Physcal Science 1st Sem. Learn vocabulary, terms, and more with flashcards, games, and other study tools. What is the definition of "critical density?" Start studying Chapter 14: The Universe. Start studying How Old is the Universe? Exam Review. kkaiser55. A theory of the end of the universe that has it collapsing upon itself. kkaiser55. a) It is about one third the age of the universe. 99 terms. d) It is nearly the same age as the universe. the finite age of the universe. Physical Science 2011 - Sem 2 Final Exam. Pulsar. OTHER SETS BY THIS CREATOR. A star that is highly radioactive and magnetic but very small. Test 3. c) It is about 1% as old as the universe. Olbers's paradox is resolved by. The observable universe is not infinitely old and it has evolved in time. Relative to the age of the universe, how old is our solar system? Learn vocabulary, terms, and more with flashcards, games, and other study tools. A neutron star than spins and emits radio waves. 54 terms . The exact density of matter in the Universe required for the gravitational pull of the galaxies on each other to bring a halt to the expansion of the Universe. 25 terms. b) It is between about 5 and 10% as old as the universe. Life Science. Neutron star.