Making Earth the Center of the Solar System

[lodestar]

If we assume the center of mass of the whole unverse is the earth. If we now enter the sun into the system, it will orbit around the center of mass, hence around the earth. If we now enter neptun into the system, it should also orbit around the center of mass, hence around the earth. Why is it, that neptune instead chooses to revolve around the sun.

In the same way that in the heliocentric model each planet orbits the Sun, while the Sun orbits the center of galaxy and carries the whole Solar System with it. The issue is just relative movement. The larger encompassing system doesn't change the relative movement within the inner system.

There is no significant difference between neptun and the sun. Yes, the sun is much heavier, but it would't matter in comparison to the center of mass of the whole universe, would it? To make that argument work, not only the earth should be in the center, but the sun has to be truly special.

Not at all, pretty much like the center of the milky way has nothing special, yet, all stars and planets within it still revolve around it while keeping their orbits in the local systems.

But let us assume the the issue of movement isn't relevant in this discussion, as you said.

It's not an assumption. It's a fact. Relative movement is irrelevant on this matter. The math works for any place you choose.

Than one can't use this argument to promote geocentrism either, just counter some conter-arguments. So there has to be another reason to assume the earth is the center.

Sure, one can't use this argument to promote geocentrism, but one can use it to say it's as valid as other models, and then there are other arguments to prefer one model over the other. For instance, you can say Ockham's Razor favors the geocentric model, since it doesn't need the assumption that the distribution of matter in the universe is uniform.

Observations of the universe outside our solar system could theoretically point to the conclusion, that the earth is the center. But since the stars are so distant, one would make nearly the same observations about redshift, parallax, etc. from any other planet of the solar system. So that oberservations can not be used to argue for geocentrism either, it could just narrow the center of the universe down to a point in our system. Since that covers ALL oberservations from the sky, there is nothing there to support the claim of geocentrism. But you claim that there are such observations:

No observations of relative movement anywhere else in the universe made from or close to the Earth could support one model or another, because ultimately they all depend on the assumption of the cosmological principle. However, there are observations for which the geocentric model provides better explanation than a frame-independent model.

So you can only refer to 'introspective' observations, like the Michelson-Morley-experiment. Would you agree with me, thats the only kind of observation that could possibly point to a earth centerd universe? If not, please ellaborate why . If yes, than we all know that we don't have to discuss cosmical observations anymore, but can concentrate on such 'introspective' observations.

The problem isn't that some observations point to an Earth centered universe. The problem is whether that is acceptable on non-scientific grounds. For instance, I mentioned quasar distribution before. All known quasars are distributed in groups of concentric spheres around the Earth. That's obvious if the Earth is at the center of the observable universe, but that's not an acceptable solution for modern astrophysicists due to their commitment to the Cosmological Principle. To this day, as far as I know, that is an unsolved problem. There's no solution that works without breaking with the Cosmological Principle or introducing even worse assumptions.

Edited February 2, 2014 by lodestar

[Brotoro]

Ah. K^2 gets it said faster because he is more succinct.

[lodestar]

You've claimed that dark matter is not necessary, because General Relativity is wrong.

I never made that claim. Quite the opposite. I said that if General Relativity is correct, then Dark Matter is a necessary fudge factor to get the math to work for current observations, but that looks a lot like a reductio ad absurdum to me.

Now you are back to claiming that GR is correct, it's just not the only correct model. If an alternative model is equivalent to General Relativity in your chosen frame, then it will make all the same predictions, including dark matter.

I never made any claim to the correctness of anything either. Quite the opposite. I'm saying neither model can be proven correct and they are scientifically equivalent. The choice between them rests on philosophical premises, not scientific grounds.

If you keep reading things I never wrote, we'll have a hard time understanding each other.

And yeah, you can pick Earth as the center of your coordinate system, then warp things about with "density" variations until time flow is consistent with General Relativity. Guess what? You've just went and constructed a special case of the manifold which is generally described from perspective of relativity. You haven't solved any problems. Just created a bunch of new ones. And even then, you still end up with galaxies having way more mass than they should based on luminous matter.

That's absolutely wrong, because I'm not talking of geocentric coordinates in the same frame-independent model. I'm talking of another model with a preferred reference frame.

Now, if you don't feel embarrassed about saying dumb stuff like that, that's unfortunate, but it's your right. But please, do it somewhere else. This is a science section, and we have certain standards around here.

So far, you haven't managed to refute anything I actually said, only things you imagined I said, as this post confirmed, and you failed to even acknowledge what I'm talking about. To claim I'm saying dumb stuff doesn't mean much when this very last message confirms you still don't understand what I'm talking about. Trying to pretend superiority or arrogance after your failure doesn't help your case much.

I assume this board has a moderator. If my posts don't meet the standards, complain to them.

Edited February 2, 2014 by lodestar

[lodestar]

I can write a system of equations and physical laws based upon the assumption that my head is the center of the universe. This simply makes sense, of course, because all of the observations I have of the universe are based on what comes into my head. My head always stays perfectly still. As my mighty legs move, the Earth rolls underneath my stationary body. When I want to look off to the side, my head, of course, stays stationary while you and the rest of the objects in the universe rapidly zip through 90-degree arcs. Sure, I can do that.

Sure, you can do that within a frame-independent model, but as I just tried to explain to K^2, I'm not talking of the equal validity of any coordinate system within a frame-independent model, but the equal validity of an absolute model with a preferred frame of reference and a frame-independent model. All in all, what I'm saying, and I usually assume all physicists and even students know that, is that you don't need General Relativity if you put the Earth in the center. Maybe you missed that class...

[ZetaX]

All in all, what I'm saying, and I usually assume all physicists and even students know that, is that you don't need General Relativity if you put the Earth in the center. Maybe you missed that class...

Finally give a reliable source for that!

[TheDarkStar]

One note - unlike what you said, the stars in the galaxy actually are orbiting something. We can figure out its mass based on this. It's not just a common barycenter; there's a real object (and it is almost certainly a black hole).

Also, it's not correct to say that a frame-independent model and a frame-dependent model are the same. In a frame-independent model, lightspeed can be apparently different if you accelerate. In a frame-dependent model, it's the same for every observer no matter their relative velocity to any other observer.

[lodestar]

One note - unlike what you said, the stars in the galaxy actually are orbiting something. We can figure out its mass based on this. It's not just a common barycenter; there's a real object (and it is almost certainly a black hole).

Sure, but that's not a requisite. The barycenter doesn't have to be within any object, for instance, in a binary system, where both bodies orbit a common point in empty space

Also, it's not correct to say that a frame-independent model and a frame-dependent model are the same. In a frame-independent model, lightspeed can be apparently different if you accelerate. In a frame-dependent model, it's the same for every observer no matter their relative velocity to any other observer.

I'm not saying they are the same. I'm saying they may be equally valid, both providing explanations to observed phenomena, and choosing one over another may not depend on scientific grounds.

[TheDarkStar]

I'm not saying they are the same. I'm saying they may be equally valid, both providing explanations to observed phenomena, and choosing one over another may not depend on scientific grounds.

That's the problem, though - a relative speed of light is not consistent with observed events. For example, the orbit of Mercury is significantly different than Newton's laws predict, but relativity fits the orbit almost exactly (the deviation is accounted for in the slight pulls from all the other objects in the solar system).

[Vanamonde]

While this is an interesting discussion, the argument has become heated to the point that members are attacking each other rather than addressing each others' ideas. Please remember that we are all fellow KSP players here, and turn your energies to other discussions for a time. Thread closed.