The Universe: Breaking Barriers to Reach Light Speed (S3, E3) | Full Episode | History

streaking through space light is the fastest thing  in the universe it could circle the earth seven   times in one second as it reaches us across vast  distances it reveals the history of the cosmos   we're able to look back in time light travels at  186 000 miles per second its speed is an ultimate   barrier nothing can go faster we have never ever  broken the speed limit but is the answer final   will spaceships ever speed faster than  light is it even worth trying to give   up without trying is just giving up  it can neither be touched nor felt   it is an abstract quantity of immense impact the  rate of motion at the very heart of all existence   the fundamental linchpin of the  universe that we call lightspeed on planet earth where speed is  in demand the fastest people   vehicles and technologies seem to crawl  in a cosmos where light speed is king more than king the speed of light is the  cornerstone on which the universe is built there's   a famous saying in physics which is that the speed  of light is not just a good idea it's the law the speed of light is one of the most  important speed limits in the entire universe the speed of light 186 000 miles per second   is just incredible i mean if  light traveled in a circle around   the earth it could circle the earth seven  times in one second that's an incredible speed that incredible speed is the first thing we  encounter when confronting the phenomenon of light   to say it is fast is a colossal understatement  it's amazing to me that when i talk on my cell   phone i can talk to somebody clear across the  country and i'm not really aware of any time   lag and that signal is going from my phone to a  tower up to a satellite back down and it seems   instantaneous so we really take for granted the  speed of light could practically be infinite to us physics professor clifford johnson of usc  is an avid bike rider circling a track   he considers trying to cover the same 186  000 miles that light does in one second he'll find however that his work will be cut  out for him to travel the distance that light   moves in just one second it would take me 22  months on a bike moving at 12 miles an hour   cycling 24 hours a day but the speed of  light in relation to the speed of life   makes our world work in just the way we've come to  expect one of the beneficial effects for humanity   of having the speed of light be as fast as  it is is that what you see is what you get   lightspeed makes everyday experience  virtually instantaneous when the light   bulb goes on you see it right away anything  that happens around you registers immediately   and certain experiences make it crystal clear  that light travels faster than anything else   including sound one interesting consequence  of the great speed with which light travels   is that you see a flash of lightning essentially  instantaneously but you hear the thunder   only later on but lightspeed has its  limits when stacked up to a place as large   as the universe we think that the speed of  light is unimaginably fast on a human scale   however in astronomical terms  it's actually kind of pokey and so it's ironic that when the  apollo spacecraft blasted into space   traveling at what seemed an amazing 25 000  miles per hour the speed of light proved   frustratingly slow when it came time to talk to  astronauts 236 000 miles away on the lunar surface so when the astronauts were on the moon  and people asked neil armstrong hey neil   what's it like up there several seconds went by  between the question and neil armstrong's answer   email this is houston radio checkover and those several seconds were not because he  was thinking about the answer but rather because   it took 1.3 seconds for the signal  traveling at the speed of light to   reach neil from mission control and  another 1.3 seconds for his reply   using radio waves to come back and  that's 2.6 seconds without even thinking the 1.3 seconds it takes light to travel from  the earth to the moon is pocket change compared   to other celestial bodies light from the sun for  instance takes more than eight minutes to get to   the earth if the sun were to disappear right now  if the sun were to suddenly vanish it would take   eight minutes before we would even feel the shock  wave and see the effects of a disappearing sun the limits of light speed also make communicating  with earth's far flung spacecraft a special   challenge takes up to 44 minutes for signals to  travel back and forth to the probes exploring mars   more than three hours to cassini at saturn   and over 29 hours to voyager 1 the most distant  of all now heading out of the solar system still these distances are  trivial on a cosmic scale   we can almost understand the 10 billion  miles separating earth from voyager but what's next the nearest star is a red dwarf  named proxima centauri nearly 25 trillion miles   away that's 25 followed by 12 zeros i am often  asked a question how can you as astronomer   really comprehend these vast distances these huge  numbers and the answer is i can't the human brain   really doesn't wrap itself around numbers that big  occasionally i actually write out how many zeros   there are in kilometers from here to a galaxy just  to see how huge that number is but in reality of   course as astronomers we would be spending all day  writing zeros unless we came up with a better unit   to use and that's what a light year is a light  year is approximately six trillion miles it's   the distance that light travels in one year using  light years to describe distances opens up another   dimension of lightspeed's character think of  it sirius the brightest star in the sky is 8.6   light years away that means we see it not  as it is today but as it was 8.6 years ago we see the bright star vega as it was 25 years ago   and the red supergiant beetlejuice  as it was 