Re: About Galileo and the Galilean relativity

On Apr 2, 8:10 am, "Shaktyai" <Fabrice.All...@xxxxxxxxx> wrote:
On Apr 1, 8:49 pm, "oriel36" <kelleher.ger...@xxxxxxxxx> wrote:





On Apr 1, 2:29 pm, "Shaktyai" <Fabrice.All...@xxxxxxxxx> wrote:

I am always amazed by the difference between what popular medias know
of the Galilean relativity, what my students understand of it and
what Galileo is supposed to have written. Here is a good way of
drinking free beer:

Ask ten people to select the proper statement:

1) Is the sun and all the planets revolving around the earth ?
2) Is the earth and all the planets revolving around the sun ?

I have already lost two years in a row a bet with a friend by pooling
my students. I had bet they would have answered: none of the two
statement is true.

So my question comes to this:
Does any one know if Galileo did really say and write that the
heliocentric referential is an absolute preffered referential, or is
it just what the non astronomers have understood of Galileo's
writting ?
And does anyone know if what is todays known as the Galilean
relativity was ever written and thought by Galileo ?

In order to support my scientific thirst I ask you to send me the
equivalent of 25% (in money) of the free beers you will drink because
of me.

Salute forza el canute

Galileo's statements are in line with Copernicus and with Kepler's in
the matter of heliocentric reasoning which uses the Earth's orbital
motion to explain the observed behavior of our planet along with the
others around the central Sun -

"[Here Salviati explains Jupiter's motion, then follows with:]

Now what is said here of Jupiter is to be understood of Saturn and
Mars also. In Saturn these retrogressions are somewhat more frequent
than in Jupiter, because its motion is slower than Jupiter's, so that
the Earth overtakes it in a shorter time. In Mars they are rarer, its
motion being faster than that of Jupiter, so that the Earth spends
more time in catching up with it. Next, as to Venus and Mercury, whose
circles are included within that of the Earth, stoppings and
retrograde motions appear in them also, due not to any motion that
really exists in them, but to the annual motion of the Earth. This is
acutely demonstrated by Copernicus . . .

You see, gentlemen, with what ease and simplicity the annual motion --
if made by the Earth -- lends itself to supplying reasons for the
apparent anomalies which are observed in the movements of the five
planets. . . . It removes them all and reduces these movements to
equable and regular motions; and it was Nicholas Copernicus who first
clarified for us the reasons for this marvelous effect." 1632,
Dialogue Concerning the Two Chief World Systems

It was Newton who jumped the tracks in approaching and trying to
resolve retrogrades.It is like an act of vandalism when it is honestly
compared with what Galileo wrote and affirming the earlier work of
Copernicus and Kepler -

" For to the earth planetary motions appear sometimes direct,
sometimes stationary, nay, and sometimes retrograde. But from the sun
they are always seen direct," Newton

I have only post a dozen times or so in this forum over the last year
and I am winding down altogether.There is always enough time to
address an honest question like yours but in truth,if you come across
the time lapse footage of the Earth overtaking Jupiter and Saturn,all
questions will be answered -

http://antwrp.gsfc.nasa.gov/apod/image/0112/JuSa2000_tezel.gif

Thank you for your time and your intelligent and kind way of answering
my questions. It is pretty rare nowdays with ultra egotic would-like-
to-be physicists.>From what I have understood of Galileo's transcript it appears that in

Galileo's mind the motion of the planets around the sun was an
absolute truth. He did not seem to have realized at this stage that
the difference between his positions and the Church's ones were
merelly du to a change of referential.

Most of what you read today of the Church's opposition to
heliocentricity is really a local political maneuver by the then Pope
to put Galileo in his place rather than an underlying opposition.The
original text of Copernicus and especially in his letter to the Pope
Paul III shows that reasonable men would have at least a working
knowledge and understanding of the basics behind the great insight
which uses orbital motion to explain the observed behavior of the
planets and axial rotation to explain the daily cycle -

http://webexhibits.org/calendars/year-text-Copernicus.html






He was advocating for the sun
to be the center of the universe while the later was for the earth.
That may explain why even todays so many people beleive and say that
the earth and all the planets are orbiting the sun in an elliptic way
without even mentioning the referential.

The working language of astronomers is taking into account the axial
and orbital motions of the Earth whereas the Ptolemaic astronomers
reasoned from a stationary Earth.The language of Galileo and Kepler,in
affirming the Copernican insight,is always focused on the orbitally
moving Earth to resolve apparent planetary motions and I add Kepler's
statement to that of Galileo in support of this -

"Copernicus, by attributing a single annual motion to the earth,
entirely rids the planets of these extremely intricate coils [spiris],
leading the individual planets into their respective orbits
[orbitas],quite bare and very nearly circular. In the period of time
shown in the diagram, Mars traverses one and the same orbit as many
times as the 'garlands' [corollas] you see looped towards the
centre,with one extra, making nine times, while at the same time the
Earth repeats its circle sixteen times " Astronomia Nova 1609 KEPLER

As you are not familiar with the Panis Quadragesimalis of Kepler (the
'garlands' he refers to in the above excerpt) it is unlikely that you
will recognise where Newton jumped the tracks.All I can do is show you
the actual time lapse footage of the slower moving outer planets and
hope you recognise that we doo see orbital motion around the Sun
directly fromn an orbitally moving Earth -

http://antwrp.gsfc.nasa.gov/apod/image/0112/JuSa2000_tezel.gif

You can see how the faster orbitally moving Earth gets rid of the
spirals just as Kepler recognises,even without the benefit of
contemporary imaging,you can also see where the whole thing becomes
derailed at Newton -

" For to the earth planetary motions appear sometimes direct,
sometimes stationary, nay, and sometimes retrograde. But from the sun
they are always seen direct," Newton





Before Galileo the human kind used to beleive earth was the center of
the universe, after Galileo they beleive it is the sun.- Hide quoted text -

- Show quoted text -

Before Copernicus,astronomers believed that the Sun's position was
beteween Venus and Mars.By allowing that the Earth's orbital motion
between Venus and Mars resolved the observed behavior of the other
planets and axial rotation took care of the daily cycle,a revolution
took place long before Galileo.Sadly, the great astronomical advances
withered in the late 17th century atmosphere with the rise of
empiricism and so it remains to this day.




.

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