## Gravity

This is not an everything goes forum, but rather a place to ask questions and request help for developing your ideas.

### Gravity

Gravity
==
1 - Newton's gravity
Newton explained gravity from Earthly point of view
( as a boy playing on the beach of an ocean)
Newton explained gravity as interaction between two bodies
in the flat Solar system ( no curved, no distorted, no warped space )
2 - Einstein's gravity
Einstein explained gravity from Cosmic point of view
( as a boy flying at speed of light )
Einstein explained gravity when there is only one single body (gravity-masses)
These gravity-masses (of Sun) can distort the flat continuum of the Universe
only in Its very small , local region
Not the all flat continuum of the Universe was curved, only a small,
local region was warped and twisted around the Sun
3 - What is caused the light / photon to change their straight way
in the Universe: the gravity-masses or the warm / hot atmosphere
temperature around Sun ?
( the cold light / photons automatically flow in the warm / hot region,
like a cold air enters in your warm room when window is opened)
4 - It is very possible that light / photons change their way by sum
of two factors ( the hot temperature + gravity-masses ) and this
one factor ( the hot temperature of accelerated gravity-masses )
keeps a gravity-Sun be our ''living-Sun''
=====
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socrat44
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### Re: Reach for the Stars

socrat44 wrote:Einstein explained gravity when there is only one single body (gravity-masses)These gravity-masses (of Sun) can distort the flat continuum of the Universeonly in Its very small , local regionNot the all flat continuum of the Universe was curved, only a small,local region was warped and twisted around the Sun

This is not consistent with Newton's inverse square law or Einstein's field equation.

The gravitational field of the tiniest quantum of mass-energy extends indefinitely (i.e. as far as its light cone reaches).

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### Re: Reach for the Stars

Faradave » March 10th, 2019, 9:11 pm wrote:
socrat44 wrote:Einstein explained gravity when there is only one single body (gravity-masses)These gravity-masses (of Sun) can distort the flat continuum of the Universeonly in Its very small , local regionNot the all flat continuum of the Universe was curved, only a small,local region was warped and twisted around the Sun

Faradave » March 10th, 2019, 9:11 pm wrote:This is not consistent with Newton's inverse square law or Einstein's field equation.

1 - Newton's inverse square law is right to explain
the interaction between two (2) gravity-bodies.

2 - Einstein's GRT equation is right to explain
effect of gravity for one (1) single gravity-body.

Faradave » March 10th, 2019, 9:11 pm wrote:The gravitational field of the tiniest quantum of mass-energy extends indefinitely
(i.e. as far as its light cone reaches).

Hmm . . . That's funny...
===
socrat44
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### Re: Tedium of the Medium

That's beside my point that gravity, like electromagnetism is a "long-range" (i.e. indefinite extent) force. This is quite different than the strong & weak nuclear forces which are very "short-range" (generally, within a nucleus).

Gravity acts indirectly by altering its medium (the space-time continuum).

Einstein describes how mass-energy (M) alters the ability of the continuum to maintain separation (often referred to as "curvature"). Every passing object, regardless of its own mass (m), responds to this same alteration by accelerating toward the original body to the same degree.

Newton gives describes the mutual, attractive gravitational forces on two different objects (M & m) as F = GMm/r². But he also gives F = ma. So the acceleration of m is a = F/m = (GMm/r²)/m =GM/r², which is the same for all objects m passing M, regardless of the size of m. (a depends only on M because m cancels itself out.)

The descriptions essentially agree. Hmm...

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### Re: Gravity

My conclusion:
1 - gravity is the weakest ''force'' in nature
2 - gravity is about 10^36 times weaker than EM force
3 - ''gravitational waves'' distort space only by about a factor of 10^-20
4 - gravity is only a local effect in the  universe
5 -  the concept ''Gravity'' cannot be used to the universe as whole
(for example:
Gravity cannot gather all matter of universe into ''singular point'' for
''big-bang'' as ''modern philosophy of science''  teach us today)
========
socrat44
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### Re: Cluster Bluster

socrat44 wrote:4 - gravity is only a local effect in the universe

I don't know why you're fixated on "local" but our galaxy is part of the Virgo Supercluster, which is gravitationally bound at 110 million light years across!

socrat44 wrote:Gravity cannot gather all matter of universe into ''singular point'' for ''big-bang'' as ''modern philosophy of science'' teach us today)

It can when gravity is not countered by other forces, including dark energy, which science is still trying to understand. The reach of gravity is indefinitely long range. In some ways it is more far reaching than EM.

