I'd say that it's about on par with the faster-than-light neutrinos caper (tiny effect, violates known physics, probably result of experimental error, ...). Both would be very exciting if actually confirmed, but I personally found/find the chances too slim to (yet) get excited.
As to the whole "we don't actually understand how it works" - we still can't make up our minds as to how wings work, so this isn't overly novel. Sure, we can explain the outcome, but whether it's Navier-Stokes or Bernoulli or something else, we can't make up our minds.
I suspect this will be similar for a long while - although puts physics hat on I think this is likely a relativistic temporal quantisation effect.
> ... we still can't make up our
> minds as to how wings work, ...
Interestingly, I recently spoke to an aerodynamicist and mentioned this, and I was severely lectured. In the follow-up he mellowed a little, but I suspect the "we" in your statement refers to laypersons who don't have advanced training in aeronautics, and yet claim to understand about flow pressure, Bernoulli, etc.
I've been convinced that the people who genuinely work with these things and study them properly, actually do know how wings work. You may not, I may not, the mythical "man on the street" may not, but there are people who really, really do.
No, I've a masters degree in Physics, and did several research projects on turbulent/laminar flow. We have a detailed understanding of a variety of theories which correctly represent the lift effect experienced on a body moving through a flow, yet none of them do it perfectly or completely. We can implement the technology well, but not without the aid of wind-tunnels and brute-force computer simulations in order to validate our designs - had we a perfect mathematical understanding of lift - we would not need to.
Another example from Physics - quantum mechanics. We can describe the properties of a QM system, its outcomes based on inputs, the probabilities of states - yet we have not got the blindingest clue as to how it works. We have theories, but again, none are perfect - for instance see the Pilot Wave formulation of QM, which implies a deterministic universe, and isn't wrong, but isn't generally accepted - even though it describes QM systems well, for what little of it has been formulated in the last century.
Fluid flow is complicated, true - but the basic physical phenomenon of lift is very simple and completely understood: wings redirect air downwards, and the reaction force is what we call lift.
Agreed, but it's the fluid flow bit that complicates it. We absolutely understand lift in the Newtonian sense of a reaction, but wings, we're still learning about. If we weren't, we wouldn't have developed winglets and other such adaptations, as we slowly but surely assemble the theoretical particles into a coherent whole.
If we weren't, we wouldn't have developed winglets and other such adaptations...
Is the development of new programming languages evidence that we don't "understand" computers? In some very abstract sense, yes, but in a more practical sense - no.
Well, if brute-force computers simulations correctly represent a wing, then we do know how they work. We may need wind-tunnel tests even if we have a perfectly realistic model, because we may not know if our simulations converge.
In the case of the wing, all of the underlying physics is completely understood. It might be difficult to calculate and have complex behaviors.
By contrast, this "reactionless drive" posits both a completely unknown underlying physical mechanism and a major violation of physics-as-we-know-it (i.e. action without reaction).
It doesn't imply a deterministic universe any more than vanilla many-worlds. Sure, the pilot wave is deterministic. But when you actually measure the position of the particle? You get one of many possible results, with probability determined by the pilot wave. Big whoop.
We understand QM perfectly well in the only meaningful sense - we can predict the results of any experiment. There's plenty of arguing about "what it means" or "what's really happening", but that's not really physics in my book.
Exactly. I am constantly astounded by professional scientists who try to find a deeper meaning in mathematical models whose only purpose is to predict experimental results. Human brains work on intuition, but when dealing with imperfect models such as Quantum Mechanicns (QM), there is no intuition to be had. If Quantum Mechanics or General Relativity were perfect, we wouldn't actively be looking for a unifying theory to resolve their mutual inconsistencies.
Once we have a theory of everything, then we can begin trying to form an accurate intuition underlying the model. Until then, there is no point trying to intuit probabilistic models which are designed to predict experimental results, and nothing else.
With pilot wave when you measure (impossibly accurately...) you get the position - bit a statistically derived one. Pilot wave does imply a clockwork universe - albeit one so complex that it cannot be deterministically predicted, thus statistical QM works just fine.
Is argue that understanding the "basement" is very much physics - sure, it can err into the philosophical, but it's still definitely a "real" physical process which drives this.
You know, that's a really good point, I hadn't considered that maybe virtual particles might act like a gas.
