| Topic: |
Science > Physics |
| User: |
"Michael Moroney" |
| Date: |
10 Sep 2006 02:05:36 PM |
| Object: |
Disproof of Ptolemaic system? |
Is there a way to absolutely disprove the following claim?
"Whether the earth orbits the sun or the sun moves around the earth
depends only on your choice of your reference. The physics is just much
simpler if you choose the heliocentric model." The comparison is supposed
to be the same as that of whether A is stationary and B is moving, or B is
stationary and A is moving depends on on your choice of reference frame.
I mean an absolute proof, not just something that's possible but absurd
disproving it by the absurdity (such as parallax of near stars could be
caused by the stars moving in small elipses, or the change in the visible
constellations being caused by the stars moving as if on a sphere like
the ancients once believed)
.
|
|
| User: "George Dishman" |
|
| Title: Re: Disproof of Ptolemaic system? |
10 Sep 2006 04:16:32 PM |
|
|
"Michael Moroney" <moroney@world.std.spaamtrap.com> wrote in message
news:ee1nm0$rc5$1@pcls4.std.com...
Is there a way to absolutely disprove the following claim?
"Whether the earth orbits the sun or the sun moves around the earth
depends only on your choice of your reference. The physics is just much
simpler if you choose the heliocentric model." The comparison is supposed
to be the same as that of whether A is stationary and B is moving, or B is
stationary and A is moving depends on on your choice of reference frame.
No, the claim is correct. I believe general relativity
can handle arbitrary frames.
I mean an absolute proof, not just something that's possible but absurd
disproving it by the absurdity (such as parallax of near stars could be
caused by the stars moving in small elipses, ...
Such motion would violate conservation of momentum so
that is about as good a proof as you will get.
George
.
|
|
|
|
| User: "Michael Moroney" |
|
| Title: Re: Disproof of Ptolemaic system? |
10 Sep 2006 05:22:12 PM |
|
|
I think I should word my question another way. Imagine a stellar system
with a star and only one planet, with no asteroids, comets, moons or
anything else, and this stellar system is completely surrounded by a
dark nebula so no other stars are visible. An intelligent civilization
evolves there. This civilization should be able to answer the question
whether their sun goes around their planet once a day or their planet
rotates, by observing coriolis effects on storms. Can they tell whether
their planet goes around their sun, or their sun goes around their planet
once during one of their years?
(Oh yes, I know both travel around their common center of gravity)
.
|
|
|
| User: "George Dishman" |
|
| Title: Re: Disproof of Ptolemaic system? |
11 Sep 2006 02:59:45 PM |
|
|
"Michael Moroney" <moroney@world.std.spaamtrap.com> wrote in message
news:ee236k$3hd$1@pcls4.std.com...
I think I should word my question another way. Imagine a stellar system
with a star and only one planet, with no asteroids, comets, moons or
anything else, and this stellar system is completely surrounded by a
dark nebula so no other stars are visible. An intelligent civilization
evolves there. This civilization should be able to answer the question
whether their sun goes around their planet once a day or their planet
rotates, by observing coriolis effects on storms. Can they tell whether
their planet goes around their sun, or their sun goes around their planet
once during one of their years?
(Oh yes, I know both travel around their common center of gravity)
In theory a gyroscope (or the Sagnac effect)
will tell them there is relative motion.
In theory they can derive Newtonian mechanics
and the inverse square law of gravity (by tests
of weights in the lab) from which the two-body
problem can be solved by maths. That would tell
them the bodies both move round the barycentre.
George
.
|
|
|
|
| User: "Sorcerer" |
|
| Title: Re: Disproof of Ptolemaic system? |
10 Sep 2006 06:27:04 PM |
|
|
"Michael Moroney" <moroney@world.std.spaamtrap.com> wrote in message
news:ee236k$3hd$1@pcls4.std.com...
|I think I should word my question another way. Imagine a stellar system
| with a star and only one planet, with no asteroids, comets, moons or
| anything else, and this stellar system is completely surrounded by a
| dark nebula so no other stars are visible. An intelligent civilization
| evolves there. This civilization should be able to answer the question
| whether their sun goes around their planet once a day or their planet
| rotates, by observing coriolis effects on storms. Can they tell whether
| their planet goes around their sun, or their sun goes around their planet
| once during one of their years?
|
| (Oh yes, I know both travel around their common center of gravity)
Ask a dolphin. They just about meet your requirements.
