Gravity is what holds the planets in orbit around the sun and what keeps the moon in orbit around Earth. The gravitational pull of the moon pulls the seas towards it, causing the ocean tides. Gravity not only pulls on mass but also on light. Albert Einstein discovered this principle
Amirali
You speak more about Newton's ideas of gravity.
Einstein's ideas are vastly different. Einstein said that gravity is not a force, therefore it doesn't 'hold' anything and doesn't 'pull' on anything.
He said that gravity is essentially a curvature of four-dimensional space-time.
The upshot is that masses tells space-time how to curve, and space-time tells masses how to move.
The planets and the Moon (and any falling body) move on a geodesic, which is a straight line in curved space-time.
Regards Robert Holmes
I agree with the ideas of Robert Holmes. Two substances exert a force of attraction on one another known as "gravity." Sir Isaac Newton quantified the gravity between two objects when he formulated his three laws of motion. The force tugging between two bodies depends on how massive each one is and how far apart the two lies. Even as the center of the Earth is pulling you toward it (keeping you firmly lodged on the ground), your center of mass is pulling back at the Earth. But the more massive body barely feels the tug from you, while with your much smaller mass you find yourself firmly rooted thanks to that same force. Yet Newton's laws assume that gravity is an innate force of an object that can act over a distance, instantaneously!!!!!!!
In his theory of Special Relativity, Albert Einstein, determined:
1) the laws of physics are the same for all non-accelerating observers,
2) the speed of light within a vacuum is the same no matter the speed at which an observer travels.
As a result, he found that space and time were interlaced into a single continuum known as space-time. Events that occur at the same time for one observer could occur at different times for another. As he worked out the equations for his general theory of relativity, Einstein realized that massive objects caused a distortion in space-time. So, gravity is a "curvature of space" rather than a force.
As a Geophysicist, Gravity plays a fundamental role in the search for favorable structures to trap oil and gas. I attach an interesting AGU's article "Einstein and Geophysics: Valuable Contributions Warrant a Second Look".
Best wishes, Mario E. Sigismondi
You mentioned both, the Newton's approach and also Einstein. They both are in principle right, but Einstein's General Relativity is more precise - explaining some effects that Newton's theory could not explain, e.g. bending of light beams around massive bodies, or observable apsidal precession of the planet Mercury. In practical spaceflights and celestial mechanics in Solar system the Newtonian and Kepler laws are in most cases satisfactory precise.
Amirali,
You appear to have answered your own question - what do you wish to know?
It is not an innate property of the mass. Attracting bodies accelerate towards each other. Consequently, work is being done. The bodies do not waste their energy. The bodies are "pushed" to each other by the external environment of the electromagnetic field. We are convinced of the existence of the field whenever we bring a mobile phone to our ear. I solved Maxwe equations for gravity. The solution is the Newton World Law. Experiments on the modification of the Cavendish experiment. They confirm these findings.
Valeriy,
If I place a mass of lead in a thick-walled copper box I prevent electromagnetic waves from escaping. If I have two of these lead masses-in-copper-boxes, I suggest to you that they will slowly draw together - in the absence of electromagnetic interaction.
Furthermore, if gravitational force is somehow a gradient of electromagnetic fields, why can we not detect these fields directly?
What causes the gravity of different masses like earth ?
The density of energy-momentum (second order energy-momentum tensor) that you have in a certain zone of the space-time.
I have studied in the past some notions:
* The propagator theory of a quantum system, ...
* The Attempt to unify the 4 fundamental interactions, ...
* The gravitational waves, ...
* Etc, ...
Dear Physicists, are there mutual connection?!
What's go, from a first planet to a second and exert a force to attract it? !!!
Sorry, for this ignorant question!
James,
Own vortex electromagnetic field flows around each particle. When particles join their fields go outside the fragment. When you combine copper and lead, you simply increase the flow of the field outside. You cannot measure these flows. Instruments respond to directional flows. And here through each point the streams go in all directions.
Vortex flows of the field wash the Earth. Their density decreases with height (1/r). According to the Bernoulli effect, the total pressure of the field consists of the pressure of the horizontal flows and the radial pressure of the interplanetary medium of the field. We call this area of the presence of a gradient a gravitational field. The body in this field is affected by the radial force from the environment.
Earth does not attract the Moon. The external environment of the field "pushes" the Moon to Earth. Absolutely the same vortex attraction mechanism for galaxies, atoms and particles. Read more in the book "Gravity" in my profile or on the website http://gravity.spb.ru
Dear Noureddine,
Why do you need to have a force going from one planet to the other for understanding their mutual gravitational interaction? What is important for Physics is that you can calculate such interaction in many different conditions.
It is true that when the gravitational potentials are not so big you can get a Newton-Galilean Representation and to reduce the gravitational interaction to have forces due to the gradient of such potentials.That is only one possibility for planets non-relativistic, but we have much more objects interacting gravitationally: neutron stars, black holes, gravitational waves...which needs to take into account the General Relativity of Einstein. This theory generalizes the source of gravitation to the energy-momentum tensor which equals to the curvature of the spacetime. This is very abstract and far of being intuitive but it doesn't matter because the important is that allows to calculate with great accuracy the gravitational behaviour of new objects of the Universe. This is the relevant and no to invent a force travelling from one planet to the other for obtaining their interaction as if we were in a Feynman's diagram !
https://en.wikipedia.org/wiki/Stress%E2%80%93energy_tensor
https://en.wikipedia.org/wiki/General_relativity
I think that it is not necessary to say that in Physics as in every logic system, there are initial (fundamental) concepts that are assumed to be given. The mass, the charge, time, etc ...are possible to be measured but not defined by more basic concepts than them. What is important is that they allow to find laws given by equations which allow to predict and find new phenomena. This is the important and only humble scientific procedure. Asking, for instance, what is a mass could be very appealing but impossible due to be a fundamental concept in Physics.