-
#2640 by Stormbringer on 05 Feb, 2016 14:21
-
I am pretty sure LIGO and LISA are designed to detect gravity waves not gravitons. We dunno much about QG but the current best guess is it would take a detector the size of Jupiter to have a hope of catching a graviton. Of course because QG has not been formalized as to which version of the theory (if any) is correct it may turn out that they are easier to detect than is currently assumed or that they are harder or impossible to detect....
We have not found WIMPS or axions, but neither have we found gravitons
...
On 11 February there will be a public announcement by LIGO (following the gossip spread around by Lawrence Krauss). So, stay tuned and maybe gravitons will never be ghosts anymore.
GR does not describe gravity using gravitons at all and GR is very successful but that does not mean that the GR model is accurately describing the universe when it comes to gravity other than it's effects. The model does not necessarily equal the thing it models. -
#2641 by StrongGR on 05 Feb, 2016 14:44
-
I am pretty sure LIGO and LISA are designed to detect gravity waves not gravitons. We dunno much about QG but the current best guess is it would take a detector the size of Jupiter to have a hope of catching a graviton. Of course because QG has not been formalized as to which version of the theory (if any) is correct it may turn out that they are easier to detect than is currently assumed or that they are harder or impossible to detect....
We have not found WIMPS or axions, but neither have we found gravitons
...
On 11 February there will be a public announcement by LIGO (following the gossip spread around by Lawrence Krauss). So, stay tuned and maybe gravitons will never be ghosts anymore.
GR does not describe gravity using gravitons at all and GR is very successful but that does not mean that the GR model is accurately describing the universe when it comes to gravity other than it's effects. The model does not necessarily equal the thing it models.
So far, we have had only indirect proof of existence of gravitational waves (Hulse and Taylor to say two). Once you know that the linearised theory works one can think to quantize it and describe what you are observing as an ensemble of gravitons. Direct evidence opens up a wealth of opportunities as also the proof of existence of the graviton itself. -
#2642 by X_RaY on 05 Feb, 2016 19:39
-
Not much posts here today. Time to look a bit of Leonard Susskind's Lectures on youtube to learn and refresh some of the basics
-
#2643 by Mulletron on 05 Feb, 2016 20:06
-
Exploring some what-if's for the future just in case. Maybe another reason why spherical end plates might be useful.
https://www.technologyreview.com/s/412674/if-superconducting-sheets-reflected-gravitational-waves/QuoteIf there were an obvious interaction between a superconducting films and gravitational waves, wouldn’t Gravity Probe B have picked them up somehow? After all, in his previous paper Chiao says that a superconducting sphere is the perfect shape for a gravitational wave antenna.
-
#2644 by RotoSequence on 05 Feb, 2016 20:08
-
With LIGO reporting the speed of gravity being the speed of light, I guess Massive Gravity is a dead idea. Back to the drawing board with any interdependent theories.
-
#2645 by Mulletron on 05 Feb, 2016 20:13
-
With LIGO reporting the speed of gravity being the speed of light, I guess Massive Gravity is a dead idea. Back to the drawing board with any interdependent theories.
I expect that to be true but do you have a reference to that report? I don't remember that being reported. -
#2646 by RotoSequence on 05 Feb, 2016 20:21
-
With LIGO reporting the speed of gravity being the speed of light, I guess Massive Gravity is a dead idea. Back to the drawing board with any interdependent theories.
I expect that to be true but do you have a reference to that report? I don't remember that being reported.
These tweeted contents are my source:
-
#2647 by flux_capacitor on 05 Feb, 2016 20:44
-
Also Dr. Brandenburg (a physicist with controversial science-fiction ideas, which I don't share. Paper on EM Drive attached below) arrives at the same conclusion using a similar theoretical formulation.
I see a mistake in Brandenburg paper (Brandenburg GEM theory of Q thruster II (3).pdf attached to your post), where he makes an analogy with the movement of particles in uniform crossed magnetic and electric fields E x B. He insists this has been verified by experiments. See Fig.5 p.6:
He states particles only accelerate in the second configuration, where a gradient in the electric field is present due to the inclination of wall electrodes. This is plain wrong. The particles would accelerate in both cases. The electric field communicates some energy to charged particles. Even if the electrodes are parallel and there is no E-field gradient, particles DO accelerate, due to the Lorentz force. This is basic magnetohydrodynamics.
Brandenburg may have mistaken MHD with EHD (electrohydrodynamics) which does not involve the Lorentz force, but a paraelectric force. And some experiments were indeed conducted by Pr. John Reece Roth at the University of Tennessee in 2001, with parallel (no E gradient) and tilted (E gradient) plate electrodes: only the tilted configuration showed an EHD acceleration. But in this case no magnetic field is involved and I think Brandenburg mixed the things up.
