4. 240,000 mi It takes light just over one second to travel from the moon to the earth

11. The simplest atom is hydrogen. Its nucleus is a single proton. And one distant electron moves around it

12. . An atom is nearly entirely empty space. A scale model has the electron at the outside of Miller Park, the nucleus a marble at its center

13. proton electron

21. neutron neutrino

22. neutron neutrino

23. Fusion of hydrogen to helium 4 protons 4 electrons

24. Fusion of hydrogen to helium 4 protons 4 electrons

25. Fusion of hydrogen to helium 4 protons 4 electrons

26. Fusion of hydrogen to helium 4 protons 4 electrons

27. Fusion of hydrogen to helium 4 protons 4 electrons

28. Fusion of hydrogen to helium 4 protons 4 electrons

29. Fusion of hydrogen to helium 4 protons 4 electrons

30. Fusion of hydrogen to helium 4 protons 4 electrons

31. Fusion of hydrogen to helium 2 protons 2 neutrons 4 electrons

32. Fusion of hydrogen to helium 2 protons 2 neutrons 4 electrons

33. Fusion of hydrogen to helium 2 protons 2 neutrons 4 electrons

34. Fusion of hydrogen to helium 2 protons 2 neutrons 4 electrons

35. Fusion of hydrogen to helium 2 protons 2 neutrons 4 electrons

36. Fusion of hydrogen to helium 2 protons 2 neutrons 4 electrons

37. Fusion of hydrogen to helium (Helium nucleus)

38. Fusion of hydrogen to helium

79. Chandrasekhar at about the time he found that an upper limit on the mass of white dwarfs was set by the upper limit c on the speed at which electrons can travel.

80. Matter is supported against gravity by its pressure. Recall that the pressure of a collection of particles depends on their speed.

94. What is left behind?

95. Lev Landau

96. Neutron stars Immediately after the neutron was discovered in 1930, Landau suggested the possibility that the pressure in the cores of stars might push the electrons onto their protons to make a core entirely of neutrons. proton electron

97. Neutron stars Immediately after the neutron was discovered in 1930, Landau suggested the possibility that the pressure in the cores of stars might push the electrons onto their protons to make a core entirely of neutrons. protonelectron

98. Neutron stars Immediately after the neutron was discovered in 1930, Landau suggested the possibility that the pressure in the cores of stars might push the electrons onto their protons to make a core entirely of neutrons. neutron neutrino

99. . If all of the electrons of the Sun were pulled onto their nuclei to form neutrons, the Sun would shrink by nearly 100,000 times, from 700,000 km to about 10 km

100. .

101. .

102. .

103. .

104. “With all due humility, we propose...” Walter Baade Fritz Zwicky

105. that supernovae represent the transition from ordinary stars to neutron stars, which represent their final stage.” Walter Baade Fritz Zwicky

106. A neutron star is about 1/1000 that size

107. Neutron Stars Radius about 10 km Density over 1 billion tons per teaspoon Mass about 1.5 Msun A neutron star is a giant atomic nucleus, made almost entirely of neutrons, held together by gravity Flashes of light seen as pole passes our line of sight (like the light from a searchlight beam sweeping past you) Neutron stars seen in this way are called pulsars

108. Jocelyn Bell, at about the time she discovered the first neutron stars.

109. To get full screen, need this already open.

114. Neutron star spinning about 5 times /second Neutron star spinning 642 times /second

117. 300,000 km/s It’s not just a good idea. It’s the law. The speed of light, 300,000 km/s (or 186,000 mph), is really the speed of information. It is the maximum speed at which anything can travel, matter or energy or simply a wave of curvature of space itself. No change in one place can alter what happens somewhere else more quickly than this speed limit allows.

118. Because of the limit on the speed of information, a charge moving up and down creates a wave in the electric field that moves outward at the speed of information, 300,000 km/s.

119. Because of the limit on the speed of information, a charge moving up and down creates a wave in the electric field that moves outward at the speed of information, 300,000 km/s.

