Author Topic: No Joke: NASA Working on Warp Drive  (Read 35898 times)

Offline cordwainer

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Re: No Joke: NASA Working on Warp Drive
« Reply #40 on: 06/15/2014 03:51 am »
I would also point out that saying quantum fluctuations are somehow fanciful in and of themselves would be tantamount to calling into question the Standard Model's understanding of the early universe, the Big Bang and inflationary theory. Quantum fluctuations are one of the many as yet unexplained phenomenon scientists use to explain the inexactness we currently see within the Standard Model. Hmm, sort of like dark matter, dark energy and a non-zero cosmological constant.

Offline 93143

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Re: No Joke: NASA Working on Warp Drive
« Reply #41 on: 06/15/2014 04:43 am »
I've not been following the Q-thruster stuff too closely - is there a plausible story yet about how it doesn't violate conservation of energy? (a question that any purported reactionless drive needs to be able to answer)

does it abide by the photon rocket limit?
I too would like to know this...
There must be some mechanism that limits the Q-thruster/Woodward drive vehicle so that the energy supplied in accelerating it is always greater than


Does anyone know what that mechanism is?

Short version:  just like with ordinary rockets, you have to take the reaction mass into account if you want to get a sensible answer.  An M-E thruster supposedly reacts against the rest of the mass in its lightcone via gravinertial radiation.  A Q-thruster supposedly reacts against transient particles created by quantum fluctuations; the particles may not persist, but the momentum has to go somewhere and presumably does...

If you only consider the kinetic energy of the thruster and vehicle, you can never solve the conservation equations consistently because a single-component kinetic energy is not Galilean-invariant (or Lorentz-invariant, if you insist on using relativity for your toy problems).  You're trying to analyze half of an open system and naturally enough getting garbage.
« Last Edit: 06/15/2014 08:29 am by 93143 »

Offline IslandPlaya

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Re: No Joke: NASA Working on Warp Drive
« Reply #42 on: 06/15/2014 01:39 pm »
Thanks for your comments. My stating 'Prove it's impossible' was misguided.
I guess I just want some form of propellant-less drive to be possible and my limited knowledge of physics led me to the most obvious objection to it. I hoped there must be an easy answer.
93143 hints at a solution to my naive analysis but doesn't really go into detail. I suspect because he too doesn't understand the 'toy' problem enough.
He states "An M-E thruster supposedly reacts against the rest of the mass in its lightcone via gravinertial radiation."
The mass in the thruster's lightcone once it is switched on? This is obvious nonsense. The lightcone of the thrusters particles since they were 'created'? That would include the entire (observable?) Universe then.
After doing some further reading the KE of the postulated vehicle is supposed to come from the mass-energy of the causally connected Universe... That's one hell of an open system, or is it a closed system?
I guess the jury is still out on this.
I await news of more research with interest.

Offline john smith 19

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Re: No Joke: NASA Working on Warp Drive
« Reply #43 on: 06/15/2014 02:39 pm »
Thanks for your comments. My stating 'Prove it's impossible' was misguided.
I guess I just want some form of propellant-less drive to be possible and my limited knowledge of physics led me to the most obvious objection to it. I hoped there must be an easy answer.
93143 hints at a solution to my naive analysis but doesn't really go into detail. I suspect because he too doesn't understand the 'toy' problem enough.
He states "An M-E thruster supposedly reacts against the rest of the mass in its lightcone via gravinertial radiation."
The mass in the thruster's lightcone once it is switched on? This is obvious nonsense.
Wrong.

http://en.wikipedia.org/wiki/Light_cone
Quote
The lightcone of the thrusters particles since they were 'created'? That would include the entire (observable?) Universe then.
After doing some further reading the KE of the postulated vehicle is supposed to come from the mass-energy of the causally connected Universe... That's one hell of an open system, or is it a closed system?
I guess the jury is still out on this.
I await news of more research with interest.
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline IslandPlaya

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Re: No Joke: NASA Working on Warp Drive
« Reply #44 on: 06/15/2014 02:44 pm »
How is it wrong? I understand what a lightcone is. Example: If I switch on a ME thruster on Earth, after 1/10 sec the Moon is not in the thrusters lightcone.

Offline momerathe

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Re: No Joke: NASA Working on Warp Drive
« Reply #45 on: 06/15/2014 05:40 pm »
[...] A Q-thruster supposedly reacts against transient particles created by quantum fluctuations; the particles may not persist, but the momentum has to go somewhere and presumably does...


