Hacker News Reader

Comment by prof-dr-ir | Hacker News Reader

There were days on the internet when a car analogy was appreciated -- let me try here.

Suppose there was a rally driver who would claim that rally cars could go much faster if they were always driven in reverse. He did some rudimentary experiments and might have found a significant improvement. The general public and other racing drivers, who in my analogy can all be wonderful people but happen to know little about the mechanics of cars, are naturally enthusiastic: a potential breakthrough in driving! But clearly we need more experiments. So other rally drivers get to work: they set up an elaborate system with ropes and pulleys so they can reverse the driver's position in the car and run a car as fast as they can, but in reverse, on a test track. What do they find? Sadly, their answer is somewhat inconclusive, probably negative, but perhaps the test track had many bends. So they would like to repeat the experiment on a track with a few more straight segments: they write grant proposals, build a track, and plan other test runs... and all the time their progress is eagerly followed by the general public.

Now suppose you are a car mechanic in all this. What are you to do? This cannot work! It flies completely in the face of the way cars are set up, not to speak of the disadvantages in air flow. So you can loudly dismiss the claim as preposterous early on, but then you will be called a pessimist and the public point out that at least the rally drivers are trying something new - what the bleep have you been doing all this time? So you just wait the whole thing out, see it come... and go.

I guess I should at least be happy that I did not buy any shares in EnDrive Inc?

View on HN

There is a difference here: cars are built by car mechanics; they know cars inside out --- cars are never designed to drive in reverse. Physicists, on the other hand, didn't invent physics, so they know their current understanding of physics could be wrong.

This idea that we are so sure of everything is pervasive. The kind of people who like science are often the kind of people who crave certainty. And so for them science becomes like a religion, it provides them with a sense of certainty. Consistency. So when they rally against stories like this what they are really doing is reaffirming their own faith in an orderly universe, reaffirming their own faith in their scientific religion. It serves an emotional need. Which is why, paradoxically, their arguments are not alterable through logic.

If you go read what the real experts in a field have to say about the state of knowledge, they are often incredibly humble. They state that there is so much that they do not know. That are so many things that could be wrong. That there are even bigger pictures just beyond their grasp.

Now these reactionless thruster concepts don't look to be doing too well. But I for one am not particularly convinced that mach 's principle is so stupid.

This sort of argument is routinely used to dismiss the laws of thermodynamics as merely 'theories' and to then move on to the most outrageous violations of known physical law.

We are pretty sure of what we are sure of and we are pretty sure of what we aren't sure of, impressions notwithstanding. Science is a method, not a set of facts, and it has a built in mechanism to allow greater insights to replace lesser ones. As long as we stick to science we'll one day find the limits of what is knowable.

I don't think you and GP are in disagreement. The scientific method to let greater insights replace lesser ones is precisely to try and fail at falsifying observations that violate known physical laws.

No physical law is holy for this purpose, although scientists will necessarily have heuristics for what presumed observations they consider good enough to examine closer. Evidently, the EmDrive observations made the threshold! And now we know for sure. Well, close enough, anyway.

> As long as we stick to science we'll one day find the limits of what is knowable.

I’m rather inclined to believe the opposite. That if we stick to science, we never will.

> it has a built in mechanism to allow greater insights to replace lesser ones. As long as we stick to science

Well you're not sticking to science when you assume any non-explained phenomenon is "impossible" and dismiss it outright.

Science has a long list of "impossibles" that have been proven to be possible. Though of course that list was mostly of phenomenon we couldn't ignore.

Saying "EMdrive is impossible given our current knowledge therefore it is not worth measuring" is tautological!

Electricity and magnetism were seen as separate phenomenon as well and it seems a lot of people would be opposed to even try to put a compass next to a wire!

The only thing I know is that the skeptics don't get the Nobel Prizes.

Good, they measured, and as expected, no thrust. Cool.

What makes this article so refreshing and so compelling is that they replicated the NASA results, and then explained and eliminated them. Another "We don't see anything and it's impossible anyway so you guys are idiots or charlatans" would not be helpful. This is.

Just because nothing is 100% knowable ultimately, doesn't mean all unknowns are equal.

Everyone who doesn't want to invest 10000 human lives and a small countries total resources trying to find out if maybe oxidization isn't really exothermic but just somehow always looks that way (is fire hot?), isn't guilty of being incurious or religious.

Come on now.

Part of the problem is that it's much easier to come up with a new perpetual motion machine or reactionless drive concept than to prove that it doesn't work. After seeing them all fail, at a certain point people are going to stop paying them any attention. Oh, this time it uses X force in Y configuration? Go away until you have data, we could be more profitably spending time on just about anything else.

It's only difficult because typically it involves a claimed effect right at the limits of what's measurable. A real effect wouldn't have to be barely perceptible, would it?

The person who discovered nitroglycerine didn't somehow find the amount they could make to be right on the edge of detection.

> Part of the problem is that it's much easier to come up with a new perpetual motion machine or reactionless drive concept than to prove that it doesn't work.

AKA, the bullshit asymmetry principle

https://en.wikipedia.org/wiki/Brandolini%27s_law

I think the arrogance stems from language.

Certainty doesn’t exist, in fact, the only certainty is the certainty that everything we know is wrong at some level of resolution.

Science is the philosophy of being less wrong about nature over time.

There is a strong argument to be made that there is no scientific method: https://en.wikipedia.org/wiki/Epistemological_anarchism

Can’t say I agree with the idea, but it’s certainly interesting to consider and at the least should help strengthen or discard a few assumptions!

I think he’s conflating the process with all the other human factors involved. Sure, Galileo maybe did some shady stuff to convince people of his arguments. But that in no way makes a telescope stop working the way it does.

If you want to go down a rabbit hole, Nonlinear dynamics is another way to understand science. Many systems operate from a different paradigm of causality; it happens in biology, also common in fields like weather prediction where a large dataset is analyzed for patterns and then hypotheses are driven off the data in the opposite direction.

