Re: Public Lecture by Roger Shawyer [Archive]

Greg Egan

Nov22-06, 05:00 AM

In article <20061120152835012-0500@newsread.grc.nasa.gov>, Marc Millis
<marc.g.millis@nasa.gov> wrote:

> Thanks for asking for the clarification.
>
> They way that I understood it, EM bounces off of angled walls and
> eventually exists the wider end. When it exits the wider end, there
> will be thrust equivalent to a photon rocket, which ain't much.
>
> When I took the brief moments to look at this before, there were
> actually more than one explanations. One implied that no radiation left
> the device, while the other stated that it did, but with an exit
> velocity much slower than c, and that this would lead to a greater
> thrust (using F=p/c). The lower c argument ain't right either (geometry
> wrong), but at least that version did have radiation exiting the device.
>
> What I really want to see is how they inferred measurable thrust from
> their set up. I am still surprised that this one gets as much attention
> as it does.
>
> Marc

Thanks very much for your reply.

Nothing covered in the New Scientist article canvassed the possibility of
radiation leaving the cavity, though who knows what variations Shawyer
has put to various people over the years. He has an old patent
application for something with cylindrical (non-tapered) walls and a
cone-shaped piece of dielectric at one end, but this year's model, as
described in New Scientist, and in:

http://www.newscientist.com/data/images/ns/av/shawyertheory.pdf

is for a closed, truncated conical cavity (with a small dielectric
cylinder attached at the small end).

If this isn't too intrusive, do you mind sketching briefly what contact
you've had with Shawyer and/or New Scientist? I'd been assuming that you
first heard of this proposal when New Scientist were writing the article
and phoning around for comments, but from what you've said it sounds as
if Shawyer's proposal came to you long before that, in some kind of
submission to NASA. It'd be interesting to know the context and outcome
of that submission.

It would also be interesting to know if New Scientist contacted you
directly at all, what they asked, and whether they described your
opinions fairly and accurately. In the context of the article, the clear
implication is that you're agreeing with the only hypothesis presented in
the article, which is that the total force on the walls of a closed
asymmetric cavity is non-zero (albeit with reservations about the
magnitude of the thrust). If you were actually conceding a completely
different point about a completely different design -- an open cavity
acting as a photon rocket -- then either there was a serious
misunderstanding on the journalist's part, or you've been seriously
misrepresented.

I know you've pointed out, quite rightly, that this is not worth the
attention it's getting, but what I'm trying to unravel is not so much the
unexceptional pathology of the crackpot science itself as the somewhat
unusual pathology of the way it's been covered. New Scientist isn't
alone -- a few engineering magazines have given it equally credulous
beat-ups -- but the widely syndicated New Scientist story has given it an
exposure and "credibility" far beyond the usual junk-science noise level,
which is why I think it's worth trying to pin down the details of how
such a misguided and ill-informed piece of science journalism came to be
written and published.

As for how they get measurable thrusts, I'd put my money on thermally
induced air flows. If you take a look at:

http://www.ind-tech.com/vertical_thrust_tests.jpg

you'll see that the force builds up over several seconds after the power
is switched on, which seems indicative of something heating up.

Marc Millis

Nov27-06, 05:00 AM

In <20061122063407.0E62F4C3F9@mail.netspace.net.au> Greg Egan wrote:
-snip-
> Thanks very much for your reply.
-snip-
> If this isn't too intrusive, do you mind sketching briefly what
> contact you've had with Shawyer and/or New Scientist? I'd been
> assuming that you first heard of this proposal when New Scientist
> were writing the article and phoning around for comments, but from
> what you've said it sounds as if Shawyer's proposal came to you long
> before that, in some kind of submission to NASA. It'd be interesting
> to know the context and outcome of that submission.
>
> It would also be interesting to know if New Scientist contacted you
> directly at all, what they asked, and whether they described your
> opinions fairly and accurately. In the context of the article, the
> clear implication is that you're agreeing with the only hypothesis
> presented in the article, which is that the total force on the walls
> of a closed asymmetric cavity is non-zero (albeit with reservations
> about the magnitude of the thrust). If you were actually conceding a
> completely different point about a completely different design -- an
> open cavity acting as a photon rocket -- then either there was a
> serious misunderstanding on the journalist's part, or you've been
> seriously misrepresented.
>
> I know you've pointed out, quite rightly, that this is not worth the
> attention it's getting, but what I'm trying to unravel is not so much
> the unexceptional pathology of the crackpot science itself as the
> somewhat unusual pathology of the way it's been covered. New
> Scientist isn't alone -- a few engineering magazines have given it
> equally credulous beat-ups -- but the widely syndicated New Scientist
> story has given it an exposure and "credibility" far beyond the usual
> junk-science noise level, which is why I think it's worth trying to
> pin down the details of how such a misguided and ill-informed piece
> of science journalism came to be written and published.
-snip-

