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The Universe, Space-Time, and Space Travel by Prof. Lyle N. Long http://www.personal.psu.edu/lnl April 25, 2016 April 25, 2016 Topics Vastness of space Relativity Space-Time Gravity Waves Issues in space travel Missions to Mars Missions to other stars and solar systems Life on Other Planets UFO’s? Vastness of Space Humans have great difficulty in understanding the vastness of space and time. Electron: 10-16 meters Molecule: 10-9 meters Insect: 10-3 meters Town: 103 meters Distance to moon: 108 meters (1.3 sec. light to earth) Distance to Sun: 1011 meters (500 sec. light to earth) Solar system: 1013 meters Alpha Centari: 1016 meters 42 orders of magnitude! (.001 lightyears) (4 lightyears) Andromeda Galaxy: 1022 meters (107 lightyears) Universe: 1026 meters (1011 lightyears) 1,000,000,000,000,000,000,000,000,000,000,000,000,000,000 History and Future of Universe http://www.sciencealert.com/this-timeline-shows-theentire-history-of-the-universe-and-where-it-s-headed http://www.sciencealert.com/watch-this-3-minuteanimation-will-change-your-perception-of-time? utm_source=Article&utm_medium=Website&utm_camp aign=InArticleReadMore Distances 1 AU=~93 million miles 1 LY = ~63,000 AU Launched in 1977 Voyager will reach this star in 40,000 years http://voyager.jpl.nasa.gov/where/ Hawking and Mlodinow (& me) at Caltech • • • • Hawking, A Brief History of Time Hawking and Mlodinow, A Briefer History of Time Hawking and Mlodinow, The Grand Design Mlodinow, Feynman’s Rainbow The Universe “The Universe can be defined as everything that exists, everything that has existed, and everything that will exist.” “Radio messages sent from Earth may never reach some regions of space, even if the Universe were to exist forever: space may expand faster than light can traverse it.” 13.8 billion years old (earth is 4.5 billion years old) About 91 billion light years in diameter Maxwell’s Equations Einstein’s Equations From his notebook Einstein’s Field Equations Set of 10 equations in Albert Einstein's general theory of relativity that describes the fundamental interaction of gravitation as a result of spacetime being curved by matter and energy. First published by Einstein in 1915 as a tensor equation. Reduces to Newton’s law of gravitation when gravity is small and speed is much less than speed of light. Led to the prediction of the existence of blackholes and gravitational waves. Relativity Speed of light: 300 million meters/sec. (186,000 miles/sec. or 670 million MPH) 20% speed of light is 9300 miles/sec. (33 million miles per hour or 60,000 km/sec.) Nothing can go faster than this As you approach speed of light: time slows down objects appear shorter mass increases mass = m 1− ( v c ) 2 length = L 1− ( v c ) 2 Relativistic Length Contraction 20% gives 196 ft. Space-Time Blackholes Blackholes seem to exist in all galaxies Massive Blackhole detected recently: Its diameter is about 80 billion miles. It would take light 4 days to travel that distance. And it is 1000 times larger than the distance from the earth to the sun. But the effect of the black hole on other planets is so enormous, that is effect reaches out 3000 light years. Thats how they found it, they saw the enormous effect it was having on nearby stars. Blackholes Blackholes Laser Interferometer Gravity-Wave Observatory (LIGO) LIGO LIGO Laser Interferometer Gravity-Wave Observatory Measures extremely small changes in space-time https://www.ligo.caltech.edu/ LIGO Detected two black holes colliding Gravity Waves Detected The signals came from two merging black holes, each about 30 times the mass of our sun, lying 1.3 billion lightyears away. These are waves in the very fabric of space and time. Measurements agree with Einstein’s theory, computed on supercomputers. Feb. 11, 2016 Issues in Space Travel Distance to nearest star (Alpha Centauri): 41 trillion km (4.35 lightyears) Time to get there at 40,000 km/hr (25,000 MPH): 117,000 years Time to get there at 20% speed of light (216 million km/hr): 22 years If there really are UFO’s, they’d have to deal with these realities also. Issues in Space Travel Distance to nearest habitable planet (Kepler-186f): 4700 trillion km (500 lightyears away) Time to get there at 40,000 km/hr (25,000 MPH): 13 million years Time to get there at 20% speed of light (216 million km/hr)): 2500 years If there really are UFO’s, they’d have to deal with these realities also. Apollo & Saturn V Rockets Cancelled Saturn V Rocket 