This has caused some controversy in the scientific community because researchers have been caught using the methodology to "reverse engineer" hypotheses without disclosure, effectively gaming the system.

"A theory is the more impressive the greater the simplicity of its premises, the more different kinds of things it relates, and the more extended its area of applicability. Therefore the deep impression that classical thermodynamics made upon me. It is the only physical theory of universal content which I am convinced will never be overthrown, within the framework of applicability of its basic concepts."

(Albert Einstein)

"The law that entropy always increases holds, I think, the supreme position among the laws of Nature. If someone points out to you that your pet theory of the universe is in disagreement with Maxwell's equations — then so much the worse for Maxwell's equations. If it is found to be contradicted by observation — well, these experimentalists do bungle things sometimes. But if your theory is found to be against the second law of thermodynamics I can give you no hope; there is nothing for it but to collapse in deepest humiliation."

(Sir Arthur Eddington)

As plato would say the wall is choosing to hold us up. We may not understand why but it continues this way. At any point this could change. It wasn't until the theory of gravitation that we were able to define our obvervation as a general law.

"Newton's law of universal gravitation is usually stated as that every particle attracts every other particle in the universe with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers"

This is still a law. We haven't proved this to be true even though it looks to be true.

Laws can get superseeded.

The phlogiston theory is a superseded scientific theory that postulated the existence of a fire-like element called phlogiston (/flɒˈdʒɪstən, floʊ-, -ɒn/)[1][2] contained within combustible bodies and released during combustion

https://en.m.wikipedia.org/wiki/Phlogiston_theory

Another example is Luminiferous Aether

https://en.m.wikipedia.org/wiki/Luminiferous_aether

They are just theories in the end where most are probably correct somewhat.

Thank you for more eloquently expressing a sentiment that I have harboured for some time. After quoting the relevant Cave Johnson quote from PORTAL 2 so many times... it clicked and I came to the realisation that there is only one way to “do science” you “throw it at the wall and see if it sticks”.

At a fundamental level, you must throw your results at the wall of publication and see if they stick, the only way science sticks is when it can be replicated by others. It remain on the wall!

When people’s refutation of things like the em-drive is simply “this can’t work” my response is “prove it” not because I believe, but because “can’t work” just isn’t science, science is done by proving that something “does not work”. That means for something like the em-Drive you prove it doesn’t do what it claims, you prove it by replication and better measurement... and you learn how to build things better, learn how to measure better and that’s the value of these efforts! Or you prove it by detailed non destructive analysis of the experiment apparatus and prove your work by detailed physical simulation, publishing your code to prove you didn’t make any mistakes yourself! You cannot just give the answer you must show your work if you expect to go around calling what you do “science”. Providing such proof is not a waste, or bad science, it is the very essence of science itself.

You are missing a very important part of how science is done: science starts with a hypothesis, the refutation or confirmation of that hypothesis is done by experiment. Plenty of science has been locked into the theoretical phase for decades before experimental verification could be obtained.

If all we did was experiments we'd surely find some interesting stuff but without theory to guide where to do the next set of experiments science would be very inefficient. It's the closing of the loop that powers this tremendous progress you see from the renaissance to today.

Without that we'd be stuck in alchemy, astrology and other pseudo sciences.

Science must find a balance between extremes in how experimental resources are invested:

Extreme “Exploitation” Bias: “For maximally economical progress, experimental physics must strictly stay within the hard boundaries established by theoretical frameworks.”

Extreme “Exploration” Bias: “For maximally fundamental progress, experimental physics must question all theoretical assumptions and boundaries with extreme suspicion.”

It makes sense to diversify the kind of experimental investments we make along this risk/reward or exploration/exploitation spectrum. There are unique dangers if we weight too heavily on either extreme.

> science starts with a hypothesis

No, science starts with an observation which is not explained by the prevailing theory. Then you form a hypothesis, etc.

At least in principle. The reality of science is a lot messier.

I think there's one more step that goes a bit earlier in the process. Before an observation is made, there needs to be a choice on what experiments are done. Typically, those measurements will be done with one of two goals. The first is to measure a free parameter in the theory that isn't well-constrained by existing experiments. (e.g. "According to Maxwell's equations, the speed of light should be constant. Let's measure that constant value." [0]) The second is to find an unintuitive prediction from current models, then measure what happens in those circumstances. (e.g. "According to special relativity, passage of time should vary based on velocity. That's weird. Let's measure and see if it is the case." [1])

The purpose of these is to narrow down which experiments are being performed, trying to choose experiments that will try their hardest to break an existing theory.

[0] https://en.wikipedia.org/wiki/Speed_of_light#Time_of_flight_...

[1] https://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experim... (This article currently has an incorrect edit made yesterday. It seems to be based on a mistaken assumption that the rotating earth is a stationary reference frame. The opening paragraph should read "were consistent" rather than "were not consistent".)

So much for theoretical physics then. Or Einstein's 'gedanken experimenten'.

> The kind of people who like science are often the kind of people who crave certainty.

Just to clarify - are you implying scientists crave certainty, or non-scientists who enjoy reading about science crave certainty?

The life scientists I know are the people in my life who are the most comfortable with uncertainty, or at least can recognize how uncertain the world can be. Perhaps they crave quantifying the uncertainty? But they certainly understand, respect, and live with uncertainty.

I took it to mean the fans of science who pile into forums like HN with expressive enthusiastic skepticism, the kind of people who think experimental physics is like working on a car.

> Just to clarify - are you implying scientists crave certainty, or non-scientists who enjoy reading about science crave certainty?

Mostly the latter, but also the former to some degree. The scientists holding the status quo are often the most resistant to a paradigm shift.

Scientism. The deification of scientists and our current models.

Which is ironic as we know our models are wrong somehow as we can't mesh Quantum mechanics and general relativity. There is clearly some undiscovered idea or principal.

