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Questions about Nasa's space drive answered

wired.co.uk

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Re: Questions about Nasa's space drive answered

#181

Post by idlewords »

readerrrr wrote: post #124
idlewords wrote: post #106

Earlier quoted context omitted.

Are you trying to suggest here that Baez isn't aware of the existence of virtual particles? He's done lots of work in quantum field theory.

He dismissed the idea in a very arrogant way, just look at the wording, because someone used a incompatible word. Yet, the experiments gave a result; but he doesn't like that, and instead of using arguments he used ridicule, which doesn't show any credibility.

If you find his tone objectionable, try to look past it. Baez is a fellow worth listening to. He makes a number of substantive arguments why this looks and smells like crank science (for example, the contradictory statements about whether the experiment was done in a vacuum). It's perfectly legitimate of him to point out some social cues that you would not expect from a serious scientist making this kind of claim.

The faster-than-light neutrino experiment gave a result, too, but in these cases the onus is massively on the people making the wild claims, and rightly so.

Re: Questions about Nasa's space drive answered

#182

Post by XorNot »

gilgoomesh wrote: post #98
gus_massa wrote: post #80

Short version: Unless they believe the machine breaks some of the fundamental physics laws, the device must emit something. With this definition using a red LED Laser powered by a 1.5V battery in the back of the spacecraft is a "no reaction mass" thruster. The problem is that the momentum / energy ratio has theoretical limitations, and they are getting too much momentum. Long version (based on a previous comment http…

NASA suspects the thrust comes from "quantum vacuum virtual particles". These literally come from nowhere and would be the balance in the conservation of momentum. See Casimir Effect or Hawking radiation for examples where quantum vacuum virtual particles have an effect.

Both of those conserve momentum. Black holes receive the momentum from their Hawking radiation (but in normal space are generally spherical - it's been proposed a 1000kg black hole might be able to be balanced and fed in a reaction chamber to give thrust), and the Casimir effect conserves momentum because it acts equally on the conductive plates but in opposite directions.

The problem here is where are they getting the thrust from and what mechanism is causing virtual particles to become real? And where in the energy for that coming from? Because you're paying not just KE but also the rest energy cost to make them real with Hawking radiation.

Re: Questions about Nasa's space drive answered

#183

Post by gus_massa »

Gravityloss wrote: post #152
ghshephard wrote: post #146

Earlier quoted context omitted.

I"m not following why you think the wheel generator will produce more power than is required to spin the wheel in the first place. Friction is a pretty big issue in your scenario. It seems orthogonal to the actual results.

The whole thing was a thought experiment to show how extraordinary the supposed result is. Power of the wheel = thrust * rim velocity. That's just basic physics you should learn in high school. P_1 = F * v This means if your force, that is, thrust, is constant, you generate more power the faster you go. That's also why cars accelerate faster from 20 to 30 km/h than from 120 to 130 km/h - they have constant power whic…

I totally misinterpret your first comment. It looks like "This is even more amazing! We have a perpetual mobile machine!!" but it's really is "This also break the energy conservation law! So we have a serious problem."

In special relativity, momentum and energy are much related, so if you break the conservation of one of them, you break also the conservation of the other. (It's not very clear if the authors say that this device break the momentum conservation, all the information is very confusing.)

But the example is nice. Just get two of these devices and put them in the opposite sides of a carrousel or a spinning space station so you don't have to worry about friction.

Re: Questions about Nasa's space drive answered

#184

Post by Gravityloss »

gus_massa wrote: post #183
Gravityloss wrote: post #152

Earlier quoted context omitted.

The whole thing was a thought experiment to show how extraordinary the supposed result is. Power of the wheel = thrust * rim velocity. That's just basic physics you should learn in high school. P_1 = F * v This means if your force, that is, thrust, is constant, you generate more power the faster you go. That's also why cars accelerate faster from 20 to 30 km/h than from 120 to 130 km/h - they have constant power whic…

I totally misinterpret your first comment. It looks like "This is even more amazing! We have a perpetual mobile machine!!" but it's really is "This also break the energy conservation law! So we have a serious problem." In special relativity, momentum and energy are much related, so if you break the conservation of one of them, you break also the conservation of the other. (It's not very clear if the authors say that…

Thanks for the comment, now I realize the post was not very well written in that regard. It is hard to express these contradicting ideas in a small space:

1. If this works, forget spacecraft. Free energy for everyone! 2. I think it's a measurement error.

There are other reasons to think so as well, a person said that the "out there" advanced space propulsion research community traditionally gives a lot more leeway than some other research disciplines where this might have come up.

Re: Questions about Nasa's space drive answered

#185

Post by DanBC »

tobinfricke wrote: post #127
bane wrote: post #116

Earlier quoted context omitted.

One of the problems with this idea, that we have the physics "perfectly understood", is that even that statement isn't accurate. What we actually have are unbelievably precise models for how things work and people who understand those models at extremely deep levels. But even something we experience literally every moment of every day, like gravity or magnets, we haven't the foggiest idea of how it actually works. We…

All models are wrong. Some are useful. But what is your point, really? By "understand" in physics, we really mean that we can predict what will happen in a given experiment to any desired accuracy based on the established "laws of physics". " But even something we experience literally every moment of every day, like gravity or magnets, we haven't the foggiest idea of how it actually works. " I think this does a deep…

> I think this does a deep disservice to how much we actually do know about how the universe works.

No! It just means that we know vast amounts about the Universe, but we still have more to learn.