Androcles
.
|
|
|
|
| User: "Sam Wormley" |
|
| Title: Re: Disproof of Ptolemaic system? |
10 Sep 2006 06:00:45 PM |
|
|
Michael Moroney wrote:
I think I should word my question another way. Imagine a stellar system
with a star and only one planet, with no asteroids, comets, moons or
anything else, and this stellar system is completely surrounded by a
dark nebula so no other stars are visible. An intelligent civilization
evolves there. This civilization should be able to answer the question
whether their sun goes around their planet once a day or their planet
rotates, by observing coriolis effects on storms. Can they tell whether
their planet goes around their sun, or their sun goes around their planet
once during one of their years?
(Oh yes, I know both travel around their common center of gravity)
Orbital Velocity (Speed) = sqrt(GM/r)
where M is the mass of the body being orbited and r is the radius of
the orbit. Try it for each body.
Applying Newton's laws of motion and gravitation, the true
situation emerges.
Celestial Mechanics
http://scienceworld.wolfram.com/physics/topics/CelestialMechanics.html
.
|
|
|
| User: "Jeff Root" |
|
| Title: Re: Disproof of Ptolemaic system? |
10 Sep 2006 11:59:11 PM |
|
|
Sam Wormley wrote:
Orbital Velocity (Speed) = sqrt(GM/r)
where M is the mass of the body being orbited and r is
the radius of the orbit. Try it for each body.
Applying Newton's laws of motion and gravitation, the
true situation emerges.
Newton had reasonably good estimates of the Earth's mass,
the Moon's distance from the Earth, and the orbital period
of the Moon from which to work out the law of gravitation.
When only a planet and a Sun are available, with no stars
in the background for reference, you can't get the needed
measurements to calculate anything. Even if did calculate
something you wouldn't have anything to measure to test
your equations to determine whether they are right.
-- Jeff, in Minneapolis
.
|
|
|
| User: "Sam Wormley" |
|
| Title: Re: Disproof of Ptolemaic system? |
11 Sep 2006 08:31:58 AM |
|
|
Jeff Root wrote:
Sam Wormley wrote:
Orbital Velocity (Speed) = sqrt(GM/r)
where M is the mass of the body being orbited and r is
the radius of the orbit. Try it for each body.
Applying Newton's laws of motion and gravitation, the
true situation emerges.
Newton had reasonably good estimates of the Earth's mass,
the Moon's distance from the Earth, and the orbital period
of the Moon from which to work out the law of gravitation.
When only a planet and a Sun are available, with no stars
in the background for reference, you can't get the needed
measurements to calculate anything. Even if did calculate
something you wouldn't have anything to measure to test
your equations to determine whether they are right.
-- Jeff, in Minneapolis
The earth is rotating.
Coriolis Force
http://scienceworld.wolfram.com/physics/CoriolisForce.html
Foucault Pendulum
http://scienceworld.wolfram.com/physics/FoucaultPendulum.html
Additional Information
o distance (radar ranging)
o solar flux
o solar output
o pp chain neutrinos
o solar structure (density, temperature, mass)
o etc.
.
|
|
|
| User: "Sam Wormley" |
|
| Title: Re: Disproof of Ptolemaic system? |
11 Sep 2006 08:34:47 AM |
|
|
Sam Wormley wrote:
Jeff Root wrote:
Sam Wormley wrote:
Orbital Velocity (Speed) = sqrt(GM/r)
where M is the mass of the body being orbited and r is
the radius of the orbit. Try it for each body.
Applying Newton's laws of motion and gravitation, the
true situation emerges.
Newton had reasonably good estimates of the Earth's mass,
the Moon's distance from the Earth, and the orbital period
of the Moon from which to work out the law of gravitation.
When only a planet and a Sun are available, with no stars
in the background for reference, you can't get the needed
measurements to calculate anything. Even if did calculate
something you wouldn't have anything to measure to test
your equations to determine whether they are right.
-- Jeff, in Minneapolis
The earth is rotating.
Coriolis Force
http://scienceworld.wolfram.com/physics/CoriolisForce.html
Foucault Pendulum
http://scienceworld.wolfram.com/physics/FoucaultPendulum.html
Additional Information
o distance (radar ranging)
o solar flux
o solar output
o pp chain neutrinos
o solar structure (density, temperature, mass)
o etc.
We can even deduce orbital period of the earth via
o tilt of the sun's axis of rotation
o annual variation in the earth sun distance
.
|
|
|
|
|
|
|
| User: "Jeff Root" |
|
| Title: Re: Disproof of Ptolemaic system? |
10 Sep 2006 05:47:21 PM |
|
|
Michael,
Your second attempt does a very good job of setting up
the scenario. I can't answer the question, but it looks to
me that it will be very difficult or impossible for people on
the planet to measure the distance to their Sun, and thus
have any idea of its size and mass compared to their
planet. So they will likely never realize how large it is,
and assume the simplest explanation, that it goes around
their planet.
