1. Dark Matter By Joel Tome Period 3

2. What is Dark Matter? ►T►T►T►The mass in galaxies and galactic clusters inferred to exist: bbbby rotational properties of galaxies bbbbending of light aaaand other techniques bbbbut has not been confirmed to exist by observations at any electromagnetic wavelength ►O►O►O►Originally called missing mass

3. Dark Matter on a Molecular Level ► decoupled from the rest of the universe since before the time primordial nucleosynthesis began ► experienced large fluxuations in density distribution since early in the history of the universe

4. Properties ► forms large-scale clumping and other mass distributions in the universe ► controls overall mass distribution in the universe  without affecting the microwave background radiation  or any other observational constraints in the universe ► drew gas and other matter into the vicinity of peaks in its distribution over universe’s history ► Covers anywhere between 20-85% of the universe

5. Two Theories of Creation ► Hot Dark matter  of very lightweight particles, even lighter than electrons  may be composed of neutrinos  development of superclusters, and vast empty regions called voids  do not explain the smaller-scale structures

6. Cold Dark matter ► consists of heavy particles that formed in the earliest microseconds (10^-43 second after the big bang) ► strong, weak, and electromagnetic forces still unified  can explain the formation of both large-scale and small-scale structures in the universe

7. Fritz Zwicky (1898-1974) ► Swiss astrophysicist ► examined a cluster of galaxies in constellation Coma Berenices (Berenice's Hair) in 1933 ► Noticed high velocity of individual galaxies  Could have escaped from g attraction

8. Zwicky’s Conclusion ►A►A►A►Amount of matter actually present must be greater than was visible UUUUsed doppler shifts to confirm invisible material

9. Milky Way ► Research  Milky Way contain invisible matter ► Exerting gravitational influence ► Most from galactic halo (10 times D of visible galaxy)  Galactic Halo cannot be seen (dark matter)

10. Two theories on current Dark Matter ► Ordinary matter not yet detected (from large objects that give off little light) ► Brown Dwarf  Material composition of a star but… ► Contains too little mass to permit core to initiate thermonuclear fusion ► White Dwarf  Low mass may actually make up half of dark matter in universe ► Black Holes  Another massive compact halo object (MACHO)

11. Not Accepted because… ► There are too few MACHOs to account for all dark matter in the universe

12. Theory 2 ► Weak interaction but massive particles (WIMP) ► Could explain cold dark matter ► Hypothetical form of matter: nonbaryonic matter  Doesn’t contain protons/neurons

13. Impact ► Thought to play a crucial role in determining fate of universe ► Based on mass in the universe, will it continue to expand OR shrink under its own gravity

14. Video ► http://videos.howstuffworks.com/nasa/1356 2-chandra-dark-matter-video.htm http://videos.howstuffworks.com/nasa/1356 2-chandra-dark-matter-video.htm http://videos.howstuffworks.com/nasa/1356 2-chandra-dark-matter-video.htm

15. Works Cited ► Angelo, Joseph A., Jr. "dark matter." Science Online. Facts On File, Inc. Web. 15 Apr. 2011.. ► "Dark matter." Gale Encyclopedia of Science. Ed. K. Lee Lerner and Brenda Wilmoth Lerner. 4th ed. Detroit: Gale Group, 2008. Discovering Collection. Gale. Mid-Pacific Institute. 15 Apr. 2011. ► Hooper, Dan. "Dark matter." World Book Advanced. World Book, 2011. Web. 15 Apr. 2011. ► Kusky, Timothy. "dark matter." Science Online. Facts On File, Inc. Web. 15 Apr. 2011..