"Gravitational waves can penetrate regions of space that electromagnetic waves cannot. They are able to allow the observation of the merger of black holes and possibly other exotic objects in the distant Universe. Such systems cannot be observed with more traditional means such as optical telescopes or radio telescopes, and so gravitational wave astronomy gives new insights into the working of the Universe. In particular, gravitational waves could be of interest to cosmologists as they offer a possible way of observing the very early Universe. "

Like EM, G waves cross space and time but light could not emerge from the Big Bang until about 100,000-200,000 years after because of density-related opacity. Gravity is not so restricted. "Weak" does not mean "local". "Strong" does not mean "far-reaching". The strong force is much, much stronger than G (x 1038) yet is extremely local (10-15 m).

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### Re: Gravity

Faradave is right about the universe wide, long reaching effect of gravity. A spinning gyroscope is not affected by local gravitational forces because it orients with the overwhelmingly more powerful gravitational force of the more than 200 trillion galaxies that surround us in all directions. We only notice the local effects of gravity and discount the greater effect of gravity from the distant galaxies because it is uniform in all directions much like air pressure.

I don’t like to think of gravity as curved spacetime because it is hard to imagine how either space or time can curve so I prefer to think of gravity as shorter space and slower time. Light curves around local masses like the sun because the part of the light beam closest to the massive body is moving through shorter distances at a slower clock rate than the more distant parts of the beam. Measured distances become shorter and clocks tick slower in a gravitational field.

socrat44 » March 10th, 2019, 12:44 pm wrote:
3 - What is caused the light / photon to change their straight way
in the Universe: the gravity-masses or the warm / hot atmosphere
temperature around Sun ?
( the cold light / photons automatically flow in the warm / hot region,
like a cold air enters in your warm room when window is opened)

The curving of light around the sun is due to a gravitational effect that extends far beyond the atmospheric envelope of the sun and light is not effected by heat radiation. Radiant heat is just another form of EM radiation no different from light except that it has a longer wavelength and crossing beams of EM radiation don’t interact.
bangstrom
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### Re: Gravity

My understanding is that the earth is actually drawn gravitationally towards the sun's instantaneous now-position, not drawn to a location where the sun used to be 4 minutes ago. I heard a rumor that if there were such a lag, the solar system would not be stable and the planets would have been flung away long ago.

However, this rumor is almost always attached to a stipulation in a colored box in the margin. If there are any changes to the sun, the gravitational effects of those changes are transmitted towards the earth only at the speed of light.

(I'm not actually sure of any this. Just reporting things I remember.)

hyksos
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### Re: Gravity

I have heard a similar theory about gravity and there is a name for the paradox but I don’t recall what it is. There is also another theory that the speed of gravity is c but it leaves behind a static field of curved spacetime that points directly to the source rather than where the source was at some retarded point in time so a satellite responds locally to the “now” position rather than wait for a gravity signal to arrive. As I recall, the only difference from your account was that a satellite responding to a time retarded signal should spiral inward rather than be flung outward and a signal from the sun is retarded by 8+ min.

There was a recent measurement for the speed of gravity waves based on the decay of the the Hulse-Taylor binary system that calculated the speed of gravity waves to be essentially the same as c. About every two years someone finds a clever way for measuring the speed of gravity waves and they find gravity to have the same speed as c but later analysis reveals that they were inadvertently measuring the speed of light. It is difficult to distinguish a true “instant” signal from a static gravitational field resulting from a gravity wave traveling at c.
bangstrom
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### Re: Gravity

