Can We Travel Faster Than Light? with Dr. Miguel Alcubierre

can we achieve faster-than-light trouble that's the big question isn't it it is important though throughout the history of sci-fi it's been explored many times but usually never backed up as to how it could happen that was usually glanced over and faster than light travel is something we want warping it many times the speed of light to explore our entire universes and the lowering idea especially if we want to someday meet intelligent alien life it's infectious even so how do we do that speaking in terms of the real universe unfortunately there have never been very many ways to do it according to known physics in fact it's almost hostile to the idea breaking the speed of light within Einstein's relativity the best description of the universe at large that we have would require infinite energy infinite energy isn't possible or is there another way is there a way to essentially hack the universe and move its speed so fast that science fiction generally didn't imagine until science itself actually did my guest today explored just such a concept after watching an episode of Star Trek and thinking about how a warp field could be established that would allow faster than light travel it's just an idea consistent with relativity there's no guarantee it would actually work but it's one that so far has stood the test of time people still wonder about this idea over 20 years after its formulation as I said it's consistent with relativity but with caveats pretty big ones but it's important to explore the idea nonetheless after all if we respond to all ideas as inherently impossible we'd have never gotten very far as a civilization so can we actually travel faster than light [Music] [Applause] [Music] welcome to event horizon with John Michael Gautier [Music] [Music] joining John in this episode is theoretical physicist dr. Miguel Alcubierre dr. Alcubierre received his PhD in 1994 through the study of numerical general relativity and has since worked at the Max Planck Institute for gravitational physics in Potsdam Germany and the National Autonomous University of Mexico dr. Alcubierre is best known for his 1994 paper the warp drive hyper first travel within general relativity where he describes his theory for traveling faster than light with what's become known that's the Alcubierre warp drive welcome everyone to event horizon with me John Michael Gautier if you enjoy what you hear fall into the event horizon hit the like button and become an active subscriber by ringing the bell Miguel Alcubierre welcome to the program hello Doctor everybody knows you for your warp bubble concept but you've done a lot of science that was 1994 you've done a lot of science since then what does your work focus on these days well and these days have been working on black hole formation and also on something a little bit esoteric that we call boson stars which is a model for a start made made of a special kind of field that could mimic a black hole in many circumstances so I've been specializing in that area and my work is mostly numerical simulations so for a long time I've been doing numerical simulations of black holes base times formation of black holes collapse of stars and also gravitational waves production of gravitational waves so that's that's my main work and I've been working on that for the last 20 odd years we recently detected with the LIGO experiment the formation of or the coalescing of two neutron stars and I suppose that would be even more applicable to black holes if you have a binary black hole that's merging now do you study that I've studied binary black hole formation collisional pioneer black cause not so much neutron stars neutron stars are difficult for different reasons because they have a lot of matter and you have to deploy dynamics and maybe magnetic fields and things like that black holes are cleaner and I've been studying black holes or long time so during the 90s and even early part of the 2000s my main work was black hole simulation simulations of black holes that collide in an inspiring they're orbiting and that they to an in spiral condition and that was actually the first thing detected by LIGO three years ago they detected the first gravitational wave detection ever was a collision of two black holes which is exactly the problem I have been working for a long time now when when black holes merge collide like that how long does that process take before they become entangled and gravitationally and they actually collide depends very much on how they formed but it could take tens of millions of years it's a very very long process it's very slow they approach each other very slowly because they're emitting very low gravitational waves energy they're losing energy gravitational waves but it's very very slow and those gravitational waves in principle cannot be detected because they're extremely weak but this process takes millions and millions of years but eventually they get to the point in which are very very close and they're they're separated just by by a few times their own radius and at that point the whole process can take just fractions of a second and that's what we detect so that the final the detection of gravitational waves from a black hole collision typically only detects the less than a second the last fraction of a second of a collision that's what we can detect and the first detection actually the whole thing lasted for about twenty twenty day parts of a second so you're 124 seconds or something like that it was really very very close neutron stars actually take longer so when two neutron stars collide we can detect the last minute or so of a collision and that's because they're usually closer by so the signal is stronger and it's also more in the range of the detector so we can detect for longer but black holes is a very very fast process what we can detect some when you have two incredibly dense objects like two black holes or two neutron stars for that matter this has to be a ridiculously abnormal environment do you see things like so you create gravitational waves but what what are the radiation comes out of that do you see like this perhaps a solution to something like fast radio bursts where you you just see this mysterious burst of radiation that comes out of nowhere could that be from these kinds of mergers yes that's exactly what we think not from black holes went to black holes merged and nothing else happens it's only gravitational waves because black holes are vacuum they have no matter the matter has all been concentrated in the center and the center is beyond the horizon sir cannot nothing in that happens inside the black hole can affects us and no radiation comes out from there so when two black holes collide all you get is gravitational waves well when do two neutron stars collide that's very different because neutrons are made of matter they're made of fluids and they have magnetic fields and etc so when two neutron stars collide essentially you get fireworks you get a huge explosion and and this explosion produces radiation in all wavelengths and in principle yes we believe that part of the gamma ray bursts that have been detected for the last 20 or 30 years by satellites come from collisions of neutron stars there are two different types of gamma-ray bursts what we call the long-lived and the short-lived and we believe that the short-lived are mainly caused by collisions of neutron stars the long-lived we still not sure but the short leads are probably almost always the collision of two neutron stars and this is extremely interesting because if we can get the information from the collision of the neutron stars with gravitational waves and also we can detect them also with gamma rays and other things then we can learn a lot about the system we can even do cosmology so these types of systems are far more interesting at the moment there's only one confirmed detection of a collision of two neutron stars from LIGO from gravitational waves that was just a very year ago a year and a half ago and there hasn't been another announced but maybe they they've seen something in the last few weeks and they're a bit cautious about announcing it but there might be some hints about it but that those are the extremely interesting systems collisions of stars gives us a lot more information about the universe now is that due to the fact that nothing can escape a black hole's event horizon so if you have two black holes coalescing and falling into each other and becoming a single black hole you can't get anything except gravitational waves because nothing can escape the black holes so you can't get any kind of radiation other than I guess some maybe some kind of Hawking radiation off it so is that the case that that they're just simply that's exactly the case when two black holes collide there's nothing else there's just two black holes there's nothing can escape from inside the black holes so there's no light there's no radiation of any kind the only thing you get are gravitational waves so in essence is a very clean system but it's also you can only detect it on gravitational waves and and nothing else even even the Hawking radiation Hawking radiation is a concept that it's theoretically very well understood but we've never seen evidence of that because for a black hole the size of a star or bigger which is