That's why I asked if there's a "plausible story". This is not a plausible story, this is at the level of waggling your fingers an going 'oooh, magic!'

Quote
If you only consider the kinetic energy of the thruster and vehicle, you can never solve the conservation equations consistently because a single-component kinetic energy is not Galilean-invariant (or Lorentz-invariant, if you insist on using relativity for your toy problems).  You're trying to analyze half of an open system and naturally enough getting garbage.

you can certainly analyse the energetics of partial systems - in terms of inequalities. Unless the kinetic energy of the exhaust is negative? Or the device is extracting energy from the quantum vaccuum. Either of which would be rather significant discoveries.
thermodynamics will get you in the end

Offline SteveKelsey

Re: No Joke: NASA Working on Warp Drive
« Reply #46 on: 06/15/2014 10:10 pm »
After doing some further reading the KE of the postulated vehicle is supposed to come from the mass-energy of the causally connected Universe... That's one hell of an open system, or is it a closed system?

No. It's simply a closed system the size of the cosmos. There, I hope that helps. ;D
2001 is running a little late, but we are getting there.

Offline 93143

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Re: No Joke: NASA Working on Warp Drive
« Reply #47 on: 06/16/2014 12:47 am »
[...] A Q-thruster supposedly reacts against transient particles created by quantum fluctuations; the particles may not persist, but the momentum has to go somewhere and presumably does...


That's why I asked if there's a "plausible story". This is not a plausible story, this is at the level of waggling your fingers an going 'oooh, magic!'

I'm not claiming the Q-thruster works.  I'm claiming that if it works, it will conserve momentum by reacting against something, and thus any conservation argument that neglects the reaction mass is invalid.  Like the M-E thruster, it is not a "reactionless" drive; it doesn't claim to produce force out of nowhere.

Quote
Quote
If you only consider the kinetic energy of the thruster and vehicle, you can never solve the conservation equations consistently because a single-component kinetic energy is not Galilean-invariant (or Lorentz-invariant, if you insist on using relativity for your toy problems).  You're trying to analyze half of an open system and naturally enough getting garbage.

you can certainly analyse the energetics of partial systems - in terms of inequalities. Unless the kinetic energy of the exhaust is negative? Or the device is extracting energy from the quantum vaccuum. Either of which would be rather significant discoveries.

It's all about the frame of reference.

http://talk-polywell.org/bb/viewtopic.php?f=10&t=2215&start=1995#p105085

If the reaction mass is moving in the same direction as the thruster with respect to an observer, the kinetic energy of the "exhaust" can indeed be below its initial state.  This is how the Oberth effect works...

And yes, the whole point of the Q-thruster is that it exchanges momentum and energy with the quantum vacuum.  Just as the point of the M-E thruster is that it exchanges momentum and energy with all matter within its Hubble sphere (there; happy?).

Whether the proposed physical mechanism of each thruster makes sense is a separate question, but the fact remains that you cannot demonstrate anything either way by complaining about the kinetic energy of the spacecraft while ignoring the reaction mass.
« Last Edit: 06/16/2014 10:19 am by 93143 »

Offline KelvinZero

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Re: No Joke: NASA Working on Warp Drive
« Reply #48 on: 06/16/2014 09:31 am »
I too would like to know this...
There must be some mechanism that limits the Q-thruster/Woodward drive vehicle so that the energy supplied in accelerating it is always greater than


Does anyone know what that mechanism is?

If we are going to consider FTL and reactionless drives, we shouldn't be scared of a little free energy. :)

When I was talking about paradoxes before, My point wasn't that paradoxes mean it is not worth investigating. Its more that you just simply absolutely have to explore how paradoxes get resolved within whatever proposal, or you simply have no idea what you have. It would be the same as saying, "I have produced FTL, but I dont know how it behaves." The claim would not have any real meaning.

Offline francesco nicoli

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Re: No Joke: NASA Working on Warp Drive
« Reply #49 on: 06/16/2014 10:06 am »
just because Dr white was not satisfied with the sigma level of his data and analysis does not mean he reported negative results. he said quite the opposite. (that the preliminary results were suggestive that he had detected a warp and he was encouraged by them) that is... unless there was a report after the one i saw.

