Relative postion and speed of light

Because of the speed of light, we see the sun, the planets, the stars, and
the person we are kissing after the fact. The sun is what, 2 degrees beyond
the point in the sky that we see it? Saturn something like 20 degrees at
this time of year? The other planets and stars all at different phases.
And this is constantly changing because of orbital movement, etc. We have
circled the sun 4 times before light from Alpha Centauri hits us. God knows
where it actually is when it does hit us.

If gravity is Newtonian, then there is quite a sizeable angular relationship
between the gravitational relationship of a point on one object, and the
time that light was emitted from another object striking it. If gravity
moves at the speed of light there is still a sizeable difference. Even more
so when you figure the time differential of the light coming off an object
being retransmitted, such as from the planets. Meaning the energy transfer
time and composition of the surface versus light directly transmitted from a
star.

So much for the supposed accuracy of astrology.

So, how do scientists take into account this myriad of movement and force
relationships on the macro and micro scales?

Dear Dave Nelson:

"Dave Nelson" wrote in message
ink.net...
Because of the speed of light, we see the sun, the planets, the stars,
and
the person we are kissing after the fact. The sun is what, 2 degrees
beyond
the point in the sky that we see it? Saturn something like 20 degrees at
this time of year? The other planets and stars all at different phases.
And this is constantly changing because of orbital movement, etc. We
have
circled the sun 4 times before light from Alpha Centauri hits us. God
knows
where it actually is when it does hit us.

If gravity is Newtonian, then there is quite a sizeable angular
relationship
between the gravitational relationship of a point on one object, and the
time that light was emitted from another object striking it. If gravity
moves at the speed of light there is still a sizeable difference. Even
more
so when you figure the time differential of the light coming off an
object
being retransmitted, such as from the planets. Meaning the energy
transfer
time and composition of the surface versus light directly transmitted
from a
star.

So much for the supposed accuracy of astrology.

So, how do scientists take into account this myriad of movement and force
relationships on the macro and micro scales?

The spacetime that is a product of the Earth, orbits with the Earth. So
the "line of action" of gravity is always toward the Earth's (or any other
body's) position now.

David A. Smith

Huh?

I am having trouble grasping that spacetime thing. Could you enlarge on
that a bit?

I was assuming everyday old basic math and physical forces.

"N:dlzc D:aol T:com (dlzc)" N: dlzc1 D:cox wrote in
message news:lI4Fc.4657$nc.1464@fed1read03...
Dear Dave Nelson:

"Dave Nelson" wrote in message
ink.net...
Because of the speed of light, we see the sun, the planets, the stars,
and
the person we are kissing after the fact. The sun is what, 2 degrees
beyond
the point in the sky that we see it? Saturn something like 20 degrees
at
this time of year? The other planets and stars all at different phases.
And this is constantly changing because of orbital movement, etc. We
have
circled the sun 4 times before light from Alpha Centauri hits us. God
knows
where it actually is when it does hit us.

If gravity is Newtonian, then there is quite a sizeable angular
relationship
between the gravitational relationship of a point on one object, and the
time that light was emitted from another object striking it. If gravity
moves at the speed of light there is still a sizeable difference. Even
more
so when you figure the time differential of the light coming off an
object
being retransmitted, such as from the planets. Meaning the energy
transfer
time and composition of the surface versus light directly transmitted
from a
star.

So much for the supposed accuracy of astrology.

So, how do scientists take into account this myriad of movement and
force
relationships on the macro and micro scales?

The spacetime that is a product of the Earth, orbits with the Earth. So
the "line of action" of gravity is always toward the Earth's (or any other
body's) position now.

David A. Smith

Dear Dave Nelson:

"Dave Nelson" wrote in message
ink.net...

"N:dlzc D:aol T:com (dlzc)" N: dlzc1 D:cox wrote in
message news:lI4Fc.4657$nc.1464@fed1read03...

Because of the speed of light, we see the sun, the planets, the
stars,
and
the person we are kissing after the fact. The sun is what, 2 degrees
beyond
the point in the sky that we see it? Saturn something like 20
degrees
at
this time of year? The other planets and stars all at different
phases.
And this is constantly changing because of orbital movement, etc. We
have
circled the sun 4 times before light from Alpha Centauri hits us.
God
knows
where it actually is when it does hit us.
....
So, how do scientists take into account this myriad of movement and
force
relationships on the macro and micro scales?

The spacetime that is a product of the Earth, orbits with the Earth.
So
the "line of action" of gravity is always toward the Earth's (or any
other
body's) position now.

Huh?

I am having trouble grasping that spacetime thing. Could you enlarge on
that a bit?

I was assuming everyday old basic math and physical forces.

I moved your response to the bottom, and trimmed to get to the heart of
what I was responding to.

When you concern yourself about propagation delays, you are no longer
treading on Newtonian ground. This means that relativity rears its head.
And since it is gravity that is of concern, then nothing but General
Relativity (GR) will do.

In GR, spacetime (the array of all the places, and all the *nows*) is the
"extension" of all the mass and energy that is contained in it. So the
extension of the central mass and of the orbiting mass is attached to them.
The line of action is directed at/through the extensions, and not through
some force, with a force carrier.

