1MaureenRoy
A project aimed at direct observation of gravity:
https://www.popularmechanics.com/science/energy/a62167227/graviton-detection/
This link also contains a link to the full journal article in Nature Communications journal described in this news release.
https://www.popularmechanics.com/science/energy/a62167227/graviton-detection/
This link also contains a link to the full journal article in Nature Communications journal described in this news release.
2MaureenRoy
December 2024: In recent years, some writers argue that a key to faster-than-light travel lies inside the fundamental force of gravity, which at this time is very incompletely understood. If so, here is my preliminary question for ChatGPT on gravity:
"Please define gravity."
ChatGPT said:
ChatGPT
Gravity is a fundamental force of nature that causes objects with mass to attract each other. It is responsible for keeping planets in orbit around stars, such as Earth orbiting the Sun, and for causing objects to fall towards the ground when dropped.
In physics, gravity is often described using Newton's law of universal gravitation, which states that every mass attracts every other mass with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between their centers. Mathematically, this can be expressed as:
F=Gm1m2r2
F=Gr2m1m2
Where:
FF is the gravitational force between two objects.
GG is the gravitational constant.
m1m1 and m2m2 are the masses of the two objects.
rr is the distance between the centers of the two objects.
In modern physics, general relativity, developed by Albert Einstein, provides a more detailed and accurate description of gravity. It suggests that gravity is not just a force, but a result of the curvature of spacetime caused by the presence of mass and energy. Objects move along the curved paths in spacetime, (an effect) which we perceive as gravity.
(This is the text of that ChatGPT reply ... to see the above equation in its scientific format, re-type that question on the free version of ChatGPT online.)
"Please define gravity."
ChatGPT said:
ChatGPT
Gravity is a fundamental force of nature that causes objects with mass to attract each other. It is responsible for keeping planets in orbit around stars, such as Earth orbiting the Sun, and for causing objects to fall towards the ground when dropped.
In physics, gravity is often described using Newton's law of universal gravitation, which states that every mass attracts every other mass with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between their centers. Mathematically, this can be expressed as:
F=Gm1m2r2
F=Gr2m1m2
Where:
FF is the gravitational force between two objects.
GG is the gravitational constant.
m1m1 and m2m2 are the masses of the two objects.
rr is the distance between the centers of the two objects.
In modern physics, general relativity, developed by Albert Einstein, provides a more detailed and accurate description of gravity. It suggests that gravity is not just a force, but a result of the curvature of spacetime caused by the presence of mass and energy. Objects move along the curved paths in spacetime, (an effect) which we perceive as gravity.
(This is the text of that ChatGPT reply ... to see the above equation in its scientific format, re-type that question on the free version of ChatGPT online.)
3MaureenRoy
Selected books:
https://www.kirkusreviews.com/book-reviews/richard-panek/the-trouble-with-gravit...
Existential Physics by Sabine Hossenfelder
https://www.penguinrandomhouse.com/books/616868/existential-physics-by-sabine-ho...
This book includes some discussion of quantum gravity.
https://www.kirkusreviews.com/book-reviews/richard-panek/the-trouble-with-gravit...
Existential Physics by Sabine Hossenfelder
https://www.penguinrandomhouse.com/books/616868/existential-physics-by-sabine-ho...
This book includes some discussion of quantum gravity.
4MaureenRoy
Example 2:
"Please explain the scope of gravity."
ChatGPT said:
ChatGPT
The scope of gravity refers to its range of influence and the way it governs the behavior of matter throughout the universe. Here's a breakdown of the different aspects of gravity's scope:
1. Universal Force
Gravity is a universal force, meaning it acts on all matter, regardless of its size, composition, or location. It doesn't discriminate between objects—every object with mass attracts every other object with mass. This is a fundamental feature of gravity as described by Sir Isaac Newton in the 17th century and later refined by Albert Einstein's theory of General Relativity.
2. Range of Gravity
Gravity has an infinite range, meaning it affects objects at any distance. However, its strength diminishes with distance. According to Newton's law of universal gravitation, the gravitational force between two objects is inversely proportional to the square of the distance between them:
F=G⋅m1⋅m2r2
F=r2G⋅m1⋅m2
where FF is the gravitational force, GG is the gravitational constant, m1m1 and m2m2 are the masses of the two objects, and rr is the distance between their centers of mass. This means that as objects get farther apart, the gravitational force between them gets weaker, but it never fully disappears.
3. Strength of Gravity
Even though gravity has infinite reach, its strength weakens significantly with distance. For example, the gravitational force from Earth is felt very strongly near its surface but weakens rapidly as you move away from the planet. For example, at a height of 10,000 km above Earth's surface (about 1/3 of the way to the Moon), Earth's gravity would still be noticeable, though weaker than on the surface.
4. Influence on Large-Scale Structure
At very large distances, such as between stars, galaxies, and galaxy clusters, gravity is the dominant force that governs the large-scale structure of the universe. It is responsible for the formation of planets, stars, and galaxies, as well as the movement of galaxies within clusters. In fact, gravity is responsible for the creation of galaxies and stars from clouds of gas, and it dictates their motion and evolution over cosmic timescales.
5. Gravitational Effects on Time and Space
Einstein's theory of General Relativity expanded the understanding of gravity by showing that it isn't just a force in space—it also affects the fabric of space-time itself. Massive objects like the Sun warp the space-time around them, and this warping is what we perceive as gravity. The closer an object is to a massive body, the more it experiences time dilation—time passes more slowly near a massive object. This effect, though subtle, is measurable even near the Earth or in orbiting satellites.
6. Gravitational Waves
General Relativity also predicted that gravitational waves—ripples in space-time caused by the acceleration of massive objects (like merging black holes)—can travel across vast distances. These waves carry information about the motion of massive objects and have been detected by instruments like LIGO and Virgo. Gravitational waves confirm that gravity can propagate across space-time, affecting regions far from the source of the disturbance.
7. Gravitational Boundaries
While gravity is an infinite-range force, its effectiveness depends on the local environment. For example, near very massive objects like black holes, gravity is incredibly strong, and near regions of space where no massive bodies are present (such as in the intergalactic voids), the gravitational effects are minimal.