Imagine if they permeate everything and are generally nonreactive, but still have pressure and viscosity (however small). Maybe the engine is working like an airfoil, displacing the gas locally and using entrainment to create a pressure imbalance with the surrounding virtual particles to cause a larger flow (like in the Bernoulli and Coanda effects). A broken analogy would be the lift to drag ratio of a wing. If it’s 10:1, then you can lift a 1000 pound glider by pushing on the tail with just 100 pounds of thrust.
Maybe a black body is on par with light pressure because the radiation is concentrated like in a rocket, but other geometries are able to interact more strongly with the quantum foam or whatever you want to call it, because they don’t radiate energy in one direction but instead excite the foam enough that it becomes opaque to radiation and can be interacted with (like what happens when an inert gas becomes a plasma). Say the thruster excited the foam so that it was moving faster on one side of the chamber than the other, then that would work like the top and bottom of a wing (where the air on the top side moves faster) and create a pressure differential. The chamber would move to the side with the highest velocity. This might sound far fetched but there’s some evidence that the wave particle duality can be simplified to particles traveling along waves:
Probably what we’re eventually going to find is that empty space is filled with these virtual particles, weighing much less than say electrons, and because of the uncertainty principle, they are spread over large volumes. So imagine the vertices being shed off of an airliner’s wing. Even though the wing is only a few feet wide, the vortices might be 100 feet wide, so maybe if you could put special glasses on, you’d see a big vortex being shed around the chamber, and if the foam weighs orders of magnitude less than air, the vortex could be really big. It’s probably even possible to tie the size of the vortex to the “lift to drag” ratio of the chamber. Now it doesn’t seem so far fetched that the engine could work when it’s pushing off such a large number of virtual particles.
"Once I asked him to explain to me, so that I can understand it, why spin-1/2 particles obey Fermi-Dirac statistics. Gauging his audience perfectly, he said, "I'll prepare a freshman lecture on it." But a few days later he came to me and said: "You know, I couldn't do it. I couldn't reduce it to the freshman level. That means we really don't understand it." David L. Goodstein, "Richard P. Feynman, Teacher," Physics Today, volume 42, number 2, February 1989, p. 70-75, at p. 75
I think Feynman is drawing a distinction between being able to calculate an accurate prediction, and "understanding" things intuitively enough to describe with plain English.
That particular version of a quote is listed on Wikiquotes as unsourced, and therefore unreliable. [1] However, he did say, "I couldn't do it. I couldn't reduce it to the freshman level. That means we don't really understand it." [2]
I have never heard the quote with the middle section you included "to a laymen in a few paragraphs"
I have frequently heard the quote without that section, that section seems flawed in that a layman would need to have all the underlying concepts explained to them also, indicating that application of the quote would not scale, as more underlying concepts were necessary to include.
I also generally subscribe to the idea that, if you can't adequately explain something to someone unfamiliar with the idea, then you don't properly understand it yourself. But my inability to explain something to someone says nothing about whether the phenomenon "is understood" in the more general sense.
None of the things mentioned so far that we "don't know how they work" are on a par with this. Flying with wings doesn't violate fundamental, and experimentally very well supported, symmetries like conservation of momentum, nor do high temperature superconductors.
My final sentence was getting at a mechanism by which momentum is conserved in this system.
If you assume that time is quantisable (big assumption, I know), and that the planck time is lorenz invariant (not as much of an assumption), then an EM wave at a fixed frequency moving from one reference frame to another could experience quantisation due to the shifting time-base, resulting in an apparent net deceleration - resulting in a measurable acceleration of the system as a whole.
And now I'll take off my fringe hat and get back to the day job.
Well, the relativity principle states that things don't "move from one frame of reference to the other". You choose a frame, and observe things on that frame; changing the frame of reference is your choice, and must not alter the results in any way.
Accepting a flaw in conservation of momentum is already hard enough without you (and the original paper) imposing a flaw on the relativity principle to explain it.
Ah, the old "it's Einstein so it must be right" gambit.
People used to say that about Newton - until experiment proved that he didn't have the full picture.
It's highly improbable that relativity is any different. Yes, it gives demonstrably correct answers, but that doesn't mean that it holds in all cases.
I mean, why would we be even talking about LQG if we thought relativity gave the full picture?
You're right that I was wrong to say it moved from one reference frame to another, which is clearly bollocks - the EM undergoes an acceleration to relativistic mass, then a deceleration.
