Quantum drive to orbit

[totalitor]

On June they will try quantum drive in space. Scam or not. What do you think?

 

https://www.universetoday.com/160516/the-first-all-electrical-thruster-the-ivo-quantum-drive-is-headed-to-space/

[StrandedonEarth]

First I’ve heard of it. All of these propellant-less drives rely on theoretical physics neither proven nor disproven. The fact that this system has gotten to the point of in-space testing is promising. It’ll be revolutionary if it works, but I won’t be surprised if it doesn’t work at all. Or if it does work, gets quietly buried in a top secret govt vault…

Edited March 22, 2023 by StrandedonEarth

[magnemoe]

Skeptical, as stated in the article the problem with an reaction-less engine is that it can easy be turned into an perpetual mobile, add one on each end of an long rotating bar in vacuum. 
Acceleration and power use will be constant while the energy stored will increase exponential, at some point you can link this up to an generator at the axle and draw out power while powering the engines. 
This does not require an mega structure, as I understood for the EM-drive, its not something who would be very hard to build but you wanted something like the largest vacuum chambers. 
And I don't believe in  perpetual mobiles. Now if its something who limit it, things looks a bit better. Everything from cars to bullets to particles in particle accelerators get harder and harder to accelerate as they go faster as energy is M*V^2. Take an electrical car, ignore air resistance and assume engine and drive train is perfect and it has 300 hp, at the start it would accelerate hard, but this will slow down as going from 50 to 100 km/h takes 3 times the energy than getting to 50 km/s, getting  from 100 to 150  km/h  take more energy than getting to 100. 

Rockets escapes this because they uses reaction mass, downside is that they are insanely less efficient than an car. 
 

[kerbiloid]

Spoiler

 

[sevenperforce]

F_T = v_e * m_e / t

Thrust = exhaust velocity times exhaust mass divided by time.

If exhaust mass is zero and thrust is nonzero then exhaust velocity is infinite, and that's impossible, because you can't exceed the speed of light.

If you're producing thrust, you're pushing against something. That's fundamental. It's the third law. For once, I would like to see one of these reactionless drive folks explain exactly what is being pushed against in a way that doesn't break physics.

And you can't just say "oh it pushes against virtual quantum particles" because if you're pushing against virtual quantum particles then the particles you push against stop being virtual and start being actual. And so you have a flow of mass. But virtual particles come in pairs, and so if the particles you push against stop being virtual and start being actual, their pairs also stop being virtual and start being physical, and you have an equal flow of mass in the opposite direction, and so you don't move.

If it's pushing against dark matter, then yes, we've got something. That could work, if you're stumbled upon a mechanism for dark matter interaction that no one else has thought of and that never manifests in nature. But dark matter is rather low density out here, so far from the galactic core, and so your math is going to have to take that into account and somehow come up with a match to your claimed acceleration.

Show the maths.

[Piscator]

Pointing out that this drive would violate the third law seems a bit besides the point when the whole thing is based on the assumption that it is actually only a guideline.

I think it highly unlikely that they're onto something, but it's at least nice to see their theory tested. No need to argue about it. Just let the universe be the umpire.

[K^2]

10 hours ago, StrandedonEarth said:

All of these propellant-less drives rely on theoretical physics neither proven nor disproven.

I mean, they're not disproven the same way tooth faeries aren't disproven.

4 hours ago, Piscator said:

Pointing out that this drive would violate the third law seems a bit besides the point when the whole thing is based on the assumption that it is actually only a guideline.

It's not, though. It's a mathematical consequence of the underlying symmetries of space-time. And if these symmetries weren't there, absolutely all of the general relativity and quantum field theory would be wrong. This is something that's backed up by every critical experiment we've been able to perform, some to ludicrous precision. For there to be anisotropies of space-time so far undetected, the effect would have to be on the order of 10^-15 or less. If the effect existed at all, which as pointed above is about as valid as assuming you can ask faeries to push your rocket based on our current understanding of physics, it would have to be so weak as to be entirely useless. Attaching a flashlight to your spaceship and using recoil from the photons would literally be more efficient than any possible exhaust-free propulsion allowed by the limits on the statistics of the experiments we have performed. You "only" need 300MW of power for every 1N of thrust with a photon drive, after all. If something more efficient was possible without generating exhaust, we would have found obvious discrepancies in particle resonance frequencies and binary neutron star orbits. If the anisotropy was significant enough to be a viable violation of the 3rd law to any practically measurable degree, we would have known about it for decades and have a working theory of it, and not some snake oil venture capitalist bait.

