"In the beginning," "There was darkness." "And then, bang," "Giving birth to an endless," "Expanding existence of time," "Space and matter." "Every day, new discoveries" "Are unlocking the mysterious," "The mind-blowing," "The deadly secrets of a place" "We call the universe." "The past and the future:" "The ultimate" "Vacation destinations." "But are they within reach?" "It could happen" "Within a few years" "Or a few decades." "When you travel through time," "Strange things start to happen." "You can imagine" "Warping things so dramatically" "That you can actually" "Visit yourself in the past." "Some humans have" "Already made the trip." "You will have jumped" "Into the future" "While aging very little." "That's really cool." "See how it's possible" "As we unravel" "The mystery of time travel." "The Universe - 5x04 August 19, 2010" "Of all the riddles" "Of the universe," "Time travel" "May be the most perplexing." "Time itself has" "A lot of fascination for us." "So we end up thinking of ways" "Of cheating time" "And things like that," "Going back in time," "Changing things." "Time travel could involve" "Going back in time" "Or speeding into the future." "But for the moment," "Every one of us is frozen" "In the present." "Yet, science holds out" "The possibility" "That we might loosen the hold" "That time has on us." "Einstein's theory of relativity," "In which time plays" "A central role," "Makes time travel" "An open question." "Our best theory of time," "Which is relativity," "Doesn't explicitly" "Forbid time travel per Se." "It might be that there are" "Things we yet don't understand" "That will improve the theory," "But it seems that there are ways" "Of constructing scenarios" "Within relativity" "That allow you" "To go back in time." "Traveling into the past" "Seems improbable" "Because time only goes one way:" "Forward." "Physicists call this" "The arrow of time." "The arrow of time" "Is just the fact" "That you can always" "Orient yourself," "Moving from the past" "To the future." "You remember the past." "You don't remember the future." "You can cause things" "To happen in the future," "But you can't cause things" "To happen in the past." "If you took a movie of things" "Going on in your everyday life," "Like mixing cream" "Into your coffee," "Then you played" "That movie backwards," "It would be perfectly obvious." "Cream mixes into coffee." "It doesn't unmix." "That's the arrow of time." "The arrow makes time" "A one-way street" "Of irreversible events," "Something we know intuitively" "From our everyday experience." "On a pool table, you can break," "But don't expect the balls" "To realign on their own." "You can scramble an egg," "But you can't unscramble it." "The reason why time has an arrow" "Is a fundamental law of physics" "That says all things" "In the universe" "Move from orderly states" "To disorderly states." "As the universe gets older," "As we move from the past" "To the future," "All the differences" "Between the past and the future" "Can be summed up by saying" "That the universe" "Is winding down." "The universe is going" "From being orderly," "Very neatly arranged," "To disorderly and messy." "So if you had a plate," "That was a nice plate," "That was put together" "And orderly, it breaks." "It becomes more disorderly." "That's very natural." "And if you try" "To restore order by" "Gluing the plate back together," "Your actions release" "Enough energy" "Into the surrounding environment" "To create more disorder" "In the universe as a whole." "But e arrow of time" "Can be bent" "In extreme conditions." "It all goes back" "To Einstein's theory" "Of relativity." "Einstein showed that the gravity" "Of massive objects" "Like planets, stars," "Black holes" "Can actually cause" "Space itself to bend." "More amazing than that," "He showed that space and time" "Are actually linked" "Into a single something" "He called spacetime." "This means" "That whenever space is warped," "So is time," "And nothing in the universe" "Can bend spacetime" "More than the supergravity" "Of a black hole." "So you can imagine" "The gravitational field" "Is so strong" "That space and time" "Curl back on themselves." "And you can start at one point," "Go forward in time" "And come back at the point" "That you left." "When the arrow of time" "Bends around to meet its tail," "It creates an endless loop" "In which the same events" "Happen over and over." "So if this is time" "Curling back on itself" "And the universe" "Just repeats