See Industrial Plasma Engineering Vol. 2: Applications to Nonthermal Plasma Processing for EHD references. Especially in Chapter 18 "Specialized Techniques and Devices for Plasma Processing", section 18.6 "Electrohydrodynamic (EHD) Flow Control References", fig. 18.24 page 226 and fig. 18.25 page 227, and the text beneath:
-
#2648 by rfmwguy on 05 Feb, 2016 21:31
-
Lots of key words in this paper grabbed my attention.
And if you really want to do a deep dive, it was an Airforce Research Project from Wright Patterson AFB: F33615-98-D-3210
Simulation of an asymmetric single dielectric barrier plasma actuator
(snip)
"The spatial and temporal profiles of electron density, ion density, and voltage have been obtained. The electrons and ions move in response to applied rf voltage, with the response of ions being delayed as compared to that of electrons. This results in charge separation and generation of an electrostatic field. The force is positive over the domain during the positive part of the cycle because of the obvious reason that the electric field is towards the positive direction. During the negative part of the cycle, electrons get deposited over the dielectric surface surrounding the grounded electrode, and the dielectric surface starts working as a virtual negative electrode and the effect of grounded electrode gets cut off. The force is negative only when the voltage changes sign because there is not sufficient deposition of the electrons over the dielectric surface. The time average value of force per unit area in an x direction is positive and in a y direction is negative, which implies that there is an average net electric body force on the plasma in the positive x and negative y directions. This will result in a moving wave of plasma over the dielectric surface in the direction of positive x attenuating faster outside the electrode arrangement. This will be significant for flow control and other relevant applications."
© 2005 American Institute of Physics.
http://cpdl.kettering.edu/045520JAP.pdf -
#2649 by Mulletron on 05 Feb, 2016 22:18
-
Well I'm not smart enough to answer my own question
, so I hope DrPhysicsA is. I can't find anything in the literature anywhere which supports such an outlandish idea so it's possible the error in judgement is on me. The only thing I could find is some other guy asking the same thing. http://forums.xkcd.com/viewtopic.php?f=18&t=109174 It's a tough question, because quantum mechanical objects don't actually spin in the classical way we're used to. QuoteHi Doc. I have a question. Would an atomic nucleus with spin angular momentum cause frame dragging similar to what we measured from the Earth with Gravity Probe B? I would imagine it would but it would be random framing dragging. Say I could produce a material which exhibits nuclear ferromagnetic ordering, would it produce ordered frame dragging and function as a gravitomagnet?
-
#2650 by dustinthewind on 05 Feb, 2016 22:53
-
...
From this paper I followed cited articles and found the paper below which I thought may be interesting because of the reported signals outside of a few of the microwave cavities. While it is probably just leaky signals I thought I would mention it anyways. I think it suggested graviton interaction and conversion of photons to penetrate materials and then being converted back. They even mention microwave cavities. I haven't read it all yet.
http://arxiv.org/abs/hep-th/0503158
Phys.Rev. D72 (2005) 021301
Prof. Jaffe at MIT has stated:QuoteIn discussions of the cosmological constant, the Casimir effect is often invoked as decisive evidence that the zero point energies of quantum fields are "real''. On the contrary, Casimir effects can be formulated and Casimir forces can be computed without reference to zero point energies. They are relativistic, quantum forces between charges and currents. The Casimir force (per unit area) between parallel plates vanishes as \alpha, the fine structure constant, goes to zero, and the standard result, which appears to be independent of \alpha, corresponds to the \alpha\to\infty limit.
...Quote7. Conclusions
"Pioneering experiments exploiting instead
high-quality microwave cavities for the generation and regeneration of WISPs are in the commissioning
phase."
Light shining through walls
by Javier Redondoa and Andreas Ringwalda 2010
https://scholar.google.com/scholar?cluster=9747339749210575358&hl=en&as_sdt=5,48&sciodt=0,48
One thought I had was what if unidirectional emission through the cavity by particle conversion could stir up some sort of space time breeze. -
#2651 by spupeng7 on 05 Feb, 2016 23:34
-
...
1) While Maxwell's equations are linear, the Navier Stokes equations of fluid dynamics governing thermal natural convection (lift and drag effect due to air heating) are nonlinear.
...
Firstly, thanks to you and Rmfwguy for responding to my, as yet, poorly formed question about inertia.
Secondly, reading back into thread 6 my curiosity was gripped by the notion of Maxwell's equations being linear. In what sense is this the case?
Link is to Ruth Bamford's fabulous paper, I so hope she is right about this...
