Do you have adblock enabled?
 
If you can read this, either the style sheet didn't load or you have an older browser that doesn't support style sheets. Try clearing your browser cache and refreshing the page.

(Wired UK)   Propellant-less microwave thruster to the left, physics flame-war to the right   ( wired.co.uk) divider line
    More: Unlikely, microwaves, physics, electrohydrodynamic thruster, new space, propulsion systems, space researches, propellants, aeronautics  
•       •       •

2805 clicks; posted to Geek » on 08 Feb 2013 at 10:10 AM (4 years ago)   |   Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»



77 Comments     (+0 »)
 
View Voting Results: Smartest and Funniest


Oldest | « | 1 | 2 | » | Newest | Show all

 
2013-02-08 10:20:46 AM  
Me before reading article: Eh, it's a translated paper, probably they're just talking about some kind of photon-driven drive, i.e. one with no physical, massive propellant as such.  Those are actually being researched several places and found to be pretty goo--

Shawyer aimed to develop an EmDrive: a closed, conical container which, when filled with resonating microwaves, experiences a net thrust towards the wide end. It seems to violate of the law of conservation of momentum, implied by Newton, which says that no closed system can have a net thrust. However, Shawyer says net thrust occurs because the microwaves have a group velocity which is greater in one direction than the other and Einstein's relativity comes into play.

Oh, so it's a perpetual motion machine.  Not only that, it's a perpetual motion machine that not only has no third-party reproduction, it's a perpetual motion machine that didn't even pass the relatively light peer review to get published in an actual scientific journal, and he was reduced to publishing in the Chinese Academy of Sciences periodical, which has less credibility in the world of Science than the McDonald's dollar menu, because with the dollar menu you still learn nothing true or useful but at least can gain reasonably-priced coffee.
 
2013-02-08 10:23:45 AM  
Luminiferous aether?
 
2013-02-08 10:23:55 AM  
My reaction was "well, maybe...." right up until I saw the inventor has plans for a flying car.

Never trust anyone trying to sell you a flying car.
 
2013-02-08 10:27:42 AM  

Jim_Callahan: Not only that, it's a perpetual motion machine that not only has no third-party reproduction


FTFA: However, the EmDrive cannot violate the law of conservation of energy. It can exert force, but accelerating a vehicle over a distance still requires a huge amount of power

Perpetual motion machines do not require "huge amount of power ". There are certainly reasons to be skeptical here but you are off base.
 
2013-02-08 10:31:29 AM  

Cthulhu_is_my_homeboy: My reaction was "well, maybe...." right up until I saw the inventor has plans for a flying car.

Never trust anyone trying to sell you a flying car.


They said the same thing about flying tanks.  Then the Air force showed them the A-10.
 
2013-02-08 10:33:55 AM  
None of them actually inspected the apparatus, but Shawyer was assailed from all sides online and in the science press. Criticism was unsophisticated: Newton said it was impossible, therefore he must be a fraud

Most scientists are so ignorant and close-minded that you'd swear you were interacting with creationists.
 
2013-02-08 10:35:42 AM  

Farking Canuck: Jim_Callahan: Not only that, it's a perpetual motion machine that not only has no third-party reproduction

FTFA: However, the EmDrive cannot violate the law of conservation of energy. It can exert force, but accelerating a vehicle over a distance still requires a huge amount of power

Perpetual motion machines do not require "huge amount of power ". There are certainly reasons to be skeptical here but you are off base.


It's positing that a standing wave can exert more force in one direction than another.  It's a perpetual motion machine, in at least the functional aspect.

Albeit I was using the term more as a catch-all for "making up something blatantly untrue, putting it in quasi-scientific terms, and trying to sell it to people as the way of the future" than being literal, but if you're wanting to be literal I'm still technically (i.e. the best kind of) correct.

Neener neener.
 
2013-02-08 10:36:17 AM  

Jim_Callahan: Me before reading article: Eh, it's a translated paper, probably they're just talking about some kind of photon-driven drive, i.e. one with no physical, massive propellant as such.  Those are actually being researched several places and found to be pretty goo--

Oh, so it's a perpetual motion machine.


It is a photon drive.  Microwaves are photons, too.

