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#2240 by Rodal on 18 Oct, 2017 14:14
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Can someone please explain why the sorbothane pads used by Jamie, which are intended to absorb and diminish vibrations transmitted to the setup, seem to conversely do the opposite? Is there an effect of resonance, relative to their size, thickness, and the size of the setup? Or may it be just a bad junction between bolt and screw as DusanC supposed?
These pads are just a polyurethane "hockey puck" (a solid disc), that has a stiffness much smaller than the stiffness of the legs and the foundation. (Sorbothane is just a tradename for a particular thermoset polyether-based polyurethane. ) They artificially introduce a compliance element [a spring with much lower stiffness] that will result in significantly lower natural frequencies (mainly due to the table rocking, with the pads under shear ). The dissipation of energy they introduce is only a fraction of the energy of vibration (the dissipation is governed by the material property tan delta, which ranges from ~0.2 to ~0.5 for this polyurethane compound). If they (due to their much lower stiffness) introduce a natural frequency that can be easily excited by excitations in the environment, one may be better off eliminating these compliant elements all together. Alternatively, one could change the natural frequency artificially introduced by the Sorbothane pads by changing the stiffness of the pad by decreasing their thickness, (hence increasing the stiffness and hence increasing the natural frequency of the table), changing the material (Sorbothane comes in several durometer hardness) or by increasing the mass in the table (thereby decreasing the natural frequency of the table).
In other words, the answer to your question << Is there an effect of resonance, relative to their size, thickness, and the size of the setup?>> is definitely YES, of course. The present Sorbothane pads do not seem to be well-matched to the mass of the table and the excitation frequencies present in the environment. (Which is no surprise since nobody conducted a vibration analysis of this setup with this Sorbothane pads
, they were just put there hoping -rather than calculating whether they would introduce additional natural frequencies - that they would absorb energy).
Concerning the ability of the Sorbothane pads to shear (they have unconstrained lateral cylindrical surface of course) this is intended: without deformation they will have no ability to dampen anything.
Solid thermoset polyurethane has a Poisson's ratio practically equal to 1/2: it is practically incompressible, like rubber. Hence if you were to constrain the cylindrical surface, their stiffness would increase by orders of magnitude and they would not serve their intended purpose [since the bulk modulus of this material is many orders of magnitude greater than the shear modulus, and since the quoted tan delta dissipation value is for shear deformation mode and not for bulk modulus deformation mode]
These Sorbothane pads come in at least 3 different hardnesses: 30, 50 and 70 durometer [Shore scale "OO": spring force 1.11 N with a probe's spherical radius 1.2 mm]. The properties depend on the particular hardness that Monomorphic used. What durometer hardness are the pads that Monomorphic used?
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#2241 by meberbs on 18 Oct, 2017 15:25
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You mean for some reason like gravity? You are just going in a big circle here adding a bunch of unnecessary steps to then write down the original conclusion. Even if your explanation actually involved time dilation in any way (you can't jump from particles with negative mass travelling backwards in time -> time dilation), your explanation still does not account for time dilation from non-gravity based accelerations
Gravity is more than just time dilation, and time dilation is caused by any acceleration (or just by having a relative velocity) so it doesn't make sense to say that time dilation causes gravity.Time is gravity?
Almost Kenjee,
gravity is time dilation, to be more specific. Problem is we don't really know how time dilation acts to engender gravitational acceleration, do we... Ideas anyone?
That seems to me to be in question because we don't really know the source of what causes the time gradient. It is really just because of relative velocity (or existing under acceleration) or something more fundamental that causes time to change?
For instance what if the vacuum is made up of positive matter that runs forward in time and negative energy matter that run backwards in time. The negative energy matter appearing in our universe as positive energy matter because it runs backwards in time but then it annihilates with positive energy matter their time cancels out between them and suddenly they annihilate. While separation because of the time aspect allows them to have what appears as positive energy.
Maybe for some reason this negative energy matter in the vacuum is attracted to large masses of positive energy matter.Maybe having a large velocity in the vacuum also polarizes these particles causing Lorentz contraction and the time effects.