itself" "Over and over again," "Every moment in time" "Would just repeat" "An infinite number of times." "An endless loop would become" "Pretty frustrating for anyone." "But suppose a time traveler" "Can land in the past" "Without the constant repetition." "In that case," "There are other roadblocks." "The most perplexing" "Are the inconsistencies," "Or paradoxes, that pop up" "When we start meddling" "With the past." "A famous example" "Of the kind of inconsistency" "You can get with time travel" "Is called" "The grandfather paradox." "And this is where" "Someone goes back" "To the time of, for example," "Their grandfather." "So imagine" "That I go back in time" "With a time machine" "And meet my grandfather in 1937." "He's just about to go" "On a blind date" "With my grandmother." "They've never met before." "But actually, I convince him" "Not to go on that date." "He's actually interested" "In the races," "And so I tell him" "That there's an exciting race" "With seabiscuit that's coming up" "At the Santa Anita track." "And so we go off together" "To that race." "He never meets my grandmother." "So, what happens to me?" "How is it possible" "That I could have been born" "And then been able" "To go back in time, meet him," "And stop myself from being born?" "So, there's an example" "Of an inconsistency." "It's a loop in time" "That really doesn't make sense." "But if time travel" "Is possible," "Nature must have a way" "Around the contradiction." "One thing that physicists" "Are quite certain of" "Is that the universe" "Ultimately makes sense." "In all of physics," "In all of science," "More generally," "Consistency, self-consistency," "Common sense, if you like," "Is something that is" "A fundamental principle." "Physicists have come up" "With at least three ways" "That nature might act to prevent" "Time travel paradoxes." "The first is simple:" "Nature prevents paradoxes" "By making time travel" "Into the past impossible." "In other words," "It can't be done." "A different alternative" "Is the strange idea" "Of multiple universes." "One way of dealing" "With travel back in time" "Is to say" "That you actually enter" "A different parallel universe" "After having made" "The journey back in time." "So you don't affect" "The history of the universe" "From which you came." "In effect," "Anything that can happen" "Will happen." "But the way it happens" "Is by entering" "A parallel universe." "Pretty bizarre thought." "A third solution" "To the paradox problem" "Is the notion" "That if time travel is possible," "You just won't be able" "To change the past" "When you get there." "The science behind this" "Can be illustrated" "By reducing the problem" "To the simplest situation" "You can think of." "For example," "Balls on a pool table." "Let's set up a pool table" "That's like a time machine." "If a ball enters one pocket," "It travels through a wormhole" "And can exit another pocket" "Before it entered" "The first pocket." "So it's a time machine." "So now suppose the ball" "Really does go" "Through the first pocket," "Emerges before it entered," "And then hits itself" "Before it entered" "The first pocket." "That would deflect it," "Preventing it from entering" "The first pocket," "And thus preventing it" "From having exited" "The second pocket" "And done the deflection" "In the first place." "So, it's a paradox." "However, the idea" "Of self-consistent solutions" "Gives us a way out" "Of this paradox." "Suppose that the ball" "Iting the second pocket" "Can only hit itself" "In such a way as to deflect it" "Into the first pocket." "Then the whole loop" "Is self-consistent." "There's no paradox." "We think that nature" "Always somehow manages" "To choose the solution" "That provides self-consistency." "In other words," "You always get a solution" "That does not produce a paradox." "If that's the case" "And Clifford Johnson were able" "To travel to the year 1937," "He might be able to meet" "His grandfather." "But despite his best efforts," "Nothing he does" "Would alter the fact" "That somehow his grandfather" "Will meet his grandmother" "To allow Clifford to be born." "Hi." "How are you?" "How ya doing?" "One way or another," "The universe will prevent him" "From changing history." "But we don't have to worry" "About paradoxes" "When we travel forward," "Taking the arrow of time" "Into the future." "Traveling forward in time" "Is the easiest thing" "In the world." "Every minute, you move" "One minute forward in time." "One thing we