Are We Alone? 17-Oct-13 Phys 192 Lecture 6 1

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1 Are We Alone? 17-Oct-13 Phys 192 Lecture 6 1

2 UFO Detectives I saw a UFO about 3 years ago. Can you guess what I saw? 17-Oct-13 Phys 192 Lecture 6 2

3 Exercise Break into groups of 3 or 4 Nominate a scribe For this exercise, assume there is intelligent alien life elsewhere in the universe. Consider the following questions What are the issues that you think would make it unlikely for alien life to visit us? What are the issues that you think would make it likely for alien life to visit us? 17-Oct-13 Phys 192 Lecture 6 3

4 A Face On Mars Credit: The Viking Project, NASA APOD: 1998 April 6 17-Oct-13 Phys 192 Lecture 6 4

5 The Face on Mars Credit: NASA,Viking Project, APOD: 1995 July Oct-13 Phys 192 Lecture 6 5

6 Mars Express Close-Up of the Face on Mars APOD: 2006 September Oct-13 Phys 192 Lecture 6 6

7 Mars Express: Return to Cydonia Credit: G. Neukum (FU Berlin) et al., Mars Express, DLR APOD: 2006 September Oct-13 Phys 192 Lecture 6 7

8 Extraordinary claims require extraordinary evidence Dr. Pitts, I noticed that you will be presenting a lecture entitled The Physics of UFOs. I am not attending the lecture, but would like to know if you have written an article on this topic and, if so, whether it is available for people to read. On the basis of what I have read, there seems to be a fair amount of evidence based on (a) reports from highly reliable witnesses (including former military people, police officers, and pilots) (b) physical trace findings, and (c) radar recordings, which support the hypothesis that at least some reported UFOs are highly technologically advanced craft that may have an extraterrestrial origin. The Extraterrestrial Hypothesis seems plausible for explaining at least some reported UFO sightings. I have also discovered that there is much evidence supporting the hypotheses that our planet Earth is not flat and is not located at the centre of the universe. No testimony is sufficient to establish a miracle, unless the testimony be of such a kind that its falsehood would be more miraculous than the fact which it endeavors to establish -David Hume s maxim 17-Oct-13 Phys 192 Lecture 6 8

9 Outline Discussion of manned spaceflight. How does it relate to science/pseudoscience? Some universal background info Size, scale of the galaxy Where did the elements come from? Good planets to support life. Development Do good planets develop life? Does life naturally evolve towards intelligence? Does intelligence produce technology? Searching UFOs/Alien abuductions 17-Oct-13 Phys 192 Lecture 6 9

10 National Research Council, 2008 At the present time, given current knowledge, the level of radiation astronauts would encounter would not allow a human crew to undertake a Mars mission and might also seriously limit long-term Moon activity. International Space Station astronauts receive a radiation dose that is 27 times higher than we receive on Earth s surface. The ISS is still protected by Earth s magnetic field and upper atmosphere. 17-Oct-13 Phys 192 Lecture 6 10

11 Galaxies Our sun is a small star toward the outside of the galaxy, the Milky Way (a spiral galaxy) containing approximately 200,000,000,000 stars (2 x ) A few others (e.g. Andromeda) visible to naked eye Telescopes reveal many galaxies, each ~ stars Andromeda Spiral Galaxy m Oct-13 Phys 192 Lecture 6 11

12 The Milky Way Galaxy 100,000 light years You are here (approximately) 17-Oct-13 from Atlasoftheuniverse.com Phys 192 Lecture 6 12

Views from the Hubble Telescope Picture of an area of the sky (the size of a grain of sand held at arm s length) in which there are no stars visible to the naked

13 Views from the Hubble Telescope Picture of an area of the sky (the size of a grain of sand held at arm s length) in which there are no stars visible to the naked eye! Shows visible stars in the Milky Way and distant fuzzy looking galaxies Estimate: ~10 11 =100 billion galaxies in the universe 17-Oct-13 Phys 192 Lecture 6 13

