Reactionless drives...

nsaspook

Joined Aug 27, 2009
13,306
http://www.forbes.com/sites/ethansiegel/2015/05/04/no-nasa-did-not-accidentally-invent-warp-drive/
One of the most famous things Richard Feynman ever said was, “The first principle is that you must not fool yourself – and you are the easiest person to fool.” When you come across an announcement like the one made by NASA Spaceflight a week ago: that NASA has made a successful test of the EM Drive — a propulsion engine that uses no propellant, seemingly violating one of the most fundamental laws of physics, while warping space in the process — you’d better make sure you aren’t fooling yourself.
 

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cmartinez

Joined Jan 17, 2007
8,257

they claim that the acceleration seen is consistent with the warped space of an Alcubierre Drive, the hypothetical “Star Trek” design.

The original article never claimed such a thing, this is a new development.

The claimants propose no viable mechanism, but merely contend that all of science is experimental
The original article did provide a "viable" mechanism, however, it is one that is not easy to understand, and the serious scientists that have actually studied it have found it flawed

The device simply exists and is in the hands of NASA Eagleworks, where engineer Paul March is performing further tests after initial tests by Sonny White, but so far, there is just the one team testing the one device.
This is true... and I'm glad it's being taken at least half-seriously

The possibility that this is merely a device doing absolutely nothing new under the Sun is too great, and one that we need to definitively rule out before proceeding further.
I agree. Let's rule it out by at least getting definite negative results.

To be honest, I'm not expecting much out of this... and no, it won't break my heart to see it go down in the long history of hoaxes or flawed theories, I'd very much rather learn the truth.

Thanks for the article
 

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cmartinez

Joined Jan 17, 2007
8,257
It seems that some overzealous fool was responsible for calling the latest development a "warp drive". Fortunately, the NASA guys have come forward to clarify things:

http://www.nbcnews.com/science/spac...a-downplays-impossible-em-drive-space-n357151

But they're still giving this thing serious consideration... if only to maybe at least discard it from their list of possibilities:

It's possible that electromagnetic leaks in the chamber or coupling with Earth's magnetic field are responsible for the supposedly impossible result, said Koberlein, who is based at the Rochester Institute of Technology. But the recent test in the vacuum chamber, if it is indeed valid, does rule out another prosaic explanation — that the engine was pushing against Earth's atmosphere in some way, he added.
 

nsaspook

Joined Aug 27, 2009
13,306
http://io9.com/no-german-scientists-have-not-confirmed-the-impossibl-1720573809
“My insight is that the EMDrive is complete crap and a waste of time,” Carroll tells io9. “Right there in the abstract this paper says, ‘Our test campaign can not confirm or refute the claims of the EMDrive’, so I’m not sure what the news is. I’m going to spend my time thinking about ideas that don’t violate conservation of momentum.”
http://www.iflscience.com/no-em-drive-will-not-lead-warp-travel-any-time-soon
One of the outlandish claims for the EM Drive is that it provides propellant-less propulsion but, again, this has never been proven. As the researchers explained in their paper: “Our test campaign can not confirm or refute the claims of the EM Drive but intends to independently assess possible side-effects in the measurements [sic] methods used so far.”
 
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cmartinez

Joined Jan 17, 2007
8,257
Apparently it has very cautious defenders:
What it actually does is produce a tiny, tiny amount of thrust via a method that’s not entirely understood.
“...[They] don’t say that they’ve validated the drive – just that they can’t explain where their teeny tiny thrust signatures are coming from.”
...It means that the EM Drive remains nothing more than a form of propulsion with a really low amount of thrust that scientists can’t completely explain. That won’t stop a host of places from telling you otherwise, though.
Just remember, if there’s no peer-reviewed research saying how it works (there isn’t) or experimental evidence of it producing high thrust (again, nope), then take everything with a hefty pinch of salt.
And ferocious detractors:
...when looking at previous EMDrive experiments, Davis noticed that the alleged thrust was generated slowly, and not instantaneously, when the electrical power was switched on.
...“This is a direct indication of a thermal effect in reverse (heating versus cooling), which produces a clear false positive thrust signal,” says Davis. “Tajmar has to account for and reconcile this fact as well in his data analysis which he apparently did not discuss in his paper. This would be another nail in the coffin against the existence of any real definite momentum violating thrust produced in the microwave cavity.”
...Critics of the EMDrive, of which there are many, say it’s all poppycock.
 

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cmartinez

Joined Jan 17, 2007
8,257
It seems that the EM drive is not the only far-fetched idea being considered by people with respectable credentials:

Some theorists are now breaking ranks to offer radical explanations, among them Dr Dragan Hajdukovic at Cern, who has developed a theory that gravitational polarity does exist. He says: "So far, we believe that gravity's only a force of attraction. It may be that gravity can also be a force of repulsion but not between matter and matter but between matter and anti-matter."
It's a theory Cern is gearing up to test next year. If Hajdukovic can show that anti-matter particles fall "upwards", he not only opens the way to some form of demonstrable anti-gravity on earth, he almost certainly wins a Nobel prize into the bargain.


http://www.bbc.com/news/magazine-35861334
 

BR-549

Joined Sep 22, 2013
4,928
This might be something to look into. If you could manufacture stable anti-matter dipoles.

In the model I study, gravity is not a fundamental property. It comes from the asymmetric dipole action. If a dipole were made with that asymmetry inverted, it would be an inverted gravity. If this model is correct

We should be able to see the effect with a few stable anti-matter H2 molecules. Regular H2 molecules bump their way up, anti-matter H2 would accelerate up with this property.

As soon as we can make and store them. They would have to be neutral molecules. And of course isolated from regular matter.

I have my doubt's about the gravitational aspects of this model. It's plausible to me for the attractive component of gravity, but I can't see the angular momentum component with that process. However, it took me over a year to realize anti-matter, so gravity might take a little longer(ha ha). I think that angular momentum has a larger part in it's generation. I still think it is not fundamental.

The trouble with EM is, the momentum is converted to angular momentum when absorbed. And if you use a reflector, the momentum is reflected with the EM. The energy goes with the frequency.
 

nsaspook

Joined Aug 27, 2009
13,306
The odds are enormous that it's experimental error (it starts gaining excess energy at a few thousand meters per second) but what the hell, I would love to have true space travel before I die.
 
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