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#2280 by rfmwguy on 27 Jan, 2016 03:20
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I think most of us are trying to look at the emdrive from the perspective of fundamental physics. Everything in this realm is pretty well buttoned up with the exception of gravity and "antigravity", what most call dark energy and/or matter. The expansion of the universe cannot be fully explained nor agreed upon.
Therein lies openings for new physics, as a couple of key fundamentals have eluded us. Having no theory yet, I can only believe these are the the areas where the emdrive effect might reside. I cannot see fundamental physics working to explain it.
Herein lies the basis for much of the emotion about the emdrive. Does one believe new physics is even possible? IMO you would almost have to considering what we observe and cannot yet explain...gravity and the expanding universe. -
#2281 by SteveD on 27 Jan, 2016 03:51
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...
Again, because a Photonic Laser Thruster, (unlike what is proposed by EM Drive proponents) implies not one spaceship but two (or more than two), and the other spaceship(s) (the "resource vehicle(s)") have to move in the opposite direction to the "mission vehicle" as the result of the photonic momentum.
Again, how does this not apply to a Photonic Laser Thruster?
Actually, to go far, the proponents of the photonic laser thruster are proposing a very costly and complicated infrastructure of "resource vehicles" that are stationed, ahead of time, at different future positions in the path of the photonic laser thruster "mission vehicle", in order for the photonic laser thruster "mission vehicle" to be able to go far...
To correctly apply conservation of energy and conservation of momentum, to the photonic laser thruster you have to consider all the vehicles (at least two vehicles) involved in the photonic laser thruster concept (*).
________
(*) Similarly Prof. Woodward in his Mach Effect principle claims that in effect all masses in the Universe are responsible for the Woodward effect, so all masses involved are affected (to a larger or smaller effect)
"the local inertia frame is completely determined by the dynamic fields in the whole Universe."
In stark contrast, Shawyer claims that the EM Drive "propulsion" can be completely explained by a completely closed cavity by itself, without recurring to any external field, just based on Maxwell's equations and Special Relativity, as a completely closed system. (Of course such a theory as Shaywer's runs contrary to conservation of energy/momentum).
Clearly, a photonic laser thruster lacks the conservation of momentum problems of an EMDrive. We're talking about conservation of energy here. 2NW/C seems to imply constant acceleration from constant power. KE=1/2mv^2 implies a point where increase in KE > W for a given period of time. A series of service vehicles means only the propelled capsule has this potential problem. Still, at some point, it seems like something interesting has to happen to keep the energy books balanced. I can't help but thinking an understanding of how a PLT does not break things might provide insight into the EMDrive effect. I'm reminded of the paper from several threads ago that suggested that warped space time might, in the right circumstances, combine with quantum effects to act as a mirror. If applicable to the EMDrive, that would suggest an answer to the CoM issue very similar to the PLT, what about CoE though? -
#2282 by SteveD on 27 Jan, 2016 04:05
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I think most of us are trying to look at the emdrive from the perspective of fundamental physics. Everything in this realm is pretty well buttoned up with the exception of gravity and "antigravity", what most call dark energy and/or matter. The expansion of the universe cannot be fully explained nor agreed upon.
Therein lies openings for new physics, as a couple of key fundamentals have eluded us. Having no theory yet, I can only believe these are the the areas where the emdrive effect might reside. I cannot see fundamental physics working to explain it.
Herein lies the basis for much of the emotion about the emdrive. Does one believe new physics is even possible? IMO you would almost have to considering what we observe and cannot yet explain...gravity and the expanding universe.
I wonder if part of the divide over this is that engineers are accustomed to equipment occasionally operating in an undocumented manner while physicists rarely have an unexpected result other than a null. -
#2283 by spupeng7 on 27 Jan, 2016 04:43
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A thankyou to Dr Rodal for the excellent reply to my damping chat question :-)
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#2284 by Chrochne on 27 Jan, 2016 07:03
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Very interesting Optical/Laser EmDrive from the Monomorphic at the reddit forum
https://www.reddit.com/r/EmDrive/comments/42uzo7/opticallaser_emdrive_revealed/
In his words "I hope to post some videos in the next few days, along with some of the other stuff I have been working on."
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#2285 by Tellmeagain on 27 Jan, 2016 08:27
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...
Again, because a Photonic Laser Thruster, (unlike what is proposed by EM Drive proponents) implies not one spaceship but two (or more than two), and the other spaceship(s) (the "resource vehicle(s)") have to move in the opposite direction to the "mission vehicle" as the result of the photonic momentum.
