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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 g

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?

kungito 6y ago
But what if it turns out that the experiment showed that cars really are faster in reverse? It turns out that by driving in reverse you create anti-drag in front of the car which pulls it forward. It's so simple yet powerful. How did you not think of this? Now everyone must think you are stupid because you were being so negative while everyone believed in it. Time to open the internet to see the reaction... Wow, no one cares. It turns out unless Apple releases this in their new car as iEM Drive with exclusive iEM Aqua car paint finish no one would know or care about this.
- heavenlyblue 6y ago
  It only happens in periodic dramas made for 15-year olds
Chris2048 6y ago
> 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.
- prof-dr-ir 6y ago
  > 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.
  - Chris2048 6y ago
    > I would point out that cars have gears How does that relate to airflow?
    - j4yav 6y ago
      It doesn’t have anything to do with airflow but does with whether or not cars are faster in reverse.
      - Chris2048 6y ago
        But it's a response to me pointing out air-flow is relevant (key).
        j4yav 6y ago
        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.
the-dude 6y ago
Have 'reverse car races' ever been a thing outside of NL? https://youtu.be/a59KyXhk74w?t=177 https://youtu.be/a59KyXhk74w?t=177
- pulse7 6y ago
  Indian Man Drives Car Backwards On Busy Highways: https://www.youtube.com/watch?v=aox_4-JNed8 https://www.youtube.com/watch?v=aox_4-JNed8 => so it may be faster indeed... :-)
- FrojoS 6y ago
  Awesome if you like crashes :-D Starts at 35:10 min
  - AnimalMuppet 6y ago
    Actually, in the US, sometimes demolition derby cars run in reverse, because they get to protect the radiators that way.
- vanderZwan 6y ago
  I don't know, but that video obviously needs a bit of Yakety Sax: https://tubedubber.com/?q=a59KyXhk74w:MK6TXMsvgQg:0:100:174:0:1 https://tubedubber.com/?q=a59KyXhk74w:MK6TXMsvgQg:0:100:174:...
- jacquesm 6y ago
  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 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.
foreigner 6y ago
What you do is short them on the stock market. Put your money where your mouth is!
- bjoernbu 6y ago
  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
- moonbug 6y ago
  ala, he'd rather put is mouth where our eyeballs are.
- sideshowb 6y ago
  An irrational market can stay irrational for longer than you can stay solvent
- Radim 6y ago
  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.
- 6y ago
josu 6y ago
This analogy would have also worked for a quantum computer proposal at the beginning of the 20th century.
- moomin 6y ago
  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.
Seb-C 6y ago
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.
- czzr 6y ago
  Doubtful. Who ever said that about rockets?
  - simonh 6y ago
    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.
    - qayxc 6y ago
      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.
      - simonh 6y ago
        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.
RyEgswuCsn 6y ago
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.
- plutonorm 6y ago
  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.
  - jacquesm 6y ago
    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.
    - marvin 6y ago
      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.
andlier 6y ago
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-range-efficiency/amp/ https://electrek.co/2020/03/24/tesla-model-3-roof-rack-box-r...
- electrograv 6y ago
  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.
  - bena 6y ago
    It was an aerodynamics engineer who suggested flipping the box around.
staticassertion 6y ago
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?
- prof-dr-ir 6y ago
  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.
  - dotancohen 6y ago
    > 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?
    - prof-dr-ir 6y ago
      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 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.
marvin 6y ago
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.
- saboot 6y ago
  ? 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.
  - kevinwang 6y ago
    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.html https://www.atomicarchive.com/history/manhattan-project/p1s2...
  - marvin 6y ago
    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.
- lostcolony 6y ago
  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 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.
Aeolun 6y ago
I have zero doubt that this whole thing could have been applied to the first airplane, or to a thousand other firsts.
dmos62 6y ago
That's an elaborate "I told you so"!
gcatalfamo 6y ago
There is a blockchain-applied-to-anything-other-than-finance metaphor hidden in this truly sublime analogy.
agumonkey 6y ago
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
HPsquared 6y ago
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.
nimbius 6y ago
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.
Certhas 6y ago
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 ...
deleted 6y ago
[deleted]

