9 ms·

Wow. My gut tells me something is wrong here, and that this is being mismeasured. However, this would be an enormous breakthrough if it pans out, even at the lo

by daeken 12y ago

Wow. My gut tells me something is wrong here, and that this is being mismeasured. However, this would be an enormous breakthrough if it pans out, even at the low levels NASA has seemingly confirmed. We're very good at generating power in space; solar is basically infinite in the inner parts of our solar system, and we have a lot of experience with RTGs and other power generation mechanisms. If we can directly turn power into thrust without burning fuel in the process, this truly changes everything. But as I said, I think this will end up not panning out for one of these reasons: 1) The microwaves bouncing around cause a small amount of material to be lost and be sent out of the device, causing the thrust. 2) The RF in play is throwing off detection (this, to me, seems most likely -- it could explain the thousandfold difference in detected thrust levels between the Chinese and US tests). 3) Some sort of effect that is linked to gravity. No idea what, though. I really look forward to further testing. Edit: Given that I'm terrible with the scale of small numbers, I decided to do some quick math. If you were to use that thrust of 50 micronewtons to drive the Voyager spacecraft (722kg) full out for one year from a starting velocity of 0m/s, you would end up at 0.0911259m/s at the end of the year. By comparison, Voyager is currently traveling at 17km/s.