can do to change" "How we move forward in time" "Relative to each other" "Is to actually move" "At different velocities" "Compared to each other." "A time machine" "That takes us into the future" "Is based on Einstein's discovery" "About time and speed." "The faster you move in space," "Time, for you, slows down" "As compared to people" "Standing still." "And as mind-bending" "As this seems," "It's actually been proven" "By experiments." "Clocks have been placed" "On rapidly moving airplanes" "And rocket ships," "And they've moved" "Over some distance" "At a very rapid speed." "And when the atomic clocks" "Were measured" "After the end of the journey," "They had progressed" "Forward in time" "A little bit less" "Than similar clocks" "Which had remained at rest" "On earth." "The effect iu called" "Time dilation," "And we can use it" "To travel into the future." "In fact, it's already been done." "Russian cosmonaut," "Sergei Krikalev has logged" "More than 803 days in orbit," "Traveling 17,000 miles an hour," "Making him the world's" "Record holder in time travel," "Though you'd hardly know it" "To look at him." "What's actually happened" "Is that he's about" "A 50th of a second slower" "In the amount of time" "That has passed for him" "Compared to everyone else" "Who's stayed on earth." "But dilation really begins" "To pay off as a time machine" "When you pump your speed to just" "Under the speed of light." "The idea is to let" "Clocks on earth" "Move at their normal speed," "While you're off in space" "And your clock is moving" "More slowly." "When you get back," "You're in the future." "Suppose, for example," "You wanted to go 500 years" "Into the future." "To move 500 years" "Into the future," "You'd have to move at 99.99%" "Of the speed of light" "For 7 years." "When you get back," "You will have aged only 7 years," "But everything on earth" "Will have aged 500." "But one of the biggest problems" "With building a time machine" "For travel into the future" "Is finding enough fuel" "To boost a spaceship" "To speeds that high." "There's no law of physics" "That says you can't go close" "To the speed of light," "But your rocket ship" "Becomes heavier and heavier" "As you go closer and closer" "To light speed." "So you require" "More and more fuel" "To accelerate you" "Smaller and smaller amounts," "And you need more than" "An infinite amount of energy" "To actually break" "The light-speed barrier." "But high speed" "Isn't the only way" "To zip into the future." "Einstein's theory of relativity" "Says high gravity" "Also slows down your clock," "The kind of gravity" "You might find" "Near a black hole." "Let's say" "You're in a spaceship," "And you go and you park yourself" "Just outside a black hole" "For a while." "Once you return to earth," "You will notice" "That many, many years" "May have passed on earth," "But only a few weeks or months" "Will have passed" "In your own frame of reference." "You will have jumped" "Into the future" "While aging very little." "That's really cool." "But spending years" "At high speed" "Or near a black hole" "Is a slow kind of time travel." "For more impatient voyagers," "There may be" "An instantaneous version" "By way of a shortcut" "Through space called a wormhole" "That could also become" "A corridor through time." "To conquer time travel," "We have to tread a long path" "That takes us" "Through bizarre theories" "And incredibly" "Complex technology" "Toward a goal" "That will one day make starships" "Into time machines." "Starships, in fact," "May be our best bet." "Shoot off in a rocket ship" "At super speed" "And let our own time slow down" "While the rest of the world" "Moves on." "We have a vested interest" "In these kinds of adventures." "The high speeds" "That result in time travel" "Are also our only way" "Of smashing a time barrier" "That keeps us" "From traveling to the stars" "Because the distances" "Are so huge." "We would really like" "To be able to traverse" "Giant distances" "In a short amount of time" "In order to explore the universe" "On a human time scale." "Even the nearest stars" "To earth" "Seem impossibly far away." "Alpha Centauri is the closest." "But in this case," "Close amounts" "To 4.3 light-years away, 25 trillion miles," "100 million times farther" "Than the moo" "Today's speediest rockets" "Would need 80,000 years" "To get there." "So the challenge" "Is to get there faster." "But if we're going to use" "High-speed star missions" "As our way to get to the future," "It