"Not satisfied with the sigma level" means statistical analysis of the data did not support the conclusion.  That's a negative result.  At least it's a negative result to real scientists.  White not reporting it doesn't mean the result wasn't negative.  A preliminary result is what you get when you are doing a preliminary test, not when you do a rigorous experiment and it doesn't give the results you like.

(Also, why is it that some parts of your post follow standard capitalization rules and some do not?  Do you not realize that standard capitalization lets people read more quickly?  By putting a little more effort into generating your content, you will be aiding the many people you are asking to read it by posting.)


not really. one thing is sample significance, the other is statistical significance. You can have positive results but statistically not significant- ie results are correct for the sample but cannot be generalized because you might have errors in sample selection. positive but statistically insignificant results do not imply that the study is to be thrown away: statistical significance can be improved by largerly increase the sample, so in this case the testbed experiments run.

Offline momerathe

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Re: No Joke: NASA Working on Warp Drive
« Reply #50 on: 06/16/2014 10:16 am »
I'm not claiming the Q-thruster works.  I'm claiming that if it works, it will conserve momentum by reacting against something, and thus any conservation argument that neglects the reaction mass is invalid.  Like the M-E thruster, it is not a "reactionless" drive; it doesn't claim to produce force out of nowhere.

[...]

And yes, the whole point of the Q-thruster is that it exchanges momentum and energy with the quantum vacuum.  Just as the point of the M-E thruster is that it exchanges momentum and energy with all matter within the Hubble sphere (there; happy?) of the thruster.

The M-E thruster is a good example, I think. That does have a "story" about its method of operation - there's meat on the bones, if you will: you can take a view on the plausibility of Gravinertial theory or Wheeler-Feynman absorber theory. You (or at least Woodward) can do sums with it.

I was hoping that the Q-thruster has something like that. If it extracts energy from the quantum vacuum, how does it do it? does this imply a state transition in the quantum vacuum (like a false vacuum)? what is the four-momentum of the exhaust? how do these quantities vary under a change of reference frame? (you can quite easily do this for an ordinary rocket and see the frame velocity dependence cancel out)

Unless there's a "story" that addresses these questions, you can't talk intelligibly about whether might work or not, there's simply insufficient data.

Quote
but the fact remains that you cannot demonstrate anything either way by complaining about the kinetic energy of the spacecraft while ignoring the reaction mass.

I disagree, obviously. I'll go into my thinking in more detail if you want, but I've got no skin in this game so I'm content to let it lie.
thermodynamics will get you in the end

Offline DMeader

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Re: No Joke: NASA Working on Warp Drive
« Reply #51 on: 06/16/2014 01:19 pm »
What annoys me most about ill-informed and misleading stories like the one that spawned this thread is than now the general media has picked up on it, and the general public is getting the idea that in a couple of years we'll be flying around in NASA's new warp ship.

Offline JohnFornaro

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Re: No Joke: NASA Working on Warp Drive
« Reply #52 on: 06/16/2014 01:27 pm »
http://rationalwiki.org/wiki/Statistical_significance

You may find the section on 'The problems with statistical significance' interesting reading

Thanks for the link to the oracle.

An abuse of statistics is when journalists or certain agenda pushers ignore the concept of significance entirely - leading to false information being given out to people.

Note that reciting a definition of "statistical abuse" is by no means an accusation of the practice of pseudoscience.

... it would mean more space and mass allowances for equipment and materials for use at the various destinations such a craft could get to right here in this solar system.

"Would" being the only operative term.  "Everybody" knows about the benefits of increasing the speed of the spacecraft.

Oh, it's the same old capacitors/reactionless shtick. Next thread!
Granted. It wont work if my inequality above us violated, but why not in general. Can you prove such a thing is impossible?

You know that "proving the impossible" is a fool's errand.

First, prove that your "inequality" is not violated by using the information provided by Mr. White.  There is no point in further discussion otherwise.

Mr Sonny White must know this... Whats going on?

Scientainment.

'Prove it's impossible' was misguided.

Good job.
Sometimes I just flat out don't get it.

Offline 93143

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Re: No Joke: NASA Working on Warp Drive
« Reply #53 on: 06/16/2014 09:34 pm »
Quote
but the fact remains that you cannot demonstrate anything either way by complaining about the kinetic energy of the spacecraft while ignoring the reaction mass.

I disagree, obviously. I'll go into my thinking in more detail if you want, but I've got no skin in this game so I'm content to let it lie.