120. Because of the limit on the speed of information, a charge moving up and down creates a wave in the electric field that moves outward at the speed of information, 300,000 km/s.

121. Because of the limit on the speed of information, a charge moving up and down creates a wave in the electric field that moves outward at the speed of information, 300,000 km/s.

122. Because of the limit on the speed of information, a charge moving up and down creates a wave in the electric field that moves outward at the speed of information, 300,000 km/s.

123. This speed limit is the reason light exists When a charge moves, the information that it is at a new position travels outward at 300,000 km/s. electric field

124. After 1 second, the electric field has changed only within a distance 1 light-second from the charge. After one second

125. After 2 seconds, the electric field has changed within a distance 2 light-seconds from the charge.

126. After 3 seconds, the electric field has changed within a distance 3 light-seconds from the charge.

128. Escape velocity from Earth: 7 mi/second from Sun: 500 mi/second from neutron star: 60,000 mi/second

129. John Michell 1784 First published suggestion of existence of black stars “supposing light to be attracted by the same force in proportion to its vis inertiae, all light emitted from such a body would be made to return towards it, by its own proper gravity”

130. Pierre Simon Laplace 1799 “Proof of the theorem, that the attractive force of a heavenly body could be so large, that light could not flow out of it.”

131. Star has collapsed to a speck No Exit: Everything within a few miles of the speck is pulled by gravity into it.

132. This is a black hole – A region of empty space from which nothing can escape

135. Matter falling on a black hole from its companion in a binary system

136. Light from the binary system containing Cygnus X-1, a 7 Msun black hole

137. Diagram of the same system

138. Diagram of matter falling onto a giant black hole

139. Hubble space telescope photos looking very much like the giant black hole that we expected to see

140. Real black holes (not the Newtonian limit)

141. Prerequisite: A light cone – The history of a flash of light

142. ALLOWED FOR MASSIVE BODY ALLOWED FOR LIGHT NOT ALLOWED

143. Light cones tip inward as you approach a black hole.

149. Inside the event horizon, the cone is tipped so far that light rays emitted outward cannot get out. TIME DISTANCE FROM CENTER OF STAR

150. A black hole is a region of space from which nothing can escape to the outside The boundary of a black holes is called the event horizon because no events occurring beyond the horizon can be seen from the outside. After a star has collapsed to within a black hole, it continues to collapse to the size of a speck. BLACK HOLES

151. Best stellar black hole candidates

152. Stars orbiting a region at the center of the Milky Way, revealing a central black hole of mass.

153. Closeup

154. Ghez, A. M., Klein, B. L., Morris, M., and Becklin, E. E. ApJ, 509, 678 (1998) High Proper Motions in the Vicinity of Sgr A*: Unambiguous Evidence for a Massive Central Black Hole High Proper Motions in the Vicinity of Sgr A*: Unambiguous Evidence for a Massive Central Black Hole Andrea Ghez “These observations reveal stars moving at apparent speed as high as 12,000 km/sec (~4% the speed of light!) whose orbits imply the presence of 4 million of dark matter interior to a radius of about 6 light hours ”

155. Strong evidence for giant black holes in the centers of nearly all galaxies

156. Supermassive Black Holes in Galactic Centers

157. The geometry near a collapsing star This shows the geometry of a plane through the center of the star.

158. Geometry of a plane through the center of the black hole

160. Computation of binary neutron star coalescence: Masaru Shibata, Koji Uryu

161. The gravity waves from a pair of neutron stars that spiral together

163. The dawn of gravitational-wave astronomy LIGO, TAMA, GEO, VIRGO,...

164. LIGO’s two detectors: 4km interferometers at Hanford, WA Livingston, LA

167. Postdocs, faculty, research scientists at UWM working on detection of gravitational waves

169. Students involved in research on gravitational waves and relativistic astrophysics

170. einstein@homeeinstein@home: Download a screensaver to let LIGO add your computer to >100,000 others searching current data for gravitational waves from bumps on rotating neutron stars.

171. Google “einstein at home” or go to einstein.phys.uwm.edu