EM drive

[ArchimedesBoy]

Ok, I have been hearing about the EM(Electromagnetic) drive, and I heard that NASA and Eagleworks labs explanation for the mysterious thrust is a different interpretation of quantum physics, that electrons do have an certain place at a certain time. Can anyone give me any more information about this?

 

For those that don't know;

The EM drive is an engine designed for space travel that runs on the theory that when microwaves are put into a cone-shaped enclosed tank(sorry if that isn't the right word, I'm very tired right now. I had a long night.) it creates thrust. So far the research has been successful, and the EM drive is consistently producing 1.2mN/kW, with hopes to get it to 60mN/kW

[Bender]

To me it rises above the usual crackpot theories for several reasons:

- they do not violate any conservation laws. As far as I understand the explanation, the drive obeys conservation of momentum by pushing off virtual particles.

- the results are confirmed in a carefully executed and controlled experiment by reputable scientists at NASA

- they actually have a theory about how it works that seems to make some sense, although I must admit that's not my area of expertise and I don't fully understand it.

 

All this warants further research, but I still won't put too much money on it actually working. The results were really tiny, and the setup was not accurate enough to be conclusive. Thermal influences were quite large, even if they were compensated for. The setup was also insufficiently damped.

Edited March 11, 2017 by Bender

[ArchimedesBoy]

Thanks for the response, but I was actually asking not for an explanation of the EM drive, I've done my research on that, but on the theory about electrons. Thank you for answering!

[imatfaal]

1. It does violate conservation of momentum - if it is the one I have seen it is reactionless which means violation; this, in turn, means it does not work.

 

2. The empirical data is not just not conclusive it is clear where large errors have been made, proper techniques not followed, and failure to move above the level of confirmation bias.

 

3. Whilst experimental data is king - it is desirable that there is a theoretical basis; even more so that it doesn't upset the basis of all modern physics.

 

If you have data which are more conclusive then please post a link / abstract. But the level of "thrust" produced is just so minimal that you must be doing this in vacuo, your results must be properly significant, and it will be repeated (and must be repeatable) as this is Nobel Prize territory.

[Bender]

1. It does violate conservation of momentum - if it is the one I have seen it is reactionless which means violation; this, in turn, means it does not work.

 

2. The empirical data is not just not conclusive it is clear where large errors have been made, proper techniques not followed, and failure to move above the level of confirmation bias.

 

3. Whilst experimental data is king - it is desirable that there is a theoretical basis; even more so that it doesn't upset the basis of all modern physics.

 

If you have data which are more conclusive then please post a link / abstract. But the level of "thrust" produced is just so minimal that you must be doing this in vacuo, your results must be properly significant, and it will be repeated (and must be repeatable) as this is Nobel Prize territory.

Are you referring to these experiments, published in the Journal of Propulsion and Power by NASA-affiliated scientists? You might be referring to earlier experiments, since these were made in a vacuum.

They also have a theoretical basis, but I cannot judge the validity myself. I would be interested in your insights.

Edited March 12, 2017 by Bender

[imatfaal]

Are you referring to these experiments, published in the Journal of Propulsion and Power by NASA-affiliated scientists? You might be referring to earlier experiments, since these were made in a vacuum.

They also have a theoretical basis, but I cannot judge the validity myself. I would be interested in your insights.

 

You are correct - I was referring to older experiments. That's a lot of reading to do... will revert

 

The last set of experiments were pretty dreadful - these at least seem to be in vacuo and have a result that is different from the null.

[imatfaal]

Are you referring to these experiments, published in the Journal of Propulsion and Power by NASA-affiliated scientists? You might be referring to earlier experiments, since these were made in a vacuum.

They also have a theoretical basis, but I cannot judge the validity myself. I would be interested in your insights.

 

Sometimes you have to wonder about NASA.

 

That paper is a bit of a shambles; huge swathes of missing information (calculation of frequency and modes) , virtually no data (as far as I can tell they ran 18 tests - WTF? 1800 would be more like the number), still absolutely no real theory to back it up (there is no model let alone a theory which could be tied into to modern physics), bad technique (they use a hand held camera for thermal analysis - that thing is only gonna accurate to one part in a hundred or so!) , attempts to replicate at other places have drawn a null result.