It seems like we're more or less on the same page.  Could you elaborate on this?

Offline momerathe

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Re: No Joke: NASA Working on Warp Drive
« Reply #54 on: 06/17/2014 10:37 am »
It seems like we're more or less on the same page.  Could you elaborate on this?

Sure, here's what I'm thinking:

Let's consider the simple energy balance between energy in and energy out. For the moment I'll ignore spooky quantum effects, but I'll come back to them.

The only energy input into the system is electrical energy into the drive: (assumption 1)

Eelec ≥ ΔKEvehicle + ΔKEexhaust   (1)

This has to be true whatever frame you analyse it in.

ΔKEexhaust ≥ 0, because we're assuming that you have no effect on the exhaust plume previously emitted, and the KE of the extra exhaust during our time step is axiomatically positive (assumption 2)

(aside: why is this not true for rockets? because from a sufficiently boosted frame it looks like the vessel is decelerating its propellant. So, if you think in terms of the propellant, ΔKEpropellant can be negative. Here, however, the total mass of the vehicle does not change. People complain about "reactionless" drives, but the real problem is a "propellantless" one.)

given this, if we write:

Eelec ≥ ΔKEvehicle  (2)

we can see that if (2) is false, (1) must also be false. As ΔKEvehicle is frame-dependent and Eelec is not, you can always choose a frame where (2), and thus (1), is not true.



How can we get around this? let's consider our two assumptions.

break assumption 2: the "exhaust" has negative Kinetic Energy. I don't even know what this means ;). Negative exhaust mass maybe?

break assumption 1: there is some other energy input into the system. Presumably from the "quantum vacuum". The observed magnitude of this energy input will vary depending on the relative velocity of the observer, which is... odd. Reminds me weirdly of black hole complementarity, actually. If there's energy coming from the quantum vacuum, what does this imply about the energy levels of the vacua?


So there it is. I'd like an explanation of which of these assumptions is broken and how.

(edited for typos)
« Last Edit: 06/17/2014 01:35 pm by momerathe »
thermodynamics will get you in the end

Offline 93143

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Re: No Joke: NASA Working on Warp Drive
« Reply #55 on: 06/17/2014 07:57 pm »
ΔKEexhaust ≥ 0, because we're assuming that you have no effect on the exhaust plume previously emitted, and the KE of the extra exhaust during our time step is axiomatically positive (assumption 2)

I believe the problem lies with assumption 2.

Quote
(aside: why is this not true for rockets? because from a sufficiently boosted frame it looks like the vessel is decelerating its propellant. So, if you think in terms of the propellant, ΔKEpropellant can be negative. Here, however, the total mass of the vehicle does not change. People complain about "reactionless" drives, but the real problem is a "propellantless" one.)

The hidden assumption here seems to be that the reaction mass for a "propellantless" thruster is initially stationary with respect to the observer.

As a trivial counterexample, consider a 1500 kg car on the highway, moving at 30 m/s.  You (the observer) are in another car moving at 35 m/s in the other direction.  The first vehicle is accelerating at 0.5 m/s˛, exerting a 2000 N force on the road (60 kW, or ~80 hp) in order to do so (yes, this includes air resistance).  As a result of this, from your perspective its kinetic energy increases at 48.75 kW, while the kinetic energy of the Earth decreases at 70 kW.

If I had done this example without air resistance, the first car would have been gaining more kinetic energy than it expended in shaft work.  In fact, in this example the air resistance alone soaks up more energy than the car expends in shaft work...

It's not the fact that a rocket expends propellant that makes the Oberth effect work; it's the fact that the propellant is initially moving at the same velocity as the rocket.

...

It seems to me that if a given space drive obeys Lorentz covariance, as M-E seems to and as the Q-thruster had better if it's going to have a shot at being physically plausible, the effective mean velocity of the propellant should be tied to the velocity of the thruster, not that of the observer.  At worst, it would be tied to neither, which seems more plausible with M-E than with the Q-thruster (except that the M-E equation doesn't show any dependence on the mean velocity of the distant matter; indeed it doesn't directly reference the distant matter at all).

I'm not familiar enough with quantum mechanics to say much about the Q-thruster, but in the case of M-E it isn't obvious how such a coupling would work.  Still, while preferential interaction based directly on the velocity of the distant matter in question doesn't seem to make sense, I suspect that the peculiar velocity of the thruster (velocity minus comoving velocity) could result in a preferential direction of interaction, which in an expanding universe is effectively the same thing...

