Yes, this is a big question. I would assume that the size of the chamber correlates to the standing wave reflection of the EM emissions. If this is the case, building a larger device would most likely result in lower relative output. You could, maybe, try longer wavelength EM to better fit the larger chamber, but longer waves, IIUC, require more input to match the energy of shorter waves. On the other hand, if you tried running thousands of these things to get lots of output, your mass-to-thrust ratio would be fairly flat, I think. Looks like they have a ways to go to get to “70 days to Mars” or Biff’s hoverboard.
Thanks - I missed that post somehow. But I’m still trying to remember where I came across it. Might have been something Andrew Chaikin wrote - will come back when I find it.
One thing worth noting is that the tests described in the paper only went up to 80W, so the claim of 1.2mN/KW is not substantiated. It is only a projection. It seems likely that 1KW might cause problematic deformations in the device due to excessive thermal expansion. Making more powerful Q-drives will almost certainly be challenging.
That’s right - in fact if you put the table on frictionless castors, you would see the block move a bit, and the table recoil a bit - the centre of mass of the system would be unchanged.
Without the castors, the reaction force exerted on the table is transmitted into the ground - the reaction is still real, but the ground is big enough to make it impossible to measure.
It’s no different to me pushing the block across the table with my finger - my feet push against the floor - the block moves in one direction - the other part of the system (the earth and me) moves in the opposite direction, imperceptibly.
Right, but remember the old f=ma: every Q-drive unit itself adds mass to the vehicle. If you can generate 1 mN of thrust for each one, that is a force that gives you 1 m/s[sup]2[/sup] of acceleration per gram of driven mass. I suspect the device, as tested, weighs more than a gram.
What do you mean by energy? “Directional heat emission” would be sending out energy, and wouldn’t violate conservation of momentum. Any other photon emission would be sending out energy and wouldn’t violate conservation of momentum. The entire point of this drive is that the thrust is supposed to notcomefromemission of anything.
1.2mN/kW is a ratio. That they put in 80W and not 1kW is not relevant to the validity of that number, which quite obviously refers to the output of that specific device.
In fact, from the paper, it sounded like heat radiation may have been more concentrated forward, if it was not more or less isotropic.
It is a ratio based on what they measured at 80W. It is not established that the device would function with a 1KW input. It might well overheat to the point of failure. In your backyard, it would probably work, but in space, shedding excess heat tends to be much more difficult.
Yes, but you didn’t write “it might not scale” you wrote “the claim of 1.2mN/KW is not substantiated”. Which was wrong, it’s a ratio, it implies nothing about input.
Yeah, I think it will probably be hard to get anything useful or effective - I guess I was thinking there might be a way to design these things to be useful as structure in their own right, with the added benefit of being tiny engines.
Or maybe if they could be miniaturised to MEMS scale and built onto a solar panel - which then becomes a thrust panel.
There are a lot of valid reasons why one would want to test one of these things in space. For one thing, it makes it a heck of a lot easier to isolate the device away from other potential sources of force. For another, letting it run for a significant time without any other forces on it would make it a lot easier to see any effect. Just putting it in a drop pit or the Vomit Comet wouldn’t be good enough, because you can’t run the experiment for a long enough time in those.
And for this reason, if it isn’t debunked first on Earth, NASA will surely eventually launch one of these things. But that “if it isn’t debunked first” is key: There are still a heck of a lot of tests that can be performed here on Earth, a lot more cheaply than launching one. There’s no point paying for a launch until you’ve done all the cheaper things first.
Personally, my gut instinct is that it’s interacting in some way with the magnetic field of the Earth (in which case, it might even still work in orbit, though not in interplanetary space). But I’m not an experimentalist, and I haven’t studied this in any sort of real detail, so don’t give too much credence to my gut.
Is this the drive that was being described in the popular press as a “warp drive”? I’m guessing this is an exaggeration, but is there any credible way it can be described as such?
No, what you’re referring to is something entirely different, the Alcubierre Drive.
There are a few experiments to investigate fundamental principles related to this idea, but the drive itself is no more than highly speculative theory at this point. https://en.wikipedia.org/wiki/Warp-field_experiments