Science is about the process not about the body of knowledge we amassed. Science is about doing experiments to poke at the gaps of our knowledge. Not to like the Ancient Greeks debate our way to truth or worse declare something false based clearly on our flawed understanding.

Do you really believe this?

Celebrity scientists aren't deified... in fact, they have a tough life because people assume they're all knowing. Look at our man Neil DeGrasse who called a Bull a Cow because where he lives in NYC everything is a cow and he got ripped by other scientists for being stupid.

There is no universality to people period... i'm not sure why you feel its important to label some as "scientism" when there is no such thing as "scientism" with any universality.

Scientists aren't deified because people assume they're all knowing?

As for scientism, there's a lot of people in this thread who essentially said "We could have known it wouldn't work by basic application of conservation of momentum". Or some other principal held to the standard of absolute truth.

Our knowledge of the world is faulty and incomplete. All scientific knowledge is subject to tweaking or replacement based on experimental evidence. Not the other way around.

We have models and guesses of how the world works, we don't have its source code.

Actually the whole point why this EM drive is interesting actually is that the measurements contradicted conservation of momentum. Otherwise having a small effect not contradicting any established physics is basically worthless.

Sure, but if the contradiction bore out, then what's false (at least in some edge cases) is established physics not the experiment result.

The strength of the established physics just means that there is an extremely high chance that the EM drive is experimental error, especially with the small effect size, rather than something novel.

Feynman said something like true science is not believing anything you hear and something you have to experience. If you believe anything without doing the work then you’re cargo culting science which is deifying it.

The framing of "science becomes like a religion" is just projection, nothing else...

For many of us, we just accept that science is, what it is, and its the facts we know at this time. That doesn't mean unwavering absolute faith as implied by saying it's religious, it's just we don't feel the need to have knowledge be anything else other than knowledge that we continuously build upon.

Of course in general, lots of scientists know much more than other scientists and there is always bickering, people who have their identities married to it and so much more - but often times those very same people are often religious too so i question if the religiosity argument really exists or if its merely weaponized by people who fear the comfort of others who are ok with science without faith.

well everything is a people thing because we’re people. What science offers is proof and data that can be reproduced. So no two scientists bickering is not the same as two theologian.

but to those who believe in theology it would appear as such...

I appreciate the nuance here. As a person of faith one of the things I love most about both science and religion is the sheer amount of mystery there is in all of it. If there were no mystery in either, science would be dead and faith would be unnecessary. Yet science and religion pretend to be opposed.

Throughout history the greatest clashes between faith and science have occurred when scientific understanding threatens the faith-based assumptions of the age. Imagine Abraham arguing with God over his request to sacrifice Isaac. Instead, he reasoned that God would find another way.

Sometimes our understanding of religion limits our thinking with regard to not just science, but our faith as well.

I'm an atheist. I also have a degree in comp sci a degree in Mathematics and a master's degree in mathematics. I read arxiv daily. I love science, I read constantly. Watching the cutting edge of science from afar is a passion of mine. I like to try to hold a holistic vision of it all in my head - an impossible task, but it keeps me busy.

So, I'm not an enemy of science, I just dislike people harping on about 'impossible' from behind their keyboards when they have little more than a rudimentary knowledge of the subject at hand and too high an opinion of authority.

"God doesn't play dice." and then he kind of did. (Einstein on Quantum-physics)

Impossible is a absolute and science doesn't deal in absolutes. Just in likelihoods and observations.

> This idea that we are so sure of everything is pervasive

I think this is a common misconception made mostly by people who distrust science as a whole, but not really broadly held. I don't know anyone who understands an area of science at any depth who holds such a view.

The really broad problem is that in science there are things we have very high confidence in, and there are things we have very little confidence in but are the best working models currently - and everything in between. However, communication about where the confidence lies is often poorly done. Many observers who mostly hear about things through the lay press have no good tools to differentiate between "some person with a Ph.D said Y once" and "the vast majority of experts in this field are confident that X".

You are quite right that real experts have a healthy feel for what they don't know - and often humility - but those are often very different things from those that worry people outside the field. All of those same experts could happily give you a list of things they and their colleagues have very good confidence in. It's almost always the right thing to do to accept these and move on.

On the flip side any scientist will tell you there is small but real value at the margins for someone plugging away at a "crazy" theory. They are almost always wrong, but occasionally it turns up something really interesting. The trick is not to involve more people or too much resources, as these are long bets that will mostly fail.

> If you go read what the real experts in a field have to say...

If you go to read what the real experts in the field have to say then you would learn that not a single one of them thought that the EM Drive had even the slightest chance of being true.

In fact all the publications and work on EM Drive strictly avoided the real experts (physicists). They were all engineering journals. A paper that claims experimental evidence that overturns all physical theories from Newton onwards that's very telling isn't it?

I have always found that people that enjoy science are comfortable with uncertainty. I worked at Bell Labs for 16 years from the mid 1980s through 2000, and I found a lot of people still looking at things that "we all understand" and still wondering about how it really worked.

Science is never 'settled'. There is the current understanding of the art, but that current understanding is not always fulfilling. There are edges and holes in most domains in science where people are poking around wondering how it really works.

A lot of the things I implemented as an engineer (I am not a scientist, but I worked with scientists) were attempts to answer questions. Many of them having to do with "how do we measure this thing, without touching it?" Modeling information and making decisions based on observations against what you were expecting to observe.

> they know their current understanding of physics could be wrong.

Sure, we do know!

And we know how to recognise when someone masters current literature (a.k.a. factual knowledge) and proposes a breaktrough in a yet uncovered field, and when someone is speaking out of his ... nothing!

If you prefer a non-car analogy: we all do know that a hundred consecutive heads is possible, still you are not going to bet your week pay on it, even if you were promised 2^100 weeks of pay in return.

