It's impossible for any type of material having a significant amount of weight to it to make the long journeys to other worlds in a time frame that would be convenient. One who have to become converted to light to bridge the distance. Or one who have to travel astrally. There is no metal or ship that could survive the rigors of faster than light travel. We'd have to become light to traverse to other galaxies.
@knossis1 You're neglecting relativity. For the people on board, the journey could actually be quite short depending on how close you approach the speed of light. And it's not impossible at all assuming you can find a suitable way to accelerate..
@Prospekt0r I get your point, but barring science fiction and dilithium crystals,(dilithium is also the scientific name for a molecule composed of two lithium atoms) we have yet to find a suitable way to get anywhere close to the speed of light. My research has led me to belive the ancients traveled astrally, which would be a lot more effecient & practical. But I like u believe anything is possible given time. So who knows, in the future we may have warp engines and what not.
@knossis1 If you're looking to get to alpha Centuri, you don't even need to get close to the speed of light. 10% is sufficient and the journey would only take around 40 years. Achieving such speed is possible with current technologies (no anti-matter needed). If we want to go further we just have to find a way of mass producing anti-matter. Worm holes and warp speeds are theoretically according to general relativity as long as we have a negative mass (as of yet no such thing has been found).
Yeah, the Venture Star runs a completely ridicuolous accelleration. But IIRC if the acc is cut to 1/100th (travel time ~60 years) it's a lot less farfetched.
When I did the math for a antimatter RAIR/Ramscope I was planning to use for a novel I got to Alpha Centauri in about 80 years with only ~15% of the ship's mass being AM fuel and only ~20 square miles of radiators for the 100,000 ton craft.
Perhaps the ship manipulated the space-time continuüm by pushing away baryons or perhaps the ship concentrated the amount of dark energy around itself. It's a movie, everything is possible.
How do you know it is 100000 metric tonnes? The craft looks much lighter, like around 10000 metric tonnes? And keep in mind that the craft does have a solar sail as well.
Actually the mass doesn't matter ... to get to .7c requires a proportional amount of antimatter.
I just saw Cameron's little book about Avatar in Walmart. I checked to see if he gave a mass for the Venture ISV ... still ... no mass. The absence of a stated mass is like selling off all the steel from the World Trade Center ... they're hiding something ;o)
@Bantokfomoki I agree that a six year trip time with an antimatter rocket is impossible, but trip times less than a human life time would definitely be feasible. A 40-50 year transit time would only require a velocity of about 10% of c.
@SkrillToss I don't think that the trip is feasible in less than 1000 years with a huge flotilla. I have zero confidence in any kind of short trip at all. If you thoroughly examine the subject, you will just get more and more pessimistic.
@Bantokfomoki I seriously can't believe this. You have repeated time and time again that this design was impossible because of the virtual impossibility to reflect or at least redirect the gamma rays produced by the engine... And NOT ONE person picked out that they don't need to be. You're right, an antimatter engine isn't 99.9% efficient, 44% of the reactants' mass energy ends up as gamma rays. Where you're wrong is that you assume that these gamma rays interact with matter in the same way...
@OldDirtyRatbastard Gamma rays must be produced in pairs (linear momentum conservation). One goes out the ass end (the propellant) and the other one MUST be absorbed by the front of the engine nacelle ... or ... the reaction produces no thrust. Get it? The gamma ray can't push the ship if it doesn't hit it (action-reaction). If a large proportion of the gamma rays hit the body of the ship ... you're toast.
This ship [as designed] would last less than 1 second if you started the engine.
@Bantokfomoki than lower energy photons. Well, they don't. Light at these high energies has an attenuation coefficient for materials normally opaque to it, and that coefficient goes down as the photons' energy increases. The rays released by proton-antiproton annihilation happen to be the most energetic there are outside of galactic nucleus events, meaning that nearly every material is transparent to them : they don't induce heat and don't destroy atoms, they just zap through into space.
@Bantokfomoki Now, let me say that i abhor the movie, but that spaceship is everything but silly. It was studied in depth as a concept, way before the movie's idea even existed, by Stanford university professors who found that the only impossibility preventing it from reaching over 60% c in a few years of acceleration was the antimatter requirements in the thousands of tons. The study found out that the radiators have no heat to dissipate from the engine, they actually only serve to...
@OldDirtyRatbastard Where do you get the energy to refrigerate the tungsten? The refrigeration would be a function of the fuel use ... so ... you'd need lots of refrigeration. (And by "lots" I mean we don't have a word in the English language to express such a large amount ;o)
@Bantokfomoki refrigerate a tungsten shield which is purposely placed in the exhaust to cast a "shadow" within the gamma rays, protecting the crew compartment as well as some EM perturbation-sensitive electromagnets. You can be sure that these people did more calculations about the feasibility of this ship than we probably ever will, i can send you a link to the full university paper if you want. Intersestingly, the shield would get so hot that the light it would radiate would produce thrust...
@OldDirtyRatbastard I thought you said gamma rays just zip through everything harmlessly ... so ... why does the crew need to be protected? ;o)
I agree that the people who did the calculations did more than me. They too found the scheme unworkable ... therefore ... they neglected to mention the mass of the ship ;o)
I call this what it is ... scientific fraud. But it's a harmless fraud. So, I don't really care. I liked the movie very much.
@OldDirtyRatbastard No, it wouldn't generate thrust. The heat given off as photons would go in every direction and produce no thrust at all.
Lastly, if a gamma ray hits something ... it destroys it. If it doesn't hit something, it's useless as a propellant. If enough gamma rays hit anything at all ... it disintegrates.
@Bantokfomoki The visible photons can be collimated by ordinary mirrors, producing some thrust.
Indeed, it destroys, IF it hits. And a gamma ray with enough energy has too small of an amplitude to hit anything less dense than tungsten. The Stanford spaceship had a reaction chamber built of beryllium, and their calculations proved that it would whitstand several grams of matter/antimatter annihilating per second thanks to transparency.
Now, it seems that we've had a misunderstanding. I've never
@Bantokfomoki said that the gamma rays could be used as an useful propulsion system, i gave the 56% efficiency because these 44% of gamma rays are, for all intents and purposes, useless. But proton-antiproton annihilation produces charged and massive pions in addition to gamma rays. That's what used as propellent.
The crew needs to be protected because humans are not made of bulk material. Even a single atom knocked out by a single gamma photon in any of one's cells can end up as cancer.
@OldDirtyRatbastard Using pions as propellant significantly reduces the efficiency of the engine. You're gonna' need a lot more antimatter. Ramp up that fuel ratio.
@Bantokfomoki Oh, you are right about that. The film version is a perversion of the original which is like a space rat-rod : bare bones. The engine is a single toroidal coil, the shields are not the stylised fins of the movie but a small tungsten plug on the poymer thether, the crew compartments are disproportionately small, the radiator is an invisible cloud of magnetic fluid droplets doubling as a dust shield, and the power systems are hidden around the cylindrical fuel tanks.
@OldDirtyRatbastard If you throw out one pion ... another one has to hit the front of the engine nacelle to produce thrust. This produces damage, heat, annihilation. You can't control the entire solar output to the earth within the Venture's engines. It's so ludicrously impossible. A Tsar Bomba every second for millions of seconds?!
Just because a man is a scientist does not mean he's an honest man. The thing is a "paid for" fraud. And, as I said, I don't care ... the movie was just swell ;o)
@Bantokfomoki material annihilated to get their lousy 1.5G acceleration.
I actually read that paper, and the guy's conclusions are mathematically correct and pretty much indisputable. There's something called "peer review", you can't pay scientists from universities all over the world to agree with a "fraud", unless it's a matter of interpretation. And this really, really isn't.
The bad efficiency is also accounted for in the general effective exhaust velocity for the rocket, they found 0.58c...
@Bantokfomoki so even though the gamma rays would pass through harmlessly, there's still a chance they's give someone a tumor during the 6+ years of acceleration.
They did not ignore the mass of the ship, they calculated a fuel to mass ratio of 22 to 1. The payload was set at 400 tons, requiring 8800 tons of antimatter. The ship is only very long because the crew quarters are dragged at the end of a 10km thether. This distance from the engince minimises the amount of gamma rays reaching the...
@OldDirtyRatbastard Look at the ship in the movie. Do you really think that weighs in at ONLY 400 tons?! My conservative estimate was 100,000 tons. I later revised my "mistake" to 900,000 metric tons. Hmmmm .... did they use a shrink ray, ya think?
@Bantokfomoki Now that actually looks like it weighs 400 tons empty, but it was too ugly for the director's needs.
Nope about the pions, you are forgetting that the enormous amounts of energy imparted to them goes to their speed, but their rest mass remains small (if i remember right, around 100 MeV*c^2). This means that they have little momentum and can be redirected into a working exhaust by a simple magnetic nozzle. On the other hand, the thrust is crappy, which is why they need a lot of...
@Bantokfomoki shields, diminishing the need for refrigeration.
You could imagine many things a generator for the heat pumps... Solar panels, a magnetic "turbine" in the charged particle exhaust, an array of fuel cells... Anything that doesn't produce too much heat.
The Venture Star uses magnetically confined antimatter/matter annihilation. The "unobtainium" is supposedly a room temperature superconductor, making the required magnetic field much easier and cheaper to make. Once the engine is fired at about 1 g, it accelerates for about 3 years, then fires breaking engines. I hate it when people who aren't from scientific backgrounds try to lecture on science and engineering. Not only is this possible, it's probable in the next 300 years.
@golthimere There is no known way of containing an antimatter annihilation. The product of such an annihilation is primarily gamma rays. They cannot be redirected by a magnetic field or mirror. Whatever they hit ... they destroy. By conservation of linear momentum at least two gamma rays MUST be produced going in opposite directions. One of them must therefore hit and ionize an engine atom. Goodbye engine (in the first nanosecond).
@Bantokfomoki Actually, if we ever figure out how to produce or capture monopoles we would probably be able to produce all sorts of exotic materials. These might include mirrors capable of reflecting gamma rays, hyper dense matter and virtually indestructible materials. This is obviously speculative, but within the context of the of the film it's not that much of a stretch if you replace "unobtanium" with "monopolium". It's certainly less far fetched that reactionless propulsion..
Oh and by the way, I'm not dissing on you man. Your video brings fourth pretty good information. Antimatter engines may not be impossible though, but pretty impractical for a lot of other reasons than what you stated I admit.