/ Doesn't mean it works
 
2013-02-08 10:38:00 AM  
Any Chinese farkers want to take a stab at a translation?
cdni.wired.co.uk
 
2013-02-08 10:38:31 AM  

enik: None of them actually inspected the apparatus, but Shawyer was assailed from all sides online and in the science press. Criticism was unsophisticated: Newton said it was impossible, therefore he must be a fraud

Most scientists are so ignorant and close-minded that you'd swear you were interacting with creationists.


www.troll.me
 
2013-02-08 10:40:35 AM  

Jim_Callahan: Farking Canuck: Jim_Callahan: Not only that, it's a perpetual motion machine that not only has no third-party reproduction

FTFA: However, the EmDrive cannot violate the law of conservation of energy. It can exert force, but accelerating a vehicle over a distance still requires a huge amount of power

Perpetual motion machines do not require "huge amount of power ". There are certainly reasons to be skeptical here but you are off base.

It's positing that a standing wave can exert more force in one direction than another.  It's a perpetual motion machine, in at least the functional aspect.

Albeit I was using the term more as a catch-all for "making up something blatantly untrue, putting it in quasi-scientific terms, and trying to sell it to people as the way of the future" than being literal, but if you're wanting to be literal I'm still technically (i.e. the best kind of) correct.

Neener neener.


No, you are not Humpty Dumpty or Bill Clinton and cannot redefine a word to cover your knee-jerk reaction.
 
2013-02-08 10:47:41 AM  

Macular Degenerate: Any Chinese farkers want to take a stab at a translation?
[cdni.wired.co.uk image 620x413]


It appears to be a deep-fryer with a system to automatically recirculate the oil.
 
2013-02-08 10:49:53 AM  

Jim_Callahan: Farking Canuck: Jim_Callahan: Not only that, it's a perpetual motion machine that not only has no third-party reproduction

FTFA: However, the EmDrive cannot violate the law of conservation of energy. It can exert force, but accelerating a vehicle over a distance still requires a huge amount of power

Perpetual motion machines do not require "huge amount of power ". There are certainly reasons to be skeptical here but you are off base.

It's positing that a standing wave can exert more force in one direction than another.  It's a perpetual motion machine, in at least the functional aspect.

Albeit I was using the term more as a catch-all for "making up something blatantly untrue, putting it in quasi-scientific terms, and trying to sell it to people as the way of the future" than being literal, but if you're wanting to be literal I'm still technically (i.e. the best kind of) correct.

Neener neener.


 Perpetual motion machines are supposed to be closed systems that can run forever without outside input. This thing would require large amounts of energy being pumped into it. It may or may not work, but it ain't a perpetual motion machine.
 
2013-02-08 10:50:06 AM  

enik: Most scientists are so ignorant and close-minded that you'd swear you were interacting with creationists.


As a general rule, when someone proposes an idea that's contrary to everything we know about how forces work, it's pretty safe to dismiss the idea out of hand. If the idea has merit, then it will collect data to support it, and you can eat your crow later.
 
2013-02-08 10:50:49 AM  

SomeTexan: It is a photon drive.  Microwaves are photons, too.

/ Doesn't mean it works


Well, a traditional photon drive (if you can call tech that young "traditional")  emits photons, it doesn't stick them in a closed box and gain momentum from them with the power of wishful thinking.  But, yeah, I guess.

natazha: No, you are not Humpty Dumpty or Bill Clinton and cannot redefine a word to cover your knee-jerk reaction.


I didn't redefine shiat.  It claims to gain momentum from a system that by definition does not produce momentum.  That's a perpetual motion machine, whether it's leaky and requires refresh from an emitter or not.
 
2013-02-08 10:50:57 AM  

Macular Degenerate: Any Chinese farkers want to take a stab at a translation?


s18.postimage.org
 
2013-02-08 10:55:46 AM  
Instead of wasting time with this, just use a solar sail.
 
2013-02-08 10:56:06 AM  

jfarkinB: Macular Degenerate: Any Chinese farkers want to take a stab at a translation?

[s18.postimage.org image 620x413]


Brilliant!
 
2013-02-08 11:00:20 AM  

Macular Degenerate: Any Chinese farkers want to take a stab at a translation?
[cdni.wired.co.uk image 620x413]


I'll take a swing at it...

i.imgur.com
 
2013-02-08 11:00:45 AM  

Jim_Callahan: Farking Canuck: Jim_Callahan: Not only that, it's a perpetual motion machine that not only has no third-party reproduction

FTFA: However, the EmDrive cannot violate the law of conservation of energy. It can exert force, but accelerating a vehicle over a distance still requires a huge amount of power

Perpetual motion machines do not require "huge amount of power ". There are certainly reasons to be skeptical here but you are off base.