 

They may be something going on - personally I doubt it because it requires a rewriting of the law of conservation of momentum - but this paper is not going to convince anyone. Hopefully, some real experimentalists can make it a project and either provide a good significant result or put it to bed (for all but the crackpots) for ever

[Bender]

Thank you for your insights. I think it has to be viewed as a relatively low-budget proof of concept experiment.

[imatfaal]

Thank you for your insights. I think it has to be viewed as a relatively low-budget proof of concept experiment.

 

NASA have a bit of a reputation in this sphere - they were involved in various bits of the nickel/copper cold energy scam; I even think they had a hand in the arsenic based life-form farago.

 

One cannot tell from the paper but it seems as if the "tuning" and setting of frequencies which took a huge amount of time might be interpreted (by a hardhearted observer) as a set-up designed to allow confirmation bias; ie if you only measure when you have your tuning right, and your tuning is only right when you observe a desired thrust, then all your measurement will show a thrust - but you hve proved nothing.

 

And from all accounts this paper was the result of many years of work - not a quick proof of concept. The "proof of concept" was the previous paper which was so full of holes you could see straight through. Great leaps come from allowing guys like this to play - but we must be careful to not get carried away; mad experiments are brilliant but accepting insignificant results from sloppy metholdology is just silly.

 

If tuning is important to thrust generation then the method is simple. Build a double ended device - identical in every way except right hand side is tuned, left hand side is not tuned; hang it on a string such that when turned off it hangs straight - turn it on. No worries with thermals as both sides will be heated equally

[Bender]

I didn't know about the reputation, but I agree with your position.

[KipIngram]

I've noticed at least some of this material that is referred to as "reactionless" in the popular media coverage but then when you actually read the underlying work that turns out not to be a claim made by the people involved. So it sort of depends on what you're looking at. I didn't see any physics violations in the one I read, but it was absurdly impractical. Like milli Newtons of force for thousands of watts of power invested. The only application I could ever see it having even a chance at would be satellite station-keeping. I've got a buddy online who's just convinced it's "star drive here we come," but... no.

[imatfaal]

I've noticed at least some of this material that is referred to as "reactionless" in the popular media coverage but then when you actually read the underlying work that turns out not to be a claim made by the people involved. So it sort of depends on what you're looking at. I didn't see any physics violations in the one I read, but it was absurdly impractical. Like milli Newtons of force for thousands of watts of power invested. The only application I could ever see it having even a chance at would be satellite station-keeping. I've got a buddy online who's just convinced it's "star drive here we come," but... no.

 

They are reactionless - or at least claim to be. They have become wise to the fact that this requires them to explain how they are circumventing the conservation of momentum so they don't go on too much about this - frankly their explanations as to the theoretical reasons are balderdash.

 

Think about it this way - they claim that if you threw an imaginary sphere around the contraption in space that it would move forward with nothing leaving the imaginary sphere. That is to say that the system would undergo a net change in momentum with no external force; this breaches the conservation of momentum. Personally I think a decent amount of the thrust is of thermal origins (that is not reactionless), that some is due to magnetic interactions with support apparatus (that is external to system), and other things that have not been taken care of.

[Moontanman]

Thunderf00t says the EM drive will not work!

[KipIngram]

The explanation I read made specific mention of more photons leaving through one end than through the other end. Even though both ends were closed - I wondered if it was perhaps some kind of tunneling. But I don't really know enough about tunneling to do any kind of real evaluation.

 

Are there more than one of these concepts around? Because another thing I read made reference to somehow changing the mass of a vibrating plate (the weird crazy part was how they managed to do that). I remember that article striking me as totally absurd.

[imatfaal]

The explanation I read made specific mention of more photons leaving through one end than through the other end. Even though both ends were closed - I wondered if it was perhaps some kind of tunneling. But I don't really know enough about tunneling to do any kind of real evaluation.

 

Are there more than one of these concepts around? Because another thing I read made reference to somehow changing the mass of a vibrating plate (the weird crazy part was how they managed to do that). I remember that article striking me as totally absurd.

