't form. But the universe expanded rapidly, which means it became less dense and cooled down. As it expanded, matter began to form and radiation began to lose energy. In only a few seconds, the universe expanded out of a singularity and began to stretched.

Big bang timeline

The GUT (Grand Unified Theory) Era:10 -43 seconds The universe begins with a cataclysm that generates space and time, as well as all the matter and energy the universe will ever hold. For an incomprehensibly small fraction of a second, the universe is an infinitely dense, hot fireball. The prevailing theory describes a peculiar form of energy that can suddenly push out the fabric of space. All known forces are combined into a single force gravity, electromagnetism, the strong nuclear force, the weak nuclear force the grand unified force.

The inflation Era: 10 -38 to 10 -3 seconds At 10 -38 to 10 -33 seconds a runaway process called " Inflation " causes a vast expansion of space filled with this energy. The inflationary period is stopped only when this energy is transformed into matter and energy as we know it. The most basic forces in nature become distinct: first gravity, then the strong force, which holds nuclei of atoms together, followed by the weak and electromagnetic forces. Elementary particles form (quarks, electrons, neutrinos) (These particles will eventually combine to form protons and neutrons) At this point there is an almost equal amount of matter and anti-matter. These two types of matter begin to annihilate each other but a small excess of matter remains.

The Era of nucleosynthesis: 10 -3 seconds Elementary particles smash together in this high energy environment to form the first atomic nuclei mostly hydrogen and helium The universe is still too hot for the nuclei to capture electrons. (Matter is plasma - hot ionic gas) It will take another 300,000 years for electrons to be captured into orbits around these nuclei to form stable atoms. The ratio of nuclei is 75% H and 25% He one millionth of a second after the Big Bang, the universe continues to expand but not nearly so quickly. As it expands, it becomes less dense and cools.

The radiation era: 3 seconds to 300000 years The first major era in the history of the universe is one in which most of the energy is in the form of EM radiation. This energy is the remnant of the primordial fireball, and as the universe expands, the waves of radiation are stretched and diluted until today, they make up the faint glow of microwaves which bathe the entire universe. Matter continues to form for the next 300,000 years and eventually matter will dominate over radiation.

Beginning the Era of Matter Domination: 300,000 years At this moment, the energy in matter and the energy in radiation are equal. But as the relentless expansion continues, the waves of light are stretched to lower and lower energy, while the matter travels onward largely unaffected. At about this time, neutral atoms are formed as electrons link up with hydrogen and helium nuclei. The microwave background radiation hails from this moment, and thus gives us a direct picture of how matter was distributed at this early time.

Era of Galaxies: 300 million years Gravity pulls matter together and the first stars and galaxies are formed Gravity amplifies slight irregularities in the density of the primordial gas. Even as the universe continues to expand rapidly, pockets of gas become more and more dense. Stars ignite within these pockets, and groups of stars become the earliest galaxies. This point is still perhaps over 13 billion years before the present.

Video review http://www.youtube.com/watch?v=xsQ1XmqEe6 M (Astronomy Magazine Big Bang) http://www.youtube.com/watch?v=xsQ1XmqEe6 M http://www.youtube.com/watch?v=mvBFY_FtGfY &feature=relmfu (The Evidence for the Big Bang in 10 Little Minutes) Great Video SHOW THIS!!!!!!!! http://www.youtube.com/watch?v=mvBFY_FtGfY &feature=relmfu http://www.youtube.com/watch?v=ttpkto9Cm5c& feature=relmfu (Dark Matter) http://www.youtube.com/watch?v=ttpkto9Cm5c& feature=relmfu

The Four Basic Forces come into Being! One result of the big bang was the formation of the four basic forces in the universe. These forces are: Electromagnetism Strong nuclear force Weak nuclear force Gravity At the beginning of the big bang, these forces were all part of a unified force. It was only shortly after the big bang began that the forces separated into what they are today. How these forces were once part of a unified whole is a mystery to scientists. Many physicists and cosmologists are still working on forming the Grand Unified Theory, which would explain how the four forces were once united and how they relate to one another.

The Grand Unified Theory (GUT) The latest attempt to produce a GUT Grand Unified Theory a theory to unify all forces into a single force is called String Theory for help with this see Mr. Teahen! Two great places to read about String Theory are: 1)The NOVA (PBS) series hosted by Brian Greene http://www.pbs.org/wgbh/nova/elegant/ The Official String Theory Website http://superstringtheory.com/ The LHC (Large Hadron Collider at CERN hopes to shed some light on the Grand Unified Theory Yes, Physics is the means by which we will solve the mysteries of the Universe. for help with this see Mr. Teahen!

determining the origins of the universe. learning goals students will: 1) understand the theories...

Documents

light spectrum spectroscopes

white light

helium slide

e http

nat geo http

line spectrum

continuous spectrum

emission spectrum