
The SpaceDrive Project – First Results on EMDrive and Mach-Effect Thrusters - mynegation
https://www.researchgate.net/publication/325177082_The_SpaceDrive_Project_-_First_Results_on_EMDrive_and_Mach-Effect_Thrusters
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roywiggins
Given that reactionless thrust is even less plausible on a theoretical basis
than superluminal neutrinos, I really hope this doesn't come as much of a
surprise to anyone.

~~~
delecti
Not a surprise, but certainly a disappointment. It would have violated our
understanding of physics, but it's not like that's never happened before.

~~~
hn_throwaway_99
> It would have violated our understanding of physics, but it's not like
> that's never happened before.

I've heard this sentiment a lot when it comes to the EMDrive, but honestly I
think it really misunderstands how science progresses in general. For EMDrive
to be real, virtually everything we know to be true about physics would have
to be false: if you're saying conservation of momentum can be violated, or
conservation of energy can be violated, then basically all of modern physics
would have to be wrong.

When science, and especially physics, advances, it is very rarely, if ever
since Newton's time, that the settled physics is 100% wrong. Instead, the
"old" physics tends to be an approximation under most conditions, or there is
a new phenomenon that can be explained without really violating the old rules.
For example, conservation of momentum still holds under special relativity,
it's just that we discovered things without mass can have momentum.

Thus, the only explanation that would really be plausible is if there is
"something else" going on with the EMDrive where momentum and energy are still
conserved, just that there is something happening beyond our current
understanding of "energy" or "momentum". I haven't seen any explanations that
even try to postulate what that could be. All I ever have seen is "but the old
physics could be wrong!" without an explanation of _how_ it could be wrong.

~~~
Nomentatus
Horsefeathers. To name two examples. The Einstein-Podolsky-Rosen's paper on
entanglement “Can Quantum Mechanical Description of Physical Reality Be
Considered Complete?” (Einstein et al. 1935) ignored as trash for decades. The
Casimir effect was predicted from quantum theoretical calculations, but again,
no-one did the experiment for decades because they felt it was a trash
prediction that couldn't be true 'cause it ignored basic physical laws that
everyone knew had always held and always would. Empty space just couldn't do
that. And on and on and on - I've just covered this century a tiny bit, not
all the time since Newton. Dark energy anyone?

Knowledge of the mechanisms behind X doesn't always precede discovery of X
(why would anyone think it would always do so?) Lack of a known mechanism was
why John Newlands version of the periodic table was greeted with contempt, and
Mendeleev didn't find it easy sledding at first, either. But the contempt was
unjustified. Birds were able to fly before the airfoil was discovered or
airflow understood. Electricity was a broad field of study (Maxwell's
equations, etc) long before the electron was discovered. The how usually
trails the what in the history of science.

I won't be shocked if the Emdrive is a wrong turn, but the idea we could
_know_ that in advance is sciencism - the satanic inversion of science - not
empirical science.

~~~
whatshisface
There is still some place for using theoretical predictions to guide
experiments. For example, I have developed a rune that may be used to cast
Fireball - it consists of three triangles carved in to a very expensive gold-
titanium laminate. If that test fails, I suppose we also ought to try four
triangles, a triangle and a circle, the word 'fireball' engraved on the
perimeter of a hexagon, three triangles engraved onto a momentum-nonconserving
cone...

More seriously, there was a good reason to strongly suspect that the EM drive
wouldn't overturn physics: we have probed electromagnetic interactions at
energy densities far higher (gamma ray scattering) and far lower (radio
telescopes) and everything in-between, and they all seem to be points on a
continuous surface defined by Maxwell's equations applied to quantum
mechanics. A working EM drive would actually be very close to the magic rune I
described above: a wildly noncontinuous point where the laws of physics became
massively different for one particular arrangement of matter, and then go
right back to normal if you step in any direction around it.

~~~
Nomentatus
The general use of experiments in science (as opposed to a Homo Erectus
experimenting with rock types when making hammers) is to test what we think we
know, to see if it's really so. IIRC the "inventor" of the Emdrive had a
theory of his own to go by that led him to his device. We probably agree that
it's the use of theory to preempt and prevent any experimentation that is
pernicious.

(reply to below comment) While not all experiments are equal, there's no right
answer, and plenty of room for good and bad luck. The marketplace of ideas
ensures enough variety that we don't miss toooo much (maybe.) Yet very often,
it's those with the most eccentric and false ideas, such as Keplar, who
stumble onto the right path because at least they're looking where nobody else
is, for correlations no-one else thought to! So my bias is toward the most
novel experiments that are still extremely likely to fail, as I think you
agree.

Just this week I was reading up on the Stern-Gerlach Magnet experiment, which
discovered spin; something the experimenters absolutely weren't looking for.
The idiots (or recipients of blind luck) win a lot of rounds in science,
'cause they're at least trying something genuinely new.

Slightly different alloy = slightly different string theory?

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whatshisface
> _We probably agree that it 's the use of theory to preempt and prevent any
> experimentation that is pernicious._

So, there's a point about philosophy of science to be made here. If you test
one bronze alloy for antigravity, and then test a slightly different bronze
alloy for antigravity, and so on, finding all of them to fall when dropped,
how can you know when it's reasonable to stop testing bronze alloys for
antigravity? Presumably, you should eventually say "this idea has already been
tested," and then stop. However there will always be a new ratio of metals to
try: the only way to say "this has been tested" or "this hasn't" is to
establish enough of a theory to make predictions about the effect of gravity
on _every_ bronze alloy, and then trust it when it says it will not become
negative (at least, trust it enough to let it rule out potential experiments
from grant approval.) When we say, "a new arrangement of photons will still
conserve momentum," we are performing exactly the kind of interpolation from
other experiments involving photons in cavities that, previously, stopped us
from making more and more bronze bars in the search for antigravity.