Also, with only the one star to serve as a reference, they
may never realize that the Sun follows an odd path through
the sky because their planet rotates AND orbits the Sun,
and the axis of their plant's rotation is not perpendicular
to the plane of the orbit. Of course, a Foucault pendulum
would show the rotation, but that wouldn't necessarily be
convincing proof.
Without any destination to go after, it seems unlikely that
space exploration would develop to the point that they could
circumnavigate the Sun, although an un"manned" probe
around the Sun would be able to determine the Sun's size
and distance by radio travel times.
-- Jeff, in Minneapolis
.
|
|
|
|
|
| User: "Steve Willner" |
|
| Title: Re: Disproof of Ptolemaic system? |
12 Sep 2006 02:13:04 PM |
|
|
In article <ee1nm0$rc5$1@pcls4.std.com>,
(Michael Moroney) writes:
Is there a way to absolutely disprove the following claim?
"Whether the earth orbits the sun or the sun moves around the earth
depends only on your choice of your reference. The physics is just much
simpler if you choose the heliocentric model."
Annual variation of radial velocity?
In general, though, if you are willing to make your physical laws
sufficiently complicated, you can probably explain any one observed
phenomenon in a variety of ways. (As for parallax: as you say, maybe
all the stars orbit unseen companions with periods of one year. That
explanation would most likely break down, though, if we could observe
from Mars.) The quest in science is for physical laws that are as
simple as possible while explaining the widest possible variety of
observations without contradictions.
--
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA
(Please email your reply if you want to be sure I see it; include a
valid Reply-To address to receive an acknowledgement. Commercial
email may be sent to your ISP.)
.
|
|
|
| User: "Sorcerer" |
|
| Title: Re: Disproof of Ptolemaic system? |
12 Sep 2006 04:34:13 PM |
|
|
"Steve Willner" <willner@cfa.harvard.edu> wrote in message
news:450706c0$1@cfanews.cfa.harvard.edu...
| In article <ee1nm0$rc5$1@pcls4.std.com>,
| (Michael Moroney) writes:
| > Is there a way to absolutely disprove the following claim?
| > "Whether the earth orbits the sun or the sun moves around the earth
| > depends only on your choice of your reference. The physics is just much
| > simpler if you choose the heliocentric model."
|
| Annual variation of radial velocity?
That will not do it. The man asked for proof.
The physics is just much harder if you choose the geocentric model.
| In general, though, if you are willing to make your physical laws
| sufficiently complicated, you can probably explain any one observed
| phenomenon in a variety of ways. (As for parallax: as you say, maybe
| all the stars orbit unseen companions with periods of one year. That
| explanation would most likely break down, though, if we could observe
| from Mars.) The quest in science is for physical laws that are as
| simple as possible while explaining the widest possible variety of
| observations without contradictions.
I agree with your point of view.
That is why I've produced these pages.
http://www.androcles01.pwp.blueyonder.co.uk/Rocket/Rocket.htm
http://www.androcles01.pwp.blueyonder.co.uk/Algol/Algol.htm
Androcles.
.
|
|
|
|
| User: "Paul Schlyter" |
|
| Title: Re: Disproof of Ptolemaic system? |
12 Sep 2006 03:15:43 PM |
|
|
In article <450706c0$1@cfanews.cfa.harvard.edu>,
Steve Willner <willner@cfa.harvard.edu> wrote:
In article <ee1nm0$rc5$1@pcls4.std.com>,
moroney@world.std.spaamtrap.com (Michael Moroney) writes:
Is there a way to absolutely disprove the following claim?
"Whether the earth orbits the sun or the sun moves around the earth
depends only on your choice of your reference. The physics is just much
simpler if you choose the heliocentric model."
Annual variation of radial velocity?
In general, though, if you are willing to make your physical laws
sufficiently complicated, you can probably explain any one observed
phenomenon in a variety of ways. (As for parallax: as you say, maybe
all the stars orbit unseen companions with periods of one year. That
explanation would most likely break down, though, if we could observe
from Mars.) The quest in science is for physical laws that are as
simple as possible while explaining the widest possible variety of
observations without contradictions.
One could even try a modern variety of the Tychonian system: the Sun,
with all its planets (except the Earth) as well as the rest of the
universe, orbits the Earth...... the "true believers" will always
be able to fabricate an "explanation"..... :-)
--
----------------------------------------------------------------
Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
e-mail: pausch at stockholm dot bostream dot se
WWW: http://stjarnhimlen.se/
.
|
|
|
|
|
| User: "Sam Wormley" |
|
| Title: Re: Disproof of Ptolemaic system? |
10 Sep 2006 03:24:56 PM |
|
|
Michael Moroney wrote:
"Whether the earth orbits the sun or the sun moves around the earth
depends only on your choice of your reference.
They orbit their common center of gravity. Period!