@yemo34 the worst part about antimatter is ... we don't have any. And ... to make some would require more than the amount of energy we'd get out of it (2nd law of thermodynamics) ... even if we could make it
Antimatter rockets would probably only be practical in hybrid systems that use it only to "catalyze" fusion reactions. They might become feasible for a civilization that can harvest the solar out put of several stars, but they would probably need some kind of FTL transit system like traversable wormholes which are even more unlikely/speculative. And if monopoles actually exist, and can be created, antimatter rockets would become obsolete anyway.
Another possible application would be a Bussard ramjet that uses antimatter as fuel and interstellar hydrogen as the reaction mass. But, then you still have the problem of boosting the ramjet up to about 1% to 6% c. before the ramjet would actually work. This might be possible with a large enough laser sail.
@Bantokfomoki There are modification of the concept such as the RAIR, as well as a few others. They usually involve reducing the "drag" by not slowing down the hydrogen atoms for fusion, and instead use antimatter to annihilate the hydrogen as it passes through the rocket. So, it's not completely dead. Also, some of the criticisms of the concept depend on some assumptions. We are obviously hundreds of years away from testing these various concepts.
There are some GUTs that involve exotic forms of matter and proton decay that might make relativistic rockets, unimaginably strong/reflective materials and even non conservation violating reactionless drives possible. I wish Avatar was set much further in the future, and I wish he had come up with a more plausible form of exotic matter other than "unobtanium". Based on the teaser, It looks like Niel Blomkamp's next movie Elysium will be a more realistic take on interstellar travel.
@LouistheHedgehog It doesn't matter if it's a hybrid ... it still won't go to Alpha Centauri in less than an human lifespan. That's my whole point here. You can go there ... provided you are willing to spend a few thousand years in transit. Any mechanism conceivable can't get there quickly if the laws are physics are valid. It's technologically impossible. I've done the math and it's not even close to possible.
I doubt it is impossible for space travel to exceed our modern parameters. Avatar takes place in the future, and not the near future either. And how can we even say that are laws of physics wont be drastically altered by that time. Science had many paradigm shifts, extreme ones. Like how relativity brought Ideas such as time dilation into play. In essence this IS time travel. An Idea someone like Newton would laugh at. Uttering the word impossible measures a degree of cultural arrogance.
@yemo34 You should also keep in mind that Newton's laws are still valid to day within a certain scale range, it's only when you get to the macrocosmic and microcosmic that they need to be expanded upon.
@SimKoning As you can see in the above video, I agree. I used them to calculate that interstellar travel using a reaction engine ... of any kind ... will never get us to our nearest neighbors in less than a few thousand years.
@yemo34 Science has paradigm shifts ... nature doesn't. It's just there. The laws of physics are the same in the Avatar scenario as they are now ... hence, the ship is impossible.
Science is the process by which we understand nature. There are no written down rules that say how nature works, anywhere. Scientists take evidence, and formulate theory's on how it "might" work. We are limited by our tools and senses. Supersonic flight, nuclear weapons, and computers were not possible 150 years ago because of those reasons. For all we know the ship could have force fields on it's engines.Sounds like fantasy now, but at one point so was a moon landing. It's not impossible.
@yemo34 What we are limited to is ... 1) movement toward or away 2) movement round in circles 3) expand or contract (like a balloon) 4) rotate on axis 5) hot & cold 6) electromagnetic effects 7) resonance effects Whatever we can get out of these is all we will ever get ... forever ;o) [and most of these are made from the first four]
@yemo34 He's wrong and he knows it. What he does is refuse to listen to those who have proven him wrong. It's sad really. He will continue to run his pathetic little site for the rest of his life. Let him have it.
The ship in Avatar is the most realistic starship ever put on the big screen: it's based on Dr. Charles Pellegrino's and Jim Powell's Valkyrie concept, which if feasible, would reach a maximum velocity of 92% c. There is also a version with a mass ratio of 1.5 that would reach 10% c. Cameron's version is actually a light sail/fusion/antimatter combination. the primary flaw is not so much the antimatter rocket, but the massive laser battery that would be needed to propel it up to 70% c,
I'm a little skeptical about you mass estimate. You are comparing a machine that would be made mostly of ceramics and extremely light, stronger-than-steel materials such as carbon nanotubes with an armored aircraft carrier. The Valkyrie concept is one of the lowest mass starship designs out there because the rockets are placed in front of the crew module. There are several other plausible rocket designs out there that would reach a significant percentage of c.
If I'm not mistaken, your skepticism in regards to "the standard model" seems to be rooted in the fact that you think UFO flying saucers are real. I'm a little stumped as to why you are skeptical of heavily tested hard science, yet you have concluded (based on anecdotes and blurry photos) that flying saucers powered by reactionless drives are real. It's like believing in fire breathing dragons before concluding that biologists "got it wrong" to make room for your presupposition.
@SimKoning The evidence for the reality of UFOs is ... to put it mildly ... overwhelming. Because they arrived here from there ... and behave so cavalierly ... I must assume that it's relatively easy for them to get here. Ergo ... the supposition that the conservation laws can be overcome.
@Bantokfomoki I think you are begging the question: the evidence that the laws of thermodynamics and other branches of physics are correct is *far* stronger than the evidence that UFOs are actually alien visitors. There is about as much evidence for saucers and Greys as there is for Bigfoot and ghosts; that is to say it is in the form of anecdotes and questionable photos/video.
However, I do find it hard to believe that aliens have not been here in the form of probes of some kind. The Fermi paradox combined with the age of the galaxy suggests to me that we have been visited a few times, but it could have been only few cases, by several different forms of life over millions, if not billions of years. After all, macroscopic complex life has only been around for about 600 millions years out of 4.6 billion year lifespan of this planet.
Then when you also consider that our species may not be all that interesting to an intelligence that may have been evolving for a billion plus years, combined with the fact that we have only been around as a species for a little over 100,000 years, I can't help but suspect that we are little more than ants on the side of the road.
@SimKoning No... we are special. They've been waiting for us. Thinking beings are all there is to wait for. I suspect that they have had cities on the earth in times past and have moved off-planet to let us evolve.
@Bantokfomoki Interesting speculation, but I'll be the first to admit that that's all it is. Asserting that aliens think we are special is question begging, because you have yet to demonstrate that aliens even exist in the first place. I reject the notion that UFOs are proven to be alien, because I've looked at the evidence, and I find it no more compelling than ghost sitings. So, ultimately, we are left speculating about the Fermi paradox.
@SimKoning I completely agree that the evidence for the conservation laws is much greater. Up until a decade ago I would have bet my life on them.
The evidence for UFOs is about 1000 times greater than for Bigfoot however. Given that "they" are here ... I have to postulate some way to get round the conservation laws. So ... I did.
It cost me exactly nothing to look into and think about the subject ... just my time.
@Bantokfomoki You say it's a thousand times greater, yet I see nothing other than anecdotes and blurry photos/videos. There may be *more* people claiming to have seen UFOs than Bigfoots, but using that as an argument is little more than making an appeal to popularity. The quality of evidence must be considered. Also, there are reactionless drive solutions that do not involve violating any of the conservation laws, such as various warp metrics.
@SimKoning The mass is irrelevant. To get to .7c you need about twice that mass in antimatter to get to the designated speed. This is NOT EVEN CLOSE to possible. It's orders of magnitude off.
Antimatter aside, we should not rule out breakthroughs in technology that we can barely even imagine; we are talking about hundreds, if not thousands of years in the future here. For all we know, an advanced civilization may develop exotic forms of matter and energy such as monopoles and/or negative energy, which in turn could lead to rockets capable of high relativistic speeds, and in the case of negative energy, some form of reactionless propulsion.
Then there is the fact that human lifespans will probably be measured in centuries by that point, and, for all we know, our descendents may evolve to be partly or entirely mechanical.
@SimKoning While the rocket in the movie has serious problems, an antimatter rocket is not an impossible thing. The more realistic concepts involve ships that are essentially a big rocket (and little else) pulling a crew module on a several mile long "string". The real problem with the one in the movie is that the radiation would have killed the crew, primarily due to the fact that the "string" pulling the crew is way too short.
@Bantokfomoki Since I'm not a physicist, I'm forced to side with experts in the field (NASA researchers for example), which seem to think that advances in technology such as the VASIMR plasma rocket may lead to rocket systems that you believe to be impossible. The Atomic Rockets page has a rather long list of plausible rocket concepts ranging from antimatter, fusion, antimatter catalyzed fusion, antimatter nuclear pulse, laser sails, etc.
@SimKoning You're right. The guy's error is pointing to the way too small engine in the movie & pointing out it can't contain the tremendous heat generated. True; but we can make changes. We are trying to achieve a velocity of app. 1,000 times what we can achieve with our best NERVA thermal nuke engine. That is 7,000 miles per second. With 2 stages this is 14,000 miles/second. The heat energy we must handle will be 1,000^2 = 1,000,000 times the heat energy a NERVA engine would produce for the...
@SimKoning ..same thrust. Step 1: decrease thrust ratio of the engines. The NERVA, in larger sizes has a thrust/weight ratio of 50 to 1. We decrease that to 1 to 20. This gives us a thousand fold increase in our ability to handle heat. Not enough. Now we reduce overall thrust. For NERVA we aimed for 1.3 g's. Decrease that to .001 g's. we get a 1300 times reduction. Our total now is a 1.3 million increase in our ability to handle heat as compared to NERVA. We are there; the stars are ours.
@SimKoning I don't 'believe' that such rockets are impossible ... I KNOW that they are impossible ... by way of the conservation laws. The laws THEY are breaking with plasma rockets aren't the laws of physics. Rather, they are local, state and federal statutes concerning fraud ;o)
@Bantokfomoki I'm confused by what you mean by fraud: the VASIMR rocket actually exists and has been tested. The whole point is to develop a rocket that uses superheated plasma while avoiding that nasty problem of your rocket melting. Regarding the energy needed for the production of things like antimatter, that will depend on the amount of energy we are able to utilize in the future. We haven't even reached 1 on the Kardashev scale yet.
@SimKoning It's a fraud if they say it can be used for interstellar travel. If they want to use it withing this solar system ... go for it. There are lots of viable things to do in our immediate neighborhood.