8. Cosmic Impact
On the largest scales, gravity has shaped the evolution of the universe itself. It plays a central role in cosmology, influencing the expansion of the universe, the formation of galaxies, stars, and planets, and even the fate of the universe. Concepts such as the "Big Bang," black holes, and cosmic inflation are all governed by gravitational dynamics.
Summary:
Gravity is a force that operates across infinite distances and affects all objects with mass, but its strength decreases with distance. It shapes the large-scale structure of the universe, influences the passage of time, and governs the motion of planets, stars, and galaxies. Though weak compared to other forces like electromagnetism or the strong nuclear force, gravity's far-reaching influence makes it the dominant force governing the universe on large scales.
ChatGPT can make mistakes. Check important info.
"Please explain the scope of gravity."
ChatGPT said:
ChatGPT
The scope of gravity refers to its range of influence and the way it governs the behavior of matter throughout the universe. Here's a breakdown of the different aspects of gravity's scope:
1. Universal Force
Gravity is a universal force, meaning it acts on all matter, regardless of its size, composition, or location. It doesn't discriminate between objects—every object with mass attracts every other object with mass. This is a fundamental feature of gravity as described by Sir Isaac Newton in the 17th century and later refined by Albert Einstein's theory of General Relativity.
2. Range of Gravity
Gravity has an infinite range, meaning it affects objects at any distance. However, its strength diminishes with distance. According to Newton's law of universal gravitation, the gravitational force between two objects is inversely proportional to the square of the distance between them:
F=G⋅m1⋅m2r2
F=r2G⋅m1⋅m2
where FF is the gravitational force, GG is the gravitational constant, m1m1 and m2m2 are the masses of the two objects, and rr is the distance between their centers of mass. This means that as objects get farther apart, the gravitational force between them gets weaker, but it never fully disappears.
3. Strength of Gravity
Even though gravity has infinite reach, its strength weakens significantly with distance. For example, the gravitational force from Earth is felt very strongly near its surface but weakens rapidly as you move away from the planet. For example, at a height of 10,000 km above Earth's surface (about 1/3 of the way to the Moon), Earth's gravity would still be noticeable, though weaker than on the surface.
4. Influence on Large-Scale Structure
At very large distances, such as between stars, galaxies, and galaxy clusters, gravity is the dominant force that governs the large-scale structure of the universe. It is responsible for the formation of planets, stars, and galaxies, as well as the movement of galaxies within clusters. In fact, gravity is responsible for the creation of galaxies and stars from clouds of gas, and it dictates their motion and evolution over cosmic timescales.
5. Gravitational Effects on Time and Space
Einstein's theory of General Relativity expanded the understanding of gravity by showing that it isn't just a force in space—it also affects the fabric of space-time itself. Massive objects like the Sun warp the space-time around them, and this warping is what we perceive as gravity. The closer an object is to a massive body, the more it experiences time dilation—time passes more slowly near a massive object. This effect, though subtle, is measurable even near the Earth or in orbiting satellites.
6. Gravitational Waves
General Relativity also predicted that gravitational waves—ripples in space-time caused by the acceleration of massive objects (like merging black holes)—can travel across vast distances. These waves carry information about the motion of massive objects and have been detected by instruments like LIGO and Virgo. Gravitational waves confirm that gravity can propagate across space-time, affecting regions far from the source of the disturbance.
7. Gravitational Boundaries
While gravity is an infinite-range force, its effectiveness depends on the local environment. For example, near very massive objects like black holes, gravity is incredibly strong, and near regions of space where no massive bodies are present (such as in the intergalactic voids), the gravitational effects are minimal.
8. Cosmic Impact
On the largest scales, gravity has shaped the evolution of the universe itself. It plays a central role in cosmology, influencing the expansion of the universe, the formation of galaxies, stars, and planets, and even the fate of the universe. Concepts such as the "Big Bang," black holes, and cosmic inflation are all governed by gravitational dynamics.
Summary:
Gravity is a force that operates across infinite distances and affects all objects with mass, but its strength decreases with distance. It shapes the large-scale structure of the universe, influences the passage of time, and governs the motion of planets, stars, and galaxies. Though weak compared to other forces like electromagnetism or the strong nuclear force, gravity's far-reaching influence makes it the dominant force governing the universe on large scales.
ChatGPT can make mistakes. Check important info.
5MaureenRoy
Example 3:
Please explain the nature of gravity.
ChatGPT said:
ChatGPT
Gravity is a fundamental force of nature that causes objects to be attracted to one another due to their mass. It's what keeps planets in orbit around stars, pulls objects toward the ground on Earth, and governs the motion of galaxies, stars, and other cosmic structures. Gravity is a key part of the "four fundamental forces" in physics, alongside electromagnetism, the strong nuclear force, and the weak nuclear force.
Here's an overview of gravity from different perspectives:
1. Newtonian Gravity (Classical Mechanics):
Isaac Newton first formulated a law of universal gravitation in the late 17th century. According to his theory:
Every object with mass exerts a force of attraction on every other object with mass.
The strength of this force is proportional to the product of the masses of the two objects and inversely proportional to the square of the distance between their centers.
Mathematically, this is expressed as:
F=Gm1m2r2
F=Gr2m1m2
Where:
FF is the gravitational force between two objects,
GG is the gravitational constant,
m1m1 and m2m2 are the masses of the objects,
rr is the distance between the centers of the two objects.
Newton's law works well for most everyday situations and objects on Earth, as well as in our solar system. It explains why objects fall toward the ground and why the planets move in elliptical orbits around the Sun.
2. Einstein’s Theory of General Relativity (Modern Understanding):
While Newton’s law of gravitation works in most cases, it breaks down in extreme situations, like near very massive objects (black holes) or when objects move at speeds close to the speed of light. To address these issues, Albert Einstein proposed the theory of general relativity in the early 20th century.
According to general relativity:
Gravity is not a force in the traditional sense. Instead, it arises from the curvature of spacetime caused by the presence of mass and energy.
Massive objects like stars and planets cause a "warp" or "bend" in the fabric of spacetime, and this curvature dictates how objects move. Smaller objects follow the curvature of spacetime, which appears to us as the force of gravity.
