COSMOLOGICAL PRINCIPLE

Transcription

1 THE BIG BANG

2 COSMOLOGICAL PRINCIPLE According to cosmological principle, the universe is homogeneous and isotropic (Looks same in all directions) When you look up at night, your line of sight must eventually encounter a star. Olbers s Paradox If homogeneous and isotropic entire night sky should be as bright as the sun.

3 COSMOLOGICAL PRINCIPLE Then, if not, which it is homogeneous and isotropic (the light hasn t got here, yet), or it is not homogeneous and isotropic, you must assume that one or both of the following statements is wrong or false. The universe is infinite in extent, because the light hasn t gotten here yet or It is unchanging in time.

4 COSMOLOGICAL PRINCIPLE So, because the sky is still dark at night or the night sky is still black, then: The universe must be either finite, or Evolves over time, or both.

5 FUZZY OBJECTS In the mid 1750 s, a Frenchman named Charles Messier started observing fuzzy patches in the night sky that he thought where comets. They where not. They turned out to be what he called nebula. A nebula is a general term used for any fuzzy patch on the sky, either light or dark. He named them M 1, M 2, M 54, M 105, ect. Edmund Hubble started looking at these nebula and saw galaxies.

6 AN OBSERVED REDSHIFT There was already observational evidence in support of an expanding universe. In 1912, American astronomer Vesto Slipher observed a spiral galaxy (considered a "spiral nebula" at the time, since astronomers didn't yet know that there were galaxies beyond the Milky Way) and recorded its redshift. He observed that all such nebula were traveling away from the Earth. The problem was that these results were quite controversial at the time and the full implications of them were not considered.

7 EARLY EXPANDING UNIVERSE FINDINGS In 1922, Russian cosmologist & mathematician Alexander Friedman found that solutions to Einstein's general relativity field equations resulted in an expanding universe. As a believer in a static, eternal universe, Einstein added a cosmological constant to his equations, "correcting" for this "error" and thus eliminating the expansion. He would later call this the biggest blunder of his life".

8 GALAXIES In 1924, astronomer Edwin Hubble was able to measure the distance to these "nebula" and discovered that they were so far away that they were not actually part of the Milky Way... He had discovered that the Milky Way was only one of many galaxies, and that these "nebulae" were actually galaxies in their own right.

9 GEORGES LEMAITRE In 1927, Roman Catholic priest and physicist Georges Lemaitre independently calculated the Friedman solution and again suggested that the universe must be expanding. This theory was supported by Hubble when, in 1929, he found that there was a correlation between the distance of the galaxies and the amount of redshift in that galaxy's light. The distant galaxies were moving away faster, which was exactly what was predicted by Lemaitre's solutions.

10 GALAXIES PICTURES In 1929, Edmund Hubble developed Hubble s Law and took pictures of galaxies, measuring the speeds of each. Knowing speed, in the equation of speed, speed = distance/time, and solving for time, so, time = distance/speed, you can bring all galaxies back to a single point.

11 GEORGES LEMAITRE In 1931, Lemaitre went further with his predictions, extrapolating backwards in time, he finds that the matter of the universe would reach an infinite density and temperature at a finite time in the past. This means the universe must have begun in an incredibly small, dense point of matter - a "primeval atom."

12 PHILOSOPHICAL SIDE NOTE The fact that Lemaitre was a Roman Catholic priest concerned some, as he was putting forth a theory which presented a definite moment of "creation" to the universe. In the 20's & 30's, most physicists - like Einstein - were inclined to believe that the universe had indeed always existed. That it was steady. In essence, the Big Bang theory was seen as "too religious" by many people.

13 AGE OF THE UNIVERSE Since Hubble s constant is not precise the best guess is the universe is between 10 and 20 billion years old. Most astronomers predict between 10 and 14 billion years. Most Astronomers believe the universe came from a gigantic explosion of pure energy.

14 AGE OF THE UNIVERSE The big bang represented the beginning of the entire universe mass, energy, space, and time came into being at that instant. Theorists estimate the known Physics of today is adequate to describe the universe since 1 X seconds after the Big Bang. Close enough to the original time, until the summer of 2012.

15 SIR FRED HOYLE The term, the Big Bang, was coined by the English astrophysicist Fred Hoyle in Hoyle, who championed a rival cosmological theory, despite popularising the theory by giving it a name, challenged the belief that the cosmos was caused by a huge explosion 12,000 million years ago. He advocated the "steady state" theory - that the cosmos had no beginning but new galaxies were formed as others moved apart. Hoyle meant the "Big Bang" to be a term of derision, but the name was so catchy that it stuck.

16 CONCERNS REMAINED One of these was the problem of homogeneity. Why does the universe look identical, in terms of energy, regardless of which direction one looks? The Big Bang theory does not give the early universe time to reach thermal equilibrium, so there should be differences in energy throughout the universe.