 

From my reading your first paragraph is very nearly what they claim - however they claim this all happens inside the vessel. The particles are created at one end - the "field"/"environment" causes these particles to change in momentum in their passage from one end to another thus transferring the momentum to the vessel. It all sounds like the claim that firing a gun within a shipping container in space will cause the container to move as the bullets strike the end wall - this neglects that the recoil is equal and opposite and will provide exactly the same force in the opposite direction; as we know the CoM will stay put. They get around this by claiming that the change in momentum is leveraged on some sort of zero-point energy field - this is where the magic is

[KipIngram]

Maybe I need to go back and find that and re-read it. On first reading I thought it seemed like stuff was leaving the two ends - just more through one end than the other. But it's been a while. And it definitely involved physics I'm only partially knowledgeable about. I'm really just an engineer. A PhD educated one, and I did try to load up on math and physics in graduate school, but I'm still not "professional grade" in those areas. Still in the "little learning" category of your signature quote (which I love, by the way).

[Moontanman]

From my reading your first paragraph is very nearly what they claim - however they claim this all happens inside the vessel. The particles are created at one end - the "field"/"environment" causes these particles to change in momentum in their passage from one end to another thus transferring the momentum to the vessel. It all sounds like the claim that firing a gun within a shipping container in space will cause the container to move as the bullets strike the end wall - this neglects that the recoil is equal and opposite and will provide exactly the same force in the opposite direction; as we know the CoM will stay put. They get around this by claiming that the change in momentum is leveraged on some sort of zero-point energy field - this is where the magic is

 

"You have to believe we are magic

Nothin' can stand in our way

You have to believe we are magic

Don't let your aim ever stray"

[imatfaal]

Maybe I need to go back and find that and re-read it. On first reading I thought it seemed like stuff was leaving the two ends - just more through one end than the other. But it's been a while. And it definitely involved physics I'm only partially knowledgeable about. I'm really just an engineer. A PhD educated one, and I did try to load up on math and physics in graduate school, but I'm still not "professional grade" in those areas. Still in the "little learning" category of your signature quote (which I love, by the way).

 

I think the problem with every explanation that I have seen from the experimenters is that it leaves far too much open and unsaid - which is probably why we come to such varying conclusions. And from your credentials I can assure you are far in advance of me

"You have to believe we are magic

Nothin' can stand in our way

You have to believe we are magic

Don't let your aim ever stray"

 

A bit of the divine Olivia Neutron-Bomb - perfectly fitting for a physics thread

[Bender]

It all sounds like the claim that firing a gun within a shipping container in space will cause the container to move as the bullets strike the end wall - this neglects that the recoil is equal and opposite and will provide exactly the same force in the opposite direction; as we know the CoM will stay put.

Allow me to nitpick : the force of bullet hitting the container is significantly larger than the force of the recoil (asuming sufficiently strong and stiff container), because it happens in a shorter time. It is the impulse that is equal and opposite.

 

Of course, the conclusion doesn't change.

Edited March 26, 2017 by Bender

[Delta1212]

Allow me to nitpick : the force of bullet hitting the container is significantly larger than the force of the recoil (asuming sufficiently strong and stiff container), because it happens in a shorter time. It is the impulse that is equal and opposite.

 

Of course, the conclusion doesn't change.

Don't you have that backwards?

[KipIngram]

Don't you have that backwards?

 

I took him to mean the force felt by the person shooting the gun (the force of the gun recoiling against the person's hand) vs. the force of the bullet striking the target. The recoil force would act over the entire time the bullet was accelerating down the barrel, and if that time was larger than the time taken for the bullet to stop in the block then he has it right - the recoil force would be lower.

 

(Recoil force)*(muzzle acceleration time) = Impulse = (striking force)*(deceleration time)

 

At least that what I read it to mean.

[Bender]

No, I don't have it backwards. Thank you KipIngram for clarifying.

Edited March 28, 2017 by Bender

[Delta1212]

Yes, you're right. Not sure what it was exactly that I was thinking when I read that now.

[Perpetuum Mobile]

 

another thing I read made reference to somehow changing the mass of a vibrating plate (the weird crazy part was how they managed to do that). I remember that article striking me as totally absurd.

 

 

Changing the mass of a vibrating plate ?!

 

It is impossible.

 

It is pseudo-science, hoax, magic, and witchcraft :