asuffield 12y ago
Given that it has so far been detected as working by two independent organisations that tried very hard to get the test right, some new science has clearly been done here. We don't yet have clear evidence that it's a new propulsion technology, as it's possible that what has been discovered is an entirely new mechanism for confounding measurement instruments, but that does not lessen the scientific value of this discovery. There is new knowledge here. Perhaps new physics. I slightly wish I was a physicist so that I could go and find out.
- josu 12y ago
  >two independent organisations Sorry, but one of them being Chinese, I would say that there is only one reliable source, and the chances that they made a mistake are high.
  - gambiting 12y ago
    Are you saying that no good science can be made in China purely because it's China? USSR sometimes lied about their results,but they had scientists just as good as the US did. I have little doubt that good science can be done in China too.
    - josu 12y ago
      Nope, I am saying that Chinese science is not reliable. I'm not saying that they lie about all their science, or that no good science is done in China. But when you have to go with your gut, and there are only two sources and one of them is Chinese, I would never reach a conclusion such as: "some new science has clearly been done here"
      - enraged_camel 12y ago
        >>Nope, I am saying that Chinese science is not reliable Why not?
        davorak 12y ago
        From the Chinese graduate students and professors that I have talked to the problems seems to be that it is really is to commit fraud and get a way with it. In particular in some fields you can get rich writing grants, getting a considerable amount of money and writing fake papers. There is a heavy temptation for many to do the same when all of their colleges are able to buy multiple houses and live an extravagant life style. An example from ~5-9 years ago would be a Chinese professor flying to California and buying a multi million dollar vacation house in cash. This is an extreme example and was uncommon even at the time. My understanding is that this is not the case in all fields, it is easier to get a way with fraud in the less hard sciences supposedly. I also have read about several efforts over the last several years to try and correct matters. It is also the case that many papers written by non-native english speakers suffer from grammar and spelling errors. Unfortunately incorrect grammar and or spelling often has a negative halo effect for many on the scientific content of the paper. There is plenty of good science that comes out of China, however it suffers from a negative halo effect from the above sources.
- XorNot 12y ago
  The Chinese tests did not include testing in a VACUUM. Not a sealed chamber, but an actual, airless, gasless, box of some sort. The power levels involved in these devices are 10-20 kW - that much power into anything is capable of heating air and producing currents from convection alone. A microwave cavity is exactly the sort of thing which would make a great make-shift reaction chamber for a very inefficient, very ordinary jet engine of some sort. I note the Wired article here also makes no mention of whether they tested the device in a vacuum chamber. Its the only test which matters, and no one ever does it, meanwhile they're pumping enough wattage to flash boil water around things. EDIT: From the NASA abstract as well - "Testing was performed on a low-thrust torsion pendulum that is capable of detecting force at a single-digit micronewton level, within a stainless steel vacuum chamber with the door closed but at ambient atmospheric pressure." Given what this thing claims to do, and how you have to operate it (allegedly) and the scale of the forces involved (tiny), not testing in an actual, evacuated vacuum chamber is absurd.
  - daveloyall 12y ago
    If the microwave chamber is sealed air tight, they might need to construct a special one before they can test it in vacuum. But yes, they should get on that!
  - gnarbarian 12y ago
    That much current would also create a magnetic field radiating out from the wiring. Maybe the force is that of the interaction between the earth's magnetic field and the microwave. IANAP
    - JulianMorrison 12y ago
      They tested with an RF load to look for that kind of effect.
  - scottlocklin 12y ago
    If it ain't tested in a vacuum, it's almost certainly simple coronal discharge.
api 12y ago
It would alter our understanding of physics, so it would be both scientific and technological. From what I understand it would move our understanding of everything even further from classical Newtonian physics and deeper into the relativity/quantum dichotomy realm. This thing could only have a relativistic macroscopic explanation and a quantum mechanical microscopic one. Classically it's impossible. One immediate consequence of a massless drive is that interstellar flight becomes far more "thinkable." It's not like we could build a starship tomorrow, but if this worked and if you could build a power plant (fusion?) capable of running a big one long enough, you could practically accelerate to meaningful fractions of the speed of light. Hell... I wonder if fission would be sufficient if you no longer had to take propellant? All that propellant mass could be plutonium instead, and you "burn" it slowly and jettison the spent fuel to progressively reduce your mass and increase your acceleration. Side note: if this keeps getting confirmed, the Fermi paradox becomes even more paradoxical. "They should be here." The impracticality of interstellar flight disappears as an excuse. If this effect is possible, something is clearly wrong. Either life itself is edge-of-impossibility improbable and most of the cosmos is sterile, we are the most advanced/complex life in the galaxy, or they are here and they're not communicating with us, or something even weirder.
- marcosdumay 12y ago
  This engine does not change the energy needed for interstelar travel, only reaction mass, and reaction mass is often free with an energy generator, because all of them waste some mass. If this thing is confirmed, it will be a much more significative scientific breakthrough than a technological one. That said, there is no reason for interestelar travel not to be viable. It's just too expensive for us with our current tech.
  - XorNot 12y ago