"Large velocity in the vacuum" does not make any sense and contradicts the essence of special relativity, that there is no vacuum rest frame. -
#2242 by Mulletron on 18 Oct, 2017 15:38
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You mean for some reason like gravity? You are just going in a big circle here adding a bunch of unnecessary steps to then write down the original conclusion. Even if your explanation actually involved time dilation in any way (you can't jump from particles with negative mass travelling backwards in time -> time dilation), your explanation still does not account for time dilation from non-gravity based accelerations
Gravity is more than just time dilation, and time dilation is caused by any acceleration (or just by having a relative velocity) so it doesn't make sense to say that time dilation causes gravity.Time is gravity?
Almost Kenjee,
gravity is time dilation, to be more specific. Problem is we don't really know how time dilation acts to engender gravitational acceleration, do we... Ideas anyone?
That seems to me to be in question because we don't really know the source of what causes the time gradient. It is really just because of relative velocity (or existing under acceleration) or something more fundamental that causes time to change?
For instance what if the vacuum is made up of positive matter that runs forward in time and negative energy matter that run backwards in time. The negative energy matter appearing in our universe as positive energy matter because it runs backwards in time but then it annihilates with positive energy matter their time cancels out between them and suddenly they annihilate. While separation because of the time aspect allows them to have what appears as positive energy.
Maybe for some reason this negative energy matter in the vacuum is attracted to large masses of positive energy matter.Maybe having a large velocity in the vacuum also polarizes these particles causing Lorentz contraction and the time effects.
"Large velocity in the vacuum" does not make any sense and contradicts the essence of special relativity, that there is no vacuum rest frame.
This sure looks like an acceleration to me. A constantly changing acceleration.
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#2243 by sanman on 18 Oct, 2017 16:30
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I appreciate the offer, but for now I think this is better worked out in public. For one thing, as was stated above by Mulletron, one of the benefits of the emDrive is getting people to think, but thinking based on falsehoods is unhelpful, so I want to correct the repeated false statements you have made.
Sir, as I've nothing to hide, I will try to create another thread for us to discuss/debate.
(I simply wanted to avoid cluttering this thread where other nice discussions are taking place)QuoteNo, it is not a straw man, I am giving it as an example, and you just now have described what you think happens in this situation. What you just described is wrong. You start off fine with "agree with you that entropy of the component objects of the universe affect the total entropy of the universe"
But then you contradict this with the claim that the total entropy of the universe does not increase faster when the log is on fire. This claim is simply wrong. If I were to write your claim mathematically, it would be equivalent to 1+2 = 1 (base rate of universal entropy increase + additional rate of increase due to log burning = base rate of universal entropy increase.)
No, what I was saying was that the Total Change of the Entropy of the Universe (and also the Total Rate of Change) is NOT EQUAL to the Change of Entropy from the log (or Rate of Change of it), since obviously the universe also has other things going on beyond what is happening to just that log.QuoteQuote
This is all wrong. You cannot do what you claim. Go ahead and try. (Here is a hint to get you started: entropy is constant in the system. There is no external observer required for 2 balls to collide. If you want to bring in an external observer, you are going to then have to describe a mechanism where the balls magically start moving faster when entropy starts increasing faster elsewhere, such as by someone lighting a log on fire)QuoteCompletely false. Time is physical. You cannot write the laws of physics without time. You cannot use entropy to fully describe an elastic collision between 2 balls, but you do need to use time to do so.
Sure you can, because the person observing the collision (or the universe inside which the collision is occurring) is undergoing entropy progression which you call passage of Time. Time is a representation of Entropy (with Entropy being the more meaningful property)
I apologize - I thought you were saying something else about kinematics against the wider universe, but you were simply just talking about isentropic elastic collision between balls. In that case, you're referring to hypothetical no-entropy universe, which is just as unreal as if I'd offered the situation of a static universe which is not undergoing change in time. In the real world, when 2 balls collide, there will always be an entropy change - your hypothetical situation does not describe the real world.QuoteYou seem to be under some kind of mistaken assumption where you think entropy must always be increasing. There is no such rule in physics, the only rule is that it cannot decrease globally. It can stay constant.
Entropy of the universe (the real universe, and not some idealized one) is always increasing.
2nd Law of Thermodynamics
https://www.calpoly.edu/~rbrown/entropy.htmlQuoteAny process either increases the entropy of the universe - or leaves it unchanged. Entropy is constant only in reversible processes which occur in equilibrium. All natural processes are irreversible.