500 years ago it's a wonderful gift of nature that because  it takes time to travel we're able to look   back in time the further out we look in  distance the further back in time we look   we would have no idea what our cosmic history was  if the speed of light traveled instantaneously laura danley is curator of the historic  griffith observatory in los angeles   with light's ability to take us into the  past she's assembled a stack of photos   that tell lightspeed's story of the universe in  snapshots looking back in time to its beginning   more than 13 billion years ago to the present day  i'm putting together a scrapbook of the history of   our family of galaxies and it shows all the  galaxies that we can see with our telescopes   as far back as we can see with our telescopes  each photo in this album then shows something   in the universe with a look back time  equivalent to its distance in light years the famous crab nebula 500 years ago the galactic core center of  the milky way 26 000 years ago and the andromeda galaxy our next  door neighbor 2.5 million years ago   but practically yesterday on a cosmic scale i love this cluster for almost 90 of the look-back  time the album is filled with common galaxies   common yes but intriguingly diverse these two are colliding you can see one going  what appears to be right through the other   and there's a lot of drama in the way galaxies  evolve and the way they interact with one another   so this one would be oh well it's only  about 500 million light years away   as danley places each shot in the album a bigger  picture begins to emerge adult galaxies have   been the main characters evolving in all their  variety for the past 12 billion years but the   cosmos also has its childhood photos showing  galaxies when the universe was a mere toddler these are actually very interesting  galaxies at about 11 billion   light years away these compact galaxies  are represent what might be a two two   or two and a half year old child you  know just really learning how to walk but even these galaxies have  their younger brothers and sisters   this spectacular shot shows a gravity lens a  cluster of galaxies 2.2 billion light years away   that bends light allowing us to  see much further in space and time   the lens reveals a tiny speck identified  as one of the earliest galaxies we can see   as it was 13 billion light years ago  still an infant in the evolving universe galaxies when they were babies  really don't have a lot of   distinguishable features they're kind of blobs  they don't really have a lot of structure the universe as a whole was something of  a blob at the beginning of its life too   what we see of that time are the first light waves  in history reaching us only now 13.7 billion years   after they flashed into existence we see them  in the picture of an afterglow from the big bang and they are known today as the  cosmic microwave background radiation   the cosmic microwave background radiation is the  most distant thing we can see it is in a sense   the picture of the baby upon delivery nasa's  all-sky picture reveals a glow that is uniform   everywhere we can see the universe as it  was in a cosmic moment after its birth   but here our view comes to a sudden halt  what we can see of the universe is limited   not by the size or power of our instruments  but by the barrier of light speed itself how can the fastest thing in the universe  make us blind to the infinity of space knowing that light speed is  6 trillion miles per year   gives us the light year a convenient shorthand for  talking about the huge distances in the universe   but it's just as important to understand  that light speed at 6 trillion miles per year   is an iron clad constant the speed of light  is so constant that the universe actually   changes everything so that you  never see it going any other speed   so the speed of light really is the measuring  stick of the entire universe in fact the constancy   of light speed results in an amazing tool for  measuring distance in the vastness of space the tool is called redshift it happens as light  between galaxies travels at a fixed speed when   the space between the galaxies expands the light  racing between them gets stretched turning red in   color as light goes from one galaxy to another  from a distant galaxy to our own for example   that light gets stretched along with the  stretching of space and that causes intrinsically   short wavelength light like blue light to  gradually become long wavelength or redder light   that fundamentally is the cause of the  redshift that we see in the spectra of galaxies   how does the red shift turn into a way  to measure distance it's all because of   an astonishing discovery made in 1926 at the  mount wilson observatory outside los angeles being up here on mount wilson is always  a thrill for me because it was actually   right here at this location that our  view of the universe entirely changed   it was here that edwin hubble found out the  universe is expanding and that was an amazing   thing he wasn't expecting it nobody thought  that was the case and it changed everything   seeing red shifts everywhere hubble found that  all of the universe's galaxies were moving away   from each other which we now know is caused by the  expansion of space itself as seen from the earth   a galaxy doesn't look like it's moving away but we  know that it is because its light is red shifted a galaxy moving away at low speed has a  slight red shift a galaxy moving faster   has a larger red shift but hubble found  that those faster moving galaxies are also   farther away that meant the greater the  red shift the more distant the galaxy by seeing how fast space is  expanding and working the math   backwards cosmologists have been able  to estimate the age of the universe combine that with light speed and you have  a major brain twister the universe is such   a huge place that the light