the ones we've seen the Hawking radiation is is completely negligible with its kind just being north completely there's no hope of detecting it so what you detect is just the gravitational waves coming from the collision still that's very interesting that was the first system we've seen we saw and we've seen about ten maybe a lot more now because libels are already taking data again but until the beginning of this year we've seen about ten collisions of black holes with wood like when I'm when I say scene I actually mean absurd with gravitational waves not with light but so that happens sufficiently often that we see them a lot collisions from nutri stars are not that easy to see because if they happen very far away you can't see them because the signal is very weak they have to happen very close by so you might be able to detect them but knuckles you can detect very far away because they're usually bigger and that means that the signalling gravitational waves is much stronger but that's all you get so you get the gravitational wave you know it was two black holes you can you can measure the distance because of the gravitational waves and you can get the mass of the black holes and maybe if we're lucky even how fast they were rotating but it's very difficult to know exactly where they were so we cannot pinpoint the galaxies in which the black holes collided because there's no light coming out of the system and the gravitational wave doesn't allow you to locate this in this in space very well so you can sort of say it's came from that region in space but we don't know exactly where whereas when neutron star is much more because if you see the light then you can pinpoint the galaxy exactly what would the Hawking radiation of a black hole look like would it be gamma rays well yeah Hawking radiation is as I mentioned is a theoretical idea that came from Hawking in the 70s it he still has not been confirmed observational or experimental II but basically Hawking radiation is just what we call blackbody radiation now a blackbody is not the same as a black hole a black body is just physicists terms of saying something hot so we call it a black body because it absorbs everything of all sins do it but and then emits the light packets as just heat so the Sun even though it's not black it's yellow but it's a very good approximation to a blackbody in in physics terms it's just something that emits light because of its hot it is hot and depending on how hot it is it emits light in different wavelengths so if it's not very hot you can't see it if it's a little bit hotter you see it red and hotter still than yellow and if it's very hot you see it blue now black holes emit radiation just like this a blackbody radiation but the temperature of a black hole is inverse to its mass that means that very large black holes are essentially very cold and emits very little radiation and radiation it you cannot see with normal light it would come in radio waves so for a black hole the mass of a star the Hawking radiation would come in the very very far radio waves and it would be so weak that we wouldn't be able to detect it at all if the black hole was very small and when I mean very small about the size of an atom or something like that I mean really small and with the mass of a few atoms then it would emit radiation very very hot and it would come out in memories probably but we haven't seen that it's it's very difficult to detect so so there's no proof yet observation or proof that Hawking radiation exists is just a theoretical idea now to get into the concept of a star Drive that you could use a black hole to drive the smaller the black hole the more radiation it emits right yes that's correct so if you if you saw I mean could there be like a techno signature there as they say with in astrobiology a technic would an artificial very small black hole low-mass yeah would that be visible there's something that you could say that is an alien starter I've driven by a micro black hole not really because the process would be very there it's very fast though a very small black hole with a Mitch Hawking radiation so fast that it would evaporate very quickly and what you would see essentially is probably something more like an explosion a burst of gamma rays so some people have actually speculated the gamma ray bursts are actually black holes evaporating but the idea doesn't fit very well but you will see some sort of bursts of radiation and that's it it would die very quickly because the black hole as it evaporates as it emits radiation it loses mass and the smaller it is the faster this goes so very small black hole would evaporate very quickly in a matter of seconds so you wouldn't see something that just emitting Hawking radiation for a long time you would see a burst of radiation and then it's dead right it would be something very quick and and and also it depends on the size if you have a small black hole that's still a few grams in weight that would still not emit enough Hawking radiation for us so detected it would have to be something that weighs not much more than a few atoms and then you would see a lot of radiation and it would happen very quickly so you would see it as burst but so say you had a googol it's essentially a tiny little black hole that you've artificially created with lasers it would Brady it in a certain way but very rapidly if I'm understanding you correctly so you would you would see it evaporate almost instantly exactly yeah now you're also known for the Alcubierre warp field and I call it the work field because you know a lot of people say stardrive but it's really the idea of warping space-time and it's at its most basic what is the Alcubierre warp field well the idea is just a way in which you can deform space that would allow you to travel in principle as fast as you want in space without actually moving so it's it says you've mentioned it correctly it's not a star drive it's not a machine it has nothing to do with a spaceship it's just a model of what you would need to do to space to be able to move very fast and the idea is to use the fact that space can be deformed and according to the theory of relativity Einstein's general relativity gravity is just at the formation of space it's at the formation of the of the geometry of space so space can be curved usually people here talk about the curvature of space or space-time but a curvature is a very generic names that you can do many things to space you can expand it and you can contract it for example and we've all heard about the expansion of the universe and that happens because space is expanding so people usually don't understand that correctly because they think that if space the expansion of the universe they think is because galaxies are flying apart because there was some huge explosion somewhere but it's not like that at all I mean galaxies not flying apart elastics are just sitting there quietly in their own corner of the universe but space between them is expanding it's been stretched so you can do that to space you can stretch space and you can also contract space and then the ID I have back in 94 was that you can do this in a very small scale so if you imagine that you do a very violent but very localized expansion of space behind you that would push you away from things that are behind you and if at the same time you do an opposite contraction of space in front of you that would pull you towards things in front of you and the net effect of those two things combined is that you would move you would move through space you would get away from the things behind you and closer to the things in front of you but you will not be moving yourself you would be sitting in a bubble of quiet space if you want with a violent expansion behind you and a violent contraction in front of you and that would apparently you would move through space without moving out so it would space doing the moving and this is the idea I had this I called it the warp drive because it gave me the similar idea to what happened in science fiction but it's this idea of a warping space to be able to move fast very fast and there's no limit to how fast space can expand or contract so in principle you could use this sort of warp bubble to move faster than light so that was the idea I had in 94 now there's a price to pay and there's nothing is free so the theory of relativity tells you that curvature or this geometry of space-time can be the firm deformed but it's deformed through them the effect of gravity so you need large container concentrations of mass and energy to produce at the formation of space and there's some equations we call them the Einstein field equations that tell you if you have this concentration of matter you will produce this deformation of space and that's the normal way in which we go about it we we think ok we have a star and the star has this concentration of mass and we go through the equations and figure out what the formation of space related to the star is and then that gives us the gravitational field of the star but in this case I did it the other way around I said I want this very specific deformation of space this warp bubble and you go through the equations backwards and it tells you what sort of energy density or what sort of mass distribution you need it to be able to produce this strange deformation of space and when you do that