> we all do know that a hundred consecutive heads is possible, still you are not going to bet your week pay on it, even if you were promised 2^100 weeks of pay in return

The expected reward is just one-week's pay --- you have to offer better than that with all the uncertainty ;)

What if the reward is potentially infinite amount of money? If the investigation proved our current understanding of physics wrong, that could lead to historic breakthroughs in natural science.

Better yet, we don't know what the odd is. It might only need 32 consecutive heads.

I'd be very curious how it's possible to have 2^100 of anything :)

Oh, it's just 1024^10, a bit more than 10^30, or 10 million moles.

A water molecule contains 18 nucleons, thus a mole of water weighs 18 grams. 10 million moles of water are 180 cubic metres: an Olympic pools contains an order of magnitude more moles than that! ;-)

Sure, I hope nobody is paid so poorly that 2^100 times its week salary exists!

There are certainly people who aren't paid anything.

There are plenty of cases where someone who doesn't understand the underlying theory has contributed due to the outsider effect or just pure luck. The hype, and the swindling are not ok, but when an organization like NASA thinks they maybe successfully reproduced an experiment that invalidates a law of nature you have to keep trying. Sure I'm hoping for new science, always, because that is more fun, but mostly you need to know for sure what the experimental error was so that you don't repeat it in an experiment whose result you aren't as skeptical of.

> There are plenty of cases where someone who doesn't understand the underlying theory has contributed due to the outsider effect or just pure luck

Are you talking about anyone who was born in the last 100 years?

Lemaitre?

A low number of dollars spent to put to bed an idea that would have upended physics is a fairly cost effective play in the risk to reward game. That’s what it comes down too.

Negative results are good. Utter quackery is not good. But hard data from experiment is usually not quackery. Even if the whole thing stands outside the established paradigm. I’d argue we could stand a bit more of it, in this age of funding bandwagons and careerism.

> Utter quackery is not good.

That's the OP's point. The EmDrive is utter quackery. It cannot exist because it necessarily violates the laws of thermodynamics. Anything that disproves those will literally undermine the entire foundation of what we understand about the universe. It would be directly comparable to discovering that the earth is flat.

We already know the laws of thermodynamics has exceptions. In very small systems, the entropy of a system fluctuates randomly - up and down. A light ray traveling over extremely long distances will have its energy reduced through red shifting, and that energy doesn't "go" anywhere, it is destroyed. In both of these regimes, over extremely small scales and extremely large scales, there are exceptions carved out of the laws of thermodynamics.

We know for certain that our understanding of physics is incomplete. General relativity (as formulated) is certainly wrong, because it precludes the possibility of small things existing; and yet they do. Quantum mechanics (as formulated) is certainly wrong, because it precludes the possibility of curved spacetime, and yet we know spacetime is curved.

There is, of course, a minuscule possibility that the emdrive actually works. It almost certainly doesn't. Ballpark one in a thousand. But we can't exclude the possibility that it works, based on the principle that the the laws of thermodynamics, which already has two exceptions, cannot have a third exception.

There's big talk about humanity traveling to other stars, colonizing other star systems, colonizing the galaxy and so forth. For this to happen, we would have to be wrong about physics. There's simply not any way to do it by building on the foundation of what we understand about the universe. So investing in low probability speculative ideas like emdrive is still necessary, even though for any given idea, there are lots of nines that say it won't work.

>the laws of thermodynamics has exceptions

No, they don't. The "laws" you learn in high school are large scale approximations to the actual rules, which is codified in stat mech.

It's like claiming solids are not solid because atoms... Of course physicists know all this.

>General relativity (as formulated) is certainly wrong, because it precludes the possibility of small things existing

Having worked on GR stuff for a long time, this is news. GR most certainly allows any size thing to exist - it's a continuous theory.

>Quantum mechanics (as formulated) is certainly wrong, because it precludes the possibility of curved spacetime

No, it does not. QM in curved spacetime is so old and well understood it has a Wikipedia page [1] - from which you can start digging back into the literature.

You should really google such claims when making them to be sure you understand what you're claiming.

[1] https://en.wikipedia.org/wiki/Quantum_field_theory_in_curved...

What an exciting time we live in, where links between quantum mechanics, thermodynamics, and GR May finally be emerging in physics! What will the final ramifications be? Hopefully something new comes of it. If there are cases where conservation laws break down, or physical principles constrain one another in unforeseen ways, and they can be accessed at human scale, what an exciting thing! I’d guess you mostly feel this way too if I have not yet imposed any quackery on you, and suppose where we diverge is I do not see the harm in exploration as far out as the experimenter can dream to go. —Even if there is no theory for it. I know, the horror! Do I think it will work? Well heck no. But that does not mean I wish the attempt to be quashed like I’m the inquisition. On the contrary, I bid them good luck. And if they do have good luck, they better have some results that are easily duplicated. I hope they do overthrow the foundations of physics. Why not? The earth will still possess curvature, and all the extant physics will still be as approximately right, and beautiful, as it was yesterday.

The guy had an experiment, his explanation for the results were utter quackery. I don't think the people at NASA expected his explanation was the right one, but they didn't have one so they replicated. MIT had an explanation of the results that was not due to thermal effects, and wasn't the originator's explanation. It didn't upend thermodynamics. The problem wasn't people exploring a tricky experiment, it was people buying in to a specific explanation of the experiment prematurely.

Can you name some of those cases?

>There are plenty of cases where someone who doesn't understand the underlying theory has contributed due to the outsider effect or just pure luck.

There are far more such cases where the outsider was wrong, so many more of these, that using the extremely rare event to claim this may be one is simply terrible reasoning. It is far more likely that this is yet another crackpot pushing nonsense.

No outside has found a breakthrough that for decades (the length the EmDrive people have been making noise) was discarded. In fact, when an outsider finds something useful or novel, for a long time now the science community nearly immediately understands and embraces it.

This is the opposite of that.

I really don't think cars are designed by the same people who end up fixing them - ease of repair really doesn't seem to be a big factor in lots of designs.