kungito 6y ago

But what if it turns out that the experiment showed that cars really are faster in reverse? It turns out that by driving in reverse you create anti-drag in front of the car which pulls it forward. It's so simple yet powerful. How did you not think of this? Now everyone must think you are stupid because you were being so negative while everyone believed in it. Time to open the internet to see the reaction... Wow, no one cares. It turns out unless Apple releases this in their new car as iEM Drive with exclusive iEM Aqua car paint finish no one would know or care about this.

heavenlyblue 6y ago
It only happens in periodic dramas made for 15-year olds

Chris2048 6y ago

> 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.

prof-dr-ir 6y ago
> 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.
- Chris2048 6y ago
  > I would point out that cars have gears How does that relate to airflow?
  - j4yav 6y ago
    It doesn’t have anything to do with airflow but does with whether or not cars are faster in reverse.
    - Chris2048 6y ago
      But it's a response to me pointing out air-flow is relevant (key).
      - j4yav 6y ago
        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.

the-dude 6y ago

Have 'reverse car races' ever been a thing outside of NL? https://youtu.be/a59KyXhk74w?t=177 https://youtu.be/a59KyXhk74w?t=177

pulse7 6y ago
Indian Man Drives Car Backwards On Busy Highways: https://www.youtube.com/watch?v=aox_4-JNed8 https://www.youtube.com/watch?v=aox_4-JNed8 => so it may be faster indeed... :-)
FrojoS 6y ago
Awesome if you like crashes :-D Starts at 35:10 min
- AnimalMuppet 6y ago
  Actually, in the US, sometimes demolition derby cars run in reverse, because they get to protect the radiators that way.
vanderZwan 6y ago
I don't know, but that video obviously needs a bit of Yakety Sax: https://tubedubber.com/?q=a59KyXhk74w:MK6TXMsvgQg:0:100:174:0:1 https://tubedubber.com/?q=a59KyXhk74w:MK6TXMsvgQg:0:100:174:...
jacquesm 6y ago
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 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.

foreigner 6y ago

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

bjoernbu 6y ago
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
moonbug 6y ago
ala, he'd rather put is mouth where our eyeballs are.
sideshowb 6y ago
An irrational market can stay irrational for longer than you can stay solvent
Radim 6y ago
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.
6y ago

josu 6y ago

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

moomin 6y ago
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.

Seb-C 6y ago

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.

czzr 6y ago
Doubtful. Who ever said that about rockets?
- simonh 6y ago
  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.
  - qayxc 6y ago
    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.
    - simonh 6y ago
      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.

RyEgswuCsn 6y ago

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.

plutonorm 6y ago
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.
- jacquesm 6y ago
  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.
  - marvin 6y ago
    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.

andlier 6y ago

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-range-efficiency/amp/ https://electrek.co/2020/03/24/tesla-model-3-roof-rack-box-r...

electrograv 6y ago
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.
- bena 6y ago
  It was an aerodynamics engineer who suggested flipping the box around.

staticassertion 6y ago

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?

prof-dr-ir 6y ago
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.
- dotancohen 6y ago
  > 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?
  - prof-dr-ir 6y ago
    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 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.

marvin 6y ago

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.

saboot 6y ago
? 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.
- kevinwang 6y ago
  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.html https://www.atomicarchive.com/history/manhattan-project/p1s2...
- marvin 6y ago
  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.
lostcolony 6y ago
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 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.

Aeolun 6y ago

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

dmos62 6y ago

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

gcatalfamo 6y ago

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

agumonkey 6y ago

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

HPsquared 6y ago

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.

nimbius 6y ago

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.

Certhas 6y ago

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 ...

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