you find that it's something very nasty because you need something with physicists called negative energy which maybe doesn't say much to ordinary people but if people remember this famous equation e equals mc-squared that tells you energy and mass are the same thing then when we talk about negative energy we're really talking about negative mass and negative mass as far as we understand does not exist in the universe so that's a big problem with the word friend you need negative energy and even if you have negative energy you need huge amounts of negative energy because to the wrong the space is very difficult to deform space it doesn't like to be deformed so in order to deform space a lot you need huge concentration system of mass you need planets entire planets of energy to be able to deform space even a little bit so you will need for the work type the equivalent of a Jupiter sized object but on pure energy and also if the energy would have to be negative not positive so that's that's a big problem with the world right but the idea was just just this basic idea that you can actually the for space and it would allow you to travel faster than light if you deform it in the right way the idea of the of the warp bubble and warp drive what inspired you to think about this was a science fiction as in Star Trek yeah I was actually watching an episode of Star Trek The Next Generation I don't remember which episode it was but it was some episode of Star Trek The Next Generation sometime in 90 - I was doing my PhD at the time in Britain and watching this episode they they keep always talking about the warp drive and the Wardrobe and and I was doing a PhD in the black holes at the time and black hole collisions precisely and I was using a theory of relativity all the time so I started thinking how maybe did they talk about the warp drive they mean that they were deforming space so how could you really deform space to be able to do something similar to what they do in science fiction and I started thinking about that and then I had this idea of the expansion and contraction of space the expansion behind you the construction and from in front this sort of bubble and then I went back to the office and I did some with calculations to see if the idea could be expressed mathematically in a simple way and I found that it yes you could express it mathematically in a relatively simple way so I did it and then eventually I published a paper about that I actually I was doing my PhD at the time so I was still a student I went to my supervisor to tell him of that the idea and I had already written something up and I was afraid he would tell me to just stop thinking idiotic ideas and go back to work but he was actually very supportive he told me that it was a very nice idea and he helped me publish it so was actually my first scientific paper and on that note we have to go to break be sure to LIKE subscribe and hit the bell for this channel if you like interviews like this and we will be back in a moment and we'll talk much more extensively about the idea of a warp bubble if you'd like to support event horizon you'll be pleased to know we've recently launched a patreon link in the description below or alternatively you can use your cellular telephone to scan the assemblage of squares on screen now be sure to LIKE subscribe and share the video and now back to John and we're back with dr. Miguel Alcubierre dr. you were inspired by Star Trek 2 which is something that that I think is important because science fiction tends to inspire the imagination for anybody from scientists down to the common person you were inspired into thinking about could you create a warp-field now yeah tell us more about this warp field where you could create a geometry I suppose of space-time where you have one area of space-time in front of the ship and the ship is stationary within a piece of space-time essentially broken off from the rest of of space-time so how does it work is it less dense in front of the ship and more dense behind the ship how does this work well it's it's not so much density is this a dynamic thing it's a space kind contract and it can expand so in front of the ship you would have a region in which space is contracting very violently and very quickly and behind it you would have a region an opposite region in which is expanding very very and very quickly and it would do this in in a fin shell so the idea is that you would have a sort of relatively large region of space in which space is quiet and nothing is happening it to it and and you're sitting inside is this region and then on the boundary of this region you have a very thin shell in which there's either expansion behind you or contraction in front of you and this is a very violent effect so you would it can move you very fast so that's the basic idea and this is when we think about a field here we're talking about really what's really the gravitational field it's the gravitational field is the geometry of space-time that's how we understand it so it's it's the gravitational field the one that's producing this now you can think about an another kind of field or energy field or something that's the one the producing this because if you want to deform space you need some concentration of energy or mass so the easiest thing is to think that it's not so much mass that you're carrying around with your negative mass is some sort of energy field that you're projecting and this energy field has a very large negative energy and this produces this strange curvature of strange expansion and contraction of space in front and behind you so that's the basic idea I never went very much or very far into the details I just wanted to show that this was in principle possible that the questions of general relativity allowed for the formation of space that looked like this and I also showed very quickly that you would need these negative energy which is a big drawback because as far as we understand we don't have it in the universe so that's that's basically how I how I left it and and then I never worked back on the on that again so a lot of people have worked on that in the past 25 years but I never went back I I only wrote the first paper and then I've been just looking about what people say about it you introduced an idea and saw what happened exactly so because of mass energy equivalence if if you see and you have evidence of negative energy which maybe there is a little bit of evidence for that there's certainly nothing for meit negative mass but is there any evidence that we could create such a material negative negative energy might be possible in small regions of space and any very small quantities I'm not sure if that would be useful for the warp drive because one thing is it may be it's possible but maybe you can't control it very well and maybe it's very a very small quantity and you need huge amounts of it but still it's it's possible that negative energy is we have hints about it quantum theory tells us that in some circumstances something that like negative energy happens for example a very classic example that comes from about 50 years ago it's something that comes from quantum mechanics quantum field theory and it's actually called the Casimir effect and the Casimir effect the idea is you put two parallel metallic plates very close to each other and the metallic plates conduct electricity and that means that even if they're not charged they produce some sort of boundary conditions for the electric field and because they're conductive so inside between the plates then you can only have a very definite number of modes of the electric field those that fit in there's like a string if you have a string and a guitar can only oscillate in a given certain ways because of the length of the string so this is the same idea that the separation of the plates makes the the electric field in the middle allows you to only to oscillate in very specific ways and outside of those plates the electric field can oscillate any way it wants because there's no no's restriction and we know that according to quantum theory the vacuum is not empty so that means that the vacuum is actually full of fields popping in and out distance all the time we called out the vacuum energy or the vacuum the quantum vacuum or the vacuum energy and it since it outside you have have more freedom than inside the plates that means that inside the plates you have less vacuum energy than outside and if you define the vacuum energy outside of zero then it means that inside the plates you have negative energy because it's less than zero so that's an effect that we've been we've known for about 50 years it's a completely theoretical idea it hasn't been measured not the energy there's a secondary effect that all these things would imply that the plates feel a small amount of force and there will be a force that would try to put them together to bring them together this is called the Casimir force and I understand that the Casimir force has been measured it's very difficult experiment but apparently the Casimir force has been measured but the this negative energy inside has not been measured now if it does exist and it probably does it would be a very small amount of negative energy so it's not enough for a walk right by far and and even then it's not clear how you can manipulate that so it's very little and