After ten weeks the EMdrive is still running at NASA

originally posted by: Thecakeisalie

originally posted by: scubagravy
would it not be harder to dodge debris the faster we go? and at that speed even a grain of sand would cut like a laser ?

Space is not empty and is full of gamma rays, dust particles and other dangers. Even If we could travel at the speed of light we'd need a shield or we'd perish.

Look at the Large Hadron Collider- two particles colliding at near light speed creates tremendous energy; Imagine flying through space at near light speed where millions of particles collide with your ship every second. It's impossible at our level of understanding.

tremendous is relative though. a dust mote at .25 c has the Kinetic impact power of a high powered rifle bullet. not socially friendly but definitely not beyond our ability to neutralize safely. and that sort of object is the most probable impact to occur. at about 1 impact (of a dust mote sized object) per square meter of frontal cross section of the craft per day of travel. each size step up is exponentially more rare. and dust motes and sand grains are definitely deflected by electrostatic or dynamic electromagnetic fields. just look at any old crt or tube type TV screen. so you can armor up the front and you can create an field to deflect such impactors.

a reply to: stormbringer1701

I doubt these particles would have time to be repelled by a shield.

originally posted by: deadeyedick
a reply to: stormbringer1701

I doubt these particles would have time to be repelled by a shield.

not knowing about the current knowledge about that it would seem logical. But i know what the current state of knowledge is on such things. (one of the benefits of benefits of being a voracious consumer of advanced space technology articles for all of my life.) the fact is a device the size of a coffee can (not counting tankage and plumbing) can generate a suitable field of magneto plasma tens of kilometers to hundreds of kilometers in diameter. it "self inflates" by absorbing particles from the stellar wind though it is somewhat lossey.

if you have a hundred kilometer buffer to begin moving stuff out of the way it should certainly be enough time. i might worry about it if you could get to the extreme upper end of relativistic speed. even then since the thing is moving and motion is relative it might just push stuff out of the way faster.

think about it though. a couple of layers of sand bags completely absorbs the kinetic energy of high powered rifle bullets. so the impacts from a dust mote (which are the bullet equivalent) or even sand grain should not require extraordinary levels of armor. its the much rarer peas and even rarer marbles that you might need the advanced armor to handle.

originally posted by: stormbringer1701

originally posted by: deadeyedick
a reply to: stormbringer1701

I doubt these particles would have time to be repelled by a shield.

not knowing about the current knowledge about that it would seem logical. But i know what the current state of knowledge is on such things. (one of the benefits of benefits of being a voracious consumer of advanced space technology articles for all of my life.) the fact is a device the size of a coffee can (not counting tankage and plumbing) can generate a suitable field of magneto plasma tens of kilometers to hundreds of kilometers in diameter. it "self inflates" by absorbing particles from the stellar wind though it is somewhat lossey.

if you have a hundred kilometer buffer to begin moving stuff out of the way it should certainly be enough time. i might worry about it if you could get to the extreme upper end of relativistic speed. even then since the thing is moving and motion is relative it might just push stuff out of the way faster.

think about it though. a couple of layers of sand bags completely absorbs the kinetic energy of high powered rifle bullets. so the impacts from a dust mote (which are the bullet equivalent) or even sand grain should not require extraordinary levels of armor. its the much rarer peas and even rarer marbles that you might need the advanced armor to handle.

Traveling at half light speed, with a 100 kilometer buffer ahead to clear the way, would give you 0.0006 of a second to get the job done before your 'ship' hits the debris.

Also, the energy from one gram of mass at that velocity is 4.5 x10^13 Joules. For comparison, the Hiroshima A-Bomb released 6.3 x 10^13 Joules. So we aren't talking about stopping the energy of a bullet, but more of stopping the energy similar to that of a tactical nuclear weapon (per gram).

a gram weight particle is a rare thing in space. no... a dust mote in space is rare. a gram weight is fantastically rarer. the local area of the sag.perseus arm experienced some event, probably a super nova, that virtually wiped this area free of interstellar dust bunnies. you could go the entire distance without even passing within 100K kilometers of anything larger than a dust grain.

also the 100 KM diameter thing is not an upper limit. it's merely what Dr WingLee and others calculated for a mini-magneto plasma sphere generated by the size of device Dr WingLee was currently working on. the plasma sphere is self inflating meaning that once you have the initial field and inject some starter plasma incident stellar plasma (at least inside the heliosphere) causes the initial sphere to grow larger and more and more charged with plasma.

Staying hopeful! Hey OP, the image in the post is of an ION drive, not the EM drive. Just sayin'.

a reply to: stormbringer1701

I think a sharp coned craft would deflect debris easier than if you build something that's to wide .

And I guess if they going to build something , it will take years of space testing, to see the effect of spaceflight under these extreme conditions.

So before we will see the first satellite craft flying up there , I guess we are at least ten years ahead of where we are now.

Since, I may have missed any mention. The Dick Tracy MagnaCoupe, classic comic strip Earth to Moon vehicle.

Since, I may have missed any mention. The Dick Tracy MagnaCoupe, classic comic strip Earth to Moon vehicle.

Could be the EMdrive is our first warp drive.

In recent experiments NASA’s Eagleworks research group tested the potential warping of space in a device similar to the EmDrive by using interferometer measurements. The interferometer uses the interference of two laser beams to measure extremely small perturbations of space....

