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#1




Verifying
If there is anew kind of attractive force, unknown to us, that pulls
matter together, we should be able to see some effects of this feeble force in our environment. Now, consider the earth moon system. We have a mirror there, that can reflect any laser beam to the earth. The orbit of the moon should be affected if the geometry works. When the moon is moving away from the center of the galaxy it should feel a braking effect. Wehn it is approaching, an accelerating effect. Over time these effects could accumulate. Contrary to the noise, the acceleration should always have a vector pointing to the Sagitarius constellation. We have extremely precise clocks, and we have even detected gravitational waves. I do not think that detecting this force is very difficult, if it can be done at all, of course. And if it is not detected, it is surely an argument againt that supposition. There many reasons that the experiment could fail. Braking effects of the tides, and many others, influences of other planets, etc. Taking all that into account is a considerable work. How big is that force? Those stars must be pulled somehow, by this attractive force, so that their rotation doesn't go down as distance increases. This force holds the galaxy together. But as distance increases, the force decreases. Nuclear force is very strong but doesn't reach very far. Gravity is much weaker but reaches farther, much farther. But gravity decreases as the square of distance, and doesn't reach as far as this new force, even feebler than gravity. But it is feasible for astronomers to catch it now, they have all the required technology. Nobody is looking however. Looking for perturbations in the orbits of the planets that point to the center of the galaxy. 
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#2




Verifying
On 11/4/2017 9:01 PM, jacobnavia wrote:
If there is anew kind of attractive force, unknown to us, that pulls matter together, we should be able to see some effects of this feeble force in our environment. Only if it is strong enough at the (relatively) short distances of "our environment". Now, consider the earth moon system. We have a mirror there, that can reflect any laser beam to the earth. We also have satellites and spacecraft at larger distances. ... We have extremely precise clocks, and we have even detected gravitational waves. I do not think that detecting this force is very difficult, So you have information as to whether it is strong enough at the relatively short distances of our environment, as mentioned above? ... But gravity decreases as the square of distance, and doesn't reach as far as this new force, even feebler than gravity. OK, you propose a force decaying more slowly than 1/r^2 But it is feasible for astronomers to catch it now, they have all the required technology. Nobody is looking however. Looking for perturbations in the orbits of the planets that point to the center of the galaxy. You are mistaken, people are constantly looking. Remember all the activity related to the Pioneer anomaly, or more recently (and based on the orbits of the planets) the search for planet nine. But all this analysis of forces (at the relatively short distances of our environment) just hasn't (yet) provided any evidence for the longrange force that you propose! You should be more patient. (At least for planet nine now the evidence is mounting..)  Jos 
#3




Verifying
On 11/5/17 2:05 AM, Jos Bergervoet wrote:
You are mistaken, people are constantly looking. Remember all the activity related to the Pioneer anomaly In reference to the Pioneer Anomaly the most definite conclusion is based on the JPL report: http://arxiv.org/abs/1204.2507 [[Mod. note  Published as Phys Rev Lett 108, 241101. The same authors' (Rutyshev et al) previous paper, arXiv:1107.2886 = Phys Rev Lett 107, 081103, is also essential reading. The thermal modelling is discussed in more detail in Rievers et al, New J Physcs 11, 113032 http://dx.doi.org/10.1088/13672630/11/11/113032 and the same authors' (Rievers et al) later paper arXiv:1104.3985 = Annelen der Physik 523, 439 http://dx.doi.org/10.1002/andp.201100081  jt]] It does not reflect the thermal and Doppler solutions over time. With time, the constant Doppler solution dominates the decaying thermal solution as the Pioneers approach interstellar space. The Doppler solution is real versus the 1000s of calculated decaying internal finite element diminishing contributions. This JPL analysis failure unnecessarily negates a major contribution to science. I am not talking about new physics but a confirmation of space time. The JPL report has a geocentric/heliocentric view and dismisses the universal view. The JPL analysis is based on incomplete analysis of the data assuming the decay for Pioneer acceleration aP daP/dt = k*aP model one This fits the assumption that the thousands of analyzed aP thermal components are tied to the RTG half life with aP decay approaching zero with time. A better fit to trajectory data is the 'aPinfinity' effect as the Pioneers approached interstellar space: daP/dt = k*(aP  aPinfinity) model two Initially, as the Pioneers pass Jupiter, the thermal emission overwhelms the anomalous acceleration (aPinfinity) making it statistically insignificalt in this initial trajectory phase but diminishes with time(model one) with aP decay approaching aPinfinity with time (model two) as the Pioneers probe interstellar, intergalactic space on leaving the solar system with diminished internal thermal and external solar wind considerations previously considered. Statistically significant aPinfinity values a Pioneer 10 aPinfinity 7.0x10^10 m/sec^2 Pioneer 11 aPinfinity 8.2x10^10 m/sec^2 These values may represent a constant for interstellar medium within some standard deviation or actually represent different values based on differing Pioneer 10 and 11 directional probes of interstellar medium. The interstellar medium may not be uniform. Logically, in as much as aPinfinity is a measure of spacePioneer momentum transfer (spacetime viscosity) then all transiting object motion would be affected. This has implication for galactic and planetary system formation as reflected in accelerations associated with the Tully Fischer relationship. Apparently there is still some unpublished Pioneer data to further test this hypothesis. Considering this data's importance to the scientific community, it should be published. RDS 
#4