    Reaction mass is definitely not free. You can get a lot of energy by a number of means, but the need to haul an ever increasing quantity of reaction mass for every bit of delta-v you want is the limiting factor. If you did not have to haul any reaction mass, then delta-v is limited solely by energy. Which means you can take some solar panels and thrust indefinitely up to light speed, with a vessel weighing a couple of kilos as opposed to megatons.
skriticos2 12y ago
NASA is running out of fuel (Plutonium) for RTG's and no new fuel is produced. http://www.isciencetimes.com/articles/6087/20130919/nasa-plutonium-problem-deep-space-exploration-battery.htm http://www.isciencetimes.com/articles/6087/20130919/nasa-plu...
- daeken 12y ago
  The plutonium shortage in NASA really has nothing to do with technology or science, but just politics. We simply stopped producing the stuff, but we could start again at any time; as the article you linked mentions, we're planning on doing so.
  - sgt101 12y ago
    There's enough plutonium to make 10,000 nukes stored in the Sellafield facility in Cumbria, England http://www.independent.co.uk/news/uk/vaults-will-store-the-nuclear-seeds-of-10000-nagasakis-more-than-half-of-the-worlds-stocks-of-plutonium-will-be-held-at-sellafield-by-the-end-of-the-century-1539730.html http://www.independent.co.uk/news/uk/vaults-will-store-the-n... So, there is no storage.
    - maxerickson 12y ago
      It isn't that simple: http://en.wikipedia.org/wiki/Plutonium-238#Production http://en.wikipedia.org/wiki/Plutonium-238#Production Of course a program could be spun up to actually do the separation, but I think it might be sort of expensive.
    - imdsm 12y ago
      I've been there as a child, if I'd have known that, I probably wouldn't have gone.
- astrodust 12y ago
  It's impossible to run out of plutonium so long as uranium fuelled reactors are running. It's a common by-product of the fission process. It maybe be harder or impractical for them to get it or process it, but saying "no new fuel is produced" is false
DenisM 12y ago
19 thousand years.
- daeken 12y ago
  Woops, you're right! I was doing some ballpark math a couple orders of magnitude higher thrust, to see what would be practical if this were scaled up. (For context, my original post said that matching Voyager's velocity would take 19 years.)
pavel_lishin 12y ago
What happens after two, five and ten years?
- Lambdanaut 12y ago
  It should increase linearly.
  - TheCraiggers 12y ago
    Keep in mind that a linear speed increase is still a non-linear distance increase over time.
oldmanjay 12y ago
Voyager used gravity assist to achieve its current velocity, so the comparison isn't 100% fair. A craft with this drive can certainly avail itself of that technique as well.
- daeken 12y ago
  Oh, for sure. It's by no means an apples-to-apples comparison (just being in orbit around Earth before you start your journey out gives you a huge jump on that), just gives you a sense of scale.
- sehugg 12y ago
  Other deep-space spacecraft make use of non-trivial delta-v, around 200/300 m/s for some maneuvers: https://space.stackexchange.com/questions/4054/delta-v-of-deep-space-maneuvers-in-deep-space-missions-like-voyager-or-pioneer https://space.stackexchange.com/questions/4054/delta-v-of-de...
pocketstar 12y ago
Voyager is only traveling at 17km/s because of orbital maneuvers. These thrusters would probably not be used for delta-v. However, they would be great for reliable attitude control. Currently attitude is controlled with reaction wheels, small fuel based thrusters or magnetorquers or some combination. Reaction wheels fail, fuel based thrusters run out of fuel, and magnetorquers are weak.
darkmighty 12y ago
Let's not forget a similarly ellusive case which lasted quite long: http://en.wikipedia.org/wiki/Pioneer_anomaly http://en.wikipedia.org/wiki/Pioneer_anomaly Although admitedly this thruster can undergo much more testing.
lnanek2 12y ago
It's not a breakthrough in science at all, honestly. It is already well known that you can propel something just by generating photons (generally using nuclear power to heat an element, just like a light bulb). Microwaves are just a different wavelength. It is just too inefficient to matter at the moment. The only breakthroughs to be made are in efficiency. Photons still have energy and momentum, just no rest mass, and there is even such a thing as electromagnetic pressure created from photons transferring momentum.
- DennisP 12y ago
  It's true you can generate thrust by throwing photons out one end, but that's not what this device does. It bounces microwaves around inside a closed, superconducting chamber, with one end wider than the other.
  - hliyan 12y ago
    Exactly right. It's an apparent violation of Newton's Third Law, unless the photons are pushing against virtual particle pairs as suggested in the article.
    - madaxe_again 12y ago
      It's not a violation from the reference frame of the rf - just yours.
  - tehwalrus 12y ago
    Oh, it's that device? The one that was on the cover of New Scientist at some point? We (i.e. the lecturer) mocked that in physics lectures (mostly on a "look at the shit New Scientist publishes..." sidetrack). It may also have claimed perpetual motion, while it was at it. If there really is some quantum interaction, then this becomes interesting, but from momentum alone the contributions from the sides of the box always exactly cancel the resultant from the mismatched plates (by definition of a closed box).
    - 12y ago
pmalynin 12y ago
I don't know where you got those numbers from. Momentum of an object is equal to mass times velocity. Change in momentum is equal to impulse, which is force times time. Therefore f * t = mv, and change in v = f * t / m. Plugging in the numbers, (0.00005 N) * (3600s/hour * 24 hours * 365 days) / (722 kg) = 2.18 m/s
Tloewald 12y ago
Your first explanation was my immediate thought -- but I assume they at least checked for this (if it's obvious to a high school physics type such as myself). I would assume that an actual thruster would be a bit bigger than the test unit!
kghose 12y ago
Combining with the comments below, there is a note that the test worked even when they changed a vital configuration (seemed to be a control test). When a control fails, the conclusion is that the experiment is buggy and you need to rethink things. Unfortunately, it seems from the article, the conclusion was that some new physics was at work here.