still doesn't satisfy" "Our dream of getting there" "In a flash." "Achieving time travel" "By moving fast," "And so slowing your clock down" "Relative to everyone else," "Is a way of achieving" "Time travel." "It's a little bit" "Like rip van winkle did" "By going to sleep" "And then waking up later" "And it's the future." "But some might think of that" "As cheating in a way." "It's not really the time travel" "That we think of" "Where we perhaps go" "Through a portal" "Or flick a lever on a machine" "And then end up" "At a different time." "Physicists did" "Important theoretical work" "On instantaneous time travel" "In the 1980s" "While helping Carl Sagan," "Who was writing his novel," "Contact." "The book imagined space travel" "Faster than light" "Through a corridor in space" "Called a wormhole." "awormholeis" "A kind of shortcut" "Between two different parts" "Of space," "Which can be very far away" "Or they can actually" "Be close to each other." "But the key idea is that" "You can traverse the wormhole" "By simply going in" "Through the entrance," "One side of it," "And coming out the other side." "incontactandmanyother" "Science fiction scenarios," "Wormholes are used as tunnels" "To travel huge distances" "Across the universe" "To other stars." "But a wormhole" "With openings close together" "Is a much better starting point" "For a time machine." "Suppose I have a wormhole" "Right next to me." "If I put my arm into it" "Like this," "It would emerge over there." "A wormhole is a great ingredient" "For constructing a time machine." "A wormhole time machine" "Would use the same" "Rip van winkle trick" "As the very fast spaceship." "Super speed" "Makes your clock slow down..." "While everyone else" "Keeps on going." "It works" "Because both ends" "Of the wormhole always have" "The same date and time," "No matter what happens to them." "You can take one end" "Of the wormhole" "And put it on a rocket ship" "Or something and send it off" "At very high speed" "And then back." "So what happens is that," "When it returns," "It's in the future." "A traveling wormhole opening" "From the year 2010" "Might end up returning to earth" "In the year 2510." "Because its clock was so slow," "It aged very little," "While the rest of the world" "Aged 500 years." "So now if I walk" "Into the end of the wormhole" "That's in the past," "The end that didn't go" "On the rocket ship," "I can come out the other end" "And I'd be in the future." "Although each step" "Of this scenario" "Might be really hard to achieve" "With any technology" "We can imagine," "It's all internally consistent" "In the laws of gravity" "And space and time" "That we understand so far." "So that wormhole time machine" "Is, we would say," "A consistent solution" "Of the equations" "Of space and time." "The wormhole time machine" "Would work in reverse too," "Making time travel" "Theoretically possible" "From the future" "Back into the past," "Where you started." "Well, let's face it." "Most people" "Are interested in the idea" "Of going backwards in time" "Because they want to fix things." "The interesting thing" "Is, though, that we can," "Using the laws of physics," "At least explore" "What it would be like" "To travel backwards in time." "And although we are" "Preoccupied with time machines," "It may be that time travel" "Is possible through wormholes" "That are natural in origin." "Another possibility," "If we can't make time machines," "Is that maybe nature" "Has already made them" "And we just" "Have to discover them." "What could have happened is that" "In the very early universe," "The nature of space and time" "Was already twisted up" "In such a way" "That some of that got frozen in," "Leaving time loops" "That we might be able to use" "As time machines" "Sometime in the future." "So it's an interesting" "Possibility" "That we don't actually" "Have to create these things." "But what if we are left" "To our own resources?" "Can we build" "A time machine at all?" "If theory says" "A wormhole is the way to go," "Then what does it take" "To make one?" "Wormholes are" "Speculative ideas." "We can write down the equations" "That describe them." "We don't expect to bump" "Into one in astronomy" "Or anything like that," "But we could be surprised." "Where we do expect" "Wormholes to exist" "Is at the submicroscopic level," "Where space and time" "Are fluctuating wildly." "So what people imagine" "Is somehow capturing" "A microscopic wormhole" "And growing it to a larger