@Bantokfomoki Actual rocket scientists seem to disagree with you. Charles Pellegrino, the scientist that actually designed that rocket for Cameron (they are friends I think) thinks a rocket capable of relativistic speeds (10% to 70% c) will be feasible provided the fuel can actually be manufactured, which of course is (to say the least) the real problem. The technologies that may lead to such a rocket are already in development-
Antimatter has been created contained in very small amounts, the Vasmir plasma rocket, which utilizes a magnetic bottle and "nozzle" to propel charged particles is already being developed by NASA, super light stronger than steel materials such as carbon nanotubes have already been invented. Assuming that this will not lead to much more advanced rocket systems may be as shortsighted as thinking that aircraft technology would have stopped evolving past WW1 fighter planes.
i understand the philosophy behind your thoughts but avatar is just a fiction how can someone waist time to be serious about a beautiful movie witch was made by human through vision (fantasy) by human. that can open doors to read about many subjects -space travel, physics,antimatter, infinite space,propulsion engines so on so forth,but this person have to get out from the dream world i think.
I'm pretty sure there are methods to get to Alpha Centauri within a human lifetime. Not possiblle until into the next century, but still plausible within our current understanding of physics. If you can average 0.1c, then we get there in 42 years. We could manage that with antimatter engines, or even antimatter catalysed fusion.
it's not just anti matter, the ship in avatar(which, by the way, is more accurate than most any other sci fi ship specifically star trek/star wars) used a photon sail and laser propulsion. im no good at science, but please take that into account.
@Bantokfomoki well, it is fictional story(and my favorite) and the ship had to work for the plot, so can you blame them? at least it more sense than most sci fi ships.
totally missed the point. a comet, LIKE THE EARTH, is simply ''falling'' in the gravity of the sun. its falling in an elliptical orbit, and just to be clear, there is energy involved. right now, gravity is applying energy to you and me and puling us down. i don't know how much, but a planet or comet orbiting a sun has a lot of energy.
Two things here. (1). the ship venturestar looks more like a 100 years travel design, so we should perpare for a 100 year round trip journey at a attainable speed. (2). I believe the distant caculated by scientist about light distance are inaccurate, ( WHY? ) we do not possess a device thank can measure over the great-great almost impossible distance. If we mis-calculate here, we will over-shoot our destination by ???? which = death!
@legendhunter47 The distances to the nearer stars are calculated with a great deal of accuracy. It's a trigonometric exercise where the distance from Earth to the sun forms one side of a VERY long triangle. By measuring the star's angle from the horizontal at a given time on one day, then measuring its angle 6 months later at the exact same time, the length of both the base and hypotenuse can be determined very accurately. They are planning a probe to multiply that baseline by a factor of 40.
WTH man? This was a stinking pile of directorial and scriptwriting masturbation. It systematicall abused us from start to finish, and as far as I am concerned is by far the worst movie ever made - even worse than "Hollywood Cowboy" and "Sasquatch".
I think both show promise. We need to learn a lot more about space-time in order to make them work, but I think that eventually we will develop a warp drive based on similar concepts. But unless a scientific miracle occurs soon, I doubt FTL will exist within this century. I think though, that antimatter is the best hope we have for the next century for large starships. But there are Von Neumann probes, they seem to be the most practical. Look them up, they are very exciting.
@sniperboi96 You don't have to worry about anti-matter drives in the next century ... you only have to worry about how to sharpen a good "digging stick" to get at roots to eat. You need to know how to "flake" rocks to make spear points ... stuff like that. Forget about interstellar space travel for at least another 2000 years. In the next 1-2 centuries more people will die on the earth than ever before or ever after ... regardless of what anyone thinks, does or says about "Avatar".
It is possible to go to Alpha Centauri in a human lifespan if we were able to go a mere 10% of the speed of light. That is possible with an anti-matter drive. I like people who say "it cannot be done" because it makes others who dream and truly innovate able to push forward and do it, much to the dismay of naysayers. Trans-atlantic cables carrying signals with our voice was once deemed impossible, as was supersonic speeds. Thank you, you've motivated my to prove you wrong.
@eskercurve Any examples you note about people overcoming the "naysayers" are about 3 orders of magnitude easier than interstellar space travel. You site a 1,4,3,6,2 magnitude problem while interstellar space travel is on the scale of 3000, 5000, 2000 etc. Dump a cold bucket of water over your head. You're going nowhere unless you go REAL slow ... or ... find an end round the conservation laws.
Ok now I know u definitely lied u arent a physicist u should talk to mechanical engineers like myself and physicist who are working on space propulsion right now. U do know what ur talking about but ur just not current.
u should always be careful saying impossible. because so call impossibilities have turned out to be possible and we dont have a complete knowledge of physic its best to say unlikely but we might be able
Thank you for the video, it was very informative and well thought out. You had some valid points. However, I do believe that antimatter is the key to interstellar travel. But I doubt that we will be able to get starships above .5c (besides electromagnetically accelerated nanoships). I have been trying to design an antimatter rocket, and I your points have made me rethink some aspects. Thank you.
let's ignore antimatter problem for a bit here. Say we use reaction engine. Is it possible to contain a massive explosion needed to propelled the ship to a necessary speed within our current technological capacity?
@lanunselat You mean an engine like a regular rocket? No. That can never propel a ship to significant fractions of light velocity because of Tsiolkovsky's rocket equation. The amount of fuel required is way, way, way beyond technological possibility.
Containing the explosion isn't the problem ... it's hauling the fuel needed to propel the fuel. That's what the rocket equation is about. It's simply the law of linear momentum conservation as applied to space travel.
2 things that prove your thery about never going some where far off in a human life span. Well before I say this one of these was not discovered untell 2011. CRYOGENICS! and that one new element german scientise found that can go faster than light and is carriable
also... your aircraft carrier to ship ratio is inaccurate.. as one of the shuttles on the avatar is actually in scale at least 1half times the the size of a 747 jet which would make the starship considerably bigger than a nimitz class carrier in scale
LMFAO.. not gonna lie when i first started watchin i thought here we go another idiot savant deconstructing a sci-fi movie for its inherent technical flaws... but after watchin i was pleasantly surprised &amused at both your seemingly accurate calculations &incredibly black (if unintentional) humour
however id like to ask why u didnt in your calcs include for time dilation (if it matters) &would also ask what difference ship mass would have if any in vacumless, frictionless space?
@theblaquebaastid At .7c and 6 years, time dilation isn't a significant quantity. You need to get over 90% to make a real difference. The mass of the ship won't make any real difference. Antimatter is too energetic a fuel to use for extremely high speed in short time periods (like 6 months).
Correct me if im wrong, If the power is correct, wouldnt that 10^17 watts be 10 kilograms of matter per second? And multipliying that by 15000000 seconds in 6 months that is 150000 tons of matter on board that will desapear(just for the acceleration) that is more that the total mass.
@TARATATANTATAN When I say "mass of the ship" I mean the hardware-payload part. Yes, the "gas" weighs more than the ship. For a ship attaining .7c via antimatter you need to about double the payload mass in fuel. (That's using Tsiolkovsky's rocket equation)
Because you are not considering that the antimatter is traveling at the same velocity of the spaceship and thus it needs less energy from that advantage point to continue accelerating the spaceship that what you see from the ground. You have to analise the problem from the spaceship frame reference if you want to see them as the propelant sees them. You will find that much less energy is requiered from the advantage piont of the propelant.
You are not taking into account that the propelant or antimatter or whatever is traveling WITH the spacehip. From your ground frame referece, E=1/2mv^2, and its derivative: E'=mva=F.v, if v=at, so the kinetic energy doesn't increase in a linear way, it depends on the velocity of the spaceship. ¿But how can that be if the force (F) of the engine is constant, and so the release of the antimatter energy?
you say its "physicaly imposible" to have an engine giving that rate of energy with out melting, a rate of 200000 or what ever saturn rockets, but, why is that imposible? you can in principle imagine 200000 saturn rockets on the bottom of a spaceship all running at the same time... nothing metls there... you are just involved in a falacy of considering the total amount of energy instead of the density of energy. Say its uneconomical, not physically impossible
@TARATATANTATAN It's not physically possible. In my little addendum to this video, I took another look at the energy requirements and found that I'd need much more ooommph. Like 14 Tsar Bombas per second instead of one or two. That's 7 Tsar Bombas in that confined engine per second in each engine. That's so far impossible it's laughable. Unbelievably laughable.
@TARATATANTATAN A Saturn rocket doesn't burn antimatter. There is not gamma ray problem. If you used 200,000 Saturn rockets ... the ship would work ... but only until you ran out of fuel and you'd be no where near even 1/100 c.
you are too generous with that film, what about the garden of eden gaia type nature in pandora instead of battle for survival of darwin, and the statistical improbabilities of finding a humanoide animal having evolved on another planet independently and coinciding with them in space and time
Regardless, I agree that this is a very silly ship and the whole premise of the film is quite absurd. Photon sails accelerating a piece of paper, yet alone a 5000 ton ship at 1.5g is just stupid, especially after you consider the divergence of the laser beam at such distances. Plus, manufacturing the tons of antimatter you'd need to power one of these ships would have a huge opportunity cost, and would more than negate the payback from the unobtanium. May as well synthesize it.
@SeersEnlightenment You're a bit off in the tonage. The ship actually would weigh in at about 900,000 metric tons. You're off by a factor of 180 ;o)
But, yes, even for 5000 tons it's not workable. But it was a good movie. I liked it a lot. I like green foliage and exotic locations and panoramas. Beautiful. And what's her name and Jake-my-jake shoulda' locked their hair up before sex ... that woulda' been hot !
then you can show with the Stefan–Boltzmann law that, with a double sided carbon radiator (which has an emissivity of .98, and can operate at 3500 K), you'd only need a radiator the size of a square 250 meters on one side. That's still like 4-5 times bigger than the ones shown in the film, but remember, radiators aren't needed at all in theory if the heat is carried in the exhaust, which is heavily implied. They're obviously there due to a design imperfection.
@SeersEnlightenment Unfortunately, the annihilation of antimatter gives off gamma rays that can't be controlled or directed. That's what would melt the engine instantaneously ... in the first millisecond of operation.
@Bantokfomoki "can't be controlled or directed" isn't exactly proven. Though, I haven't even a clue as to what could be done about this, so I guess you win :P. Maybe the annihilation event occurs outside of the ship, with the engines only being there to propel the fuel away? The charged particles could still possibly push a magnetic field. Or maybe the gamma rays could be redshifted to something that could be reflected?
