The EM Drive: Fact or Fantasy? 

OMG, reading the actual papers, getting competent people to analyze them, taking the latest hype with a grain of salt, and involving the viewers in clever ways... That's science journalism done *right*! Honestly, I've been a science enthusiast my whole life (and a scientist now), and I've *never* seen journalists report on it so seriously and professionally! (yup, not even Tony Darnell!). Keep up the great work!

"The first rule of Spacetime Journal Club is... we talk over our thoughts and remain open to all possible ideas and contributions from others before forming any solid conclusions." Hmmmm, that wasn't nearly quite as dramatic as the first rule of Fight Club.

If anyone is still watching this video, the effect observed from the EM drive was shown to be an effect of turning on the electrical system, because it interacted with earth's magnetism, or something like that. So the drive does not work...

The "Stop broadcasting, you're in danger" ending actually gave me shivers and a brief shock of fear, so good

I LOVE the way you approached this topic. It really showed qualities any science communicator should have: carefulness, skepticism, courage to admit what does not know nor understand, and honesty. It also showed how discussions should be made. Thank you.

Is there a reason the EM drive hasn't been replicated more? It seems fairly simple and inexpensive for a university that has the right equipment (vacuum chambers and whatnot), so seems like it would be a handy experiment for publishing a paper in a few weeks, or as an assignment for later year undergrads.

Update: since this video was filmed, the EM drive is believed to not actually work. The measured thrust is from interference from the Earth’s magnetic field, according to an experiment by Technische Universität Dresden in Germany, May 2018.

Similar to this idea: put small wheels on the front of a car, large ones on the back. The car will think it's on a hill, and start to accelerate. You've made a dragster! The big noisy engines are to impress the chicks.

Officially changed my major from Electrical Engineering to Physics (Astrophysics) I AM HYPE!

I trust this guy much more than Thunderf00t.

You're easily the channel with the highest scientific standard on RU-vid. You're so accurate; I wish other creators would discuss such high level subjects in such an entertaining way. Long story short: Great work, you do! Keep it up!

Hey Space Time! I'm so glad there are teams like yours out there educating and debunking sensationalist press regarding any scientific experiment. Please never stop doing the amazing job you do! The world needs you. 💞

This is what I like the most about PBS Space Time. Their approach isn't too technical and is definitely layman-friendly but isn't too misrepresentative or too misleading like contemporary "pop sci" institutions (I'm looking at you IFLS). Kudos to everyone involved!

Here's my hypothesis: This is the highest quality chanel on youtube. Observable evidence: - open to all possible ideas and contributions - intellectual honesty - usage of scientific methodology - grain of salt toward not conclusive novelty - every single topic well researched... - and even better explained... - ... without distorting simplifications - engaged community built around chanel (e.g +TheGamingg33k just officially changed his major from Electrical Engineering to Physics (Astrophysics)) Although other potential explanation has to be ruled out (below), I dare you to disprove my hypothesis! Alternative explanations: - I've slept 3 today and my cognitive abilities are altered - I am secretly homosexual and therefore possibly biased - I've eaten my favourite meal during this episode and in reality this post is about superiority of braised shrimp in garlic sauce over other meals Keep up great work!

I'm glad that their were resources available to write a paper like this. I know it would have been great to see them test all the different possibilities for a false positive but just getting the time to run an experiment like this is awesome. With the world of science being so much about getting published it seems like it is hard for people to take a chance on things that would fly in the face of established physics. Coming up with crazy ideas and figuring out you are wrong is just as worthwhile for science as to follow the predictable path.

Question about Quantum entanglement and the theory of relativity. What would happen if you take 2 entangled particles and place 1 in a lab on earth and shoot another towards a black hole. Would the entangled particle on earth change states faster as the other reaches the black hole or would it slow down as its partner reaches the black hole? Or does relativity even apply to entangled particles as maybe the particle heading towards the black hole would be affected by the particle on earth thus would match the speed of the particle on earth. Don't know why i'm thinking of this, it kinda just popped in my head.