GRT - 1915 / my opinion /
===
The basis of modern cosmology is Einstein's GRT
GRT equations predict:
1- in the early moment the entire universe was contained in
a ''singularity'', where  the mass was enormous, the volume was zero,
the density was infinite.
2 - somehow this ''singularity'' was ''expanded'' to the sizes of a star
3- the gravity-masses of star distorted the absolute ''spacetime'' of the universe.
4 - the quantum particles change their straight way moving  near star's masses.
5 - all billion stars in billion galaxies obey Einstein's ''GRT'' scheme.
6 - all billion and billion galaxies are only about 5% of all mass/energy
in the absolute ''spacetime'' continuum.
======
socrat44
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### Re: Gravity

socrat44 » March 15th, 2019, 2:36 am wrote:  GRT - 1915 / my opinion /
===
The basis of modern cosmology is Einstein's GRT
GRT equations predict:
1- in the early moment the entire universe was contained in
a ''singularity'', where  the mass was enormous, the volume was zero,
the density was infinite.

I have my personal reservations about the general consensus of modern cosmology but your summary appears to be largely correct with the understanding that there is still debate about some of the finer points.

The “singularity” was the entire universe at the time (it was the whole “Shebang) and it expanded from a universe of unimaginable density to a universe of lesser density and it continues to expand to the present day. If we could step outside the early universe and view it from the perspective of our present highly expanded universe, it could be described as a universe the size of one of our stars but it has never been less than the entire universe.

socrat44 » March 15th, 2019, 2:36 am wrote:2 - somehow this ''singularity'' was ''expanded'' to the sizes of a star
3- the gravity-masses of star distorted the absolute ''spacetime'' of the universe.

The conditions within the early universe were far to extreme to permit the formation of stars. Gravity is “spacetime” itself and it is that spacetime itself that is expanding to a less dense state. Gravity is the curved spacetime of the universe. Gravity is not limited to the local vicinity of stars or any other ponderous bodies. It is the all pervasive thing we call spacetime.

socrat44 » March 15th, 2019, 2:36 am wrote:4 - the quantum particles change their straight way moving  near star's masses.

Spacetime in the early universe was highly curved and curved spacetime is gravity. The two are one and the same. Particles and all massive bodies follow the curved geodesics of spacetime (gravity) so as the universe expands the paths of particles become less curved. A “straight line” in space follows the curved geodesic of the universe itself with local distortions around massive bodies. As the universe expands, the “straight” line paths of particles become less curved.

“Straight” lines are lines that follow the curved geodesics of the universe. There is no such thing as a straight line as imagined in Euclidean geometry. “Straight” lines curve away from the curved geodesics of the universe in the vicinity of stars and all other massive bodies but there is no such thing as a “straight” line in our curved universe. A line that appears as straight to one observer will appear curved to observers outside that observer’s reference frame.
bangstrom
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### Re: Gravity

bangstrom » March 13th, 2019, 2:53 am wrote:
There was a recent measurement for the speed of gravity waves based on the decay of the the Hulse-Taylor binary system that calculated the speed of gravity waves to be essentially the same as c. About every two years someone finds a clever way for measuring the speed of gravity waves and they find gravity to have the same speed as c but later analysis reveals that they were inadvertently measuring the speed of light. It is difficult to distinguish a true “instant” signal from a static gravitational field resulting from a gravity wave traveling at c.

It is good to mention binary systems here because this will take us where we need to go next.

The idea that the sun is planted in the center by God and the planets revolve around it -- well, that's a good approximation. The sun is very massive and the approximation is good, but it is not the truth. The reality of the situation is that Jupiter and the Sun revolve in a dance coordinated around their shared center-of-mass. The earth (and other inner rockies) spin around in tight orbits that slightly wobble the ideal dance between Jupiter and Sun.

I have a personal way of understanding why it would be the case that the earth is attracted to where the Sun is, not where it was 4 minutes ago. While my personal ideas are not authoritative, they may help you too.

My visualization is that the earth/sun system is in free-fall towards the center of the Milky Way. In this sense the planets of the solar system are in a "co-moving" coordinate system. In Special Relativity, you might call it a reference frame. For better or worse, our universe makes a huge distinction between constant linear motion and acceleration. Consistent with our experience of being attached to the outer skin of the earth, we can perform no measurement inside of a free-fall reference frame that would indicate to us that we are in motion. Such "experiments" would include the nagging and repeated observation that we seem to be gravitationally drawn towards a location in space where the sun was 8 minutes ago. We do not observe this! That "experiment" would indicate the solar system is in motion and so that experiment fails.

