Originally Posted by avito009 The logic behind general relativity is more simpler than you think it is. When you throw an object in air vertically the object falls down and the path if you observe is a straight line and there is no force needed in order to travel at constant acceleration which is 9.8 m/s^2 
Why is no force needed?
Newton's laws say that objects accelerate when the net forces on the object are nonzero, so, according to Newton's second law, this 9.8 m/s2 acceleration must require a nonzero net force.
in a straight line. Straight line does not necessarily have to follow an horizontal trajectory it could be vertical.
So no force is needed in gravity so newton was wrong.

No... Newton's laws say that any acceleration requires a nonzero net force. Therefore, when objects accelerate seemingly for no reason (such as an object thrown vertically upwards falling back to the ground), a force must be there. In the case of an object falling to the ground, this force is gravity exerted by the Earth on the thrown object. The object also exerts a gravitational force on the Earth, but this force accelerates the Earth by such a tiny amount that it is not noticeable.
This is a simple reasoning by observing newtons first law which states. An object at rest stays at rest and an object in motion stays in motion with the same speed and in a straight line unless acted upon by an external force. So newton could have reasoned it out as the answer provided by general relativity is present in newtons first law.

What is the "general relativity" result that you are referring to here? Newton's laws are consistent with (special) relativity for the motion of most objects or systems of objects at velocities much lower than the speed of light.
In simple terms the first law states if an object moves in a straight line at constant speed there is no force.

Sure, but just to be pedantic, it's a zero
net force. Constant motion would occur if an object was subjected to two forces of magnitude 10 N and 10N along the same line because the net force would be 0 N.
Now let me explain why newton made this mistake. That is also simple. He observed movement of the Earth and that was due to gravity he reasoned but the Earth did not follow a straight line.
Now came Einstein who reasoned that this path is a geodesic and a geodesic is the shortest distance but it is a geodesic due to curvature of space time. Again this is a mistake made by Einstein as he did not study astrophysics. There is a geodesic but it is due to a reason.

Almost all planetary bodies in the Solar system have orbital paths consistent with Newton's laws. The main exception is Mercury, where relativistic corrections are required for an adequate explanation of its motion.
How is a planet formed? The debris of gas and dust moves and has an initial momentum so when this dust and gas combine to form a planet the same initial momentum is transferred so now the planet has initial momentum some may call it angular momentum. So why does the Earth not move into the sun in a straight line? This is because it is moving and it has initial momentum as explained. So the Earth really wants to move in a straight line but the initial momentum stops it. So the reason given by Einstein that this is a geodesic is correct but this is not due to curvature of spacetime according to me.
So is it correct to say that the earth moves in a geodesic around the sun?

Yes.
Gas and dust clouds are not neat, homogenous spheres with uniform density... they are messy, filled with imhomogeneities and denser pockets. Therefore, when the gas cloud contracts to form a protosystem, it's not going to neatly contract to a tiny point, it's going to be chaotic. There's going to be swirls and twists and blobs of matter moving around in that cloud in a total mess. Inevitably, the result of these complexities is that there will be an axis of rotation established and the cloud settles, over a very long time, to become a spinning disk with a stable axis of rotation. Then, because of gravity, the disk starts to break up into rings and then planets. The kinetic energy of the planets is nonzero because of this process.
You should think of it this way: general relativity is the most correct picture of the motion of objects and Newton's laws are just very, very good approximations for the motion of objects when the velocities of those objects are much lower than the speed of light.
Practically speaking, Newton's laws are usually the start point for motion problems and then relativistic corrections may be required to solve more exotic or complex systems, especially when velocities start approaching the speed of light.