@SeersEnlightenment The annihilation is clearly within the engine compartment (from the deleted scene of Venture leaving Pandora). When a photon is the right wavelength an electron is raised up to a higher 'orbit'. Then it falls back and re-emits a photon (reflection). A Gamma ray is a photon but too energetic. It annihilates structures and creates a plasma. Your engine is turned to plasma instantly ... given the rate of antimatter posited.
@Bantokfomoki Well, in theory all you need is around 1-2 kg of antimatter per kg of ship. That's not exactly useful in determining if antimatter would work in practice or not if a reasonable supply is readily available. The deleted scene doesn't show very much either - the ship is mostly obscured by the exhaust. Not conclusive enough to tell where the annihilation event actually occurs. Given the ships length, it could easily be a kilometer away from the engine.
@SeersEnlightenment The interaction must occur in the engine compartment because of the displayed nozzle effect, i.e. if it occurred outside of the engine it would spread out uselessly. And if it's IN the engine ... the engine is toast ... immediately because of gamma ray production.
@Bantokfomoki Meh. The isv is silly and no one disputed that. But having the annihilation event occur hundreds of meters away from any part of the ship and having a sort of magnetic "sail" to obtain thrust from the charged particles might work. The intensity of the gamma rays would be greatly reduced as described by the inverse square law. This has its own glaringly obvious problems, but it's silly to jump to conclusions so early :p.
@SeersEnlightenment I don't agree with you at all. If someone says ... 2+2=4 ... can you dispute it and say, "It's silly to jump to conclusions so early"? With respect to the laws of physics as they are presently understood ... there is no possibility of going to another star in say ... 10 years travel time ... maybe in 2000 years travel time for a near star ... maybe ... but never in just 10 ;o)
@Bantokfomoki Heh he heh...But 2 + 2 doesn't always equal 4. Check out fusion; the mass of matter left after a fusion event is less than the starting mass. 2+2=less than 4. When you say 2,000 years to reach the nearest star you are imposing an ultimate speed limit of 480 miles/sec on humanity. That's a ridiculously low speed even for fusion powered ships. It amounts to saying the fusion efficiency is going to be less than 1/10th of one percent. I know we can do better that.
@1DanConnors What I mean by 2000 years is ... it's way beyond a human lifespan to get to Alpha Centauri ... by ANY MEANS WHATSOEVER (within the constraints of the conservation laws). I'd be real surprised if we could reach there in, say, 250 years (with good weather all the way).
@Bantokfomoki 250 years means app. 1/60th c or 3,000 miles/sec. The ultimate performance of a fusion drive at 100% efficiency, with 2 stages each way, is .23 c, so a fusion rocket reaching .017 c would have an efficiency of only .54%, less than one percent. I believe your figures and prognostications are extremely pessimistic. I believe that humans will someday routinely travel at .1 c, and the zone of Human control in 6,000 years will be 1200 light years in diameter containing 8 million stars.
@1DanConnors I think they will travel at .1c also ... but not by conventional means (fusion or antimatter). By "human control" do you mean we're going to conquer militarily all the other people out there? ;o)
@Bantokfomoki I'd be surprised if we encounter any intelligent life within 600 light years of us. As you know from your other columns, I don't believe in flying saucers flown by aliens. But let's assume there are 20 alien cultures capable of IS travel in the galaxy. the nearest one would then be 11,180 light years away (by the law of averages). I recall from my grade school days being made to write on the board 50 times, "Men will never fly to the Moon." I mean the zone inhabitted by Humanity.
@Bantokfomoki Getting a bit knitpicky aren't we? I was arguing, of course, that men would go to the Moon. I have an interesting figure for you. The Saturn 5 rocket's first stage generated 950,000 times the energy of a Nimitz class aircraft carrier, but no one finds that impossible. If the SV engines had not been protected by regenerative cooling they would have melted and exploded in about 1 second. The figures you have tossed out in this clip prove nothing beyond the fact that the Avatar ship..
@Bantokfomoki as rendered in the movie won't work. Indeed I don't think AM as a fuel will ever be used. Too dangerous. Fusion bombs are with us already, and if they are used with only 20% efficiency, and 2 stages, we can reach .1c. You have not demonstrated any violations of the laws of physics; you have only shown heavy engineering problems to be solved. What type engine can withstand a 13 Kton bomb blast per second? Answer: a pusher plate 800 feet in diameter.
@1DanConnors They aren't "heavy engineering problems" ... they are "impossible" engineering problems. At some point, engineering problems become irrational to pursue because they afford no solution in the real world.
@Bantokfomoki You kind of remind me of the physics professor during World War 2 who told his students there was no way a man made device could exceed the speed of sound. As he spoke, in the distance, could be heard the sound of antiaircraft guns at practice, firing their projectiles at 3 times the speed of sound. Other ultraconservative physicists argued travel to Luna was impossible because no fuel had a Vexh higher than escape velocity, and no rocket could exceed its own exhaust velocity.
@Bantokfomoki A vehicle which reaches .1c, using propulsive energy in excess of the kinetic energy it attains doesn't violate any of the laws of physics. A fusion rocket operating at 20% efficiency doesn't violate any laws of physics. Pointing to an engine and saying there's no way in hell it or any conceivable engine can dissipate the energy of a 13 Kton bomb blast every second doesn't make it so. All of your "impossibilities" can be circumvented by enlarging the engines and reducing thrust.
"All of your "impossibilities" can be circumvented by enlarging the engines and reducing thrust."
What is impossible is getting there in a human lifespan. THAT is not possible ... in principle.
It's a technological impossibility ... not a logical impossibility. Why don't you make a video, yourself, showing how and why it's possible to get to Alpha Centauri in 30 years or so (within the constraints of the presently known conservation laws)?
Checked the ol' wikipedia : 139.6 MeV*c^-2 for the charged ones.
OldDirtyRatbastard 1 day ago
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axmed1987 1 week ago
It's impossible for any type of material having a significant amount of weight to it to make the long journeys to other worlds in a time frame that would be convenient. One who have to become converted to light to bridge the distance. Or one who have to travel astrally. There is no metal or ship that could survive the rigors of faster than light travel. We'd have to become light to traverse to other galaxies.
knossis1 3 weeks ago
@knossis1 You're neglecting relativity. For the people on board, the journey could actually be quite short depending on how close you approach the speed of light. And it's not impossible at all assuming you can find a suitable way to accelerate..
Prospekt0r 1 week ago
@Prospekt0r I get your point, but barring science fiction and dilithium crystals,(dilithium is also the scientific name for a molecule composed of two lithium atoms) we have yet to find a suitable way to get anywhere close to the speed of light. My research has led me to belive the ancients traveled astrally, which would be a lot more effecient & practical. But I like u believe anything is possible given time. So who knows, in the future we may have warp engines and what not.
knossis1 1 week ago
@knossis1 If you're looking to get to alpha Centuri, you don't even need to get close to the speed of light. 10% is sufficient and the journey would only take around 40 years. Achieving such speed is possible with current technologies (no anti-matter needed). If we want to go further we just have to find a way of mass producing anti-matter. Worm holes and warp speeds are theoretically according to general relativity as long as we have a negative mass (as of yet no such thing has been found).
Prospekt0r 1 week ago
Yeah, the Venture Star runs a completely ridicuolous accelleration. But IIRC if the acc is cut to 1/100th (travel time ~60 years) it's a lot less farfetched.
When I did the math for a antimatter RAIR/Ramscope I was planning to use for a novel I got to Alpha Centauri in about 80 years with only ~15% of the ship's mass being AM fuel and only ~20 square miles of radiators for the 100,000 ton craft.
Sabelkatten 1 month ago
Perhaps the ship manipulated the space-time continuüm by pushing away baryons or perhaps the ship concentrated the amount of dark energy around itself. It's a movie, everything is possible.
F19991 1 month ago
have you got the most boring voice on Earth or Avatar
hutchison82 1 month ago
After the funeral of his brother and the cgi forests...the space ship scene is classic....the thing is i dont think anyone can better stanley kubrick
Ke1ithLemon 1 month ago
How do you know it is 100000 metric tonnes? The craft looks much lighter, like around 10000 metric tonnes? And keep in mind that the craft does have a solar sail as well.
LouistheHedgehog 1 month ago
@LouistheHedgehog I later revised my estimate to a million tons ;o)
Actually the mass doesn't matter ... to get to .7c requires a proportional amount of antimatter.
I just saw Cameron's little book about Avatar in Walmart. I checked to see if he gave a mass for the Venture ISV ... still ... no mass. The absence of a stated mass is like selling off all the steel from the World Trade Center ... they're hiding something ;o)
Bantokfomoki 1 month ago
@Bantokfomoki I agree that a six year trip time with an antimatter rocket is impossible, but trip times less than a human life time would definitely be feasible. A 40-50 year transit time would only require a velocity of about 10% of c.
SkrillToss 2 days ago
@SkrillToss I don't think that the trip is feasible in less than 1000 years with a huge flotilla. I have zero confidence in any kind of short trip at all. If you thoroughly examine the subject, you will just get more and more pessimistic.
Bantokfomoki 2 days ago
@Bantokfomoki I seriously can't believe this. You have repeated time and time again that this design was impossible because of the virtual impossibility to reflect or at least redirect the gamma rays produced by the engine... And NOT ONE person picked out that they don't need to be. You're right, an antimatter engine isn't 99.9% efficient, 44% of the reactants' mass energy ends up as gamma rays. Where you're wrong is that you assume that these gamma rays interact with matter in the same way...
OldDirtyRatbastard 1 day ago
@OldDirtyRatbastard Gamma rays must be produced in pairs (linear momentum conservation). One goes out the ass end (the propellant) and the other one MUST be absorbed by the front of the engine nacelle ... or ... the reaction produces no thrust. Get it? The gamma ray can't push the ship if it doesn't hit it (action-reaction). If a large proportion of the gamma rays hit the body of the ship ... you're toast.
This ship [as designed] would last less than 1 second if you started the engine.
Bantokfomoki 1 day ago
@Bantokfomoki than lower energy photons. Well, they don't. Light at these high energies has an attenuation coefficient for materials normally opaque to it, and that coefficient goes down as the photons' energy increases. The rays released by proton-antiproton annihilation happen to be the most energetic there are outside of galactic nucleus events, meaning that nearly every material is transparent to them : they don't induce heat and don't destroy atoms, they just zap through into space.