not very easy to manipulate so I'm not sure that would help but there's this hints that maybe in some cases negative energy exists then we also know in a separate casing which is not so much negative energy but there's something like anti-gravity going on around in the universe and maybe anti-gravity could also be used for the warp drive it's not clear at the moment but maybe we could and when I talk about anti-gravity is the ID we normally think of gravity as a force that brings things together that planets attract each other and objects attract each other because of gravity and the gravity would be a repulsive form of gravity that would make things repel each other and this might exist because we've seen in the universe at large for the last 20 just over 20 years we've realized that the expansion of the universe is accelerating instead of decelerating it's going faster and faster all the time and the only way in which we can understand this is specify postulating some sort of anti-gravity in the universe at large we normally call it dark energy so if you hear about dark energy when people talk about the universe is this mysterious form of energy and energy field that produces a little bit of anti-gravity that causes the expansion of the universe to accelerate and this antigravity might be useful for the world trap I'm not sure I've tried to do some calculations in the past but I've never been able to go very far but my hope is that yes maybe a dark energy could be used to do something similar to a warp drive at some point in the future but but still not clear at this point so because of mass energy equivalence Einstein's famous equation e equals MC squared if you can find some sort of negative energy whether it's dark energy or or Casimir effect or what-have-you does that suggest that you could create and actually perhaps manufacture negative mass at you know an object that has negative mass yeah it's a good point and one what might think that it's possible I don't think it's very likely because when we think about mass as such we're actually thinking of on particles elementary particles we have no hints that thus any elementary particle with negative mass in this case would when we think about negative energy would be more like a an energy field and instant the energy would not somewhat much be negative per se but just less than the vacuum and the vacuum if we define the vacuum as zero then it would be negative but it would be more like that like less than the vacuum and and it's difficult to see how you can translate that into a particle and make a particle negative mass so even though it might be suggested by the formula a equals MC squared I think in practice there's probably not not that easy or not true at all and that you could create a particle of negative mass but it's true that nothing forbids it and in the in in the physical laws we know there's no nothing that forbids to have a negative mass particle it's just it would do very strange things and we have never seen something like that in other words the the universe does not ban the existence of something with negative mass so you have a an apple made of negative mass that would be anti-gravity the universe doesn't forbid it but that doesn't mean it can exist right so yeah it's not so much the universe doesn't forbid it is the loss of physics as we understand them today don't forbid it it might be very well that the universe does forbid them but we just don't know how so is the loss we understand does not forbid it but there's no indication that that's something that can happen right it's yeah it's not same so there's things that are not forbidden by the laws of nature but don't happen for example the laws of nature are the laws of mechanics Newtonian mechanics are reversible so in principle if it can break a glass in the floor the loss of mechanics would allow the process to be reversed so all the piece of glass to jump together and coalesce into a form form glass and jump into my hand that's allowed by the laws of physics but it doesn't happen right because it's violate all the things like thermodynamics and things like that so it's just statistically not not not likely to happen so it might be something like that that the laws of physics do not forbid negative mass but maybe it's again statistically unlikely in the same way as as a glass reconstruction itself would be unlikely right so very very unlikely say let's conjecture for a moment say that it could exist is there a way for the Big Bang to have produced matter with negative mass if they do exist them they should have been produced in the Big Bang the the Big Bang there was so much energy around that essentially any particle that could exist was created most of those particles don't live very long or so that would be another question right you have a negative mass particle how long does it live so most most elementary particles we know about are actually unstable and they decay very quickly and to other other types of particles and in the end were only left were a few stable particles it's the ones we were taught about in high school right that possibly the the proton the neutron and the electron and everything is made of those three because those are the only three that are actually survived because they're stable all the other zoo of particles that we know from particle physics are unstable but they're all produced at the Big Bang because at the Big Bang there was so much energy available available that everything was pretty everything that could be produced was produced so yes if it's negative energy particles can't exist and in principle it could be have been produced in the Big Bang but the next question would be how long do they live if they don't live very long we wouldn't see them around and it would be interesting if there was some sort of stable negative energy product well but then we would have seen it that that's what would respect right if there's some sort of stable particle then we should see you today because since it's stable it should be around we should be able to detect it right and we haven't been able to detect anything like that so if they do exist they're probably not stable now that's somewhat of a mystery in and of itself within within physics is if the Big Bang created antimatter then shouldn't we see ant of what happened to all the antimatter it should have been almost equivalent amount to normal matter but yet we don't see it leading to questions about is this yeah did did most of the universe annihilate you know as far as matter goes early on in the universe that's an excellent question it's one of the biggest puzzles and mysteries of modern physics that we don't know the answer to hundred and and we're certainly worried about that so yes in the big bank as far as we understand physics today an equal amount of particles and anti particles should have been produced and then then those particles should have annihilated at each other when they found each other when a particle and antiparticle meet they annihilate each other and they produce pure energy so we should live in a universe of pure energy because all the particles and antiparticles should have annihilated each other and should have been exactly equal amounts of them because of the symmetry and of course that's not the case fortunately we're around on this matter around so for some reason they must have been at the beginning as a slightly larger amount of matter than antimatter may be a very small fraction but a little bit more matter than antimatter and when the annihilation occurred some matter was left behind we don't really know why that's a big question people have been thinking about that for 50 years at least if famous physicists in even Soviet physicists like ammo and things like we're thinking about why matter prevails over antimatter and people are still thinking about that today but we don't have a clear answer yet but it is one of the big mysteries of modern to ethical physics why there is there's matter and no one time matter around back to matter with negative mass how would this stuff behave it would be by its nature anti-gravity so if you were looking for it in nature would it immediately eject itself out of a galaxy or would it concentrate at certain points in a galaxy where you have this this gravitational equilibrium going or would it be out in the intergalactic space just once it would produce a different type of gravity so a large a large object made of negative mass would produce a gravitational field that would be repulsive so if you were so instead of falling into a lot so imagine you have a star like the Sun but it's made of negative mass so instead of falling into it it would be propelled by it you would fly away from it because it the field it produces is opposite so it would produce producer repulsive field now as far as small particles that that's not true because a small particle it doesn't matter that's one of the things we know about gravity that the trajectory of a small particle when it's moving in a gravitational field of a much larger object the trajectory follows is independent of its mass so it doesn't matter the mass is positive or negative or just it will do the same thing so if we have the Sun and the Sun is normal the normal star of positive matter and we have an earth made of negative mass it would still go around the Sun exactly the