Ease of repair is a factor, but there are other factors. Safety and Fuel Economy (Aerodynamics and mass) are more important than ease of repair so many things to make it easy to repair just get tossed out.

Ease of repair has largely been replaced by lack of need of repair. Cars, especially IC engines, are so much more reliable today that repair is relatively rare. Engine rebuilds are almost unheard of on small cars. Transmissions regularly outlast the chasis. Even tires rarely get flats. People now expect to drive many tens or even a hundred thousand miles without engine failure, on no more maintenance than an occasional oil change.

This whole thing has been obviously dumb for a number of reasons not even related to physics. You could almost use it as a good litmus test for who should be running a company, or working at important positions in government.

> cars are never designed to drive in reverse.

that's just plain wrong, friend.

The design of a car is obviously limited by fundamental aspects of physics which are outside of the control of car manufacturers. For example, car manufacturers didn't invent combustion, aerodynamics, etc.

It's tough to know absolutely everything about a complex dynamic system, even if it's built by humans. Take the economy, for instance. Invented by humans, made up of humans and human technologies and concepts, and yet people only have vague ideas about how to control it.

Or take computers for that matter. People designed and built them from scratch. Someone had to design and lay out the transistors on the CPU, and presumably they know everything about how to do that. And yet we are currently trying to figure whether there's an ordering to switching the transistors on and off that would imbue the CPU with human-level intelligence. There are plenty of people who know computers inside and out, yet there are still questions that need answers. We have a whole discipline called Computer Science that performs experiments on computers for the purpose of answering these questions.

I agree that on this point the analogy is weak. But it describes the ignorance of all those hyping it up well.

People are generally aware that if someone is presenting a perpetuum mobile they are wrong. Free energy doesn't exist. The fact that you can't have free momentum is just as strong (and has been known longer), yet less widely intuited.

Let me give you an analogy though:

Let's say someone proposes a water base perpetuum mobile like this:

https://en.wikipedia.org/wiki/Perpetual_motion#/media/File:W...

It only works if you place the machine under a massive waterfall though. Now this would be very difficult to refute experimentally, because you have to account for all possible interactions in the waterfall.

That's what the EM Drive is. A perpetuual motion machine built in such a way that there's a lot of energy going around and it's hard to eliminate all spurious interactions.

> Physicists, on the other hand, didn't invent physics, so they know their current understanding of physics could be wrong.

They also know they have experimented extensively over the region this effect claims to exist, and have found nothing of the kind for well over a century, and that if the EmDrive did what some claimed, it would violate literally thousands to millions of experiments already conducted.

Claiming physicists don't know everything about possible physics does not imply they don't know a tremendous amount about the places they have extensive experimental and theoretical agreement. Those places are not likely to ever change.

Physicists don’t even build things anymore. They just plug in math. No wonder they’re divorced from reality.

> Physicists, on the other hand, didn't invent physics, so they know their current understanding of physics could be wrong.

Technically, yes. but not in the sense that the word "wrong" is generally used. Existing measurements confirm that the current theories are mostly correct to high degree of accuracy, and over a lot of measurements, in a wide range of circumstances.

Current understanding may be proven _incomplete_, but it won't be superseded by something completely different that contradicts those measurements. That would be a non-starter, but it's what people think of when they hear "x is wrong".

e.g. Newtonian mechanics is "wrong" or "incomplete", but it gives very good answers for everyday circumstances. Just not for very small or very fast.

The best essay on this subject is "The Relativity of Wrong", Asimov, 1989

https://chem.tufts.edu/answersinscience/relativityofwrong.ht...

On the other hand, this is the sort of attitude that would make an informed skeptic reject the theoretical possibility for nuclear power, two weeks before the first nuclear bombs were used in war.

It took a team of physicists four years to disprove this result. Did they do it just to prove a point, or because they didn't understand the car analogy? No, professional scientists are rarely that callous with their time.

There was a slim possibility that our understanding of physics was wrong, and now we know for sure that this was not an instance of that.

But everything that's really interesting happens at the edges. No groundbreaking scientific result, ever, has happened by rejecting out of hand unlikely observations that violate established theory.

? A nuclear power plant was built before the bombs. It's main purpose was to generate bomb material, but they definitely showed the principle worked and powered a lightbulb with it.

Not 2 weeks before, but the parent comment applies if you switch out "two weeks" with "a couple years", right?

https://www.atomicarchive.com/history/manhattan-project/p1s2...

I was making a rhetorical point, but it works if you switch out 'theoretically' with 'actually', and 'two weeks before' with 'while the first nuclear reactor was supercritical in Chicago'.

I'm pretty certain that the practicality of a nuclear chain reaction wasn't widely accepted in December of 1942, even though fission was first demonstrated by Meitner and Hahn three years before.

These weren't rejected out of hand - from the very first results there were ripe questions being asked (i.e., why did it take so long to measure thrust, and how were they controlling for thermal expansion, see even here on HN, quoted elsewhere in this thread - https://news.ycombinator.com/item?id=12962579 )

You're absolutely correct that building better testing to disprove it completely is a good thing to do, just to remove the extreme unlikelihood that one of the most fundamental laws in thermodynamics are incorrect, but extreme skepticism is definitely warranted when the claim is so huge, and people are able to find realistic flaws (sufficiently realistic as to be proven to be correct) that would explain it entirely.

I'm not arguing against the points you are making, but they are subtly different from what OP implied. It's hard to make specific claims against a vague analogy that just seems to embody a mindset, but that's what I'm trying to do. And it's not a strawman even if it would happen to miss OP's intent; you see this mindset everywhere.

My point was that OP appears to would have rejected this hypothesis out of hand, and that this approach that would be wrong if everyone that matters did it. Obviously there were people who mattered who did not, as the experiment demonstrates.

A posteriori it's difficult to put numbers on it, but I'd say this experiment was worth doing even if your heuristics put it at a 0.1% chance of succeeding. Obviously that's not the case for Mad Morty's 1000th garage-built perpetual motion machine, but multiple physicists obviously evaluated this hypothesis as less shitty than that.