So the gravitational field has this "aspect" where no experiment in a comoving reference frame indicates that the entire system ("traincar") is in motion. Ironically, the electromagnetic field also has this "aspect". Magnetic and electric field interactions are instantaneous (provided the charged particles are in a co-moving reference frame.) But changes to either particle are transmitted at c.

In another sense, there should be nothing ironic about this at all. I lock you in a deep underground bunker, and ask you to perform an experiment that would confirm the speed that the sun is falling to the center of the Milky Way. Or if the orbit is too stable, do something that indicates the circular velocity of the sun. There is no experiment you can perform in your bunker to measure this. S-R prohibits such an experiment.

hyksos
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### Re: Gravity

If everything was started from ''singularity'' then we need
to pay more attention on concept  ''singularity''.
#
''Singularity'' is not only ''a point''.
''Singularity'' is also ''a place''.
''A place'' where  the mass is enormous, the volume is zero,
the density is infinite, and the time is zero.
Somehow  this ''singularity place'' was ''expanded''
What is the reason of this  ''expansion'' ?
In my opinion, it can be only a Zero point energy.
======
socrat44
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### Re: Gravity

hyksos » March 15th, 2019, 1:59 pm wrote:
My visualization is that the earth/sun system is in free-fall towards the center of the Milky Way. In this sense the planets of the solar system are in a "co-moving" coordinate system. In Special Relativity, you might call it a reference frame. For better or worse, our universe makes a huge distinction between constant linear motion and acceleration.

I would add that the Milky Way is also in free-fall towards the gravitational center of the universe. From the perspective of our galaxy, or any galaxy, the gravitational attraction from the combined massive bodies in the universe is equal in all directions so the Milky Way is already at the gravitational center of the universe, as are all the other galaxies, where they remain ‘motionless’ in free-fall. Any force causing a ponderous body to move away its free-fall, motionless ‘center’ of the universe is detected as acceleration and resistance to this force is called inertia.

An inertial reference frame in SR is not the same as a co-moving coordinate system. Different reference frames can have their individual “free-fall” co-moving coordinate systems.

hyksos » March 15th, 2019, 1:59 pm wrote:
Consistent with our experience of being attached to the outer skin of the earth, we can perform no measurement inside of a free-fall reference frame that would indicate to us that we are in motion. Such "experiments" would include the nagging and repeated observation that we seem to be gravitationally drawn towards a location in space where the sun was 8 minutes ago. We do not observe this! That "experiment" would indicate the solar system is in motion and so that experiment fails.

But the solar system IS in motion about the sun. In theory, the solar system should not be drawn to where the sun was 8 minutes ago but I don’t see how this “experiment” supports the theory.
The planets and sun may all be in free-fall but they occupy slightly different reference frames both gravitationally and motion wise.

hyksos » March 15th, 2019, 1:59 pm wrote:
So the gravitational field has this "aspect" where no experiment in a comoving reference frame indicates that the entire system ("traincar") is in motion. Ironically, the electromagnetic field also has this "aspect". Magnetic and electric field interactions are instantaneous (provided the charged particles are in a co-moving reference frame.) But changes to either particle are transmitted at c.

I consider “changes” to be another word for “interactions” and EMF interactions (changes) to be instantaneous but we can never observe them as instantaneous whenever the interactions are separated by distance. Events separated by distance are also separated by time “spacetime” at the rate of one second for every 300,000 km of distance. This makes c a space/time dimensional constant rather than the speed of EM interaction. This also applies to gravity where gravity is also instant but we can never observe it to be instant.
bangstrom
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### Re: Gravity

I know.
===
1 - i know: Newton's gravity describes that two objects with mass
feel toward each other.
2 - i know:  Einstein's gravity describes that a single object with mass
distorts the space and time around it in such a way that causes
light in the vicinity to curve toward that object.
3 - i know: Newton's and Einstein's matter are less than 5% in the universe
4 - i know: these ≈ 5% of matter can bend only ≈ 5% of universe's space
5 - i know: the rest space of the universe (+ 95%) is flat continuum.
6 - i know: this simple arithmetic is hard to adopt.
============
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socrat44
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### Re: Gravity