-
#2652 by zen-in on 06 Feb, 2016 00:00
-
If the B field was set to 0 the charged particle would veer towards the plate that it was attracted to. The magnetic field causes the charged particle to loop around the field lines. There is a gradiant in E field in the tilted plate configuration so that should result in more acceleration to the particle. Both plate configurations will cause a charged particle to accelerate until it hits the plate it is attracted to or escapes.Also Dr. Brandenburg (a physicist with controversial science-fiction ideas, which I don't share. Paper on EM Drive attached below) arrives at the same conclusion using a similar theoretical formulation.
I see a mistake in Brandenburg paper (Brandenburg GEM theory of Q thruster II (3).pdf attached to your post), where he makes an analogy with the movement of particles in uniform crossed magnetic and electric fields E x B. He insists this has been verified by experiments. See Fig.5 p.6:
He states particles only accelerate in the second configuration, where a gradient in the electric field is present due to the inclination of wall electrodes. This is plain wrong. The particles would accelerate in both cases. The electric field communicates some energy to charged particles. Even if the electrodes are parallel and there is no E-field gradient, particles DO accelerate, due to the Lorentz force. This is basic magnetohydrodynamics.
... -
#2653 by Rodal on 06 Feb, 2016 00:08
-
Maxwell's equations are linear differential equations as long as one uses linear constitutive equations, which has been the case in all the Meep studies in these threads (although one of the powerful features of Meep is that it can analyze nonlinear constitutive equations as well), FEKO Boundary Element Method, and COMSOL Finite Element Analysis, and as shown on my T-shirt:...
1) While Maxwell's equations are linear, the Navier Stokes equations of fluid dynamics governing thermal natural convection (lift and drag effect due to air heating) are nonlinear.
...
Firstly, thanks to you and Rmfwguy for responding to my, as yet, poorly formed question about inertia.
Secondly, reading back into thread 6 my curiosity was gripped by the notion of Maxwell's equations being linear. In what sense is this the case?
Link is to Ruth Bamford's fabulous paper, I so hope she is right about this...
Since the EM Drive experiments conducted up to now have used air or vacuum as the inner medium and copper as the metal for its inner surface, there has not been a need to use a nonlinear constitutive equation. Even if one were to use a material with a nonlinear constitutive equation (nonlinear constitutive relations between the fields E, D, H and B), the nature of the nonlinearity would be clearly solely due to the nonlinearity of the material itself.
...And there was light
-
#2654 by RotoSequence on 06 Feb, 2016 01:02
-
This is a bit off topic from EM Drives themselves, but this excerpt from http://www.sciencedaily.com/releases/2016/02/160204150916.htm makes me wonder about what else can be done with resonant cavities in the field of superconductivity:Quote
It has become apparent in the past few years that the electrons involved in superconductivity can form patterns, stripes or checkerboards, and exhibit different symmetries -- aligning preferentially along one direction," said Professor Hawthorn. "These patterns and symmetries have important consequences for superconductivity -- they can compete, coexist or possibly even enhance superconductivity.
-
#2655 by Notsosureofit on 06 Feb, 2016 02:25
-
Just for fun:
Let's suppose that a photon is able to transfer all of its energy to a "dark" particle of mass 20,000 times that of the equivalent mass of the photon such that it's new kinetic energy results in a speed of 0.01c. Then the momentum exchange is 200 times that of a photon rocket.
As I said, just for fun.
Probably too much snow and too much chocolate, but I decided to calculate said "dark" particle (or at least its minimum mass) using the 500 microN maximum static force at Q=2000, P=1 kW, f=1.7 GHz from the notsosureofit hypothesis chart in the Emdrive Wiki. This is ~170 times the photon rocket force.
For a single photon interaction, the result is a mass greater than 1.6 x 10^-37 kg or 8.1 x 10^6 Gev. Pretty hefty ! But it is one way to satisfy classical COE and COM. Don't forget this is the static force.
Edit: Just thinking that there is no reason not to have "dark" particles up to the plank mass ~2.2 x 10^-8 kg, so there is plenty of room to play here.
-
#2656 by A_M_Swallow on 06 Feb, 2016 02:37
-
Just for fun:
Let's suppose that a photon is able to transfer all of its energy to a "dark" particle of mass 20,000 times that of the equivalent mass of the photon such that it's new kinetic energy results in a speed of 0.01c. Then the momentum exchange is 200 times that of a photon rocket.
As I said, just for fun.
Probably too much snow and too much chocolate, but I decided to calculate said "dark" particle (or at least its minimum mass) using the 500 microN maximum static force at Q=2000, P=1 kW, f=1.7 GHz from the notsosureofit hypothesis chart in the Emdrive Wiki. This is ~170 times the photon rocket force.