Can people stop saying that produces insignificant thrust to be worth anything? You are forgetting the big picture. 1. If this actually works, it may open a new field of study which may lead to even greater discoveries. 2. (Again, assuming that this actually works) The one used in the Eagle Works experiment was just for proof of concept. They admitted themselves that it was not engineered to be optimized. It was also very small compared to what would be used in a real space ship. 3. This a completely foreign type of technology. Once we figure out how it is actually making thrust then we may be able to make it actually efficient. Compare it to the first computers. They took 10s of seconds just to multiply TWO numbers. In other words, they were actually good for nothing. Fast forward decades of research and investment and we have technology that changed human civilization forever.

Matt I want you know if you ever wrote a Sci Fi book, we would all but it. Edit: Buy

I have to say that I really appreciate how this channel simplifies things without completely dumbing it down. So glad to see something somewhat understandable and pretty informative without all the hype, voodoo, and click bait content.

+PBS Space Time A simple test you could do to see if it really works would be to simply "open" the "big end" of the EM drive up so it acts like a regular photon thruster. If the thrust levels stay the same as the "closed" EM drive, then you know that the drive doesn't actually work, and there is some other phenomenon at play. If you open it up and the thrust drops to just a photon thruster level of thrust, then you know that somehow the drive is creating actual thrust.

Sometimes I often wonder, what are we missing? I've heard a blind individual (since birth) talk about colors, he said "How can a pen and the sky both be blue? I don't get it." When I heard that, I thought about what we could potentially be missing. Not being able to sense things has a huge impact on how we see/make sense of it. We have our senses and are comfortable with them, confident they give us all the information required to piece our environment together, but if we were a species that had no vision - using a different sense to "see" the world (Sonar for example), would we still be just as confident? Our brain is limited and one day our science will hit a wall - anything past that point won't make any sense and I would blame that on our brains capability to comprehend or sense information. So what if we're potentially missing something entirely? For example, a blind guy knows the object exists, he can feel it and imagine a shape in his brain, but he can't imagine what it visually looks like, colors, etc. What if thats the same with us? Like Dark Matter for example, something is affecting the galaxies and we can see the effect, but thats it. What if its something huge that would be very obvious to us if we had the senses to detect it? We do have instruments to detect things we can't sense, but thats due to us being able to sense some of it to begin with - like light. We can't see Infrared, Ultraviolet, Xrays, etc, but because we can see Visible light it made us curious and we had a lead, we were able to find out that this frequency can be increased/decreased, etc. Hey, call me crazy, call me wrong, disagree, its just a thought. There may be something we're missing entirely at the moment because its outside our comprehension and maybe we're starting to get a peak at it via these crazy experiments like the EM Drive. Then again, maybe not. We're all hopeful to discover brand new physics which could potentially open up a whole new can of worms, but its unlikely at this point it seems. I truly believe our next advancement in science will not derive from a human being, but from Artificial Intelligence - and the scary thing is, that discovery may be beyond what we can ever understand. Another great video! Its always exciting to see one of these videos pop up on my subscription list!

Can we get more Journal Club? I loved it.

So refreshing to see intelligent comments and no arguing. This is just amazing. Go smart people.

Holy crap. No crappy superior/dismissive/scoffing attitude. It's an actual serious treatment of a controversial topic. Bless you, Matt.

EM drives - burn up kilowatts of power for almost no thrust!!!! Woot!

This episode took a very good approach to a contraversial topic.

5:30 I'm with you on that one, Matt. That's pretty lousy to assume a linear relationship between thrust and power from those data (a whopping _three_ data points, two of which are statistically the same?), and then proceed from there with claims about a thrust-to-power ratio of 1.2 mN per kW. If they really want to show that it follows a linear relationship, they should take more data at different power levels, and especially see if that supposed linear relationship remains true when extended to higher power levels.