All in all we would probably agree if we could just zero in on our key points, so I probably shouldn't have spent four paragraphs on this.

I was under the impression that atomic weapons and reactors were both based on known physics, not the overturning of it.

If it wasn't considered theoretically possible, what do you make of Einstein's famous letter?

The bomb really wasn't known. Some people speculated that it may work, some people were sure that it couldn't.

I've finished https://www.goodreads.com/book/show/170428.Now_It_Can_Be_Tol... last week, and from what I understand, a lot of people didn't think that bomb is a possibility (for example, the Germans weren't really sure), and even when the Manhattan project was running several years, the scientists still weren't sure that the bomb will work as expected. There was a lot of variables in play, and for example, materials for the bombs weren't available for testing in large enough qualities.

One of the concerns, from what I understand as a layman, was that a critical amount of material will blow itself up too early, so that most of the material won't be part of the explosion. This was solved, I think, by some kind of neutron reflectors, or something*.

There are few chapters about how part of the Manhattan project was capturing scientists from France, Italy and Germany. When they captured them, their housing was bugged and there are transcripts from that time in the book. When the bombs were dropped, they generally couldn't believe that it really worked.

* One of the transcripts shows, that the Germans didn't think of this, and when they thought about the bomb, the thought about basically overloaded nuclear reactor, which would be big, heavy and impractical for use as a bomb.

All the time on HN I read posts saying how we should celebrate negative results. Here we have a negative result.

Why not celebrate it?

Claim: banging your head against the wall makes you smarter.

Experimenters: that sounds amazing! So we tried. We can report that all test subjects reported a massive headache. Unfortunately none seemed to get significantly smarter.

You: a negative result, well done! Time to celebrate!

And now I hope you will accept my apologies for exaggerating to the point of being rude, all in reply to your entirely reasonable question.

I guess my point is this. There has to be a cutoff where a claim is too obviously incorrect and testing is simply not useful any more. But the natural cutoff point depends enormously on perspective. Are you a car mechanic, a rally driver, or a complete layman? And as the latter, who do you trust?

My original comment was written to highlight the frustrating perspective of the car mechanic. But an interested layperson (or a non-expert handing out grant money) might have the more difficult time.

  > I guess my point is this. There has to be a cutoff
  > where a claim is too obviously incorrect and testing
  > is simply not useful any more.

Such as claims of giant lizards ruling the Earth, or claims that all matter (and time!) was once a singularity, or claims that man had descended from - get this - apes?

Emphatically not. There is an important difference between 'outlandish' and 'in flagrant contradiction with billions of experimental results [0]'.

I am not saying that the difference is always easy to spot, but I think that you cannot deny that it exists.

[0] For a crude estimate, see 'number of collisions per second' at https://home.cern/resources/faqs/facts-and-figures-about-lhc . And those people are looking really hard for possible violations of the law of conservation of momentum: in this context it is called 'missing transverse energy' and it is a key method in the search for new physics.

But it seems to me that in the earlier EmDrive experiments, there were forces found that were not explained satisfactorily. Now, through better experimental controls, all of these have been accounted for. That sounds like valuable research to me.

Good point. It should both make future experiments more accurate and also debunk similar claims more easily.

Science isn't a bunch of scientists saying "we doubt it'll work"—science is a bunch of scientists experimentally proving it doesn't work.

The people funding the scientists decide what's worth testing. In this case, the possible benefit vastly outweighed the cost of testing.

To fix the head-to-wall metaphor: in some experiments, subjects who banged their heads against the wall reported being cured of all mental illness. However more rigorous tests showed this remarkable effect was actually a placebo caused by the subjects believing they were involved in making history.

hello, speaking as a diesel engine mechanic, this is exactly what modern emissions controls have sadly become.

professional drivers (truckers) want to cut out all the emissions control systems because "older trucks get better mileage!" On the face of the issue this seeems to be true, but even after cutting everything out and switching back to low-grade diesel all you've done is create a smoke and soot belching mess from the 1960's. Why is this?

Two reasons: older trucks got great mileage because there was less traffic congestion and fewer weigh station stops, and the national maximum speed limit law in 1973 made sure trucks drove a speed that got great mileage.

Interesting analogy, but the pessimistic view does not bring any progress. The optimistic view may often be wrong, but when it is actually right, it makes our civilization progress.

Not so long ago, the experts knew and said it was impossible to land and reuse a rocket.

Doubtful. Who ever said that about rockets?

There was huge skepticism in the industry that landing and re-using first stage boosters was viable. Tony Bruno of ULA in 1015, 7 months before SpaceX recoverd their first booster, on their plan to recover the engine module of Vulcan:

"Our concept for reusability is inside that mathematics and realizes that maybe reusability does not start with entire stages,"

It's not that they thought it was impossible to do at all, but they thought the weight requirement of fuel, landing legs, heat protection, etc would be so high that it would eat up too much of your payload capacity.

Scepticism is way too often confused with negativity, pessimism or even outright hostility.

It's also often overlooked that a solution might not be the best fit for everyone. Just like it's best for the Falcon 9 to discard the second stage.

Right, the reason ULA can't adapt Vulcan to land the first stage propulsively is it can't throttle down low enough. It's only barely possible with the F9, and that's because it uses a cluster of smaller engines and happens to have one in the middle.

That wasn't a design choice driven by reusability, originally SpaceX were aiming to recover the stage using parachutes. The original plan was a falcon with a cluster of 5 engines in a ring. Using a cluster of smaller engines was for two reasons. First because they didn't have the resources to develop a new larger engine. Second they wanted to mass produce the engines to get production efficiencies and a bigger run of smaller engines worked better for that.

It just worked out serendipitously that this lead to a design that was very well suited to adapting for propulsive landings. If they'd developed F5 first instead, they wouldn't have been able to land it because without a single centre engine they would need to use at least 2 engines to land, and the thrust would be way too high. Even with a design with a centre engine, the Merlin would be too powerful for the weight of an F5.