by daeken 12y ago

asuffield 12y ago

Given that it has so far been detected as working by two independent organisations that tried very hard to get the test right, some new science has clearly been done here. We don't yet have clear evidence that it's a new propulsion technology, as it's possible that what has been discovered is an entirely new mechanism for confounding measurement instruments, but that does not lessen the scientific value of this discovery. There is new knowledge here. Perhaps new physics. I slightly wish I was a physicist so that I could go and find out.

josu 12y ago
>two independent organisations Sorry, but one of them being Chinese, I would say that there is only one reliable source, and the chances that they made a mistake are high.
- gambiting 12y ago
  Are you saying that no good science can be made in China purely because it's China? USSR sometimes lied about their results,but they had scientists just as good as the US did. I have little doubt that good science can be done in China too.
  - josu 12y ago
    Nope, I am saying that Chinese science is not reliable. I'm not saying that they lie about all their science, or that no good science is done in China. But when you have to go with your gut, and there are only two sources and one of them is Chinese, I would never reach a conclusion such as: "some new science has clearly been done here"
    - enraged_camel 12y ago
      >>Nope, I am saying that Chinese science is not reliable Why not?
      - davorak 12y ago
        From the Chinese graduate students and professors that I have talked to the problems seems to be that it is really is to commit fraud and get a way with it. In particular in some fields you can get rich writing grants, getting a considerable amount of money and writing fake papers. There is a heavy temptation for many to do the same when all of their colleges are able to buy multiple houses and live an extravagant life style. An example from ~5-9 years ago would be a Chinese professor flying to California and buying a multi million dollar vacation house in cash. This is an extreme example and was uncommon even at the time. My understanding is that this is not the case in all fields, it is easier to get a way with fraud in the less hard sciences supposedly. I also have read about several efforts over the last several years to try and correct matters. It is also the case that many papers written by non-native english speakers suffer from grammar and spelling errors. Unfortunately incorrect grammar and or spelling often has a negative halo effect for many on the scientific content of the paper. There is plenty of good science that comes out of China, however it suffers from a negative halo effect from the above sources.
XorNot 12y ago
The Chinese tests did not include testing in a VACUUM. Not a sealed chamber, but an actual, airless, gasless, box of some sort. The power levels involved in these devices are 10-20 kW - that much power into anything is capable of heating air and producing currents from convection alone. A microwave cavity is exactly the sort of thing which would make a great make-shift reaction chamber for a very inefficient, very ordinary jet engine of some sort. I note the Wired article here also makes no mention of whether they tested the device in a vacuum chamber. Its the only test which matters, and no one ever does it, meanwhile they're pumping enough wattage to flash boil water around things. EDIT: From the NASA abstract as well - "Testing was performed on a low-thrust torsion pendulum that is capable of detecting force at a single-digit micronewton level, within a stainless steel vacuum chamber with the door closed but at ambient atmospheric pressure." Given what this thing claims to do, and how you have to operate it (allegedly) and the scale of the forces involved (tiny), not testing in an actual, evacuated vacuum chamber is absurd.
- daveloyall 12y ago
  If the microwave chamber is sealed air tight, they might need to construct a special one before they can test it in vacuum. But yes, they should get on that!
- gnarbarian 12y ago
  That much current would also create a magnetic field radiating out from the wiring. Maybe the force is that of the interaction between the earth's magnetic field and the microwave. IANAP
  - JulianMorrison 12y ago
    They tested with an RF load to look for that kind of effect.
- scottlocklin 12y ago
  If it ain't tested in a vacuum, it's almost certainly simple coronal discharge.