All natural processes tend toward increasing disorder.QuoteAny process either increases the entropy of the universe - or leaves it unchanged. Entropy is constant only in reversible processes which occur in equilibrium. ... All natural processes tend toward increasing disorder. And although energy is conserved, its availability is decreased.
QuoteAll natural processes occur in such a way that the total entropy of the universe increases.
Please note the word "natural".
Reversible processes in our macroscopic world are idealized ones, and not real ones.QuoteNo, forgetting something would entail a local entropy increase, but storing a memory would by definition be a local increase. Chemical reactions can occur that locally decrease entropy, as long as the cost is simultaneously paid (metabolic processes).
As per what you've just said - an increase (forgetting) and an increase (storing) - it's once again consistent with the fact that entropy is always increasing.
From the Physics Review:
https://physics.aps.org/articles/v7/47QuoteHow we actually perceive the flow of time is another matter. Theorists have argued that recording information always involves erasing—for example, initializing a computer memory at the start [1]. Since erasure always increases entropy [2], the psychological arrow of time aligns with the thermodynamic one.
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You can, in principle, get rid of any need for erasure and initialization just by remembering everything—which means that recording information in the memory is then fully reversible in time. But even in that case the arrows of time must align because, says Brun, “there is a broader principle at work.”
The researchers argue that this extra ingredient is something they call generality.
... (read the rest, too long, phew! )
Once again, I apologize to you and everyone else for cluttering this thread with my argumentativeness.
I'll try to create a separate thread - as soon as I can pick a suitable title - Phew!
But once again, I remind that reversible no-entropy processes are idealized ones, and are not real-world. In the real world, entropy always increases. There is no natural process that can occur without increasing entropy.
https://en.wikipedia.org/wiki/Entropy#The_arrow_of_timeQuoteThe arrow of time
Entropy is the only quantity in the physical sciences that seems to imply a particular direction of progress, sometimes called an arrow of time. As time progresses, the second law of thermodynamics states that the entropy of an isolated system never decreases. Hence, from this perspective, entropy measurement is thought of as a kind of clock. -
#2244 by Tcarey on 18 Oct, 2017 16:44
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Just subtracting the blue and orange traces eliminates the slow noise. The question would be, when the Frustum is powered, does the reaction happen fast enough to cause a differential in the two sensors? But I don't think that's what Bob012345 had in mind. Connecting an Op-amp to the signal to drive the Electromagnet in opposition to the noise, could be used as a feedback loop to stabilize the arm.
Still, since the noise has a period of 30 to 60 seconds, and the Frustum can charge to full power, Max Q in what, microseconds (??), I don't see the problem. The low frequency noise would only be an issue if the thrust is due to thermal heating, not "something else", I think. What you need to determine is if the signal is significant compared to the noise.
Since the red and blue lines represent the opposite end of the beam, would subtracting them from each other negate any signal at all? Also the theory of placing the measuring system on a foam pad would not likely diminish any vibration that has a such a long time period. I would like to see a test of the system with the suspended arm rigidly fixed to the supporting frame. That would indicate whether the signal is actual movement or some sort of artifact of the measuring system as a whole.
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#2245 by Subocaji on 18 Oct, 2017 17:03
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Correct me if I'm wrong but didn't rfmwguy hand his matterials of to Northrop Grumman and now they have a semi hush,hush launch on a SpaceX rocket this November.
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#2246 by meberbs on 18 Oct, 2017 17:49
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This sure looks like an acceleration to me. A constantly changing acceleration.
How is this in any way relevant?
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#2247 by meberbs on 18 Oct, 2017 17:50
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Correct me if I'm wrong but didn't rfmwguy hand his matterials of to Northrop Grumman and now they have a semi hush,hush launch on a SpaceX rocket this November.