OldDirtyRatbastard 1 day ago
@Bantokfomoki Now, let me say that i abhor the movie, but that spaceship is everything but silly. It was studied in depth as a concept, way before the movie's idea even existed, by Stanford university professors who found that the only impossibility preventing it from reaching over 60% c in a few years of acceleration was the antimatter requirements in the thousands of tons. The study found out that the radiators have no heat to dissipate from the engine, they actually only serve to...
OldDirtyRatbastard 1 day ago
@OldDirtyRatbastard Where do you get the energy to refrigerate the tungsten? The refrigeration would be a function of the fuel use ... so ... you'd need lots of refrigeration. (And by "lots" I mean we don't have a word in the English language to express such a large amount ;o)
Bantokfomoki 1 day ago
@Bantokfomoki refrigerate a tungsten shield which is purposely placed in the exhaust to cast a "shadow" within the gamma rays, protecting the crew compartment as well as some EM perturbation-sensitive electromagnets. You can be sure that these people did more calculations about the feasibility of this ship than we probably ever will, i can send you a link to the full university paper if you want. Intersestingly, the shield would get so hot that the light it would radiate would produce thrust...
OldDirtyRatbastard 1 day ago
@OldDirtyRatbastard I thought you said gamma rays just zip through everything harmlessly ... so ... why does the crew need to be protected? ;o)
I agree that the people who did the calculations did more than me. They too found the scheme unworkable ... therefore ... they neglected to mention the mass of the ship ;o)
I call this what it is ... scientific fraud. But it's a harmless fraud. So, I don't really care. I liked the movie very much.
Bantokfomoki 1 day ago
@Bantokfomoki which is a (very indirect, but feasible) way of converting the gammas into usable thrust.
OldDirtyRatbastard 1 day ago
@OldDirtyRatbastard No, it wouldn't generate thrust. The heat given off as photons would go in every direction and produce no thrust at all.
Lastly, if a gamma ray hits something ... it destroys it. If it doesn't hit something, it's useless as a propellant. If enough gamma rays hit anything at all ... it disintegrates.
End of story.
Thanks for taking the time to post here.
Bantokfomoki 1 day ago
@Bantokfomoki The visible photons can be collimated by ordinary mirrors, producing some thrust.
Indeed, it destroys, IF it hits. And a gamma ray with enough energy has too small of an amplitude to hit anything less dense than tungsten. The Stanford spaceship had a reaction chamber built of beryllium, and their calculations proved that it would whitstand several grams of matter/antimatter annihilating per second thanks to transparency.
Now, it seems that we've had a misunderstanding. I've never
OldDirtyRatbastard 1 day ago
@Bantokfomoki said that the gamma rays could be used as an useful propulsion system, i gave the 56% efficiency because these 44% of gamma rays are, for all intents and purposes, useless. But proton-antiproton annihilation produces charged and massive pions in addition to gamma rays. That's what used as propellent.
The crew needs to be protected because humans are not made of bulk material. Even a single atom knocked out by a single gamma photon in any of one's cells can end up as cancer.
OldDirtyRatbastard 1 day ago
@OldDirtyRatbastard Using pions as propellant significantly reduces the efficiency of the engine. You're gonna' need a lot more antimatter. Ramp up that fuel ratio.
Bantokfomoki 1 day ago
@Bantokfomoki Oh, you are right about that. The film version is a perversion of the original which is like a space rat-rod : bare bones. The engine is a single toroidal coil, the shields are not the stylised fins of the movie but a small tungsten plug on the poymer thether, the crew compartments are disproportionately small, the radiator is an invisible cloud of magnetic fluid droplets doubling as a dust shield, and the power systems are hidden around the cylindrical fuel tanks.
OldDirtyRatbastard 1 day ago
@OldDirtyRatbastard If you throw out one pion ... another one has to hit the front of the engine nacelle to produce thrust. This produces damage, heat, annihilation. You can't control the entire solar output to the earth within the Venture's engines. It's so ludicrously impossible. A Tsar Bomba every second for millions of seconds?!
Just because a man is a scientist does not mean he's an honest man. The thing is a "paid for" fraud. And, as I said, I don't care ... the movie was just swell ;o)
Bantokfomoki 1 day ago
@Bantokfomoki material annihilated to get their lousy 1.5G acceleration.
I actually read that paper, and the guy's conclusions are mathematically correct and pretty much indisputable. There's something called "peer review", you can't pay scientists from universities all over the world to agree with a "fraud", unless it's a matter of interpretation. And this really, really isn't.
The bad efficiency is also accounted for in the general effective exhaust velocity for the rocket, they found 0.58c...
OldDirtyRatbastard 1 day ago
@Bantokfomoki from 0.94c for the pions themselves.
OldDirtyRatbastard 1 day ago
@Bantokfomoki so even though the gamma rays would pass through harmlessly, there's still a chance they's give someone a tumor during the 6+ years of acceleration.
They did not ignore the mass of the ship, they calculated a fuel to mass ratio of 22 to 1. The payload was set at 400 tons, requiring 8800 tons of antimatter. The ship is only very long because the crew quarters are dragged at the end of a 10km thether. This distance from the engince minimises the amount of gamma rays reaching the...
OldDirtyRatbastard 1 day ago
@OldDirtyRatbastard Look at the ship in the movie. Do you really think that weighs in at ONLY 400 tons?! My conservative estimate was 100,000 tons. I later revised my "mistake" to 900,000 metric tons. Hmmmm .... did they use a shrink ray, ya think?
Bantokfomoki 1 day ago
@Bantokfomoki Now that actually looks like it weighs 400 tons empty, but it was too ugly for the director's needs.
Nope about the pions, you are forgetting that the enormous amounts of energy imparted to them goes to their speed, but their rest mass remains small (if i remember right, around 100 MeV*c^2). This means that they have little momentum and can be redirected into a working exhaust by a simple magnetic nozzle. On the other hand, the thrust is crappy, which is why they need a lot of...
OldDirtyRatbastard 1 day ago
@Bantokfomoki shields, diminishing the need for refrigeration.
You could imagine many things a generator for the heat pumps... Solar panels, a magnetic "turbine" in the charged particle exhaust, an array of fuel cells... Anything that doesn't produce too much heat.
OldDirtyRatbastard 1 day ago
The Venture Star uses magnetically confined antimatter/matter annihilation. The "unobtainium" is supposedly a room temperature superconductor, making the required magnetic field much easier and cheaper to make. Once the engine is fired at about 1 g, it accelerates for about 3 years, then fires breaking engines. I hate it when people who aren't from scientific backgrounds try to lecture on science and engineering. Not only is this possible, it's probable in the next 300 years.
golthimere 1 month ago
@golthimere There is no known way of containing an antimatter annihilation. The product of such an annihilation is primarily gamma rays. They cannot be redirected by a magnetic field or mirror. Whatever they hit ... they destroy. By conservation of linear momentum at least two gamma rays MUST be produced going in opposite directions. One of them must therefore hit and ionize an engine atom. Goodbye engine (in the first nanosecond).
You need some more scientific background ;o)
Bantokfomoki 1 month ago
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SimKoning 1 month ago
This has been flagged as spam show
@Bantokfomoki Actually, if we ever figure out how to produce or capture monopoles we would probably be able to produce all sorts of exotic materials. These might include mirrors capable of reflecting gamma rays, hyper dense matter and virtually indestructible materials. This is obviously speculative, but within the context of the of the film it's not that much of a stretch if you replace "unobtanium" with "monopolium". It's certainly less far fetched that reactionless propulsion..
SimKoning 1 month ago
We would also be able to create the flying saucers you are so fond of ; )
SimKoning 1 month ago
Maybe the engine power/excess heat can be contained by the unobtainum?
LouistheHedgehog 1 month ago
@LouistheHedgehog Well, yes ... it could do that. Unobtanium can do anything. That's why they call it "unobtanium". ;o)
Bantokfomoki 1 month ago
@LouistheHedgehog Well, yes ... it could do that. Unobtanium can do anything. That's why they call it "unobtanium". ;o)
Bantokfomoki 1 month ago
@LouistheHedgehog Well, yes ... it could do that. Unobtanium can do anything. That's why they call it "unobtanium". ;o)
Bantokfomoki 1 month ago
@LouistheHedgehog
see my post above.
SimKoning 1 month ago
Oh and by the way, I'm not dissing on you man. Your video brings fourth pretty good information. Antimatter engines may not be impossible though, but pretty impractical for a lot of other reasons than what you stated I admit.
yemo34 1 month ago
@yemo34 the worst part about antimatter is ... we don't have any. And ... to make some would require more than the amount of energy we'd get out of it (2nd law of thermodynamics) ... even if we could make it
Bantokfomoki 1 month ago
Antimatter rockets would probably only be practical in hybrid systems that use it only to "catalyze" fusion reactions. They might become feasible for a civilization that can harvest the solar out put of several stars, but they would probably need some kind of FTL transit system like traversable wormholes which are even more unlikely/speculative. And if monopoles actually exist, and can be created, antimatter rockets would become obsolete anyway.
SimKoning 1 month ago
Another possible application would be a Bussard ramjet that uses antimatter as fuel and interstellar hydrogen as the reaction mass. But, then you still have the problem of boosting the ramjet up to about 1% to 6% c. before the ramjet would actually work. This might be possible with a large enough laser sail.
SimKoning 1 month ago
@SimKoning The Bussard Ramjet idea has been abandoned because you lose too much energy scooping up the hydrogen which is not moving with you.
Bantokfomoki 1 month ago
@Bantokfomoki There are modification of the concept such as the RAIR, as well as a few others. They usually involve reducing the "drag" by not slowing down the hydrogen atoms for fusion, and instead use antimatter to annihilate the hydrogen as it passes through the rocket. So, it's not completely dead. Also, some of the criticisms of the concept depend on some assumptions. We are obviously hundreds of years away from testing these various concepts.
SimKoning 1 month ago
There are some GUTs that involve exotic forms of matter and proton decay that might make relativistic rockets, unimaginably strong/reflective materials and even non conservation violating reactionless drives possible. I wish Avatar was set much further in the future, and I wish he had come up with a more plausible form of exotic matter other than "unobtanium". Based on the teaser, It looks like Niel Blomkamp's next movie Elysium will be a more realistic take on interstellar travel.