size." "We don't know" "If that's possible." "We have no idea how to do that," "But that's probably" "What it would take" "If you wanted" "A big-sized wormhole." "The technology we need" "To manipulate a wormhole" "May seem impossibly remote." "But for those willing" "To let their imaginations roam," "There's a glimmer of hope" "In at least one place." "It's where space, time" "And the nature of existence" "Itself" "Meet in head-on collisions" "Inside the biggest," "Most complex machine" "Ever created by man." "Where does the universe hide" "The secrets that might tell us" "How to travel in time?" "Our exploration has taken us" "Through the world of wormholes" "And their possibilities" "As time machines," "And now we're in search" "Of the technology" "That might make space travel" "And time travel" "Two sides of the same coin." "If there's nothing on earth" "That comes close" "To being a time machine now," "There is something" "That might one day lead us" "To new laws of physics" "That help us determine" "If it's at least possible." "It explores the universe," "Not in the realm" "Of the cosmic web" "And its galaxies," "But in the domain" "Of quantum physics," "Involving particles at sizes" "More than a million times" "Smaller than the smallest atom." "It's the newest tool" "At the frontier of physics" "Called the large" "Hadron collider." "The large hadron collider" "Is the largest," "Most complicated machine" "Ever created by humankind," "And its role is to help us" "Study the frontier" "Of particle physics." "What it actually does" "Is it accelerates protons" "In two directions" "Around the ring," "One way round" "And the other way round," "To nearly the speed of light" "And then collides them." "The collider went operational" "In November 2009," "And as scientists" "Ramped up the power," "The energy in its collisions" "Was increased almost tenfold" "By March 2010," "And it will double that" "Sometime after 2013." "Today's theories" "Of space, time, gravity" "And quantum physics" "Are still incomplete," "And tools" "Like the large hadron collider" "Will help fill in" "The ever-puzzling blanks." "This is where we expect that," "If there's some missing physics" "That we need" "To understand spacetime" "In a way that will tell us" "Whether time travel is possible" "Or restricted in various ways," "This is where we expect" "The new results to come from." "The goal is to figure out" "How rules governing" "The tiniest particles" "In existence" "Also apply to the biggest things" "Like stars, galaxies" "And the expanding" "Universe itself." "Without understanding this," "Building a time machine" "Might be harder" "Than trying to build a radio" "Without knowing about" "The existence of electricity." "There are many physicists" "In the world who believe" "That this understanding" "Is in fact" "Right around the corner," "That it could happen" "Within a few years" "Or a few decades." "On the other hand," "It could be that" "This problem is in fact" "Much harder than we think" "And that human civilization" "Will simply not live long enough" "To figure out how it works." "The large hadron collider" "Might also reveal" "Extra dimensions" "That could play a role" "In time travel." "We live in three dimensions" "Of space." "If we lived" "In only two dimensions," "Our universe" "Would be a flat sheet." "A sphere would look like" "A circle to us." "The third dimension" "Would be there," "But just hidden from our view." "If dimensions other than" "Our familiar three" "Are really there," "They, too, are hidden." "If we were to find" "Experimental evidence" "For the existence" "Of other dimensions" "And if we were to be able" "To explore the meaning" "Of these other dimensions" "And see how they come about," "It could be that far," "Far in the future," "This new physics" "Would be utilized" "To come up with" "Some new form of travel" "That allows us" "To at least get close" "To the speed of light barrier," "If not surpass it." "Getting close to light speed" "May be the most promising way" "To travel in time" "By slowing down our clocks." "In this respect," "The large hadron collider" "Is leading the way," "Even if its first step" "Is an extremely small one." "The large hadron collider" "Is 17 miles around," "And it accelerates protons" "To nearly the speed of light." "If you wanted to do that," "But with human beings," "A rough calculation shows" "You'd have to scale it up" "To a thousand light-years around" "In order to do the same thing." "This is