api 12y ago

It would alter our understanding of physics, so it would be both scientific and technological. From what I understand it would move our understanding of everything even further from classical Newtonian physics and deeper into the relativity/quantum dichotomy realm. This thing could only have a relativistic macroscopic explanation and a quantum mechanical microscopic one. Classically it's impossible. One immediate consequence of a massless drive is that interstellar flight becomes far more "thinkable." It's not like we could build a starship tomorrow, but if this worked and if you could build a power plant (fusion?) capable of running a big one long enough, you could practically accelerate to meaningful fractions of the speed of light. Hell... I wonder if fission would be sufficient if you no longer had to take propellant? All that propellant mass could be plutonium instead, and you "burn" it slowly and jettison the spent fuel to progressively reduce your mass and increase your acceleration. Side note: if this keeps getting confirmed, the Fermi paradox becomes even more paradoxical. "They should be here." The impracticality of interstellar flight disappears as an excuse. If this effect is possible, something is clearly wrong. Either life itself is edge-of-impossibility improbable and most of the cosmos is sterile, we are the most advanced/complex life in the galaxy, or they are here and they're not communicating with us, or something even weirder.

marcosdumay 12y ago
This engine does not change the energy needed for interstelar travel, only reaction mass, and reaction mass is often free with an energy generator, because all of them waste some mass. If this thing is confirmed, it will be a much more significative scientific breakthrough than a technological one. That said, there is no reason for interestelar travel not to be viable. It's just too expensive for us with our current tech.
- XorNot 12y ago
  Reaction mass is definitely not free. You can get a lot of energy by a number of means, but the need to haul an ever increasing quantity of reaction mass for every bit of delta-v you want is the limiting factor. If you did not have to haul any reaction mass, then delta-v is limited solely by energy. Which means you can take some solar panels and thrust indefinitely up to light speed, with a vessel weighing a couple of kilos as opposed to megatons.

skriticos2 12y ago

NASA is running out of fuel (Plutonium) for RTG's and no new fuel is produced. http://www.isciencetimes.com/articles/6087/20130919/nasa-plutonium-problem-deep-space-exploration-battery.htm http://www.isciencetimes.com/articles/6087/20130919/nasa-plu...

daeken 12y ago
The plutonium shortage in NASA really has nothing to do with technology or science, but just politics. We simply stopped producing the stuff, but we could start again at any time; as the article you linked mentions, we're planning on doing so.
- sgt101 12y ago
  There's enough plutonium to make 10,000 nukes stored in the Sellafield facility in Cumbria, England http://www.independent.co.uk/news/uk/vaults-will-store-the-nuclear-seeds-of-10000-nagasakis-more-than-half-of-the-worlds-stocks-of-plutonium-will-be-held-at-sellafield-by-the-end-of-the-century-1539730.html http://www.independent.co.uk/news/uk/vaults-will-store-the-n... So, there is no storage.
  - maxerickson 12y ago
    It isn't that simple: http://en.wikipedia.org/wiki/Plutonium-238#Production http://en.wikipedia.org/wiki/Plutonium-238#Production Of course a program could be spun up to actually do the separation, but I think it might be sort of expensive.
  - imdsm 12y ago
    I've been there as a child, if I'd have known that, I probably wouldn't have gone.
astrodust 12y ago
It's impossible to run out of plutonium so long as uranium fuelled reactors are running. It's a common by-product of the fission process. It maybe be harder or impractical for them to get it or process it, but saying "no new fuel is produced" is false

DenisM 12y ago

19 thousand years.

daeken 12y ago
Woops, you're right! I was doing some ballpark math a couple orders of magnitude higher thrust, to see what would be practical if this were scaled up. (For context, my original post said that matching Voyager's velocity would take 19 years.)

pavel_lishin 12y ago

What happens after two, five and ten years?

