Astronomy and the quran

[karrie]

eanassir.

You can not leave the moon's position in relation to the sun out of the equation.

The entire solar system is just that, a SOLAR system. The earth is not the center of it, and is not the basis by which the rotations of celestial bodies are measured. They are measured by drawing an imaginary fixed point, (ie, the center of the sun) and then watching the dance of the planets and satellites, while holding that point still. Because we are moving too, we can not assume that simply because something is facing us constantly, it is not moving as well. It would be like driving down the highway, and assuming that the car in front of you had stopped, merely because it was maintaining a constant distance from you.

 

[Dexter Sinister]

About the Moon: it does not rotate around its axis

Yes it does, it rotates once in the same time it takes to make one orbit of the earth. Your example with the rigid rod between two balls only proves the point that you think it refutes. You have failed to grasp the most elementary facts of orbital mechanics because you insist on viewing them through the filter of religious texts, which are not a useful guide to empirical facts. You have no real understanding of what you're talking about, you are simply and completely wrong.

Let's try another example here, because I think you're having a problem understanding different frames of reference. Suppose you have a cat, you grab it by the tail and twirl it around horizontally over your head.* Is the cat rotating around its axis? Consider what the cat would see and feel. It would see the environment whirling around it, and it would feel a centrifugal force directed horizontally outward parallel to its spine and an oppositely directed centripetal force inward pulling the other way. The cat would certainly detect that it's rotating and that it's experiencing forces that are trying to stretch it parallel to its spine. The effect on the cat is exactly the same as it would be if it were spinning around an axis vertical to its spine at the point where you've gripped its tail. And it's exactly the same because that's exactly what's happening, the cat is rotating around that axis. The axis is also rotating around your hand at the same frequency, so the cat's bum constantly faces your hand, but that doesn't mean the cat's not rotating.



*I use a cat as the example because I don't like cats much and there are two of them living in my house. Except they think it's their house and they let me live in it. If you like cats, think of a rat, or a dog, or any creature you don't like. Doesn't affect the argument.

 

[eanassir]

Dexter Sinister, it's a matter of imagination; it's only a relative thing.
The last thing I say:
It is different from the Earth rotation around itself. The Earth rotates around itself and around the Sun; now suppose the Earth does not rotate around the Sun, will it go on spinning around itself? Yes.
And suppose the Moon does not rotate around the Earth, will it spin round itself? No.

 

[IdRatherBeSkiing]

And suppose the Moon does not rotate around the Earth, will it spin round itself? No.

Yes.

 

[Dexter Sinister]

Dexter Sinister, it's a matter of imagination; it's only a relative thing.

No it's not, it's a simple matter of empirical fact.

It is different from the Earth rotation around itself.

No it's not, it's exactly the same, except for the periodicity: Earth, 24 hours; moon, 28 days. Approximately.

The Earth rotates around itself and around the Sun; now suppose the Earth does not rotate around the Sun, will it go on spinning around itself? Yes.

Yes. If the sun suddenly disappeared, the earth would take off on a line tangent to its orbit about 8 minutes later, and it would still be spinning on its axis once in about 24 hours.

And suppose the Moon does not rotate around the Earth, will it spin round itself? No.

Yes. If the earth suddenly disappeared, the moon would take off on a line tangent to its orbit a little over a second later, and it would still be turning on its axis once in about 28 days. That's the point you're not getting.

 

[s_lone]

Yes. If the sun suddenly disappeared, the earth would take off on a line tangent to its orbit about 8 minutes later, and it would still be spinning on its axis once in about 24 hours.
Yes. If the earth suddenly disappeared, the moon would take off on a line tangent to its orbit a little over a second later, and it would still be turning on its axis once in about 28 days. That's the point you're not getting.

This may sound picky Dex, but are you saying gravity 'travels' at the speed of light?

You're saying that if the sun suddenly disappeared, the earth would take off on a line tangent to its orbit about 8 minutes later (the time it takes for light to travel from the sun to the earth)...

But are you convinced of that? If gravity is a curvature of spacetime, wouldn't the effect on the earth's trajectory be instantaneous if the sun suddenly disappeared (even if it would have no reason to so!)

...

...edited after a bit of thought and research...

forget about what I just asked... I did my research and realize Einstein's theory of relativity implies that the effects of gravity do travel at the speed of light... But I'm happy I asked the question because it helped me understand the theory better... I'm very slowly but surely learning to understand what physicians are talking about...

 

[Just the Facts]

The example of the two balls, that you mentioned, can be used to explain the subject: Suppose that two balls of wood one resembling the Moon, and the other resembles the Earth, these two balls being fixed by a ruler with nails so that the Moon ball cannot rotate around itself, the axis of rotation is in the centre of the Earth ball, so when the Earth ball rotates around its axis, it drags the ruler and the Moon ball with it to rotate around the Earth ball; the Moon ball will not rotate around its axis.
Now, if there is a light globe in front of the two balls, then all the surface of the Moon ball will get the light gradually as it goes in its rotation around the Earth ball; so the Moon ball will appear as if it has rotated around itself in relation to the light globe, while in fact it does not rotate around itself because it is fixed by nails to the wood ruler and cannot rotate.
Moreover, the point selected let it be the point where the ruler is fixed to the Moon ball; this point will go round about the Earth ball, while the Moon ball does not rotate around its axis because it is fixed with nails to the ruler.
With best regards.
eanassir​

http://universeandquran.741.comhttp://universeandquran.741.com

I don't understand the point of this example. Maybe I'm misunderstanding, but it seems to me such a model would make the moon visible only from one side of the Earth. I'm sure it's been quite well documented that that's not the case.