This is 100% a scam. Just reading through the company's press releases, which mentions zero relevant physics is a perfect indicator of said fact.

[Superfluous J]

1 hour ago, K^2 said:

I mean, they're not disproven the same way tooth faeries aren't disproven.

While true, no one's spending millions of dollars to launch a tooth fairy discovery test into space.

[K^2]

1 hour ago, Superfluous J said:

While true, no one's spending millions of dollars to launch a tooth fairy discovery test into space.

To continue this analogy, imagine that you're investing a billion dollars into an expedition to a long lost temple. There's a lot of myth surrounding that temple, but you're also pretty sure that whatever you dig up in terms of real, material goods will be worth the investment, and the lead on the location of the temple is pretty solid. Then somebody approaches you and says, "You know, for a million more, we'll check if the tooth faery is also there," and before you can kick them out of your office, they pull out the pamphlets where they show a pretty good advertising spin tying the tooth faery to the temple and its legend. And at that point, what's another million for some free publicity from the buzz?

That's basically what this is. This whole thing exists because some people look at it, and say, "Well, they're putting millions into that, so there must be something to it," all the while this isn't a huge endeavor. It's a pile of store-bought sensors on a metal body with some magnets going up to measure noting but noise as a part of a ride-share with literal tons of legitimate scientific equipment working on real discoveries.

P.S. Also, if you call it a Quantum Tooth Faery Effect, I'm not convinced you wouldn't be able to raise a few millions to investigate it.

Edited March 23, 2023 by K^2

[kerbiloid]

Dinosaurs were invented to sell plastic toys.

[KSK]

2 hours ago, Superfluous J said:

While true, no one's spending millions of dollars to launch a tooth fairy discovery test into space.

People dumped millions into Theranos despite their due diligence folks coming back and telling them to stay the heck away because the technology  was never going to work.

Fear of missing out is a powerful force for generating stupid decisions. 

[Gargamel]

3 hours ago, K^2 said:

Quantum Tooth Faery Effect

QTFE drive mod for KSP2

[magnemoe]

9 hours ago, K^2 said:

I mean, they're not disproven the same way tooth faeries aren't disproven.

Depend, if you say tooth faeries always replace an tooth in a glass of water with an coin its easy to disprove.  If it can its harder to disprove. 

Now this reminds me of an kids show I once watched. One of the kids lost a milk tooth, put it in a glass of water and got an dollar. 
Couple of days later they found an box of hundreds of animal teeth in the basement of the school or somewhere, the obvious idea for them  would be to put them in an bucket of water and get hundreds of dollar. 
Did not see or remember the ending, probably their parent asking there they got all the teeth from  

[kerbiloid]

So, they robbed the faery tooth farm. To be continued. The faery always come for their property.

At least they didn't rob other pupils taking their milk teeth to sell like their own.

[magnemoe]

5 hours ago, kerbiloid said:

So, they robbed the faery tooth farm. To be continued. The faery always come for their property.

At least they didn't rob other pupils taking their milk teeth to sell like their own.

More correct they planned an get rich fast scheme,  the knew a tooth could be be converted to an dollar. They found a lots of teeth and thought they could convert its to lots of money for an kid. 
Yes they stole them from the school or other place but it was an dusty box in an pretty public place. 
 

[K^2]

11 hours ago, magnemoe said:

Depend, if you say tooth faeries always replace an tooth in a glass of water with an coin its easy to disprove.  If it can its harder to disprove.

Oh, I assume a lot of goalpost moving to be involved, certainly. I have a feeling the QD team will also be shifting theirs when the launch fails to demonstrate any amount of thrust distinguishable from an outgassing due to unequal heating of the craft. That's just how that game is played.

But despite my eyes having rolled back so far upon seeing yet another impossible propulsion method being excused with the word "quantum," that I was able to see my own thoughts, I don't really mind this kind of a stunt, because, like I said above, it's just another few million into a ride-share, which carries a bunch of legitimate equipment, and really, this money is funding the launch. So we're going to get something good out of this whole thing. Just won't be from that specific box of circuits. So if they can keep milking it, and keep effectively subsidizing research payloads, I'm ok with it.

[Nuke]

its all a matter of show me the thrust. with space launch costs coming down, its getting cheap enough to make a cubesat test article than it is to do more extensive labwork on the ground. and there are always idiots enthusiasts to scam crowdfund. whats a cubesat go for anyway? the price of an economy car? less post-starship.