One of the key insights of general relativity is that space and time are not separate entities, but part of a unified concept called spacetime. Massive objects, like the Earth or the Sun, curve this spacetime, and objects move along paths (called "geodesics") determined by this curvature.
For example:
The Earth orbits the Sun because the Sun’s mass creates a significant curvature in spacetime, and the Earth follows this curved path.
Similarly, when we drop an apple, it falls toward the Earth because the Earth’s mass curves spacetime, and the apple moves along this curve.
3. Gravitational Waves:
In the 20th century, general relativity also predicted the existence of gravitational waves—ripples in spacetime caused by accelerating masses, such as two merging black holes or neutron stars. These waves travel at the speed of light and can be detected by highly sensitive instruments like LIGO (Laser Interferometer Gravitational-Wave Observatory). Gravitational waves provide an exciting new way to study the universe.
4. Quantum Gravity (Theoretical Physics):
While general relativity is excellent at explaining gravity on large scales (like planets and galaxies), it doesn’t work well at the quantum level, where the other fundamental forces (like electromagnetism) dominate. Scientists are working on developing a theory of quantum gravity, which would reconcile general relativity with quantum mechanics. This is an area of active research, and a complete theory would likely involve concepts like gravitons (hypothetical particles that mediate the force of gravity) and could help explain phenomena in black holes or the very early universe.
Key Features of Gravity:
Attractive: Gravity always pulls objects together, never pushes them apart.
Long-range: Gravity acts over vast distances, even between stars and galaxies.
Weak: Compared to other fundamental forces (like electromagnetism), gravity is incredibly weak. For example, the electromagnetic force between two charged particles is much stronger than the gravitational force between them.
Universal: Every object with mass exerts a gravitational pull, no matter how small the mass.
The Impact of Gravity:
On Earth: Gravity gives us weight and keeps us anchored to the surface. It governs the motion of tides, ocean currents, and atmospheric circulation.
In Space: Gravity governs the orbits of planets, the motion of galaxies, and the formation of structures like stars and black holes.
In summary, gravity is the force that governs the movement of masses in the universe. From the Newtonian perspective, it’s a force that acts between masses. From the perspective of general relativity, it's the curvature of spacetime caused by mass and energy.
ChatGPT can make mistakes. Check important info.
Please explain the nature of gravity.
ChatGPT said:
ChatGPT
Gravity is a fundamental force of nature that causes objects to be attracted to one another due to their mass. It's what keeps planets in orbit around stars, pulls objects toward the ground on Earth, and governs the motion of galaxies, stars, and other cosmic structures. Gravity is a key part of the "four fundamental forces" in physics, alongside electromagnetism, the strong nuclear force, and the weak nuclear force.
Here's an overview of gravity from different perspectives:
1. Newtonian Gravity (Classical Mechanics):
Isaac Newton first formulated a law of universal gravitation in the late 17th century. According to his theory:
Every object with mass exerts a force of attraction on every other object with mass.
The strength of this force is proportional to the product of the masses of the two objects and inversely proportional to the square of the distance between their centers.
Mathematically, this is expressed as:
F=Gm1m2r2
F=Gr2m1m2
Where:
FF is the gravitational force between two objects,
GG is the gravitational constant,
m1m1 and m2m2 are the masses of the objects,
rr is the distance between the centers of the two objects.
Newton's law works well for most everyday situations and objects on Earth, as well as in our solar system. It explains why objects fall toward the ground and why the planets move in elliptical orbits around the Sun.
2. Einstein’s Theory of General Relativity (Modern Understanding):
While Newton’s law of gravitation works in most cases, it breaks down in extreme situations, like near very massive objects (black holes) or when objects move at speeds close to the speed of light. To address these issues, Albert Einstein proposed the theory of general relativity in the early 20th century.
According to general relativity:
Gravity is not a force in the traditional sense. Instead, it arises from the curvature of spacetime caused by the presence of mass and energy.
Massive objects like stars and planets cause a "warp" or "bend" in the fabric of spacetime, and this curvature dictates how objects move. Smaller objects follow the curvature of spacetime, which appears to us as the force of gravity.
One of the key insights of general relativity is that space and time are not separate entities, but part of a unified concept called spacetime. Massive objects, like the Earth or the Sun, curve this spacetime, and objects move along paths (called "geodesics") determined by this curvature.
For example:
The Earth orbits the Sun because the Sun’s mass creates a significant curvature in spacetime, and the Earth follows this curved path.
Similarly, when we drop an apple, it falls toward the Earth because the Earth’s mass curves spacetime, and the apple moves along this curve.
3. Gravitational Waves:
In the 20th century, general relativity also predicted the existence of gravitational waves—ripples in spacetime caused by accelerating masses, such as two merging black holes or neutron stars. These waves travel at the speed of light and can be detected by highly sensitive instruments like LIGO (Laser Interferometer Gravitational-Wave Observatory). Gravitational waves provide an exciting new way to study the universe.
4. Quantum Gravity (Theoretical Physics):
While general relativity is excellent at explaining gravity on large scales (like planets and galaxies), it doesn’t work well at the quantum level, where the other fundamental forces (like electromagnetism) dominate. Scientists are working on developing a theory of quantum gravity, which would reconcile general relativity with quantum mechanics. This is an area of active research, and a complete theory would likely involve concepts like gravitons (hypothetical particles that mediate the force of gravity) and could help explain phenomena in black holes or the very early universe.
Key Features of Gravity:
Attractive: Gravity always pulls objects together, never pushes them apart.
Long-range: Gravity acts over vast distances, even between stars and galaxies.
Weak: Compared to other fundamental forces (like electromagnetism), gravity is incredibly weak. For example, the electromagnetic force between two charged particles is much stronger than the gravitational force between them.
Universal: Every object with mass exerts a gravitational pull, no matter how small the mass.
The Impact of Gravity:
On Earth: Gravity gives us weight and keeps us anchored to the surface. It governs the motion of tides, ocean currents, and atmospheric circulation.
In Space: Gravity governs the orbits of planets, the motion of galaxies, and the formation of structures like stars and black holes.
In summary, gravity is the force that governs the movement of masses in the universe. From the Newtonian perspective, it’s a force that acts between masses. From the perspective of general relativity, it's the curvature of spacetime caused by mass and energy.