Again, how does this not apply to a Photonic Laser Thruster?
Actually, to go far, the proponents of the photonic laser thruster are proposing a very costly and complicated infrastructure of "resource vehicles" that are stationed, ahead of time, at different future positions in the path of the photonic laser thruster "mission vehicle", in order for the photonic laser thruster "mission vehicle" to be able to go far...
To correctly apply conservation of energy and conservation of momentum, to the photonic laser thruster you have to consider all the vehicles (at least two vehicles) involved in the photonic laser thruster concept (*).
________
(*) Similarly Prof. Woodward in his Mach Effect principle claims that in effect all masses in the Universe are responsible for the Woodward effect, so all masses involved are affected (to a larger or smaller effect)
"the local inertia frame is completely determined by the dynamic fields in the whole Universe."
In stark contrast, Shawyer claims that the EM Drive "propulsion" can be completely explained by a completely closed cavity by itself, without recurring to any external field, just based on Maxwell's equations and Special Relativity, as a completely closed system. (Of course such a theory as Shaywer's runs contrary to conservation of energy/momentum).
Clearly, a photonic laser thruster lacks the conservation of momentum problems of an EMDrive. We're talking about conservation of energy here. 2NW/C seems to imply constant acceleration from constant power. KE=1/2mv^2 implies a point where increase in KE > W for a given period of time. A series of service vehicles means only the propelled capsule has this potential problem. Still, at some point, it seems like something interesting has to happen to keep the energy books balanced. I can't help but thinking an understanding of how a PLT does not break things might provide insight into the EMDrive effect. I'm reminded of the paper from several threads ago that suggested that warped space time might, in the right circumstances, combine with quantum effects to act as a mirror. If applicable to the EMDrive, that would suggest an answer to the CoM issue very similar to the PLT, what about CoE though?
this is the (right) answer to your CoE question, http://forum.nasaspaceflight.com/index.php?topic=39004.msg1483616#msg1483616 -
#2286 by frobnicat on 27 Jan, 2016 10:42
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I was thinking about the topic of the light being reflected in the cavity or Q. As light information doesn't angularly rotate when the frustum is rotated then any modes inside will have to be attenuated before a new mode in the new frustum angular orientation can form. There should be some resistance to angular rotation of a cavity. As a result rotating a resonating cavity should decrease the Q, I would imagine.
.../...
One thing I learned while following the advanced concepts forums (before I got lured into EM drive craze) is the importance of both imagination and of being able to derive at least plausible order of magnitude estimation in support of such imaginative ideas.
While the EM radiations (photons) are relativistic by nature, it is known (both theoretically and experimentally) that the "inertial effects" (position of center of mass, conservation of momentum, recoils...) as measured on subrelativistic (wrt. to deltaVs involved) massive objects interacting with such radiations can be quantitatively correctly derived within Newtonian mechanics + "relativistic mass" of radiations.
While the concept of "relativistic mass" appears to have fallen in disgrace for modern serious physics teaching (see the above link at wikipedia) as it is not an intrinsic invariant property (like rest mass) but only a covariant value (like kinetic energy), it is convenient and correct for the less subtle arguments here at hand. For instance a photon of energy E will have a relativistic mass of mrel=E/c˛, when it leaves the nozzle of a photon rocket it carries away a momentum p equal to its speed c times relativistic mass : p=mrel×c=E/c. A thrust F (propulsive force) is the time derivative of such induced recoils on the rocket (N=(kg.m/s)/s) and power needed to sustain the flow of leaving photons is the time derivative of energy for each one (W=J/s) => d(p=E/c)/dt => F=P/c. We see that this useful tool of "relativistic mass" gives the correct thrust for a photon rocket, without having to go through h/λ, just by treating photons as if it was a Newtonian ejected flow of particles of rest mass E/c˛ at velocity c (relative to rocket).
So. The total EM energy inside a powered on 1kW 2.45GHz frustum is on the order of E=.01 J (10µs worth of 1kW, give or take depending on Q). The corresponding relativistic mass mrel=E/c˛≈10-19kg
This is the change in "apparent inertia" between a powered frustum and an un-powered frustum. This is a hundred thousandth of the relativistic mass of heat alone that is added during 1s of power (as the relativistic mass of thermal agitation). That a hot brick is (a little bit) heavier than the same brick colder is pretty uncontroversial (even if I think this has never been measured experimentally) : here is a citation of grad student in theoretical physics. I feel linking to a post on madsci.org is perfectly relevant here...
