"Impossible" Drive

http://www.wired.co.uk/news/archive/2014-07/31/nasa-validates-impossible-space-drive

I suspect a thrust of 30-50 micronewtons comes at an energy cost to produce those microwaves many many times that.

Granted, if the satellite is close enough to the sun to have functional solar power this MIGHT be usable. But so are solar sails.

How much is 30 micronewtons?  Just enough to counter solar wind.
http://nmp.jpl.nasa.gov/st7/TECHNOLOGY/thrusters.html

People keep not believing it, and testing it, and finding it works. Pretty funny.

'IMPOSSIBLE' EM PROPULSION ENGINE CONFIRMED BY SCIENTISTS

Well, having just enough thrust to counter solar wind means we might be able to get to Mars in 70 days, but we wouldn't be able to get back, which is "upstream" so to speak.

Also, until we know WHY it works I wouldn't close the book on whether or not it really works or is just some anomalous test result.

Quote :

Martin Tajmar, the German scientist who has been independently testing the EM Drive, has a history of debunking experimental propulsion systems. So far, the drive appears to work, even in a vacuum. More testing is required to examine exactly how it works, and whether it is viable for use.

An anomalous test result that's reproduced by three or four independent test teams is stretching credulity almost as much as the idea of the drive working. I'm waiting with great interest.

Also, I don't know that 30-50 mN is any sort of theoretical limit. Even if it is, since fuel isn't an issue, you could stick a cluster of a bunch of thrusters on the back of your craft (why not?). That would goose your total up a bit.

richard09 wrote:

An anomalous test result that's reproduced by three or four independent test teams is stretching credulity almost as much as the idea of the drive working.

Only if they're not controlling for the same interference.

Solar wind? Cosmic rays? Neutrinos?

I add Micro-Newtons and Neutrinos to Trail Mix. Really tasty.

Now if science could just devise a way for me to get reliable internet connection, I would be happy.

Curiouser and curiouser.

Emdrive may be explained by quantized momentum, New Emdrive experiments are showing thrust replication and superconducting Cannae drive demo set for May 2016

Curious for sure. It's an intriguing project, but I wonder about its validity outside of the lab.
They show a picture of their experimental machine "ready for cryogenic operation." To me, that means that it depends on the Josephson effect for operation, which seems reasonable given its overarching theory. If so, then the device would only be active in cold regions of space. That limits its potential significantly. Potential for what, I couldn't envision.

I thought all of space was cold -- except in direct sunlight of course.

There are huge sections which are full of incredibly hot gasses. Millions of degrees.

But on the bright side, there is no definitive evidence of significant rainfall in space.

"Huge sections"? You mean like 0.0000000000000000000042 percent?

Rather than depend on the "How Things Works" web site, which gives the number you referenced, I looked to see what NASA had on it. According to this NASA article, dark matter makes up about 26% of the universe, with normal matter making up something less than five percent. So around thirty percent of the universe is matter according to NASA data.

For the mechanism under discussion, however, the concern would be the amount of matter in our galaxy.

_Howard wrote:

So around thirty percent of the universe is matter according to NASA data.

Hogswallop.

Wikipedia wrote:

The standard model of cosmology indicates that the total mass–energy of the universe contains 4.9% ordinary matter, 26.8% dark matter and 68.3% dark energy.[2][3] Thus, dark matter constitutes 84.5%[note 1] of total mass, while dark energy plus dark matter constitute 95.1% of total mass–energy content.[4][5][6][7] The great majority of ordinary matter in the universe is also unseen, since visible stars and gas inside galaxies and clusters account for less than 10% of the ordinary matter contribution to the mass-energy density of the universe.[8]

But that's only the composition of the mass-energy of the universe.

Outside of that mass-energy there's 99.999 999 999 999 999 999 999 999 999 999 999 999 999 82 % vacuum around it.

NoCoPilot wrote:

Outside of that mass-energy there's 99.999 999 999 999 999 999 999 999 999 999 999 999 999 82 % vacuum around it.

According to that article, that number is correct is all of the mass in the universe is packed as tightly as in a neutron star, "around 500,000,000,000,000,000 kg per cubic meter."

Are you asserting that it must be packed that tightly to be considered matter? That would leave us, and the earth, and most of our galaxy out of the definition.

Maybe I misread the article, but that isn't how I read it.

Quote :

On the other hand... if you consider how tightly matter can be packed... well, the densest thing that we know exists is a neutron star. The mass density inside a neutron star is around 500,000,000,000,000,000 kg per cubic meter (that would be 17 zeroes). On the other hand, the aforementioned critical density of the universe is about 0.000 000 000 000 000 000 000 000 01 kg per cubic meter (that would be 25 zeroes after the decimal point). So this means that the universe is 99.999 999 999 999 999 999 999 999 999 999 999 999 999 82 % empty (that would be 39 '9'-s after the decimal point.)

The sentence is poorly written.

To be fair, as the article writer points out, it's hard to talk about "the vacuum of space" because each square light year of space contains SOME atoms of hydrogen, as well as the vacuum energy of particles spontaneously appearing and annihilating. So it's hard to measure the emptiness of space.

I was intentionally oversimplifying, so that we could discuss the percentage of matter versus empty space. I still believe my approximations were correct, and yours were approximations of what percentage of matter is dark matter -- not what percentage of space is matter. Thirty percent? Preposterous.

Well, those were not my approximations; they were from NASA's astrophysics web page. They give a value of about five percent of the universe being composed of "normal" or visible matter and about 27 percent composed of dark matter. Granted, if you compressed that matter with the pressure of a neutron star, it would take up a much smaller space, as the data that you presented indicated. But it is not, in fact, so compressed.

Nope, read it again.

There certainly are conflicting answers available for this question on the all-knowing internet.

There is the answer you present, which seems to me to be more concerned with mass density than with matter. Then there are those answers such as this one, which are quite consistent in their measurements, e.g., "Measurements from WMAP resolve several long-standing disagreements in cosmology rooted in less precise data. Specifically, present analyses of the WMAP all-sky image indicate that the universe is 13.7 billion years old (accurate to 1 percent), composed of 73 percent dark energy, 23 percent cold dark matter, and only 4 percent atoms."

The article you referenced wrote:

the Universe, which now averages a frigid 2.73 degrees above absolute zero temperature

Would this be true if the Universe was 30% matter?

Apparently.
But most of that matter is dark matter, which is still hypothetical.
In any case, I don't see why there would be a conflict. Matter is the temperature of its background, unless it is acted upon by a heating energy.