like saying" "That the spacecraft" "Powerful enough to carry us" "To the stars at that speed" "Would be bigger" "Than the distance" "We need to travel," "Big enough, in fact, to enclose" "The nearest 100,000 stars." "Back on earth," "The physics of light speed" "And beyond" "Meets surf culture on the beach" "In Malibu, California." "Richard Obousy is one" "Of the few physicists" "Who have worked on the concept" "Of faster-than-light warp drive." "A warp ship, he says," "Rides a wave-like ripple" "Of warped space," "Almost as a surfer" "Rides a wave of water." "A great analogy" "Is with that of a surfer" "Riding a wave of seawater." "So just as the wave behind it" "Sort of rises up" "And pushes this surfer" "Through the ocean," "I think it's a great analogy" "With how a spacecraft" "Is mutually pulled and pushed" "Through the fabric of space." "The idea is based, in part," "On the fact" "That space in the universe" "Is expanding." "If we can make it" "Expand at will," "We may be able to propel" "A warp ship." "We make space expand" "Behind the ship" "And make it contract in front." "The wave of warped space" "Moves through the universe" "Faster than light," "While inside" "A so-called warp bubble," "The ship is a passenger," "Never violating Einstein's rule" "Against exceeding" "The speed of light." "While warp drive" "Is mostly science fiction" "At this point," "There is some physics behind it." "Mexican physicist" "Miguel Alcubierre" "Worked out the complex math" "To support it in 1994." "Unfortunately," "There's nothing in the math" "That tells us how to do it." "And though most scientists" "Have major doubts," "Not all the skeptics" "Are writing off" "Warp drive completely." "Warp bubbles" "May be impossible, they say." "But what about" "Super advanced beings" "Building faster than light" "Warp drive bullet trains" "To the stars" "And through time?" "In searching for the secrets" "Of time travel," "We inevitably meet" "The idea of warp drive" "Or other strategies" "For traveling faster than light." "It's the most" "Sought-after solution" "To the dream of star travel" "And potentially" "Turning any spaceship" "Into a time machine." "The most optimistic views" "Of the future" "Paint a picture of spaceships" "Riding warp bubbles" "As easily as expert surfers" "Catch waves" "Off the beaches of earth." "But even optimistic physicists" "Must face some harsh realities." "If surfing is an analogy" "For how a warp ship might work," "Then watching a beginning surfer" "Drives home a better point:" "Achieving warp drive" "Is very difficult." "This morning," "I had my first surfing lesson" "And had this idea that," "In some sense," "We were gonna be able" "To manipulate," "In some sense, nature" "And that I was gonna be able" "To ride this wave" "And it was gonna carry me" "At great velocities" "Across the ocean." "But the reality is that" "The ocean manipulated me." "It was far harder to control" "Than I originally anticipated." "And control" "Is a real problem," "Because science says" "A warp ship just can't make" "Its own warp field." "One of the often" "Cited problems" "With the warp drive model" "Is the ship would be" "What we call" "Causally disconnected" "From the bubble." "That is, it could never find" "A way to communicate" "With the bubble." "And so it could never turn" "The bubble off" "Once it had started." "But what would happen" "If the starship" "Did not have to worry" "About turning its bubble" "On and off?" "What you might imagine," "For a sufficiently" "Advanced civilization" "And given sufficient" "New laws of physics," "Would be some kind of" "Warp-drive escalator" "Or corridor, and then" "When you would drop a ship" "Into the prearranged warp tube," "If you will," "It might be able to ride" "Some wave along to the end." "It would be like" "A bullet train to the stars." "Its passenger cars might travel" "Faster than light," "But whoever invents it" "Would need thousands of years" "At sub-light speeds to build it" "And use more energy" "Than we can imagine." "We would probably" "Need to harness" "At least the energy output" "From an entire star," "If not a lot more than that." "So these are things we can" "Talk about hypothetically," "But no one has" "An engineering program" "To make it happen." "When astronomers" "Recently discovered" "That the expansion" "Of the universe is accelerating," "They reasoned it was driven" "By a mysterious dark energy" "That is part of space" "Everywhere." "A few people have suggested" "That