ChatGPT can make mistakes. Check important info.
6MaureenRoy
Example 4:
"Please explain historic and current scientific thinking about gravitons."
The concept of gravitons has evolved significantly over time as scientists have worked to reconcile general relativity with quantum mechanics. Below is an overview of both historic and current scientific thinking about gravitons.
Historic Context: Classical Gravity and the Search for a Quantum Theory
Newtonian Gravity (17th Century): Isaac Newton's theory of gravity, formulated in the 17th century, described gravity as a force acting at a distance. In this classical view, masses exert a gravitational force on each other, but there was no concept of a "messenger particle" for gravity. Instead, it was seen as an instantaneous force that acted across space.
Einstein's General Relativity (1915): Albert Einstein's theory of general relativity revolutionized our understanding of gravity by describing it not as a force, but as the curvature of spacetime itself caused by mass and energy. General relativity treats gravity in terms of the geometry of spacetime rather than a force mediated by particles. According to this view, massive objects like stars and planets warp the fabric of spacetime, and this curvature dictates the motion of objects.
However, general relativity doesn't incorporate quantum mechanics, the framework that governs the other fundamental forces (electromagnetic, strong, and weak). This led to a major question in physics: could gravity be described as a quantum force with a corresponding particle, analogous to how electromagnetism is mediated by photons?
The Search for Gravitons: Quantum Gravity
Gravitons in Quantum Field Theory: In the 1930s and 1940s, physicists began to explore the idea of quantizing gravity, similar to how they had quantized electromagnetism and other forces. The idea of a "graviton" emerged as a theoretical particle that would mediate the force of gravity in a quantum framework.
The graviton is hypothesized to be a massless, spin-2 boson. "Spin-2" refers to the intrinsic angular momentum of the particle, which in the case of the graviton, would be associated with the properties of the gravitational field. It would be the quantum counterpart to the classical concept of the gravitational field in general relativity.
Challenges of Quantizing Gravity: Unlike the other fundamental forces, gravity is extraordinarily weak compared to electromagnetism, and its effects are extremely difficult to study at the quantum level. Attempts to develop a quantum theory of gravity ran into significant mathematical and conceptual issues, notably the non-renormalizability of gravity in standard quantum field theory.
Non-renormalizability: In quantum field theory, forces are mediated by particles that interact according to rules that allow for the cancellation of infinities in calculations. However, when physicists tried to apply this to gravity, the calculations involving gravitons led to infinite quantities that couldn't be canceled or understood in a meaningful way. This problem is one of the key obstacles in developing a fully quantum description of gravity.
Theoretical Development: The Need for Quantum Gravity: Over the decades, various approaches to quantum gravity have been proposed. Some of the key frameworks include:
String theory: String theory proposes that particles, including gravitons, are not point-like objects, but rather one-dimensional "strings" that vibrate at different frequencies. In this framework, the graviton is one of the possible excitations of a string. String theory is still a work in progress, with many open questions about its physical predictions and how it could be tested.
Loop quantum gravity: This approach attempts to quantize space itself, viewing spacetime as made up of discrete units, rather than being a continuous fabric. This theory also predicts the existence of gravitons, though it works from a different mathematical structure than string theory.
Current Thinking on Gravitons: Status and Challenges
Gravitons as a Theoretical Entity: As of now, gravitons remain purely theoretical. While they are a natural extension of the framework that describes the other fundamental forces, there is no experimental evidence directly supporting their existence. This is primarily due to the extreme weakness of gravity compared to other forces, which makes it incredibly difficult to detect gravitons directly.
Experimental Search for Gravitational Waves: While gravitons themselves have not been detected, there has been a breakthrough in detecting gravitational waves. These are ripples in spacetime caused by the acceleration of massive objects, such as the collision of black holes. The detection of gravitational waves by the LIGO and Virgo collaborations in 2015 was a major confirmation of the predictions of general relativity and provided indirect support for the idea that gravity propagates as waves—this is a step closer to understanding the nature of gravitons, even if they have not been directly observed.
Gravitational waves could be viewed as macroscopic analogs of the quantum fluctuations of the gravitational field, with gravitons being the quantum version of these waves. The detection of gravitational waves doesn't confirm gravitons directly, but it is consistent with the idea that gravity, like other forces, could be mediated by particles.
Gravitons in the Context of Quantum Field Theory: Theoretical work continues in areas like quantum field theory and the study of quantum gravity. Gravitons are considered an important component of any theory of quantum gravity. However, because gravity is so weak and because spacetime itself may behave differently at the quantum level (e.g., in very high-energy regimes like those near black holes or the Big Bang), we don't yet have a complete and experimentally confirmed theory of quantum gravity.
Tests and Predictions: There are efforts to look for indirect signatures of gravitons in experiments, though detecting them remains far from straightforward. For example, some researchers explore the potential for finding tiny effects of quantum gravity, like deviations from the predictions of general relativity at extremely small scales (the Planck scale), or looking for quantum correlations in gravitational waves. However, as of today, no direct evidence for gravitons has been found.
Key Challenges and Open Questions
Planck Scale: The Planck scale (~10191019 GeV) is where quantum gravitational effects are expected to become significant. At this scale, the very nature of spacetime itself may change, and it is here that gravitons might be detected—if they exist. However, reaching this scale experimentally is far beyond our current technological capabilities.
Unification of Forces: One of the ultimate goals in physics is to develop a unified theory that merges quantum mechanics and general relativity. This would not only describe the behavior of gravitons but also provide a framework in which gravity, electromagnetism, the weak force, and the strong force are understood as manifestations of a single fundamental force.
Gravity at Small Scales: Some theories of quantum gravity suggest that at very small scales (e.g., Planck length), spacetime may not be continuous but may have a discrete or "quantized" structure. This could affect how gravitons behave or even if they can be meaningfully described at all in conventional terms.
