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Uncertain Propulsion Breakthroughs?

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Re: Uncertain Propulsion Breakthroughs?

#21

Post by StavrosK »

jdoliner wrote: post #16
Others wrote: post #5

Earlier quoted context omitted.

I don't think that's a fair summary... The author provides a more nuanced view than just "there is no effect." You're nitpicking from one section about theory, without considering the article as a whole. This is especially egregious considering that the article spends so much time talking about confirmation bias.

It even says explicitly: > Do you want to know our conclusions without any regard to how we reached those conclusions? ... If you answered “yes” to any of those questions, then you, like me, have natural human cognitive dysfunctions.

I don't understand that. Since I can't educate myself on everything required to make an informed decision on whether the paper is true or not, I decide to just trust someone else's opinion. I pick people to trust based on various criteria (how well they've cited their sources, how much other trustworthy people trust them, etc) and then just blindly believe whatever they say.

What else can I do?

Re: Uncertain Propulsion Breakthroughs?

#22

Post by Trombone12 »

The Summary: "this most recent report is a significant improvement, but has many shortcomings. Questionable subjective techniques are used to infer the “thrust” from the data. Other likely influences are not quantified. But also, despite those inadequacies, the possibility of a new force-producing effect cannot be irrefutably ruled out. This is intriguing, but still falling short of defensible evidence."

Re: Uncertain Propulsion Breakthroughs?

#23

Post by greglindahl »

xupybd wrote: post #14

Wow, I've not read something like that in a long time. More news needs to be like this. Examining what we know presenting where we are. Not taking sides and polarizing the discussion. I do think people miss one small aspect of this story. How long has it been since we've had a device built that we've no understanding of the principles of it's operation? I think that's an amazing fluke and (if the effect is genuine) s…

It is not unusual for a physics experiment to produce a weird result, and it turns out to be experimental error.

Re: Uncertain Propulsion Breakthroughs?

#24

Post by sandworm101 »

JumpCrisscross wrote: post #10
cperciva wrote: post #8

Earlier quoted context omitted.

Being in space doesn't solve the problem of errant forces completely. You can push against the earth's magnetic field, for example.

Satellite orbits degrade overtime due to drag, among other things [1]. Operators counter this decay with periodic boosts. (The International Space Station is boosted, on average, once a month [2].) Boosting, even electric propulsion boosting, consumes propellant. If this works by impelling against the Earth's magnetic field, provided it is more efficient than a simple magnet, it could still have a market with satelli…

For the power required to generate minimal thrust, this will not be useful in low orbit. The solar panels required to power the drive would result in more drag than the truster might overcome. So no market. And this test flight will not result in a clearcut "it stays up" rather "it fell slower than expected". There will be much calculation and debate re drag, magnetics and gravitational anomolies, so small are the expected forces.

To get a clear result we need something out closer to geostationary, flying for months well away from the earth's irregularities.

Re: Uncertain Propulsion Breakthroughs?

#25

Post by xupybd »

greglindahl wrote: post #23
xupybd wrote: post #14

Wow, I've not read something like that in a long time. More news needs to be like this. Examining what we know presenting where we are. Not taking sides and polarizing the discussion. I do think people miss one small aspect of this story. How long has it been since we've had a device built that we've no understanding of the principles of it's operation? I think that's an amazing fluke and (if the effect is genuine) s…

It is not unusual for a physics experiment to produce a weird result, and it turns out to be experimental error.

Yeah there is a very good chance that's still the case here. But would be cool if it's not experimental error.

Re: Uncertain Propulsion Breakthroughs?

#26

Post by xupybd »

alasdair_ wrote: post #18
xupybd wrote: post #14

Wow, I've not read something like that in a long time. More news needs to be like this. Examining what we know presenting where we are. Not taking sides and polarizing the discussion. I do think people miss one small aspect of this story. How long has it been since we've had a device built that we've no understanding of the principles of it's operation? I think that's an amazing fluke and (if the effect is genuine) s…

Quite a few medicines (especially antidepressants) state something like "we don't really know why this stuff works, only that it does."