same way the earth goes around the Sun because the mass is much smaller and doesn't matter if it's negative or positive it would follow the gravitational field of the Sun and that's attractive so it's more like that it large amounts of negative mass would produce a repulsive gravitational field but a negative mass particle would not be repelled by the Sun it would still be attracted by the Sun because it doesn't matter which times the mass is so yes smoke particles of negative mass would not be expelled from the galaxy but if they clump together into a larger object that object would be repulsive things would fly away from that object now with this concept of negative matter I suppose you could call it this is also important with things like creating stable wormholes and and yeah essentially any speculative way we can conquer this beautiful hype so to speak now the universe doesn't ban it but we have no indication of it how could we detect such matter at which I guess would be the first step in to harness its power how could we detect this negative mass material if it existed at the distance it would be difficult you would have to find some sort of objects large very large object in space that instead of attracting nearby objects repels them so but if there was a galaxy with negative mass then we would have seen it because we would see that the trajectories of other galaxies close to it our pulse if instead of attractive so maybe we would should be able to see it in large clusters of galaxies and if there was a galaxy there with negative mass if if the object is much smaller then it's very difficult to detect if you have individual particles with negative mass then we should see those in particle accelerators and then we would should be able to measure it because essentially energy is conserved so in an interaction with maths with particles a negative mass you would see that you gain more energy than you put in because some of the energy became negative and you ended up with negative energy particles so that you should be able to measure that in the energy balance and in particle collisions in an accelerator so that we would have seen an accelerator and you haven't seen it but as as far as much larger objects in the universe those are difficult to detect unless they're extremely large and having a big effect on the surrounding space time but but I think it would be difficult to see but again there's no indication that they exist because if there was negative energy particles we would see those in the inner laboratory in there and the accelerators every happens so no evidence whatsoever no unfortunately now back to the warp field if you were in a spacecraft sitting static within within the warp field and you were traveling across the universe at superluminal speeds what would that be like what what I mean would you experience radiation I mean what would being inside the work bubble be like yeah there's some people that have thought about that and they've even done there some simulations as to how the stars would look like if you're sitting inside a warp bubble so and essentially if you're going very fast even faster than the speed of light the first thing you would notice that the stars in front of you first you would see them are very small cone in front of you so you he stars only in a very small circular region directly in front of you everything outside that small cone you wouldn't see because the light wouldn't be able to reach you because you're going faster than the light so you wouldn't be able to see anything behind you because nothing would be able to catch up with you not even light so behind you it would be totally black but also in front of you in an archery generally you would see only a small circle of stars but again if you're going faster than light then any light that hits you from bit from in front it's going to be blue-shifted so it's gonna it's gonna increase in energy we call that a blue shift it's similar to what happens with with an ambulance when it's coming towards you you hear where high pitch and then it's moving away from you you hear in a very low pitch so it's the same thing like Doppler 4 it's Doppler effect so you would see the light coming towards you blue shifted so again it would be far more dangerous because something that normally just ordinary light would probably be hitting you like gamma rays and those are very dangerous and so you would receive a lot of radiation from the front of the ship and also anything else that is in your path if there's a rock in your path or something like that you would heat it at a huge speed and it would probably be deadly even a small grain of sand so yeah it would be extremely dangerous unless you had a very high efficiency shield to shield you from the radiation coming from in front and also from any small speck of dust that could hit you and destroy the ship so and if everything that hits you comes with a higher energy because it's shifted right so yeah that's that's interviewed see so whatever light comes in front of you would be shifted even probably towards gamma rays depending how fast you're moving it would be deadly and you will need a big shield but I mean would see also this this deformation only a small region in front of you would be able to reach you everything else want be able to catch you and I said I haven't done these calculations myself what people have done them and they're done simulations over the years about how it would look like from inside the work bubble and this is sort of the things you find so if you were traveling through space at well you know at faster than light speeds we're not even talking about relativistic speeds were we're faster than that and you you caught up material in front of your ship if you came out of warp in front of a planet you could do some serious damage to the planet by that material right that's a very good observation and so so something people have actually done calculations on everything is anything else in your path and doesn't directly hit you if it was moving forward say but not as fast as you you would it would catch it but then it would be sort of stuck in the front of the bubble it wouldn't come inside the bubble because it was moving towards forward so you it wouldn't actually hit you but it would be stuck in the front of the bubble so the front of the wall forms like a barrier that is sweeping particles and an energy in front of you and and you would be accumulating a lot of energy so any light for example that you catch because you're moving faster than light so if you catch light that was moving forward but not as fast as you because they're moving faster than light it would get stuck in the front of the bubble and then you you would catch a lot of light in that way and when you stop all that lie did it caught which suddenly just go forward to whatever it's in front of you so yes it would be extremely dangerous when anyone in front of you want you well it would be streaming in Jersey but you will stop it because nobody would hit them right but but even if you stop then all the radiation would be released and it would burn anything in front of you so yeah it's it's dangerous so and that comes the question of how do you slow down once you accelerate and we'll get to that in a minute we have to go to break but never point your work drive directly towards your planet destination exactly we'll be back in a moment with dr. el kebir the following program contains imagery from mark radar maker designer of futuristic hardware and founder of Holland space yards yes John I'm doing it now thanks mark thanks Tom thanks and we are back with dr. Miguel Alcubierre now doctor it's a big problem with traveling at these speeds is that you can also bring in time as a problem because such whenever you go faster than light you always have to ask the question what does time travel have to do with this tell us about that what what effect here do we have on time yeah well that there's separate issues here so one thing that people might might have heard is about the time dilation when you're travelling very fast but still lower than light but close to the speed of light then time moves forward very slowly for you as compared to things that are not moving right so if you go far away from the earth very close to the speed of light and then come back stay to a distant star a few years away and then come back then you might find that for you it was only a few years and maybe on earth it was a hundred or a thousand years or even more depends how fast you were going and how far you were going this is time dilation and it happens also if you travel slower than life now in the model I did for the warp drive I own purpose put out this effect so the the warp bubble that I designed doesn't have any time dilation but that's by construction and and since the construction is a little bit just like I wanted to make it and I did it simple it doesn't mean that if you could do it in real life it would be like that but in the model I have there's no time dilation so you wouldn't have this effect but the other fact that you also haven't when when you travel faster the life is worse you can show and this is something that Einstein showed very early from his special theory of relativity that if you can travel faster than light in principle you can build a time machine because if you travel