dark energy" "Can be harnessed" "As a power source" "For exotic devices" "Like starships or time machines." "We don't really know" "What the dark energy is." "So it's not clear" "That we will never be able" "To harness it." "However, the leading models" "Suggest that it's either" "A property of space itself" "That can't be changed" "Or some sort of an energy field" "Which is of such low density," "There's so little of it" "Per unit volume," "That harnessing" "Interesting amounts of it" "Will essentially be impossible." "The bottom line" "When it comes to warp drives," "Wormholes or time machines," "Leads many scientists" "To reject them out of hand." "Can we be sure" "That they're right?" "Though we think" "We know a lot" "About the universe right now," "And we do," "There have been many times" "In the history of physics" "When we've been burned" "By having too much" "Of a self-assured sense" "Of knowing it all." "There really are" "Laws of physics" "That we can't violate," "But there's also technology." "You say, well," "This is just too hard." "We'll never be able to do it." "And there, when scientists say" "Things like that," "They're almost always wrong." "It's much safer for us to say," "Here are what" "The laws of physics" "Allow us to imagine doing." "Hopefully, someday" "In the future" "We'll build the technology" "That makes it happen." "And as we've seen," "That future may confront us" "Very soon," "As astronomers search" "For planets around stars" "Outside the solar system." "The closest star system to earth" "Has a binary pair of stars." "Is that a good place" "To search for planets?" "That's just what Nicole" "Of Oklahoma city, Oklahoma," "Wanted to "ask the universe,"" "When she wrote..." "Nicole," "That's a really cool question." "It turns out that a planet" "In a binary system can orbit" "Either one of the two stars" "Very closely" "Or it can orbit both of them" "From very far away," "But it can't orbit among them." "It can't do a figure eight" "Among them, for example." "That trajectory is unstable" "And the planet" "Would quickly get ejected." "We may be on the verge" "Of discovering" "An earth-size planet" "Around one of the two stars" "In the Alpha Centauri system," "The sun's nearest neighbor." "It would be" "A more compelling reason" "Than ever before" "To explore the exotic science" "Of high-speed space voyages" "And the time travel" "That goes with them." "Alpha Centauri" "Is very exciting" "Because it now appears" "From a variety of different" "Computer simulations," "That it's quite possible" "That there could be" "Terrestrial mass planets" "Orbiting both components" "Of the Alpha Centauri" "Binary system." "Alpha Centauri "a" and "b"" "Are so distant," "They look like a single star" "From earth," "But they're actually" "A binary pair." "A third member of the system" "Is Proxima Centauri," "A red dwarf loosely bound" "To the main pair." "If you're sitting on a planet" "In the Alpha Centauri "a" system" "Or the Alpha Centauri" ""b" system," "Proxima Centauri" "Wouldn't even be visible" "In your night sky." "It's that dim." "Alpha Centauri "a" and "b"" "Orbit around each other." "At their closest point," "They're about 20% farther" "Than the distance" "From the sun to Saturn." "At their farthest," "They're 20% more distant" "Than the sun is from Neptune." "Each has a habitable zone" "Similar to the sun," "Where life-bearing planets" "Could exist." "And that, after all," "Is a Holy grail in astronomy." "Well, a trip" "To the nearest stars," "For example, Alpha Centauri," "That we can do" "Within our lifetimes" "Would be immensely exciting." "One of the great goals" "Of science is to find life" "Elsewhere in the universe." "What better place to start," "Other than our solar system," "Than the nearest star?" "But now space travel" "Becomes time travel" "As we set our sights" "On a mission that can be done" "Under the laws of physics" "We now know:" "A mission that can cross" "More than 4 light-years of space" "In just 45 days." "Our quest" "To unravel the mysteries of time" "Now point us again" "To Alpha Centauri," "The sun's closest neighbor." "It is the most likely" "First destination" "For a starship from earth," "A starship" "Whose mission cannot avoid" "A component of time travel." "We have no idea" "What kind of technology" "Would actually take us from here" "To Alpha Centauri and back." "Therefore, we might as well" "Be optimistic and say" "That we just move at 99.99%" "The speed of light" "All the