Re: Questions about Nasa's space drive answered

#186

Post by shoyer »

forgotketchup wrote: post #160
mnl wrote: post #120

Earlier quoted context omitted.

I'd never understand how intelligent and educated people lose it completely when it comes to Physics. They've been exposed to some PopSci tales not meant to be accurate at all and then feel entitled to be right when they figure out some nonsensical consequences by themselves -no proper maths involved ever-. It's depressing. Baez is right, of course. I've been checking the (Word-generated) "papers" from this guy's gro…

> I've been checking the (Word-generated) "papers" from this guy's group at NASA, they're extremely shoddy. Not defending this particular paper, but I'm curious why you highlighted the fact that it's written in Word. Just about everybody in physics these days uses Word to compose papers (Word + Mendeley is a dream, by the way). Maybe you think he's not a 'real man' because he doesn't sling raw LaTeX?

"everybody in physics these days uses Word to compose papers"

What subfield of physics have you worked in?

In my experience, this is not remotely true. Almost paper I read in grad school (e.g., on arXiv/quant-ph) was written in LaTeX. The exceptions written in Word were indeed quite likely to be the work of crackpots...

Re: Questions about Nasa's space drive answered

#187

Post by MiguelHudnandez »

chopin wrote: post #168
MiguelHudnandez wrote: post #150

Earlier quoted context omitted.

> And because it does not require energy just to hold things up (just as a chair does not require power to keep you off the ground), in theory you could have a hoverboard which does not require energy to float in the air. An item where you could dump electricity into it once, cut power, and have it resist gravity -- forever, and for free! -- is absolute horse shit.

Any superconductor levitating on a magnet does exactly this. Afaik there is no law in physics we know of which forbids this. To put it even further: every stone lying on the ground does exactly this. It doesn't change its position relative to the gavitational field. And without expending any energy for that (or increasing the systems entropy ot hold its position). And this comes ultimately down to electromagnetic for…

A stone resting on the ground is simply halted at the place where gravity is overpowered by the repulsion between molecules. Both of those forces are applied constantly, and seemingly for "free." But those forces are inherent to all matter.

Two magnetic objects can resist each other, but that is well understood already. And still, those reach equilibrium between gravity (from the levitator) and the strong force (from the support structure). From the way I understand superconductive magnetic levitation, the magnetic field collapses the superconductivity in the places they intersect. That would mean that over time, electrical resistance would drain the [mostly] superconductive material.

Right now, all examples of superconductive levitation involve supercooled superconductors, which means that any examples require massive amounts of energy to sustain.

This hoverboard idea would be like taking the magnetic base away and expecting the levitator to remain where it is with no extra energy supplied.

We've gone from "we can turn energy into motive force through unknown methods" to "we can prime this thing with energy once and have it exert force forever." If that were true, you could dump 1kw into the thing, rotate it 90 degrees and attach it to a rotor. Now you've got this thing that constantly pushes your rotor around and you've got free energy forever. See how I might think we're in crazy town now?

Re: Questions about Nasa's space drive answered

#188

Post by TTPrograms »

readerrrr wrote: post #124
idlewords wrote: post #106

Earlier quoted context omitted.

Are you trying to suggest here that Baez isn't aware of the existence of virtual particles? He's done lots of work in quantum field theory.

He dismissed the idea in a very arrogant way, just look at the wording, because someone used a incompatible word. Yet, the experiments gave a result; but he doesn't like that, and instead of using arguments he used ridicule, which doesn't show any credibility.

The wording used indicates that the writers have no understanding of the current state of the field, which is extremely highly correlated with crackpottery in physics. It's not a comment on the experiment, it's a comment on the fact that the hand-wavy theoretical explanation doesn't pass the sniff test to anyone who's taken QFT.

Re: Questions about Nasa's space drive answered

#189

Post by TTPrograms »

forgotketchup wrote: post #160
mnl wrote: post #120

Earlier quoted context omitted.

I'd never understand how intelligent and educated people lose it completely when it comes to Physics. They've been exposed to some PopSci tales not meant to be accurate at all and then feel entitled to be right when they figure out some nonsensical consequences by themselves -no proper maths involved ever-. It's depressing. Baez is right, of course. I've been checking the (Word-generated) "papers" from this guy's gro…

> I've been checking the (Word-generated) "papers" from this guy's group at NASA, they're extremely shoddy. Not defending this particular paper, but I'm curious why you highlighted the fact that it's written in Word. Just about everybody in physics these days uses Word to compose papers (Word + Mendeley is a dream, by the way). Maybe you think he's not a 'real man' because he doesn't sling raw LaTeX?

What university is publishing papers in Word?

Re: Questions about Nasa's space drive answered

#190

Post by cratermoon »

gilgoomesh wrote: post #98
gus_massa wrote: post #80

Short version: Unless they believe the machine breaks some of the fundamental physics laws, the device must emit something. With this definition using a red LED Laser powered by a 1.5V battery in the back of the spacecraft is a "no reaction mass" thruster. The problem is that the momentum / energy ratio has theoretical limitations, and they are getting too much momentum. Long version (based on a previous comment http…

NASA suspects the thrust comes from "quantum vacuum virtual particles". These literally come from nowhere and would be the balance in the conservation of momentum. See Casimir Effect or Hawking radiation for examples where quantum vacuum virtual particles have an effect.

Quantum Vacuum Virtual Plasma: http://xkcd.com/1404/
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