I agree that the subject of how our community is treating this warrants
some dissection and reflection, so I've taken the time to dig out some
details of the chain of events, plus add some personal commentary.

From my point of view, the attention given to Shawyer's claim is
disproportionately high, and it is inconsistent with my prior
experiences with the Press. In general over the years, I've been
impressed with how the Press has covered "Breakthrough Propulsion
Physics." This topic is one that could easily be sensationalized or
vilified, which is seldom done. I consider Shawyer's coverage as
sensationalistic. Most prior articles on BPP draw a healthy contrast
between "these things might be impossible" and "perhaps there are some
useful things lurking amongst unfinished physics." Personally, I
struggle to find the credible foundations that take the risk of looking
beyond what is safely familiar. It is a challenging balancing act. If
any of you are interested in the management methods that I've employed
on this topic, please read:

<http://gltrs.grc.nasa.gov/reports/2004/TM-2004-213406.pdf>

Now, here are specifics regarding the Shawyer events:

A colleague of mine first drew my attention in July 2005 to this
specific paper and asked me and several others for feedback:
[R. Shawyer, "The Development of a Microwave Engine for Spacecraft
Propulsion," Space Chronicles JBIS, Vol. 58, pp. 26-31]

It took me until August 2005 to get a copy and scan it, and here is an
excerpt from my reply to my colleague:

---------begin old email excerpt-------- I just received my copy of the
cited report and scanned it quickly.

Here are my first-cut observations:
- One of the critical assertions is
that he is achieving greater than normal radiation pressure because it
has effectively reduced the speed of light where the momentum is
imparted (6th paragraph).
- The device has asymmetric internal walls for
its wave-guide, so the net interior forces will be unbalanced (7th
paragraph) [okay]
- Another critical assertion is that the momentum
imparted against the wall inside the wave-guide is equivalent to as if
they were being imparted from the outside. (8th paragraph). This, to me,

seems the most questionable for now, especially in combination with the
6th paragraph.
I did not yet run through the equations and I cannot
make out any details of the photos from the copy our library obtained.
The other critical assertions is that his tests match his predictions.

That's all for now. Has anyone else taken a crack at this yet?
----------
end of old email excerpt-------

It wasn't until November 2005 that Ben Crystall, of New Scientist,
contacted me by email. Here is an excerpt from my reply that I sent a
day later:

---------begin old email excerpt-------- Ben,
I'm not sure how much
time I can devote to this before next week, so I will say what I can
right now about Roger Shawyer claims. I've Cc'd our public affairs
office on this as well as some other colleagues who raised questions
about this particular work. I am not sure if any of them have anything
to add.
I recall quickly scanning the following publication from
Shawyer: R. Shawyer, "The Development of a Microwave Engine for
Spacecraft Propulsion," Space Chronicles JBIS, Vol. 58, pp 26-31.
From
which I had these observations:
1. One of the critical assertions is
that he is achieving greater than normal radiation pressure because it
has effectively reduced the speed of light at the location where the
momentum is imparted (6th paragraph).
2. The device has asymmetric
internal walls for its wave-guide, so the net interior forces will be
unbalanced (7th paragraph) [I'm okay with that as there is a net
direction for the radiation].
3. Another critical assertion is that the
momentum imparted against the wall *inside* the wave-guide is equivalent
to as if they were being imparted from the outside. (8th paragraph).
This, to me, seems the most uncertain, especially in combination with
the critical assertion that he is achieving greater than normal
radiation pressure because it has effectively reduced the speed of light
at the location where the momentum is imparted (6th paragraph). The
speed of light outside of the device would be the normal vacuum value.

4. There is also the issue that, even if items 1 & 3 turn out to be
valid, that the net force could sum to a normal photon rocket when
including the final exit of the microwaves from the device, when they
enter normal light-speed and normal photon radiation pressure regimes.

