Galileo

[hecd2]

What if the spacetime curvature surrounding the earth, the funnel shape we see in science museum, is actually spinning around the earth (assuming it’s something still not yet detected).

Well, wouldn’t it be detected? Things are spinning all over the place in all sorts of directions from a top in my living room, to entire galaxy clusters. Why would there be arbitrary rotations of space time in their vicinity? The theory that works, GR, predicts that the rotation of a mass causes a tiny dragging of space time in the vicinity of the mass, not some huge rotation, and that tiny dragging has been measured.

The
farther away from the body (earth), the less curvature there is, the less rotational velocity it would experience, just like in a whirlpool. Would this not bring into effect a centrifugal force which it’s direction would be towards the earth, being what we experience as gravity? A mass far away from such a body would not experience a great deal of centrifugal force, so, will simply revolve around the massive body instead.

I’m not with you here - in the toy model in the science museum, gravity arises from the curvature of space time (ie the funnel), not from the rotation of spacetime. Free-falling and orbits are fully explained by an inverse square law of gravity - the funnel. Nothing else is required.

Alec
evolutionpages.com

 

[hecd2]

hecd2:

The gunman can move however he likes, and that does not affect the trajectory of the bullet which is a straight line between the position of the gunman when he fired and you.

I would understand this in the image of a wave traveling in a medium. However, as I see it, the bullet does not make a straight line between the position where the gunman is when he shoots, and me, but would be following the gunman instead. The gunman, who is travelling, would observe the bullet as travelling in a straight line.

The bullet *will *travel in a straight line, (ignoring gravity of course), just as photons do. Why wouldn’t it? Once it’s fired there are no forces acting on it. It will have a component of velocity which it derives from the motion of the gunman, but since the gunman can point his gun in any direction, then he can compensate. In order to hit the target, the gunman has to point his gun away from the target to compensate for his movement, but the path between the gunman and the target from any given firing position is exactly the same whether the gunman is moving or at rest. You cannot tell from the arriving bullet alone whether the gunman is moving or at rest. There is only one path that joins the place where the gunman is when he fires and the target, and the bullet has to follow that path whether the gunman is moving or not.

Alec
evolutionpages.com

 

[chris_stone]

The latest views on cosmology are fascinating but how would you feel if, like Galileo, you were forced to recant them having been shown the instruments of torture?

 

[Gofer]

Sniping troll. First you ask, then you state as fact. Source?

 

[chris_stone]

This is my last posting. I was hoping for discussion and answers not violent threats (Gofer)
At least I now know how Galileo felt.
Shame on you.
Goodbye Catholic Answers

 

[mich2]

Welcome back, Alec.

I think that’s correct.
In the analogy, light always propagates through the surface of the sphere, since the third dimension is inaccessible. When it arrives, it appears to arrive from a point on the surface of the sphere closer to us than the object which emitted it actually is the time of observation.

The problem is that if the universe is bigger than the observable universe then by representing only the observable universe with a sphere we are arbitrarily creating a model where the most distant observable galaxies are on the other side of the sphere. In fact, for a universe much larger than the observable universe, then the galaxies on the edge of observation (at the time they emitted the light) would form a circle centred on us about 13 billion light years away. (In the real 3-D universe we see the furthest observable galaxies on a sphere centred on us with a radius of about 13 billion light years.

This 3D model would be my prefered one to go with, Alec. It puts the observer central to the universe making the universe expand in every direction beyond. We can also claim this frame of reference to be equally good for any observer within the universe. However, as was said by Stephen Hawkins and others, this has not been proven

lanl.arxiv.org/abs/0807.1443

No galaxies are closer to the Big Bang than any others. The Big Bang pervades the whole universe and is present everywhere.

However we could also claim that any observer within the universe would observe the same.

The space time is curved as a consequence of the presence of the mass. If the mass is moved then the curvature moves with it. In order to move the mass we need to exert a force, sure, but having exerted that force, the acceleration of the mass returns to zero, but its velocity is different from before and will remain at the new value until another force is exerted.

True; and this new velocity, which doesn’t actually need to be relative to anything, would give rise to a new dynamism of spacetime extending outwards in all directions from the source, at the speed of light.