It's positing that a standing wave can exert more force in one direction than another.  It's a perpetual motion machine, in at least the functional aspect.

Albeit I was using the term more as a catch-all for "making up something blatantly untrue, putting it in quasi-scientific terms, and trying to sell it to people as the way of the future" than being literal, but if you're wanting to be literal I'm still technically (i.e. the best kind of) correct.

Neener neener.


It ain't perpetual and there is no motion.  You fail on both counts.
 
2013-02-08 11:03:57 AM  
Slashdot covered it yesterday.
 
2013-02-08 11:09:51 AM  

Jim_Callahan: Me before reading article: Eh, it's a translated paper, probably they're just talking about some kind of photon-driven drive, i.e. one with no physical, massive propellant as such.  Those are actually being researched several places and found to be pretty goo--

Shawyer aimed to develop an EmDrive: a closed, conical container which, when filled with resonating microwaves, experiences a net thrust towards the wide end. It seems to violate of the law of conservation of momentum, implied by Newton, which says that no closed system can have a net thrust. However, Shawyer says net thrust occurs because the microwaves have a group velocity which is greater in one direction than the other and Einstein's relativity comes into play.

Oh, so it's a perpetual motion machine.  Not only that, it's a perpetual motion machine that not only has no third-party reproduction, it's a perpetual motion machine that didn't even pass the relatively light peer review to get published in an actual scientific journal, and he was reduced to publishing in the Chinese Academy of Sciences periodical, which has less credibility in the world of Science than the McDonald's dollar menu, because with the dollar menu you still learn nothing true or useful but at least can gain reasonably-priced coffee.


I like how science is an open-minded search for the truth. Like the warm reception it gave for the idea that ulcers were caused by Helicobacter Pylori.
 
2013-02-08 11:10:47 AM  
Even the most advanced theoretical critique, produced by John Costella, a PhD in relativistic electrodynamics, amounted to arguing about the direction of an arrow on one of Shawyer's diagrams.

I'm guessing that was the arrow that said that this particular closed system will go from more entropy → less entropy?
 
2013-02-08 11:24:51 AM  

Marcus Aurelius: Jim_Callahan: Farking Canuck: Jim_Callahan: Not only that, it's a perpetual motion machine that not only has no third-party reproduction

FTFA: However, the EmDrive cannot violate the law of conservation of energy. It can exert force, but accelerating a vehicle over a distance still requires a huge amount of power

Perpetual motion machines do not require "huge amount of power ". There are certainly reasons to be skeptical here but you are off base.

It's positing that a standing wave can exert more force in one direction than another.  It's a perpetual motion machine, in at least the functional aspect.

Albeit I was using the term more as a catch-all for "making up something blatantly untrue, putting it in quasi-scientific terms, and trying to sell it to people as the way of the future" than being literal, but if you're wanting to be literal I'm still technically (i.e. the best kind of) correct.

Neener neener.

It ain't perpetual and there is no motion.  You fail on both counts.


I don't know if this thing works or not, but like you I don't find "perpetual motion machine, therefore neener neener" to be exactly a compelling argument.

However, what many Farkers may not realize is that "conservation of momentum, therefore fail" is also not a killing argument. In a nutshell, the naive concept of conservation of momentum can be violated when electromagnetic fields and charged particles are involved -- for example, the drive posited here. I was going to type up an elaborate example, but it turns out Richard Feynman already did it much better, as cited here:

Feynman gives a simple example, two charged particles, one moving directly towards the other and the other one moving in some other random direction (not towards the first). The electric forces are nearly equal and opposite (up to relativistic corrections that are lower order) and the magnetic force (the first relativistic correction to the Newton's third law consistent Coulomb repulsion) is only nonzero on one of the particles, since there is no magnetic field along the line of motion by symmetry.

When relativistic effects matter -- and in particular any time electromagnetism is in play -- momentum is not conserved in the naive sense of Newton's Third Law. Instead you have to consider a more complex quantity called the stress-energy-momentum tensor (also known as the energy-momentum tensor or stress-energy tensor).

TL; DR: I don't know whether this thing works or not, but it's a mistake to simply dismiss it. The alleged principle of operation violates neither conservation of energy nor conservation of momentum, properly understood.
 
