Gravitational lensing is a remarkable phenomenon that occurs when the immense gravity of a massive celestial object, such as a galaxy or a cluster of galaxies, bends and distorts the path of light from distant objects behind it. This effect can result in the formation of multiple images, arcs, and even Einstein rings, providing a … Read more
The bending of light, or gravitational lensing, is a phenomenon that reveals crucial information about the nature of space-time. According to Einstein’s theory of general relativity, massive objects like stars and galaxies cause a distortion in space-time, which results in the bending of light as it passes near these objects. This curvature of space-time is … Read more
The concept of a gravitational field being a magnetic field is not supported by current scientific understanding. While both gravity and magnetism are fundamental forces of nature, they have distinct properties and behaviors that make them separate and distinct phenomena.
Understanding Gravity and Magnetism
Gravity is a force that attracts two objects towards each other, regardless of their magnetic properties. It is a universal force that acts on all matter, including those without any magnetic properties. The strength of the gravitational force is directly proportional to the masses of the objects and inversely proportional to the square of the distance between them, as described by Newton’s law of universal gravitation.
On the other hand, magnetism is a force that attracts or repels objects based on their magnetic properties. Magnetic fields are created by the motion of electric charges, and they can either attract or repel other magnetic objects, depending on the orientation of their magnetic poles. Magnetism only affects objects with magnetic properties, such as iron, nickel, or cobalt.
Theoretical Differences
Gravity is described by the theory of general relativity, which was developed by Albert Einstein in the early 20th century. This theory explains gravity as a consequence of the curvature of spacetime, where massive objects distort the fabric of spacetime, and other objects move in response to this distortion.
Magnetism, on the other hand, is described by the theory of electromagnetism, which was developed by James Clerk Maxwell in the 19th century. This theory explains magnetism as a result of the motion of electric charges, and it describes the relationship between electric and magnetic fields.
Quantifiable Differences
The strength of a magnetic field can be measured in units of Tesla (T) or Gauss (G), while the strength of a gravitational field can be measured in units of Newtons per kilogram (N/kg) or acceleration due to gravity (g). These units are fundamentally different and cannot be directly compared, as they represent different physical quantities.
For example, the Earth’s magnetic field varies from approximately 0.25 to 0.65 Gauss, while the acceleration due to gravity on the Earth’s surface is approximately 9.8 m/s².
Theoretical Speculations and Limitations
There have been some speculations that gravity may be a result of a magnetic field, as suggested in some theoretical models. However, there is no concrete evidence to support this claim, and it remains a subject of ongoing research and debate.
Similarly, the idea that magnetism may be a lens focusing or manipulating gravitational force, as suggested in some studies, is also not supported by current scientific understanding. The two fields are fundamentally different and cannot be directly compared or interchanged.
Conclusion
In summary, while both gravity and magnetism are important forces in nature, they are distinct and separate phenomena, described by different theories and characterized by different physical properties and behaviors. There is no evidence to suggest that a gravitational field is a magnetic field, and the two fields cannot be directly compared or interchanged.
After reading this article, you will understand what is the negative gravitational field, is gravitational field negative or not, and some detailed facts.
The region of antigravity, where the objects don’t feel the gravitational pull on them instead they will repel away from each other present in this field then it is a negative gravitational field.
What is Negative Gravitational Field?
The gravitational force is basically a force of attraction between the two objects and acts equal and opposite in magnitude and direction.
Due to some circumstantial forces, the objects will exert a force on the other objects in close vicinity to move them away from the gravitational field; this is known as the negative gravitational field.
The gravitational field region is a space within which the force is experienced on every object present in this field. Due to this, every object is bonded with each other with a tiny force that is not felt on the body but does exist. This gravitation force decreases as the distance from the object constituting its gravitational field increases, as the gravitational force is inversely proportional to the square of the distance among them.
F=G m1m2/r2
Where G=6.67*10-11
m1 is mass of object 1
m2 is mass of object 2
‘r’ is a distance between the two objects
If the object is present in the negative gravitational field, then the objects will repel away from each other. Every object will exert a push force on the other object to push it away from its surrounding region.
The gravitational field is a region showing the force of attraction which is very small between the objects having a mass and is present in this field, and this gravitational force diminishes as the object moves away from another object or from the gravitational field.
The negative gravitational force is a very tiny repulsive force between the objects having masses due to the presence of dark matter.
The gravitational field is defined by the change in the gravitational potential of the field in every orbit around the massive mass which is equal to the negative gradient of the field strength; hence the gravitational field is negative.
The gravitational field strength is given as the force exerted by the object of mass ‘M’ on the object having mass ‘m’ at a distance ‘r’, given by the relation,
g=F/m
The gravitational force is formulated as, F=G mM/r2
When the object is in the negative gravitational field, every object in this negative field will exert a force on every object to push it away from its own gravitational field as shown in the below figure.
