No, German Scientists Have Not Confirmed the “Impossible” EMDrive

io9.com ^ | 7/28/15 10:40am | George Dvorsky

[Red Badger]

We'll see if this is real or another 'cold fusion' story......................

[IC Ken]

I am skeptical of what a modified microwave can do here.
I suspect an idea that is begging for money / funding.

[Veggie Todd]

Kirk: Spock, where the hell's the power you promised?
Spock: One damn minute, Admiral.

[Sasparilla]

Who needs that when you can just use your Interrositer?

[DiogenesLamp]

“The microwave cavity thruster as set-up by Tajmar continues to violate momentum conservation and thus does not work as advertised,”

This strikes me as a "no true Scotsman" fallacy.

[Jack Hydrazine]

I was really looking forward to that 18 month slog to Pluto!

[Lee'sGhost]

But...it has graphics.

[Sergio]

Physics question for those smarter than I am (can you say everyone?)

Newton's Law - for every action there is an equal and opposite reaction.

Given that, wouldn't the top speed of any interstellar craft be limited to, or less than, the speed of whatever is coming out of the tail end of the craft?

Asked another way, if you have a rocket, in a vacuum, with an exhaust speed of 15,000mph, would the rocket be able to travel faster than 15,000mph?

[Red Badger]

You’re mixing up the terms ‘speed’ vs. ‘acceleration’.

Constant acceleration will yield an increase in speed, even if slowly accelerated....................

[Red Badger]

http://www.edinformatics.com/math_science/acceleration.htm

[Sergio]

Thanks for the information, especially the link.

[bunkerhill7]

It`s true.
When I turn on my microwave, the flat round thing inside goes `round and `round and never stops until I turn it off or set the timer.

[arthurus]

They are skeptical and rightly so until one of these things gets off the ground which may well happen. It is about time in the technology evolution cycle for such a breakthrough.

[Red Badger]

From Google:

1 N is the force of Earth's gravity on a mass of about 102 g = (1⁄9.81 kg). On Earth's surface, a mass of 1 kg exerts a force of approximately 9.81 N [down] (or 1.0 kilogram-force; 1 kgf = 9.80665 N by definition).

From the article:

the researchers observed apparent thrusts of ~20 micro-Newton

So we're not talking much 'force' of acceleration here.................

[Boogieman]

“The microwave cavity thruster as set-up by Tajmar continues to violate momentum conservation and thus does not work as advertised,” says Eric W. Davis, a Senior Research Physicist at the Institute for Advanced Studies at Austin.

---

What hogwash. Sure, it appears to be in violation of conservation of momentum, but if it works experimentally, then obviously that is not an impediment. Perhaps the law is not actually violated somehow, or the law is not as inviolable as we suspected (if the device works).

[Red Badger]

It may be a ‘quantum’ device. If so, then the Newtonian Laws go out the window..................

[Moltke]

Not confirmed? Well, so much for the V3.

[Red Badger]

I’ve noticed my microwave turntable turns in opposite directions every time I turn it on..............I guess that way it is and ‘equal and opposite reaction’..................

[Boogieman]

“Given that, wouldn’t the top speed of any interstellar craft be limited to, or less than, the speed of whatever is coming out of the tail end of the craft?”

Well, what needs to be equal is not the velocities but the forces, and the force equals the mass times the acceleration.

So, a spacecraft generally shoots particles of very small mass at high acceleration out the back of the ship, which generates an equal force towards the front of the ship. However, because the ship is much more massive than the particles of propellant, the acceleration of the ship is much less than the acceleration of the particles.

Now, since spacecraft operate in a vacuum, the velocity will increase as long as they maintain that acceleration. Really, the velocity is limited by practical limits, like how much fuel the craft can carry, or whether the craft gets assistance from gravity using maneuvers to accelerate. As a certain point, there would be a hard limit to acceleration, as you approach the speed of light, but we can’t get anywhere near that, so it’s pointless to worry about.

[Rockingham]

Funny that you mention cold fusion because physicists here and abroad are again working on it, both experimentally and in search of a sound theoretical framework. A practical cold fusion device seems to have been invented and to have passed several third party verification tests. The rights were purchased by a North Carolina investment group and an initial production run is expected soon, with the devices used to provide hot water for large commercial applications. A comprehensive peer-reviewed paper by outside experts is also said to be in preparation.

I think that the EM Drive may move along a similar path but at a more rapid pace. As positive experimental results accumulate, they will be disputed by naysayers. Yet, assuming that the science is valid, preliminary working devices will soon follow and be tested in orbit, by NASA, and perhaps the Chinese, the European Space Agency, the Russians, and the Indians. In addition, tech titans Google and Apple are both sitting on immense stockpiles of cash and aching for new tech fields to conquer.