So in the end, no, the energy content involved will not make any measurable difference on apparent inertia, be it translational nor rotational inertia, because of the vanishingly small instantaneous mrel implied. Note that sending away (losing forever) at c and in a collimated direction such minuscule mrel but again and again 100000 times a second would indeed give a small but measurable thrust of 3.33µN (photon thrust).
As for the effect of Q, I ask : has anyone ever noticed a gravity or acceleration induced significant (measurable) change of Q, or of resonant frequency, or even the slightest phase shift, with radio frequency excited cavities, ever ? I'm not talking here of change in geometry of cavity deforming under such acceleration, but of direct acceleration effects on the resonant wave at the scales (λ and sizes) typically involved with RF cavities. I know there are optical gyroscope, but this is not same λ. Sagnac effect on microwaves, really ? I'd like to see some rough simple order of magnitude estimation to believe it's measurable at all (before it's supposed to act as mechanical actuator !)
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#2287 by RERT on 27 Jan, 2016 10:48
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Folks - a few points on recent posts.
WolfOfWallStreet: Sorry I misled you on the 1 second RF pulse, though I think my comment on heating being small in TT's test still applies, assuming 'a few seconds' is small enough. This is what he said on Reddit:QuoteRf is applied at min 80mW to manually tune freq for best VSWR. Then max power is applied for a few seconds.
Thrust change is immediate On and Off the Rf. No delay I can determine.
No evidence of significant thermal buoyancy.
Maybe due to very short Rf on time. Do wait 5 minutes between measurements and do low power tune just before every max power test run.
A_M_Swallow: nobody has challenged your calculations, and I find them very exciting! Seems like a one tonne satellite in a similar orbit would need 200*(128/420)*(189.9/(365.25/2)) =~ 63 watts of power to keep station with daylight only thrust. That's a solar panel 19" on a side at 20% efficiency.
Many re: Conservation of Energy.
I've said this before more obliquely, but I'll have another go. A photon rocket seems like a propellant-less thruster if you don't know that the photons carry momentum. The EMDrive is a propellant-less thruster because we don't know where the momentum is going. As long as it's 'New Physics', there is no argument that it is a perpetual motion machine, because we don't have the slightest clue how to work out the energy balance.
Deducing that it seems to be a perpetual motion machine just reinforces the state of our ignorance as to how it works (assuming it does!). That's a fair thing to do, but does nothing of itself to negate experimental results.
Many re: Peer Review & Established Theories
Dr.Rodal has pointed out that we've recently had reports published of signals moving faster than light. These go against current physical laws, so it seems that is no bar to publication. If there is no room for papers which say 'We measured this, we know it shouldn't be so, but it is. We have no idea how it works.' then we might as well put the Pope back in charge of scientific facts. What I can speculate might hold up peer-review is promoting an explanatory theory which is obviously wrong or full of holes.
All IMHO, and thank you for getting this far.
R.
[Edited to fix format error and vocab.] -
#2288 by Rodal on 27 Jan, 2016 11:43
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....
Yes, as I said, there is no problem with writing "'We measured this acceleration or this force" and there are several journals that will accept that for publication, particularly if "this anomalous force" is satisfactorily shown in the paper not to be explained by conventional forces (thermal forces, ambient electromagnetic fields, etc.).
Many re: Peer Review & Established Theories
Dr.Rodal has pointed out that we've recently had reports published of signals moving faster than light. These go against current physical laws, so it seems that is no bar to publication. If there is no room for papers which say 'We measured this, we know it shouldn't be so, but it is. We have no idea how it works.' then we might as well put the Pope back in charge of scientific facts. What I can speculate might hold up peer-review is promoting an explanatory theory which is obviously wrong or full of holes.
All IMHO, and thank you for getting this far.
R.
[Edited to fix format error and vocab.]
A couple of concrete examples.
There will be problems though, with peer review if for example the paper calls a test performed with a Cavendish-type pendulum, a teeter-totter balance, a torque pendulum, a digital scale, or similar such device, a flight-test, because a peer-reviewer must raise the obvious fact that none of those measurements constitutes flying, since when flying an object is free of mechanical constraints (free mechanical boundary conditions) and in those measurements the object is mechanically constrained. Then the author either edits her paper to eliminate the incorrect statement of "fligh test" or better comes up with a coherent explanation as to why such tests constitute a flight test. If this is not addressed to the satisfaction of the peer reviewer, then the paper does not make it through peer review.
Goddard performed flight tests with small chemical rockets. Ted Taylor and Freeman Dyson's Project Orion performed flight tests with explosives. No EM Drive experiment performed up to now, to my knowledge, constitutes a flight test.
