Oh my. Where to begin?

Dr. Brown wishes to make the solar system ~1% more massive so that ISON will no longer be hyperbolic. He needs to have this extra mass distributed in a hollow sphere around the observable solar system so that ISON only ‘feels’ its pull when it is out beyond the spherical shell, and not while inside it, and also so that the orbits of the known planets are not noticeably perturbed. 1% of the mass of the solar system would represent about 10 times the combined mass of all the moons and planets, or about 3000 times the mass of Earth. The Oort cloud that Dr. Brown dismisses is theorized to have a total mass of somewhere between 5 and 100 Earth masses. So Dr. Brown wishes to replace the unobserved Oort cloud with an unobserved cloud having up to 600 times _more_ mass in it – and yet the Oort cloud is supposed to be the fantastic claim?

At the time of this writing, ISON most definitely feels the pull of gravity of all of “the planets, satellites, or asteroids”. These effects are of course swamped by the pull from the Sun – inverse square law and all that – but the pull from the other masses in the solar system does not stop when the comet is inside their respective orbits. The Moon doesn’t fly off into space when it passes between Earth and the Sun, does it? The phenomenon that you are claiming only applies to the interiors of hollow spherical shells of matter, not to orbiting planets.

As for hitting bullseyes from Proxima Centauri, it’s not surprising that objects moving toward the solar system are attracted toward the spot where 99.6% of the mass in the solar system is located. ISON is behaving almost exactly as it would if it was in free fall toward the solar system from a large distance away.

If this is the comet of 1680, it’s coming back about nine _thousand_ years earlier than expected. How much mass does Dr. Brown have to put out beyond the solar system to cause that comet, or a portion of it, to perform such an abrupt about-face? Does Dr. Brown find it less unlikely that a random flyby of a massive trans-Neptune object caused all or a portion of the 1680 comet to whip around and come back into the solar system along approximately the same track that it followed initially (when it should be about 200 AU out at the moment)? Forget bullseyes from Tau Ceti – this is like shooting a bullet at the sky and having it ricochet off a falling meteor and come screaming back straight down the barrel of your gun!

If this is the level of your understanding of gravitational effects, no wonder you don’t see the holes in Dr. Brown’s theories.

The gravity of a toroidal distribution of mass, or of a flat disk with a hole in it, does not behave like you think it does. From a very large relative distance – many times the outer radius of the disk or toroid – it does behave like a point mass at the center of the disk or torus. But as you approach, this behavior breaks down. For objects inside the torus, or in the hole of the disk, the net gravitational force is toward the plane of the disk and _away_ from the central point, not toward it. There is an unstable point at the very center of the hole where there is no net force in any direction, but if you stray from that point you are pulled toward whatever inner edge of the ring or disk is closest. See link to mathpages.com if you don’t believe me. This is different from the case of a hollow spherical shell. If you are crossing the disk within a few radii you will be pulled down toward it and if you are at/in the hole you will be drawn _away_ from the axis of the disk (if there is a star in the middle of the disk it will be pulling you toward the center point, but that will be opposed by the pull of the mass of the disk). If there hole contains a sun and associated planets, the orbits of the planets will be affected by the mass in the disk/torus.

ISON always feels the Earth pulling ISON toward Earth, no matter where the other masses in the Solar System are. When ISON is grazing the sun it feels a small force component directed toward Earth, and when it is out past Pluto it feels a (smaller) force component directed toward Earth. If it by chance passes _very_ close to Earth on the way in or out, the Earthward force vector may briefly become the largest component contributing to the comet’s net acceleration because gravity is an inverse square force, in which case we would see a slingshot effect and the orbit would be changed. Why would a close flyby of Earth redirect ISON’s orbit if Earth’s gravitational contribution was somehow oriented only toward the barycenter of the Solar Sytem? When we send a space probe zipping out to Jupiter to pick up speed and a new heading in a slingshot maneuver, how do you think that works? Does the probe experience no gravitational force from Jupiter until after it is outside Jupiter’s orbit, and even then only from Jupiter’s contribution to the overall barycenter of the solar system? The answers to those last two are both no, by the way.

Feel free to assume that there is a large amount of material out beyond Neptune. Just realize that if you assume 600 times the mass of the Oort cloud on one hand and pooh-pooh the Oort cloud on the other hand, you appear inconsistent.

The inclination of the orbit does not matter; what matters is that you think a single flyby encounter with a massive trans-Neptune object can warp an elliptical orbit with a period of >9000 years into one with a period of 300 years but which somehow follows the incoming limb of the original 9000-year orbit while actually being hyperbolic. Or something. It’s easy enough to prove me wrong, of course – just show where and how large such a mass must be to have the desired effect on ISON’s orbit. I doubt that you could get the job done without a Sun-sized object in the plane of the ecliptic out around Pluto, but I’d be pleasantly surprised to be proved wrong.

It is disappointing, although not surprising, that Dr. Brown’s claims (or are they yours?) are publicized here before any foundational supporting work has been done. ‘ISON is 1680’, we are told, ‘redirected back to the inner Solar System by gravitational interaction with trans-Neptunian masses’. How much mass? In what distribution? Why has this mass not affected the orbits of Neptune or Pluto or the long-period comets or the Voyagers? What path did 1680/ISON follow that allowed it to come back in so close to its original route despite not following any kind of regular elliptical orbit? It seems that this has not been worked out at all, and it probably won’t ever be. Why bother when the bald claim supports the narrative so well, and so few will actually know enough about physics to see the holes?

It does match a pattern in Dr. Brown’s work in which ad hoc justifications are given without supporting models, calculations, or evidence. The Solar System’s mass has been underestimated by ~1%, because that would push ISON’s orbit from hyperbolic to elliptical. The fountains of the deep jetted up at 11km/sec because that is the escape velocity of Earth and any lower value would invalidate the comet origin hypothesis (or is it 42 km/sec, the escape velocity of the Sun at the distance of Earth’s orbit? You imply that some material was launched on hyperbolic trajectories right out of the Solar System). The temperature of the subterranean cavity was a given value because that is how hot certain meterorites must have been in the past to form their particular features, and if it was not so hot they could not have come from Earth during the Flood. The Earth rolled 34-45 degrees on its axis in order to put mammoths in high latitude locations – no explanation of how this happened is offered. Ice and mud in decaying orbits fell as catastrophic amounts of supercold snow rather than exploding into superheated plasma or producing millions of impact craters, because something is needed to freeze the mammoths. Where did the heat of reentry go? No explanation. Etc., etc.