The big bang (and it s aftermath) produced no element heavier than lithium (atomic

14 Material for Life The earth is teeming with elements: Nitrogen, hydrogen, oxygen, carbon, gold, iron, manganese, H uranium, silver, lithium Atomic # = # of protons The big bang (and it s aftermath) produced no element heavier than lithium (atomic number=3). Hydrogen, helium and lithium only.nothing heavier. 17-Oct-13 Phys 192 Lecture 6 14

15 Heavy Elements Heavy elements are crucial for life. Carbon, oxygen, nitrogen, iron, potassium Where did the heavy elements come from? Normal stars (our sun) typically produce helium from hydrogen, but also produce some lithium and beryllium (Be, atomic #=4) Elements heavier than beryllium require a higher energy process to produce them a supernova. Supernovas occur at the end of a large star s life cycle. The stuff you are made of: carbon, oxygen, silicon, iron, etc. are supernova remnants! 17-Oct-13 Phys 192 Lecture 6 15

16 Supernova Expels matter - all heavy elements in the universe (in you!) are formed in supernovae Remnant is a neutron star or black hole Radiates more energy than an entire galaxy for a brief period (months): Famous supernovae: 0 -- The Christmas Star?? in Crab Nebula, Recorded in China, in large Magellanic Cloud, seen by Kepler Pulsars (Neutron Stars) observed now as remnants of the 1054 and 1572 Supernovae! in Magellanic Cloud - remnants still observed 17-Oct-13 Phys 192 Lecture 6 16

17 Summary About stars per galaxy 2 to 4 x in the Milky Way About galaxies in the universe So we have about: x = = 100,000,000,000,000,000,000,000 stars in the universe. More stars in the universe than grains of sand on Earth Universe is dominated by light elements (H, He, Li) but there are plenty of heavy elements that have been produced by supernovae. 17-Oct-13 Phys 192 Lecture 6 17

18 Question: How many Earth-like planets: Requirements: Good Places for Life Single star system (not binary) Star should be sunlike (similar to our sun) Must have planets Must have Earth-like planet Estimates (arguable, but you can change them!) ~50% are single star systems (not binary) ~10% are sunlike (similar to our sun) ~10% have planets ~10% have an Earth-like planet These two estimates are pretty solid. These two estimates are low, reality possibly much higher. 4x10 11 x 0.5 x 0.1 x 0.1 x 0.1 = 2x10 8 =200,000,000 Earthlike planets in the Milky Way galaxy alone!!! [low estimate] 17-Oct-13 Phys 192 Lecture 6 18

19 Does Life Develop? Experiments show that organic molecules form in conditions similar to the earliest stages of Earth s development. Carbon dioxide, water, nitrogen + energy (heat or lighting) Details of the mechanisms that bring single celled organisms (like amoeba) from the organic molecules are under study. Let s guess that there is only a 1% chance life will develop on an Earthlike planet. [This is probably a low estimate. The likelihood to develop life on an Earthlike planet is probably very high.] 2 x 10 8 Earthlike planets x 0.01 chance of developing life = 2 x 10 6 = 2,000,000 planets with life in the Milky Way. [this is still a low estimate] 17-Oct-13 Phys 192 Lecture 6 19

20 Does Intelligence Develop? Large uncertainty. See Hobson textbook for a discussion. Art Hobson, Physics Concepts and Connections The Drake Equation attempt to account for the likelihood of intelligent life to develop, as well as the lifetime time scale. See Origins web site. 17-Oct-13 Phys 192 Lecture 6 20

21 How Would We Make Contact? Einstein says we can t travel faster than the speed of light. Experiments say he s right. This immediately limits the possibilities for space travel between solar systems that are light years apart. A light-year is a distance measure. Recall: c=3x10 8 m/s d=ct : 1 light-year = 3x10 8 m/s x 3x10 7 s/year =10 16 m Milky Way is about 30,000 light-years wide What can travel at the speed of light? Electromagnetic waves! Light, x-rays, radio-waves. First contact with an intelligent life form would most certainly be through electromagnetic waves! 17-Oct-13 Phys 192 Lecture 6 21