Verifying
jacobnavia writes:
Now, consider the earth moon system. We have a mirror there, that can reflect any laser beam to the earth. Five, actually, regularly pinged looking for deviations: "Tests of Gravity Using Lunar Laser Ranging" (2010) https://link.springer.com/article/10.12942/lrr20107 "Lunar laser ranging: the millimeter challenge" (2013) https://arxiv.org/abs/1309.6294 see also https://en.wikipedia.org/wiki/Apache...ging_Operation https://tmurphy.physics.ucsd.edu/apollo/apollo.html The latest observations are limited by the physical characteristics of the reflectors. Nobody is looking however. ?? dan [[Mod. note  One particularly fascinating part of the lunarlaserranging story is the unexpectation degredation of the retroreflectors, apparently due to thermal gradients caused by lunar dust coating the reflector surfaces. I think this was first published in https://arxiv.org/abs/1003.0713 and there's a nice summary and update in section 4.2 of the 1309.6294 paper.  jt]] 
#5




Verifying
Le 05/11/2017 =C3=A0 09:05, Jos Bergervoet a =C3=A9crit=C2=A0:
So you have information as to whether it is strong enough at the relatively short distances of our environment, as mentioned above? Suppose some star S at 60 thousand light years from the center of the galaxy. A normal star whose mass can be accurately determined. Its speed can be measured, and its mass is known. Then, we subtract gravity effects and we obtain the force that is necessary to accelerate that star to its observed speed at 60000 light years from the center. Supposing a roughly linear decay, here at only 30000 light years from the center we should have half of that. Looks simple but can't be that simple. I am surely missing something, but what? [[Mod. note  There are a couple of things: 1. A solartype star at a distance of 60,000 lightyears has an apparent magnitude of around 21, which is faint enough that getting a good spectrum will take a lot of bigtelescope time. 2. Once you get that spectrum you get the star's radial velocity (its velocity along our lineofsight to the star). But if you want all 3 components of its vector velocity you also need to measure its velocity perpendicular to our lineofsight. That means doing highprecision astrometry to measure how its position gradually drifts relative to other more distant objects, with corrections for the Earth's motion around the center of our own galaxy. (This will be on the order of microarcseconds/year.) This star is too faint for Gaia to give good data (Gaia's error bars are up to 200 microarcseconds/year at magnitude 20), in fact I can't think of any current telescope/detector that could do relative astrometry at that accuracy level on an object that faint in a reasonable amount of telescope time. 3. Suppose we somehow managed to measure all 3 components of the star's vector *velocity*. That doesn't tell us anything about the star's gravitational *acceleration* (we don't know that it's moving in a circular orbit about the center of our galaxy!), which is the quantity which is actually influenced by dark matter/modified gravity.  jt]] 
#6