1966 – 1973 Launched 13 times with no loss of crew or payload Still holds record for biggest payload: 310,000 lb Designed under the direction of Wernher von Braun and Arthur Rudolph at the Marshall Space Flight Center in Huntsville, Alabama, with Boeing, North American Aviation, Douglas Aircraft Company, and IBM as the lead contractors. A total of 24 astronauts were launched to the Moon, three of them twice, in the four years spanning December 1968 through December 1972. Saturn V Rocket Saturn V https://www.youtube.com/watch?v=FzCsDVfPQqk Apollo Spacecraft Apollo Command Module DOD Spaceplane: X-37B X-37 DOD Spaceplane: X-37B DOD Spaceplane: X-37B Started at NASA 1999 Transferred to DARPA 2004, and became classified program First launched into orbit 2010 Launched using an Atlas V rocket Was in orbit for 675 days, ending in 2014 Was launched in May, 2015 and is still in orbit (USA-261) Not known what its purpose is, but probably reconnaissance or as a space weapon Can land autonomously at Vandenberg AFB http://www.n2yo.com/satellite/?s=40651 You can track X-37B’s location Energy Requirements Energy in 45 cal. Handgun 45 cal. bullet: mass = ~15 grams Kinetic Energy: ½ m V2 Speed: 300 m/sec (speed of sound 343 m/sec) Energy: ½ * 0.015 * (300)2 = 675 Joules Browning 50 cal. machine gun has 15,000 Joules Energy of Saturn V rocket from “How Apollo Flew to Moon,” by W.D. Woods Energy Requirements Kinetic Energy: ½ m V2 Apollo 7 Command Module weighed 12,000 lbs (5600 kg) Speed: 25,000 MPH (40,000 km/hr or 11 km/sec) Energy: ½ * 5600 * (11,000)2 = 300 billion Joules Speed: 20% speed of light [60,000 km/sec] Energy: ½ * 5600 * (60,000,000)2 = 1019 Joules (you’d need 34 million Saturn V rockets !!) Energy in Grain of Sand What if we had a grain of sand (0.03 g) travelling at 20% speed of light? Kinetic Energy: ½ m V2 Speed: 20% speed of light [60,000 km/sec] Energy: ½ * 0.00003* (60,000,000)2 = 54 * 1019 Joules About same energy as a Saturn V rocket How about Sustained Acceleration over many Years using Sun? Solar sails: A solar sail in space works almost like a ship sailing on the seas. Engineers can use photons emitted by a star to both propel and steer a spacecraft. – http://www.space.com/22442-solar-sail-starship-interstellar-spacecraft.html For a 30x30 square meter sail, the light force from sun is only about 0.01 Newtons (0.002 Lb-f) For a nano-spacecraft of 50 g (about ½ of iPhone 5): acceleration = 0.01 / .05 = 0.2 m/s2 To reach 20% of speed of light would take 9 years (but as it travelled away from sun the force would get smaller and smaller) How about Sustained Acceleration over many Years using Lasers from Earth? Lets say you want your 0.05 kg spacecraft to reach 20% of speed of light in 1 week You’d need acceleration of about 100 m/s2 So you’d need a force of about 5 Newtons This is about 500 times more photons than from the sun Proposed Mission to Nearest Star: StarShot Milner, Hawking, and Zuckerberg $100M project to travel to nearest star Nearest star is 25 trillion miles away (4.3 lightyears) Using traditional rockets would take 30,000 years to get there If they could reach 20% of speed of light, it would only take 20 years and 4 years to get data back Nano-spacecraft powered by laser beams from earth http://www.nytimes.com/2016/04/13/science/alpha-centauribreakthrough-starshot-yuri-milner-stephen-hawking.html?_r=0 https://www.youtube.com/watch?v=U2zCo6MCcCA https://www.youtube.com/watch?v=c7VPHGjT8A4 Proposed Mission to Nearest Star: StarShot Yuri Milner mail.ru $5.6 billion company Physicist turned investor How about Sustained Acceleration: Ion Thrusters Chemical rockets are great for breaking from earths gravitation, but they require an emormous amount of fuel, not useful for interstellar travel Ion thrusters very high specific impulses (thrust per mass rate) Very small thrust but they can can run for very long time Small amount of mass but particles leave with very high velocity • Konstantin Tsiolkovsky in 1911 • Robert H. Goddard's notebook, September 6, 1906. • The first experiments by Goddard at Clark University from 1916–1917. Hubble Space Telescope Similar in design to KH-11 spy satellite Edwin Hubble 1889-1953 American astronomer who played a crucial role in establishing the field of extragalactic astronomy and is generally regarded as one of the most impor tant observational cosmologists of the 20th century. Hubble is known for showing that the recessional velocity of a galaxy increases with its distance from