travel time really  becomes important to us we believe the universe   began about thirteen and a half billion years ago  that means the farthest in any direction we can   look is thirteen and a half billion light years  there hasn't been enough time for light to travel   more than that it's called our light horizon a  sphere 13 and a half billion light years in all   directions containing everything we can see but  that's where the brain twister comes in does space   end there we have no reason to believe that  the distance we can see is the entire size of   the universe in fact it might be much bigger  than that it's just that with light travel   time that's all we can see that's our horizon so  consider this conundrum astronomers in a galaxy   at one edge of our horizon can't possibly see  any galaxies on the other edge of our horizon but they can see galaxies and a half  billion light years in the other direction   and so can astronomers at the edge of their  horizon and on and on perhaps to infinity as for astronomers on earth lightspeed has them  trapped if we ask what is happening beyond our   light horizon uh we have to face the fact that  the speed of light really is a barrier we've never   seen anything beyond our light horizon can we take  comfort in the fact that there is so much to see   inside our horizon this breathtaking shot is the  hubble space telescope's ultra deep field it's   a massively detailed photo of an area of the  sky a hundred times smaller than the full moon   yet containing ten thousand galaxies some whose  light has been speeding toward us for thirteen   billion years beyond that is the cosmic background  radiation from just 400 000 years after the big   bang in nasa's color-coded picture the radiation's  glow is pure green representing a distribution of   matter so uniform its temperature varies no  more than one fifty thousandth of a degree   nothing in human experience is even close to this  kind of uniformity in fact astronomers believe   the universe should really be very different by  rights the universe should be lumpy if you look in   this direction and you look in that direction you  should see two entirely different concentrations   of matter different temperatures but it's  extremely uniform therefore we have a puzzle   the puzzle has its roots at the  universe's birth in the big bang   if everything flew apart from the  beginning why shouldn't it be uniform no kind of an explosion that we know about leads  to that kind of uniformity if you imagine an   ordinary explosion an atomic bomb a piece of  tnt but it's not really uniform at all there's   a piece of shrapnel going off there a piece of  paper going off there an extra piece of iron   going off there it's really very non-uniform so  scientists believe the cosmic background radiation   just shouldn't be as smooth a green as it is we  can find out why in an ordinary paint store let's   consider a universe that consists of different  colored cans of paint in our hypothetical paint   universe we have a can of yellow paint and  a can of blue paint and at the instant of   the big bang in this universe the two cans of  paint start expanding apart from each other in our hypothetical paint universe one side of it  would look yellow and the other side would look   blue but as we've learned the cosmos looks green  whether it's the paint universe or the real thing   the two colors of paint represent the different  particles in the infant universe to end up a   uniform green like the cosmic background radiation  they had to be touching but when scientists   first calculated the speed of the big bang they  concluded that it blew everything apart faster   than the speed of light meaning blue and yellow  were too far apart even at the instant of creation   for any mixing to take place seeing a universe  that's so uniformly green would be very strange   it would be like taking our can of yellow  paint pouring it out and having it be green   then taking the can of blue paint pouring  it out and having it be green as well   it's impossible this horizon problem can be solved  by a theory that i've worked on called inflation   which is a twist on the big bang inflation  is now the widely accepted variation that   makes the big bang work without the  limit imposed by the speed of light   another way this could have happened is that our  paint universe might have expanded only this far the two cans of paint have enough time to  mix and become uniformly green before the   universe undergoes a sudden period of expansion  that occurs faster than the speed of light this would spread green  paint all over the universe if this theory is right the period of inflation is  really the big bang that we observe the other bang   that happened before that becomes really a little  bang that's just a precursor to the real big bang   even today the universe is expanding at high  velocity galaxies speeding away from each   other so fast that they seem to violate  light speed as the ultimate speed limit the faster than light expansion of space sets  yet another limit on what we can see from earth   where the galaxies of the universe  continue to rush away from us   the galaxies that are relatively near  to us those that you can see easily   are moving away pretty fast and indeed the  more distant ones are moving away faster   but the ones that are really far away in fact are  moving away faster than the speed of light and   then there are the galaxies that you will never  see because they started out so far away that the   light from them will never reach you because the  space is expanding faster than the speed of light   space itself then is the exception to the rule  it can expand faster than the speed of light but everything inside it remains bound by albert  einstein and his theory of relativity albert   einstein is the cop on the block you cannot break  the light barrier we physicists can accelerate   particles to 