Verifying
Le 08/11/2017 à 20:33, jacobnavia a écritÂ :
Le 05/11/2017 Ã 09:05, Jos Bergervoet wrote: So you have information as to whether it is strong enough at the relatively short distances of our environment, as mentioned above? Suppose some star S at 60 thousand light years from the center of the galaxy. A normal star whose mass can be accurately determined. Its speed can be measured, and its mass is known. Then, we subtract gravity effects and we obtain the force that is necessary to accelerate that star to its observed speed at 60000 light years from the center. Supposing a roughly linear decay, here at only 30000 light years from the center we should have half of that. Looks simple but can't be that simple. I am surely missing something, but what? [[Mod. note  There are a couple of things: 1. A solartype star at a distance of 60,000 lightyears has an apparent magnitude of around 21, which is faint enough that getting a good spectrum will take a lot of bigtelescope time. We have big scopes now. Or just choose a nearer one. The farther you go, the more the discrepancyy between gravity and its observed speed should be, as we read from the speed charts of stars around the center. The difference is bigger when you get away from the galaxy, at the outskirts. 2. Once you get that spectrum you get the star's radial velocity (its velocity along our lineofsight to the star). But if you want all 3 components of its vector velocity you also need to measure its velocity perpendicular to our lineofsight. Mmm the galaxy has a plane of rotation. Th center of the galaxy, that star and we are rotating around the same central object, the galaxy, in a plane. The center, we, and that star are in the same plane. Are those corrections really necessary? That means doing highprecision astrometry to measure how its position gradually drifts relative to other more distant objects, with corrections for the Earth's motion around the center of our own galaxy. (This will be on the order of microarcseconds/year.) This star is too faint for Gaia to give good data (Gaia's error bars are up to 200 microarcseconds/year at magnitude 20), in fact I can't think of any current telescope/detector that could do relative astrometry at that accuracy level on an object that faint in a reasonable amount of telescope time. We can use stars nearer of course. For instance at mag 20 if that is the limit of Gaia. That would be a good start. 3. Suppose we somehow managed to measure all 3 components of the star's vector *velocity*. That doesn't tell us anything about the star's gravitational *acceleration* (we don't know that it's moving in a circular orbit about the center of our galaxy!), which is the quantity which is actually influenced by dark matter/modified gravity.  jt]] "We don't know that is moving in a circular orbit"... wow, I always thought that they are doing so, and that the "arms" we see are density waves in the disc of stars circling the center. The stars must be doing "some" kind of circle around the center since the form of the galaxy (a rotating plane of stars ) indicates so. I even thought that the sun was rotating about 1 rotation per 250 million years, so it is around 20 galactic years old. I thought that the orbit was a circle. Is that not correct? If we approximate the orbit by some kind of circle, we approximate the milky way to a center of gravity around the black hole in the central buldge, we can calculate the gravity exerced by the (I suppose known) mass of the galaxy and the speed that a star should have isn't it? Very roughly. A more sophisticated thing would take into account the form of the buldge, the mass of the plane inside the orbit, etc. Dark matter scenarios suppose some form of invisible matter outside and propose a vector that is in the opposite direction pulling the stars. The force the stars feel would come from outside the galaxy in some kind of halo. Maybe we could look in the other direction. And if the force came from the galaxy itself? A second star we could use of course, is the nearest one, the sun. The sun's orbit could tell us about the force effects here. Here we have more data and less problems than with the star's far away. We know very precisely the distance to the center, and the mass between us and the center, so the effects of gravity could be calculated much more easily. Is there any delta? Has anyone done this calculations? 
#7




