To The Stars, Alice!

Chinese Test EM Drive in Space - China claims to have a working version of NASA's impossible engine orbiting the Earth - and will use it in satellites 'imminently'

Scientists in China claim they’ve created a working prototype of the ‘impossible’ reactionless engine – and they say they’re already testing it in orbit aboard the Tiangong-2 space laboratory.

The radical, fuel-free EmDrive recently stirred up controversy after a paper published by a team of NASA researchers appeared to show they’d successfully built the technology.

If the physics-defying concept is brought to reality, it’s said the engine could get humans to Mars in just 10 weeks.

But now, scientists with the China Academy of Space Technology claim NASA’s results ‘re-confirm’ what they’d already achieved, and have plans to implement it in satellites ‘as quickly as possible.’

It's kind of a shame that NASA has been converted from an agency that actually researches space-flight into one the promotes Muslim outreach into STEM and proselytizes reverting to a 19th century life style to halt "climate change", but that's where we are. Maybe The Donald will be able to change that; maybe not

Meanwhile, the Chinese are getting ready to go to the stars. Maybe those stories about Ming the Merciless, Princes Aura, and the hapless Flash Gordon will turn out to have some relevance after all.

Wombat-socho at The Other McCain steps up with "Rule 5 Sunday: Happy New Year!"

Using Dark Matter to Explore the Stars?

Continuing the strange story of the mysterious EMdrive, which appears to defy Newtons Law, and produce thrust without reactions mass: Could Dark Matter Be Powering The EMdrive?

For every action, there's an equal and opposite reaction. This formulation of Newton's third law has two very important modern consequences: one, that there's a physical quantity that's always conserved in the Universe (momentum), and two, that the laws of physics are the same irrespective of your position in space. This has a huge slew of implications, including that if you want to power a device to change its motion, you need to push against something. This could be exhaust from a rocket, tires pushing against a road, train wheels on a rail-line or even photons reflected off a sail. The one thing that's forbidden is a reactionless drive: an action without a reaction. That's exactly what the EMdrive -- the "impossible" space engine just verified by a NASA test -- claims to be. If it truly works as advertised, it violates the laws of physics. But there's a possible loophole: perhaps there is a reaction, and we just don't detect it. Perhaps the reaction occurs, but it's occurring due to dark matter.

EMdrive in action?

According to the standard model of cosmology, the majority of the matter in the Universe isn't in the form of atoms, or of any known particle. Rather, the overwhelming majority of mass -- by a 5-to-1 margin -- is in the form of dark matter. Dark matter doesn't collide, annihilate or otherwise interact with either itself or other, normal matter under any known circumstances, but rather interacts only gravitationally. After 13.8 billion years like this, it forms a vast, diffuse cosmic network of gravitational structure, and forms huge spherical haloes more than a million light years in diameter that contain galaxies like our own. This means, all told, that dark matter permeates every square centimeter of our galaxy, including existing -- albeit in small densities -- inside every object on Earth, including our own bodies.

How would it work? At any point in time, there are dark matter particles passing through all regions of space, undeterred by the presence of matter or other Standard Model particles. Inside the electromagnetic cavity, photons of a particular frequency bounce around in all directions, conserving momentum and generating no thrust. But if photons moving in a particular direction -- towards the "back" of the cavity, for example -- are likely to strike a dark matter particle, three things ensue:

• The photon changes momentum, and moves "less backwards" and "more forwards" than before it struck the dark matter particle.
• The photon strikes the inside wall of the cavity, reflecting off of it and imparting its momentum in the forward direction to the cavity itself.
• The struck dark matter particle gains momentum as well in the opposite direction: backwards.

Momentum is conserved because the dark matter carries it away, equal and opposite in magnitude to what the cavity absorbs.

If this is what's truly going on, it would be revolutionary. Because dark matter is everywhere, it means that we'd only need a power source -- not fuel -- to travel anywhere in the galaxy we wanted, because every location in the galaxy contains substantial amounts of dark matter. It means that we'll have a method for detecting dark matter that was stumbled upon accidentally, and that dark matter is verified to exist. And most importantly, it means that the laws of physics aren't broken after all; momentum is still conserved.

I really like this. It preserves Newton's Law, which has held up pretty well until now, shows a way forward to detecting dark matter directly, and offers a way to get to the stars (without throwing everything away as reaction mass). It does, however, have some drawbacks. Even if dark matter outweighs "our matter" 5 to 1, its spread rather thing (ours, by contrast, is quite lumpy), and the amount of thrust must ultimately be limited by the amount of dark matter the engine "runs through", although I doubt the engine as now contructed is anywhere near optimal.

