Problems with the Heliocentric Model
« on: May 20, 2019, 11:19:44 PM »
Last summer, I had a thread where I asked for genuine questions about how things work with the standard mainstream model of RET. I'd like to open that topic up once more.

Is there something about garden-variety RET that seems wrong? Something that was never adequately explained? I'd love to help you science anything.

Motion of Sun, Moon, & Stars? Phases of the Moon? Eclipses? Does the horizon rise to eye level? How does the curve calculator work? Does the curve calculator work? What's a gyrocompass? What the heck is the "spacetime metric?" Anything you like.

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Offline Tim Alphabeaver

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Re: Problems with the Heliocentric Model
« Reply #1 on: May 21, 2019, 08:05:11 AM »
Since you mentioned it, what the heck is a spacetime metric?
**I move away from the infinite flat plane to breathe in

Re: Problems with the Heliocentric Model
« Reply #2 on: May 21, 2019, 10:35:00 PM »
Since you mentioned it, what the heck is a spacetime metric?
First of all, nice chinchilla.   :)

The full explanation of the spacetime metric is VERY mathy. Let me try to summarize a bit.
The full form of Einstein's general relativity equation looks like... erm I have no idea how to do equations in this...
So it's this equation with something typically written as "g sub uv" on the left and "T sub uv" on the right.
We call the "T sub uv" the "stress tensor" and the "g sub uv" is the "spacetime metric" or just the "metric".

What the what now?

Very loosely, that stuff on the right-hand side represents the mass and energy in the system. The stuff on the left describes the movement of objects in space and time. Put very simply, if you can count up all the energy in a region of space and put it on the right-hand side of that equation, the left-hand side will tell you how everything in that region should move.

Going just a little deeper, the "spacetime metric" part of the equation describes the shape of space and time... and once again the what now?

There are 2 ways of looking at this...

1) The spacetime metric describes how objects move. We understand that objects in a gravity well are pulled towards the center of that gravity. This equation describes how the object's position in the future is affected by gravity.
2) The spacetime metric describes how space and time are actually curved so that an object moving in what appears to be a straight line from the object's perspective is curved to a perspective somewhere else.

That number 2 there is bizarre.  I'm about to dig a little deeper into the math, so just quit reading wherever you get bored...

What's a "vector"? Let's describe motion in 2D. We'll call the direction from West to East the "x axis". We'll call South to North the "y axis". You can describe your position and velocity as some combination of x and y. So bundle the x and the y together and call them a "vector." Your velocity can be thought of as a single value v. We understand that v has an x component and a y component, and together v.x and v.y are collectively known as v. Simple. Add altitude and we have a 3D vector. There you go... 3D space.

How does time fit in? At some time t=t0, you were at location p0 (a vector in 3D space). At some later time t=t1, you had moved to position p1. We could add t to our bundle of data to make the 4D vector (p.x, p.y, p.z, p.t). Now we can put that together like so: (p0.x, p0.y, p0.z, t0) or maybe we'd just call that (p0.x, p0,y, p0.z, p0.t)... collectively p0 as a 4D vector.

Why? Honestly, let's just start with "Why not?" We can do this if we want, so we did it. Justification not needed. It's a mathematical abstraction.

We now have a 4D coordinate space... "spacetime". Space and time combined into a single mathematical abstraction. Simple as that.

Einstein was struggling with how to resolve relativity (now known as "special relativity") and gravity. He started with what we call the "equivalence principle." This states that acceleration due to gravity feels EXACTLY like the inertial force you feel under acceleration. Putting that another way, free-fall feels EXACTLY like zero-g.

When he combined this with the Lorentz transforms of special relativity, this didn't make any sense. How can light not tell the difference between an accelerating frame and a gravity well?

Through a lot of hard work and some pretty heavy math, he eventually realized that if you describe the world using 4D coordinates "spacetime", AND you allow for the "spacetime" to be curved arbitrarily, the paradox can be resolved.