SimKoning 1 month ago
@SimKoning Keep in mind that this ship actually does use a fusion/anti-matter hybrid system.
LouistheHedgehog 1 month ago
@LouistheHedgehog It doesn't matter if it's a hybrid ... it still won't go to Alpha Centauri in less than an human lifespan. That's my whole point here. You can go there ... provided you are willing to spend a few thousand years in transit. Any mechanism conceivable can't get there quickly if the laws are physics are valid. It's technologically impossible. I've done the math and it's not even close to possible.
Bantokfomoki 1 month ago
his monotone is killer
ThaWasian 1 month ago
I doubt it is impossible for space travel to exceed our modern parameters. Avatar takes place in the future, and not the near future either. And how can we even say that are laws of physics wont be drastically altered by that time. Science had many paradigm shifts, extreme ones. Like how relativity brought Ideas such as time dilation into play. In essence this IS time travel. An Idea someone like Newton would laugh at. Uttering the word impossible measures a degree of cultural arrogance.
yemo34 1 month ago
@yemo34 You should also keep in mind that Newton's laws are still valid to day within a certain scale range, it's only when you get to the macrocosmic and microcosmic that they need to be expanded upon.
SimKoning 1 month ago
@SimKoning As you can see in the above video, I agree. I used them to calculate that interstellar travel using a reaction engine ... of any kind ... will never get us to our nearest neighbors in less than a few thousand years.
Bantokfomoki 1 month ago
@yemo34 Science has paradigm shifts ... nature doesn't. It's just there. The laws of physics are the same in the Avatar scenario as they are now ... hence, the ship is impossible.
Bantokfomoki 1 month ago
Science is the process by which we understand nature. There are no written down rules that say how nature works, anywhere. Scientists take evidence, and formulate theory's on how it "might" work. We are limited by our tools and senses. Supersonic flight, nuclear weapons, and computers were not possible 150 years ago because of those reasons. For all we know the ship could have force fields on it's engines.Sounds like fantasy now, but at one point so was a moon landing. It's not impossible.
yemo34 1 month ago
Bantokfomoki 1 month ago
@yemo34 He's wrong and he knows it. What he does is refuse to listen to those who have proven him wrong. It's sad really. He will continue to run his pathetic little site for the rest of his life. Let him have it.
1DanConnors 1 month ago
The ship in Avatar is the most realistic starship ever put on the big screen: it's based on Dr. Charles Pellegrino's and Jim Powell's Valkyrie concept, which if feasible, would reach a maximum velocity of 92% c. There is also a version with a mass ratio of 1.5 that would reach 10% c. Cameron's version is actually a light sail/fusion/antimatter combination. the primary flaw is not so much the antimatter rocket, but the massive laser battery that would be needed to propel it up to 70% c,
SimKoning 1 month ago
I'm a little skeptical about you mass estimate. You are comparing a machine that would be made mostly of ceramics and extremely light, stronger-than-steel materials such as carbon nanotubes with an armored aircraft carrier. The Valkyrie concept is one of the lowest mass starship designs out there because the rockets are placed in front of the crew module. There are several other plausible rocket designs out there that would reach a significant percentage of c.
SimKoning 1 month ago
If I'm not mistaken, your skepticism in regards to "the standard model" seems to be rooted in the fact that you think UFO flying saucers are real. I'm a little stumped as to why you are skeptical of heavily tested hard science, yet you have concluded (based on anecdotes and blurry photos) that flying saucers powered by reactionless drives are real. It's like believing in fire breathing dragons before concluding that biologists "got it wrong" to make room for your presupposition.
SimKoning 1 month ago
@SimKoning The evidence for the reality of UFOs is ... to put it mildly ... overwhelming. Because they arrived here from there ... and behave so cavalierly ... I must assume that it's relatively easy for them to get here. Ergo ... the supposition that the conservation laws can be overcome.
Bantokfomoki 1 month ago
@Bantokfomoki I think you are begging the question: the evidence that the laws of thermodynamics and other branches of physics are correct is *far* stronger than the evidence that UFOs are actually alien visitors. There is about as much evidence for saucers and Greys as there is for Bigfoot and ghosts; that is to say it is in the form of anecdotes and questionable photos/video.
SimKoning 1 month ago
However, I do find it hard to believe that aliens have not been here in the form of probes of some kind. The Fermi paradox combined with the age of the galaxy suggests to me that we have been visited a few times, but it could have been only few cases, by several different forms of life over millions, if not billions of years. After all, macroscopic complex life has only been around for about 600 millions years out of 4.6 billion year lifespan of this planet.
SimKoning 1 month ago
Then when you also consider that our species may not be all that interesting to an intelligence that may have been evolving for a billion plus years, combined with the fact that we have only been around as a species for a little over 100,000 years, I can't help but suspect that we are little more than ants on the side of the road.
SimKoning 1 month ago
@SimKoning No... we are special. They've been waiting for us. Thinking beings are all there is to wait for. I suspect that they have had cities on the earth in times past and have moved off-planet to let us evolve.
Bantokfomoki 1 month ago
@Bantokfomoki Interesting speculation, but I'll be the first to admit that that's all it is. Asserting that aliens think we are special is question begging, because you have yet to demonstrate that aliens even exist in the first place. I reject the notion that UFOs are proven to be alien, because I've looked at the evidence, and I find it no more compelling than ghost sitings. So, ultimately, we are left speculating about the Fermi paradox.
SimKoning 1 month ago
@SimKoning We differ here. I think it's like "dodge em" cars out there ;o)
Bantokfomoki 1 month ago
@SimKoning I completely agree that the evidence for the conservation laws is much greater. Up until a decade ago I would have bet my life on them.
The evidence for UFOs is about 1000 times greater than for Bigfoot however. Given that "they" are here ... I have to postulate some way to get round the conservation laws. So ... I did.
It cost me exactly nothing to look into and think about the subject ... just my time.
Bantokfomoki 1 month ago
@Bantokfomoki You say it's a thousand times greater, yet I see nothing other than anecdotes and blurry photos/videos. There may be *more* people claiming to have seen UFOs than Bigfoots, but using that as an argument is little more than making an appeal to popularity. The quality of evidence must be considered. Also, there are reactionless drive solutions that do not involve violating any of the conservation laws, such as various warp metrics.
SimKoning 1 month ago
@SimKoning The mass is irrelevant. To get to .7c you need about twice that mass in antimatter to get to the designated speed. This is NOT EVEN CLOSE to possible. It's orders of magnitude off.
Bantokfomoki 1 month ago
Comment removed
SimKoning 1 month ago
Antimatter aside, we should not rule out breakthroughs in technology that we can barely even imagine; we are talking about hundreds, if not thousands of years in the future here. For all we know, an advanced civilization may develop exotic forms of matter and energy such as monopoles and/or negative energy, which in turn could lead to rockets capable of high relativistic speeds, and in the case of negative energy, some form of reactionless propulsion.
SimKoning 1 month ago
Then there is the fact that human lifespans will probably be measured in centuries by that point, and, for all we know, our descendents may evolve to be partly or entirely mechanical.
SimKoning 1 month ago
This has been flagged as spam show
@SimKoning While the rocket in the movie has serious problems, an antimatter rocket is not an impossible thing. The more realistic concepts involve ships that are essentially a big rocket (and little else) pulling a crew module on a several mile long "string". The real problem with the one in the movie is that the radiation would have killed the crew, primarily due to the fact that the "string" pulling the crew is way too short.
SimKoning 1 month ago
@SimKoning No ... nothing will make any difference ... if ... the conservation laws are eternally valid.
Bantokfomoki 1 month ago
@Bantokfomoki Since I'm not a physicist, I'm forced to side with experts in the field (NASA researchers for example), which seem to think that advances in technology such as the VASIMR plasma rocket may lead to rocket systems that you believe to be impossible. The Atomic Rockets page has a rather long list of plausible rocket concepts ranging from antimatter, fusion, antimatter catalyzed fusion, antimatter nuclear pulse, laser sails, etc.
SimKoning 1 month ago
It might be worth your while to take a look at least. If nothing else, it's an enjoyable read for fans of Hard SF.
SimKoning 1 month ago
@SimKoning You're right. The guy's error is pointing to the way too small engine in the movie & pointing out it can't contain the tremendous heat generated. True; but we can make changes. We are trying to achieve a velocity of app. 1,000 times what we can achieve with our best NERVA thermal nuke engine. That is 7,000 miles per second. With 2 stages this is 14,000 miles/second. The heat energy we must handle will be 1,000^2 = 1,000,000 times the heat energy a NERVA engine would produce for the...
1DanConnors 1 month ago
@SimKoning ..same thrust. Step 1: decrease thrust ratio of the engines. The NERVA, in larger sizes has a thrust/weight ratio of 50 to 1. We decrease that to 1 to 20. This gives us a thousand fold increase in our ability to handle heat. Not enough. Now we reduce overall thrust. For NERVA we aimed for 1.3 g's. Decrease that to .001 g's. we get a 1300 times reduction. Our total now is a 1.3 million increase in our ability to handle heat as compared to NERVA. We are there; the stars are ours.
1DanConnors 1 month ago
@SimKoning I don't 'believe' that such rockets are impossible ... I KNOW that they are impossible ... by way of the conservation laws. The laws THEY are breaking with plasma rockets aren't the laws of physics. Rather, they are local, state and federal statutes concerning fraud ;o)
Bantokfomoki 1 month ago
@Bantokfomoki I'm confused by what you mean by fraud: the VASIMR rocket actually exists and has been tested. The whole point is to develop a rocket that uses superheated plasma while avoiding that nasty problem of your rocket melting. Regarding the energy needed for the production of things like antimatter, that will depend on the amount of energy we are able to utilize in the future. We haven't even reached 1 on the Kardashev scale yet.
SimKoning 1 month ago
@SimKoning It's a fraud if they say it can be used for interstellar travel. If they want to use it withing this solar system ... go for it. There are lots of viable things to do in our immediate neighborhood.
Bantokfomoki 1 month ago
@SimKoning The problem IS the anti-matter engine. It's totally unfeasible. Absolutely ... unequivocally ... unphysical.