You are proposing an experiment that shows that momentum does not always conserve. That's great, it's hard to accept the results (extraordinary evidence and everything), but if they hold, it's great.
Now, you do a huge amount of handwaving to try to explain the results, and in your handwaving you break another basic, unrelated principle. This time, no, I just won't accept your conclusions, you have no reason to break two principles when your experiments support only one.
By the way, the relativity priciple was first stated by Galileo, not Einstein.
> There are many explanations for the generation of lift found in encyclopedias, in basic physics textbooks, and on Web sites. Unfortunately, many of the explanations are misleading and incorrect. Theories on the generation of lift have become a source of great controversy and a topic for heated arguments.
There are lots of bits of science where we have "useful lies" used to explain things to people, but when you get more in depth things get trickier.
Clifford Stoll uses the question "Why is the sky blue?" as an example. You keep asking "Why?" as a response and see how far someone goes. Most people will say "light scatters"; some might say "Rayleigh scattering".
Of course, there is a difference between "Science knows but the general population hasn't learnt it" and "science doesn't know" but for a surprising amount of stuff science doesn't know, yet.
By "we", I mean humanity as a whole. Nobody would contest that there are a lot of widespread misconceptions about how an airplane - or, for that matter, anything - works.
One of the problems with this idea, that we have the physics "perfectly understood", is that even that statement isn't accurate. What we actually have are unbelievably precise models for how things work and people who understand those models at extremely deep levels.
But even something we experience literally every moment of every day, like gravity or magnets, we haven't the foggiest idea of how it actually works. We can describe in great depth anything we wish about our models for these things and experiments can reproduce our theories with exquisite precision.
But these models are merely complex rituals, we don't actually know, at a deep fundamental level, what happens.
The Feynman answer to magnetism, for example, is deeply unsatisfying because he describes all the rituals we've discovered with science about magnetism, but never really answers the question. His answer, in 7.5 minutes are "all the electronics spin in the same direction in iron and that produces a magnified magnetic field large enough we can feel". But why do spinning electrons produce a magnetic field at all? And why does that field work the way it does?
We have built beautiful mathematical tools to describe this force, down to elementary particles, but why it exists at all is a completely mystery.
By "understand" in physics, we really mean that we can predict what will happen in a given experiment to any desired accuracy based on the established "laws of physics".
"But even something we experience literally every moment of every day, like gravity or magnets, we haven't the foggiest idea of how it actually works."
I think this does a deep disservice to how much we actually do know about how the universe works.
My point is that people often confuse understanding the model with understanding the thing. The model becomes a ritual, it becomes a kind of complex dogma, and when people master the model they claim they understand it. But it's not true, they don't understand the thing, they only understand our description of it.
The next Monday, when the fathers were all back at work, we kids were playing in a field. One kid says to me, “See that bird? What kind of bird is that?” I said, “I haven’t the slightest idea what kind of a bird it is.” He says, “It’s a brown-throated thrush. Your father doesn’t teach you anything!” But it was the opposite. He had already taught me: “See that bird?” he says. “It’s a Spencer’s warbler.” (I knew he didn’t know the real name.) “Well, in Italian, it’s a Chutto Lapittida. In Portuguese, it’s a Bom da Peida. In Chinese, it’s a Chung-long-tah, and in Japanese, it’s a Katano Tekeda. You can know the name of that bird in all the languages of the world, but when you’re finished, you’ll know absolutely nothing whatever about the bird. You’ll only know about humans in different places, and what they call the bird. So let’s look at the bird and see what it’s doing—that’s what counts.” (I learned very early the difference between knowing the name of something and knowing something.)
Models are just a complicated way of calling something, not a way of understanding it. Getting experimental results just means you've used the correct name, not that you understand anything in particular about it.
Calling a hot bright thing "fire" doesn't mean you understand it at all -- no matter how many complex tribal dances you do around an open flame. Knowing what fire actually is gave us modern civilization. For many fundamental everyday things like gravity or magnetism, on the scale from "calling an open flame 'fire'" to "rocket ship", we're charitably somewhere around "learning to cook meat".
One of the problems with your argument is, as usual in these kinds of discussions, enthymematic: much lies in your particular notions of "explanation" and "understanding", which to you seem to self-evidently involve far from than their usual lexical sense --eg to many, Feynman's explanation of magnetism, with its remarkable succinctness, granularity and predictive power, is quite sound and satisfying!