If the author of the paper calls the force measurement "thrust" (while in a contradictory manner simultaneously claims that no mass is being ejected) instead of "anomalous force" and further proceeds to propose an equation where this thrust force/Power > 1/c can be used to go to Pluto as a propellant-less propulsion in a relative short time (compared to other space propulsion alternatives) without relying on any external fields or any mass ejection, then the author may be challenged by the peer-reviewer (if the peer reviewer notices the free-energy aspect of what is being claimed) on the fact that this claim runs contrary to conservation of energy. The author will be asked by the peer-reviewer to satisfactorily address the free-energy and perpetual motion aspects of her claim. Then the author, to get the paper published in that journal can a) withdraw the above-stated claims of space propulsion or b) provide an answer that satisfies the peer-reviewer concerns. Providing examples of a photon rocket or of a photonic laser thruster are not satisfactory answers (as previously explained).
The author of the paper may be challenged by a peer-reviewer (if the peer reviewer has expertise on energy conservation issues) on the fact that that an anomalous force measured for a duration of a few seconds in a mechanically constrained experiment is by no means a valid basis to grossly extrapolate a several weeks (or months) long propellant-less spaceflight with a force/power claimed to exceed by orders of magnitude the efficiency of a photon rocket. -
#2289 by Rodal on 27 Jan, 2016 12:49
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...
There are, and have been many military, private and research microwave resonance devices in space experiencing centripetal acceleration.
As for the effect of Q, I ask : has anyone ever noticed a gravity or acceleration induced significant (measurable) change of Q, or of resonant frequency, or even the slightest phase shift, with radio frequency excited cavities, ever ? I'm not talking here of change in geometry of cavity deforming under such acceleration, but of direct acceleration effects on the resonant wave at the scales (λ and sizes) typically involved with RF cavities. I know there are optical gyroscope, but this is not same λ. Sagnac effect on microwaves, really ? I'd like to see some rough simple order of magnitude estimation to believe it's measurable at all (before it's supposed to act as mechanical actuator !)
Early on, it was noticed that resonant cavities and resonance of open waveguides in space displayed changes in frequency and changes in Q. This was investigated and explained both in the US and in the USSR as being due to the same multipactor effect experienced earlier with particle accelerators and not due to changes in acceleration, speed or position of the space vehicles. Since then, the design of such resonant RF devices has to be done taking into account the multipactor effect.
In space-borne equipment the multipactor effect is a severe problem that can generate RF noise, alter impedance, generate heat and cause hardware damage.
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#2290 by Willem Staal on 27 Jan, 2016 13:03
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An idea, the original cavity magnetron made by Randall and Booth before the second world war had 6 cavities alternating to achieve maximum power. If you try multiple small cavities (depending on the diameter of the small end of the frustrum and a cycling wire arrangement and place the rf transmitter on top of the frustrum you might boost the result. the funnel will elongate the effect.
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#2291 by SeeShells on 27 Jan, 2016 13:20
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Spot on Dr. Rodal.....
Yes, as I said, there is no problem with writing "'We measured this acceleration or this force" and there are several journals that will accept that for publication, particularly if "this anomalous force" is satisfactorily shown in the paper not to be explained by conventional forces (thermal forces, ambient electromagnetic fields, etc.).
Many re: Peer Review & Established Theories
Dr.Rodal has pointed out that we've recently had reports published of signals moving faster than light. These go against current physical laws, so it seems that is no bar to publication. If there is no room for papers which say 'We measured this, we know it shouldn't be so, but it is. We have no idea how it works.' then we might as well put the Pope back in charge of scientific facts. What I can speculate might hold up peer-review is promoting an explanatory theory which is obviously wrong or full of holes.
All IMHO, and thank you for getting this far.
R.
[Edited to fix format error and vocab.]
A couple of concrete examples.
There will be problems though, with peer review if for example the paper calls a test performed with a Cavendish-type pendulum, a teeter-totter balance, a torque pendulum, a digital scale, or similar such device, a flight-test, because a peer-reviewer must raise the obvious fact that none of those measurements constitutes flying, since when flying an object is free of mechanical constraints (free mechanical boundary conditions) and in those measurements the object is mechanically constrained. Then the author either edits her paper to eliminate the incorrect statement of "fligh test" or better comes up with a coherent explanation as to why such tests constitute a flight test. If this is not addressed to the satisfaction of the peer reviewer, then the paper does not make it through peer review.