faster than light then from the point of view of some of servers you're actually traveling back in time so if you do it there and backwards you could end up coming back before you actually left it's not easy it's a special construction but you can do it in principle so and disapprove general proof that any method you come up with that can allows you to travel faster than light can in principle be turned into a time machine that's true of the warp drive I didn't prove it myself but I hinted at it in my paper and somebody proved it a few about a year later somebody actually proved in detail so you could use a warp drive to build a time machine but you can do the same with wormholes so people talk about wormholes to travel fast and like if you can build a wormhole and in principle you can also turn it into a time machine so in a way you could step into the wormhole today and come out of the wormhole yesterday which again is weird but it's true as far as we understand any any way you come up with the travel faster than light allows you to in principle build a time machine now physicist is myself we don't like time machines because time machines mean you cannot predict the future because anything you were going to predict can be destroyed by somebody coming from the future I'm changing it try so so in principle it means that physics would not be predictable we wouldn't be able to predict what happens in the future if time travel is loud and it brings with it a lot of a host of paradoxes like the famous Brown grandfather paradox and all those crazy logical paradoxes so we don't like it we don't like time travel to the past and so Stephen Hawking in the in the early 90s and late late 80s I think he came up with an idea that he calls in very technical terms the chronology protection conjecture but in layman's terms it actually means that the no time travel by the air you want so he argued that the laws of physics do not allow time travel to the past and if you would were able to try to produce a time machine something would happen that would prevent him from doing it maybe the time machine would blow up in your face or maybe a black hole would form and and we came up with this idea it's not just a general argument in words he actually came up with some mathematical calculations based on quantum theory and he showed essentially that if you were able to produce a time machine travel to the past and a feedback a feedback loop would occur it's similar to what happens when you have a microphone and a speaker close by right so you hear the feedback because sound is going around and round and it's getting stronger and stronger because of the amplifier and everybody has heard that when you when you're talking in micro horn you get too close to the speaker so it's is the same idea but Hawking argues that it would happen in a time in a in a time machine and as you would be trapped in a look in time and going round and round Ronna would be amplified it would be focused and amplified with each loop and eventually this would create such a huge concentration of energy that either the machine would blow up or a black hole would be produced and that would happen essentially instantaneously because it's a time machine so from your point of view will be instantaneous it would switch on the time machine and it would blow up or produce a black hole and you would not be able to use it so that's essentially Hopkins argument and it's been around for 25 years it's still just a conjecture because there's no formal proof that this happens it's just an idea but it's a good idea based on very solid mathematical foundations but it's not a formal proof so that that for me is good right because it that means that it doesn't mean that you cannot travel fast and light it means that if you want to train you to faster than light spaceship into a time machine machine you wouldn't be able to do so and I think that's good that means you would principle might still be able to produce a warp drive and still don't have a time machine and at the moment you would try to use it to build a time machine you would die in an explosion or something so for physicists I think it's a good idea and and even for the warp drive is probably good news it means that that one of the arguments against it that is that is you could turn it into a time machine wouldn't be true that you wouldn't be able to turn it into a time so that's that's essentially the situation there in short it would be isolated and that since you've isolated a piece of space-time and you're not moving within it then you are not actually manipulating time well yeah exactly and you look if you just gonna walk one way true then that's true the thing cut comes around me if you try to do a return trip I mean you do it at a very special wave in print way in principle you should be able to do at a machine but this honking zarg youment tells you that you wouldn't be able to so the laws of physics protect us from Tumkur DOCSIS in this case that's essentially Hawking's conjecture the laws of physics protects us from from john travel Sontarans of the past time travel to the future is always possible sure just come back we're always we're always constantly traveling into the future we just can't go to the past exactly now how does this relate to I'm Stein and things like closed timelike curves because some people say that maybe backwards time travel might be possible through that mechanism what it's exactly that it's exactly that that's that's so when physicists talk about time travel we always mean in technical temps closed timelike curves so time travel from the point of view of physics is the fact that you have a trajectory that you can follow that brings you back around in a circle and and a trajector that you can follow is always a time like tragic turi because you can follow it in your own time so it's a territory that a particle but like ours can follow it's called a time like trajectory and if you can bend on itself and turn around back then it's called a closed timelike trajectory so anytime any type of time-travel in physics today it's always understood as a closed timelike loop and what Hawking is telling you that closed timelike loops cannot exist in nature because some something catastrophic as a structure would happen as soon as you can't want to produce one but every every sort of idea for Tantra will even gather who had an idea of a strange universe in which time travel could exist is called ghettoes universe and it's from the 20s of the 20th century that also has closed timelike loops so in principle you construct the geometries you can construct geometries with these loops that allow time travel and you can construct them easily math matter is not that difficult to come up with examples but what Hawking's tells us is that in practice you wouldn't be able to do this because this sort of space stance would be unstable against quantum perturbations that's that's essentially talking to argument if you forget about quantum mechanics and you just do a purely classical general relativity calculation in principle you can always make them it's not even difficult to come up with little models but in practice is if you try quantum mechanics would intervene and it would be unstable which is a big problem with everything you know when you start talking about stuff like if this is instability like a wormhole would you know yes there may be there's a wormhole at the singularity the black hole but it's going to open close rapidly and you're not be able to traverse it so and this and this is where the negative mass matter comes into play because you would need that in order to stabilize the whole thing oh yeah a wormhole on its own it's unstable and that's that even has nothing to do with quantum mechanics that's just pure relativity and pure relativity a wormhole in empty in empty space or with positive mass it's unstable if you want to stabilize that you need negative energy because the wormhole wants to close the question tells you that if whenever you open a wormhole it wants to close very quickly and you want to keep it open you need that repulsion a repulsive field and that's negative energy that keeps it open so that's the reason why you need negative energy in wormholes but it turns out and it's anytime you want to do something crazy with Einstein equations of relativity give you anytime you want to produce some crazy geometry like wormhole or a warp drive or something like that apparently always you need negative energy it sort of comes out always right anytime you want to circumvent the laws of the universe it says you're gonna need something special and back to the warp drive if you were able just to speculate to create the work field and travel at many times the speed you know relativistic speeds is there a speed limit could is there some barrier that says you can't go faster than this with the warp field there's no there's no speed limit in principle is just to go faster you would need more and more negative energy and the more negative renders you have the faster you in principle could go you could also use a warp drive to move slower than light it would be a very inefficient way to do it but you could use the work tractor moves more slower in life but and faster than life is as far as you as fast as you want to go depending on how much and negative energy you have available