the ear th, implying the universe is ex p a n d i n g , [ 2 ] k n ow n a s "Hubble's law" although this relation had been discovered previously by Georges Lemaître, who published his work in a less visible journal. https://en.wikipedia.org/wiki/Edwin_Hubble Hubble Telescope Hubble Space Telescope $2.5 billion, Launched April 24, 1990 1.2 million observations since its mission began in 1990. More than 12,800 scientific papers, making it one of the most productive scientific instruments ever built. It takes pictures as it whirls around Earth at about 17,000 mph at 340 miles altitude, has traveled more than 3 billion miles 24,000 pounds at launch Hubble's primary mirror diameter is 2.4 meters (7 feet, 10.5 inches) 13.3 meters (43.5 feet) long – size of a large school bus. Very similar to Keyhole spy satellites (KH-11) http://hubblesite.org/ Johannes Kepler, 1571-1630 • Known for his three laws of planetary motion • Kepler’s work formed the basis for Isaac Newton’s theory of gravity. • Devised the eyeglass for farsightedness and nearsightedness (founder of modern optics). • Invented the Keplerian Telescope, an enhanced version of the refracting telescope. • Kepler’s book "Stereometrica Doliorum" was the foundation of integral calculus Kepler Space Telescope http://kepler.nasa.gov/ http://ssd.jpl.nasa.gov/horizons.cgi Kepler Space Telescope To find terrestrial planets (i.e., those one half to twice the size of the Earth), especially those in the habitable zone of their stars where liquid water and possibly life might exist. When a planet crosses in front of its star as viewed by an observer, the event is called a transit. Transits by terrestrial planets produce a small change in a star's brightness of about 1/10,000 (100 parts per million, ppm), lasting for 1 to 16 hours. T Launched Mar. 6, 2009 using Delta II rocket http://kepler.nasa.gov/ http://ssd.jpl.nasa.gov/horizons.cgi Planets Discovered So Far Goldilocks Zone An important part of this research is the continuing investigation into exactly where a star's habitable zone starts and stops. The habitable zone is the belt around a star where temperatures are ideal for liquid water -- an essential ingredient for life as we know it -- to pool on a planet's surface. Earth lies within the habitable zone of our star, the sun. Beyond this zone, a planet would probably be too cold and frozen for life (though it's possible life could be buried underneath a moon's surface). A planet lying between a star and the habitable zone would likely be too hot and steamy. That perfect Goldilocks planet within the zone wouldn't necessarily be home to any furry creatures. But it would have the potential for some type of life to abound, if even microbes. Discovery of Other Planets Kepler-186f, the first validated Earth-size planet to orbit a distant star in the habitable zone—a range of distance from a star where liquid water might pool on the planet's surface. Less than ten percent larger than Earth, but its mass, composition and density are not known. Previous research suggests that a planet the size of Kepler-186f is likely to be rocky. Orbits its star once every 130 days and receives one-third the energy that Earth does from the sun, placing it near the outer edge of the habitable zone. If you could stand on the surface of Kepler-186f, the brightness of its star at high noon would appear as bright as our sun is about an hour before sunset on Earth. Kepler-186f resides in the Kepler-186 system about 500 lightyears from Earth in the constellation Cygnus. The system is also home to four inner planets, seen lined up in orbit around a host star that is half the size and mass of the sun. Kepler-186f As part of the SETI Institute's search for extraterrestrial intelligence, the Allen Telescope Array had listened for radio emissions from the Kepler-186 system for about a month as of 17 April 2014. No signals attributable to extraterrestrial technology were found in that interval, However to be detectable such transmissions, if radiated in all directions equally and thus not preferentially towards the Earth, would need to be at least 10 times as strong as those from Arecibo Observatory.