Goddard performed flight tests with small chemical rockets. Ted Taylor and Freeman Dyson's Project Orion performed flight tests with explosives. No EM Drive experiment performed up to now, to my knowledge, constitutes a flight test.
If the author of the paper calls the force measurement "thrust" (while in a contradictory manner simultaneously claims that no mass is being ejected) instead of "anomalous force" and further proceeds to propose an equation where this thrust force/Power > 1/c can be used to go to Pluto as a propellant-less propulsion in a relative short time (compared to other space propulsion alternatives) without relying on any external fields or any mass ejection, then the author may be challenged by the peer-reviewer (if the peer reviewer notices the free-energy aspect of what is being claimed) on the fact that this claim runs contrary to conservation of energy. The author will be asked by the peer-reviewer to satisfactorily address the free-energy and perpetual motion aspects of her claim. Then the author, to get the paper published in that journal can a) withdraw the above-stated claims of space propulsion or b) provide an answer that satisfies the peer-reviewer concerns. Providing examples of a photon rocket or of a photonic laser thruster are not satisfactory answers (as previously explained).
The author of the paper may be challenged by a peer-reviewer (if the peer reviewer has expertise on energy conservation issues) on the fact that that an anomalous force measured for a duration of a few seconds in a mechanically constrained experiment is by no means a valid basis to grossly extrapolate a several weeks (or months) long propellant-less spaceflight with a force/power claimed to exceed by orders of magnitude the efficiency of a photon rocket.
This is the reason for my DUT and cantilever teeter todder flucrum beam to test not only force generation with the digital scales but acceleration and they might not be the same in the EMDrive. Newton's second law needs to be verified in the same test bed as the force.
F = m * a
If I have 5 kilograms being pushed by .001N this will give me a positional acceleration of .0002meter/second^2 or 72 cm over 60 seconds. That would be a beam deflection of
72mm or just under 3 inches. That is well within my test bed measurement using the beam laser. The thermally compensating frustum with the magnetron source heat away from the frustum will allow it to run for over 10 minutes at a time if need be.
Shell
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#2292 by Rodal on 27 Jan, 2016 13:54
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An idea, the original cavity magnetron made by Randall and Booth before the second world war had 6 cavities alternating to achieve maximum power. If you try multiple small cavities (depending on the diameter of the small end of the frustrum and a cycling wire arrangement and place the rf transmitter on top of the frustrum you might boost the result. the funnel will elongate the effect.
This idea sounds similar to the ideas that Fetta had for the Cannae drive (see: http://www.google.com/patents/US20140013724 ) (remember that NASA ( http://ntrs.nasa.gov/search.jsp?R=20140006052 ) tested Fetta's ideas and found them to have a null effect for NASA's tests, yes granted that Fetta's slots are not identical to your surface re-entries, but they are small features in the circumferential direction in both cases compared to the mode shapes that have been tested up to now in EM Drives: TE012 -constant in the circumferential direction-and TM212 -quadrupole in the circumferential direction- for example).
From this drawing,
it looks to me that for this concept to make a difference you would need to either:
a) excite the cavity of dimensions similar to NASA, Shawyer and Yang at a natural frequency much higher than 2.45 GHz, so that a high mode shape with high m (TEmnp or TMmnp) would be excited.
or
b) excite a cavity with dimensions much smaller than the one used by NASA, Shawyer and Yang at ~2.45GHz so that a high mode shape with high m (TEmnp or TMmnp) would be excited,
from your drawing, it looks like 15/2, m= ~8 would be needed, looking like a "whispering gallery mode shape"
either way, it looks like the resulting Q may be significantly lower with your idea because your idea increases the surface losses, by increasing the surface/volume ratio (*), with all those re-entries, which according to the theories of Shawyer, McCulloch and Notsosureofit would be detrimental to the anomalous force those theories predict.
(*) The same way that the length of a coastline can be increased as compared to a smooth curve -
#2293 by rfmwguy on 27 Jan, 2016 14:07
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I agree with this. Even engineers have their moments. I saw this many times, a filter tech tuning a filter meets with an Engineer who says the math is there and the filter should tune...the tech says no. They go out to the Network Analyzer and sure enough, it wasn't math that's the problem, it was unexpected electromechanical properties of the enclosure, carrier, connectors, pins, proximity, real-life Qs, you name it. Often, these were one-off events not worthy of design program updates...some helped tweaked the software to make better real-world filters. For those who have never worked in this type of environment, it can be quite entertaining...I think most of us are trying to look at the emdrive from the perspective of fundamental physics. Everything in this realm is pretty well buttoned up with the exception of gravity and "antigravity", what most call dark energy and/or matter. The expansion of the universe cannot be fully explained nor agreed upon.