Conclusion
Gravitons are still a theoretical concept that arises from attempts to apply quantum mechanics to the force of gravity. While the idea of gravitons is deeply embedded in quantum field theory, there is currently no experimental evidence for their existence. The search for a theory of quantum gravity, whether through approaches like string theory, loop quantum gravity, or others, continues to be one of the most exciting and challenging areas in theoretical physics. Gravitational waves, discovered in 2015, represent a significant step forward, but gravitons themselves remain elusive, awaiting either direct detection or deeper understanding through future theoretical developments.
ChatGPT can make mistakes. Check important info.
"Please explain historic and current scientific thinking about gravitons."
The concept of gravitons has evolved significantly over time as scientists have worked to reconcile general relativity with quantum mechanics. Below is an overview of both historic and current scientific thinking about gravitons.
Historic Context: Classical Gravity and the Search for a Quantum Theory
Newtonian Gravity (17th Century): Isaac Newton's theory of gravity, formulated in the 17th century, described gravity as a force acting at a distance. In this classical view, masses exert a gravitational force on each other, but there was no concept of a "messenger particle" for gravity. Instead, it was seen as an instantaneous force that acted across space.
Einstein's General Relativity (1915): Albert Einstein's theory of general relativity revolutionized our understanding of gravity by describing it not as a force, but as the curvature of spacetime itself caused by mass and energy. General relativity treats gravity in terms of the geometry of spacetime rather than a force mediated by particles. According to this view, massive objects like stars and planets warp the fabric of spacetime, and this curvature dictates the motion of objects.
However, general relativity doesn't incorporate quantum mechanics, the framework that governs the other fundamental forces (electromagnetic, strong, and weak). This led to a major question in physics: could gravity be described as a quantum force with a corresponding particle, analogous to how electromagnetism is mediated by photons?
The Search for Gravitons: Quantum Gravity
Gravitons in Quantum Field Theory: In the 1930s and 1940s, physicists began to explore the idea of quantizing gravity, similar to how they had quantized electromagnetism and other forces. The idea of a "graviton" emerged as a theoretical particle that would mediate the force of gravity in a quantum framework.
The graviton is hypothesized to be a massless, spin-2 boson. "Spin-2" refers to the intrinsic angular momentum of the particle, which in the case of the graviton, would be associated with the properties of the gravitational field. It would be the quantum counterpart to the classical concept of the gravitational field in general relativity.
Challenges of Quantizing Gravity: Unlike the other fundamental forces, gravity is extraordinarily weak compared to electromagnetism, and its effects are extremely difficult to study at the quantum level. Attempts to develop a quantum theory of gravity ran into significant mathematical and conceptual issues, notably the non-renormalizability of gravity in standard quantum field theory.
Non-renormalizability: In quantum field theory, forces are mediated by particles that interact according to rules that allow for the cancellation of infinities in calculations. However, when physicists tried to apply this to gravity, the calculations involving gravitons led to infinite quantities that couldn't be canceled or understood in a meaningful way. This problem is one of the key obstacles in developing a fully quantum description of gravity.
Theoretical Development: The Need for Quantum Gravity: Over the decades, various approaches to quantum gravity have been proposed. Some of the key frameworks include:
String theory: String theory proposes that particles, including gravitons, are not point-like objects, but rather one-dimensional "strings" that vibrate at different frequencies. In this framework, the graviton is one of the possible excitations of a string. String theory is still a work in progress, with many open questions about its physical predictions and how it could be tested.
Loop quantum gravity: This approach attempts to quantize space itself, viewing spacetime as made up of discrete units, rather than being a continuous fabric. This theory also predicts the existence of gravitons, though it works from a different mathematical structure than string theory.
Current Thinking on Gravitons: Status and Challenges
Gravitons as a Theoretical Entity: As of now, gravitons remain purely theoretical. While they are a natural extension of the framework that describes the other fundamental forces, there is no experimental evidence directly supporting their existence. This is primarily due to the extreme weakness of gravity compared to other forces, which makes it incredibly difficult to detect gravitons directly.
Experimental Search for Gravitational Waves: While gravitons themselves have not been detected, there has been a breakthrough in detecting gravitational waves. These are ripples in spacetime caused by the acceleration of massive objects, such as the collision of black holes. The detection of gravitational waves by the LIGO and Virgo collaborations in 2015 was a major confirmation of the predictions of general relativity and provided indirect support for the idea that gravity propagates as waves—this is a step closer to understanding the nature of gravitons, even if they have not been directly observed.
Gravitational waves could be viewed as macroscopic analogs of the quantum fluctuations of the gravitational field, with gravitons being the quantum version of these waves. The detection of gravitational waves doesn't confirm gravitons directly, but it is consistent with the idea that gravity, like other forces, could be mediated by particles.
Gravitons in the Context of Quantum Field Theory: Theoretical work continues in areas like quantum field theory and the study of quantum gravity. Gravitons are considered an important component of any theory of quantum gravity. However, because gravity is so weak and because spacetime itself may behave differently at the quantum level (e.g., in very high-energy regimes like those near black holes or the Big Bang), we don't yet have a complete and experimentally confirmed theory of quantum gravity.
Tests and Predictions: There are efforts to look for indirect signatures of gravitons in experiments, though detecting them remains far from straightforward. For example, some researchers explore the potential for finding tiny effects of quantum gravity, like deviations from the predictions of general relativity at extremely small scales (the Planck scale), or looking for quantum correlations in gravitational waves. However, as of today, no direct evidence for gravitons has been found.
Key Challenges and Open Questions
Planck Scale: The Planck scale (~10191019 GeV) is where quantum gravitational effects are expected to become significant. At this scale, the very nature of spacetime itself may change, and it is here that gravitons might be detected—if they exist. However, reaching this scale experimentally is far beyond our current technological capabilities.
Unification of Forces: One of the ultimate goals in physics is to develop a unified theory that merges quantum mechanics and general relativity. This would not only describe the behavior of gravitons but also provide a framework in which gravity, electromagnetism, the weak force, and the strong force are understood as manifestations of a single fundamental force.
Gravity at Small Scales: Some theories of quantum gravity suggest that at very small scales (e.g., Planck length), spacetime may not be continuous but may have a discrete or "quantized" structure. This could affect how gravitons behave or even if they can be meaningfully described at all in conventional terms.