So I would suggest you to begin by explicitly defining [1] what your particular notion of "understanding" is, so that you can then clarify what exactly is it that you find unsatisfying about modern physical law.
Okay, yeah sure. Good point. If you want to get down into those kinds of philosophical details, I'm not sure I'm prepared to do that. Right now, I'm kind of like the Supreme Court on pornography, I recognize understanding when I see it.
I think Feynman handles the question incorrectly. The question is about his understanding of magnetism, but he places the burden on the receiver of the explanation. If they don't understand the explanation then it doesn't matter. I do get his point in this and I'm not entirely saying it's wrong. But I think also that it's a deflection.
Lets assume a "presently omniscient" listener asking the question, somebody who may not have the knowledge before it is presented to them, but will understand the explanation perfectly as it's provided.
Suppose a Feynman or some other physicist has such a listener and they go on a deep dive into all the myriad and intricate details, the sum of all human knowledge on the matter -- this kind of listener would be able to follow along entirely with every last detail.
This listener would still not have an answer to the question "how do magnets work?" Because science doesn't actually know the answer to this. We have excellent descriptions of what magnets do, and what produces magnetism. We can predict to some nth decimal point of precision the outcome of just about any given experiment such that we don't really bother much with experimental physics about most of the day-to-day magnetism.
But why do those things produce magnetism at all?
The answers to this is basically "it just does". And that's as good as all our knowledge is. That's all we've arrived at. For all we know, every time an electron starts circling something, invisible universe fairies produce "magnetism" magic that does what we observe.
We don't know why magnetism does what it does, only that it does it.
But imagine if we actually understood it, at a fundamental level, if we "groked" magnetism and were the masters of it...
Interviewer: "What I want to know is what's going on ..."
Feynman: "Magnets repel each other."
Interviewer: "...between those two bits of metal."
Feynman: "Magnets repel each other."
Interviewer: "Well then, but what does that mean? Or why are they doing that? Or how are they doing it?"
Feynman: "Ah, [pause] uh you're asking ..."
Interviewer: "I must say that's a perfectly reasonable question to ask"
Feynman: "Of course! It's a perfectly reasonable question."
See also his quote about quantum mechanics - "There was a time when the newspapers said that only twelve men understood the theory of relativity. I do not believe there ever was such a time. There might have been a time when only one man did, because he was the only guy who caught on, before he wrote his paper. But after people read the paper a lot of people understood the theory of relativity in some way or other, certainly more than twelve. On the other hand, I think I can safely say that nobody understands quantum mechanics."
One can go further still and differentiate between "science has a reasonably accurate model" and "science has a standard way of describing and characterizing an effect."
"We still can't make up our minds as to how wings work, so this isn't overly novel. Sure, we can explain the outcome, but whether it's Navier-Stokes or Bernoulli or something else, we can't make up our minds."
Time to trot out my favorite quote about how airplanes fly, from Stick and Rudder by Wolfgang Langewiesche, page 9, published 1944:
»The main fact of all heavier-than-air flight is this: the wing keeps the airplane up by pushing the air down.
It shoves the air down with its bottom surface, and it pulls the air down with its top surface; the latter action is the more important. But the really important thing to understand is that the wing, in whatever fashion, makes the air go down. In exerting a downward force upon the air, the wing receives an upward counterforce--by the same principle, known as Newton's law of action and reaction, which makes a gun recoil as it shoves the bullet out forward; and which makes the nozzle of a fire hose press backward heavily against the fireman as it shoots out a stream of water forward. Air is heavy; sea-level air weights about 2 pounds per cubic yard; thus, as your wings give a downward push to a cubic yard after cubic yard of that heavy stuff, they get upward reactions that are equally hefty.
That's what keeps an airplane up. Newton's law says that, if the wing pushes the air down, the air must push the wing up. It also puts the same thing the other way 'round: if the wing is to hold the airplane up in the fluid, ever-yielding air, it can do so only by pushing the air down. All the fancy physics of Bernoulli's Theorem, all the highbrow math of the circulation theory, all the diagrams showing the airflow on a wing--all that is only an elaboration and more detailed description of just how Newton's law fulfills itself--for instance, the rather interesting but (for the pilot) really quite useless observation that the wing does most of its downwashing work by suction, with its top surface. ...