22 Electromagnetic spectrum X-rays and gamma rays are also light! 17-Oct-13 Phys 192 Lecture 6 22

23 SETI Search for Extra Terrestrial Intelligence Scanning the sky for all electromagnetic frequencies Looking for non-random patterns indicating a deterministic source. Note: Humans have been broadcasting to the galaxy since the early 20 th century. Our electromagnetic waves now reach out some 80 lightyears away from us. Anyone farther than 80 light-years would not yet be able to see our broadcasts! About 14,000 stars within 100 light-years of us (= % of the Milky Way) For signals originating elsewhere, our sensitivity depends upon location on time. To see a civilization on the other side of the Milky Way, they needed to begin broadcasting 30,000 years ago! 17-Oct-13 Phys 192 Lecture 6 23

24 How Would We Make Contact? First contact with an intelligent life form would most certainly be through electromagnetic waves! Allen Telescope array, part of SETI = Search for Extraterrestrial Intelligence Project Scanning the sky for all electromagnetic frequencies Looking for non-random patterns indicating a deterministic source. You can participate in SETI at Home (link) 17-Oct-13 Phys 192 Lecture 6 24

25 How Would They Know We re Here? Humans have been broadcasting to the galaxy since the early 20 th century. Our electromagnetic waves now reach out some 80 lightyears away from us. Anyone farther than 80 light-years would not yet be able to see our broadcasts! About 14,000 stars within 100 light-years of us (= % of the Milky Way) For signals originating elsewhere, our sensitivity depends upon location on time. To see a civilization near the center of the Milky Way, they needed to begin broadcasting 25,000 years ago! 17-Oct-13 Phys 192 Lecture 6 25

26 The Milky Way Galaxy 100,000 light years Our electromagnetic footprint is smaller than this dot! The rest of the galaxy has no idea that we are here! 17-Oct-13 from Atlasoftheuniverse.com Phys 192 Lecture 6 26

27 UFOs? Have we been visited? 17-Oct-13 Phys 192 Lecture 6 27

28 UFOs Question: Why are they always seen by untrained observers? Professional astronomers and astrophysicists observe the sky daily with sophisticated equipment have never observed an extraterrestrial spaceship. Question: Why hasn t anyone observed the electromagnetic footprint (radio waves, gamma rays, light, etc.) of an alien? The electromagnetic footprint would be here before the aliens would. 17-Oct-13 Phys 192 Lecture 6 28

29 UFOs: Natural Explanation Some sources that might be misinterpreted: Approaching Aircraft (appear to hover) Unconventional Aircraft High Altitude Balloons Venus Artificial Satellites Reflections Off Clouds Optical Mirages Meteors Uncommon Atmospheric Phenomena (Aurora, Ball Lightning) Secret Military Objects Accidents 17-Oct-13 Phys 192 Lecture 6 29

30 17-Oct-13 Phys 192 Lecture 6 30

31 Roswell Claim of a flying saucer crash in Real explanation likely from Project Mogul, a balloon designed to detect Soviet nuclear testing. Most recent version of the hoax was Alien Autopsy link Films originator refuses to have its age verified. Lot s of debunking, even the believers aren t on board See chapter 6 of Why People Believe Weird Things for an excellent discussion of UFOs and alien abductions. 17-Oct-13 Phys 192 Lecture 6 31

32 Summary Is there life beyond Earth? We don t know. Has extraterrestrial life visited Earth? There is no credible evidence that it has. If we make contact with another civilization, it will be by electromagnetic wave. 17-Oct-13 Phys 192 Lecture 6 32

The Physics of UFOs Kevin Pitts University of Illinois

The Physics of UFOs Kevin Pitts University of Illinois 2-Nov-12 World of Science - UFOs 1 Why UFOs? It all starts at Fermilab 2-Nov-12 World of Science - UFOs 2 2-Nov-12 World of Science - UFOs 3 2-Nov-12