Do not quote me on this as I have not done the math...
« Last Edit: 06/17/2014 08:02 pm by 93143 »

Offline IslandPlaya

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Re: No Joke: NASA Working on Warp Drive
« Reply #56 on: 06/17/2014 08:36 pm »
It seems reasonable that the reaction mass for a "propellantless" thruster is in an inertial reference frame. So yes, it is stationary with respect to the observer. If this were not the case then you would run into all sorts of trouble with Special Relativity.
So the hidden assumption is in fact true IMHO.

Offline momerathe

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Re: No Joke: NASA Working on Warp Drive
« Reply #57 on: 06/17/2014 10:35 pm »
The hidden assumption here seems to be that the reaction mass for a "propellantless" thruster is initially stationary with respect to the observer.

kinda - I'm assuming the reaction mass is being magically handwaved into existence :)
In fairness, that's what descriptions of the device sound like..

Like I said, there's something going on - I'd just like a hypothesis as to what that something is.
thermodynamics will get you in the end

Offline 93143

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Re: No Joke: NASA Working on Warp Drive
« Reply #58 on: 06/17/2014 11:50 pm »
Well, that's no good...

Why are we so concerned about conservation of momentum and energy if conservation of mass isn't being respected?

It seems (from the references on Wikipedia) that White is trying to leverage the dynamic Casimir effect or something like that, and he asserts that there will be a "wake" of some sort.  This is not something out of nothing; it is at most a zero-point energy device.  And I would imagine that if the principle of operation turns out to be physically consistent, the phenomenon will be linked to the thruster's frame of reference due to Lorentz covariance - how it sees the vacuum shouldn't depend on its velocity as seen by an observer.

So the question isn't so much "how does the Q-thruster conserve energy?" as "how does the Q-thruster work?".  If you can answer that, it should become evident whether or not it has conservation issues.  If you can't answer that, you have no basis for bringing in stuff like assumption 2.

@IslandPlaya:  Just because something's in an inertial reference frame doesn't mean it's in your inertial reference frame.  Take a look at my example with the cars.
« Last Edit: 06/18/2014 12:03 am by 93143 »

Offline momerathe

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Re: No Joke: NASA Working on Warp Drive
« Reply #59 on: 06/18/2014 01:06 pm »
Well, that's no good...

Hey, it's not my job to explain it, merely to show that an explanation is required :D

Quote
Why are we so concerned about conservation of momentum and energy if conservation of mass isn't being respected?

mass is not a conserved quantity.

Sure, I could have added the mass-energy of the exhaust to the right hand side of the inequality, but as that is also axiomatically positive (even for hypothetical particles of negative mass) nothing changes. Besides, it's not clear to me that the device is creating real (i.e. mass-shell) particles, so saying they have mass is the assumption, not the other way round.


Quote
It seems (from the references on Wikipedia) that White is trying to leverage the dynamic Casimir effect or something like that, and he asserts that there will be a "wake" of some sort.  This is not something out of nothing; it is at most a zero-point energy device.

When I'll have time I'll have to follow up on these references, because that sounds like word salad to me. The phrase "at most a zero-point energy device" is also rather eyebrow-raising, given that - according to our current understanding - such a thing is physically impossible. (That was my "assumption 1"). The significance of a zero point energy device would knock a poxy rocket engine into a cocked hat!

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So the question isn't so much "how does the Q-thruster conserve energy?" as "how does the Q-thruster work?".

As a physicist, those questions are one and the same.

Quote
If you can't answer that, you have no basis for bringing in stuff like assumption 2.

Once again, it's not my job to explain it, merely to show that an explanation is required.

Still, I think the "assumption" that the kinetic energy of a moving object is positive is a pretty well grounded one!

Quote
@IslandPlaya:  Just because something's in an inertial reference frame doesn't mean it's in your inertial reference frame.  Take a look at my example with the cars.

Actually, I think you're both right. I think the "initial velocity of the quantum vacuum" (and I put the phrase in quotes because I'm not even convinced it's meaningful) has to be zero in every inertial frame, otherwise you can say goodbye to the Principle of Relativity. This means that a stationary observer and an observer on the vehicle will "disagree", but that's not necessarily a problem.
« Last Edit: 06/18/2014 01:11 pm by momerathe »
thermodynamics will get you in the end

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