Joe Fischer wrote: On 20 Nov 2005 22:36:40 -0800,
wrote:
Old Man wrote: wrote in message
I would say that gravity is definitely a force. I find
Einstein's assertion that gravity is the result of
space curvature to be absurd. ....

frankinhu is kicking a straw man. He's left out the bit
about time. The real hypothesis is that the acceleration
measured by a freely falling observer is always zero.
The proximity of mass / energy alters the space-time
metric from that of free space.

The reason is that if mass does bend space, then I
would think that it would bend space for all objects
passing through a region no matter the speed or mass.

And time ? A null-geodesic is pure geometry. it depends
only upon the impact parameter. Invariant mass /energy,
m*c^2, gravitates. Kinetic energy, p*c, belongs to the
null-geodesic. It works. Newton doesn't.

WHAT "iNVARiANT mass".?!! WHAT "mass.".?!! GR HAS *NO* "mass".!!
EXHiBiT how any GR mass mathematically RELATEs to GR T_uv = G_uv.

(Snicker) oh, what happened to any sign of GR *ANGULAR* momentum?

OK, I may be missing something

Well GR, *NOW* has ..TWO (2) MiSSiNG-mass ..IT's ONLY TWO (2).!!

You missed a lot, and since you seem to be interested,
no need to miss all the fun.

- but what does the dimension of time
have to do with the warping of space? Let's include time - how
does this make the curvature of space-time dependent on the mass
and speed of the object passing by a more massive object?

For objects smaller than a mountain, mass is not required
in the math. --

insert .."dipstick".!!

-- The reduced formula for gravity is a = GM / d^2
where M is the mass of the overwhelming object (a different
formula is needed for, say, the moon.

But speed is a factor, even if centrifugal force is not
considered. If the shuttle were going as fast as light,
it would travel in an almost straight line.

Let's be clear, suppose we consider the space shuttle in Earth's orbit.
According to Einstein, the shuttle is not experiencing any 'force'
which causes it to circle the Earth.

Neglecting air friction, right. --

$ The interPLANETARY and interSTELLAR ambient MASS:
No ATMOSPHEREs are iNCLUDED in the THEORY of NEWTON or GR.
Newton's work and GR-Tivity DOES NOT include the GRADiENT,
( the DENSiTY gradient ) which EXiSTs around massive ORBs.
The THEORY of NEWTON & GR-Tivity call ALL this a VACUUM.!!

-- But there are other gravity models that also do not use force.

It is simply following the
shortest possible path between any 2 points which just happens to be an
orbit around the Earth. As far as the shuttle is concerned, it is
following a straight path.

$ Read my My lips.!!
ANGULAR momentum pA = planet-like, mass*radius*velocity:

( Notice there is NO quantity for CENTRAL mass in there. )

That is a good way to think of it, but the path is determined
by the speed, if the shuttle and a light beam were to go the same
speed past the sun, the light beam would bend _more_ than
the path of the shuttle, twice as much, in fact.

There's NO EARTH-mass in GR.!! There's NO SPACE-time curvature in GR.!!
HOWEVER, if there COULD BE a mass in GR ..NO Newtonian LiMiT (i.e. if),
THEN, subsequently, the EARth's *GR-WORLD-line-POiNT-mass* will "curve"
the trajectory of ANOTHER *GR-shuttle-WORLD-line-POiNT-_TEST_-mass*, iN
the GR-space, ON (..not, ABOVE) the GR-surface, of GR-WORLD-line-POiNT.

BUT, where-as Newton's TEST-mass m1 (in G*M1*m1) has a CALCULATED field
...mathematically speaking NOTE the corresponding GR-TEST-mass does NOT.
[Mathematically CENTRAL mass M1 "attracts" TEST m1, but m1 doesn't M1.]

[That's ANOTHER thing.!! There's NO centro-SYMMETRY in GR THEORY, duh.]

[Again iRONiCALLY, there is NO mass mathematically RELATED to GR T_uv.]
[Again PROFOUNDLY, there is NO mass-RELATED GR-SPACE-time "curvature".]

[Again, ADAMantLY, there is NO GR-mass-RELATED SPACE-time "curvature".]


Now if the astronaut in the shuttle shines a laser pointer out the
front window, it should also follow the straight path, which should
also correspond to an orbit around the Earth if Eienstein is correct.

No, General Relativity gives the same answer as Newton
for "weak" gravity like the Earth. But the light beam moves
too fast to be affected a noticeable amount.

But of course, it doesn't. It shines as a tangent to the surface of the
Earth and does not follow the orbit of the shuttle. It might bend a
tiny bit towards the Earth since light has some attraction to gravity,
but not nearly the amount that the shuttle observes.

Speed is the reason.

LiGHT velocity c is NOW a MATHEMATiCAL constant ..just as is, pi.!!
LiGHT velocity c is NOW a, transcendental, MATHEMATiCAL constant.!!

LiGHT velocity v VARiEs, inversely, WiTH the PATH particle COUNT.!!