I don't believe he ever said who he handed it off to, almost certainly not Northrop, and he certainly didn't hand it off to them years ago when Northrop contracted SpaceX. -
#2248 by Subocaji on 18 Oct, 2017 17:56
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This was posted under his reddit handle 6 months ago>
rarely post nowadays, but I want to announce to the reddit crew that my EmDrive was delivered more than 90 days ago to a division of Northrop Grumman. I chose to announce this as I have not been updated, nor expect to be in the near future. This could be caused by many reasons and I am really not interested in pushing the issue. I have no ill-will towards my contacts and wish them all the best. If they chose not to pursue, it would have been nice to get a confirmation of that, but alas, its a giant corporation and they have the right to proceed as they see fit.
Some may find this strange that I simply turned over the prototype without locking down a firm contract, but my intention was never to monetize the emdrive project. I have no interest in the fame nor the $$. I started it as an open project and finished it as such, staying true to myself and I hope to the followers that came with me along the way.
So, my retirement from this project continues...However, there are always new possibilities. Peace - out.
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#2249 by dustinthewind on 18 Oct, 2017 18:31
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You mean for some reason like gravity? You are just going in a big circle here adding a bunch of unnecessary steps to then write down the original conclusion. Even if your explanation actually involved time dilation in any way (you can't jump from particles with negative mass travelling backwards in time -> time dilation), your explanation still does not account for time dilation from non-gravity based accelerations
Gravity is more than just time dilation, and time dilation is caused by any acceleration (or just by having a relative velocity) so it doesn't make sense to say that time dilation causes gravity.Time is gravity?
Almost Kenjee,
gravity is time dilation, to be more specific. Problem is we don't really know how time dilation acts to engender gravitational acceleration, do we... Ideas anyone?
That seems to me to be in question because we don't really know the source of what causes the time gradient. It is really just because of relative velocity (or existing under acceleration) or something more fundamental that causes time to change?
For instance what if the vacuum is made up of positive matter that runs forward in time and negative energy matter that run backwards in time. The negative energy matter appearing in our universe as positive energy matter because it runs backwards in time but then it annihilates with positive energy matter their time cancels out between them and suddenly they annihilate. While separation because of the time aspect allows them to have what appears as positive energy.
Maybe for some reason this negative energy matter in the vacuum is attracted to large masses of positive energy matter.Maybe having a large velocity in the vacuum also polarizes these particles causing Lorentz contraction and the time effects.
"Large velocity in the vacuum" does not make any sense and contradicts the essence of special relativity, that there is no vacuum rest frame.
Supposing anti-matter is this other component it would have to be attracted for some other reason than gravity for it to work. It is attracted to its counterpart so maybe it is feasible for it to be attracted to other large quantities of positive time matter, hypothetically speaking. It could polarize at some equilibrium between its positive time partner and the other positive time particle with out a partner. Maybe for electric field reasons or some other reason. The polarization of this negative time aspect in the vacuum would then induce gravity. It's an incomplete work but something I have mulled over from time to time. -
#2250 by meberbs on 18 Oct, 2017 18:42
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Supposing anti-matter is this other component
Are you trying to describe the universe we live in, or some other fictional universe?
This is simply a non-starter of a proposition. If there was large quantities of antimatter to cause these effects, it would be impossible to not see them.
Also, consensus is that anti-matter has the same interaction with gravity as normal matter, meaning it would be attracted to regular matter by gravity, though it hasn't been conclusively measured yet.
You also did not actually address what I said. -
#2251 by Mulletron on 18 Oct, 2017 18:51
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This sure looks like an acceleration to me. A constantly changing acceleration.
How is this in any way relevant?
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I'm sorry, I thought it was obvious. It's an acceleration isn't it? You said any acceleration, so I replied with the wave behavior of the superposition of two waves of different amplitude. This is analogous to what's happening in a resonator with asymmetric losses. -
#2252 by meberbs on 18 Oct, 2017 20:04
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It is an acceleration if you are talking about a physical resonator, such as waves on a string, but not if you are talking about one where it is something like electromagnetic fields that are doing the oscillating.This sure looks like an acceleration to me. A constantly changing acceleration.
How is this in any way relevant?
...
I'm sorry, I thought it was obvious. It's an acceleration isn't it? You said any acceleration, so I replied with the wave behavior of the superposition of two waves of different amplitude. This is analogous to what's happening in a resonator with asymmetric losses.
