[pasala (OP)]

Forget light for a moment and consider a tennis ball.
Spaceman in no gravitational field (or freefall) feels weightless. If they push a tennis ball away from them it will go in a straight line to the opposite wall (as would light).
Now the spaceship starts to accelerate, the ‘bottom’ wall of the ship moves up and pushes against the feet of spaceman so he has to use leg muscles to stand; if he now pushes the tennis ball away it will fall towards his feet, exactly the same as if he were standing on earth in a gravitational field. Acceleration and gravity are equivalent.

Here, Einstein's idea's are moving around Newton's inverse square law.  The space ship is far away from the mass, deep in space, still there is gravity, how?.  Finally, he came to know a conclusion that it may be due to acceleration.  This is one  of the incorrect ideas of Einstein.

Now a days, science developed a lot.  We are sending our space ships to Moon and also coming back to Earth.  For that our space ships are going to ISS regularly.  Initially, at the time of departure from Earth, things inside the cabin of the space ship behaves differently, and it is not due to acceleration 9.81 m/s.  In case, if the space ship accelerates less then 9.81 m/s, in such case, there is a chance for the space time of the cabin to inter act with the outside space time and thus gravity coming down.  If the space ship accelerates more than 9.81 m/s gravity field inside the space ship remains intact.   

Now, let us assume that space ship started from the ISS, inside the cabin, if you push the tennis ball it will not fall to the the ground but move straight.  Cabin of the spaceship is locked in a non-gravity, doesn't mean that there is no gravity but it is acting differently or weak gravity.  The crew inside the cabin need not use muscle power to stand. 

In my view, Gravity is a field present on Earth. A part of this field is packed in the cabin.  However it is surprise to see, this field in a small area such as cabin giving same results.  Gravity never increases due to acceleration and there are no instances or proof as such.

Ok, if the space ship accelerates from ISS and if there is gravity due to acceleration, I am sure that I will accept that mine hypothesis is wrong.  What is there.

[Kryptid]

The space ship is far away from the mass, deep in space, still there is gravity, how?

There isn't, as we've already told you.

Gravity never increases due to acceleration and there are no instances or proof as such.

When did anyone say that it did?

[pasala (OP)]

All the above posts about "What is Gravity", make me wonder whether a similar question could be asked, such as:

What is the "Strong Nuclear Force".

This "force", as far as I understand it, makes protons in the nucleus of an atom gather together.  Despite the protons' mutual positive charges.  Which ought electrically to repel them from each other, and make them fly apart.

This "Strong " force seems to be accepted as a "Fundamental Force of Nature".  Without needing an
explanation.

If this is so, can't the "Gravitational"  force , which makes atoms gather together, also be accepted as a "Fundamental Force of Nature".   Without needing an explanation?

Why can't we  treat "Gravity" like the "Strong Force" -  ie, as just the way things are in the Universe?

What you are saying is 100% correct.  There is no strong nuclear force or weak gravity force, there is only one force.  The truth will come out if science develops.  Let us wait for the same.

[Kryptid]

There is no strong nuclear force or weak gravity force, there is only one force. 

How can that be the case when they behave so differently?

[Janus]

Let's compare this scenario to waves created by a ship moving in a pond. Scenario presented on your animations shows a situation, where a wave is propagating perpendicuralry to the motion of a boat in a pond, which moves together with the boat in relation to a stationary observer - it propagates perpendicularly in the frame of boat and diagonally in the frame of stationary observer. However wave propagating perpendicuralry to a moving boat in a stationary pond will behave differently - it will propagate perpendicularly to the moving boat in the frame of stationary bystander and diagonally in the frame of the boat.

If the motion of light is not affected by the motion of it's source in the frame of a stationary observer, then it's the second option (with stationary pond), which should be applied to this scenario.

With the pond, the waves travel relative to the water which acts like a medium.  There is no medium for light traveling in a vacuum.  So the waves made by a boat in the pond is not a valid analogy.
But neither does light behave exactly like a bullet fired from a gun according to Newtonian physics.  A bullet fired from a moving train has its speed increased relative to the ground as measured from the ground, light does not. While the observer would measure it traveling at an angle along a diagonal, they would also measure it as moving at c along the diagonal.
You can also examine the train scenario by reversing the roles. Put the source on the ground and have the observer on the "moving" train.   The train observer will measure the light as traveling at a diagonal relative to the train.  In other words, it doesn't matter which one, the source or observer, you assume is moving, the observer observes exactly the same thing, and he can't tell which one is "really" moving. The very idea of who is "really moving" and who is "really stationary" is meaningless.

