Lecture_22

Lecture_22 - Chapter 17 continued The Beginning of Time We saw that strong evidence for the big Bang theory is found in the discovery of the Cosmic

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Chapter 17 continued Chapter 17 continued The Beginning of Time The Beginning of Time We saw that strong evidence for the big Bang theory is found in the discovery of the Cosmic Microwave Background (CMB), the residual heat of the universe itself. It is a perfect thermal radiation spectrum with a temperature of 2.73 K. This is just what we would expect if the universe expanded by about 1000 since the Era of Atoms (about 380,000 years old). THE WMAP SATELLITE TOOK THIS ALL- SKY PICTURE OF THE ULTRA-SMOOTH MICROWAVE BACKGROUND. TEMPERATURE VARIES BY NO MORE THAN 0.0001 K FROM PLACE TO PLACE. What have we learned? • How do we observe the radiation left over from the Big Bang? • Telescopes that can detect microwaves allow us to observe the cosmic microwave background, radiation left over from the Big Bang. • Its spectrum matches the characteristics expected of the radiation released at the end of the era of nuclei, spectacularly confirming a key prediction of the Big Bang theory. Peak wavelength of about 1mm gives us the temperature From NASA’s Cosmic Background Explorer (COBE) satellite: the two lead scientists got the Nobel Prize. Protons and neutrons combined to make long-lasting helium nuclei when the universe was ~3 minutes old . Fusion stopped after that because the universe had already cooled. As the hot dense universe expanded and cooled it went through the temperature range the allows hydrogen to fuse to helium THE BIG BANG EXPLAINS THE ABUNDANCE OF HELIUM THE BIG BANG EXPLAINS THE ABUNDANCE OF HELIUM Protons outnumbered neutrons by 7 to 1 Big Bang theory prediction: 75% H, 25% He (by mass) Matches observations of nearly primordial gases
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Abundances of other light elements agree with Big Bang model having 4-5% normal matter – more evidence for WIMPS! Theory confronts observations – the Scientific Method at work. The Big Bang and Inflation The Big Bang and Inflation Our Goals for Learning • What aspects of the universe were originally unexplained by the Big Bang model? Mysteries Needing Explanation
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/20/2012 for the course ASTRO 3 taught by Professor Mclean during the Spring '11 term at UCLA.

Page1 / 6

Lecture_22 - Chapter 17 continued The Beginning of Time We saw that strong evidence for the big Bang theory is found in the discovery of the Cosmic

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online