99.9999 percent the speed of light  but we have never ever broken the speed limit   but we don't need to break the limit to  experience the strange province of light speed if the universe bends and  stretches around the speed of light   what happens when we hit the  accelerator and start to get close for most of us light seems simple and  uncomplicated a quality of nature by which we see   the universe under the scrutiny of science however  it becomes strange and bizarre light is such a   common thing in our everyday experience and yet we  have very little understanding of it really it's   very weird the speed of light is something that  the entire universe bends around to accommodate   we can begin to understand why the universe bends  itself around light speed by joining physicist   clifford johnson at a bicycle track where a  tennis ball will compete against a beam of light   if i throw an ordinary object like a tennis ball  i can throw it at a given speed it'll go a certain   distance this is the path of the tennis ball  as johnson throws it while he's standing still   it lands roughly halfway down the track next he'll throw the ball again but this time  from a moving bike with different results if i throw the tennis ball at that  same speed while riding the bike   it'll go faster because it's the speed of  the tennis ball plus the speed of the bike   and so it'll go further compare the  two tosses and the difference is clear   the ball goes faster and farther when thrown  from the moving bike it makes perfect sense   but now we put light to the same test using  the bike's headlight instead of a tennis ball   if i'm standing stationary and i switch on the  headlight of the bike that beam of light that   comes out of the headlight comes out at the speed  of light no other speed but the speed of light   suppose the beam was slow enough for us to  actually see its motion down the track we mark its   position just a brief moment later next johnson  switches on the headlight at writing speed and the   unexpected happens in that same moment of time the  light travels exactly the same distance as before   unlike for the tennis ball you don't add the  speed of the bike to the speed of the light   the speed of light remains the speed of light the  two light beams travel the same distance because   light speed is constant and independent of the  source's motion it may fly against intuition   but it is a fact of nature every beam of light  in the universe travels at the same speed in   empty space no matter how fast the star  or comet or galaxy that emits it is moving after scientists discovered this  fact at the end of the 19th century   albert einstein did the math for the rest of us  and developed his special theory of relativity   with constant light speed as its center understanding the speed of light gave us a window  into understanding the nature of space and time   as we understand now we do not live in a rigid  world where meter sticks and a clock ticking at an   irregular intervals we live in a flexible stretchy  einsteins world relativistic world of space and   time in common experience the universe doesn't  seem very stretchy to us because compared to light   speed we are moving very slowly but when we crank  up the velocity things begin to change as you get   closer and closer to the speed of light all sorts  of strange and marvelous distortions take place   when we say that the universe kind of bends itself  so that the speed of light is always constant   it's amazing how literally that's really true as  you move closer and closer to the speed of light   your time appears to slow down to an  observer that's sort of watching you go by   that's amazing when clifford johnson bikes  around the track he needs to be going about   56 million times faster than his current 12  miles per hour to get close to light speed but suppose he could imagine i'm riding my bike  close to the speed of light never mind whether   that's possible or not just imagine that this  was happening my clock's running slow compared   to the cameraman on the ground who's filming  me if i do that for a while i'm going to age   much more slowly than the cameraman who's on  the ground so that when i come back from the   trip and come back and talk to the cameraman  he's actually much older than when i left him   if this sounds like magic instead of science there  is proof in something that many of us experience   every day a great example of einstein's special  theory of relativity and the fact that clocks   that are moving relative to you run more  slowly than your own clock which is at rest   is the gps system the global positioning system  lets us drive our cars without getting lost gps begins with a network of 24 satellites  orbiting the earth 12 500 miles above the surface   at any one time the device in your car  receives signals from at least four satellites   and compares their light speed travel times to  calculate an accurate location on the ground   drive 500 feet then turn right the whole  thing depends on super accurate clocks   when the engineers designed the system they knew  the satellites would be orbiting at nearly 7 000   miles an hour the speed is enough to slow down  their clocks by a tiny fraction of a second   the engineers have factored all the  relativistic time differences into the system   which gives it impressive precision if the clocks  in the satellites are running at a different rate   than the clocks down here on earth and you don't  take that into account you will get the wrong   answer for where your car is drive point one miles  to destination on left the distortion of time is   only one of the strange results of traveling close  to the speed of light on the bike track clifford   johnson continues to push the envelope as space  begins doing odd things to him and his bicycle imagine i'm on my bike again  going close to the speed of light   an observer looking at me would  