Are you trying to explain inertia by suggesting that space time has some sort of viscosity? I don’t think anyone knows for sure at the moment, but one theoretical possibility is the influence of the Higgs field, which is a bit like adding viscosity to spacetime (although I don’t think that the curvature of spacetime in the Higgs model lags the position of the mass as you suggested), so I think your idea is quite insightful.

Alec
evolutionpages.com

I would not however identify spacetime as separate from the mass, as in a mass moving within a medium. I would rather see it more as an extention of the mass energy itself.

Andre

 

[mich2]

Well, wouldn’t it be detected? Things are spinning all over the place in all sorts of directions from a top in my living room, to entire galaxy clusters. Why would there be arbitrary rotations of space time in their vicinity? The theory that works, GR, predicts that the rotation of a mass causes a tiny dragging of space time in the vicinity of the mass, not some huge rotation, and that tiny dragging has been measured.
I’m not with you here - in the toy model in the science museum, gravity arises from the curvature of space time (ie the funnel), not from the rotation of spacetime. Free-falling and orbits are fully explained by an inverse square law of gravity - the funnel. Nothing else is required.

Alec
evolutionpages.com

I’m only playing with an idea, due to most of the planets revolving around the sun in the same direction. I tend to find Mach’s principle rather attractive, in that while we could speak of Newtonian type of laws of motion, such as the conservation of angular momentum,I have an itch which tells me that such laws might be controlled, if not caused by the fabric of spacetime. Here’s a link which I found somewhat interesting.

matpitka.blogspot.com/2008/03/dark-matter-based-model-of-flyby.html

Andre

 

[mich2]

The bullet *will *travel in a straight line, (ignoring gravity of course), just as photons do. Why wouldn’t it? Once it’s fired there are no forces acting on it. It will have a component of velocity which it derives from the motion of the gunman, but since the gunman can point his gun in any direction, then he can compensate. In order to hit the target, the gunman has to point his gun away from the target to compensate for his movement, but the path between the gunman and the target from any given firing position is exactly the same whether the gunman is moving or at rest. You cannot tell from the arriving bullet alone whether the gunman is moving or at rest. There is only one path that joins the place where the gunman is when he fires and the target, and the bullet has to follow that path whether the gunman is moving or not.

Alec
evolutionpages.com

After having read your explanations, I believe that I have it now,Alec. Thanks. However, I still believe the source will cause an abberation,but it’s not something we would be able to detect. Here’s the way I see it.
To calculate the abberation, the length of the telescope is needed.
Therefore, the change in the movement of the earth can be detected
through the abberation of the stars.
Now, let’s say that we had a telescope that was so long as to reach the star. In order to properly adjust the telescope to allow for the path of light to reach the observer,one would need to consider both the earth and star’s velocity. From this, my deduction would be that the abberation of the lights coming from the stars in the universe are simply what we would identify as being the observable universe, while the true position would be that of the universe in real time, this being unobservable.
If what I’ve written makes sense, then, I believe that I do now understand, thanks to you.
Having said this, I would now need to explain the link below.

arxiv.org/abs/physics/0401090

Andre

 

[Gofer]

This is my last posting. I was hoping for discussion and answers not violent threats (Gofer)
At least I now know how Galileo felt.
Shame on you.
Goodbye Catholic Answers

See, I proved my point. Then why not provide a source for your contention that he was shown the instruments of torture? In the first post you ask if this is true, others have also asked for sources, you give none but pop up again and assert he was! TROLL!

 

[missal]

This is my last posting. I was hoping for discussion and answers not violent threats (Gofer)
At least I now know how Galileo felt.
Shame on you.
Goodbye Catholic Answers

Hi,
You really shouldn’t let fools prevent you from enjoying this forum. Like any place else,
your always going to bump into idiots.
From what I gleaned from old text books, Galileo was one of many scientists on the cutting edge then. It was the school which the Church wanted Galileo to renounce, which did not attribute creation to God.
Origen allowed that the sun, moon and stars were endowed with life and intelligence. A view for which he was later condemned according to the minutes of the Second Council of Constantinopole (AD 553) You see, there was a notion that mute creatures exhibited a form of intelligence …disregarding the integrity of all God’s creatures. There were lots of these types of schoolings questioning the principle of inertia, and if the universe moved in accordance with the command of God.
Here’s a good book on the subject of these scientists: “Creation and the History of Science”, author Christopher Kaiser ----check out page 126 which covers Galileo.
Hope that helps
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