Bantokfomoki 1 month ago
@Bantokfomoki Actual rocket scientists seem to disagree with you. Charles Pellegrino, the scientist that actually designed that rocket for Cameron (they are friends I think) thinks a rocket capable of relativistic speeds (10% to 70% c) will be feasible provided the fuel can actually be manufactured, which of course is (to say the least) the real problem. The technologies that may lead to such a rocket are already in development-
SimKoning 1 month ago
Antimatter has been created contained in very small amounts, the Vasmir plasma rocket, which utilizes a magnetic bottle and "nozzle" to propel charged particles is already being developed by NASA, super light stronger than steel materials such as carbon nanotubes have already been invented. Assuming that this will not lead to much more advanced rocket systems may be as shortsighted as thinking that aircraft technology would have stopped evolving past WW1 fighter planes.
SimKoning 1 month ago
Avatar fails as a movie and it fails at much of the physics, biology and pretty much everything else.
Ryagful 1 month ago
no offence but youve got the creepiest weirdest voice ever.
manwithouthat44 1 month ago
So, when are you going to write your theoretical essay of the flaws in space propulsion concerning the rockets of the Flash Gordon serials?
luis6079 2 months ago
i understand the philosophy behind your thoughts but avatar is just a fiction how can someone waist time to be serious about a beautiful movie witch was made by human through vision (fantasy) by human. that can open doors to read about many subjects -space travel, physics,antimatter, infinite space,propulsion engines so on so forth,but this person have to get out from the dream world i think.
joeyka121 2 months ago
I'm pretty sure there are methods to get to Alpha Centauri within a human lifetime. Not possiblle until into the next century, but still plausible within our current understanding of physics. If you can average 0.1c, then we get there in 42 years. We could manage that with antimatter engines, or even antimatter catalysed fusion.
TehOrkyMan 2 months ago
it's not just anti matter, the ship in avatar(which, by the way, is more accurate than most any other sci fi ship specifically star trek/star wars) used a photon sail and laser propulsion. im no good at science, but please take that into account.
chingchombuela 2 months ago
@chingchombuela I did ... and it still doesn't matter. The whole idea is untenable.
Bantokfomoki 2 months ago
@Bantokfomoki well, it is fictional story(and my favorite) and the ship had to work for the plot, so can you blame them? at least it more sense than most sci fi ships.
chingchombuela 2 months ago
@Bantokfomoki i also agree with you about physics, by the way, they may not be totally correct.
chingchombuela 2 months ago
@Bantokfomoki how does a comet travel and does it has fuel or h bomb on it, it doesnt but keep moving. Think about it.
stanchiam 1 month ago
totally missed the point. a comet, LIKE THE EARTH, is simply ''falling'' in the gravity of the sun. its falling in an elliptical orbit, and just to be clear, there is energy involved. right now, gravity is applying energy to you and me and puling us down. i don't know how much, but a planet or comet orbiting a sun has a lot of energy.
Ryagful 1 month ago
Two things here. (1). the ship venturestar looks more like a 100 years travel design, so we should perpare for a 100 year round trip journey at a attainable speed. (2). I believe the distant caculated by scientist about light distance are inaccurate, ( WHY? ) we do not possess a device thank can measure over the great-great almost impossible distance. If we mis-calculate here, we will over-shoot our destination by ???? which = death!
legendhunter47 2 months ago
@legendhunter47 The distances to the nearer stars are calculated with a great deal of accuracy. It's a trigonometric exercise where the distance from Earth to the sun forms one side of a VERY long triangle. By measuring the star's angle from the horizontal at a given time on one day, then measuring its angle 6 months later at the exact same time, the length of both the base and hypotenuse can be determined very accurately. They are planning a probe to multiply that baseline by a factor of 40.
1DanConnors 2 months ago
u have no life
az015 2 months ago
@az015 Thank you. It's refreshing to see such intellectual depth in a mere comment field ;o)
Bantokfomoki 2 months ago
@Bantokfomoki You're welcome
az015 2 months ago
One of your best all time movies?
WTH man? This was a stinking pile of directorial and scriptwriting masturbation. It systematicall abused us from start to finish, and as far as I am concerned is by far the worst movie ever made - even worse than "Hollywood Cowboy" and "Sasquatch".
M0b1u5 2 months ago
@M0b1u5 Yes, but you're overlooking the best feature ... it's GREEN !!!
Bantokfomoki 2 months ago
@JAMAC08
I think both show promise. We need to learn a lot more about space-time in order to make them work, but I think that eventually we will develop a warp drive based on similar concepts. But unless a scientific miracle occurs soon, I doubt FTL will exist within this century. I think though, that antimatter is the best hope we have for the next century for large starships. But there are Von Neumann probes, they seem to be the most practical. Look them up, they are very exciting.
sniperboi96 2 months ago
@sniperboi96 You don't have to worry about anti-matter drives in the next century ... you only have to worry about how to sharpen a good "digging stick" to get at roots to eat. You need to know how to "flake" rocks to make spear points ... stuff like that. Forget about interstellar space travel for at least another 2000 years. In the next 1-2 centuries more people will die on the earth than ever before or ever after ... regardless of what anyone thinks, does or says about "Avatar".
Bantokfomoki 2 months ago
It is possible to go to Alpha Centauri in a human lifespan if we were able to go a mere 10% of the speed of light. That is possible with an anti-matter drive. I like people who say "it cannot be done" because it makes others who dream and truly innovate able to push forward and do it, much to the dismay of naysayers. Trans-atlantic cables carrying signals with our voice was once deemed impossible, as was supersonic speeds. Thank you, you've motivated my to prove you wrong.
eskercurve 2 months ago
@eskercurve Any examples you note about people overcoming the "naysayers" are about 3 orders of magnitude easier than interstellar space travel. You site a 1,4,3,6,2 magnitude problem while interstellar space travel is on the scale of 3000, 5000, 2000 etc. Dump a cold bucket of water over your head. You're going nowhere unless you go REAL slow ... or ... find an end round the conservation laws.
Bantokfomoki 2 months ago
What about Alcubierre metric and the discovery of Dark energy? We could harness enough Dark energy and create a WARP bubble
JAMAC08 2 months ago
@JAMAC08 What about just saying "abracadabra"? That must surely be worth looking into because if it worked ... it'd be really cheap.
Bantokfomoki 2 months ago
Ok now I know u definitely lied u arent a physicist u should talk to mechanical engineers like myself and physicist who are working on space propulsion right now. U do know what ur talking about but ur just not current.
jasonsacrifice1 2 months ago
@jasonsacrifice1 There is no "current" in the laws of physics. They are eternal (now and forever). Or ... they are invalid ... eternally.
Bantokfomoki 2 months ago
and the statement you made was grossly incorrect
jasonsacrifice1 2 months ago
and you are also forget emerging technology
jasonsacrifice1 2 months ago
@jasonsacrifice1 I haven't forgotten anything ... YOU'VE ... forgotten the laws of physics ... IF ... you ever knew them ;o)
Bantokfomoki 2 months ago
u should always be careful saying impossible. because so call impossibilities have turned out to be possible and we dont have a complete knowledge of physic its best to say unlikely but we might be able
jasonsacrifice1 2 months ago
@Bantokfomoki
Typo: take the I out of the last sentence.
sniperboi96 2 months ago
@Bantokfomoki
Thank you for the video, it was very informative and well thought out. You had some valid points. However, I do believe that antimatter is the key to interstellar travel. But I doubt that we will be able to get starships above .5c (besides electromagnetically accelerated nanoships). I have been trying to design an antimatter rocket, and I your points have made me rethink some aspects. Thank you.
sniperboi96 2 months ago
let's ignore antimatter problem for a bit here. Say we use reaction engine. Is it possible to contain a massive explosion needed to propelled the ship to a necessary speed within our current technological capacity?
lanunselat 2 months ago
@lanunselat You mean an engine like a regular rocket? No. That can never propel a ship to significant fractions of light velocity because of Tsiolkovsky's rocket equation. The amount of fuel required is way, way, way beyond technological possibility.
Containing the explosion isn't the problem ... it's hauling the fuel needed to propel the fuel. That's what the rocket equation is about. It's simply the law of linear momentum conservation as applied to space travel.
Bantokfomoki 2 months ago
2 things that prove your thery about never going some where far off in a human life span. Well before I say this one of these was not discovered untell 2011. CRYOGENICS! and that one new element german scientise found that can go faster than light and is carriable
IsaacD39 2 months ago
Chuck norris can reach alpha centauri in one step.
Elitetank87 2 months ago
also... your aircraft carrier to ship ratio is inaccurate.. as one of the shuttles on the avatar is actually in scale at least 1half times the the size of a 747 jet which would make the starship considerably bigger than a nimitz class carrier in scale
theblaquebaastid 2 months ago
@theblaquebaastid The aircraft carrier is 333 meters long and the Venture ISV is 1502 meters ... about 4-5 times longer.
Bantokfomoki 2 months ago
LMFAO.. not gonna lie when i first started watchin i thought here we go another idiot savant deconstructing a sci-fi movie for its inherent technical flaws... but after watchin i was pleasantly surprised &amused at both your seemingly accurate calculations &incredibly black (if unintentional) humour
however id like to ask why u didnt in your calcs include for time dilation (if it matters) &would also ask what difference ship mass would have if any in vacumless, frictionless space?
theblaquebaastid 2 months ago
@theblaquebaastid At .7c and 6 years, time dilation isn't a significant quantity. You need to get over 90% to make a real difference. The mass of the ship won't make any real difference. Antimatter is too energetic a fuel to use for extremely high speed in short time periods (like 6 months).
Bantokfomoki 2 months ago
Correct me if im wrong, If the power is correct, wouldnt that 10^17 watts be 10 kilograms of matter per second? And multipliying that by 15000000 seconds in 6 months that is 150000 tons of matter on board that will desapear(just for the acceleration) that is more that the total mass.
TARATATANTATAN 2 months ago
@TARATATANTATAN When I say "mass of the ship" I mean the hardware-payload part. Yes, the "gas" weighs more than the ship. For a ship attaining .7c via antimatter you need to about double the payload mass in fuel. (That's using Tsiolkovsky's rocket equation)
Bantokfomoki 2 months ago
Because you are not considering that the antimatter is traveling at the same velocity of the spaceship and thus it needs less energy from that advantage point to continue accelerating the spaceship that what you see from the ground. You have to analise the problem from the spaceship frame reference if you want to see them as the propelant sees them. You will find that much less energy is requiered from the advantage piont of the propelant.
TARATATANTATAN 2 months ago
@TARATATANTATAN You need to study up on Tsiokovsky's rocket equation. I haven't made any mistakes here.