Also, in doing some research, there seems to be pretty good seismic evidence that the moon does indeed have a crust and a core, and is not a solid ball of rock.

 

[Dexter Sinister]

...tell us why the Earth rotate around its axis. In other words: we know that Earth rotates around its axis, but what makes it rotate around itself ? Consult your friends, the atheists, would they answer such a simple question?

Is the earth rotating around itself different from rotating around its axis in your view? That's what your question suggests, but they're the same thing. Conservation of the angular momentum in the original cloud of gas and dust and whatnot that the solar system was formed from is the reason why everything in the solar system rotates in various ways. Had there been no angular momentum in the original cloud, the solar system could not have formed at all. It's elementary first year physics. Pierre-Simon, Marquis de Laplace, figured out the basics of it about 200 years ago.

And by the way, I'm not an astronomer, and most of my friends aren't atheists.

 

[lone wolf]

If Pluto is a dog, what is Goofy?

Wolf

 

[#juan]

If Pluto is a dog, what is Goofy?

Wolf

Thinking Pluto orbits Neptune...........for one thing..

 

[lone wolf]

Gotta love it when a lead makes contact!

Wolf

 

[#juan]

Gotta love it when a lead makes contact!

Wolf

You did throw that one belt high, right over the plate....thanks...:lol:

 

[karrie]

oh, you guys are so clever. LOL.

 

[Dexter Sinister]

I don't understand the point of this example.

Don't worry about it, neither does eanassir, and his conclusion from it is false anyway. He doesn't understand frames of reference, or in common parlance, points of view, or vectors, or forces, or much else about the subjects called kinematics and dynamics. He doesn't see that the fact that the moon's orbital period equals its rotational period doesn't mean it isn't rotating. He's stuck in an earthbound perspective, gets his scientific information from pre-scientific religious texts, or from people who base their thinking on them, and can't think outside that box. All you have to do is hold a stick by one end, throw it, and watch how it behaves (it'll rotate in flight, but from the perspective of the thrower it doesn't apparently begin to rotate until you let go of it) to see how wrong he is, but he's either never done that or not been able to generalize from what he saw.

 

[Niflmir]

This may sound picky Dex, but are you saying gravity 'travels' at the speed of light?

You're saying that if the sun suddenly disappeared, the earth would take off on a line tangent to its orbit about 8 minutes later (the time it takes for light to travel from the sun to the earth)...

But are you convinced of that? If gravity is a curvature of spacetime, wouldn't the effect on the earth's trajectory be instantaneous if the sun suddenly disappeared (even if it would have no reason to so!)

...

...edited after a bit of thought and research...

forget about what I just asked... I did my research and realize Einstein's theory of relativity implies that the effects of gravity do travel at the speed of light... But I'm happy I asked the question because it helped me understand the theory better... I'm very slowly but surely learning to understand what physicians are talking about...

Actually, if you applied a Heaviside function to the stress energy tensor the information need not propagate out at the speed of light. Due to the Rankine-Hugoniot condition the schock wave could propagate out faster than the speed of information transmission. I am not sure if anyone has analysed this mostly due to the incredible unphysicality of the sun vanishing without trace. (And the infinite energy at the junction of existence/nonexistence)

If you want a similar example in a "simpler" physical theory, consider the Navier-Stokes equations. Consider an atomic bomb explosion. The shock wave from the explosion propagates through the air at a velocity greater than the speed of sound; so before you even hear a rumbling there is a flash and your flash is flayed from your skeleton.

 

[eh1eh]

Lots of ink about a grade school physics lesson. :-?

BTW, the sky is not blue.

 

[Dexter Sinister]

Actually, if you applied a Heaviside function to the stress energy tensor ...

Well, we're dealing with first approximations here, where the influence of gravity spreads at the speed of light. You're getting a little advanced for anything but a crowd of physics graduate students. There aren't many of them here, and for sure eanassir isn't one of them. I'm also a little doubtful that classical compressible fluid flow equations would apply in this case, but you know far more about this stuff than I do.

 

[Niflmir]

Well, we're dealing with first approximations here, where the influence of gravity spreads at the speed of light. You're getting a little advanced for anything but a crowd of physics graduate students. There aren't many of them here, and for sure eanassir isn't one of them. I'm also a little doubtful that classical compressible fluid flow equations would apply in this case, but you know far more about this stuff than I do.

Yeah, I know. One always hopes that people are interested in their work of course. That sort of problem is something I always liked talking about with my colleagues. Definitely pure speculation, back to the contradiction.

 

[Dexter Sinister]

...back to the contradiction.

No it isn't... :lol:

 

[eh1eh]

No it isn't... :lol:

You're right, it's not.