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Posted 3 Weeks Ago by  The_Jon_m - Young, Educated and proud to be so. Bluesman of the Parish - Forgot about Dre
I don't think there is a one-size-fits-all responce for non eg stuff
and yes, I admitt, I get grumpy at some people (ie the guy who posted some rubbish then said it was in the spirt of the hitchhiker's guide)
but there are people who post something fun / interesting that is no way EG - like a poem or something -
this needs a differnet repsonce for rubbish non-science and personal theories, where we are not just dealing with somebody who has skipped over the rules, but has their own odd belives about how the world works.
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Posted 3 Weeks Ago by FordsTowel
Sorry Gnomon, that I posted that note in relation to the wrong thread, but you are wrong. PR is precisely about asking the opinions of the other researchers.
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Posted 3 Weeks Ago by Gnomon
Yes, you're right.
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Posted 3 Weeks Ago by FordsTowel
NP, my friend.
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Posted 2 Weeks Ago by matterdoc
I thank all those who welcomed my entry into h2g2. I also appreciate all those who spared their time and effort to comment on my article. However, I wish the criticisms were more on scientific matter rather than on my personal traits.
Kepler’s first law of planetary motion states that ‘The orbit of every planet is an ellipse with sun at a focus’ (Wikipedia). Ellipse is a closed geometrical figure. The law does not say anything about the shape of a satellite’s orbital path. Probably, satellites were not considered during formulation of these laws. Or else, knowing that he moon is orbiting about the moving earth, they were intentionally excluded. Kepler’s laws of planetary motion were formulated to account for the motion of planets around the (assumed) static sun. We must consider that, when ‘Kepler’ formed his ‘laws on planetary motions’ even the heliocentric nature of the solar system was not recognized, let alone a moving sun. All cosmic bodies were considered to orbit around a static earth.
Kepler’s laws on planetary motions are valid only on condition that his first law is true, which requires the planet to orbit around its central body in elliptical (closed geometrical) path. The moment astronomers realized that the sun (central body) is a moving object, Kepler’s laws became invalid. Because, no free body can orbit around another moving body in a closed geometrical path. Now, since we now know that the sun is a moving body, we should acknowledge the true shape of a planetary orbital path as ‘wavy about a central body’ instead of ‘circular/elliptical around a central body’.
I will be grateful if ‘Gnomon’ could give me references to few articles/books in popular literature, text books, atlases, theory books, thesis or internet sites which show the shape of planetary orbits as wavy about their central bodies. It is obvious that my search for them was faulty and I missed such widely known information. Astronomers may privately agree to the suggestion of wavy orbital paths, but they do not wish to make such public comment. May be I am wrong in suggesting that what ‘every astronomer knows as a fact’ is not publicized in any form. If a person shakes his head long enough, the whole universe may appear to be shaking to him. ‘Gnomon’ would say the most logical way for him, to treat such appearance, is by formulating a law on shaky universe and continuously defend that law by equally imaginative theories.
Straight-line motion of a golf ball on a moving ship’s deck is apparent and within the small reference frame of the ship. Due to their mechanical linkage, the golf ball has certain parameters of ship’s motion already embedded in it. It is its relative motion with respect to the ship that appears to be in straight line. Its real motion is much more complex. Only real motions can be used in an absolute reference frame. However, for mathematical treatments in smaller reference frames, we get accurate results by using relative motions. This is because we ignore parameters of real motions, both in the input functions and in the result. This is the practical and simpler method. This does not make it the most logical method.
Since there is no mechanical link between a planetary body and its central body, parameters of their motions cannot be transferred to each other. Their real motions (other than for gravitational effects) remain independent of each other and are related only in absolute reference frame. For practical purposes, we use representations of these motions (in relation to each other) in mathematics to predict events (in most cases) accurately. To insist such representations (apparent orbital paths) are true motions is to bend the truth a bit.
In mathematics, we often split actions/entities into components to make the treatments simpler. To find the center of gravity of an odd-shaped object, we may consider it as a combination of many regular shaped bodies. This does not mean that there are as many bodies present. All representations used in mathematics are symbolic and they may not always correspond to reality.
In mathematics, centers of mass and gravity are imaginary points to represent wider area of actions, to make explanations simpler. There are created in our minds and are needed to simplify mathematical treatments. Real actions do not take place on or about these points. Take the case of an odd-shaped body, whose center of gravity falls outside the body. You can neither apply a force on the body through this point nor does the body have any direct link to the point. Hence, it is not that a body moves about its center of mass but the center of mass is created by us to understand the motion.
Mathematics is often a very good tool to understand the nature but it is not right to insist that the nature should always work according to the mathematics.
matterdoc
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Posted 2 Weeks Ago by Gnomon
Hi Matterdoc. Try looking up Newton's "Principle of Relativity", which explains why you don't have to go to the trouble of considering the wavy lines.
But whether you consider them or not, you will still get the same answers, except that the wavy lines method is much, much harder to work out.
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Posted 2 Weeks Ago by Gnomon
I think the problem here is this:
"This is the practical and simpler method. This does not make it the most logical method."
You think it does not make it the most logical method. All the rest of the world thinks it does.
Everyone knows the Earth orbits around the Sun and it's certainly no secret that the Sun orbits around the centre of the Galaxy. See Wikipedia "Earth's Orbit". The Galaxy itself is moving with respect to other nearby galaxies, although it doesn't appear to be orbiting around anything as far as we know. The Earth orbits around the Sun in an elliptical orbit with respect to the Sun. The Sun orbits around the centre of the galaxy in an elliptical orbit with respect to the galaxy.
In the frame of reference of the Sun, the Earth's orbit is an ellipse. In the frame of reference of the Galaxy, it is not. But it is ridiculous to say that the frame of reference of the galaxy is the true one, because Einstein showed that any frame of reference is equally valid. So you pick the one which gives the simplest results. For observing the stars, it is often simplest to pick the frame of reference where the Earth is the centre and the Sun orbits around it. This makes many of the calculations a lot easier.
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Posted 2 Weeks Ago by The_Jon_m - Young, Educated and proud to be so. Bluesman of the Parish - Forgot about Dre
I personally don't think that an entry on orbits that doesn't mention Einstein is not worth letting into the edited guide.
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