Verifying
On 11/4/17 3:01 PM, jacobnavia wrote:
If there is anew kind of attractive force, unknown to us, that pulls matter together, we should be able to see some effects of this feeble force in our environment. Now, consider the earth moon system. We have a mirror there, that can reflect any laser beam to the earth. The orbit of the moon should be affected if the geometry works. When the moon is moving away from the center of the galaxy it should feel a braking effect. Wehn it is approaching, an accelerating effect. Over time these effects could accumulate. Contrary to the noise, the acceleration should always have a vector pointing to the Sagitarius constellation. We have extremely precise clocks, and we have even detected gravitational waves. I do not think that detecting this force is very difficult, if it can be done at all, of course. And if it is not detected, it is surely an argument againt that supposition. There many reasons that the experiment could fail. Braking effects of the tides, and many others, influences of other planets, etc. Taking all that into account is a considerable work. How big is that force? Those stars must be pulled somehow, by this attractive force, so that their rotation doesn't go down as distance increases. This force holds the galaxy together. But as distance increases, the force decreases. Nuclear force is very strong but doesn't reach very far. Gravity is much weaker but reaches farther, much farther. But gravity decreases as the square of distance, and doesn't reach as far as this new force, even feebler than gravity. But it is feasible for astronomers to catch it now, they have all the required technology. Nobody is looking however. Looking for perturbations in the orbits of the planets that point to the center of the galaxy. Mond derived a relationship M = v^4/(a0*G) to explain the Tully Fischer relationship Baryonic mass M ~ (galactic rotation v km/sec)^4 https://en.wikipedia.org/wiki/Modifi...onian_dynamics with the physically dissatisfying modified gravity explanation for an anomalous acceleration 'a0'. But assume the observed velocity dispersion represents a tangential velocity(v) around galactic center that is related to a radial velocity(vr = constant*v) that is a measure of mass inflow to the galactic center whose galactic time(t) is measured by a/v. This is dimensionally expressed as: v^2 = G*M/R = G*M/(vr*t) = G*M/(vr*vr/a) = G*M/(constant*v*constant*v/a) then M = constant^2*v^4/(a*G) with the same dimensional form as MOND but with a more physically satisfying explanation The above formula dimensionally matched to the experimental data baryonic mass M ~ (galactic rotation v km/sec)^4 for the baryonic TullyFisher relation http://arxiv.org/abs/1512.04543 figure 2 with constant ~pi indicates reasonable acceleration(a) values on the order of 10^9 cm/sec^2 and galactic times on the order of a billion years. So 'a' can be interpreted as a deceleration within galactic timeframe (t) due to a drag like force (m*a) on baryonic objects of mass m (dark matter?) m*a ~ vacuum mass density * object crossection optically unseen due to their small size and diffuse distribution. The implication is that these objects are much smaller than planets but make up most of the galactic mass(M). 
#8




Verifying
On 11/6/17 1:54 AM, Richard D. Saam wrote:
On 11/5/17 2:05 AM, Jos Bergervoet wrote: You are mistaken, people are constantly looking. Remember all the activity related to the Pioneer anomaly In reference to the Pioneer Anomaly the most definite conclusion is based on the JPL report: http://arxiv.org/abs/1204.2507 [[Mod. note  Published as Phys Rev Lett 108, 241101. The same authors' (Rutyshev et al) previous paper, arXiv:1107.2886 = Phys Rev Lett 107, 081103, is also essential reading. This reference is key; Note Figure 1 The top panel represents modeling daP/dt = k*aP model one and the bottom panel daP/dt = k*(aP  aPinfinity) model two It is clearly evident that model two predominates. The thermal modelling is discussed in more detail in Rievers et al, New J Physcs 11, 113032 http://dx.doi.org/10.1088/13672630/11/11/113032 and the same authors' (Rievers et al) later paper arXiv:1104.3985 = Annelen der Physik 523, 439 http://dx.doi.org/10.1002/andp.201100081 Presented data was below 45 AU where thermal effects predominate.  jt]] It does not reflect the thermal and Doppler solutions over time. With time, the constant Doppler solution dominates the decaying thermal solution as the Pioneers approach interstellar space. The Doppler solution is real versus the 1000s of calculated decaying internal finite element diminishing contributions. This JPL analysis failure unnecessarily negates a major contribution to science. I am not talking about new physics but a confirmation of space time. The JPL report has a geocentric/heliocentric view and dismisses the universal view. The JPL analysis is based on incomplete analysis of the data assuming the decay for Pioneer acceleration aP daP/dt = k*aP model one This fits the assumption that the thousands of analyzed aP thermal components are tied to the RTG half life with aP decay approaching zero with time. A better fit to trajectory data is the 'aPinfinity' effect as the Pioneers approached interstellar space: daP/dt = k*(aP  aPinfinity) model two Initially, as the Pioneers pass Jupiter, the thermal emission overwhelms the anomalous acceleration (aPinfinity) making it statistically insignificalt in this initial trajectory phase but diminishes with time(model one) with aP decay approaching aPinfinity with time (model two) as the Pioneers probe interstellar, intergalactic space on leaving the solar system with diminished internal thermal and external solar wind considerations previously considered. Statistically significant aPinfinity values a Pioneer 10 aPinfinity 7.0x10^10 m/sec^2 Pioneer 11 aPinfinity 8.2x10^10 m/sec^2 These values may represent a constant for interstellar medium within some standard deviation or actually represent different values based on differing Pioneer 10 and 11 directional probes of interstellar medium. The interstellar medium may not be uniform. Logically, in as much as aPinfinity is a measure of spacePioneer momentum transfer (spacetime viscosity) then all transiting object motion would be affected. This has implication for galactic and planetary system formation as reflected in accelerations associated with the Tully Fischer relationship. Apparently there is still some unpublished Pioneer data to further test this hypothesis. Considering this data's importance to the scientific community, it should be published. RDS 
#9