[jeffreyH]

What you are saying is 100% correct.  There is no strong nuclear force or weak gravity force, there is only one force.  The truth will come out if science develops.  Let us wait for the same.

I think you have a typo. You misspelled farce.

[Colin2B]

Ok, if the space ship accelerates from ISS and if there is gravity due to acceleration, I am sure that I will accept that mine hypothesis is wrong.  What is there.

You accept that in the ISS the astronauts are in freefall and feel no gravitational force, this will be the same in a spaceship alongside.
If that spaceship accelerates at 9.8m/s² the astronauts will feel a force pushing them towards the back of the ship and that force will be the same as that due to gravity on earth. It is not gravity (which is due to the attraction between masses) but it is equivalent to gravity.
This has been proven by astronauts travelling to and from the ISS.

[pasala (OP)]

Please remember, these are not mine thought experiments, but Einstein’s only. 

Now if you allow a light beam from outside, through a hole of elevator and observe where it struck, it all depends on the acceleration and velocity of the  elevator though source is relative.  In other words, unless there is a change in elevator, up, down nothing change can be deducted.
1.   If there were no relative motion or relative acceleration the light beam would appear to
         travel straight across.
2.   If there were relative velocity the light beam would move in a straight line, but would be
         displaced from going directly across.
3.   If there were relative acceleration, the light beam would follow a curved path, relative to
        acceleration.

By these thought experiments that Einstein came to an idea that Gravity bends light.  But it is surprise to see:
01   As long as the elevator is at rest or stationary on the ground, light beam moves out from
        one hole to other hole.
02   It is only after movement or change in the elevator, acceleration or velocity that light is
        bending.
03   But, it is not clear how Einstein came to a conclusion that gravity bends light.

I would like to propose:
From the Einstein thought experiments itself it is clear that light is bending only after change or movement in the elevator.  It is true that as long as the elevator is on the ground, light beam moves straight, from one hole to the other hole. 

As the elevator attains acceleration, what is causing or affecting light beam to bend.  This is not happening in normal course when it is on the ground.  Well, scientifically it is proved that something is changing when the elevator is accelerating. 

It is also proved that even in closed elevator Mr. X’s weight continues to be 75 kgs only as that of on Earth.  It is also scientifically proved that some thing is changing in the closed elevator when it moves, which I propose it as “Gravity field”.   As the elevator accelerates forward, gravity field density is increasing at the bottom.  Gravity while moving downwards is bending the light. 

Basically, Gravity is not bending light, it is the light beam flowing or moving according to the flow or movement of Gravity.  It is an indication of change in the Gravity field. 
 
It is proved that starlight passing near a significant mass, such as the Sun, were bent by gravity.

If the Gravity field of Sun is at rest or stationary, starlight is not bent, moves out straight.  Since Gravity is moving, path of the light is changed. 

Light bending is only an indication of movement or change of Gravity field.

Yours
Psreddy

[pasala (OP)]

There is no strong nuclear force or weak gravity force, there is only one force.

How can that be the case when they behave so differently?

What ever you are saying is truth.  But I am talking about future.  In my view, not only Gravity, several other theories will be re-written in future.  It may take lot of time, still I am fully confident that it will be proved that only "one force" exists.

[Colin2B]

As long as the elevator is at rest or stationary on the ground, light beam moves out from  one hole to other hole.

In the thought experiment the elevator is on the ground and so it is in a gravitational field. The light will not go out of the other hole, it will hit the wall below the hole.
You do not need a changing gravitational field to bend light.
In the experiment where the gravity of the sun bends starlight the sun’s gravitational field does not change.

[pasala (OP)]

Ok, if the space ship accelerates from ISS and if there is gravity due to acceleration, I am sure that I will accept that mine hypothesis is wrong.  What is there.

You accept that in the ISS the astronauts are in freefall and feel no gravitational force, this will be the same in a spaceship alongside.
If that spaceship accelerates at 9.8m/s² the astronauts will feel a force pushing them towards the back of the ship and that force will be the same as that due to gravity on earth. It is not gravity (which is due to the attraction between masses) but it is equivalent to gravity.
This has been proven by astronauts travelling to and from the ISS.

Equivalent to gravity or something is not gravity.  As said by Newton, same medium is present on Earth as well as in space.  It is the density of this medium that matters.

[pasala (OP)]

As long as the elevator is at rest or stationary on the ground, light beam moves out from  one hole to other hole.