2013-02-08 11:24:57 AM  
Actually, it makes sense. You have cone shaped cavitation chamber the microwaves is propogated at one end, and it's added to along it's length so by the time it leaves the chamber it's larger than it started, pushing against the entire chamber in the process. Makes sense. And it would work best in space. Don't see what the problem is. Why is everyone so willing to lock themselves into absolutes? I guess that's the difference between creating and created.
 
2013-02-08 11:26:22 AM  

jjorsett: I like how science is an open-minded search for the truth. Like the warm reception it gave for the idea that ulcers were caused by Helicobacter Pylori.


Sure, the scientific process is a sham. That's why to this day everyone ridicules the notion that H. pylori causes ulcers.

Cranks who claim to have reactionless drives have had a long time to Show Everyone. All you have to do is hang it in a vacuum chamber and demonstrate that it pushes in one direction without expelling any reaction mass.

Still waiting.
 
2013-02-08 11:31:08 AM  
jjorsett:
I like how science is an open-minded search for the truth. Like the warm reception it gave for the idea that ulcers were caused by Helicobacter Pylori.


Welcome to science.

Sorry if you get offended by thoughtful, critical comments and questions, but that's how science greets _every_ idea (http://en.wikipedia.org/wiki/Falsifiability). The ideas that stand up to scrutiny (like bacterial causes of ulcers, or continental drift) then become a part of the established knowledge base. Then a new idea comes along, and is challenged because it disagrees with the new basis of tested theory until it too can be supported by data. And so on.
 
2013-02-08 11:34:39 AM  

indarwinsshadow: Makes sense


What you said actually makes absolutely no sense, but that's okay.

indarwinsshadow: I guess that's the difference between creating and created.


No, it's SCIENCE!

When someone says, "Hey, guys, I have this new toy that operates in contradiction to principles long established," the correct answer is, "Smells like bullshiat."

It doesn't mean it is bullshiat. It just means it smells like it. The final answer comes, as always, from experiments. If the idea is valid, then it'll work, no matter what anybody thinks on the matter. Or, to put it another way:
Well controlled experimental results or GTFO.

Remember the time the CERN folks detected faster-than-light signals? And it turned out that they had a misconfiguration in one of their GPS timing systems? Occam's Razor applied then, and it applies now. Given the choice between the discovery of a completely new mechanism of propulsion or the chance that this guy just screwed up (or is actively defrauding people), the <i>simplest</i> explanation is that he's a farkup (or fraud). farkups and frauds are common. Entirely new physics are rare.
 
2013-02-08 11:35:43 AM  

czetie: However, what many Farkers may not realize is that "conservation of momentum, therefore fail" is also not a killing argument. In a nutshell, the naive concept of conservation of momentum can be violated when electromagnetic fields and charged particles are involved -- for example, the drive posited here. I was going to type up an elaborate example, but it turns out Richard Feynman already did it much better, as cited here:

Feynman gives a simple example, two charged particles, one moving directly towards the other and the other one moving in some other random direction (not towards the first). The electric forces are nearly equal and opposite (up to relativistic corrections that are lower order) and the magnetic force (the first relativistic correction to the Newton's third law consistent Coulomb repulsion) is only nonzero on one of the particles, since there is no magnetic field along the line of motion by symmetry.


<goes off to read cited page>

<comes slinking back in despair>

I give up. Pretty sure I don't even understand "field momentum"; quite sure I don't understand "flow of momentum density". Can't even keep Lagrangians and Hamiltonians straight. I'm out of the fight.

It sure would be cool if the drive turns out to work. I remain pessimistic.
 
2013-02-08 11:40:03 AM  
Looking at the diagram it looks like he is expecting a thrust because a point emmission is working on a larger area than the opposite side.  That does not work in an enclosed case.
 
2013-02-08 11:46:54 AM  

jfarkinB: Cranks who claim to have reactionless drives have had a long time to Show Everyone. All you have to do is hang it in a vacuum chamber and demonstrate that it pushes in one direction without expelling any reaction mass.

Still waiting.


If you read TFA you will find that "demonstrating thrust" is exactly what two independent labs claim to have done. (Proving it's not a spurious effect from other sources is harder, of course, considering the low levels of thrust involved).

Again, I'm not saying that this thing definitely works. However, the general principle does not violate fundamental physical laws. The proposal is closer to "sailing dead downwind faster than the wind" than "cold fusion": it sounds counterintuitive, but it's not prima facie physically impossible, and knee-jerk dismissal is not justified.
 