~~~
danielbarla
Sure, but is that line of reasoning similar to the situation with the EMDrive?
I thought the interesting part was that there was an actual as-yet unexplained
result / measurement. So, going back to the bronze alloys, it's more like
"crazy person X has found a bronze alloy that almost seems like antigravity,
and it seems to break all fundamental laws of physics". Should we disregard,
or humour it look into it? It was always very likely to be some kind of error,
but it's a fundamentally less silly exercise.

~~~
crusso
_there was an actual as-yet unexplained result / measurement_

    
    
      1. "actual" isn't that actual if enough independent 
      scientists aren't duplicating it using scientifically 
      accepted testing procedures.
    
      2. "actual" isn't that actual when the quantity is down 
      at around noise level.
    

_crazy person X has found a bronze alloy that almost seems like antigravity_

You're using words like "almost seems" that just don't match up to the results
seen, especially considering the flawed testing methods used.

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njarboe
Poor title. It is sad to see academic descend into click-baitness. Even the
abstract does not tell you the key point of the paper. The most one gets from
the abstract is:

Our results show that the magnetic interaction from not sufficiently shielded
cables or thrusters are a major factor that needs to be taken into account for
proper µN thrust measurements for these type of devices.

Reading the paper one can finally get to what we want to know, "Do these
thrusters work?" The answer is no and/or can't tell yet.

Under the EMDrive section:

This clearly indicates that the “thrust” is not coming from the EMDrive but
from some electromagnetic interaction.

Under the Mach-Effect section:

This again indicates that there must be some electromagnetic interaction or
thermally induced center of mass shift that is masking any real thrust value.

Edit - I did not read the whole paper but skimmed for these descriptions of if
they found any real thrust signal.

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terravion
I think everyone that hopes for a bright future wishes the EM drive worked--an
Epstein Drive in our own time! Alas, wishes do not make it so...

~~~
roywiggins
Reactionless drives are even "worse" than Epstein drives, since they break
conservation of momentum entirely. Epstein drives just have wildly implausible
characteristics- while they might break all known laws of, say, material and
nuclear science, they don't break conservation laws since they require
reaction mass.

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ben_w
Given what appears on screen, the Epstein Drive doesn’t even have that
problem. It “only” acts like an electrostatic confinement fusion reactor with
a hole in the confinement, slight enough for only the fusion products to
escape, where the nozzle points.

(Edit footnote: only seen s1/2, anything surprising in s3 is unknown to me).

~~~
roywiggins
The "Eros incident" does imply that the aliens have an interesting
relationship with momentum, since ordinarily accelerating something that big
that fast would grind everything to a pulp.

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ggm
I want to believe the same way I suspend disbelief when I read S.F. -Its
temporally applied. Stop reading the S.F.? no time travel or FTL.

So my wishes aside, I feel like this is very tenuous, and is going to come
down to "better measurement isolated an effect causing this" more then "there
is now a tractable reactionless drive at scale for big things"

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dandare
I don't understand how the EMDrive came to be a serious topic.

First, someone proposed a design that violates both conservation of momentum
and conservation of energy, but that's cool because you know, fuck physics.
Then there was a hoax and yellow journalism and in the end, several
experiments failed to confirm/reproduce the effect, but that's cool because we
have this awesome theory we are trying to confirm, right?

By the way, I am looking for a team of physicists that will confirm my
revolutionary Tooth Fairy Drive(tm).

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Animats
_Testing of propellantless propulsion concepts requires a highly sophisticated
thrust balance that must be able to reliably detect very small thrust with a
resolution down to the nano-Newton range, block electromagnetic interactions
as much as possible and limit any balance-vacuum chamber wall interactions._

The thrust, if any, is so weak it's down in the noise. For a propulsion
system, that's a big problem. It's like cold fusion in that way.

~~~
Animats
Nano-Newtons. For comparison, the tiny rockets used for attitude control on
satellites have a thrust of about four Newtons. Falcon 9 booster, about
7,000,000 Newtons. This thing, if it works, maybe 0.00000001 Newton.