so there's no limit but there is a problem that I haven't actually mentioned yet this is the second problem with the warp drive we call it The Horizon problem and has to do with when you want to use the warp drive to move faster than light then in front of the bodies this bubble of the form space at the at the front region there's a limit further to which you cannot you cannot actually access anything in front of that directly from from inside the bubble you're inside the bubble you can only reach so far in front of the bubble but not all the way in front of the bubble so there's a horizon that forms there so this is a region you cannot reach and this is a problem because if you're supposed to be putting the negative energy in place from inside the bubble say you're in a spaceship and you have some sort of energy field generator or something like Star Trek and you use this generator to put negative energy at the front of the bubble to be able to move then there's a region you can't reach and that means you cannot put enough negative energy there and you wouldn't be able to produce the bubble in the first place so this is the horizon problem it doesn't if you want to use the warp bubble to travel slower than light and that's no problem but if you want to travel faster than light then it's a big problem and that means that the spaceship itself would not be able to produce the required field it would have to be produced from the outside and that again it's it's a big problem right because somebody would have to be bare producing the negative energy as you as you go along as you pass it you could imagine maybe a sort of big cube like like a like a subway to you right a big tube through space with field generators are switching on in time as the spaceship is going up but that's that seems like completely crazy right - bill it's you from here - Alpha Centauri so essentially you need to build a highway before you could use the drive so you would have to have a way before you send anything through it yeah so how would you do that if you you would have to do it at sublight speeds you'd have to have a spacecraft you know and you would have to leave some sort of negative mass generators of some sort in front so to build a highway to it to have it it's sort of like gas stations actually where to send the spaceship before slower than light that would be living behind it negative energy generators along the way and they would this would give you the sort of highway and once it's built something can go through it faster than life but it would have to be built before and they would have that would have to be done slower than life yeah now once you had this highway built and you could traverse while its sublight speeds obviously it's very difficult to traverse the universe but the galaxy say you were able to build a highway over millions of years and create this this sort of transit system what Oh what's the warp bubble could you detect that if say say an alien civilization millions of years ago created such a thing and you were looking for alien tech no signatures what what would that look like this Alcubierre warp drive highway system I mean could you detect it or would it just be not visible I think it would I've never thought about this in detail but I think if it was moving directly towards you you should be able to see a burst of radiation when they're using it but if it's not moving directly towards you then I don't think it would be detectable I don't think they would be able to see anything but if it's if it's pointing directly at you then yes you would see a burst of radiation especially when they slow down as you mentioned but yeah that's you should see but but I think it would be difficult because something very localized and it's not really pointing at you then I don't see I don't see what you would see undetectable you mentioned slowing down once you get going how do you slow back down Wisconsin that's exactly what I was saying is this is the same problem with the horizon so you wouldn't be able to slow down on your own somebody would have to do it from the outside so somebody would have to switch off the highway as you arrive at your destination you shouldn't you wouldn't be able to switch it off from inside it's the same is for the same reason because you cannot reach the front of the bubble so you cannot tell it to switch off at the front at least and and it's exactly the same problem so initially when I went when I did this paper I mentioned this also in passing I mentioned that you shouldn't be able to wouldn't be able to slow down wants to turn it on but then I realized the problem was actually much worse you wouldn't be able to turn it on in the first place right so that's because of this horizon problem but is it basically the same problem if you're traveling faster than light you cannot reach the front of the bubble which means you can't manipulate it and you can I'd you cannot turn it on you cannot turn it off you can't manipulate it at all somebody has to do it from the outside that was already there waiting right so essentially you cannot ever reach the brake pedal it basically yes is a brake pedal was so far away you wouldn't be able to reach it yet yes you can't ever reach it physically now inside the warp bubble you would also probably have problems people have said that you would you would be cooked by radiation can you can you get into that yeah well that's what I wanted mentioning anything coming towards you from the front as you reach it with a warp travel any radiation that was pointing towards you would actually be blue-shifted there any of you moving much faster than light and light it would be shifted a lot so even something that was ordinary radio waves that was completely harmless if you're travelling sufficiently fast faster than light with the bar power it could be blue shifted towards gamma rays that can kill your friend because the radiation would be so intense so you would need a very good shield if you planning to use this with traveling fast a lot but this is a problem if you move slower than light if you build a spaceship that could go say 99% of the speed of light then again that's a danger this is radiation that's coming towards you ordinary light is blue-shifted and it's this blue shifted towards gamma rays it would be deadly and and if you find a small rock and it's hitting you in 99% the speed of life then it could destroy the ship so this is a problem even at slower than light speeds if they're sufficiently high right if and 99% the speed of light is already a big problem so it's not a problem that's just related to the warp drive is the problem of moving at very high speeds on a scale of 1 to 10 with 10 being the most unlikely where would you rate the possibility of the warp bubble that we could actually at some point in the far future create this how likely is it oh yeah so 10 is the most unlikely yes so I would probably putting it to 9 yeah I think it's very unlikely if you ask me even though it's my own idea and I like it for personal reasons I think at this moment it might seem even more likely to have wormholes and those would have fear problems still wormholes are not likely at all because we have no idea how to build but but they have they have for your problems if you could build a wormhole then you wouldn't have this horizon problem you wouldn't have this radiation problem a lot of the problems with the warp drive are simply not there in the case of wormhole but again nobody knows how to make a hole in space so we have no idea at all how to create a wormhole but it seems less problematic if you could actually have one so yeah I think it's unfortunately for myself because it's my own idea but I think it's highly unlikely at this point still an interesting idea and it's always fruitful to entertain useful ideas because that's where maybe other useful ideas come and on that we are out of time dr. Alcubierre thank you for joining us thank you thinking about far future technologies is a very uncertain thing the vexing at times given what I do imagining something is one thing and actually engineering it and building it is entirely another but imagination is important that's what starts the ball rolling and gets people thinking about the nuts and bolts of an idea and while the materials and technology needed to create an al Kabeer warp field why in the future perhaps even the distant future for all we know it is at least a seat for thought on the subject right now that's important and who knows there may be other ways to defeat the speed of light there are always the possibilities of wormholes or even ways we may not have thought of yet we do not yet have a complete understanding of our universe only a partial one so the concepts that spawn out of science and sci-fi in the coming years centuries or millennia may serve as seeds to push us further who knows where we might end up John yes I think it's time to talk about getting rid of the car but wait well I have an idea oh this isn't a good sign if and I stress if if we can get al Kabeer to drive the LeBaron we can increase its value tenfold I can see where this is going wait stop where did you how did you how did you even use a spray bottle we'll figure that out later and joining me next week will be dr. Duncan Forgan for a discussion of the Fermi paradox and the solutions to it [Music] [Music]