Going with the waves on a string, so that you are talking about something where acceleration applies, then yes, there is acceleration, so as I said, there will be relativistic time dilation from the accelerations, but they obviously would be miniscule for most physical systems. (And yes oscillating EM fields would originate from oscillating charges, and those charges therefore accelerate and would experience time dilation)
Again, what relevance does this example of an acceleration have to the point that spupeng7's and dustinthewind's descriptions are not compatible with known effects? -
#2253 by Mulletron on 18 Oct, 2017 20:26
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It is an acceleration if you are talking about a physical resonator, such as waves on a string, but not if you are talking about one where it is something like electromagnetic fields that are doing the oscillating.This sure looks like an acceleration to me. A constantly changing acceleration.
How is this in any way relevant?
...
I'm sorry, I thought it was obvious. It's an acceleration isn't it? You said any acceleration, so I replied with the wave behavior of the superposition of two waves of different amplitude. This is analogous to what's happening in a resonator with asymmetric losses.
Going with the waves on a string, so that you are talking about something where acceleration applies, then yes, there is acceleration, so as I said, there will be relativistic time dilation from the accelerations, but they obviously would be miniscule for most physical systems. (And yes oscillating EM fields would originate from oscillating charges, and those charges therefore accelerate and would experience time dilation)
Again, what relevance does this example of an acceleration have to the point that spupeng7's and dustinthewind's descriptions are not compatible with known effects?
I see you expanded your question. I'm not supporting spupeng7 or dusty's descriptions, I'm supporting and developing my own. I disagree with your first sentence. Why do you think this only applies to things like waves on a string? Why the arbitrary line? Are you drawing the line because of mass? Thanks. -
#2254 by meberbs on 18 Oct, 2017 20:47
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I see you expanded your question. I'm not supporting spupeng7 or dusty's descriptions, I'm supporting and developing my own. I disagree with your first sentence. Why do you think this only applies to things like waves on a string? Why the arbitrary line? Are you drawing the line because of mass? Thanks.
To start with the answer your last question, yes. The physics concept of "acceleration" simply only applies to massive particles.
Massless particles like photons have relativistic effects applied to them, but you can't sensibly discuss accelerations of them, since they only move at the speed of light.
Fields themselves can have a "rate of change" and a "rate of rate of change" associated with them, but these have units such as "field strength per time" rather than "distance per time", so while the informal term "acceleration" could apply, none of the physics related to accelerating particles does. To avoid confusion, it is best not to call this "acceleration of the field" but "second time derivative of the field." -
#2255 by SeeShells on 18 Oct, 2017 20:49
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Nice write up Dr. Rodal. It's also important to make sure the attached hardware is also stable with a uniform load distribution. The bolt on the bottom touching the washer isn't a uniform load bearing surface and where the bolt goes through the aluminum frame can wiggle.
ShellCan someone please explain why the sorbothane pads used by Jamie, which are intended to absorb and diminish vibrations transmitted to the setup, seem to conversely do the opposite? Is there an effect of resonance, relative to their size, thickness, and the size of the setup? Or may it be just a bad junction between bolt and screw as DusanC supposed?
These pads are just a polyurethane "hockey puck" (a solid disc), that has a stiffness much smaller than the stiffness of the legs and the foundation. (Sorbothane is just a tradename for a particular thermoset polyether-based polyurethane. ) They artificially introduce a compliance element [a spring with much lower stiffness] that will result in significantly lower natural frequencies (mainly due to the table rocking, with the pads under shear ). The dissipation of energy they introduce is only a fraction of the energy of vibration (the dissipation is governed by the material property tan delta, which ranges from ~0.2 to ~0.5 for this polyurethane compound). If they (due to their much lower stiffness) introduce a natural frequency that can be easily excited by excitations in the environment, one may be better off eliminating these compliant elements all together. Alternatively, one could change the natural frequency artificially introduced by the Sorbothane pads by changing the stiffness of the pad by decreasing their thickness, (hence increasing the stiffness and hence increasing the natural frequency of the table), changing the material (Sorbothane comes in several durometer hardness) or by increasing the mass in the table (thereby decreasing the natural frequency of the table).