way there" "And then all the way back." "The ship seems" "Surprisingly small" "For one that has to make" "Such a long trip." "How can it hold enough supplies" "To support a crew" "For the duration?" "It can, because it is" "Not only a starship," "It is also a time machine." "It would take" "About 8.6 years," "Because Alpha Centauri" "Is 4.3 light-years away." "But to the people on the ship," "It would take" "Less than two months." "It would take about 45 days" "Because they're traveling" "Close to the speed of light." "The astronauts would also" "Have to overcome the problem" "Of killer acceleration" "In quickly reaching" "The speed of light." "Otherwise," "They'd have to speed up slowly," "Adding time to the total trip." "Alpha Centauri" "Is the go-to destination" "For earthbound beings," "Hoping for a toehold" "In star travel." "It's no accident" "That James Cameron" "Chose it as home" "To his fictional moon, Pandora," "In the movie avatar." "The reason we would go" "To Alpha Centauri" "Has to do with today's" "Intensive telescope search" "For earth-like planets" "Around Alpha Centauri "b,"" "One of two stars" "In the system's" "Main binary pair." "AlphaCentauri"b ,"" "It turns out," "Is by far the best star" "In the entire sky" "For searching for low-mass," "Earth-like planets." "But to carry out" "That kind of search requires" "A very dedicated effort." "It's not something" "That you can accomplish" "In a few nights" "With a telescope." "it'shardenoughtoseparate" "The two main stars" "Of Alpha Centauri" "In a space photograph." "Trying to see" "An earth-size planet" "Around one of them" "Is, at the moment, impossible." "The best shot we have" "Is to find the planet" "By the wobble method," "Detecting a star's" "Subtle back-and-forth motion" "Caused by" "The tiny gravitational tug" "Any planet would have on it." "Like time travel," "It seems almost undoable." "theback-and-forthwobble," "That we need to detect" "Is incredibly small." "I'm here at the rose bowl" "And if the rose bowl" "Were the size of Alpha Centauri," "Then the amount of wobble" "That we need to detect" "Is about this much," "About 3.3 inches," "And we need to detect that" "From 4.3 million miles away." "AlphaCentauri"b "" "Is slightly smaller than "a"" "And the planet hunt" "Is concentrated there," "Mostly because a smaller star" "Will show more wobble" "And detection" "Will be that much easier." "In three to five years," "We should have an answer." "Ithinkthatifwewere" "To discover that there's" "An earth-mass planet" "Orbiting the very nearest star," "Then there would be" "A great deal of excitement" "To somehow" "Either build a large telescope" "To try to observe that planet" "Or perhaps in the far future" "To design a mission" "That could actually go there." "withthegoal" "Of our time travel quest" "Identified," "We can imagine our spacecraft" "In earth orbit," "About to leave" "On the first mission" "To Alpha Centauri." "The ship's high speed propels it" "Into time machine mode," "Slowing its clock," "So its passengers approach" "Alpha Centauri" "In three or four weeks," "Seeing things up close" "No human has ever seen before." "First up, a stellar flare" "From the red dwarf," "Proxima Centauri." "On the outskirts" "Of the triple system," "It is the closest" "Of the three to the sun." "proximaCentauriis prone" "To these sudden outbursts" "That can cause it to brighten up" "By a factor of four or five" "Over the course of just a day" "And then fade back" "Just as quickly." "So you might be in" "For some real fireworks" "As you pass by proxima Centauri." "aswecome" "Within the triple star system," "We might imagine swinging" "Past Alpha Centauri "a"" "And using gravity assist" "To send us in a direction" "Of Alpha Centauri "b."" "thesisterearth" "At the ship's destination" "Is the ultimate goal," "And the travelers" "Will be anxious to explore it" "And search for life." "Although the trip has taken" "Little more than a few months" "For the travelers," "The high speed" "Will slow down their clocks" "So much, that when they return," "Nearly a decade" "Will have passed on earth." "The realization" "Of star travel at high speed" "Is a dream for the far future." "On an earth" "Where technology is so advanced" "And changing so fast," "The difference of 8 or 10 years" "Could be dramatic." "This kind of time travel" "May become routine" "To a new generation" "Of star travelers..." "Taking mankind" "On the next giant leap" "In its epic journey through The Universe."