Einstein described the equations of motion using 4D spacetime. The radical part comes in when we allow for what we consider to be the "x direction" (remember that was East) to vary. At any given place and time, x is fixed pointing East. But what if at some other location or time, x could point in some other direction? Remember how we said our 4D axis was (East, North, Altitude, Time)? To picture this, imagine your East, North, Altitude axes on a globe (or on an AE projection if you prefer). The direction of "East" is different at different locations. If you keep going East, you'll eventually get back where you started from. Einstein's equations allowed for this exact situation. He started with an arbitrary 4D coordinate system to describe "spacetime". He didn't decide up front that x must point East. Instead he solved the equations and allowed the equations to tell HIM which way the x axis pointed.

Does that make any sense? Einstein abstracted away the coordinate system in which he described the forces and motions. He constrained this equation with what we knew about the physical universe and used that to solve for what the coordinate system looked like. THAT is the "spacetime metric". That's what the coordinate system looks like based on the way the universe behaves.

What'd we discover? What we see is that the presence of a point-mass on the right-hand side of the equation (a high density energy), the coordinate system becomes curved. That really shouldn't sound all that shocking at this point. After all, we invented our coordinate system with North, East, and Up in the first place right? And we know that ended up being curved, so why shouldn't the "spacetime metric" end up curved too?

What's really interesting about this curved spacetime metric is what happens if we place a small, stationary object in space near a point mass. If we solve for the future location of our stationary object, we see that it will have moved towards the point mass. If we put in a small value for the point mass, the solution for the future location of our object precisely matches Newton's universal law of gravitation. Only this time, we don't get there using F=mA. We get there just by solving the 4D coordinate system. Neat right?

So what? Well, what if instead of a stationary object, we put a beam of light next to our point mass? Prior to 1915, we had no reason to expect that gravity affected light, but this new "spacetime metric" gave the same solution for light that it did for matter - the light should bend towards the point mass. This was an unexpected prediction made by this new equation, and in 1919 that prediction was confirmed to be accurate. We now know that light is affected by gravity.

There are several other very surprising results that fall out of this equation, and one by one, each one has been confirmed. We know this equation must still be incomplete in some small way, and theoretical physicists and mathematicians are in a race to the next major breakthrough.

Summary: The "spacetime metric" is the part of Einstein's field equations (general relativity) that describe how an object moves through space. We usually describe this as time and space being curved, but to be precise, we're really talking about the motion of an object that is curved in space and time. Is it the motion that's curved or spacetime that's curved? That's sort of a philosophical question really. We can be certain that the math says the thing's gonna curve, and on that we can all agree.

But is this all theoretical? I mean, it's just math right? Many times, the math can give us new insights into the behavior of the physical world, and this is the perfect example. The math said that light should bend, and guess what... now that we knew to look for it, we were able to show that light DOES bend. The math says time passes differently in the presence of gravity, and guess what... it does! We don't just take the math and say, "oh well... math says it's true so I guess we'll just accept it." No, we look at the math and say, "according to this math, this should be true... let's see if we can test that!" The math has taught us a lot about the realities of the physical world... it shows us what to look for.
« Last Edit: May 21, 2019, 10:42:26 PM by ICanScienceThat »

Re: Problems with the Heliocentric Model
« Reply #3 on: May 22, 2019, 07:59:00 AM »
Hmm, well yes of course.
It could be round or flat, but round has really been working out so much better for us.

Perhaps it would be better to say the Earth is "pointy".

Re: Problems with the Heliocentric Model
« Reply #4 on: May 23, 2019, 10:41:09 PM »
The "spacetime metric" is a pretty complex topic. The super-short version is, "Einstein figured out that space and time are related, and oh, by the way, they are both curved." But naturally, that simple statement earns nothing but scoffs from all over the science spectrum.

A better description is, "Einstein did some math that said time and space can bend. We checked it, and it turns out his equations work really well to describe reality." But that still leaves most readers pondering what the hell bent space or bent time even means.

So I prefer, "Einstein did some math. In his equations, we have a term we call the 'spacetime metric.' This thing describes the way stuff moves through space. The equations predict what we all know of as gravity."