As a person who works in the science field I wish to greatly thank you very much for such a thorough and grounded discussion. I really appreciate how well you focused on what we do know, the theories underlining the science. And perhaps most importantly giving a detailed brief on where errors could arise. Unfortunately in most scientific publications I sometimes feel that the discussion on the possibility of error and the Madrid ways they can crop up and effect the experiment isn't covered nearly enough. Especially covering a great deal of content targeted at the general public, who often misunderstand error in a scientific context. As error can. and often does arise with even the most experienced and competent researchers. Again great work, please keep it up.

It's always a nice feeling when you see a PBS Spacetime thumbnail in your sub feed.

"Stop broadcasting, you're in danger!" hahaha I like that, nice one Ryan :)

FINALLY, I agree with this channel on fact vs. theory. PBS tends to release theory as fact, this new break down of possible errors in measurement is exactly how I feel/think about the EM drive phenomena. Please do MORE of this when it comes to origin of the universe theory, hyperinflation, and all other unproven but highly speculative theories! The CMB doesn't prove or dial in the 'actual' age of the universe, we don't know HOW the things at scale translate!

"Stop broadcasting you're in danger" comments gave me chills.. That sounds like a GREAT SciFi story.

Real Talk: we've avoided the topic of the EM drive because most of the data coming out isn't reliable, and because it's become a topic for conspiracy theorists and r/futurology... Not sure which is worse.

I like how everyone is so dismissive of the drive. It's always a snarky, head shaking explanation of why it won't work followed by why it could work. Everyone is always so entrenched in their views, regardless if they're arguing about politics or quantum field theory (especially so with the latter it seems).

Beautiful video. This is what journalism is. Real quality. This video could teach news students in school on how it's done.

Channels like PBS Space Time are better as they give us reliable and plausible explanation on sensitive topics like the one in the video above. We are all really great full of people who spend their time and energy to explain others and spread the topics aiding in the advancement of science and technology, inspiring young generation to research or study in the vast field of science.

Can we just take one of the built EM Drives and stick some solar panels on it and toss it out the ISS airlock? If the thing goes zooming off into space constantly accelerating, we'll know it works!

Is it real? Em... I don't think so.

The internet Cafe at the center of the galaxy. I can totally see Douglas Adams writing a wacky adventure about it, I bet it would have been great lol.

Kudos to the introduction of a journal club style RU-vid presentation. I'm glad this channel produces the smart content it does.

Spacetime comments are the best comments. Not this one though. This one is pretty bad.

The first rule of Spacetime Journal Club is...

Perhaps they should add a Flux Capacitor.

The EM Drive will work for one very important reason - because I so very badly want it to work. Otherwise, I can't see any way it ever could. ☹️

holy fuck that ryan messed me up

I think the person saying that aliens wouldn't use radio was actually referring to its near uselessness as a means for interstellar communication. It is just way too slow for any civilization that might have achieved interstellar capabilities. Not that they wouldn't develop the technology at all. It is why sci-fi writers use the idea of subspace, tachyons, etc. for communication over interstellar distances. I've thought that possibly gravity waves or something like that might work, assuming that the fabric of space doesn't have the light speed limitation, which I'm guessing it doesn't. So if gravity waves could be modulated like radio waves, well then maybe that could transmit at interstellar distances faster than light, since only the fabric of space itself would be 'moving', and not photons or anything else on the electromagnetic spectrum. I just figure that if we can actually detect them, we should eventually be able to replicate them. Of course we should be getting closer to warp drive at that point, even if only sub-luminal at first. Or maybe it wouldn't work, but it sounds good.

After 1 year still this is the best video about EM drive....kudos to you

It's interesting that the narrator mentions Jim Woodward's criticism of Shawyer's theory. What's not mentioned is that Woodward also proposes a propellent-less drive based on the Mach effect. There is evidence for Woodward's device generating thrust also. Some scientists think that the EMDrive may be generating thrust also by the Mach effect.

