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EmDrive  (Source:
It's a a propellantless microwave thruster that defies Newton's laws of motion

Chinese scientists have taken on a heavily criticized space drive idea that could one day launch satellites, deep space probes and even flying cars.

The research team hails from Northwestern Polytechnic University in Xi'an, and was led by Yang Juan. What they developed was a propellantless microwave thruster called EmDrive, which is a controversial idea because it goes against Newton's laws of motion -- and many have claimed to create a "propellantless" thruster before and failed.

Newton's laws of motion are all based on the idea that firing propellant out of the back at a high speed will push a craft forward. While solar cells offer infinite power, thrust is limited by propellant. Many have tried to get around this, but several scams have made this particular field a joke in the scientific world.

While space drives tend to rely on Newton's laws of motion, the EmDrive is a closed, conical container that has a net thrust toward the wide end when filled with resonating microwaves. This goes against Newton, who said that no closed system could have a net thrust. However, EmDrive works because the microwaves have a group velocity (the speed of a collection of electromagnetic waves) that is greater in one direction than the other -- which is where Albert Einstein's theory of relativity comes in.

British engineer Robert Shaywer, who began looking at the concept of a propellantless thruster when he opened his own company called Satellite Propulsion Research in 2001, is the original creator of the EmDrive. He made demonstration thrusters to prove it could be done, and even made sure the test results were accurate (meaning, the results weren't affected by friction, ionization, air currents, electromagnetic effects or interference). The first, made in 2003, had a thrust of 16 mN. This was enough to show it could be done.

However, he received a ton of criticism for his idea and was ridiculed in his own country. But the Chinese team at Northwestern Polytechnic University believed in his research and took the project head on to author the latest study, "Net Thrust Measurement of Propellantless Microwave Thruster."

The Northwestern Polytechnic University team was able to create the EmDrive with 720 mN of thrust with a couple of kilowatts of power.

So what purpose does EmDrive have? It could halve launch costs of satellites because as much as half the launch weight of these objects are attributed to propellant.

Shawyer is even working on a superconducting thruster that could be ready as soon as 2016. It would boost the Q value of the cavity, which determines the amount of thrust produced. He said it could be boosted by a factor of several thousand, possibly equating to a tonne of thrust per kilowatt of power.

Source: Wired

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RE: Interesting...keep moving forward
By Shadowself on 2/11/2013 5:02:31 PM , Rating: 3
As you correctly pointed out, laws are basically our tenants on how things work.
Not true. "How" things work is the theory.

Pick up a rock and release it. I falls. Pick it up again and release it again. It falls. Do that one billion times and the rock falls every time. That's the LAW of gravity. Laws are the simple, observed facts. They don't change. Our understanding of HOW it works can change. The HOW is the theory.

Now "how" gravity works, e.g., the inverse square relationship (note I did NOT say inverse square LAW) is a theory. As I mentioned there have been a few experiments in the last several years that have cast a tiny bit of doubt on gravity following an inverse square relationship. So the Theory *MIGHT* need to be tweaked. However, the LAW still holds.

Unfortunately, as I mentioned before, many, many people confuse Physical Laws with Theories about the Physical Laws. They are not the same. Not even close.

Relativity was an example that violated traditional Newtonian physics, but our definition of the law was modified to account for it. The fundamental physics never change, but our understanding of the laws do.
No. Simply, No. The Law does not change. Newton's theory on how gravity works was flawed (mostly correct, but not quite). Einstein's theory of General Relativity modified Newton's theory. It did not change the law or modify our understanding of the law. Relativity modified the theory. It modified how we try to explain the law.

By theapparition on 2/19/2013 4:13:34 PM , Rating: 2
You're arguing semantics, and quite wrong at that I might add.

There is no such thing as a "Law" other than what we, as a human race, has determined to be a law.

The fundamental physics is the law, of which we only have a superficial understanding. We have then divided portions of that physics we think we understand into scientifically proven directives that we call "Laws". Your concept of a law as an observed phenomenon (eg drop rock billions of times) is incorrect and not supported by the scientific community. You can adopt your own bastardized definition of a "law" anyway you want, and then attempt to argue from that vantage point. I won't indulge you.

The quote I mentioned before about a scientific law going on trial if violated was from the late, great Carl Sagan. But I'm sure he had no idea what he was talking about.

"We don't know how to make a $500 computer that's not a piece of junk." -- Apple CEO Steve Jobs

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