.
|
|
|
|
| User: "John Curtis" |
|
| Title: Re: Disproof of Ptolemaic system? |
11 Sep 2006 10:21:52 AM |
|
|
Michael Moroney wrote:
Is there a way to absolutely disprove the following claim?
"Whether the earth orbits the sun or the sun moves around the earth
depends only on your choice of your reference. The physics is just much
simpler if you choose the heliocentric model." The comparison is supposed
to be the same as that of whether A is stationary and B is moving, or B is
stationary and A is moving depends on on your choice of reference frame.
I choose the Galactocentric frame where neither the Earth nor the Sun
are stationary, but are moving toward the Galactic Center. Because
the Earth maintains the same orientation throughout the journey (leans
toward Polaris), it does not fly around the Sun as illustrated by the
behaviour of XMM-Newton:
http://www.sr.bham.ac.uk/xmm/moments3.html
The illusion of Earth circling around the Sun is produced by
Earth and Sun alternating in passing each other on their way toward
the Galactic Center.
When in front of the Sun, Earth is slowed by Sun's gravity, thus
allowing the Sun to pass the Earth.
When behind the Sun, Earth is accelerated by Sun's gravity (plus
the pull of Galactic Center) to pass the Sun.
A corollary is that the Sun and the planets move with the same
galactic speed, which matches the galactic rotation curves.
John Curtis
.
|
|
|
|
| User: "Eric Chomko" |
|
| Title: Re: Disproof of Ptolemaic system? |
12 Sep 2006 03:23:17 PM |
|
|
Michael Moroney wrote:
Is there a way to absolutely disprove the following claim?
"Whether the earth orbits the sun or the sun moves around the earth
depends only on your choice of your reference. The physics is just much
simpler if you choose the heliocentric model." The comparison is supposed
to be the same as that of whether A is stationary and B is moving, or B is
stationary and A is moving depends on on your choice of reference frame.
I mean an absolute proof, not just something that's possible but absurd
disproving it by the absurdity (such as parallax of near stars could be
caused by the stars moving in small elipses, or the change in the visible
constellations being caused by the stars moving as if on a sphere like
the ancients once believed)
Look up Tychonic system: http://en.wikipedia.org/wiki/Tychonic_system
and it will show that there is no difference geometrically between
Tycho's model and that of Copernicus. The former states that sun orbits
the earth and the other planets orbit the sun. Which is different than
Ptolemy where everything orbits the earth.
Eric
.
|
|
|
| User: "Paul Schlyter" |
|
| Title: Re: Disproof of Ptolemaic system? |
13 Sep 2006 03:13:10 AM |
|
|
In article <1158092597.119275.65010@p79g2000cwp.googlegroups.com>,
Eric Chomko <pne.chomko@verizon.net> wrote:
Michael Moroney wrote:
Is there a way to absolutely disprove the following claim?
"Whether the earth orbits the sun or the sun moves around the earth
depends only on your choice of your reference. The physics is just much
simpler if you choose the heliocentric model." The comparison is supposed
to be the same as that of whether A is stationary and B is moving, or B is
stationary and A is moving depends on on your choice of reference frame.
I mean an absolute proof, not just something that's possible but absurd
disproving it by the absurdity (such as parallax of near stars could be
caused by the stars moving in small elipses, or the change in the visible
constellations being caused by the stars moving as if on a sphere like
the ancients once believed)
Look up Tychonic system: http://en.wikipedia.org/wiki/Tychonic_system
and it will show that there is no difference geometrically between
Tycho's model and that of Copernicus. The former states that sun orbits
the earth and the other planets orbit the sun. Which is different than
Ptolemy where everything orbits the earth.
Eric
Geometrically there is one difference: in the Tychonian system, stars
would show neither aberration nor parallax - in the Copernican system
it would show both. And that's probably why Tycho invented his
system: he had made the (so far) most accurate measurements of stellar
positions and was still unable to detect any parallax (neither
aberration nor finite light speed had even been considered yet). This
must have made Tycho conclude that the Earth must be stationary - and
so he invented the Tychonian system. Yes, it is physically
impossible, but Newton's physics was then still in the future. And
the Tychonian system did "save the phenomena", as far as Tycho was
concerned: it explained the "absence" of stellar parallax as well as
why the retrogade motions of the planets always occurs around when the
planet is in opposition (or, for Mercury and Venus, in inferior
conjunction).
The Tychonic system is also an example of what might happen when you
construct an ad hoc theory just for the purpose of making it fit
the observations, without understanding the actual mechanisms at work.
--
----------------------------------------------------------------
Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
e-mail: pausch at stockholm dot bostream dot se
WWW: http://stjarnhimlen.se/
.
|
|
|
|
|
|
Related Articles |
|
|