In other words, the answer to your question << Is there an effect of resonance, relative to their size, thickness, and the size of the setup?>> is definitely YES, of course. The present Sorbothane pads do not seem to be well-matched to the mass of the table and the excitation frequencies present in the environment. (Which is no surprise since nobody conducted a vibration analysis of this setup with this Sorbothane pads , they were just put there hoping -rather than calculating whether they would introduce additional natural frequencies - that they would absorb energy).
Concerning the ability of the Sorbothane pads to shear (they have unconstrained lateral cylindrical surface of course) this is intended: without deformation they will have no ability to dampen anything.
Polyurethane has a Poisson's ratio practically equal to 1/2: it is practically incompressible, like rubber. Hence if you were to constrain the cylindrical surface, their stiffness would increase by orders of magnitude and they would not serve their intended purpose [since the bulk modulus of this material is many orders of magnitude greater than the shear modulus, and since the quoted tan delta dissipation value is for shear deformation mode and not for bulk modulus deformation mode]
These Sorbothane pads come in at least 3 different hardnesses: 30, 50 and 70 durometer [Shore scale "OO": spring force 1.11 N with a probe's spherical radius 1.2 mm]. The properties depend on the particular hardness that Monomorphic used. What durometer hardness are the pads that Monomorphic used? -
#2256 by Star One on 18 Oct, 2017 21:05
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New article.Quote
A new study from the University of Lisbon claims that a particularly overlooked theory in quantum mechanics called the pilot wave could explain a working EM Drive. However, there's much to be discussed about the viability of this assumption.
https://futurism.com/everything-you-need-to-know-about-the-latest-physics-breaking-em-drive-research/ -
#2257 by RERT on 18 Oct, 2017 21:58
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We do know how time dilation induces gravitational effects. In the presence of a variable 'rate of time' the geodesic paths are accelerated - like gravity. Newtonian gravity can be accounted for by only varying the rate of time. GR requires changes in the space dimensions as well.
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#2258 by meberbs on 18 Oct, 2017 22:08
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We do know how time dilation induces gravitational effects.
We do not know that it does. In fact to the contrary, gravitational effects cause time dilation, not the other way around. Saying that we know how something happens that does not happen is 2 levels of wrong.In the presence of a variable 'rate of time' the geodesic paths are accelerated - like gravity. Newtonian gravity can be accounted for by only varying the rate of time. GR requires changes in the space dimensions as well.
Newtonian gravity does not have any time dilation. also, "rate of time" is not a defined physics term, so I am just assuming you mean "time dilation." -
#2259 by Mulletron on 18 Oct, 2017 23:12
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I see you expanded your question. I'm not supporting spupeng7 or dusty's descriptions, I'm supporting and developing my own. I disagree with your first sentence. Why do you think this only applies to things like waves on a string? Why the arbitrary line? Are you drawing the line because of mass? Thanks.
To start with the answer your last question, yes. The physics concept of "acceleration" simply only applies to massive particles.
Massless particles like photons have relativistic effects applied to them, but you can't sensibly discuss accelerations of them, since they only move at the speed of light.
Fields themselves can have a "rate of change" and a "rate of rate of change" associated with them, but these have units such as "field strength per time" rather than "distance per time", so while the informal term "acceleration" could apply, none of the physics related to accelerating particles does. To avoid confusion, it is best not to call this "acceleration of the field" but "second time derivative of the field."
Thank you for your response. When I occasionally change perspective from the classical behavior of waves to that of the quantum mechanical massless photon (which I've learned isn't useful for reasons I'll get to in a bit further down in the paragraph) I invoke the understanding that a system of two or more counterpropagating photons is massive, and that mass can be accelerated. It's turning into a complicated mess for me to be able to understand using this approach.
I find it more appealing to stick to classical wave behavior, and deal with the flow of energy and momentum in one particular direction vice another. I know this from the stress energy tensor. Newtonian physics was all about mass, but Einstein taught us that energy is (and momentum) are more fundamental. All this started with trying to find the "missing Poynting vector" over the years of this thread. I'm gathering my observables to make a calculation. I may just make a toy model instead. I share Rodal's concerns with how this satisfies E field boundary conditions. These animations I've been showing about superposition of waves aren't taking into respect boundary conditions so I get that. I understand that half of the energy is in the magnetic field and half is in the electric field.
, they were just put there hoping -rather than calculating whether they would introduce additional natural frequencies - that they would absorb energy).