Bantokfomoki 2 months ago
You are not taking into account that the propelant or antimatter or whatever is traveling WITH the spacehip. From your ground frame referece, E=1/2mv^2, and its derivative: E'=mva=F.v, if v=at, so the kinetic energy doesn't increase in a linear way, it depends on the velocity of the spaceship. ¿But how can that be if the force (F) of the engine is constant, and so the release of the antimatter energy?
TARATATANTATAN 2 months ago
closer than you could get bitch!!!
halogrunter 2 months ago
you say its "physicaly imposible" to have an engine giving that rate of energy with out melting, a rate of 200000 or what ever saturn rockets, but, why is that imposible? you can in principle imagine 200000 saturn rockets on the bottom of a spaceship all running at the same time... nothing metls there... you are just involved in a falacy of considering the total amount of energy instead of the density of energy. Say its uneconomical, not physically impossible
TARATATANTATAN 2 months ago
@TARATATANTATAN It's not physically possible. In my little addendum to this video, I took another look at the energy requirements and found that I'd need much more ooommph. Like 14 Tsar Bombas per second instead of one or two. That's 7 Tsar Bombas in that confined engine per second in each engine. That's so far impossible it's laughable. Unbelievably laughable.
Bantokfomoki 2 months ago
@TARATATANTATAN A Saturn rocket doesn't burn antimatter. There is not gamma ray problem. If you used 200,000 Saturn rockets ... the ship would work ... but only until you ran out of fuel and you'd be no where near even 1/100 c.
Bantokfomoki 2 months ago
you are too generous with that film, what about the garden of eden gaia type nature in pandora instead of battle for survival of darwin, and the statistical improbabilities of finding a humanoide animal having evolved on another planet independently and coinciding with them in space and time
TARATATANTATAN 2 months ago
Regardless, I agree that this is a very silly ship and the whole premise of the film is quite absurd. Photon sails accelerating a piece of paper, yet alone a 5000 ton ship at 1.5g is just stupid, especially after you consider the divergence of the laser beam at such distances. Plus, manufacturing the tons of antimatter you'd need to power one of these ships would have a huge opportunity cost, and would more than negate the payback from the unobtanium. May as well synthesize it.
SeersEnlightenment 2 months ago
@SeersEnlightenment You're a bit off in the tonage. The ship actually would weigh in at about 900,000 metric tons. You're off by a factor of 180 ;o)
But, yes, even for 5000 tons it's not workable. But it was a good movie. I liked it a lot. I like green foliage and exotic locations and panoramas. Beautiful. And what's her name and Jake-my-jake shoulda' locked their hair up before sex ... that woulda' been hot !
Bantokfomoki 2 months ago
then you can show with the Stefan–Boltzmann law that, with a double sided carbon radiator (which has an emissivity of .98, and can operate at 3500 K), you'd only need a radiator the size of a square 250 meters on one side. That's still like 4-5 times bigger than the ones shown in the film, but remember, radiators aren't needed at all in theory if the heat is carried in the exhaust, which is heavily implied. They're obviously there due to a design imperfection.
SeersEnlightenment 2 months ago
@SeersEnlightenment Unfortunately, the annihilation of antimatter gives off gamma rays that can't be controlled or directed. That's what would melt the engine instantaneously ... in the first millisecond of operation.
Bantokfomoki 2 months ago
@Bantokfomoki "can't be controlled or directed" isn't exactly proven. Though, I haven't even a clue as to what could be done about this, so I guess you win :P. Maybe the annihilation event occurs outside of the ship, with the engines only being there to propel the fuel away? The charged particles could still possibly push a magnetic field. Or maybe the gamma rays could be redshifted to something that could be reflected?
SeersEnlightenment 2 months ago
@SeersEnlightenment The annihilation is clearly within the engine compartment (from the deleted scene of Venture leaving Pandora). When a photon is the right wavelength an electron is raised up to a higher 'orbit'. Then it falls back and re-emits a photon (reflection). A Gamma ray is a photon but too energetic. It annihilates structures and creates a plasma. Your engine is turned to plasma instantly ... given the rate of antimatter posited.
Bantokfomoki 2 months ago
@Bantokfomoki Well, in theory all you need is around 1-2 kg of antimatter per kg of ship. That's not exactly useful in determining if antimatter would work in practice or not if a reasonable supply is readily available. The deleted scene doesn't show very much either - the ship is mostly obscured by the exhaust. Not conclusive enough to tell where the annihilation event actually occurs. Given the ships length, it could easily be a kilometer away from the engine.
SeersEnlightenment 2 months ago
@SeersEnlightenment The interaction must occur in the engine compartment because of the displayed nozzle effect, i.e. if it occurred outside of the engine it would spread out uselessly. And if it's IN the engine ... the engine is toast ... immediately because of gamma ray production.
Bantokfomoki 2 months ago
@Bantokfomoki Meh. The isv is silly and no one disputed that. But having the annihilation event occur hundreds of meters away from any part of the ship and having a sort of magnetic "sail" to obtain thrust from the charged particles might work. The intensity of the gamma rays would be greatly reduced as described by the inverse square law. This has its own glaringly obvious problems, but it's silly to jump to conclusions so early :p.
SeersEnlightenment 2 months ago
@SeersEnlightenment I don't agree with you at all. If someone says ... 2+2=4 ... can you dispute it and say, "It's silly to jump to conclusions so early"? With respect to the laws of physics as they are presently understood ... there is no possibility of going to another star in say ... 10 years travel time ... maybe in 2000 years travel time for a near star ... maybe ... but never in just 10 ;o)
Bantokfomoki 2 months ago
@Bantokfomoki Heh he heh...But 2 + 2 doesn't always equal 4. Check out fusion; the mass of matter left after a fusion event is less than the starting mass. 2+2=less than 4. When you say 2,000 years to reach the nearest star you are imposing an ultimate speed limit of 480 miles/sec on humanity. That's a ridiculously low speed even for fusion powered ships. It amounts to saying the fusion efficiency is going to be less than 1/10th of one percent. I know we can do better that.
1DanConnors 2 months ago
@1DanConnors What I mean by 2000 years is ... it's way beyond a human lifespan to get to Alpha Centauri ... by ANY MEANS WHATSOEVER (within the constraints of the conservation laws). I'd be real surprised if we could reach there in, say, 250 years (with good weather all the way).
Bantokfomoki 2 months ago
@Bantokfomoki 250 years means app. 1/60th c or 3,000 miles/sec. The ultimate performance of a fusion drive at 100% efficiency, with 2 stages each way, is .23 c, so a fusion rocket reaching .017 c would have an efficiency of only .54%, less than one percent. I believe your figures and prognostications are extremely pessimistic. I believe that humans will someday routinely travel at .1 c, and the zone of Human control in 6,000 years will be 1200 light years in diameter containing 8 million stars.
1DanConnors 2 months ago
@1DanConnors I think they will travel at .1c also ... but not by conventional means (fusion or antimatter). By "human control" do you mean we're going to conquer militarily all the other people out there? ;o)
Bantokfomoki 2 months ago
@Bantokfomoki I'd be surprised if we encounter any intelligent life within 600 light years of us. As you know from your other columns, I don't believe in flying saucers flown by aliens. But let's assume there are 20 alien cultures capable of IS travel in the galaxy. the nearest one would then be 11,180 light years away (by the law of averages). I recall from my grade school days being made to write on the board 50 times, "Men will never fly to the Moon." I mean the zone inhabitted by Humanity.
1DanConnors 2 months ago
@1DanConnors We certainly differ here. I'd guess that there'd be 20 alien cultures (indigenous) within 1000 light years ... probably more.
Men WILL never fly to the moon. Some people have attempted to fly there from the tops of tall buildings ... but they all went the other way.
Bantokfomoki 2 months ago
@Bantokfomoki Getting a bit knitpicky aren't we? I was arguing, of course, that men would go to the Moon. I have an interesting figure for you. The Saturn 5 rocket's first stage generated 950,000 times the energy of a Nimitz class aircraft carrier, but no one finds that impossible. If the SV engines had not been protected by regenerative cooling they would have melted and exploded in about 1 second. The figures you have tossed out in this clip prove nothing beyond the fact that the Avatar ship..
1DanConnors 2 months ago
@Bantokfomoki as rendered in the movie won't work. Indeed I don't think AM as a fuel will ever be used. Too dangerous. Fusion bombs are with us already, and if they are used with only 20% efficiency, and 2 stages, we can reach .1c. You have not demonstrated any violations of the laws of physics; you have only shown heavy engineering problems to be solved. What type engine can withstand a 13 Kton bomb blast per second? Answer: a pusher plate 800 feet in diameter.
1DanConnors 2 months ago
@1DanConnors They aren't "heavy engineering problems" ... they are "impossible" engineering problems. At some point, engineering problems become irrational to pursue because they afford no solution in the real world.
Bantokfomoki 2 months ago
@Bantokfomoki You kind of remind me of the physics professor during World War 2 who told his students there was no way a man made device could exceed the speed of sound. As he spoke, in the distance, could be heard the sound of antiaircraft guns at practice, firing their projectiles at 3 times the speed of sound. Other ultraconservative physicists argued travel to Luna was impossible because no fuel had a Vexh higher than escape velocity, and no rocket could exceed its own exhaust velocity.
1DanConnors 2 months ago
@1DanConnors Yes, and today we have people who are equally as ignorant of the laws of physics ;o)
Bantokfomoki 2 months ago
@Bantokfomoki A vehicle which reaches .1c, using propulsive energy in excess of the kinetic energy it attains doesn't violate any of the laws of physics. A fusion rocket operating at 20% efficiency doesn't violate any laws of physics. Pointing to an engine and saying there's no way in hell it or any conceivable engine can dissipate the energy of a 13 Kton bomb blast every second doesn't make it so. All of your "impossibilities" can be circumvented by enlarging the engines and reducing thrust.
1DanConnors 2 months ago
@1DanConnors
"All of your "impossibilities" can be circumvented by enlarging the engines and reducing thrust."
What is impossible is getting there in a human lifespan. THAT is not possible ... in principle.
It's a technological impossibility ... not a logical impossibility. Why don't you make a video, yourself, showing how and why it's possible to get to Alpha Centauri in 30 years or so (within the constraints of the presently known conservation laws)?
Bantokfomoki 2 months ago