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rjplatte
The fact that no-one has conclusively disproven this yet gives me hope. My
desperate desire for this to be real has nothing to do with that hope
whatsoever.

I feel like, if this is real, it's one of those sci-fi MacGuffin technologies.
Literally changes everything.

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olliej
The tldr for emdrive: having verified that changing the direction of the
engine the thrust direction also changed, but when they attenuated the power
to just the drive component, which should have changed the thrust, but it did
not. Therefore the thrust being seen was not being produced by the drive
itself.

For the piezo one the predicted thrust was below the noise threshold in their
final tests (specifically below center of mass movements that were also - to
my reading - due to the control electronics)

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TangoTrotFox
I think it's reasonable to speculate that the air force is already carrying
out live tests. The reason for this is that NASA went through a substantial
amount of effort to trial and test the EM drive to their greatest ability, and
it came out on top with everything they could throw at it. And it's just been
a black out since then. That was about 1.5 years ago.

In the interim the air force has sent up the classified X-37 [1]. They've
stated it's mission purpose is _" risk reduction, experimentation, and
operational concept development for reusable space vehicle technologies, in
support of long-term developmental space objectives"_. That's certainly a
horoscope style description, but at the same time it does seem to fit quite
well for live testing of propellantless drives, even if not as a primary
mission.

Furthermore, if the EM-drive did work, it would have a beyond revolutionary
impact on everything and so it would not be surprising that it would end up
getting classified after passing the initial slew of tests thrown at it.

[1] -
[https://en.wikipedia.org/wiki/Boeing_X-37](https://en.wikipedia.org/wiki/Boeing_X-37)

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JTbane
I'm still convinced EMDrive is the latest cold fusion, perpetual motion,
panacea, whatever they are calling it these days.

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lutorm
Since you can launch cubesats for comparatively little money these days,
someone should actually launch one.

~~~
vertexFarm
Unfortunately it would have to be a little further from Earth's magnetosphere
to get a good test. Cubesats are kind of atmosphere skimmers.

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c-smile
Damn, the picture "killing of glorious idea by disgusting facts" again.

Sigh, will wait for the next "deformator of space/time curvature" device for
the human race to reach stars ...

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jimmcslim
Assuming the effect of the EMDrive were real and practically exploitable, what
does that say about the Fermi paradox?

~~~
andygates
As a sci-fi writing prompt? "We're first," with all the disappointment and
responsibility that implies.

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tomatotomato37
I always doubted the reactionless drive aspect of this, but has anymore
research gone into the apparent spacetime warping effect that one NASA group
discovered? Even if it can't do anything more than disort light more
effectively than lots of magnetism doesn't make it useless

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madengr
There goes my hunch that it was rectified DC currents in the cavity.

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andrepd
In other news, prepetual motion machine found not to work.

~~~
inteleng
No. Nothing was found (nailed down, proven) here except that error bounds need
to be improved.

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jcims
Edit: Title has been changed, leaving this for posterity.

Apologies for formatting, but the title doesn’t match the conclusion of the
paper.

“First measurement campaigns were carried out with both thruster models
reaching thrust/thrust-to- power levels comparable to claimed values. However,
we found that e.g. magnetic interaction from twisted-pair cables and
amplifiers with the Earth’s magnetic field can be a significant error source
for EMDrives.”

There was no experimental validation of this, just speculation based on their
observations. They propose a simple fix, run the experiment in a magnetically
shielded environment. They suggest Mu metal for maximum shielding, which would
be good, but I’m a little skeptical that the vacuum vessels used in previous
tests would have allowed a substantial flux of earths magnetic field through
the environment. Using my phone's basic magnetometer, I get an order of
magnitude reduction in field strength by placing it ~8" inside my oven and
leaving the door open.

In any event they are probably on to something here. Certainly a more
plausible explanation than any of the alternatives.

~~~
akhatri_aus
There was kind of. When they turn the EMDrive on its side the thrust doesn't
come from the cone anymore it comes from an angle meaning that the angle at
which the EMDrive/cone is placed has no relevance to the thrust's vector.

Imagine turning a rocket from horizontal to vertical and finding it still goes
up, despite the exhaust from the engine going sideways.

~~~
bufferoverflow
That's not what Fig 13 says.

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stale2002
I am surprised that nobody has yet to attempt the "simple" solution for
testing something like this.

The simple solution being to put it in space, turn it on, and see if it
'stays' in space.

The claimed amount of thrust is significant enough that it will either
obviously succeed or fail if you actually put it in space.

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sushisource
That's not "simple". It's very, very, very expensive to put things in space.
Trying to figure it out on the ground first makes sense for a number of
reasons.

~~~
aeternus
They should have asked Elon to toss it in the back of his roadster.

~~~
vertexFarm
Damn it, that would have been a great idea. We could have gotten rid of this
silly concept for good. Musk, it's time to launch another car!

~~~
nasasucks
Well, to be fair, Elon _did_ offer a free payload to NASA but they were too
old and grumpy to accept the generous offer so Tesla nailed a car to it at the
last minute instead.