GR is only one method of describing what we see. Quantum mechanics is
still trying to resolve this "high level abstraction" we call spacetime,
and describe gravity using a carrier particle.

David A. Smith

Thank you. That gives me a glimpse into the logic of GR.



"N:dlzc D:aol T:com (dlzc)" N: dlzc1 D:cox wrote in
message news:hceFc.6592$nc.6430@fed1read03...
Dear Dave Nelson:

"Dave Nelson" wrote in message
ink.net...

"N:dlzc D:aol T:com (dlzc)" N: dlzc1 D:cox wrote in
message news:lI4Fc.4657$nc.1464@fed1read03...

Because of the speed of light, we see the sun, the planets, the
stars,
and
the person we are kissing after the fact. The sun is what, 2
degrees
beyond
the point in the sky that we see it? Saturn something like 20
degrees
at
this time of year? The other planets and stars all at different
phases.
And this is constantly changing because of orbital movement, etc.
We
have
circled the sun 4 times before light from Alpha Centauri hits us.
God
knows
where it actually is when it does hit us.
...
So, how do scientists take into account this myriad of movement and
force
relationships on the macro and micro scales?

The spacetime that is a product of the Earth, orbits with the Earth.
So
the "line of action" of gravity is always toward the Earth's (or any
other
body's) position now.

Huh?

I am having trouble grasping that spacetime thing. Could you enlarge on
that a bit?

I was assuming everyday old basic math and physical forces.

I moved your response to the bottom, and trimmed to get to the heart of
what I was responding to.

When you concern yourself about propagation delays, you are no longer
treading on Newtonian ground. This means that relativity rears its head.
And since it is gravity that is of concern, then nothing but General
Relativity (GR) will do.

In GR, spacetime (the array of all the places, and all the *nows*) is the
"extension" of all the mass and energy that is contained in it. So the
extension of the central mass and of the orbiting mass is attached to
them.
The line of action is directed at/through the extensions, and not through
some force, with a force carrier.

GR is only one method of describing what we see. Quantum mechanics is
still trying to resolve this "high level abstraction" we call spacetime,
and describe gravity using a carrier particle.

David A. Smith

"Dave Nelson" wrote in message
ink.net...
Because of the speed of light, we see the sun, the planets, the stars, and
the person we are kissing after the fact. The sun is what, 2 degrees
beyond
the point in the sky that we see it?

The sun is, on the average, 149.68 million km from the earth. It takes
light, travelling at 300,000 km/sec, about 499 sec (8 min 19 sec) to reach
us. The earth rotates 360 degrees in 23 hr, 56 min, 4.091 sec (86,184.091
sec), or about 0.00417087 degrees per second. In 499 seconds that adds up
to 2.08486 degrees.

That means that, in the time that it takes light to travel from the sun to
the earth, the earth has rotated (making the *entire sky* appear to rotate
in the opposite direction) a little over 2 degrees. This is interesting but
unimportant.

Saturn something like 20 degrees at
this time of year? The other planets and stars all at different phases.
And this is constantly changing because of orbital movement, etc. We have
circled the sun 4 times before light from Alpha Centauri hits us. God
knows
where it actually is when it does hit us.

Just how precisely do you need to know the "actual" position of any of these
bodies? Normal calculations of their position are relative to the 'fixed
stars' - in terms of Right Ascencion and Declination - and compensation for
the rotation of the earth [time] and the observer's location thereupon
[longitude, latitude, and sometimes altitude] are made afterwards, since
they affect all astronomical observables similarly.

If gravity is Newtonian, then there is quite a sizeable angular
relationship
between the gravitational relationship of a point on one object, and the
time that light was emitted from another object striking it. If gravity
moves at the speed of light there is still a sizeable difference. Even
more
so when you figure the time differential of the light coming off an object
being retransmitted, such as from the planets. Meaning the energy
transfer
time and composition of the surface versus light directly transmitted from
a
star.

Gravity is best represented as a scalar field that varies inversely with the
square of the distance from the source. Multiple sources produce fields
that add in a scalar way. Since these fields are radially symmetrical, the
'angular relationship' is almost completely irrelevant - although there is a
current experiment to try to measure 'frame' dragging, an effect predicted
by general relativity on the gravitational field of a rotating body, it is
an incredibly small effect.

So much for the supposed accuracy of astrology.

Excuse me. I thought we were discussing *science*.

So, how do scientists take into account this myriad of movement and force
relationships on the macro and micro scales?

Most are negligible. For example, the effect of the moon's gravity on the
surface of the earth, as observed since ancient times in the tides, is at
most 1/8,800,000 times as strong as earth's gravity. That happens when the
moon is directly overhead. The effect of the sun's gravity is even weaker -
about 1/19,300,000 times as strong as the earth's gravity. Since the sun is
about 406,610 times as heavy as Venus, I expect the average strength of
Venus' effect on the earth to be even weaker - about 1/7,800,000,000,000
times as strong as earth's gravity.

Values this small compared to the primary observable are generally described
as 'negligible' since they are beyond the limit of resolution of any
existing instruments.


Tom Davidson
Richmond, VA