Thus, if you will forget some of this excessive erudition, a wing becomes much easier to understand; it is in the last analysis nothing but an air deflector. It is an inclined plane, cleverly curved, to be sure, and elaborately streamlined, but still essentially an inclined plane. That's, after all, why that whole fascinating contraption of ours is called an air-plane.«
I'm truly baffled at how people keep claiming that we don't understand how wings work when this obvious explanation is out there, one that any 8-year-old could give you, and it's absolutely right. "We don't understand how planes could fly upside down"---nonsense; it's the same way they flight right-side-up: by pushing the air down (or pulling, if you like).
The problem is that people see the various different explanations for how a wing works (pushing the air down, pressure differential, speed differential, circulation, what have you) and they think they're competing theories, not just different perspectives on the same phenomenon.
Edit: and of course it doesn't help at all that the silly and trivially disproven equal transit time theory continues to be the go-to explanation for how wings work for so many attempts to teach it.
Well, in my school (in France) the explanation was the 'equal transit time' which of course didn't satisfy me at all (it took me a long time to get a satisfying explanation).
So when schools teach this kind of BS, you can expect that the confusion will last a long time..
Okay but there's a difference in the nature of the "pushing down" of a rocket, a plane, and a hovering helicopter, and in how much of an impulse is actually inflicted on an external mass.
Yes. For an extreme example, imagine the wing of an airplane (or anything) sitting on the ground. It's putting a force on the ground, the ground's putting a force on it, and its altitude remains constant. The ground isn't getting any extra downward momentum, and the plane isn't getting any extra upward momentum.
Now consider a hovercraft. It sits on air. It does not push as much air downward as an airplane of equal weight would push. The amount of air it has to displace is probably proportional to the length of its perimeter (around the sides) multiplied by the height of the cushion of air it sits on multiplied by the air pressure underneath. Double the size of the hovercraft in both horizontal linear dimensions, and you've got double the perimeter, same air pressure (the machine's weight growing proportionally to area) and same cushion height, meaning you're holding four times the weight up with twice the air displacement.
Now consider a low-flying airplane. This is like an inefficient hovercraft, with the ground effect in play. Less air gets "pushed downward" than the same plane flying higher off the ground.
Consider a high-flying airplane. The ground effect is gone, but air's still got viscosity. Fly around the world forever and you'll notice that the amount of air beneath the plane is not actually increasing.
Hovering helicopters have to push more air downward than moving helicopters because they have to fight the stream of downward moving air that they've created for themselves.
If air had virtually no viscosity (suppose atoms were really tiny) then you'd have to fly by somehow forcing air to move downwards. If air had an extremely high amount of viscosity (relative to the mass and power of human-scale mechanical devices) then you wouldn't move it downwards at all -- planes would move around in the air like an amoeba or have a cylindrical conveyor belt surface. Our atmosphere is somewhere between these extremes.
The problem with these kind of unusual scientific results is often the experiment itself, not the results. It starts as "we do X, and it has a result of Z, and that makes no sense." Someone usually figures out that it's really "we do X (and Y), and it has a result of Z, and that is completely expected based on Y, and X is irrelevant as expected."
There's also that nice graph of measurements of the speed of light versus time, in which experiments tended to reproduce the results of (erroneous) previous measurements, due to confirmation bias.
And Cold Fusion... ugh... I was at Georgia Tech in 1989 when they announced to the world that they had reproduced some aspects of the cold fusion experiment. So embarrassing.
Reproducing an experiment, even with reputable scientists at NASA or reputable universities is in no way a guarantee.
These were other, earlier experiments, which the current experiment is attempting to duplicate. Importantly, while the new experiment has superficially "confirmed" the previous ones, it shows a much smaller effect.
When the magnitude of the observed effect scales roughly with the margin of error of the experiment, one has very good reason to be skeptical ...
The previous tests were on an EmDrive, while the current one was a Cannae drive, which is a related but different design. The EmDrive guy claims the lower thrust is to be expected due to the design difference.
<Cough> You shocked me so much that I read the article! :-)
(I follow the subject by browsing news now and then at http://talk-polywell.org/ which really is about the small fusion projects. That place should have more details then at Wired.)
Well yes, without those it wouldn't even be worth talking about. I don't think the several experiments so far rise to the level of "extraordinary", but now that this is capturing so much attention, I don't doubt we'll get there soon.
God DAMN this is exciting.