2013-02-08 11:51:54 AM  

czetie: I don't know if this thing works or not, but like you I don't find "perpetual motion machine, therefore neener neener" to be exactly a compelling argument.

However, what many Farkers may not realize is that "conservation of momentum, therefore fail" is also not a killing argument. In a nutshell, the naive concept of conservation of momentum can be violated when electromagnetic fields and charged particles are involved -- for example, the drive posited here. I was going to type up an elaborate example, but it turns out Richard Feynman already did it much better, as cited here:
...

When relativistic effects matter -- and in particular any time electromagnetism is in play -- momentum is not conserved in the naive sense of Newton's Third Law. Instead you have to consider a more complex quantity called the stress-energy-momentum tensor (also known as the energy-momentum tensor or stress-energy tensor).

TL; DR: I don't know whether this thing works or not, but it's a mistake to simply dismiss it. The alleged principle of operation violates neither conservation of energy nor conservation of momentum, properly understood.



I clicked on your link, then clicked on it's link to the discussion on Newton's law, which stated that when "no external forces act on a system, its total momentum is conserved". The article claims that this is true even in light of relativistic effects.

The drive does posit a violation of this principle, at least according to the article. I think this merits skepticism, much like the skepticism that a new perpetual motion machine should face.
 
2013-02-08 11:54:32 AM  

t3knomanser: Given the choice between the discovery of a completely new mechanism of propulsion or the chance that this guy just screwed up (or is actively defrauding people), the <i>simplest</i> explanation is that he's a farkup (or fraud). farkups and frauds are common. Entirely new physics are rare.


In fairness, he's not claiming entirely new physics. He's claiming an interesting new application of an established principle perfectly consistent with Relativity theory. Whether it works in practice is another question. Sometimes an idea gets unfairly dismissed because it superficially sounds like something known not to work. Sometimes it gets dismissed because the field is filled with hopeless cranks. Sometimes it even gets dismissed because the Grand Old Man of the field rejects it, and the idea has to wait for him to die to have its time.

And sometimes an idea gets dismissed because it's flat out wrong, like cold fusion.

However, as you say the proof is in the pudding. If the Chinese can actually thrust a satellite using this mechanism, it won't matter how little any of us like it.
 
2013-02-08 11:54:39 AM  

draypresct: jjorsett:
I like how science is an open-minded search for the truth. Like the warm reception it gave for the idea that ulcers were caused by Helicobacter Pylori.


Welcome to science.

Sorry if you get offended by thoughtful, critical comments and questions, but that's how science greets _every_ idea (http://en.wikipedia.org/wiki/Falsifiability). The ideas that stand up to scrutiny (like bacterial causes of ulcers, or continental drift) then become a part of the established knowledge base. Then a new idea comes along, and is challenged because it disagrees with the new basis of tested theory until it too can be supported by data. And so on.


Really, you're passing off falsification as Science?
 
2013-02-08 12:02:19 PM  

t3knomanser: indarwinsshadow: Makes sense

What you said actually makes absolutely no sense, but that's okay.

indarwinsshadow: I guess that's the difference between creating and created.

No, it's SCIENCE!

When someone says, "Hey, guys, I have this new toy that operates in contradiction to principles long established," the correct answer is, "Smells like bullshiat."

It doesn't mean it is bullshiat. It just means it smells like it. The final answer comes, as always, from experiments. If the idea is valid, then it'll work, no matter what anybody thinks on the matter. Or, to put it another way:
Well controlled experimental results or GTFO.

Remember the time the CERN folks detected faster-than-light signals? And it turned out that they had a misconfiguration in one of their GPS timing systems? Occam's Razor applied then, and it applies now. Given the choice between the discovery of a completely new mechanism of propulsion or the chance that this guy just screwed up (or is actively defrauding people), the <i>simplest</i> explanation is that he's a farkup (or fraud). farkups and frauds are common. Entirely new physics are rare.


You don't understand the basics of how a microwave is created?

Good explanation.
http://www.instructables.com/id/MICROWAVE-RADIATION/step4/producing- mi crowaves/

Outside of that, I'm not sure what your confusion is. It's propellantless. Not reactionless. Two different terms my friend.
 
2013-02-08 12:04:31 PM  
I liked the space tether idea better. It has the added benefit of already being tested in orbit. Just run the tether out and instead of capturing power from it, send power down it to increase velocity.
 