Conclusion
Gravitons are still a theoretical concept that arises from attempts to apply quantum mechanics to the force of gravity. While the idea of gravitons is deeply embedded in quantum field theory, there is currently no experimental evidence for their existence. The search for a theory of quantum gravity, whether through approaches like string theory, loop quantum gravity, or others, continues to be one of the most exciting and challenging areas in theoretical physics. Gravitational waves, discovered in 2015, represent a significant step forward, but gravitons themselves remain elusive, awaiting either direct detection or deeper understanding through future theoretical developments.
ChatGPT can make mistakes. Check important info.
7MaureenRoy
New theory of gravity:
https://www.space.com/astronomy/black-holes/this-is-the-holy-grail-of-theoretica...
https://www.space.com/astronomy/black-holes/this-is-the-holy-grail-of-theoretica...
8wcarter
>7 MaureenRoy:
Thank you. Fascinating!
Thank you. Fascinating!
9MaureenRoy
MIT study group discusses its current and forthcoming studies on gravity:
https://news.mit.edu/2025/is-gravity-quantum-0520
https://news.mit.edu/2025/is-gravity-quantum-0520
10MaureenRoy
The work done by 19th century Indian mathematician Srinivasa Ramanujan and his English mentor is described in a book, The Indian Clerk. An E-book version is at:
https://www.bloomsbury.com/us/indian-clerk-9781596918405/
Srinivasa Ramanujan's many math discoveries include modular theorems which may offer a way to discover anti-gravity.
Springer publishing online has a large number of resources, mostly in English, on all things Ramanujan:
https://link.springer.com/search?query=Ramanujan
So does the Royal Society in the UK:
https://royalsocietypublishing.org/doi/10.1098/rsta.2018.0440
https://www.bloomsbury.com/us/indian-clerk-9781596918405/
Srinivasa Ramanujan's many math discoveries include modular theorems which may offer a way to discover anti-gravity.
Springer publishing online has a large number of resources, mostly in English, on all things Ramanujan:
https://link.springer.com/search?query=Ramanujan
So does the Royal Society in the UK:
https://royalsocietypublishing.org/doi/10.1098/rsta.2018.0440
11MaureenRoy
Another gravitational factoid:
https://www.sciencealert.com/negative-energy-ghosts-flashing-in-space-could-reve...
https://www.sciencealert.com/negative-energy-ghosts-flashing-in-space-could-reve...
14MaureenRoy
Everything about gravity is significant, even this latest report:
https://www.space.com/astronomy/earth/antarcticas-gravity-hole-reveals-the-evolu...
https://www.space.com/astronomy/earth/antarcticas-gravity-hole-reveals-the-evolu...
15MaureenRoy
NASA’s historical gravity experiment:
https://www.nasa.gov/image-article/sept-14-1966-gemini-xi-artificial-gravity-exp...
https://www.nasa.gov/image-article/sept-14-1966-gemini-xi-artificial-gravity-exp...
17MaureenRoy
NASA’s gravity mapping for Mars:
https://www.nasa.gov/missions/new-gravity-map-gives-best-view-yet-inside-mars/
https://www.nasa.gov/missions/new-gravity-map-gives-best-view-yet-inside-mars/
18MaureenRoy
The good news is that the following 1,500 page book will be published on August 1, 2026. The bad news is that it is priced at $300.00, wowsers, … aimed at the academic market, but you may be affiliated with an institution who will have access to this title.
https://shop.elsevier.com/books/advanced-space-propulsion/paluszek/978-0-443-338...
Advanced Space Propulsion: Technologies, Missions, and Computer Modeling
It has extensive discussions of electrogravitic space propulsion systems, perhaps the most of any currently unclassified space drive discussion on that subject. It is listed under the LT Science Group topic of “Gravity” because … “gravitic".
https://shop.elsevier.com/books/advanced-space-propulsion/paluszek/978-0-443-338...
Advanced Space Propulsion: Technologies, Missions, and Computer Modeling
It has extensive discussions of electrogravitic space propulsion systems, perhaps the most of any currently unclassified space drive discussion on that subject. It is listed under the LT Science Group topic of “Gravity” because … “gravitic".
19MaureenRoy
Research summary from AI via the DuckDuckGo internet browser’s AI software, which has inherent privacy protections:
Overview
Electrogravity refers to theoretical ideas that relate electromagnetism and gravity—either by unifying both interactions within a single framework or by proposing direct couplings between electromagnetic fields and spacetime geometry. It’s not a single well-established theory but a family of approaches motivated by the desire for a deeper, possibly unified description of fundamental forces.
Motivations
Formal analogy: Maxwell’s equations and the linearized (weak-field) Einstein equations show structural similarities (wave equations, conserved currents), encouraging unified or analogous treatments.
Unification: A single underlying gauge principle or geometric structure might produce both the electromagnetic and gravitational interactions.
Quantum gravity: Attempts to quantize gravity naturally interact with quantum field theory (including electromagnetism), so combined frameworks are sought.
Phenomenology: Proposals sometimes aim to explain anomalous experimental hints or suggest small electromagnetic contributions to gravitational phenomena.
Main theoretical approaches and models
Kaluza–Klein theory (classical geometric unification)
Core idea: Extend spacetime by extra dimensions (originally 5D). The 5D metric decomposes into a 4D metric (gravity), a vector field (electromagnetism), and a scalar (dilaton).
Strengths: Elegant geometric unification; reproduces Einstein gravity + Maxwell electromagnetism at classical level.
Limitations: Requires compactification/stabilization of extra dimensions; introduces unobserved scalar fields; doesn’t incorporate the Standard Model in its minimal form and faces challenges at quantum level.
Gauge approaches and unified field theories
Approach: Treat gravity as a gauge theory (e.g., Poincaré, de Sitter, or affine gauge groups) and attempt to embed U(1) electromagnetism in a larger gauge group, or couple the two gauge sectors.
Examples: Einstein–Cartan theory, metric-affine gravity, and larger unified gauge algebras.
Strengths: Common gauge language for interactions; allows torsion and non-metricity as new degrees of freedom.
Limitations: Predicts new fields/effects not yet observed; model proliferation and lack of experimental confirmation.