The EM drive will be capable of traveling through space at incredible speeds. As soon as it can develop enough thrust to lift it's own research paper.

420 views and 42 likes i am the chosen one

journal club is one of the best things to ever happen I wish more channels did journal clubs

"Stop broadcasting, you're in danger." I'm pretty sure that novel has already been written, and it won a Hugo award.

This notification squad tho...

The Force confirmed, I am going to become a Jedi now.

You are very enlightning. I cant do all these calculations,but thanks to people like you,i Can follow the great Lines . Even explain some of it to my pals. So cary on. So thanks..

While the topic was EM Drives, it may as well have been "How to Construct and Criticize an Academic Paper." Kudos to the break down of each element that goes into the thorough examination of the practical application of an EM Drive, and all the potential confounding variables that may have impacted the results of the particular study analyzed.

"Stop broadcasting you're in danger" imagine getting THAT message from an alien civilization.

Hey dude, I love your stuff. I do however have a little gripe with the idea that if there are no limits to intellectual growth, but at some point we can understand roughly what can and can't be done in the universe. I think looking back to before the 1920's, many thought physics was a done deal, then quantum opened up another big layer to the onion. thanks :)

Love PBS and the new channel! First of all the EM drive looks backwards - the "force side" is bigger than the concentrate side. In classical analysis I would expect the wave pattern to concentrate waves directed through a smaller rather than larger orifice! Given the sparse info we have this would not appear to contravene any claims the EM drive makes! I'm a chemist not a physicist however I have had my head bent, hurt, twisted on the ozone layer. I survived then I was subjected to the twisted world of Einstein, Heisenburg, Bohr, Penrose et al. and Quantum mechanics I haven't given up as I did pursue X-ray-crystallography and to this day understand something of what you talk. X-ray-crystallography is an observed verses a model science; yes it is now a service product. However, the principle is the same record then model and model an agreement factor! I'm not good enough to suggest a thought experiment as the great 1! I only hope I am good enough to ask a question which is worthy of your consideration.

Dissapointed: I was expecting the paper to be rejected with reviewer comments of the form: "I am dissapointed that I did not find a citation to by O'Dowd et al. "

That was very diplomatic, Matt. I can't say I would've been as generous in your place... and in fact, I wasn't! And to be honest that entire "error sources" section to me looked like something that was added to the paper after the fact after some hounding by referees. It's quite disjointed and the reasons given don't make a great deal of sense. "Vibration can't cause a steady state displacement"... but it totally can, though :) Given certain past statements by H. White I also wouldn't discount the possibility of fraud. He was arguing about conservation of energy violations in propellantless thrusters and tried to say that the same problems arise for conventional rockets. He tried to argue that above a certain speed you get more energy than you put in even with something like a Hall thruster... except, of course, you don't, but he said that the "change" in kinetic energy was more than you put in :) That's something I find I hard to interpret charitably. (see my video circa 6 30 for details)

I think you may have been beaten to the punch Matt :P "Three Body Problem" by Liu Cixin is a great exploration of the "Stop broadcasting, you are in danger" idea. (It's really good, and I definitely recommend reading it if you're interested in the idea)

I must say, I have always enjoyed the videos from Space Time channel. Really interesting stuff especially to someone who likes space and everything related into it.

A little after the NASA group published their results, there was a paper published (can't find it now) explaining a possible mathematical theory behind it, also based on Pilot Wave Theory. One of the interesting things is that the theory lines up with all tests and results so far, which cover several different configurations and power levels, and suggest that most of the tests have been done at nearly the worst possible configuration for optimal power efficiency. IFF (notice the large letters and double F) this is correct, it would mean a simple re-configuration should produce comparatively much larger thrusts (thus harder to explain as a false positive). More testing is still needed, but for those of us in the science community willing to accept that maybe we don't understand QUANTUM PHYSICS quite as well as we thought (I mean, just look at the Higg's Bosom mass results), this is kind of exciting. P.S. Thanks for doing a good, fair, balanced analysis of this paper. Could you maybe do one covering the other various experiments and their results/possible errors/etc?

thunderf00t and pbs spacetime busted this. I can rest peacefully.

