Undeniable wrote:

"Greg Neill" wrote in message ...
"Undeniable" wrote in message
...
Uncle Al wrote in message
...


No it does not. Stuff with zero orbital velocity falls straight down
vs. the fixed stars from any arbitrary height (ignoring wind) If you
look locally you subtract out ground motion and allow for ~1 cm/sec
horizontal Coriolus acceleration varying with latitude.

That's correct and I guess unless one is specific and uses the right
terms, like Uncle AL does, misunderstandings can arise.

The key word here is "fixed stars". If the answer is posed in this
context it's correct. However, in my answer I assumed an instantenuous
relative fix of earth's velocity with respect to a moving sun. This
case is a bit more complicated. Actually, everything is in a constant
relative motion and fixing anything could be hard.

Nah. Velocity may be relative but acceleration is absolute.
One need only adjust the circular velocity to result in a zero
centrifugal acceleration component. This is identical to
making the angular momentum zero and the degenerate straight-
line orbit then necessarily obtains.

Wait a second. Where did you find out that all acceleration is
absolute? In my view this is only due to an idealized situation where
in a local experiment the effect of other matter accelerating in the
universe is null and there is no difference in accelerating a particel
with +a or -a. This problem is still unsolved I think. Newtonian
mechanics and Newton himself adhere to absolute rotation and
acceleretion. But if you ever heard of Mach's principle, there are
other opinions that only relative acceleration is only significant.
This is also the perspective Einstein took.

Drop something.

Displacement of three orthogonal cantilevered weights. Acceleration
is absolute. Oh but wait! We are in free fall orbit! Make three
orthogonal circles of marbles. Observe during one orbital period.
But that's objects! Three orthogonal laser ring gyros.

Both linear and angular accelerations are absolute measurements.

Philosophy: Buy a wrapped wastebasket, bring home, place wrapping in
wastebasket.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
"Quis custodiet ipsos custodes?" The Net!

Grok wrote:
How much force is required to slow us down enough so that the big
splashdown is within 50 years?

The kinetic energy of the earth in its motion about the sun is roughly
9*10^26 Joules. So that much work would have to be done on the Earth to
bring its orbital motion to zero.

Bob Kolker

"Old Man" wrote in message ...
Undeniable wrote in message
m...
"Greg Neill" wrote in message
...
"Undeniable" wrote in message
...
Uncle Al wrote in message
...


No it does not. Stuff with zero orbital velocity falls straight
down
vs. the fixed stars from any arbitrary height (ignoring wind) If
you
look locally you subtract out ground motion and allow for ~1 cm/sec
horizontal Coriolus acceleration varying with latitude.

That's correct and I guess unless one is specific and uses the right
terms, like Uncle AL does, misunderstandings can arise.

The key word here is "fixed stars". If the answer is posed in this
context it's correct. However, in my answer I assumed an instantenuous
relative fix of earth's velocity with respect to a moving sun. This
case is a bit more complicated. Actually, everything is in a constant
relative motion and fixing anything could be hard.

Nah. Velocity may be relative but acceleration is absolute.
One need only adjust the circular velocity to result in a zero
centrifugal acceleration component. This is identical to
making the angular momentum zero and the degenerate straight-
line orbit then necessarily obtains.

Wait a second. Where did you find out that all acceleration is
absolute? In my view this is only due to an idealized situation where
in a local experiment the effect of other matter accelerating in the
universe is null and there is no difference in accelerating a particel
with +a or -a. This problem is still unsolved I think. Newtonian
mechanics and Newton himself adhere to absolute rotation and
acceleretion. But if you ever heard of Mach's principle, there are
other opinions that only relative acceleration is only significant.
This is also the perspective Einstein took.

Undeniable's opinion doesn't have a single empirical leg to stand-on.
Mach's "principle" is not empirically falsifiable. It doesn't even rate
as a theory. Rotation rate is self-referential and absolute; Foucault
pendulum; laser ring gyroscope. Reference to the "fixed stars" is not
necessary. Such references involve non-local measurements whereof
the laws of physics are not guaranteed to be invariant. According to
Einstein and GTR, measurement of deviation of an observer's reference
frame from a gravitational geodesic (free-fall) is self-referential and
absolute. The statement that acceleration is absolute is empirically
falsifiable and is consistent with all observations. [Old Man]

How do we measure acceleration? By measuring a small relative position
change in a relative time change and dividing that again by relative
time change. This is how your empirical observation is made in
principle (In actuallity accelerometers are a bit more complicated but
the principle is the same). Now listen to this: You divide two
relative quantities and you claim the result is an absolute quantity.
Obviously, your cheap syllogism incorporates a high degree of
circularity. Now listen to this one also: A: Laws of motion apply only
in inertial reference frames. B: Inertial reference frames is where
the first law of motion is true. Therefore, Laws of motion apply where
laws of motion apply.

You must be kidding Old Man. I don't care about any of your emprirical
observations and all your cut and paste power, when they implicitely
define the conclusion one gets.

And by the way, one of Einstein's self admitted failures was the weak
link to Mach's principle in GTR.

"DarkMatter" wrote in message
...
On Sat, 13 Sep 2003 15:20:30 -0400, "Greg Neill"
Gave us:

The conclusion holds. DarkMatter has failed to impress.


Such a mechanism as that which you described would make quite an
impression. This planet looks like a ball of liquid or paste at such
levels and scales.

There's no doubt about that. But then this was an entirely
hypothetical exercise, a gedanken experiment if you will,
wherein the normal constraints of physical reality are relaxed
and allowed to assume their ideal; light inextensible strings,
massless pulleys, perfectly rigid spherical planets,
inexhaustible energy sources, perfect measuring devices, etc.