Although slight interference was observed, indicating a micro-warping of spacetime around the test device, the apparatus must be tested next in a vacuum chamber to rule out atmospheric influences (although calculations show that the level of interference cannot be attributed to atmospheric influences of the test beam).

link

originally posted by: stormbringer1701
a gram weight particle is a rare thing in space. no... a dust mote in space is rare. a gram weight is fantastically rarer. the local area of the sag.perseus arm experienced some event, probably a super nova, that virtually wiped this area free of interstellar dust bunnies. you could go the entire distance without even passing within 100K kilometers of anything larger than a dust grain.

also the 100 KM diameter thing is not an upper limit. it's merely what Dr WingLee and others calculated for a mini-magneto plasma sphere generated by the size of device Dr WingLee was currently working on. the plasma sphere is self inflating meaning that once you have the initial field and inject some starter plasma incident stellar plasma (at least inside the heliosphere) causes the initial sphere to grow larger and more and more charged with plasma.

The Busard Ramjet was theorized to work by concentrating Hydrogen from the interstellar medium and using it to produce a fusion reaction which powers the drive. Regardless of the issues with the actual function of such an engine, there is an interstellar medium which does have significant matter. Although it is not all conglomerated into a single mass, a spacecraft traveling at high velocity would encounter that mass, no matter how diffuse, and the energy released (even from a diffuse cloud) would have to be dealt with. Over interstellar distances, and at velocities close to light speed, the issue would be a major engineering problem, the mitigation of which, would add mass to the spacecraft, limiting its velocity and vastly increasing power requirements.

Like many great scifi concepts, when you do the maths, you encounter issues that are beyond our technology and may well not have a technological solution. I'd love it if it did work and we could get out there among the stars. Perhaps one day it will.

Wrong thread

There was an update in another thread from the MIT Technological Review.

ATS link: Ask any question you want about physics

The article describes Unruh radiation and a new method of describing inertia. There is also two predictions made by author. 1 - Adding a dielectric inside the cavity should boost performance; and, 2 - Changing dimension of the cavity will reverse direction of the thrust.

The quantum field rears its crazy, foamy head again. Seems like all particles are interacting will all other particles and when you limit how they interact the result is a re-conversion of inertia back to thrust in the opposite direction from which they came in.

originally posted by: stormbringer1701
a gram weight particle is a rare thing in space. no... a dust mote in space is rare. a gram weight is fantastically rarer. the local area of the sag.perseus arm experienced some event, probably a super nova, that virtually wiped this area free of interstellar dust bunnies. you could go the entire distance without even passing within 100K kilometers of anything larger than a dust grain.

also the 100 KM diameter thing is not an upper limit. it's merely what Dr WingLee and others calculated for a mini-magneto plasma sphere generated by the size of device Dr WingLee was currently working on. the plasma sphere is self inflating meaning that once you have the initial field and inject some starter plasma incident stellar plasma (at least inside the heliosphere) causes the initial sphere to grow larger and more and more charged with plasma.

And how many such impacts would it take to become a problem?
This is one of those instances where one would seem to be enough.

a reply to: tinymind
Just wandering through old tags. There is a metallic foam that is light enough to rest on a dandelion seed head, but can withstand the impact of a .50 caliber armor penetrating round. That there will occur better products for the protection of interstellar vehicles is implied by developing interstellar vessels. When it is time to railroad, you will railroad.

UPDATE

The EM has shown thrust that, until now has been unexplained. The hopes and dreams of us land lubbers traveling amongst the star were boosted by the idea that during a couple data runs, against known physics, the thing might actually work!

[P]hysicist at Dresden University of Technology [...] are saying those promising results were all false positives that are explained by outside forces.

Popular Mechanics, March 31, 2021 - Scientists Just Killed the EM Drive.

In a a series of three papers, the article says, not only did they recreate the NASA results but by changing the drive’s mount points, eliminate the reading.



The controversy continues?? Or is it the nail in the coffin??

originally posted by: TEOTWAWKIAIFF
The controversy continues?? Or is it the nail in the coffin??

I thought the coffin was well set up in 2018 and that NASA would confirm the false positive by now, but I didn't see anything yet about NASA confirming the false positive.

I suppose NASA could keep trying, but they should be able to confirm one way or the other if they can duplicate the Dresden University results showing it was a false positive. NASA has had three years to respond to the paper this article is about, from March 2018, have they responded?

Latest EmDrive tests at Dresden University shows “impossible Engine” does not develop any thrust
That was three years ago.

I heard the DARPA funding runs out in May 2021, that should be the end unless a flaw is found in the Dresden University research, but given physicists said the "false positive" was breaking the known laws of physics, it's not too hard to accept the Dresden results saying the known laws of physics are being followed, it was a measurement problem.

a reply to: Arbitrageur

I thought that the X-37B was running the real tests. This is the academic side,?so it takes time (the PM article says the papers show “3 orders of magnitude”, whatever that means, significance in papers is typically in sigmas, but it it popular Mechanics after all!).

Both articles are about the March publications of the three papers.

Personally, I want to see the plasma jet engines make the prototype stage!

originally posted by: TEOTWAWKIAIFF
a reply to: Arbitrageur

I thought that the X-37B was running the real tests.

Rumors?

Rumours The US Military Is Testing an EM Drive on The X-37B Space Plane Just Won't Die

Things got particularly interesting in December, when the Chinese government claimed they were already testing an EM Drive in space, and an anonymous source told the IB Times that the US was doing the same thing on board the military's mysterious space plane, X-37B. Five months later and those rumours are still circulating on blogs and news sites. So what's going on?

From a scientific perspective, taking something that's barely measurable in the lab and trying to measure it aboard the X-37B doesn't make any sense, because it will just add more variables that are difficult to account for. (unless it was a model that is supposed to have a lot more thrust than the lab version).

If China really is trying to test it, maybe that was the goal of starting the rumors?

"so that the force is generated by the interaction between
the EM Drive and the magnetic field of the earth"

So you get 1/4 the way from earth and the power dies!
No magnetic field from the earth.
just have to drift the rest of the way.

just hope the magnetic field of mars
will stop you. I bet it is weaker. splat.