Therein lies openings for new physics, as a couple of key fundamentals have eluded us. Having no theory yet, I can only believe these are the the areas where the emdrive effect might reside. I cannot see fundamental physics working to explain it.
Herein lies the basis for much of the emotion about the emdrive. Does one believe new physics is even possible? IMO you would almost have to considering what we observe and cannot yet explain...gravity and the expanding universe.
I wonder if part of the divide over this is that engineers are accustomed to equipment occasionally operating in an undocumented manner while physicists rarely have an unexpected result other than a null. -
#2294 by Rodal on 27 Jan, 2016 14:31
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...These are long threads and it's the rule of the entire forum that posts need to be worthwhile. "LOLZ" and a Meme of a goldfish swearing ain't worthwhile
This thread is about the EM Drive progress. It is being used by several NASA folk (they aren't using the social media sites, per their request for me to keep what is a fringe subject alive on this site) ahead of the big tests that are coming at its next NASA center very soon. They are using this site's threads on this because of the history of the subject's progress, the crowdsourcing efforts and the quick catch up they can do on a bi-daily (or whatever) basis, where they don't have to trawl through 500 "Iz got me toaster to vibrate across me kitchen and anyone who says dat's not propellantless thrust can kiss my as*! and I'm LEAVING if u says dat!" posts because of the forum rules for the entire site's forum...
I fail to understand why a discussion about a subjectively perceived "divide between engineers and physicists" experiences is relevant to the EM Drive thread as per Chris post above.
I agree with this. Even engineers have their moments. I saw this many times, a filter tech tuning a filter meets with an Engineer who says the math is there and the filter should tune...the tech says no. They go out to the Network Analyzer and sure enough, it wasn't math that's the problem, it was unexpected electromechanical properties of the enclosure, carrier, connectors, pins, proximity, real-life Qs, you name it. Often, these were one-off events not worthy of design program updates...some helped tweaked the software to make better real-world filters. For those who have never worked in this type of environment, it can be quite entertaining...I think most of us are trying to look at the emdrive from the perspective of fundamental physics. Everything in this realm is pretty well buttoned up with the exception of gravity and "antigravity", what most call dark energy and/or matter. The expansion of the universe cannot be fully explained nor agreed upon.
Therein lies openings for new physics, as a couple of key fundamentals have eluded us. Having no theory yet, I can only believe these are the the areas where the emdrive effect might reside. I cannot see fundamental physics working to explain it.
Herein lies the basis for much of the emotion about the emdrive. Does one believe new physics is even possible? IMO you would almost have to considering what we observe and cannot yet explain...gravity and the expanding universe.
I wonder if part of the divide over this is that engineers are accustomed to equipment occasionally operating in an undocumented manner while physicists rarely have an unexpected result other than a null.
It is not the first time that this discussion is introduced into this thread. Such a discussion is psychologically subjective, as one would need at least statistical data to show that such subjective personal experiences are relevant. It is not valid in my experience. A series of confrontational posts can ensue with people arguing back and forth about their different subjective experiences with Physicists or as Engineers. How is this relevant to the EM Drive progress for spaceflight applications? but posts about pseudo-inventions that have some similarity to the EM Drive (in so far as they claimed extracting energy from "resonance with the ether" ) are deemed to not be relevant to the EM Drive thread?
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#2295 by rfmwguy on 27 Jan, 2016 14:38
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Because the emdrive discussions are looked at through several glasses. You being a PhD/theorist, others being design engineers, others being technicians and others being interested observers....These are long threads and it's the rule of the entire forum that posts need to be worthwhile. "LOLZ" and a Meme of a goldfish swearing ain't worthwhile
This thread is about the EM Drive progress. It is being used by several NASA folk (they aren't using the social media sites, per their request for me to keep what is a fringe subject alive on this site) ahead of the big tests that are coming at its next NASA center very soon. They are using this site's threads on this because of the history of the subject's progress, the crowdsourcing efforts and the quick catch up they can do on a bi-daily (or whatever) basis, where they don't have to trawl through 500 "Iz got me toaster to vibrate across me kitchen and anyone who says dat's not propellantless thrust can kiss my as*! and I'm LEAVING if u says dat!" posts because of the forum rules for the entire site's forum...
I fail to understand why a discussion about a subjectively perceived "divide between engineers and physicists" experiences is relevant to the EM Drive thread as per Chris post above.
