Accoustic Levitation (also emdrive ruminations)

[Nuke]

http://hackaday.com/2016/12/02/joled-a-3d-flip-dot-display/

this was pretty interesting, a physical voxel display that can move little balls around within a volume, using nothing more than an array of ultrasonic transducers. standing waves levitate the balls while their orientation is controlled with electrostatic fields and can operate as a flip dot display. rather impressive.

but then this got me thinking about em drive. i was thinking about the about the forces on the ball resisting the forces of gravity, if there is a force pushing the ball up, then should there not be a counter force as a result pushing the whole apparatus down? thats just basic physics, both ball and machine are pushing on each other and the momentum is conserved. of course take the ball away and all you're still moving little pockets of slightly denser air around. em drive doesnt try to levitate any balls (that would at least make the device look more interesting). makes one wonder if the microwaves in the em drive arent trapping little pockets of quantum soup between the nodes and so the drive could push off of those.

Edited December 3, 2016 by Nuke

[Jonfliesgoats]

Acoustic levitation is entirely possible with known laws of physics.  EM drive isn't.

[Scotius]

*evil smile* Then why it's working? And, preemptively - before someone answers with "It's just measurement error.": why no one was able to point out any errors and mistakes in experiments conducted so far, in several places, using different setups? No one so far pointed his finger and said: "You did this thing wrong, and that's why EMdrive is a dud."

[YNM]

Because if your theory is right, EM Drive is just spewing photons as it's reaction mass, which is also called a photon drive.

Which the thrust is, in any way, very, very light. Not going to hover anything unless a stupendous amount is spewed. And not going to fulfill the current figure.

 

That's why we want to test them in pure vacuum.

Edited December 3, 2016 by YNM

[Jonfliesgoats]

Good science requires an open mind.  This means we don't assume something can't work because of known physics, nor do we assume something does work based on preliminary observations.  We need more testing to figure out what is going on.  

My earlier statement simply means that there is less mystery around acoustic levitation than there is around the EM drive.

[Nuke]

i mostly liked the acoustic levitator because for once it allows you to visualize waves better. with that in mind i pictured the waves in a em drive resonance chamber, and replacing the ball with a soup of quantum particles. then if these particles interact with the wave but not the chamber itself, then what you got is a quantum wench. thought experiments are after all why we have e=mc^2. though there is little science in this line of though, i dont know enough about wave mechanics or the standard model to really define what quantum soup is or if any interaction would take place.

besides if em drive turns out to be a crock of beans, woodward drive still exists. and i dont know why it doesn't get nearly as much hype as em drive.

Edited December 4, 2016 by Nuke

[Darnok]

On 3.12.2016 at 8:41 AM, Jonfliesgoats said:

Acoustic levitation is entirely possible with known laws of physics.  EM drive isn't.

But we don't know all laws of physics and we are not 100% sure that those we know, we understand correctly.

[Jonfliesgoats]

Exactly, Darnok.  My assertion is not that the EM drive doesn't work, nor that to does.  I am saying we understand acoustic levitation.  We don't fully understand the observations made around the EM drive.  With acoustic levitation we see an engineering challenge.  With the EM drive, we see a research challenge.

There is a lot of pseudoscience for money and fame out there.  Look at the sham research that caused the anti-vaccination movement!  So a healthy dose of skepticism is a good thing.  Dismissing something out of hand, as is common with large groups of peers, is a bad thing.  The idea of plate tectonics was dismissed widely too.

I guess my point is we should all keep our emotions and excitement around unproven tech low until we know more.  Otherwise various bias works it's way into evaluation and employment of this tech.

There is an emotional component to airlift, a technological innovation of the mid 20th century.  The visuals o a C-47 or C-130 offloading food to starving kids are powerful.  Unfortunately, the actual, measurable effect of humanitarian airlift is negative.  Airlift, especially in the long term, hurts those in need!  That was a hard lesson for me, and I was very slow to accept it due to my emotion-based bias.

[Jonfliesgoats]

With regard to Mach Effect Thrusters, it seems that device is also unproven and cannot be reliably dumplicated by others. 

[Scotius]

28 minutes ago, Jonfliesgoats said:

There is an emotional component to airlift, a technological innovation of the mid 20th century.  The visuals o a C-47 or C-130 offloading food to starving kids are powerful.  Unfortunately, the actual, measurable effect of humanitarian airlift is negative.  Airlift, especially in the long term, hurts those in need!  That was a hard lesson for me, and I was very slow to accept it due to my emotion-based bias.

I always assumed airlift is a 'quick and dirty' solution to a sudden problem, before proper logistic channels can be established. It's understandable that airplanes can't ferry as much cargo as trains or freighter ships, and they are much less economical while doing so - but they can reach the crisis site in hours, not days and weeks after. It's not ideal, but it's better than nothing - especially when people are dying right now.

[YNM]

Yeah, when it all comes to quantum we can just silently assume everything happens

Probably I'm not really into quantum things and be the "old dinosaur".

But still, get them in space and see what happens dangit !

 

EDIT :
A bit of afterthought : If one can't devise the theory of why it works, why not devise the law ? Maybe X amount of power for a given size would result in Y amount of thrust ? Or X size of the chamber would result in Y amount of thrust, and so on ?

Edited December 4, 2016 by YNM

[Jonfliesgoats]

3 hours ago, Scotius said:

I always assumed airlift is a 'quick and dirty' solution to a sudden problem, before proper logistic channels can be established. It's understandable that airplanes can't ferry as much cargo as trains or freighter ships, and they are much less economical while doing so - but they can reach the crisis site in hours, not days and weeks after. It's not ideal, but it's better than nothing - especially when people are dying right now.

I don't want to hijack this thread and turn into one about airlift.  That said, short term airlift capabilities ARE valuable for responding to an emergency or disaster.  Over the course of days not weeks, the resources spent on airlift can be better spent elsewhere.  There is a whole discussion to be had about the infrastructure and security footprint of short and long term airlift compared to other efforts.  Worse, having regional airlift capability, say in a humanitarian organization, actually removes incentives for redundundant capabilities in low cost, ground infrastructure.

From an academic perspective, right and "wrong"application of airlift actually gets pretty interesting.

Maybe I should start a thread to debate the merits and lack thereof of airlift efforts?

[Nuke]

11 hours ago, Jonfliesgoats said:

With regard to Mach Effect Thrusters, it seems that device is also unproven and cannot be reliably dumplicated by others. 

i think in terms of per review its night and day. mach/woodward effect has been widely peer reviewed while shawyer's original paper had been flat out rejected. also the theories about why the woodward drive should work without breaking conservation laws has been around for a long time. with the em drive its "we dont know why this works".

Edited December 4, 2016 by Nuke

[Jonfliesgoats]

Hmm.  I need to learn more about the MET then.  Woodward's theory is certainly fascinating.