Lambdanaut 12y ago
It should increase linearly.
- TheCraiggers 12y ago
  Keep in mind that a linear speed increase is still a non-linear distance increase over time.

oldmanjay 12y ago

Voyager used gravity assist to achieve its current velocity, so the comparison isn't 100% fair. A craft with this drive can certainly avail itself of that technique as well.

daeken 12y ago
Oh, for sure. It's by no means an apples-to-apples comparison (just being in orbit around Earth before you start your journey out gives you a huge jump on that), just gives you a sense of scale.
sehugg 12y ago
Other deep-space spacecraft make use of non-trivial delta-v, around 200/300 m/s for some maneuvers: https://space.stackexchange.com/questions/4054/delta-v-of-deep-space-maneuvers-in-deep-space-missions-like-voyager-or-pioneer https://space.stackexchange.com/questions/4054/delta-v-of-de...

pocketstar 12y ago

Voyager is only traveling at 17km/s because of orbital maneuvers. These thrusters would probably not be used for delta-v. However, they would be great for reliable attitude control. Currently attitude is controlled with reaction wheels, small fuel based thrusters or magnetorquers or some combination. Reaction wheels fail, fuel based thrusters run out of fuel, and magnetorquers are weak.

darkmighty 12y ago

Let's not forget a similarly ellusive case which lasted quite long: http://en.wikipedia.org/wiki/Pioneer_anomaly http://en.wikipedia.org/wiki/Pioneer_anomaly Although admitedly this thruster can undergo much more testing.

lnanek2 12y ago

It's not a breakthrough in science at all, honestly. It is already well known that you can propel something just by generating photons (generally using nuclear power to heat an element, just like a light bulb). Microwaves are just a different wavelength. It is just too inefficient to matter at the moment. The only breakthroughs to be made are in efficiency. Photons still have energy and momentum, just no rest mass, and there is even such a thing as electromagnetic pressure created from photons transferring momentum.

DennisP 12y ago
It's true you can generate thrust by throwing photons out one end, but that's not what this device does. It bounces microwaves around inside a closed, superconducting chamber, with one end wider than the other.
- hliyan 12y ago
  Exactly right. It's an apparent violation of Newton's Third Law, unless the photons are pushing against virtual particle pairs as suggested in the article.
  - madaxe_again 12y ago
    It's not a violation from the reference frame of the rf - just yours.
- tehwalrus 12y ago
  Oh, it's that device? The one that was on the cover of New Scientist at some point? We (i.e. the lecturer) mocked that in physics lectures (mostly on a "look at the shit New Scientist publishes..." sidetrack). It may also have claimed perpetual motion, while it was at it. If there really is some quantum interaction, then this becomes interesting, but from momentum alone the contributions from the sides of the box always exactly cancel the resultant from the mismatched plates (by definition of a closed box).
  - 12y ago

pmalynin 12y ago

I don't know where you got those numbers from. Momentum of an object is equal to mass times velocity. Change in momentum is equal to impulse, which is force times time. Therefore f * t = mv, and change in v = f * t / m. Plugging in the numbers, (0.00005 N) * (3600s/hour * 24 hours * 365 days) / (722 kg) = 2.18 m/s

Tloewald 12y ago

Your first explanation was my immediate thought -- but I assume they at least checked for this (if it's obvious to a high school physics type such as myself). I would assume that an actual thruster would be a bit bigger than the test unit!

kghose 12y ago

Combining with the comments below, there is a note that the test worked even when they changed a vital configuration (seemed to be a control test). When a control fails, the conclusion is that the experiment is buggy and you need to rethink things. Unfortunately, it seems from the article, the conclusion was that some new physics was at work here.