Very true. I'd not considered the medical world.

Re: Uncertain Propulsion Breakthroughs?

#27

Post by Animats »

xupybd wrote: post #14

Wow, I've not read something like that in a long time. More news needs to be like this. Examining what we know presenting where we are. Not taking sides and polarizing the discussion. I do think people miss one small aspect of this story. How long has it been since we've had a device built that we've no understanding of the principles of it's operation? I think that's an amazing fluke and (if the effect is genuine) s…

There are others. There's cold fusion. There's a strange effect by which a rotating superconductor appears to induce gravity.[1] (Whatever happened to that? Articles from 2002-2006, then nothing.) They're all down near the noise threshold.

[1] https://www.sciencedaily.com/releases/2006/03/060325232140.h...

Re: Uncertain Propulsion Breakthroughs?

#28

Post by mquander »

StavrosK wrote: post #21
jdoliner wrote: post #16

Earlier quoted context omitted.

It even says explicitly: > Do you want to know our conclusions without any regard to how we reached those conclusions? ... If you answered “yes” to any of those questions, then you, like me, have natural human cognitive dysfunctions.

I don't understand that. Since I can't educate myself on everything required to make an informed decision on whether the paper is true or not, I decide to just trust someone else's opinion. I pick people to trust based on various criteria (how well they've cited their sources, how much other trustworthy people trust them, etc) and then just blindly believe whatever they say. What else can I do?

> how well they've cited their sources, how much other trustworthy people trust them, etc

That sounds to me like a "regard to how they reached those conclusions" (maybe a regard to how they reached a subset of their conclusions, and extrapolating to the rest). It's not the most regard you could possibly have, but it's lots.

Re: Uncertain Propulsion Breakthroughs?

#29

Post by JumpCrisscross »

sandworm101 wrote: post #24
JumpCrisscross wrote: post #10

Earlier quoted context omitted.

Satellite orbits degrade overtime due to drag, among other things [1]. Operators counter this decay with periodic boosts. (The International Space Station is boosted, on average, once a month [2].) Boosting, even electric propulsion boosting, consumes propellant. If this works by impelling against the Earth's magnetic field, provided it is more efficient than a simple magnet, it could still have a market with satelli…

For the power required to generate minimal thrust, this will not be useful in low orbit. The solar panels required to power the drive would result in more drag than the truster might overcome. So no market. And this test flight will not result in a clearcut "it stays up" rather "it fell slower than expected". There will be much calculation and debate re drag, magnetics and gravitational anomolies, so small are the ex…

> For the power required to generate minimal thrust, this will not be useful in low orbit

A recent paper [1] quotes this system's predicted efficiency at 1.2 mN/kW. Hall thrusters, a propellant-throwing electric engine, perform at 60 mN/kW. Non-propellant systems like light sails, laser propulsion and photon rockets perform around 0.0033 to 0.0067 mN/kW.

If this works, and that's a big if, a 50x performance improvement over the prototype is not unrealistic.

[1] https://regmedia.co.uk/2016/11/09/q_thruster.pdf

Re: Uncertain Propulsion Breakthroughs?

#30

Post by dom0 »

JumpCrisscross wrote: post #10
cperciva wrote: post #8

Earlier quoted context omitted.

Being in space doesn't solve the problem of errant forces completely. You can push against the earth's magnetic field, for example.

Satellite orbits degrade overtime due to drag, among other things [1]. Operators counter this decay with periodic boosts. (The International Space Station is boosted, on average, once a month [2].) Boosting, even electric propulsion boosting, consumes propellant. If this works by impelling against the Earth's magnetic field, provided it is more efficient than a simple magnet, it could still have a market with satelli…

> If this works by impelling against the Earth's magnetic field

That's a completely different premise than the em-drive has, though. It's supposed to not depend on an external field; developing a force between two magnets wouldn't exactly qualify as (non-)rocket science today.

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