actually see for example that   the length of my bike in the direction  of motion and moving is getting shrunk   actually the bike is getting shorter the effect is  called length contraction and together with time   dilation it is seen by a stationary observer while  looking at someone traveling close to light speed but professor johnson does get his own  chance to witness lightspeed's weird effects   as his velocity closes in on light speed  his view of the world changes drastically   what i'm seeing as i move closer to the speed  of light straight ahead is that the shapes   in front of me are getting quite distorted as  compared to everyday life everything is being   twisted into a sort of tunnel shape and the colors  are getting distorted in various ways the color   changes come from the doppler effect and the shape  distortions from a phenomenon known as aberration   the distortion is somewhat similar to what you  would see if you were driving through a rainstorm   if you were stationary you would just see the rain  coming straight down if you looked out of the side   of the window whereas if you were moving through  the storm you would see that the rain appears   to be slanting towards you as a result of your  motion and that's at the basis of that warping   effect that you get as you're moving near the  speed of light towards objects in front of you in reality we don't have to travel near the speed   of light to experience the distortions  caused by motion through time and space they are with us every minute of the day   all of the distortions that happen as a result  of a finite speed of light still happen on an   everyday basis even in our everyday life but the  effects are so tiny that we can't perceive them   still lightspeed has its other quirks in the  slow-moving world quirks we perceive very well   the speed of light may be a constant  but only in the vacuum of space   when light moves through  things like glass or fluids   it slows down appreciably if it didn't  things like telescopes and human vision   would be impossible but what would happen if light  slowed down much more if the speed of light were zero light speed is 186 000 miles per second it is a  universal constant but a constant with a catch   it travels at that speed only in a vacuum  light changes its speed when it travels   through different media it travels more  slowly through water that's why you see   refraction and bending and rippling of light  when you're underwater life as we know it would   be very different if light didn't propagate at  different speeds through different materials   for example we wouldn't be able to see  our eyes wouldn't work the same way   in a universe where light moved at  the same speed through all materials   we would know little of the world around us  seeing only vague blobs of dark and light   that's because our eyes depend on biological  lenses to focus images on our retinas just like   lenses made of glass they work because light slows  down as it passes through them why is that because   light is absorbed by the atoms of glass and then  they re-radiate it later so there's a delay factor   light hits an atom the atom vibrates and then  sends a light package off so there's a delay   factor the delay factor also causes light to  bend when it hits glass shaped into a lens   bent in just the right way light can be focused  collected and magnified for astronomers studying   the universe nothing could be more important  thank goodness light slows down when it goes   through glass because that's the reason why we  have telescopes the reason why we have telescopes   is because light bends going through glass and  we can concentrate concentrate large amounts of   light to a single point and then that gives us the  ability to see the marbles in the universe itself   light travels through the glass lenses of  telescopes at about 124 000 miles per second   two-thirds of its speed through a vacuum but some  scientists are looking at making use of light at   far slower speeds and then we have the aos over  here they're pretty much all functioning now   at her lab on the campus of harvard university  dr lena howe has taken slow light to the extreme   by reducing light speed to zero the speed of  light of course is uh incredibly high i mean   nothing goes faster than light and you know the  usual 186 000 miles per second and we kind of   thought gee that's awfully high let's let's try  to do something about it so we have a detector   right there howe and her team conducted their  experiments in a complex laboratory filled with   lasers mirrors prisms and other exotic gear it is  a branch of physics where few have dared to tread   if you can start to change things so  dramatically as taking this enormous light speed   and then bring it down to bicycle speed that  then you're in a completely new regime of nature   you were able to now start to probe areas regions  of nature where nobody has ever been there before   the brakes are put on lightspeed inside  howe's lab by focusing lasers on two   microscopic clouds of sodium gas chilled to a  few billionths of a degree above absolute zero a control laser hitting the two clouds sets them  up for action then a quick light pulse shoots   into the first cloud where it is squeezed into  the gas and slowed to just a few miles per hour   the light pulse goes from being about one  kilometer long in free space it compresses   like a concertina as it enters the atom cloud and  ends up being only 0.02 millimeter in size that's   less than half the thickness over here so  really small and it's so small that the light   pulse actually ends up fitting totally inside  the atom cloud haus says the atomic imprint   of light in the sodium cloud is a perfect copy  embedded in atoms of the original light pulse it can then be stopped in free  space between the two clouds   before moving on when it enters the second  cloud another shot of the