Channel: Event Horizon

Views: 1,198,460

Rating: 4.7676444 out of 5

Keywords: event horizon john michael godier, alcubierre, alcubierre warp drive, can we travel faster than light?, dark matter, dark energy, alcubierre drive, warp drive, nasa, physics, space, einstein general relativity, hyper fast travel, the alcubierre warp drive, can we go faster than light?, hyper fast space travel, nasa eagle works warp drive, faster than light, event horizon, can we go faster than light, isaac arthur, alien

Id: JafY92PhgKU

Length: 64min 2sec (3842 seconds)

Published: Thu Jun 06 2019

Reddit Comments

[u/elkridgeterp]

First, I apologize as I am not a scientist, physicist or someone who can speak to these topics with any authority. I think I followed the video and understand the concept where they deform space-time so that you can traverse great distances that would conventionally take light years.

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Here is my question. I've heard where it's not just light that travels at C in a vacuum, but anything massless. Gravity. Electromagnetism. So if it would take extreme mass (or extreme energy) to deform space-time to the scale needed for interstellar travel, wouldn't the process of deforming space-time be limited to C? The piece of space-time that is 10 light years away would not notice the effect of the mass/energy deforming space-time for 10 years? So you can bring that point closer to you at the speed of C, but not faster than the speed of C? Now being able to get somewhere 10 light years away in 10 years is fantastic, but I don't see how you could get there any faster than 10 years.

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Am I missing something obvious (or not obvious)?

[u/SLSbigbastard]

You can get to a place quicker than light could, you just wouldn’t be traveling faster than it