Negative Gravitational Field
If the object with mass ‘M’ has a greater gravitational potential field as compared to the object with mass ‘m’ present in the negative gravitational field, then the force applied by the mass ‘M’ will be greater than the object with mass ‘m’. If so is the case, then the object with mass ‘m’ will be displaced away from this massive object as it will repel from its negative gravitational field. The same is shown in the below figure. The object is displaced from its original position to a distance r+dr from the massive object having a mass ‘M’.
The gravitational potential energy is positive. This signifies that this is a repulsive force between the two objects. We knew that the negative sign implies the force of attraction between the two bodies.
This gravitational potential energy is inversely proportional to the distance between the two objects, and hence we can say that the gravitational potential energy will decrease as the distance of separation of two objects increase further and further.
The negative gravitational force decreases with subsequent orbits, and if these objects come in close vicinity of the positive gravitational field, then they will show the force of attraction towards these positive gravitational fields.
The gravitational force always shows a tiny force of attraction, but if the object is in the negative field then the objects will show a force of repulsion.
The gravitational force is negative if the object imposes a force on the other object to repel it away from its field instead of attracting and the potential energy of the field is positive.
The gravitational field becomes negative at an infinite distance where it becomes difficult to impose the force of attraction due to hindrance. The object will repel away from the gravitational field region of a certain massive mass if the potential energy of that object becomes equal to its kinetic energy. If the object gains enough kinetic energy to escape from the gravitational pull of that body, then the object will show repulsion from the massive object.
Does a dark energy is responsible for the negative gravitational field?
Dark energy is a theoretically postulated form of energy that is found in the entire universe and is considered a cause for the expansion of the universe.
The presence of dark energy leads to the opposition of the gravitational force due to it, thus causing an expansion and accelerating the object away from the gravitational field of the massive objects.
How is the gravitational force negative?
The gravitational force is not exerted on the object if it is present at an infinite distance from the gravitational field produced by the massive object.
The magnitude of the gravitational force is F = G m1m2/r2 but in vector form the force due to one mass is reacting in the direction opposite to the force due to another object, that is, F =-G m1m2(r2-r1)3/r2-r1thus denoted as negative.
How can the gravitational force be repulsive?
If the object is at an infinite distance from the source object then the gravitational force will be a minimum due to that object.
At the same sequence if that object falls near the gravitational field region due to another massive object, then it will be attracted towards it and repel away from the gravitational field of another object present at an infinite position.
Does the explosion of supernovas signify negative gravitational force?
The gravitational force always points towards the center of any object having mass.
At the time of the explosion, the force due to gravity is very less compared to the centrifugal force acting outward, thus causing the explosion, and the gravitational field during this time is negative.
Does the work done by the negative gravitational field on the object is negative?
Gravitational field strength is a mechanism for measuring gravity. It shows the magnitude of gravity at a particular place.
Gravitational field strength is a vector quantity consisting of direction as well as magnitude.
Is gravitational field strength a vector ? Yes, it is, as its formula is gravitational force per unit mass. As gravitational field strength consists of force, and as force is a vector quantity, it naturally makes it a vector quantity.
A scalar quantity will only have magnitude, i.e. a number. For example – 25 metres. It is always one-dimensional.
A vector quantity will have magnitude as well as direction. For example – 25 metres, north. It is multi-dimensional.
What is Gravity?
Gravity is expressed as the force of attraction between any two objects in the universe. It is the weakest force in the universe and has no specific range.
The gravitational force is enormous when the object is heavier. Thus, always the lighter object will be attracted towards the heavier object. Due to this reason, the Earth orbits around the sun, and moon around the Earth.
The exciting fact about gravitation is that all the objects in this universe have their own gravitational field, including humans!
Yes! You read it correctly. But, as gravity is the weakest force, all other gravitation fields are negligible compared to the earth’s gravitational force or, in fact, weaker than any other planet’s gravitational force.
For comparing a human’s gravitational field to that of the Earth’s gravitational field, let us take an example. Say, person A is standing one meter away from person B, who weighs 100 Kg. Earth’s gravitational acceleration will be 1.5 billion times larger than the gravitational acceleration of person B. That is why person A will not gravitate to person B.
Another critical subject heavily affected by gravity is mass and weight. Mass is the quantity of matter available in an object, while weight is the outcome of the force of gravity acting on it. Mass multiplied by gravity gives weight.
w = m x g
Where,
w = Weight
g = Gravitational Field Strength or Gravitational Acceleration
m = Mass of the object
Gravity is one of the four elemental forces of nature. Gravity affects the solar system or, in fact, any system in the universe. The formation of stars, planets, asteroids, etc., all depends on gravity.
Various scientists like Robert Hooke, Galileo Galilei, Jesuits Grimaldi, Riccioli, Bullialdus, Borelli, etc., put forward different theories on gravitation, and some of which are very similar to each other but still not entirely practically proven. Ancient Greek Philosophers like Archimedes, Roman architect and engineer – Vitruvius, Indian mathematicians and astronomers like Aryabhatta and Brahmagupta also identified Gravity.
But then, one fine day, an apple fell upon Sir Isaac Newton, and he derived the “Newton’s Law of Universal Gravitation” and the world followed it. According to Newton’s theory, the gravitational force is directly proportional to the product of masses and inversely proportional to the square of the distance between them.