Is that any better?

Any other requests out there?

Re: Problems with the Heliocentric Model
« Reply #5 on: May 24, 2019, 09:53:46 AM »
No, I thought your spacetime metric explanation was real good. Not to say I understand it 100%. I have an ok grasp of it though.
It could be round or flat, but round has really been working out so much better for us.

Perhaps it would be better to say the Earth is "pointy".

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Offline Tom Bishop

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Re: Problems with the Heliocentric Model
« Reply #6 on: May 25, 2019, 03:51:25 AM »
There are no "problems" with the heliocentric model because it is composed of hundreds of years of a concentrated effort to construct confutations to explain why things are not as they seem.

Any motionless earth experiments are explained with length shortening, changes to the understanding of space and time, anything it takes.

A situation where the most sensitive experiments created by science are unable to detect the gravitational influence of the sun or moon? Easily explained by selective gravity; "preferred curves" in space-time, which the test bodies in the experiments are following.
« Last Edit: May 25, 2019, 03:53:09 AM by Tom Bishop »

Re: Problems with the Heliocentric Model
« Reply #7 on: May 25, 2019, 03:58:15 AM »
There are no "problems" with the heliocentric model because it is composed of hundreds of years of a concentrated effort to construct confutations to explain why things are not as they seem.

Any motionless earth experiments are explained with length shortening, changes to the understanding of space and time, anything it takes.

A situation where the most sensitive experiments created by science are unable to detect the gravitational influence of the sun or moon? Easily explained by selective gravity; "preferred curves" in space-time, which the test bodies in the experiments are following.

Tom, is there anything in there that you'd like me to address? My assessment is that this post is not a request for any explanations.

Happy to address any genuine questions. No matter who they come from. Not going to argue anything, but if anyone wants an explanation, I'll do my best.

Offline iamcpc

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Re: Problems with the Heliocentric Model
« Reply #8 on: May 28, 2019, 04:53:00 PM »
There are no "problems" with the heliocentric model because it is composed of hundreds of years of a concentrated effort to construct confutations to explain why things are not as they seem.


Seriously Tom? If there are no problems with that model then why is the community so fragmented with dozens, if not hundreds of different models?

I'll give you a hint:

Some models do very well at explaining some things while other models do well at explaining others. Every model has problems that's why alternate models are being made.

Re: Problems with the Heliocentric Model
« Reply #9 on: June 05, 2019, 03:30:05 PM »
There are no "problems" with the heliocentric model because it is composed of hundreds of years of a concentrated effort to construct confutations to explain why things are not as they seem.
That's somewhat of a misrepresentation, Tom.
Scientific models simply get updated or replaced as we learn more.

For centuries the geocentric model ruled the roost. It does a very good job of explaining the path of the sun and stars, it does look like we're at the centre of things. It wasn't till 1534 that Copernicus published his book advocating the heliocentric model based on the way the planets move and it took quite a long time for that to be accepted. For quite a while attempts were made to make the geocentric model work, so ingrained was it. Ultimately though, the heliocentric model just works better and more accurately matches observations.

Similarly, Newton's model of gravity and motion was thought to be the definitive model for a long time, some of the findings a century or so ago didn't work well with that model and that's when Relativity entered the fray. That's more of an amendment to Newton than a complete replacement in that at "normal" speeds the equations reduce to Newton's, but it does more completely explain observations.

This is how science work. It's weird that you sneer at this and regard it all as fudges when your model has lots of things like this - the sun's consistent angular size is explained by a fudge where randomly some objects maintain the same size regardless of distance. There are lots of examples in your model. And you're very scathing of science in general but cherry pick bits of it like Special Relativity to explain why in UA we don't go past the speed of light. I'm not sure why the speed of light needs to be a universal speed limit in your model.

Most of your problems with the heliocentric model are you just not understanding it properly, like the recent one about shadow direction in an eclipse. And admittedly that does take some thinking about but if you take the trouble to you'll see that these problems don't really exist.
If you are making your claim without evidence then we can discard it without evidence.