I agree with this. Even engineers have their moments. I saw this many times, a filter tech tuning a filter meets with an Engineer who says the math is there and the filter should tune...the tech says no. They go out to the Network Analyzer and sure enough, it wasn't math that's the problem, it was unexpected electromechanical properties of the enclosure, carrier, connectors, pins, proximity, real-life Qs, you name it. Often, these were one-off events not worthy of design program updates...some helped tweaked the software to make better real-world filters. For those who have never worked in this type of environment, it can be quite entertaining...I think most of us are trying to look at the emdrive from the perspective of fundamental physics. Everything in this realm is pretty well buttoned up with the exception of gravity and "antigravity", what most call dark energy and/or matter. The expansion of the universe cannot be fully explained nor agreed upon.
Therein lies openings for new physics, as a couple of key fundamentals have eluded us. Having no theory yet, I can only believe these are the the areas where the emdrive effect might reside. I cannot see fundamental physics working to explain it.
Herein lies the basis for much of the emotion about the emdrive. Does one believe new physics is even possible? IMO you would almost have to considering what we observe and cannot yet explain...gravity and the expanding universe.
I wonder if part of the divide over this is that engineers are accustomed to equipment occasionally operating in an undocumented manner while physicists rarely have an unexpected result other than a null.
Such a discussion is psychologically subjective, as one would need at least statistical data to show that such a statement is valid. It is not valid in my experience. A series of posts can accumulate with people arguing about their experiences as Physicists or as Engineers. How is this relevant to the EM Drive progress for spaceflight applications?
It is useful to understand the different backgrounds and how we should respect other's perspective in the matter. High level theoretical discussions have their place, as do general questions, nuts and bolt questions...anything emdrive related.
It makes for a far less confrontational environment when we all understand this topic has a broad-based readership. Confrontation is what we try to avoid. -
#2296 by rfmwguy on 27 Jan, 2016 16:26
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Wise words by ISS Expedition 30/31 Flight Engineer Don Pettit in 2012 -
"Conservation of momentum applied to a rocket was first done by Russian visionary and scientist Konstantin Tsiolkovsky in 1903. All our rockets are governed by Tsiolkovsky’s rocket equation."
(snip)
"If we want to break the tyranny of the rocket equation, new paradigms of operating and new technology will be needed."
(snip)
"The discovery of some new physical principle could break the tyranny and allow Earth escape outside the governance of the rocket paradigm.
The need for new places to live and resources to use will eventually beckon humanity off this planet. Having access to space removes the lid from the Petri dish of Earth. And we all know what eventually happens if the lid is not removed."
http://www.nasa.gov/mission_pages/station/expeditions/expedition30/tryanny.html -
#2297 by zen-in on 27 Jan, 2016 16:30
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I agree with this. Even engineers have their moments. I saw this many times, a filter tech tuning a filter meets with an Engineer who says the math is there and the filter should tune...the tech says no. They go out to the Network Analyzer and sure enough, it wasn't math that's the problem, it was unexpected electromechanical properties of the enclosure, carrier, connectors, pins, proximity, real-life Qs, you name it. Often, these were one-off events not worthy of design program updates...some helped tweaked the software to make better real-world filters. For those who have never worked in this type of environment, it can be quite entertaining...I think most of us are trying to look at the emdrive from the perspective of fundamental physics. Everything in this realm is pretty well buttoned up with the exception of gravity and "antigravity", what most call dark energy and/or matter. The expansion of the universe cannot be fully explained nor agreed upon.
Therein lies openings for new physics, as a couple of key fundamentals have eluded us. Having no theory yet, I can only believe these are the the areas where the emdrive effect might reside. I cannot see fundamental physics working to explain it.
Herein lies the basis for much of the emotion about the emdrive. Does one believe new physics is even possible? IMO you would almost have to considering what we observe and cannot yet explain...gravity and the expanding universe.
I wonder if part of the divide over this is that engineers are accustomed to equipment occasionally operating in an undocumented manner while physicists rarely have an unexpected result other than a null.
I would disagree with the conclusions drawn from this statement: "engineers are accustomed to equipment occasionally operating in an undocumented manner." Everyone talks about how engineers deal with real world problems but that doesn't mean we can re-invent the laws of physics. There are always small deviations from theoretical derivations, as per the example with filters. But that is just due to the inexact nature of physical models. The laws of physics still apply. When an experiment produces an unexpected result it is a mistake to first invent new science to explain the result. An engineer worth his salt does not do that anymore than a Phd physicist does.