Edited March 24, 2023 by Nuke

[K^2]

The funny thing is, you can generate thrust in orbit. There are so many different ways ranging in degree of practicality all having to do with the fact that you're not operating in a vacuum. The most obvious are solar sails, of course, but you can use any "imperfection" to push from. Magnetic tethers have been of much interest, since they can generate considerable thrust in Earth's magnetic field.

Most creative, of course, is noting that since you want to gain momentum, the symmetry you want broken is spatial, and if you have a gravity source, that symmetry is inherently broken already. The second clue is the spherical symmetry is there, so you'll have to live with the conservation of angular momentum^*, but unlike linear momentum, we know how to store it - just make the object spin. And that trivially leads to an obvious solution. Two satellites, a tether, and an electrically-driven winch. Start the two at slightly different elevation orbits. As the lower satellite starts to lead, winch it in, then, after they cross over, give the tether slack, and allow the two to separate again. With every swing, you'll be climbing to a higher and higher orbit, while the satellite pair starts gaining a counter-rotation matching perfectly the orbital angular momentum gain. Keep it up, and you can actually build up to the escape velocity^**, at which point you are ejected from the system, and you now have linear momentum. But that was always allowed, as you've used the entire planet as your propulsion mass.

But this doesn't have the word quantum in it, so people aren't interested. Maybe if I call it a "Gravity Drive", people will throw money at it, but I am, unfortunately, not good with fundraising in general.

 

^* Yes, Earth, and planetary bodies in general, are not perfect spheres. Their gravity has features, ranging from elongation due to rotation, to slight variations in the gravitational field due to elevation changes. You can, technically, use these to dump angular momentum as well, allowing a craft to escape the planet's pull using nothing but electricity and depart without any sort of rotation, but that will take a lot longer.

^** If your tether is long and strong enough. You will have to absorb a lot of angular momentum to escape. Of course, if you only need one of the two satellites to escape, that does open up additional possibilities...

[magnemoe]

5 hours ago, K^2 said:

The funny thing is, you can generate thrust in orbit. There are so many different ways ranging in degree of practicality all having to do with the fact that you're not operating in a vacuum. The most obvious are solar sails, of course, but you can use any "imperfection" to push from. Magnetic tethers have been of much interest, since they can generate considerable thrust in Earth's magnetic field.

Most creative, of course, is noting that since you want to gain momentum, the symmetry you want broken is spatial, and if you have a gravity source, that symmetry is inherently broken already. The second clue is the spherical symmetry is there, so you'll have to live with the conservation of angular momentum^*, but unlike linear momentum, we know how to store it - just make the object spin. And that trivially leads to an obvious solution. Two satellites, a tether, and an electrically-driven winch. Start the two at slightly different elevation orbits. As the lower satellite starts to lead, winch it in, then, after they cross over, give the tether slack, and allow the two to separate again. With every swing, you'll be climbing to a higher and higher orbit, while the satellite pair starts gaining a counter-rotation matching perfectly the orbital angular momentum gain. Keep it up, and you can actually build up to the escape velocity^**, at which point you are ejected from the system, and you now have linear momentum. But that was always allowed, as you've used the entire planet as your propulsion mass.

But this doesn't have the word quantum in it, so people aren't interested. Maybe if I call it a "Gravity Drive", people will throw money at it, but I am, unfortunately, not good with fundraising in general.

 

^* Yes, Earth, and planetary bodies in general, are not perfect spheres. Their gravity has features, ranging from elongation due to rotation, to slight variations in the gravitational field due to elevation changes. You can, technically, use these to dump angular momentum as well, allowing a craft to escape the planet's pull using nothing but electricity and depart without any sort of rotation, but that will take a lot longer.

^** If your tether is long and strong enough. You will have to absorb a lot of angular momentum to escape. Of course, if you only need one of the two satellites to escape, that does open up additional possibilities...

As I understand SpaceX uses the non spherical proberties of earth for inclination changes on their starlink satellites. 

[NFUN]

2 minutes ago, magnemoe said:

As I understand SpaceX uses the non spherical proberties of earth for inclination changes on their starlink satellites. 

https://en.m.wikipedia.org/wiki/Sun-synchronous_orbit

It's not an uncommon tool in general and it's well-known and understood

[K^2]

1 hour ago, magnemoe said:

As I understand SpaceX uses the non spherical proberties of earth for inclination changes on their starlink satellites. 

The underlying principle is the same, yeah. Though, if you are limited to treating a satellite as a rigid body, all you can really do in practice is move about the argument of the periapsis and the longitude of the ascending node. Great if you just need to spread satellites into a constellation or want your orbit to precess with a fixed speed, but it won't let you climb to a higher orbit or change eccentricity in a controlled way.