In the thought experiment the elevator is on the ground and so it is in a gravitational field. The light will not go out of the other hole, it will hit the wall below the hole.
You do not need a changing gravitational field to bend light.
In the experiment where the gravity of the sun bends starlight the sun’s gravitational field does not change.

Once again I reiterate that these are Einstein  thought experiments only.  It is known and proved fact that Sun is rotating on its axis. 

Ok, when Sun is rotating:
"Mass tells space time how to curve and curved space time in turn tells mass how to move".

So, naturally curved space or Gravity field of Sun is also moving.  What  else proof is needed.  Light bending clearly indicates this.

[Kryptid]

What ever you are saying is truth.  But I am talking about future.  In my view, not only Gravity, several other theories will be re-written in future.  It may take lot of time, still I am fully confident that it will be proved that only "one force" exists.

If you are making reference to the unified field theory, that's nothing new. The thing is, that unified field is predicted to only exist at extremely high temperatures. Below that critical temperature, it splits into multiple, different forces.

As said by Newton, same medium is present on Earth as well as in space.  It is the density of this medium that matters.

What medium?

[Colin2B]

It is known and proved fact that Sun is rotating on its axis. 

Agreed

Ok, when Sun is rotating:
"Mass tells space time how to curve and curved space time in turn tells mass how to move".

That has nothing to do with the sun rotating

So, naturally curved space or Gravity field of Sun is also moving.  What  else proof is needed.  Light bending clearly indicates this.

You are misrepresenting the equivalence principle and Newton.
Provide proof that the gravitational field of the sun is moving and this is responsible for light bending, or we will lock this topic.

[Zer0]

false-equivalence-race-hounds.png (54.27 kB . 300x300 - viewed 5636 times)


P.S. - In terms of Favouritism, 1 & 2 are Equal...
But that Does Not mean they are absolutely the Same.
✌️
(Equivalence)

[pasala (OP)]

It is known and proved fact that Sun is rotating on its axis. 

Agreed

Ok, when Sun is rotating:
"Mass tells space time how to curve and curved space time in turn tells mass how to move".

That has nothing to do with the sun rotating

So, naturally curved space or Gravity field of Sun is also moving.  What  else proof is needed.  Light bending clearly indicates this.

You are misrepresenting the equivalence principle and Newton.
Provide proof that the gravitational field of the sun is moving and this is responsible for light bending, or we will lock this topic.

See, I had presented mine hypothesis.  For that present theories on Gravity, Inverse square law or curved space time, are also hypothesis only.  Of course, it is not good to compare with those theories, but I had presented mine idea. 

For that:
01  It is true that as long as the elevator is on the ground, light beam moves out from one hole to the other in the opposite direction.
02  Unless there is a change, up or down, there is no change or something is changing and it is scientifically proved only.
03   If the elevator accelerates forward, light beam bends according to acceleration.

Further ;  "mass tells space time how to curve and curved space tells mass how to move".

Based on this information that:
It is only when the elevator accelerates forward that light beam is moving down.  It is true that,
basing on these information that Einstein predicted bending of light by Gravity.  So as per the above information I had predicted that Gravity is moving down within the elevator and bending light.  Further it is also clear that it is only when the elevator accelerates, clearly indicates that unless Gravity field changes or moves there is no change in the movement of light.

In fact, as per Einstein, mass of the Sun tells space time how to curve and in turn this curved space time once again tells mass how to move. 

I had written above hypothesis based on Einstein thought experiments only.  Those information is collected from the books only.

Once again, I reiterate that I never misrepresented the facts.  It is hypothesis only based on other theories, practically, for me it is impossible to prove it.

Ok, if you are not satisfied, you can take any action as you like.

Thanking you,

Yours
Psreddy

 

[pasala (OP)]

false-equivalence-race-hounds.png (54.27 kB . 300x300 - viewed 5636 times)


P.S. - In terms of Favouritism, 1 & 2 are Equal...
But that Does Not mean they are absolutely the Same.
✌️
(Equivalence)

What ever it may, thanks for comparing with Great man.  I am after all a drop of water. 

[Colin2B]

01  It is true that as long as the elevator is on the ground, light beam moves out from one hole to the other in the opposite direction.

Not so. If the elevator is on the ground it is in a gravitational field and light will bend.

02  Unless there is a change, up or down, there is no change or something is changing and it is scientifically proved only.

No, there doesn’t need to be a change, just a static gravitational field.

Based on this information that:
It is only when the elevator accelerates forward that light beam is moving down.  It is true that,
basing on these information that Einstein predicted bending of light by Gravity.  So as per the above information I had predicted that Gravity is moving down within the elevator and bending light.  Further it is also clear that it is only when the elevator accelerates, clearly indicates that unless Gravity field changes or moves there is no change in the movement of light.