5. Finally, if someone else is paying for rigorous tests of these claims,

I'm content to wait to see how those tests turn out before devoting any
more time at the moment to assess the claims. This is all I can say
from a quick scan of the work. I did not run through his equations nor
could I make out any details of the photos from the copy our library
obtained.

Marc
----------end of old email excerpt-------

Eventually, and I cannot find my notes about this, I was interviewed
over the phone by someone at New Scientist. Their article came out much
later, and the short quote attributed to me (and that you asked about)
was accurate to what I said over the phone. During the interview, I did
not realize that there was a version of Shawyer that claimed that no
radiation left the device. When I gave my comments, it was about the
version that I had reviewed and which I interpreted as radiation being
emitted. I have not gone back to see if I erred in my interpretation (
which if I did it was probably due to assuming this as a necessary
condition for thrust). I do not recall if the New Scientist reporter
raised the issue of 'no-radiation' or not. We could have both been in
error when not realizing that key ambiguity.

I learned later about the 'no-radiation version', but do not recall when
or what it was that I read. And, I do not feel it's worth the trouble to
look it up in more detail. I just figured that this whole thing would
fade away into oblivion, or that convincing experimental data would
eventually emerge. It is the experimental findings that I pay more
attention to, in general.

IF (big if) substantial experimental data did emerge, I feel it would
then merit my time to take a closer look. There would be value in
either the case of an error or a discovery. If errant, it would be
useful to draw attention to how one could easily be led astray by
experimental artifacts. From personal experience, I know it is
difficult to sort out the causes of experimental artifacts. Actually,
this kind of work is fun. On the other hand, on the slim chance that
there was a genuine new effect discovered, I would want to see that from
the experiment's point of view, not its theory. If we stumble upon some
new physics effect, I strongly feel that we stand more to learn by
dissecting the experiment than to assume the 'theory' that was contrived
for it is correct. I put more faith in empirical data than in impulsive
interpretations thereof.

NEXT... here is the strategy I've been playing in the meantime. I'm
disclosing this here in response to your concern (which I share) about
how our community is dealing with such claims.

Given this anomalous attention, I'm taking the tactic of just letting it
run its course. To those who know the topic of "breakthrough propulsion
physics" well, they know that this idea is not a top contender by any
stretch, so anyone who is drawn to it is probably not a top contender
for being a collaborator. In a sense, I've been using this odd event as
a filter for collaborators. Those that got excited and wanted to dive
into it more detail, ended up on my low-priority list.

Subsequently, I keep being asked about it from various sources, and my
replies have been short and to the effect of: "Doesn't look right, but
show me the experimental data and methods." This is pretty much a
standard reply I send on any of the numerous submissions that come my
way. Given how many different things that I've seen that are on par
with the Shawyer claim (and others that are clearly based on firmer
ground), I am still amazed that Shawyer's is getting this much attention.

As much as there is historical precedent for prematurely dismissing new
discoveries as errors (which the crackpots love to cite), this tendency
is a natural transient response that fades if the latest claim passes
the tests for being genuine. Although our system is not perfect for
quickly and accurately screening things, it seems to work in the long
run. There is also historical precedent for folks putting stock into
belief systems that impartial data does not support. That, sigh, seems
to linger.

There is a difficult trade-off when trying to decide how much attention
to give emergent claims, and statistically is is more reputable just to
dismiss them all. History has shown, however, that being so pedantic
does not sustain intellectual leadership. We are occasionally surprised
by breakthroughs. Breakthroughs happen. But even the genuine
breakthroughs sound crazy at first, so the real challenge is how to sort
them out in a labor-efficient manner. As I stated before, if you are
interested, I documented the techniques that I use for facing this
challenge (URL cited earlier).

When it comes to the Shawyer claims; I am very pessimistic, but I will
reconsider if (and only if) there is credible experimental evidence. In
the meanwhile I am trying to extract value from the events surrounding
this claim, by using it as a filter for the players involved.

It is difficult to be credible and visionary at the same time. It is
easy to be only credible or only visionary. The former is at least
reputable in the near term, and the latter is at least entertaining.
Being a pioneer, however, requires being both, plus having the impartial
rigor to let the chips fall where may, based on how nature dictates,
regardless of where we expected or wanted them to fall.

Marc