Kinetic mixing / coupling terms in effective field theory
Idea: Write an effective action containing both the Einstein–Hilbert term and Maxwell term plus allowed couplings (e.g., RF^2, R_{munu}F^{mualpha}F^nu{}_alpha, φ F^2 where φ is scalar curvature-related field).
Use: Systematic EFT expansion for low-energy deviations from GR and QED.
Strengths: Model-independent parametrization of small electrogravity couplings; useful for phenomenology and constraints.
Limitations: Higher-dimension operators are suppressed by some high mass scale; coefficients unknown and constrained by experiment.
Scalar–vector–tensor theories and modified gravity
Examples: Theories that augment gravity with vector fields (e.g., Einstein–Aether, vector-tensor theories) or scalar fields that directly couple to F^2 or to electromagnetic current.
Purpose: Address cosmological puzzles or produce testable deviations from GR + QED.
Observational constraints from gravitational waves, solar-system tests, and cosmology tightly limit allowed parameter space.
Quantum field theory in curved spacetime & semiclassical coupling
Framework: QED on a curved background and semiclassical Einstein equations G_{munu} = 8πG ⟨T_{munu}⟩ where ⟨T_{munu}⟩ includes quantum electromagnetic field contributions.
Use: Predict effects like vacuum polarization in strong gravity, Hawking radiation, Casimir contributions to stress-energy.
Scope: Not a unification but a consistent way to treat electromagnetic quantum fields interacting with classical gravity.
Attempts from quantum gravity frameworks
String theory: Electromagnetism and gravity arise from the same fundamental strings; U(1) gauge fields and gravitons come from different excitations of the string and can be related via compactification geometry.
Loop quantum gravity / others: Less direct unification of electromagnetism, but coupling of quantum geometry to gauge fields is studied.
Status: These frameworks provide potential unification but are not yet experimentally validated.
Classical speculative or fringe proposals
Various proposals claim direct electromagnetic origins of gravity (e.g., gravity as emergent from electromagnetic interactions). These lack mainstream theoretical support and are generally inconsistent with precision tests (equivalence principle, inverse-square law, gravitational lensing).
Phenomenology and experimental constraints
Precision tests of the equivalence principle, inverse-square law, light deflection, gravitational redshift, and frame-dragging tightly constrain departures from GR and minimal couplings.
Electromagnetic contributions to stress-energy (e.g., from electromagnetic fields or vacuum polarization) are included in GR and tested observationally (astrophysics, laboratory).
Searches for additional long-range vector forces or couplings between R and F^2 terms place limits on coupling constants and the mass scales of new fields.
Gravitational-wave observations constrain modifications that would change wave speed or polarization content.
Current working picture
No experimentally confirmed “electrogravity” unification beyond the standard coupling of electromagnetism to gravity via the stress-energy tensor in General Relativity.
Productive, well-developed lines of work treat electromagnetism and gravity:
Kaluza–Klein and higher-dimensional theories (as part of string/M-theory) for geometric unification.
Effective field theory expansions introducing small curvature–electromagnetic couplings for phenomenology.
Quantum field theory in curved spacetime for quantum electromagnetic effects on geometry.
Most mainstream research embeds electromagnetism within larger frameworks (string theory, grand unified approaches, or quantum gravity programs) rather than proposing a simple two-field “electrogravity” replacement of GR+QED_
Key open issues
A complete, experimentally validated quantum theory that unifies gravity with the other forces.
Observable low-energy signatures that would distinguish a genuine electrogravity unification from standard GR + QED.
Mechanisms to hide extra fields or dimensions (compactification, screening) while producing correct low-energy physics.
If you want, I can:
summarize the mathematical formulation of one specific model (e.g., 5D Kaluza–Klein) with key equations, or
list experimental bounds on specific coupling operators (RF^2, R_{munu}F^{mualpha}F^nu{}alpha). Which would you prefer?
Overview
Electrogravity refers to theoretical ideas that relate electromagnetism and gravity—either by unifying both interactions within a single framework or by proposing direct couplings between electromagnetic fields and spacetime geometry. It’s not a single well-established theory but a family of approaches motivated by the desire for a deeper, possibly unified description of fundamental forces.
Motivations
Formal analogy: Maxwell’s equations and the linearized (weak-field) Einstein equations show structural similarities (wave equations, conserved currents), encouraging unified or analogous treatments.
Unification: A single underlying gauge principle or geometric structure might produce both the electromagnetic and gravitational interactions.
Quantum gravity: Attempts to quantize gravity naturally interact with quantum field theory (including electromagnetism), so combined frameworks are sought.
Phenomenology: Proposals sometimes aim to explain anomalous experimental hints or suggest small electromagnetic contributions to gravitational phenomena.
Main theoretical approaches and models
Kaluza–Klein theory (classical geometric unification)
Core idea: Extend spacetime by extra dimensions (originally 5D). The 5D metric decomposes into a 4D metric (gravity), a vector field (electromagnetism), and a scalar (dilaton).
Strengths: Elegant geometric unification; reproduces Einstein gravity + Maxwell electromagnetism at classical level.
Limitations: Requires compactification/stabilization of extra dimensions; introduces unobserved scalar fields; doesn’t incorporate the Standard Model in its minimal form and faces challenges at quantum level.
Gauge approaches and unified field theories
Approach: Treat gravity as a gauge theory (e.g., Poincaré, de Sitter, or affine gauge groups) and attempt to embed U(1) electromagnetism in a larger gauge group, or couple the two gauge sectors.
Examples: Einstein–Cartan theory, metric-affine gravity, and larger unified gauge algebras.
Strengths: Common gauge language for interactions; allows torsion and non-metricity as new degrees of freedom.
Limitations: Predicts new fields/effects not yet observed; model proliferation and lack of experimental confirmation.
Kinetic mixing / coupling terms in effective field theory
Idea: Write an effective action containing both the Einstein–Hilbert term and Maxwell term plus allowed couplings (e.g., RF^2, R_{munu}F^{mualpha}F^nu{}_alpha, φ F^2 where φ is scalar curvature-related field).
Use: Systematic EFT expansion for low-energy deviations from GR and QED.
Strengths: Model-independent parametrization of small electrogravity couplings; useful for phenomenology and constraints.