The em-drive's "anomalous thrust" can be completely explained by conventional Newtonian physics. If experiments were done to characterize the effects of heating the "anomalous thrust" would disappear. Instead more obscurity is pursued. Case in point: the White-Juday interferometer. I have worked with interferometers for almost 40 years and don't believe the White-Juday interferometer experiments showed anything to support em-drive theory. I discussed this at length some time ago and will not repeat myself. The most direct way of evaluating the em-drive claims is to use a systems approach. This is what engineers are trained to do. If the experiment is done on a torque pendulum any force should produce a 2nd order step response. The only time this has been seen was when there were Lorentz force errors. No new physics is needed, according to this engineer. -
#2298 by Rodal on 27 Jan, 2016 18:54
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Wise words by ISS Expedition 30/31 Flight Engineer Don Pettit in 2012 -
"Conservation of momentum applied to a rocket was first done by Russian visionary and scientist Konstantin Tsiolkovsky in 1903. All our rockets are governed by Tsiolkovsky’s rocket equation."
(snip)
"If we want to break the tyranny of the rocket equation, new paradigms of operating and new technology will be needed."
(snip)...Many re: Conservation of Energy.
Good idea !
I've said this before more obliquely, but I'll have another go. A photon rocket seems like a propellant-less thruster if you don't know that the photons carry momentum.
Let's correct this miss-perception that a photon rocket is propellant-less. See the reports below, for the fact one can call "propellant" the mass needed to be converted into photons ejected by the photon rocket (otherwise, where are the ejected photons coming from ?) but also that it needs to be as efficient as possible to convert the propellant mass into photons, like matter/antimatter reaction etc.
Interstellar photon rockets travelling at a relativistic fraction of the speed of light, would need to be many kilometers in length because of the huge amount of propellant mass needed (to be converted into photons).
http://www.dtic.mil/dtic/tr/fulltext/u2/611872.pdf
THERE WILL BE NO PHOTON ROCKET
by
V. Smilga
Translation into English from original in Russian:
Znaniye Sila (Russian), Nr. 7, 1960, pp 31-33QuoteSimple calculation says: for a rocket with a mass of a billion tons even an acceleration of 1 m/sec^2 , which
is tiny for interstellar flight, the energy of the thrust stream ejected per second amounts to a hardly comprehensible value of 10^26 to10^ 27 ergs.
It is somewhat difficult to explain these figures in earthly terms. The total energy obtained by the earth from the sun each second is about 550 times less. In order to develop 10^27ergs it is necessary to completely "cremate" 1100 kilograms of mass each second.
In other words, this energy may be obtained by exploding about a million atomic bombs.
http://www.dtic.mil/dtic/tr/fulltext/u2/264133.pdf
A PHOTON ROCKET
by
G.G. Zel'kin
Translation into English from original in Russian:
PRIRODA (Nature), NO. 11, 1960QuoteNecessary Fuel
It is extremely important to know what amount of fuel is required in order to accelerate the rocket from the initial velocity Vo to the specified final velocity V1. The initial mass of the rocket will decrease by the amount of fuel consumed.
In contrast to chemical rockets, the fuel mass of a photon rocket is commensurate with its total mass...
The general length of a photon rocket will be many km. In order to protect its crew from the lethal effects of radiation from the working photon engine, the
crew compartment will be situated ii thu nose cone of the vehicle. The instrumentsr should also be shielded from radiation.
Thus, the photon ship leaving for the limitless space of the universe will have a dry mass measured in thousands of tons.
One can imagine that the propulsion system of a photon rocket will be able to produce enormous energies. The jet stream of such a rocket, passing a planet, will
be capable of "washing-off" whole continents. It is obvious that the launching of such a rocket will be possible only from a point fairly remote from the earth.
There will be other complex problems: the problem of the efficient transformation of the mass of the substance into radiation energy, the problem of the
annihilation processes in the photon engine; the high intensity radiation in the photon rocket could, most probably, be obtained from an extremely hot plasma having
a temperature of the order of 150,OOO K or higher. It will be necessary, therefore, to have a installation assuring sufficient thermal isolation and an unusually high
capacity for letting the radiation "pass through."
The attached drawing shows the huge (due to its need for propellant mass to be converted into photons) many kilometers long photon rocket in comparison to the buildings of Moscow State University
speed of a photon rocket as a function of the ratio of its initial mass to its final mass:
where mi is the initial mass and mf is the final mass. Clearly, for speed/c to be a significant fraction of 1, one needs (initial mass) >>> (final mass)
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#2299 by rq3 on 27 Jan, 2016 21:12