control laser   expands it to its original size shape  and speed of 186 000 miles per second   it is comparable in some ways to a science fiction  transporter that sends people or objects through   space so in this experiment what we really do  is we stop and extinguish the light pulse in   one part of space and revive it in a completely  different part of space and set it back on its way since light can carry information this  super advanced technology points the   way to futuristic light based computers  that bypass wires and electronic chips information read directly from light may  be faster more compact and more secure than   anything we have today but the greatest vision  of scientists and dreamers is to be found at the   other end of the light speed spectrum we still  face the speed of light as an impenetrable wall   a speed that dr einstein told  us could never be exceeded   yet history is packed with impossibles that have  become realities will we ever for instance be   able to reach the stars and ships that go  faster than the speed of light if so when in april 2008 world-famous  physicist stephen hawking   called on the human race to colonize space  and make interstellar travel a long-term aim   spreading out into space it will completely change  the future of the human race but may be determined   whether we have any future at all the stars  are so far away that interstellar travel is   impractical unless we can go faster than light  speed but that's an obstacle einstein's theory   of relativity tells us that a spaceship's mass  approaches infinity as it nears the speed of light   so as you try to go faster and faster and faster  you actually get to a point where it takes   more and more energy until it's an infinite  amount of energy to go the speed of light   that's impossible it means the travel at  light speed is also impossible or is it mark millis is one of a handful of scientists who  isn't ready to throw in the towel on the subject   a nasa propulsion physicist by profession he likes  to build models of starships in his spare time   and is well aware of the giggle factor  in any talk outside science fiction   of star travel the giggle factor is actually  a healthy response it helps provide skepticism   to the topic to ask deep questions to  make sure that we're proceeding correctly   once head of nasa's mothballed  breakthrough propulsion project   millis is editor of a book that has collected  the serious current research on the subject   when it comes just to the light speed  issue there's about three dozen physicists   who've written articles some skeptical  some suggesting new methods on the topic   one is saying that anytime soon we'll be  able to have warped tribe to the stars   but on a scale of centuries to  millennia it can't be ruled out   virtually all physicists agree it's impossible to  travel through space at faster than light speed but there may be a way to cheat by altering space  instead of traveling through it believe it or not   even nasa scientists are studying the possibility  that perhaps we can fold space punch a hole   in space make a subway system through space  and time that's the basic idea behind using   wormholes to actually twist space around on  itself and take a shortcut through the universe what would a wormhole machine look like  probably huge in scale with equipment   staged perhaps on a massive number of  asteroids arranged in a gigantic sphere it would require an enormous battery of laser  beams to concentrate tremendous energy to a single   point you have to attain fantastic temperatures  the highest energy attainable in our universe   in order to open up a hole a bubble  a gateway perhaps to another universe another way of tricking space into letting  us travel faster than light is the warp   drive miguel alcubierre was the first one to  write about the warp drive in 1994 alcubierre   a mexican physicist worked out the math for a  starship propelled by warping space-time itself behind the ship space-time is expanded  in front of the ship space-time contracts   in between the ship rides like a surfer  the ship itself sits inside a bubble   and the space around it  pushes it faster than light   a successful warp drive if it is possible  at all is probably centuries away but in switzerland physicists at the large hadron  collider may be headed in the right direction   right now now the large hadron collider is an atom  smasher it's a particle collider but it's going   to get to high enough energies that space and  time will actually warp and bend we're actually   practicing how to bend space in the laboratory  it's the first baby step toward a warp drive   with the physics we now know we won't travel  faster than light speed in the foreseeable future   that doesn't mean we shouldn't try even  though light speed travel might turn out   to be impossible to give up without trying is  just giving up outside his work at nasa millis   has founded the non-profit tau zero foundation  to encourage serious research on star travel although few scientists are pursuing the  idea actively many agree it's worth at least   the effort understanding our  universe is one of the most   basic needs human beings have  as an intelligent species   so should we pursue technologies or physics that  might allow us someday to travel faster than light   absolutely because we never know where this might  take us even though we might never discover a way   to travel faster than light we might discover  a whole bunch of other very useful things   and what if science ultimately proves the light  speed barrier is unbreakable and star travel is   impossible it would put a whole new perspective on  spaceship earth forcing us to use our technology   to treat it well as we remain its passengers  on our continuing journey through the universe you

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Length: 44min 28sec (2668 seconds)

Published: Mon Mar 01 2021