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This is an idea for a closed-system propulsion device using a

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Thread replies: 27
Thread images: 3

File: idea.png (76KB, 1810x1042px) Image search: [iqdb] [SauceNao] [Google]
idea.png
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This is an idea for a closed-system propulsion device using a theoretical EM-pulse-emitting antenna fixed inside a closed rectangular prism floating in space.

I AM NOT SUGGESTING THAT I THINK THIS WILL WORK.

However, I don't know enough about physics to know why it won't work. I am asking you guys why this won't do what the image shows:

>antenna emits a pulse of energy, system should not move because it causes an equal and opposite force on all sides of the antenna

>pulse hits the left side of the box, exerts force F1 on the left side of the box, and the whole system moves to the left

>later, pulse reaches the right side of the box and exerts force F2 on that side

>F1=F2 so the box stops moving

>box is now in a different place; another pulse can be emitted to continue in this direction
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>>7640499
I've been thinking something similar actually so i'll give you a bump for answers. Originally i was under the impression that sending this pulse of microwaves or whatever it has to be (some energy) wouldn't cause a force on the box, but if it does why wouldn't this work, along with the EM?
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File: emdrive.jpg (81KB, 1140x723px) Image search: [iqdb] [SauceNao] [Google]
emdrive.jpg
81KB, 1140x723px
it's already a thing senpai
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>>7640525
It would indeed impart a miniscule force. See solar sails.

>>7640530
I can understand why this device shouldn't work given current model of physics. Because the microwave energy is constantly emitted, the force on both sides of the device is constantly the same, if you consider the forces on the inside of the cone part pushing it back in the direction of the small end. My idea is different because the energy comes in one single pulse at a time, which will make the whole system move and then stop as it hits each wall
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>>7640499
From air analogies it obviously wouldn't work but judging by the EM Drive EM waves seem to be magic these days so who knows anon, give it a try, I'm curious.
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Nope. Because F1=F2, the box moves back to its origin. Your logic isn't entirely wrong, though. Just remove the top, right, and bottom walls and now you have a solar sail.
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>>7640559
Why? Think about it: After F1 happens, the box is moving to the left. F2 being equal stops the box from moving, it doesn't reverse it.
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>>7640499
That's just a photon rocket inside of a pointless box. Stupid.
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>>7640569
It's not, because a photon rocked emits the photons in a direction and they are sent away from the system. This thing recaptures the momentum of the photons within itself and the whole thing still moves.
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>>7640567
Oh you're right. Then it's just a handicapped solar sail. Look up the IKAROS space probe, solar sails work. Therefore, so does OP's tardbox.
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>>7640574
>This thing recaptures the momentum of the photons within itself and the whole thing still moves.
No. Think about it. You are saying that when the photon is emitted, nothing happens. That would mean that photon rockets don't work. What is actually happening is

1. You emit a photon. The box moves in the direction opposite to the direction of the photon.

2. The photon hits the other side of the box, stopping the box

So all you have is a photon rocket that stops itself pointlessly.
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>>7640583
right, it stops itself, but now it's in a different place than before. I agree that the idea would be more pointless to make than a photon rocket if it could be made, but that still doesn't address the problem of how this could work without actually emitting anything away from the system
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>>7640583
Oh, and it's not just a photon rocket aimed at the inside of a box. it's essentially two photon rockets pointed away from each other, mounted inside a box, and closer to one end than the other end. So when it emits the photons it doesn't move, when the left photon hits the left side it moves in that direction and when the right photon later hits the right side it stops moving, now at rest in a different place than before
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>>7640598
>but that still doesn't address the problem of how this could work without actually emitting anything away from the system
Huh? A bullet doesn't emit anything but will keep moving forever in a vacuum.

>>7640608
That's essentially the same thing as a photon rocket in a box...
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>>7640657
The bullet and gun "emit" from each other and both go off into space, away from each other, forever. A gun mounted inside a box that fired into its own inside wall would move backwards when fired, and stop when the bullet hits the wall, and its center of momentum would not have changed it just reordered its inside parts.
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>>7640678
Yes. And how do you think that is any different from the situation of the photon rocket in a box? Again, no momentum is being created. The photon and the box have a certain amount of momentum that does not change from the start.
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>>7640698
I was thinking the antenna doesn't lose mass when it emits the photon. But, you know, I guess it does
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>>7640547
But it does work man, they just proved it a few days ago
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File: EMisreal.png (28KB, 800x800px) Image search: [iqdb] [SauceNao] [Google]
EMisreal.png
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>>7640499
I see what you're trying to say OP, but consider the left side of pic related. The component forces of the light force on the top and bottom of the box would end up cancelling out the force on the left side of the box and it wouldn't move. If you designed the box in such a shape that the component opposing forces always "missed" the wall, it would work.
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>>7640782
I hope you're trolling
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>>7640798
What you guys fail to understand is that judging by the memedrive the logic you're using doesn't apply to EM waves. Before memedrive I'd have laughed at OP now I say hey why not give it a try
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disclaimer: i dont know much about EM

But are you retards forgetting about Newton's 3rd law? If an electromagnetic pulse creates a force one the box, wouldn't there be a force opposite to the pulse?

This seems like trying to use a fan attached to a sailboat to sail.

Also, why not just take off on end of the box?
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I just worked it out. Consider calculating the change in the center of mass of the system, using a loss in mass at the point of the emitter due to the photons (where the momentum p=mc, where m is the change in mass). Now, calculate the change in the center of mass due to the change in position of the body caused by the time delay of the photon momentum transfer on the two walls of the body.

If you do this correctly, you'll see that these changes in center of mass are equal in opposite; in other words, the center of mass remains in its original position. All that is happening is that you're shifting the position of the body relative to the center of mass of the entire system, so you'll never be able to get the body to move past the original center of mass.
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>>7640801
I hope you are too.
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>>7640937
1. No, I would think so, but don't know where it would be

2. Right but unlike with the sailboat, I don't understand why this won't work

3. that would work but i'm asking this for hypothetical purposes
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>>7640970
OP here, this guy got it. Actually seems pretty obvious, don't know why I didn't consider the loss of mass from the emitter. Thanks
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>>7640937
what many people in these threads don't realize is that EM--electrodynamics, specifically--is the go-to counterexample to Newton's Third law. It's been known for a very long time and is included in most mechanics books worth a damn that Newton's Third law is not really a physical law but holds for many forces/interactions. Simple contact forces analyzed in introductory mechanics will follow Newton's third law; however, for magnetic forces due to fields caused by moving charges, this is no longer true.
I haven't looked into the EM drive or the buzz behind it, but I can guarantee scientists who are analyzing it/testing it are fully aware of this. I think only clickb8 sites would even bring it up.
Thread posts: 27
Thread images: 3


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