Now what does time or space-time have to do with this phenomenon?

Spacetime is the mathematical topology of gravity. It is
used without being a physical entity.
It is convenient to talk of bent or warped spacetime, but
as of now, it is only math, the mechanism or mode of operation
is not known as a fact.

What
are the calculations that allow you to say that the observed curvature
changes depending on the mass and speed of the object in question? Why
does the shuttle follow the curvature of the Earth, while the light
beam follows a straight line tangent? They are both experiencing
exactly the same gravitational fields. They should be experiencing
exactly the same spacetime as well.

In low Earth orbit, the shuttle "falls" about 15 feet in one second,
and from that new tangent, it "falls" another 15 feet the next second.
At 18000 MPH, it travels about 25000 feet in one second, but
light "travels" 186000 miles in one second, so gravity has less time
to act on objects moving faster.

I have a standard college physics text (Physics, Douglas Giancoli), and
only has 1 paragraph --

$ Communists and dyslextics fall iDENTiCALLY.!!
..AND its TRUE, that RiGHT and LEFT handed TWiNs,
arriving BACK from the SAME SPACEtime trip, will:
(A) Arrive BACK at somewhat DiFFERENT TiMEs or;
(B) LEFTY will be turned COMPLETELY iNside OUT.!!

[ The ONLY way to KNOW ..if (B), is TAG underwear labels.!! ]

-- beyond the rubber-sheet analogy with absolutely no
justification for this spacetime bending. Another book (Einstein's
Universe, Nigel Calder) simply says the mathematics of tensor calculus
are way beyond explaining in the text. I say the whole idea is a
load of crap!

Not hardly, but neither is it fully understood.

So prove me wrong - show me how this spacetime gravity thing is
supposed to work without referencing the rubber sheet analogy, I'd
be really curious in finding out. Show me the calculations that
predict the path of the space shuttle in orbit and the path of
light at the same height. And then explain why the are different.
The only way I can figure it does this is if spacetime warps
differently for different objects passing by - which seems total
nonsense.
Here is a link you can double click;
http://www.bun.kyoto-u.ac.jp/~suchii/gen.GR2.html

In 1911, Einstein predicted that light would "fall" in
gravity, but he got only half the correct anount, he worked the
problem as if it were Newtonian gravity. --

[Mathematically speaking GR steals and DOCTORs Newton's 3-d TEST-mass.]
[Mathematically speaking GR steals and DOCTORs Newton's 3-d ..MERCURY.]
[Note GR does NOT enter ANY OTHER data input, mathematically speaking.]

-- In 1915, with the formalized version of General Relativity, he
predicted the correct amount.

A far easier explanation is that gravity is a constant force which
tugs on all objects.

That is what Newton said, but only in the math, to make
it work with his mechanics.
Actually, Galileo and Newton used gravity to establish
units used in Newtonian mechanics used by most engineers.

Objects which have more mass or velocity can escape
this constant force more effectively.

Velocity, yes, but if the mass is more than one percent
of the Earth, it requires a different formula. --

-- While "force" is used, it is the relative acceleration that
is wanted, then Newton would have to calculate the acceleration.
For objects as big as the moon, a formula that looks
like a = G (M + m) / d^2 is used, rather than F = GMm / d^2.

$ NOT "that N-body systems decay into 2-body ones." ..but
that NEWTON simplified N-bodies to PROFOUNDLY TWO (2).!!
Newton PROFOUNDLY simplified N-bodies to just TWO (2).!!

THOSE equate for BiNARY systems, you PROPER idiot.!!

So light, being very fast and
light, escapes very easily, while the shuttle, being massive and slow,
is confined to circling the Earth.
fhugravity

Sorry, but you have the wrong concept, which does not
even agree with Newtonian gravitation, let alone General Relativity.

If you can find the book "The Attractive Universe" by Valens
in a book store on on the Internet, buy it, it is written at the 8th
grade level, but has many interesting drawings and high speed time
lapse multiple exposure photographs describing what gravity does.
It also has a lot of useful and interesting information about
gravity, the tides, orbits and simple Newtonian formulas.

General Relativity is the most precise mathematics for gravity,
but it is not the easiest or the most clear model to use.
It does simplify the physics of gravity, because it makes
freefall and orbits nothing but inertial motion, where objects
follow geodesics in spacetime.

No GENERAL THEORY of RELATiViTY c^4 / G ..it's ALL NEWTON's.!!
The PLANCK c^4 / G is NOT mathematically related to GR G_uv.!!
The NEWTON c^4 / G is NOT mathematically related to GR T_uv.!!

PROFOUNDLY, GR's G_uv = T_uv is NOT "RELATED" to Newton's G.!!

brian a m stuckless

If you are really interested, then the study of Einstein's
Principle of Equivalence (which is described in the link above).
It provides a useful way to view surface gravity, although
in 1911, it was only valid in a small area like a room.
But there is a chance, the more you read, the more
questions you will have..

Joe Fischer.