17 COSMIC MICROWAVE BACKGROUND RADIATION The accidental discovery of cosmic microwave background radiation is a major development in modern physical cosmology. Although predicted by earlier theories, it was first found accidentally by Arno Penzias and Robert Woodrow Wilson as they experimented with the Holmdel Horn Antenna.

18 COSMIC MICROWAVE BACKGROUND RADIATION After thoroughly checking their equipment, removing some pigeons nesting in the antenna and cleaning out the accumulated droppings, the noise remained. Both concluded that this noise was coming from outside our own galaxy although they were not aware of any radio source that would account for it.

19 COSMIC MICROWAVE BACKGROUND RADIATION At that same time, Robert H. Dicke, Jim Peebles, and David Wilkinson, astrophysicists at Princeton University just 37 miles away, were preparing to search for microwave radiation in this region of the spectrum. Dicke and his colleagues reasoned that the Big Bang must have scattered not only the matter that condensed into galaxies but also must have released a tremendous blast of radiation. With the proper instrumentation, this radiation should be detectable.

20 COSMIC MICROWAVE BACKGROUND RADIATION When a friend told Penzias about a preprint paper he had seen by Jim Peebles on the possibility of finding radiation left over from an explosion that filled the universe at the beginning of its existence, Penzias and Wilson began to realize the significance of their discovery. The characteristics of the radiation detected by Penzias and Wilson fit exactly the radiation predicted by Robert H. Dicke and his colleagues at Princeton University.

21 COSMIC MICROWAVE BACKGROUND RADIATION The discovery was evidence for an expanding universe, (Big Bang Theory) and was evidence against the steady state model. In 1978, Penzias and Wilson were awarded the Nobel Prize for Physics for their joint discovery.

22 STEPHEN HAWKING SINGULARITY THEORY The work of Stephen Hawking proposed that the universe acted like an exploding star, a supernova. A singularity in solutions of the Einstein field equations is one of two things: a. a situation where matter is forced to be compressed to a point (a space-like singularity) b. a situation where certain light rays come from a region with infinite curvature (time-like singularity)

23 STEPHEN HAWKING SINGULARITY THEORY Hawking and his Cambridge friend and colleague, Roger Penrose, showed in 1970 that if the universe obeys general relativity and fits any of the Friedmann models, then it must have begun as a singularity. Remember, Friedmann was the Russian scientisits who used Einstein s equations to predict an explanding universe.

24 HEAT SIGNATURE Evidence collected by the COBE satellite between 1990 to 1992, showed that the universe was not an even temperature, but has hot spots that eventually became the galaxies. The cosmic microwave background radiation is a remnant of the Big Bang and the fluctuations are the imprint of density contrast in the early universe.

25 EXISTING CONTROVERSIES While the Big Bang theory is accepted by the vast majority of physicists, there are still some minor questions concerning it. Most importantly, however, are the questions which the theory cannot even attempt to answer.

26 EXISTING CONTROVERSIES What existed before the Big Bang? What caused the Big Bang? Is our universe the only one? The answers to these questions may well exist in String Theory...\..\..\..\Videos\Michio Kaku Explains String Theory_(360p).avi

27 THE GOD PARTICLE The Higgs boson, Higgs particle, or the God particle, is a proposed elementary particle in the Standard Model of particle physics. The Higgs boson's existence would have profound importance in particle physics because it would prove the existence of the hypothetical Higgs field and the means by which elementary particles acquire mass...\..\..\..\videos\angels and Demons - The God Particle_(360p).avi

28 THE GOD PARTICLE The Higgs boson is named for Peter Higgs who, along with two other teams, proposed the mechanism that suggested such a particle in On 4 July 2012, the CMS and the ATLAS experimental teams at the Large Hadron Collider independently announced that they each confirmed the formal discovery of a previously unknown boson of mass between GeV/c 2.

29 THE GOD PARTICLE The particle s behavior so far has been "consistent with" a Higgs boson. Proof of the Higgs field (by observing the associated particle), and evidence of its properties, is likely to greatly affect human understanding of the universe.

30 THE GOD PARTICLE This announcement means that observations show the newly discovered boson could be a Higgs boson, and it is widely believed by scientists to be very likely a Higgs boson, but further study of this particle, now that its existence is proven, will still be required to place beyond doubt the question whether the particle is in fact confirmed as a Higgs boson...\..\..\..\videos\scientists confirm 'God Particle' exists_(360p).avi

31 BIG BANG THEORY - WHAT ABOUT GOD? Any discussion of the Big Bang theory would be incomplete without asking the question, what about God? This is because cosmogony (the study of the origin of the universe) is an area where science and theology meet. Creation was a supernatural event. That is, it took place outside of the natural realm.

32 BIG BANG THEORY - WHAT ABOUT GOD? This fact begs the question: is there anything else which exists outside of the natural realm? Specifically, is there a master Architect out there? We know that this universe had a beginning. Was God the "First Cause"?

33 MARK TWAIN There is something fascinating about science. One gets such a wholesale return of conjecture out of such a trifling investment of fact.