1 / 13

Cosmology

Cosmology. The Study of the Origins of the Universe. Two Conflicting Theories. The Big Bang Theory said that all of the matter in the universe came from a a small dense sphere which exploded outward in all directions at some point in the past.

lois-gaines
Download Presentation

Cosmology

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Cosmology The Study of the Origins of the Universe

  2. Two Conflicting Theories • The Big Bang Theory said that all of the matter in the universe came from a a small dense sphere which exploded outward in all directions at some point in the past. • The Steady State Theory said that the universe is constant, with no beginning or end, with new matter being generated between galaxies. • Which was right?

  3. Big Bang Beginnings • Einstein - applications of his theory of General Relativity indicate a changing universe, not a stationary one • However, the unchanging universe was universally accepted at the time, so Einstein looked for a way to “tweak” his theory to make it fit. • This is a bad idea. You should never change the theory to fit your own opinion. • LeMaitre – His theory of a primordial atom that exploded to form the universe as we know it was dismissed by Einstein. • Another bad idea for Einstein. He should have believed his own theory. Einstein’s model video

  4. Redshift • Objects moving towards us have their wavelengths compressed. (demo) • For light this means they are shifted towards the blue end of the spectrum • Objects moving away from us have their wavelengths stretched. For light they will shift towards the red end of the spectrum. Notice the sodium spectrum here. Which shows an object moving towards us? Away from us? Which is moving away fastest?

  5. Edwin Hubble • Hubble’s observations of other galaxies and their redshifts showed that the universe is expanding. Video link • Put this together with Einstein’s theory and VOILA! Theory and observation fit to make a great theory – Big Bang video

  6. Raisin Bread Analogy The raisins represent the galaxies. As bread rises, raisins move apart. In the same way as the universe expands, galaxies move apart.

  7. The skeptic • Hoyle – believed strongly in the Steady State Theory. He sarcastically called the other theory the “Big Bang.” That’s where the name came from. • Hoyle also said that if the Big Bang was true, there should be remnant radiation left over from the initial explosion, but cooled and stretched to long wavelengths. video link

  8. Nobel Prize time • Dicke and Wilkinson - Robert Dicke of Princeton decided to look for this remnant radiation. He had an idea of how to look for it and asked his colleague David Wilkinson to work on it. • Penzias and Wilson - Luck steps in. Arno Penzias and Bob Wilson, working at Bell Labs are trying to get rid of a hiss in radio communications. They can not figure out where this microwave radiation is coming from. They try everything they can think of. Finally a friend tells them to call Robert Dicke at Princeton. • Penzias and Wilson have found the radiation that Dicke and Wilkinson just started to look for. They win a Nobel prize for this evidence of the Big Bang. • (Video later)

  9. Image of Big Bang • Shown are • The Big Bang • Inflation • The 1st Light (explain) • The time is a little off though as we will see in the next video

  10. Better pictures • COBE – The early information showed only overall radiation. COBE was sent up to get a better image of the variations in the background radiation, which would tie in to structures in the early universe which created galaxies, etc. • WMAP – Newest satellite (originally called MAP, changed to WMAP in honor of Wilkinson who had done a lot of the research and died in 2002.) This more detailed data was so good that it enabled astronomers to accurately date the age of the universe at 13.7 billion years. 2nd movie link

  11. The Future? • There are 3 possible fates of the universe according to the Big Bang Theory. The fate depends on how much matter the universe contains. • If there is a lot, then gravity will take over and the universe will contract again. This is a closed universe. • If the critical density = 1 then the universe is flat and will stop expanding but not contract • If, however, the critical density is too low, the universe will expand forever. This is an open universe. • The amount of matter depends on how much “dark matter” there is. • All three theories assume that the speed of the universe is slowing. However …. Strangely enough, recent evidence seems to indicate that the rate of expansion of the universe has actually sped up. This has led to a new idea called dark energy which counteracts gravity. Perhaps Einstein’s cosmological constant fudge factor has merit after all. So what will the future bring?

  12. Correcting for acceleration If the expansion is actually speeding up, we need a new curve here. Using SmartBoard tools, can we sketch it in here?

  13. Hubble Activity • We will soon do a lab which shows how Hubble’s data showed an expanding universe and will calculate an age of the universe from the data. Before we do, let’s talk about how we might figure out the age of the universe. • Video link • Hubble Lab and data page and Excel page • If you want to do this at home, you can also download this software free, at the CLEA website.

More Related