gravitons

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Do you have a theory that you personally favour? Or do you think it's all BS?
I really hope they are totally wrong, myself. Not because I have a problem with the physics - I don't know the answer, but I just prefer it when the whole flocking lot of them are wrong.

So far General Theory of Relativity works fine for gravitation and the Standard Model works for the other forces. Hey! It's close enough for government work.

ruveyn

So far. But I know there is something that does not add up, and it will matter more and more as we go further into space. I remember it being clearly said in one of my classes that sometimes things in space don't move as they are supposed to.I don't remember exactly what, just that sometimes calculations don't work out, and they don't know why. Whether there is an influence from hidden matter, or 'dark energy' or maybe some sort of ripple in the 'fabric of space', or maybe just not enough sig figs in G, I know not. Aliens, maybe?

The motion curves for stars in the outer portion of galaxies do not have Keplarian motion. Franz Zwicky came up with this back in the 1930's but he was such an ugly guy with a bad temper no one listened to him. Eventually people did catch on to what Zwicky was saying. Now we have Dark Matter to "explain" why galaxies behave like rigid disk merry go rounds.

ruveyn

And I think dark energy and dark matter look like grasping at straws, when you look at them from the right angle. But again, I can't say they are wrong. Part of the fun of trying to understand something the size of the universe, from a point as tiny as the Earth.
But I was referring to something much smaller scale and local. Apparently there are actual problems with the predicted motion of our space craft through our solar system. I wish I had details to offer you, we weren't given any at the time, but I do recall the phrase, "it's causing serious problems".

There was some odd behavior with spacecraft nearing the edge of the solar system - the Pioneer 10 and 11 probes, in particular, seemed to be decelerating as they neared the edge of the solar system. Many hypotheses were propounded to explain this, from dark energy to expansion of space within the solar system (at a far more rapid pace than predicted by the Big Bang theory). After investigating the available data for over a decade, however, Slava Turyshev et al. have published an article in Physical Review Letters demonstrating that the anomaly is fully explained by thermal radiation from the spacecraft itself, emitting sufficient infrared photons ahead of the craft to slow it infinitesimally (a matter of thousands of miles difference in expected position over a several-billion-mile course).

There's also a new discovery complicating the whole "dark matter" hypothesis - the discovery that the majority of objects orbiting our Milky Way galaxy are in a single plane, at approximately right angles to the plane of the galaxy itself. Current hypothesis to explain this is that about 11 billion years ago the Milky Way collided with another galaxy, stripping it of some of its halo objects; the difficulty there is that this would seem to argue against the idea that galaxies form around clusters of dark matter. Astrophysics is in a very interesting place just now...

[quote="DeaconBlues"
There was some odd behavior with spacecraft nearing the edge of the solar system - the Pioneer 10 and 11 probes,.[/quote]

That could have been equipment problems. The way to resolve this is to send probes with different machinery to see if the same effect is observed.

ruveyn

Concerning the 'pressure from everywhere but shielded by mass' therory.

On the local level in our solar system I would wonder how the shielding effect would work with planetary alignments.

An alignment happened fairly recently that all the plantes were in a line from mercury to uranus. Variations is strength and scattering of gravity's effects down line were not noted during this event.

A theory involving matter to be opaque to gravity would have to include both gravity shadows as well as gravity tunnels that are unobserved as yet. Don't know if we are looking for them or not. Odd motions of spacecraft at the edge may be what we should look at?

I tend towards using empirical information rather than math for this.
I have examined a proof where it was shown certain particles emerging from black holes were in reality particles falling INTO the black hole, but because of reverse time we observe them as coming OUT. Scientific American many years ago has the full story.
On a personal level I find this absurd, on a math level it makes sense.

I like math, but as the mathmatically functional string theories demonstrate, only one can be correct but all check out mathwise.

All the planets and asteroids added up together account for less than one percent of the total mass. Planetary alignment contributes bupkis, zilch, nearly nothing the gravitational stresses.

ruveyn

Yeah, about a tenth-ish of a percent. But do they gave a guestimate for the total mass of the oort cloud or even the kuiper belt? Just wondering, because it could make the planets even more paltry looking.

Like I said before, I'm pretty sure the pressure thing would have the same resulting effect as attractive gravity, so if you could not measure it one way, you could not measure it the other way either. The only question is, is it pushing or pulling?

The Kuyper Belt and the Oort Cloud are diffusely spread in volume both above and below the plane of the ecliptic. As a result the gravitational forces they exert pretty well cancel them selves out.

ruveyn

RE the colliding galaxy theory -

I think maybe if a small disc shaped galaxy collided with the milky way at an angle perpendicular to our disc, the gravitational interactions would for the most part leave the mass distribution in the same 2 planes. But the small disc would become more spread out, and how much would depend its original velocity at the time of the collision.

And if this were true, then I would be very interested to know about what happened to the supermassive black holes. A collision would be extremely unlikely, so it might still be there somewhere.

Maybe at the edge of our solar system? Making our spacecraft go funny?
THAT WAS A JOKE PEOPLE!! !

But it would certainly be making any stars around it act funny.

I actually never looked into it, but the hasn't Milky Way has had at least one collision before? I would expect that every galaxy has a SMBH in it's core. So anyone know of any floaty SMBH's in our galaxy? Any stars not quite following the crowd?
I wonder how many galaxies out there have more than one SMBH in them?

A Long Time Ago.

ruveyn

Actually I was thinking about the relative proportions of mass of various objects in our solar system. Just how massive are the Kuiper belt and the Oort cloud?
But, the Kuiper belt would only cancel out in certain planes relative to the ecliptic. But if it's not that massive, it would make no difference, especially since its so far away.
Pretty sure it would be negligible, either way.

But the SMBH would still be there somewhere. The only way it could disappear is if merged with the Milky Ways', one. Or if it got flung out, but it would take some stars with it, and maybe over time would evolve to look like another galaxy. Ok, I'm just wildly speculating here.
Better go have breakfast. It's 1pm here

Have a G'day mate.

ruveyn