The equation for gravitational force is given as:
Fα(m1m2)/r2
To remove the proportionality sign, a constant is added. In this scenario, it is the gravitational constant “G”.
F=G*(m1m2)/r2
Where,
F = Gravitational Force
G = Gravitational Constant = 6.674 x 10-11 N.m2.kg-2
Gravitational field strength is a physical quantity according to classical mechanics.
Gravitational field strength is denoted by ‘g’, and its formula is given as force per unit mass.
g=F/m
Where,
g = Gravitational Field Strength
F = Gravitational Force
m = Mass of the Object
According to this formula, the S. I. Unit of g is N/Kg, and earth’s gravitational field strength is 10 N/Kg. “g” is also referred to as the Gravitational Acceleration, given as 9.8 m/s2 for earth.
As force is a vector quantity, gravitational force will be a vector quantity, making gravitational field strength a vector quantity.
Albert Einstein also put forward his theory for gravitation in his general theory of relativity, and it also has superseded Newton’s theory. Still, it is only used when there is the requirement for extreme accuracy or when dealing with a powerful gravitational field near a super-massive and extremely dense object like the black hole.
The bending of space-time is a tricky concept, but it is explained in the general theory of relativity given by Albert Einstein. Here, we only need to understand that it involves the 3-dimensional space and 1-dimensional time, and thus, it is a 4-dimensional flow. So, due to gravity, there is a change in the space-time flow, resulting in different perceptions of observations of an event from different places or observers.
Comparison of Gravitational Acceleration on different planets of our Solar System.
Gravitational acceleration is the speed at which the planet pulls a body. For Earth, its value is 9.8 m / s2. Let’s try to find the acceleration due to gravitation on different planets present in our solar system.
One can detect the gravitational acceleration of any planet using the formula:
g=Gm/r2
Where,
g = Gravitational Acceleration
G = Gravitational Constant = 6.674 x 10-11 N. m2. kg-2 (it will be same everywhere)
r = radius of the planet
m = Mass of the Planet
Gravitational acceleration on Mercury
For Mercury,
g = ?
G = 6.674 x 10-11 N. m2. kg-2
r = ~2.4 x 106 m
m = 3.28 x 1023 Kg
Putting all this information in the formula, we get:
g = 3.61 m / s2
Gravitational Acceleration on Venus
For Venus,
g = ?
G = 6.674 x 10-11 N. m2. kg-2
r = ~6.07 x 106 m
m = 4.86 x 1024 Kg
Putting all this information in the formula, we get:
Putting all this information in the formula, we get:
g = 3.75 m / s2
Gravitational Acceleration on Jupiter
For Jupiter,
g = ?
G = 6.674 x 10-11 N. m2. kg-2
r = ~6.98 x 107 m
m = 1.90 x 1027 Kg
Putting all this information in the formula, we get:
g = 26.0 m / s2
Gravitational Acceleration on Saturn
For Saturn,
g = ?
G = 6.674 x 10-11 N. m2. kg-2
r = ~5.82 x 107 m
m = 5.68 x 1026 Kg
Putting all this information in the formula, we get:
g = 11.2 m / s2
Gravitational Acceleration on Uranus
For Uranus,
g = ?
G = 6.674 x 10-11 N. m2. kg-2
r = ~2.35 x 107 m
m = 8.68 x 1025 Kg
Putting all this information in the formula, we get:
g = 10.5 m / s2
Gravitational Acceleration on Neptune
For Neptune,
g = ?
G = 6.674 x 10-11 N. m2. kg-2
r = ~ 2.27 x 107 m
m = 1.03 x 1026 Kg
Putting all this information in the formula, we get:
g = 13.3 m / s2
Gravitational Constant vs. Acceleration Gravity
There are innumerable and remarkable differences between the gravitational constant and acceleration gravity. It would be easy to study them in the tabular format.
Also known as “Newtonian Constant of Gravitation” or “Universal Gravitational Constant” or “Cavendish Gravitational Constant.”
Also known as “Gravitational Field Strength”.
Denoted by “G”.
Denoted by “g”.
The value of the gravitational constant is independent of all factors, and thus, remains the same throughout the universe.
The value of acceleration gravity is different on different planets or any other astronomical object.
It is proportionality constant, and thus, it would remain the same anywhere, be it the centre of a planet, outside of it, near the poles, in vacuum, etc., the value of G will remain as it is, without any change.
The gravitational acceleration is maximum at the earth’s surface. Gravitational acceleration starts decreasing whether one moves in upward or downward direction.
Gravitational constant is a scalar quantity.
Acceleration gravitation is a vector quantity.
Value of gravitational constant is never zero.
Value of acceleration gravitation is zero at the centre of the earth.
No formula for G.
Formula for finding g = F/m
The relation between G and g can be given as: G=gr2/m G =
The relation between G and g can be given as: g = GM/r2
S. I. Unit of G = N. m2 / kg2
S. I. Unit of g = m / s2
G = 6.674 x 10-11 N. m2. kg-2
Value of gravitational acceleration for earth = g = 9.8 m / s2