For a single photon interaction, the result is a mass greater than 1.6 x 10^-37 kg or 8.1 x 10^6 Gev. Pretty hefty ! But it is one way to satisfy classical COE and COM. Don't forget this is the static force.
Edit: Just thinking that there is no reason not to have "dark" particles up to the plank mass ~2.2 x 10^-8 kg, so there is plenty of room to play here.
Would the particle still be around when we switch the power off?
If it is not stable does it have a unique decay patten? -
#2657 by rfmwguy on 06 Feb, 2016 02:39
-
The air force contract a few posts back points to a paper about ion and electron anomalies creating a force imbalance. While I haven't fully digested it, think while others remain focused on wave theories, I'll stick with particles for the time being, specifically copper ions and free electrons until I find a brick wall. The paper describes an open system tho and not a closed cavity. So quantum tunneling is also on my short reading list...
From this paper I followed cited articles and found the paper below which I thought may be interesting because of the reported signals outside of a few of the microwave cavities. While it is probably just leaky signals I thought I would mention it anyways. I think it suggested graviton interaction and conversion of photons to penetrate materials and then being converted back. They even mention microwave cavities. I haven't read it all yet.
http://arxiv.org/abs/hep-th/0503158
Phys.Rev. D72 (2005) 021301
Prof. Jaffe at MIT has stated:QuoteIn discussions of the cosmological constant, the Casimir effect is often invoked as decisive evidence that the zero point energies of quantum fields are "real''. On the contrary, Casimir effects can be formulated and Casimir forces can be computed without reference to zero point energies. They are relativistic, quantum forces between charges and currents. The Casimir force (per unit area) between parallel plates vanishes as \alpha, the fine structure constant, goes to zero, and the standard result, which appears to be independent of \alpha, corresponds to the \alpha\to\infty limit.
...Quote7. Conclusions
"Pioneering experiments exploiting instead
high-quality microwave cavities for the generation and regeneration of WISPs are in the commissioning
phase."
Light shining through walls
by Javier Redondoa and Andreas Ringwalda 2010
https://scholar.google.com/scholar?cluster=9747339749210575358&hl=en&as_sdt=5,48&sciodt=0,48
One thought I had was what if unidirectional emission through the cavity by particle conversion could stir up some sort of space time breeze.
-
#2658 by dustinthewind on 06 Feb, 2016 06:23
-
The air force contract a few posts back points to a paper about ion and electron anomalies creating a force imbalance. While I haven't fully digested it, think while others remain focused on wave theories, I'll stick with particles for the time being, specifically copper ions and free electrons until I find a brick wall. The paper describes an open system tho and not a closed cavity. So quantum tunneling is also on my short reading list
I get the impression it is an actuator maybe similar to what a solenoid might do? It appears to separate charge using rf and some how that charge separation can move the actuator? The talk about electron deposition over a dielectric reminds me of Rodal mentioning charge separation in wave-guides in space via radiation resonance with free charge some how. He had a particular name for it I can't remember at this time. I think it was stated it could cause equipment failure in satellites and I would guess arcing or discharges. Found it: https://en.wikipedia.org/wiki/Multipactor_effect It mentions dielectrics also. Well the idea is some how the RF has to cause charge separation. I'm having a hard time visualizing the exact configuration of this particular actuator though. It's hard to me to imagine it would generate a unidirectional force though I can't say I know much about it.
There was a dielectric in the EM drive for NASA when they got it to work (well maybe they go it to work), so hmm. -
#2659 by n-s-k on 06 Feb, 2016 09:05
-
Also Dr. Brandenburg (a physicist with controversial science-fiction ideas, which I don't share. Paper on EM Drive attached below) arrives at the same conclusion using a similar theoretical formulation.
I see a mistake in Brandenburg paper (Brandenburg GEM theory of Q thruster II (3).pdf attached to your post), where he makes an analogy with the movement of particles in uniform crossed magnetic and electric fields E x B. He insists this has been verified by experiments. See Fig.5 p.6:
He states particles only accelerate in the second configuration, where a gradient in the electric field is present due to the inclination of wall electrodes. This is plain wrong. The particles would accelerate in both cases. The electric field communicates some energy to charged particles. Even if the electrodes are parallel and there is no E-field gradient, particles DO accelerate, due to the Lorentz force. This is basic magnetohydrodynamics.
Hello,
For a uniform E field, the velocity of the ExB drift (a special case of guiding center drift) is constant.
See:
https://en.wikipedia.org/wiki/Guiding_center#Electric_field
or
http://people.duke.edu/~ad159/files/p142/4.pdf
for more.
Best
, so I hope DrPhysicsA is. I can't find anything in the literature anywhere which supports such an outlandish idea so it's possible the error in judgement is on me. The only thing I could find is some other guy asking the same thing.