Verifying
On 11/9/2017 10:00 AM, jacobnavia wrote:
Le 08/11/2017 à 20:33, jacobnavia a écritÂ : Le 05/11/2017 Ã 09:05, Jos Bergervoet wrote: So you have information as to whether it is strong enough at the relatively short distances of our environment, as mentioned above? Suppose some star S at 60 thousand light years from the center of the galaxy. A normal star whose mass can be accurately determined. Its speed can be measured, and its mass is known. Then, we subtract gravity effects and we obtain the force that is necessary to accelerate that star to its observed speed at 60000 light years from the center. Supposing a roughly linear decay, here at only 30000 light years from the center we should have half of that. Looks simple but can't be that simple. I am surely missing something, but what? [[Mod. note  There are a couple of things: 1. A solartype star at a distance of 60,000 lightyears has an apparent magnitude of around 21, which is faint enough that getting a good spectrum will take a lot of bigtelescope time. We have big scopes now. Or just choose a nearer one. The farther you go, the more the discrepancyy between gravity and its observed speed should be, as we read from the speed charts of stars around the center. But all this is known already (from the smaller scopes of some years ago). We know what the rotation curves are, so the acceleration of stars on average is known, and it is known that this does not fit with the gravity of known matter in the galaxies. So you do not need the observations as you describe here to get this information. What we do *not* know is: 1) Is there more matter than the known matter, so stronger gravity and therefore restoring agreement with the movement? 2) Is there another force that adds to the effect of gravity so together they give agreement with the motion? The first possibility leads to the hunt for dark matter, the second to the search for a "fifth force". The observations with telescopes as discussed above will not help with these questions at all, they will just reproduce the already observed disagreement between motion and the gravity of known matter. Which then leaves us again with the same two questions.  Jos 
#10




Verifying
Le 10/11/2017 =C3=A0 08:10, Jos Bergervoet a =C3=A9crit=C2=A0:
We know what the rotation curves are, so the acceleration of stars on average is known, and it is known that this does not fit with the gravity of known matter in the galaxies. So you do not need the observations as you describe here to get this information. What we do *not* know is: 1) Is there more matter than the known matter, so stronger gravity and therefore restoring agreement with the movement? That would be a nice solution. And if space between the stars wasn't empty but filled with some kind of very thin gas? 2) Is there another force that adds to the effect of gravity so together they give agreement with the motion? The first possibility leads to the hunt for dark matter, the second to the search for a "fifth force". Dark matter was supposed to be in some kind of "halo" outside the galaxy. The stars then, are pulled by the outside. A fifth force would have a vector centered in the center of the milky way. Is it possible then, to figure out this from the orbit of a known star, say, the sun? The observations with telescopes as discussed above will not help with these questions at all, they will just reproduce the already observed disagreement between motion and the gravity of known matter. Which then leaves us again with the same two questions. A fifth force would perturb the orbit of the sun in a different way than matter in a halo. Besides, even if it is weak it has been there since eons. After all this time (age of the sun around 5GY) some perturbation should be observable. Shouldn't an analysis of the orbit of the sun give an answer to that? [[Mod. note  Interstellar space is indeed filled with a "very thin gas": https://en.wikipedia.org/wiki/Interstellar_medium https://en.wikipedia.org/wiki/Intracluster_medium This is already included in counts of "known matter".  jt]] 

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