This isn't a criticism, it's just the way things worked out.

No. The optimistic view incurs opportunity cost: instead of attempting the impossible, something useful could have been done instead.

I see one little caveat with this argument, though: is it always known in advance that something really is impossible?

As long as there's enough resources to go around to pay 8 figure meme-value dollar amounts for digital assets without intrinsic value, I think there's no harm in spending a fraction of that on possibly fruitless research.

> 8 figure meme-value dollar amounts for digital assets without intrinsic value

The problem is the people who do that are hell bent against letting the government tax them to fund such research, so our research resources are immensely more constrained than they could be.

What you call the "pessimistic view" might be very enthusiastic about projects that are orders of magnitude more likely to work. So in my opinion, the relevant axis is not optimistic vs. pessimistic, but informed vs. uninformed.

Can an outsider with no knowledge of the field make a chance discovery? It's theoretically possible, and we might want to support undirected experimentation for the one in a billion chance that something might work. But we should take those probabilities into account when allocating our collective resources.

So tell me, how do we calculate probability for yet unknown phenomen? Which is more 'probable' to be correct - string theory or loop quantum gravity?

If I want to investigate einstein rosen bridges, whats the probability I am wasting my time?

Usually you look at the volume of experimental evidence that directly contradicts it. In this case there’s quite a lot.

This this this. Sooooo much. This always was flying spaghetti monster level unlikely. People simply do not understand how tightly constrained things like this are by existing evidence. And almost uniquely so.

When experimentalists announced they had discovered super-luminal neutrinos, everybody reacted exactly like all the amateurs here are saying we should: Explore potential theoretical ramifications while being aware that it's most likely measurement error and encourage further study until we're sure.

Not so for the EMDrive. Why? Because the idea that using nothing but electromagnetism you can violate this foundational property of every physical theory since Newton (_including_ electromagnetism) means that somehow your electromagnetic device, while operating well within the range of millions of other experiments out there, somehow triggered behaviour fundamentally different from electromagnetism. Different from the type of theory that electromagnetism is. Different from the type of theory that every physical theory ever found to describe reality is. And yet this phenomenon that is utterly _different_ than anything else we have ever seen went completely unnoticed in the millions of em sensitive experiments performed by everyone from undergrads to international labs over the last two centuries.

In the strictest sense it's not logically impossible that this could happen. But only in the sense that it's not logically impossible that the flying spaghetti monster is manipulating every scientific experiment performed to hide itself.

We had rockets that landed with Apollo. We had rockets that were reused with the shuttle.

Who said it was impossible to combine them? And "impractically expensive and counterproductive" doesn't count.

> We had rockets that landed with Apollo

Correction: We had rockets that could land on the moon. There was no orbital-class rocket that could launch from Earth and land back at launch site (or further downrange). The difference in gravity + lack of atmosphere is a big factor.

It is like saying that the Apollo ascent module could get to orbit and therefore we can clearly make practical SSTO vehicles.

> We had rockets that were reused with the shuttle.

If you consider throwing away the massive external tank and external SRBs (without which it couldn't fly) and completely re-building the three engines after every flight.

> It is like saying that the Apollo ascent module could get to orbit and therefore we can clearly make practical SSTO vehicles.

If we didn't have to worry about fuel, we could. "put in enough fuel so it can land" is not a hard problem to solve with earth rockets, it just costs payload.

> completely re-building the three engines after every flight

It's complicated but the level of rebuilding was driven more by very high standards than it actually being necessary to make it launchable.

> "put in enough fuel so it can land" is not a hard problem to solve with earth rockets, it just costs payload.

I am pretty sure that the convex optimization algorithms used by SpaceX's landing systems are a very recent invention (http://larsblackmore.com/publications.htm). As for worrying about fuel, what's the point of a rocket if it cannot take any payload?

This reminded me of the extended range with reversed ski box for tesla. https://electrek.co/2020/03/24/tesla-model-3-roof-rack-box-r...

Ironically, this serves as an excellent refutation of the above analogy’s goal (to scoff at EMDrive experiments):

* Imagine telling a mechanic that mounting a ski box on your car with the fat/blunt end pointed forward seems to improve fuel economy vs being mounted the other way.

* The mechanic believes it’s absurd to claim you can improve fuel economy from a change that increases wind drag, so therefore your experiment is wrong since it seems to contradict established theory — case closed.

* Imagine that you more carefully measure, and find that it still seems to work surprisingly well (though also mysteriously reducing braking and cornering performance)!

* The mechanic still denies the result (which is unfair), and questions your test methodology and demands replications of the experiment (which is fair).

* Imagine someone else tries to replicate the experiment with a differently shaped ski box (i.e. not an airfoil, or with the airfoil shape vertically inverted), and fails to reproduce your results.

* The mechanic community concludes that the original result was obviously just experimental error, since the latter failure to replicate aligns with current theoretical consensus of what should happen.

In a similar way, early pioneers experimenting with winged aircraft design were laughed/scoffed at endlessly by established scientists/engineers of the era, ridiculed and crackpots wasting valuable time and resources.

The aerodynamics of the airfoil (which also explains the above ski box phenomenon) is an extremely non-obvious emergent effect, and even to this day is not as fully understood as most people probably assume.

It was an aerodynamics engineer who suggested flipping the box around.

Have 'reverse car races' ever been a thing outside of NL?

https://youtu.be/a59KyXhk74w?t=177

Indian Man Drives Car Backwards On Busy Highways: https://www.youtube.com/watch?v=aox_4-JNed8

=> so it may be faster indeed... :-)

Awesome if you like crashes :-D Starts at 35:10 min

Actually, in the US, sometimes demolition derby cars run in reverse, because they get to protect the radiators that way.

I don't know, but that video obviously needs a bit of Yakety Sax:

https://tubedubber.com/?q=a59KyXhk74w:MK6TXMsvgQg:0:100:174:...