"Undeniable" wrote in message
m...

How do we measure acceleration? By measuring a small relative position
change in a relative time change and dividing that again by relative
time change. This is how your empirical observation is made in
principle (In actuallity accelerometers are a bit more complicated but
the principle is the same).

You measure either displacements for a free-floating body
or the forces required to maintain its relative position.
For rotation a laser ring gyro is the way to go.

All of these measurements can be done in a sealed lab without
reference to the outside world, hence acceleration is an
abolute measure, not relative.

Undeniable's willingness to discard and discount empirical
evidence says much about him.

Littlemanwearingbigboypants announces:

Both linear and angular accelerations are absolute measurements.

Have you been drinking or what? That's nonsense. Dead on arrival.

Absolute means having no comparative characteristics.

Acceleration is a change. That's a comparison to what was direction
or velocity, or both, a moment before. Direction and velocity are
themselves relative. You're spinning your wheels on this one.

The term measure itself implicates a comparison to a standard.

When one begins to consider the mechanisms available to measure
acceleration the relative aspects become even more apparent.

Now go ask someone who really understands such matters what
happens when you write an equation like:

{absolute} = {something other than itself}

Greg Neill wrote:

All of these measurements can be done in a sealed lab without
reference to the outside world, hence acceleration is an
abolute measure, not relative.


wrong.

Undeniable wrote:

"Old Man" wrote in message ...
Undeniable wrote in message
m...
"Greg Neill" wrote in message
...
"Undeniable" wrote in message
...
Uncle Al wrote in message
...


No it does not. Stuff with zero orbital velocity falls straight
down
vs. the fixed stars from any arbitrary height (ignoring wind) If
you
look locally you subtract out ground motion and allow for ~1 cm/sec
horizontal Coriolus acceleration varying with latitude.

That's correct and I guess unless one is specific and uses the right
terms, like Uncle AL does, misunderstandings can arise.

The key word here is "fixed stars". If the answer is posed in this
context it's correct. However, in my answer I assumed an instantenuous
relative fix of earth's velocity with respect to a moving sun. This
case is a bit more complicated. Actually, everything is in a constant
relative motion and fixing anything could be hard.

Nah. Velocity may be relative but acceleration is absolute.
One need only adjust the circular velocity to result in a zero
centrifugal acceleration component. This is identical to
making the angular momentum zero and the degenerate straight-
line orbit then necessarily obtains.

Wait a second. Where did you find out that all acceleration is
absolute? In my view this is only due to an idealized situation where
in a local experiment the effect of other matter accelerating in the
universe is null and there is no difference in accelerating a particel
with +a or -a. This problem is still unsolved I think. Newtonian
mechanics and Newton himself adhere to absolute rotation and
acceleretion. But if you ever heard of Mach's principle, there are
other opinions that only relative acceleration is only significant.
This is also the perspective Einstein took.

Undeniable's opinion doesn't have a single empirical leg to stand-on.
Mach's "principle" is not empirically falsifiable. It doesn't even rate
as a theory. Rotation rate is self-referential and absolute; Foucault
pendulum; laser ring gyroscope. Reference to the "fixed stars" is not
necessary. Such references involve non-local measurements whereof
the laws of physics are not guaranteed to be invariant. According to
Einstein and GTR, measurement of deviation of an observer's reference
frame from a gravitational geodesic (free-fall) is self-referential and
absolute. The statement that acceleration is absolute is empirically
falsifiable and is consistent with all observations. [Old Man]

How do we measure acceleration? By measuring a small relative position
change in a relative time change and dividing that again by relative
time change.
[snip]

BULL****. Acceleration is intolerant of an inertial frame of
reference. An accelerated frame of reference will have internal
force(s) that are trivialy measured without reference to anything
external. Mass will have weight in a non-inertial frame. How much
equipment and ratiocination do you need to see something fall?

You read a book but you do not know what you know.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
"Quis custodiet ipsos custodes?" The Net!

Bill Vajk wrote:

Littlemanwearingbigboypants announces:

Both linear and angular accelerations are absolute measurements.

Have you been drinking or what? That's nonsense. Dead on arrival.

Absolute means having no comparative characteristics.

You must have been a real laugh in bonehead English. How is it going
this time around, Vajk? Mass has weight in a non-inertial frame of
reference. Stuff falls. That is an absolute measurement. You don't
need fixed stars, you don't need calibration. You only need eyes.

Acceleration is a change. That's a comparison to what was direction
or velocity, or both, a moment before. Direction and velocity are
themselves relative. You're spinning your wheels on this one.

Have you been frenching ****Head?

The term measure itself implicates a comparison to a standard.
[snip]

Stooopid beyond words. Temperature is also an absolute measuremnt.
So are mass and charge.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
"Quis custodiet ipsos custodes?" The Net!

In article , "Robert J. Kolker" writes:


Grok wrote:
How much force is required to slow us down enough so that the big
splashdown is within 50 years?

The kinetic energy of the earth in its motion about the sun is roughly
9*10^26 Joules.

Actually, it is more like 3*10^33 Joules.

So that much work would have to be done on the Earth to
bring its orbital motion to zero.

The energy requirements are still the small part of it. Momentum
needs to be conserved as well. The linear momentum of the Earth, at
any given moment, is close to 2*10^29 Ns. Now, the Saturn V first
stage engine (or, rather, cluster of engines) had thrust of about
4*10^7 Ns. So, if you would build about a million of this babies
(never mind where the materials and labor are coming from), they would
have to run continuously for the next 150 million years (consuming an
amount of fuel 10 times larger than the Earth mass) to supply the
required impulse.

Mati Meron | "When you argue with a fool,
| chances are he is doing just the same"