Limitations: Higher-dimension operators are suppressed by some high mass scale; coefficients unknown and constrained by experiment.
Scalar–vector–tensor theories and modified gravity
Examples: Theories that augment gravity with vector fields (e.g., Einstein–Aether, vector-tensor theories) or scalar fields that directly couple to F^2 or to electromagnetic current.
Purpose: Address cosmological puzzles or produce testable deviations from GR + QED.
Observational constraints from gravitational waves, solar-system tests, and cosmology tightly limit allowed parameter space.
Quantum field theory in curved spacetime & semiclassical coupling
Framework: QED on a curved background and semiclassical Einstein equations G_{munu} = 8πG ⟨T_{munu}⟩ where ⟨T_{munu}⟩ includes quantum electromagnetic field contributions.
Use: Predict effects like vacuum polarization in strong gravity, Hawking radiation, Casimir contributions to stress-energy.
Scope: Not a unification but a consistent way to treat electromagnetic quantum fields interacting with classical gravity.
Attempts from quantum gravity frameworks
String theory: Electromagnetism and gravity arise from the same fundamental strings; U(1) gauge fields and gravitons come from different excitations of the string and can be related via compactification geometry.
Loop quantum gravity / others: Less direct unification of electromagnetism, but coupling of quantum geometry to gauge fields is studied.
Status: These frameworks provide potential unification but are not yet experimentally validated.
Classical speculative or fringe proposals
Various proposals claim direct electromagnetic origins of gravity (e.g., gravity as emergent from electromagnetic interactions). These lack mainstream theoretical support and are generally inconsistent with precision tests (equivalence principle, inverse-square law, gravitational lensing).
Phenomenology and experimental constraints
Precision tests of the equivalence principle, inverse-square law, light deflection, gravitational redshift, and frame-dragging tightly constrain departures from GR and minimal couplings.
Electromagnetic contributions to stress-energy (e.g., from electromagnetic fields or vacuum polarization) are included in GR and tested observationally (astrophysics, laboratory).
Searches for additional long-range vector forces or couplings between R and F^2 terms place limits on coupling constants and the mass scales of new fields.
Gravitational-wave observations constrain modifications that would change wave speed or polarization content.
Current working picture
No experimentally confirmed “electrogravity” unification beyond the standard coupling of electromagnetism to gravity via the stress-energy tensor in General Relativity.
Productive, well-developed lines of work treat electromagnetism and gravity:
Kaluza–Klein and higher-dimensional theories (as part of string/M-theory) for geometric unification.
Effective field theory expansions introducing small curvature–electromagnetic couplings for phenomenology.
Quantum field theory in curved spacetime for quantum electromagnetic effects on geometry.
Most mainstream research embeds electromagnetism within larger frameworks (string theory, grand unified approaches, or quantum gravity programs) rather than proposing a simple two-field “electrogravity” replacement of GR+QED_
Key open issues
A complete, experimentally validated quantum theory that unifies gravity with the other forces.
Observable low-energy signatures that would distinguish a genuine electrogravity unification from standard GR + QED.
Mechanisms to hide extra fields or dimensions (compactification, screening) while producing correct low-energy physics.
If you want, I can:
summarize the mathematical formulation of one specific model (e.g., 5D Kaluza–Klein) with key equations, or
list experimental bounds on specific coupling operators (RF^2, R_{munu}F^{mualpha}F^nu{}alpha). Which would you prefer?
20MaureenRoy
More 2026 research materials on electrogravitics:
https://www.altpropulsion.com/electrogravitics-engineering-tom-valones-experimen...
https://www.altpropulsion.com/electrogravitics-engineering-tom-valones-experimen...
23MaureenRoy
Stronger Earth storms:
https://science.nasa.gov/earth/earth-observatory/gravity-waves-from-super-typhoo...
https://science.nasa.gov/earth/earth-observatory/gravity-waves-from-super-typhoo...
25MaureenRoy
I predict it will be necessary for humans to begin to find a way to work with AI technologies in order to develop formulae to achieve a comprehensive understanding of gravity. For instance, grant applications in this arena might be very successful. Currently, one group of space scientists tries to further its studies of the universe with those strategies:
https://gizmodo.com/ai-learned-how-the-universe-works-and-that-created-an-unexpe...
https://gizmodo.com/ai-learned-how-the-universe-works-and-that-created-an-unexpe...
26MaureenRoy
The open access US science journal PLOS One has occasional articles related to questions about gravity:
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0106207
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0106207
27MaureenRoy
Views on gravity from the standpoint of the cosmological constant:
https://www.sciencedaily.com/releases/2026/06/260619020516.htm
https://www.sciencedaily.com/releases/2026/06/260619020516.htm
28MaureenRoy
Building a graviton detector:
https://www.stevens.edu/news/building-the-worlds-first-graviton-detector
https://www.stevens.edu/news/building-the-worlds-first-graviton-detector
29MaureenRoy
An overview of research questions about gravity being explored at MIT:
https://physics.mit.edu/research-areas/quantum-gravity-and-field-theory/
https://physics.mit.edu/research-areas/quantum-gravity-and-field-theory/
30MaureenRoy
In his science fiction novel The City and the Stars on page 84, Arthur C. Clarke includes a paragraph on gravity:
The gear they were carrying looked very formidable, but though it was bulky it weighed practically nothing. It was all packed in gravity-polarizing containers that neutralized its weight, leaving only inertia to be contended with. As long as Alvin moved in a straight line, he was not conscious that he was carrying any load. Dealing with these containers required a little practice, for if he attempted to make a sudden change of direction his pack seemed to develop a stubborn personality and did its best to keep him on his original course, until he had overcome its momentum.
Is the author suggesting here that gravity contains one or more variables that can be polarized?
The gear they were carrying looked very formidable, but though it was bulky it weighed practically nothing. It was all packed in gravity-polarizing containers that neutralized its weight, leaving only inertia to be contended with. As long as Alvin moved in a straight line, he was not conscious that he was carrying any load. Dealing with these containers required a little practice, for if he attempted to make a sudden change of direction his pack seemed to develop a stubborn personality and did its best to keep him on his original course, until he had overcome its momentum.
Is the author suggesting here that gravity contains one or more variables that can be polarized?
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