Now that Vsauce is more or less dead, this is my favorite channel on youtube. I just liked Vsauce better because of the way the episodes were written, directed, and narrated, which was really genius and entertaining, like storytelling mixed with science. Vsauce was a uinique experience (not Vsauce2 or 3, only Michael's channel counts).

Thank you for an excellent series, brilliantly presented. I've been looking for science that doesn't dumb things down. This is a challenging series of videos and very much appreciated. Cheers!

I hope that you guys keep on doing this series. This video is an excellent lesson on scientific skepticism.

I'm still waiting for cold fusion, dang it! I want my flying DeLorean!

WOO! Under 10 views!

Respect to Space Time for sticking to facts and not going down the tempting click-baity headline route!

first 20 secs and this guys got me hooked yet again. said it once and I'll say it again, he has the best body language I've seen

As others have said Thunderf00t did a really solid takedown of this device. It's particularly good because the video shows the completely insane claims those behind it make: For example that we'll have flying cars using EM Drives...

It's silly for people to draw a firm conclusion on inconclusive data. A few more tests will confirm it one way or another. If our curiosity was sated with "Everything we know tells us this is wrong" then we would still believe that gods controlled all aspects of the world... well okay bad example.

Please, I want to see a popular physics based or general science channel talk about turbulence and how do we ridiculously lack knowledge about understanding it. No channel in youtube seems to cover this topic. I mean, there are great channels with amazing styles on making videos about highly difficult science branches but not even one on turbulence? I know that even a brief introduction to turbulence requires many levels of math and physics knowledge. And I would like to assume that science channels deliberately avoid it due to its complexity. I remember some videos trying to explain it without all that difficult stuff, but they were not effective and couldn't invoke the excitement I was expecting out of them. But as far as I can tell, you guys deal here with seriously hard topics if not harder than turbulence. So I tend to think that you can pull this off. I'm just a new starting phd student on turbulence modeling and it is my passion to learn more about it. Even more so to see this brilliant subject being interpreted from scientist, experts etc. I don't know maybe I'm too childish with my expectation. But think about it, it is most probably our new door in science waiting to be opened. Turbulence being related to chaos, self similar behaviors, emerging patterns out of randomness, strange mathematical properties resulting from the simplest of equations etc. etc. I am no youtuber or a frequent video uploader or an expert to talk on this, but even I can see how an amazing video concept turbulence can be. Maybe doing a video directly about turbulence might not be in your schedule. But you can do for example small introductions to those fields, e.g. classical mechanics, fluid dynamics etc. Demanding it, is completely different than actually doing it, I am very well aware of that. And even if you take my suggestion seriously, I know it depends on many other factors. But right perturbation in right space and time may lead to much greater changes in the system, I just hope my perturbation would be enough to invoke bigger dynamics :) I almost become like a fan girl on this whole turbulence thing :D I hope you take my message seriously. Amazing channel by the way, I can hardly describe its beauty.

As a graduate student in statistics, I love seeing how it gets used in other disciplines. I was especially excited that it was the focus of a critique of this study. I have two questions regarding the scatterplot of the data with the linear curve: 1) Is there a scientific/physical reason for expecting a linear relationship between thrust and power? 2) The error bars (if that's what they are) are throwing me off a little bit. They must not be standard error bars because averages ought to have smaller standard errors than individual data measurements. I'm just a bit at a loss for their purpose. I also want to echo the sentiments of many other people commenting on this video; it is wonderful to see science be communicated so clearly and without the sensationalist bent that seems to plague typical scientific news outlets.

