1 / 11

GTR Continued

GTR Continued. Sections 29.3 - 29.4. Reminders. Lab this week LAB B1- WA Wave Addition : due by 4 p.m. Friday CCR Extra Credit due Thursday , May 1 Examination #3 on Thursday: Addresses Chapters 8, 9, 11-13 only 26 multiple-choice questions 2 extra credit questions

glen
Download Presentation

GTR Continued

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. GTR Continued Sections 29.3 - 29.4

  2. Reminders • Lab this week LAB B1-WA Wave Addition: due by 4 p.m. Friday • CCR Extra Credit due Thursday, May 1 • Examination #3 on Thursday: • Addresses Chapters 8, 9, 11-13 only • 26 multiple-choice questions • 2 extra credit questions • 30 points possible (120% maximum) • Final: Monday, May 5, 7:50- 9:50 A.M.

  3. Einstein, GTR, and the Universe • Einstein’s equation of general relativity: • The equation required an expanding universe, so Einstein arbitrarily added a “cosmological” constant to avoid this conclusion… • Recall that galactic nebulas had yet to be discovered as galaxies, and neither had the expanding universe!

  4. Friedmann’s Universe 1 • Starts with total energy: • Makes 3 simplifying assumptions: • Universe is essentially empty (on a larger scale) • Universe is isotropic (no preferred direction) • Universe is homogeneous (no preferred point) • and gets:

  5. Friedmann’s Universe 2 • Inserting E=mc2 and taking into account GTR, the prior equation results in: • where k is the curvature of the universe: • If k < 0, then universe is closed and bounded (positively curved). • If k > 0, then the universe is open and unbounded (negatively curved). • If k = 0, then the universe is flat.

  6. Friedmann’s Universe • Solving this equation, Friedmann predicted that the universe had to be expanding if it were to exist. • Einstein added the “cosmological constant” to his own field equations because he could not believe in an expanding universe. Later Einstein remarked, “That was the greatest scientific blunder that I ever made.”

  7. Hubble’s Relationship 1 • Following in the footsteps of others, Hubble determines recessional velocities from Doppler shifts.

  8. Hubble’s Relationship 2 • Hubble determines distances to “nebulas” using a variety of means: • Study of variable stars whose periods are related to their intrinsic brightness • Angular diameters by type • Presence of brightest stars in a galaxy by type • Presence of globular star clusters • Presence of supernovas by type (I and II)

  9. Hubble’s Law for Galaxies • Hubble used Doppler shifts and distances to study galaxies. He found a linear relationship. v = HR

  10. Abbé Georges Lamaître • Introduces the “Big Bang” • Concludes that time since universal expansion began could be found from Hubble parameter. • v = HR; now d/v = t; • v/R = H and d/v = 1/H • The current value of H (21-23km/s/Mly) shows the age of the universe to around 13.8 billion years.

  11. Hubble’s Law is consistent with the expansion of the universe.

More Related