For a bit of context: a brand called DAF ("van Doornes Automobiel Fabriek") came up with a very clever drive system, called variomatic. It is still in use today under CVVT in Honda vehicles. DAF had an unfair reputation as a 'womans car' because you didn't have to shift gears at all, nor was there a finicky automatic gearbox to maintain, just two pulleys and a belt for each rear wheel. Which gave it insane acceleration as well because the torque convertor gave maximum torque at the lowest speeds ramping down the torque gradually and continuously as speed increased.

One peculiar aspect of this drive system is that it allows your car to go as fast in reverse as it does forward! Of course the Dutch could not let this go without setting up a race around that theme, which was wildly popular in the past.

Since dafjes have an 'unfair advantage' you also got a secondary class, with other car brands, this is a video of that race.

Here are the DAFs:

https://www.youtube.com/watch?v=zoh8i0jfpTo

That video really hurts to look at by the way, the casual destruction of such a large number of what would be very special classics today is grating, especially that pretty 55 coupe is one that I'd love to keep around.

Creative destruction :-)

Fair enough, it is a bit creative, but only really the first time. They go for twice the original new price now!

If it makes you feel any better : I have very fond memories of these shows ( I was very small still ).

My mom had the real thing :)

She'd outpull Porsches just for fun...

In reverse?

Also, thank you for finally making sense of a childhood memory of a Jacobse & Van Es photo where they sit in a car, with the caption "200 km/u? Dat rijden wij al in z'n achteruit!"

This seems a lost battle. Every EM Drive discussion I have seen has been dominated by non-scientists pontificating about how we don't know anything, and our theories might be wrong, and we should keep an open mind ...

Re the airflow point, many cars are indeed MORE aerodynamic than normal in reverse, particularly hatchbacks.

It's best to have a smooth, progressive tail to minimise flow separation at the rear of the car (think of an airfoil shape - quite blunt at the front, thin at the back).

Hatchbacks often have very flat rear ends compared to the front which usually has a more progressive slope. A famous example is the Austin Allegro, but it's actually quite common.

I have zero doubt that this whole thing could have been applied to the first airplane, or to a thousand other firsts.

That's an elaborate "I told you so"!

There is a blockchain-applied-to-anything-other-than-finance metaphor hidden in this truly sublime analogy.

reminds me of the hyperloop bubble a bit

also for all the knowledgeable people hurt by naive enthusiasm.. I guess a healthy dose of cynicism is to find a way to benefit from this and then reuse them for your better thought out projects

What you do is short them on the stock market. Put your money where your mouth is!

How exactly could this be done reliably? With shorts you have to commit to a timeframe for not only finding evidence to reject the claim but also for the news to break and convince other investors.

Meanwhile you can be targetted by financial actors that play your positions on the stock market, at times even disregarding the atual company behind it. Further you have to mind monetary policy. If faith in the stock suffers compared to other stock but the overall market just goes up and up, your shorts have a problem again.

Personally, I have no informed opinion on EmDrive, but I have been very pesimistic about companies in the past and I am about some right now. Still, I do not think that shorts are anything appropirate for me. I'd much rather buy competitior's stock than burn myself with shorts or waste hundreds of hours getting into the financial market that I could also use to create value in my actual job/profession

ala, he'd rather put is mouth where our eyeballs are.

An irrational market can stay irrational for longer than you can stay solvent

How would that work, in the analogy?

Short the individual researchers? Research projects? Short private funding?

Scams like EmDrive (but there are countless others – "save the planet with X") may be amusing, as long as it's on someone else's dime. Live and let live.

But the minute they manage to convince enough people, whether by virtue or shady marketing, it becomes a political problem. And then it's your problem too, through taxation and "too big to fail", no matter your position. Shorting on the stock market gets you only so far, and only for entities that actually exist on the stock market.

The stock market currently thinks Gamestop is the most revolutionary company in the world.

This analogy would have also worked for a quantum computer proposal at the beginning of the 20th century.

Not really, the objection would have been it was completely impractical, and it was (and borderline still is).

When the facts change, opinions can change.

The objection to the EmDrive is that is that it makes no sense, which is much less likely to change.

> Now suppose you are a car mechanic in all this .. the disadvantages in air flow

Not sure a mechanic is better than anyone with understanding of car dynamics, but the "air flow" argument is the key to this.

Who are the experts on emDrive tech, and what principle does the emDrive violate? If you can't say, then you are indeed a pessimist.

> the "air flow" argument is the key to this.

I would point out that cars have gears, but then someone would say that in the US they do not, and I would have to explain that that is not the case, actually, and it would all get very tiring very quickly.

> Who are the experts on emDrive tech, and what principle does the emDrive violate?

A physicist would point out that momentum is conserved, so nothing can start moving without something else moving in the opposite direction, but then someone would point out that cars seem to be able to do just that, and then I would point out this big round thing underneath a car, and it would all get very tiring very quickly.

> I would point out that cars have gears

How does that relate to airflow?

It doesn’t have anything to do with airflow but does with whether or not cars are faster in reverse.

But it's a response to me pointing out air-flow is relevant (key).

He is saying that air flow is not more important than gearing, but if he were to raise it he’d end up in a never ending series of replies debating the details but missing the point.

Sure, but I don't agree gearing is in the same category of the specific thing I mentioned. Would he also end up in a never-ending series of replies wrt airflow too? If not, it has nothing to do with my point, if so why change the topic..

Apologies but I don’t really want to enter the endless debate either.

Literally in the first paragraph on Wikipedia:

It is purported to generate thrust by reflecting microwaves internally in the device, in violation of the law of conservation of momentum and other laws of physics.

https://en.wikipedia.org/wiki/EmDrive

Extraordinary evidence is required for extraordinary claims. Any hint of evidence at all is required for idiot claims before waisting people's time.

Reply on news.ycombinator.com