Gravity: Spinning Galaxies and Dark Matter
==
Measurements showed that the galaxies were spinning
faster than was predicted by how many stars they contemned.
In other words, the stars should be flying off the edges of the
galaxies -- the gravity law should not be working.
In order to explain the high rotation speed (and save the gravity law
in each galaxy) astronomers needed to add a huge amount of
''dark matter'' to each galaxy  in their calculation so all the stars
held together.
Dark matter helps normal matter clump together.
Dark matter  saves gravity law in each galaxy.
Without dark matter gravity law doesn't work in galaxy.
#
Question remains: what is dark matter made of ?
Short answer: we have no idea.
======
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socrat44
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### Re: Gravity

socrat44 » March 28th, 2019, 11:15 am wrote:Gravity: Spinning Galaxies and Dark Matter
==
Measurements showed that the galaxies were spinning
faster than was predicted by how many stars they contemned.
In other words, the stars should be flying off the edges of the
galaxies -- the gravity law should not be working.
In order to explain the high rotation speed (and save the gravity law
in each galaxy) astronomers needed to add a huge amount of
''dark matter'' to each galaxy  in their calculation so all the stars
held together.
Dark matter helps normal matter clump together.
Dark matter  saves gravity law in each galaxy.
Without dark matter gravity law doesn't work in galaxy.
#
Question remains: what is dark matter made of ?
Short answer: we have no idea.
======

Dark matter is needed to add so all the stars held together.
Dark matter helps normal matter clump together.
Dark matter saves gravity law in each galaxy.
Without dark matter gravity law doesn't work in galaxy.
#
In other words, there are two kinds of gravity in each galaxy:
a) normal (Newton - Einstein ) matter gravity and
b) dark matter gravity.
Dark matter gravity supports to keep balance of matter in
each gravity system.
=====
socrat44
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### Re: Gravity

Gravity: Dark matter + Antimatter
=
1 - dark matter is 27% in universe
2 - normal matter is 5% in universe,
it means anti-matter must be also 5%.
So, dark-matter cannot be anti-matter
#
1 - dark matter has stuff and therefore
must feel gravity (takes part in gravity process)
But it doesn't reflect light or give off light
It means dark matter doesn't have electromagnetic
force (doesn't have electric charge)
2- we don't know what kind of particles it is made of
3 - anti-matter is made of anti-particles
Anti-particles have their own pure electric charge.
So, dark-matter cannot be anti-matter
#
1 - if dark matter doesn't have electric charge (neither normal,
nor anti-normal) then it is passive stuff
2 - the gravity-matter is the weakest force
(it is about 10^36 times weaker than the EM force)
3 - antimatter force is also 10^36 stronger than dark-matter
It means, anti-force has enough power to manipulate
with passive dark-matter to create black - gravity effect
#
To create ''normal-gravity'' is needed energy and matter
Antimatter is source of energy and dark-matter is source of mass
Their interaction can (with logW of probability) create black- gravity effect
With time black-gravity evolves into normal-gravity effect
=====
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socrat44
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### Re: Gravity

Cosmology: two ideas

The  ''big bang'' idea explains how hot singularity
created billions hot stars when the rest of the universe
is extremely cold
Big bang says nothing about where did ordinary matter
come from (it says: chickens come from eggs and eggs
come  from chickens:  singularity <---------> big bang )

This idea contradict ''dark matter - antimatter'' idea
#
To save gravity as universal  law for galaxies the dark matter
was invented
Dark matter is extremely cold stuff
Dark matter is passive / neutral stuff (doesn't have electric charge)
This cold stuff is much more in universe than normal matter
Dark matter is seed of normal matter and of formation of stars.
#
To create gravity (stars) needs not only matter but also energy.
Quantum antiparticles ( antimatter) are cold stuff that carry itself
enormous pure energy (according to Dirac: -E=Mc^2)
Each antiparticle 10^36 times stronger than dark matter particle
(graviton) and therefore each antiparticle can manipulate with
huge stuff of dark matter
Antiparticles (through so called ''quantum fluctuations'' ) involve
dark matter in process which was ended by creation of all visual
stars, galaxies  . . . etc
/ my opinion /
======
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