[7] Signals would be 500 years old if they were detected SpaceX “SpaceX designs, manufactures and launches advanced rockets and spacecraft. The company was founded in 2002 to revolutionize space technology, with the ultimate goal of enabling people to live on other planets.” www.spacex.com Elon Musk SpaceX SpaceX could reveal plans for a Mars mission sometime in 2016, CEO Elon Musk has said. He said he hopes to introduce commercial spaceflights that will essentially transport people to Mars by 2025. He said he plans to travel to the International Space Station (ISS) on board one of his own SpaceX aircraft by 2020. The firm will also be focusing on exploring space travel to and beyond Mars and might make its plans public by September. www.spacex.com Blue Origin: Astronaut Experience (Jeff Bezos, of amazon.com) https://www.blueorigin.com/ Missions to Mars U.S.: ~2030 https://www.nasa.gov/ content/journey-tomars-overview http://www.nasa.gov/ sites/default/files/ atoms/files/journey-tomars-nextsteps-20151008_508.p df Missions to Mars Distance to Mars (closest approach): 35 million miles (56 million km) But spacecraft don’t travel in straight lines between planets Previous spacecraft have taken 128 – 333 days Hohmann Transfer Life on Other Planets? Scientists detected an Earth-like planet 14 light-years away. Its size, orbit, sun, and age provide the "opportunity for life to arise somewhere on the surface ... should all the necessary ingredients and conditions for life on this planet [exist]," one scientist said. Drake equation allows us to estimate how many alien civilizations might exist in the Milky Way: N=R*(fp)(ne)(fl)(fi)(fc)L This predicts anywhere from 0.014 to 140,000 possible civilizations in Milky Way (using pessimistic to optimistic numbers). There are roughly 100 billion galaxies in universe. So there are roughly from 109 to 1016 possible civilizations in universe? They could easily be thousands of years ahead or behind us in evolution and technology Wormholes in Universe Will very likely win Nobel prize next year for detecting gravity waves with LIGO Kip Thorne, Black Holes and Time Warps Wormholes A wormhole is a theoretical passage through space-time that could create shortcuts for long journeys across the universe. Wormholes are predicted by the theory of general relativity. But wormholes bring with them the dangers of sudden collapse, high radiation and dangerous contact with exotic matter. “This analysis forces one to consider situations... where there is a net flux of lines of force, through what topologists would call "a handle" of the multiply-connected space, and what physicists might perhaps be excused for more vividly terming a "wormhole”.” — John Wheeler in Annals of Physics discovered by Ludwig Flamm in 1916 Theoretically possible, called an Einstein–Rosen bridge But has never been observed Kip Thorne, “Black Holes and Time Warps” UFO’s & Alien Visits? Unless we discover wormholes thru space-time, UFO’s will have same problem we have. (30 years to travel to nearest start at 20% speed of light and enormous energy requirements) To support life (like us) for 30 years, spacecraft would need to be quite large, although a large one could also carry small spacecraft many UFO sightings could easily be secret U.S. aircraft or spacecraft Other life forms could easily be more advanced than us. We’ve only had spacecraft for about 60 years, and that is nothing compared to age of planets. Top10 unexplained UFO’s: https://www.youtube.com/watch?v=eq7fecg5K2c http://www.listzblog.com/ unexplained_ufo_sightings_alien_encounters.html https://www.cia.gov/news-information/blog/2016/take-a-peekinto-our-x-files.html SETI Search for Extraterrestrial Intelligence (SETI) https://en.wikipedia.org/wiki/ Search_for_extraterrestrial_intelligence http://www.seti.org/ SETI On 13 February 2015, scientists (including David Grinspoon, Seth Shostak, and David Brin) at an annual meeting of the American Association for the Advancement of Science, discussed Active SETI and whether transmitting a message to possible intelligent extraterrestrials in the Cosmos was a good idea;[1][2] That same week, a statement was released, signed by many in the SETI community, that a "worldwide scientific, political and humanitarian discussion must occur before any message is sent".[3] On 28 March 2015, a related essay was written by Seth Shostak and published in the New York Times.[4] http://www.seti.org/ Conclusions Very exciting time Distances and times involved are staggering Humans will get to Mars this century, hopefully Might be missions to other stars also Will need new propulsion techniques for interstellar travel References Hawking, A Brief History of Time Hawking and Mlodinow, The Grand Design Kip Thorne, Black Holes and Time Warps http://en.wikipedia.org Many many websites…