2013-02-08 12:06:44 PM  

jfarkinB: I give up. Pretty sure I don't even understand "field momentum"; quite sure I don't understand "flow of momentum density". Can't even keep Lagrangians and Hamiltonians straight. I'm out of the fight.


Here's a potentially useful math-free analogy:

Think of the EM field itself as a kind of sponge that can you can squeeze and flex and twist and then allow to spring back. As you "stress" the sponge it stores energy (and, in a sense, momentum). Very loosely speaking, the system swaps momentum (in the naive sense) of the object for deformation in the EM field, and then expels that deformation out the back of the cavity (which is asymmetrical, which is why there is thrust in one direction). [Note: this description is materially wrong in every significant way, but it might convey the sense of what's going on]

It sure would be cool if the drive turns out to work. I remain pessimistic.

This, and that. Just pointing out that it's an overreaction to dismiss this out of hand.
 
2013-02-08 12:08:57 PM  

Ivo Shandor: Slashdot covered it yesterday.


You're either a certified genius or an authentic wacko....
 
2013-02-08 12:14:11 PM  
Gravity can only be explained by its effect, physics has yet to explain the mechanism. Is the Higgs  Field a stationary field throughout the universe? Is it a field that is moving in all directions simultaneously? Until we know for certain how gravity actually works, how can we say that it can't be deflected like a sailboat tacking into the wind?
 
2013-02-08 12:30:45 PM  

draypresct: I clicked on your link, then clicked on it's link to the discussion on Newton's law, which stated that when "no external forces act on a system, its total momentum is conserved". The article claims that this is true even in light of relativistic effects.


Yes, but you have to understand "momentum" correctly. This drive violates the naive "Newton's 3rd Law" concept of momentum conservation, but not stress-energy-momentum conservation as properly formulated.

The same is true of Feynman's simple Two Charged Particles example above: it violates Newtonian momentum conservation, but not "proper" momentum conservation. That makes it profoundly counterintuitive, especially since most of us have never even been exposed to this extended idea of momentum, but not impossible.

The drive does posit a violation of this principle, at least according to the article. I think this merits skepticism, much like the skepticism that a new perpetual motion machine should face.

No, it merits skepticism much like "sailing downwind faster than the wind" should face, or the claim of the discovery of a new high-temperature superconductor would face.

A perpetual motion machine violates physical principles so profoundly fundamental that it could only work if the laws of physics vary over time. If a perpetual motion machine worked, it would be utterly astonishing that anything else does. That's an extremely high barrier of credibility to cross.

By contrast, this proposal does not violate any such established physical principles; but it does propose to exploit a mechanism that requires understanding beyond a typical physics education (heck, even most introductory undergraduate level physics courses don't teach this stuff, AFAIK).

I wish I had the ability to explain this more clearly without bogging down in the math, but unfortunately I don't.
 
2013-02-08 12:33:18 PM  

MarkEC: Gravity can only be explained by its effect, physics has yet to explain the mechanism. Is the Higgs  Field a stationary field throughout the universe? Is it a field that is moving in all directions simultaneously? Until we know for certain how gravity actually works, how can we say that it can't be deflected like a sailboat tacking into the wind?


General Relativity models gravity just fine. We probably don't have the tools yet to experiment with gravity on a fundamental level. Who knows, maybe the person that can merge the Standard Model and General Relativity has already been born. I'm not holding my breath though. Part of me thinks that there is something about gravity that extends into a dimension that we can't manipulate - hence, we are unable to pinpoint the method of force interaction. The idea of a graviton is cool, but just seems like a cludge.
 
2013-02-08 01:05:25 PM  

draypresct: The drive does posit a violation of this principle, at least according to the article. I think this merits skepticism, much like the skepticism that a new perpetual motion machine should face.


...which is not the same thing as preemptive dismissal, but does demand that the proposer had better have a good demonstration.
 
2013-02-08 01:10:23 PM  

Nurglitch: draypresct: jjorsett:
I like how science is an open-minded search for the truth. Like the warm reception it gave for the idea that ulcers were caused by Helicobacter Pylori.


Welcome to science.

Sorry if you get offended by thoughtful, critical comments and questions, but that's how science greets _every_ idea (http://en.wikipedia.org/wiki/Falsifiability). The ideas that stand up to scrutiny (like bacterial causes of ulcers, or continental drift) then become a part of the established knowledge base. Then a new idea comes along, and is challenged because it disagrees with the new basis of tested theory until it too can be supported by data. And so on.

