Gravity : no messenger particle necessary?

Question

Imagine you and a friend are standing on the equator, 90 degrees apart, with you in Kansas and your friend near Hawaii. You both start walking in a straight line, north.

You notice that the further north you go, the closer you and your friend are. Its as if there is a force acting between you two, pulling you two together.

Is there really a need for a force carrying particle (a graviton I think its called) to attract 2 bodies? So why do they think there is one, other than it being a cosmetic issue for the standard model? Same goes for looking for gravity waves.

Answer 1

Most scientists *assume* there's a need for the graviton to propagate the force of gravity because gravity is one of the four fundamental forces and the other three all have 'messenger particles' associated with them. On the other hand, Einstein's relativity showed -- and it's been proven valid -- that what we call the 'force' of gravity is actually a curvature or distortion of spacetime caused by mass. Would that require a 'messenger particle?' I certainly don't know, nor does anyone else because we don't even totally understand what gives mass all of its characteristics. Maybe if/when the search for Higgs boson is successful we'll know.

As for gravity waves, I can't think of any reason they shouldn't exist.

Answer 2

The equator of the earth isn't in Kansas. It's actually thousands of miles south in Ecuador. Kansas is roughly 40 degrees north of the equator.

The fact you and your friend are approaching one another isn't an attractive force. Even though you are traveling along a curved surface nothing is dragging you up, excpet for the force you exert against gravity trying to pull both of you to the center of the earth. Gravity will never do this because it is incredibly weak. The proof is that the electrons in your feet repel the electrons in the ground far more than gravity is attracting you downward. Solid objects can't pass through one another, except in black holes, maybe.

However, you and your friend actually are attracting each other gravitationally, but the force of the attraction is too small to be measured. Only if one (or both) objects are incredibly massive is gravity measurable. Your friend would have to have the mass of long island before you would feel any actual attraction.

There are 5 fundamental physical forces in the universe: electricity, magnetism, the strong and weak nucleur force and of course, gravity. Electricity and magnetism can easily be described in terms of the other force. This also applies to the pair of nucleur forces. All the forces can be described in terms of one another except - you guessed it - gravity. Because of this, nobody knows what happens inside "black holes" or what the universe was like when it began and all the forces were united.

Therefore, until gravity can be explained, scientists are forced to use all kinds of wierd and implausable theories to try and explain a thing which can't be described in terms of anything except itself.

Gravity is the untimate enigma.

Answer 3

It is known that Quantum Mechanics and General Relativity contradict each other: they cannot both be right. Furthermore, it is a drawback of GR that it is a classical theory and cannot describe physics correctly in very small places, such as the center of a black hole and the beginning of the universe. It is a drawback of QM that it is not truly Relativistic, and the parts of it that are give bizarre results that always require you to subtract infinity before arriving at a real answer.

So the assumption really is that both are wrong somehow, and each is the appropriate limit of a single greater theory (the Theory of Everything) that includes them both. Such a theory would likely describe gravity as both a field and a particle, just as the other three forces are described. In this case, it just so happens that the field is a metric one.

Answer 4

First Newton has been interpreted as indicating that force is the cause and alteration of all motion.
Actually it is the Power stored in space which at one time was called the Aether, that causes all motion of mass structures in the Universe.

It is the disturbance of the space structure that causes forces to moves in space and they always exist in pairs.

This disturbance of space Einstein described it as a distortion of the medium of space.

He expressed it as the Curvature of Space as being the expression of the Gravity phenomenon.

General relativity has been accepted and believed to have been proven.

Quantum mechanics is struggling to define forces in nature and have not been able to Unify one mechanism that Unifies all natural phenomna into one common process.
General relativity did that in Einstein Field Equation because it related Gavity in terms of Energy density of space which is in reality the power that is stored in space locked in as space pressure.

The Graviton is defined as mediator of a force which is inherent only in the atom's Nucleus.Nothing is mentioned of a second reactive force which would be in agreement with Newton 3rd Law of motion.
The Graviton postulation in Quantum mechanics just does not seem to agree with General Relativity. Hence it appears to remain just as postulation of Quantum mechanics theories.