It’s nice to see someone who hasn’t been hoodwinked by some eggheads electric drum

I can answer this rather quickly. After reading the paper: Fantasy

Got to give it to you For the depth with which the subject matter was presented 🙏🙏🙏

I love the idea of finding a universal internet 13:50 Maybe the first thing we will discover is we can all sign up to SpaceBook :)

It always seems strange to me when something as simple as heating the device and testing for false positives hasn't been tried yet. Like, I understand that there's a fair amount of preparation involved in any testing, but, why wait so long?

YET! Not powerful enough for hoverboards YET! :-)

A suggestion for a test of the EM Drive. This is quite a rather sticky subject in physics today. There are allot of hypothesis on why exactly the EM Drive produced thrust in some tests. Many would be hard to detect like atomic sized metal residue left in the chamber or some form of ionization of the surfaces of the chamber that would produce photons. All of those would take very extensive monitoring and detection.Now the interesting on is that the shape of the magnetic field creates some type of malformation of the pilot waves. That is the most interesting concept and probably the easiest to test. So exactly how would one go about testing that hypothesis? The answer would be to reconstruct the chamber using a superconductor and thereby facilitating the Meissner Effect in order to reshape the magnetic field. One would think that it would improve the efficiency of the EM Drive, the magnetic field has to go somewhere and the law of the conservation of energy would seem to indicate that a force would be applied to the chamber wall. If that doesn’t work, then it is probably one of the more mundane explanations.

Ryan's comment had kept me up for an hour so far...

The first message we get from aliens will be "Stop broadcasting! We're getting tired of I Love Lucy."

A physics friend of mine said the EM drive is total BS. She used an analogy similar to the car one you used. She thinks it's junk science and that not all other alternative explanations were explored for such a low thrust and that their data is within the margin of error.

I just found this channel great presentation . While it would be great to state "look what we found" it is far better to think and respond than react nice work

I was just thinking about you guys making a video about the EM Drive today.

Set the speed of the video to 1.25x and it sounds like he's talking normally

This is how science should be done. Put a claim to the test3. Rule out mundane explanations. Most of the time the claim will be found to be untenable. Every once in a while, we might make new science. What should be avoided is to decide the issue without testing it. The explanations given fot the EM drive do not agree with known physics. However, all current physical knowledge was once in conflict with the physics of the time. My guess is that this effort is a result of well-known laws of physics. But you just never know... And you won't ever know, if you aren't open to new ideas.

If I'm not mistaken the thrust is produced at the ''thin'' end not the ''fat'' end of the cavity resonator. Introduction to Harold White paper, you cite, states on the very first page, as follows: ''It is shown here, that a dielectrically loaded, tapered RF article excited in the transverse magnetic 212 (TM212) mode .... at 1937 MHz is capable of consistently generating force directed to the narrow end under vacuum condition.'' Page 3 fig.2 also shows the net thrust as directly opposite, to the one you visualize at the beginning of the presentation (2:10). You then present this very diagram later at 4:02 without as much as a blink of an eye. Consistency and scrupulous approach to a scientific subject are of paramount importance here, I guess.

I liked the Cal Tech analogy, if Shoyer is saying thrust is created by differing radiation pressure on each end, let's get two people in a car to push on the front and rear windows, no matter whether it's two babies, a baby and the world's strongest man, or a baby and ten of the World's strongest men, no amount of differential pressure is going to push the car forwards or backwards.

It's tunneling of one of an entangled pair.

Turn playback speed to 1.25x --> Matt's voice sounds normal. wtf?

Always a good sign when your objective analysis starts with an attitude of skepticism.

I found your channel today and I just couldn't stop watching. Keep up the amazing work.

EM Drive is the Trump of Science

uh wrong. The Delorean time machine takes 2.21 jigowatts!!!

Maybe the explanation is the Alcubierre-White warp drive acting on a much smaller scale than was originally proposed. The microwaves are setting up standing waves that must send the chamber cone walls into microscopic oscillations, thus also acting to warp spacetime at a very minute level.

The next journal entry should be about the new theory that Gravity might not be a fundamental property of the Universe but an emergent property.