Really, you're passing off falsification as Science?


I wrote "that's how science greets _every_ idea (link to falsification)".
How did you get "science = falsification" out of that?

Would you mind giving me some indication as to whether you're just trolling, or whether there was some actual breakdown in communication?
 
2013-02-08 01:34:19 PM  

czetie: draypresct: I clicked on your link, then clicked on it's link to the discussion on Newton's law, which stated that when "no external forces act on a system, its total momentum is conserved". The article claims that this is true even in light of relativistic effects.

Yes, but you have to understand "momentum" correctly. This drive violates the naive "Newton's 3rd Law" concept of momentum conservation, but not stress-energy-momentum conservation as properly formulated.

The same is true of Feynman's simple Two Charged Particles example above: it violates Newtonian momentum conservation, but not "proper" momentum conservation. That makes it profoundly counterintuitive, especially since most of us have never even been exposed to this extended idea of momentum, but not impossible.


Feynman's example, while interesting for its own sake (and a good exercise for anybody who's going through Jackson's Classical Electrodynamics, as he sets the same trap in a few homework problems), is a red herring here.  The supposed machine's fields are confined to a finite region and it operates in a steady state, so tracking the changes in the electromagnetic momentum is a very simple task.  If you take snapshots of the system at two different times, you see exactly the same fields inside and no fields outside (and thus no change in the momentum component of the stress-energy), but supposedly the thing's momentum has changed.  That doesn't work.
 
2013-02-08 01:44:13 PM  

MarkEC: Until we know for certain how gravity actually works, how can we say that it can't be deflected like a sailboat tacking into the wind?


And who can say that it isn't actually made of fairies? Little gravity gnomes hold objects together. I mean, if we're just going to talk out our asses, lets have some fun with it!
 
2013-02-08 01:45:46 PM  

Maestro1701: Ivo Shandor: Slashdot covered it yesterday.

You're either a certified genius or an authentic wacko....


what? They don't build em like this anymore?
 
2013-02-08 01:50:10 PM  
I think this development has a potential for explosive growth. An exponential expansion of power into thrust.

I cant wait to see a SPR EMDrive in action!
 
2013-02-08 01:55:39 PM  

The Beatings Will Continue Until Morale Improves: Instead of wasting time with this, just use a solar sail.


The article about the solar sail a few days ago mentioned substantially less thrust than this device.  Also, the thing that always struck me as odd about solar sails -- how are you going to get back towards the sun?  You can't tack in space.  Tacking only works in water because of the friction between the hull of the boat and the water itself.  Without that friction, you can't go up wind.
 
2013-02-08 02:03:32 PM  

meanmutton: The Beatings Will Continue Until Morale Improves: Instead of wasting time with this, just use a solar sail.

The article about the solar sail a few days ago mentioned substantially less thrust than this device.  Also, the thing that always struck me as odd about solar sails -- how are you going to get back towards the sun?  You can't tack in space.  Tacking only works in water because of the friction between the hull of the boat and the water itself.  Without that friction, you can't go up wind.


You turn the sail so it reflects light toward the direction you're orbiting (approximately, anyway --  the idea is to thrust against your direction of travel).  That doesn't force you toward the sun, but it reduces your orbital velocity and allows gravity to do the job.  Orbital mechanics can be pretty counter-intuitive at first, but spend a few days reading up on it (and/or playing Kerbal Space Program) and it will make sense.
 
2013-02-08 02:25:30 PM  

kg2095: PirateKing: Macular Degenerate: Any Chinese farkers want to take a stab at a translation?
[cdni.wired.co.uk image 620x413]

I'll take a swing at it...

Having visited China last month I can say that China may even be more capitalist than the US.


That's what they WANT you to think.
 
Displayed 50 of 77 comments


Oldest | « | 1 | 2 | » | Newest | Show all


View Voting Results: Smartest and Funniest

This thread is archived, and closed to new comments.

Continue Farking
Submit a Link »
On Twitter





Top Commented
Javascript is required to view headlines in widget.

In Other Media
  1. Links are submitted by members of the Fark community.

  2. When community members submit a link, they also write a custom headline for the story.

  3. Other Farkers comment on the links. This is the number of comments. Click here to read them.

  4. Click here to submit a link.

Report