This is a misrepresentation of Einstein’s thought experiment and of actual experiments.

I had written above hypothesis based on Einstein thought experiments only.  Those information is collected from the books only.

Once again, I reiterate that I never misrepresented the facts. 

Yes you have misrepresented, because Einstein never said that in his thought experiments.
Show the pages from the books or this will be locked.

[pasala (OP)]

01  It is true that as long as the elevator is on the ground, light beam moves out from one hole to the other in the opposite direction.

Not so. If the elevator is on the ground it is in a gravitational field and light will bend.

02  Unless there is a change, up or down, there is no change or something is changing and it is scientifically proved only.

No, there doesn’t need to be a change, just a static gravitational field.

Based on this information that:
It is only when the elevator accelerates forward that light beam is moving down.  It is true that,
basing on these information that Einstein predicted bending of light by Gravity.  So as per the above information I had predicted that Gravity is moving down within the elevator and bending light.  Further it is also clear that it is only when the elevator accelerates, clearly indicates that unless Gravity field changes or moves there is no change in the movement of light.

This is a misrepresentation of Einstein’s thought experiment and of actual experiments.

I had written above hypothesis based on Einstein thought experiments only.  Those information is collected from the books only.

Once again, I reiterate that I never misrepresented the facts. 

Yes you have misrepresented, because Einstein never said that in his thought experiments.
Show the pages from the books or this will be locked.

Please go through Forbes, this is why Einstein knew that gravity must bend light:
https://www.forbes.com/sites/startswithabang/2019/04/26/this-is-why-einstein-knew-that-gravity-must-bend-light/?sh=478b1e522ef6

[pasala (OP)]

In fact, as I was studying or gathering information about Gravity, it happened to go by the thinking of great Greek philosophers. 

In their observation:
01   Movement of celestial bodies is not affected by Gravity.
02   Celestial bodies are following nondescending trajectories.
03   Aristotle also opined that these bodies are following natural motion unaffected by external
        force.
04   Some of these philosophers held that a body moving at constant speed requires a
        continuous force acting on it and that force must be applied by contact rather than
        interaction at a distance.

This is the foundation for modern gravitational theory.  Newton argued that the movements of celestial bodies and the free fall of objects on Earth are determined by the same force.

What ever said by Newton is 100% correct and valid.  Gravity  is a force and it is giving you weight on Earth.  Same force is giving movement to the celestial bodies.

In space to measure mass we have to use inertial balance.  If we attach an object to the spring of the inertial balance, the object vibrates and his vibration is measured as mass. What is causing this vibration.  If there is no flow of Gravity, there is no vibrations at all.  Vibrations generated by a Mass is different and it works differently.

Einstein thought experiment, gravity in space ship, in deep space, clearly gives us an idea that gravity is a field present on Earth and it can be packed and moved.  So, it clearly tells us that Gravity is a field  present on Earth like a water pond.  If you go deeper and deeper into the pond, it gives you weight.  If you are on the surface, you are in free fall. 

Suppose, if there is flow of water, rivers, canals, in such case, there is a force of water and even if you are at rest, it forces you to move along with it.   Similarly, gravity field is moving like water in the river, in the space, causing celestial bodies to move. 

As assumed by Newton, same force giving you weight on Earth is moving the celestial bodies.  Here Inverse square law is different, for the present, I am not going deep into that one.

Light coming from distant galaxies is often bent by the presence of massive galaxies (or galaxy clusters) between the distant galaxy and us. This can produce rings, arcs are multiple images.
It clearly tells us, movement of gravity within galaxies.  We have already discussed, unless there is a change in the elevator, up, down there is no light bending at all.  Light taking rings, arcs clearly tells us that there is movement of gravity field.  What else proof is needed.

From this, it is clear that celestial bodies are not moving naturally, inertia of motion.  But it is due  to movement or force of gravity that they are moving or inertia.

Another important point, in my view, yet to be discussed is, why celestial bodies are in non-descending trajectories.  Ok, for better visualization, assume that you are in a river and water is flowing fast, it takes you along with it.  In case for any reason, it slows down, slowly you will start moving down.  It all depends on the density of  the Gravity field in space.  If the density start weakening, slowly, planetary bodies start descending.  If the density weakens further and further, planetary bodies descends further.  Finally, planetary bodies, descends and goes out of control and turns out as asteroids.

  Yours
Psreddy