Hmm, does this mean it speeds up like a ram jet as it accelerates? I'll leave that question to the real physicists.

Wombt-socho has "Rule 5 Sunday: Maid of Meat" up and running at The Other McCain.

Star Trek "Impulse" Drive Comes Closer to Reality

Bring on the Green Girls! The Curious Link Between the Fly-By Anomaly and the “Impossible” EmDrive Thruster

About 10 years ago, a little-known aerospace engineer called Roger Shawyer made an extraordinary claim. Take a truncated cone, he said, bounce microwaves back and forth inside it and the result will be a thrust toward the narrow end of the cone. Voila … a revolutionary thruster capable of sending spacecraft to the planets and beyond. Shawyer called it the EmDrive.

Just catch a few rays on your solar/stellar panels, send the electricity to the EmDrive, and voila, propulsion without wasting reaction mass. But there's a pesky little problem with one of Newton's Laws.

Shawyer’s announcement was hugely controversial. The system converts one type of energy into kinetic energy, and there are plenty of other systems that do something similar. In that respect it is unremarkable.

The conceptual problems arise with momentum. The system’s total momentum increases as it begins to move. But where does this momentum come from? Shawyer had no convincing explanation, and critics said this was an obvious violation of the law of conservation of momentum.

Shawyer countered with experimental results showing the device worked as he claimed. But his critics were unimpressed. The EmDrive, they said, was equivalent to generating a thrust by standing inside a box and pushing on the sides. In other words, it was snake oil.

If I only had $5  for every proposal for a perpetual motion machine; but I digress.

Since then, something interesting has happened. Various teams around the world have begun to build their own versions of the EmDrive and put them through their paces. And to everyone’s surprise, they’ve begun to reproduce Shawyer’s results. The EmDrive, it seems, really does produce thrust. . . And last year, NASA conducted its own tests in a vacuum to rule out movement of air as the origin of the force. NASA, too, confirmed that the EmDrive produces a thrust. In total, six independent experiments have backed Shawyer’s original claims.

So put one in space with some solar panels, a little machinery to navigate with, and see if it flies!

That leaves an important puzzle—how to explain the seeming violation of conservation of momentum.

The answer is that they don't really know yet, but theories they have will challenge physics as we know it.

Today we get an answer of sorts thanks to the work of Mike McCulloch at Plymouth University in the U.K. McCulloch’s explanation is based on a new theory of inertia that makes startling predictions about the way objects move under very small accelerations.

First some background. Inertia is the resistance of all massive objects to changes in motion or accelerations. In modern physics, inertia is treated as a fundamental property of massive objects subjected to an acceleration. Indeed, mass can be thought of as a measure of inertia. But why inertia exists at all has puzzled scientists for centuries.

McCulloch’s idea is that inertia arises from an effect predicted by general relativity called Unruh radiation. This is the notion that an accelerating object experiences black body radiation. In other words, the universe warms up when you accelerate.

According to McCulloch, inertia is simply the pressure the Unruh radiation exerts on an accelerating body.

Something here doesn't link, at least to me. Does the universe push back against hot objects? Not that I've heard of.

That’s hard to test at the accelerations we normally observe on Earth. But things get interesting when the accelerations involved are smaller and the wavelength of Unruh radiation gets larger.

At very small accelerations, the wavelengths become so large they can no longer fit in the observable universe. When this happens, inertia can take only certain whole-wavelength values and so jumps from one value to the next. In other words, inertia must quantized at small accelerations.

McCulloch says there is observational evidence for this in the form of the famous fly by anomalies. These are the strange jumps in momentum observed in some spacecraft as they fly past Earth toward other planets. That’s exactly what his theory predicts.

Testing this effect more carefully on Earth is hard because the accelerations involved are so small. But one way to make it easier would be to reduce the size of allowed wavelengths of Unruh radiation. “This is what the EmDrive may be doing,” says McCulloch.

If this is true, the rules of physics are stranger than we've imagined

McCulloch’s theory could help to change that, although it is hardly a mainstream idea. It makes two challenging assumptions. The first is that photons have inertial mass. The second is that the speed of light must change within the cavity. That won’t be easy for many theorists to stomach.

But as more experimental confirmations of Shawyer’s EmDrive emerge, theorists are being forced into a difficult position. If not McCulloch’s explanation, then what?

Proving Newton's Laws wrong is one thing, Einstein did that a century ago now, at least at the margins.  But the constancy of the speed of light in integral to Einstein's theories of Relativity. They've been trying for years, and no one has proved Einstein wrong yet.

Wombat-socho has the giant "Rule 5 Sunday: Blue Shirt Double-Dip Edition" ready at The Other McCain.