The(Gravity) of Energy: Mass-Energy Equivalence and Gravitation

Physics, particularly Einstein's theories, have revolutionized our understanding of the universe. The famous equation E mc2 has rewritten our comprehension of mass and energy, suggesting they are fundamentally the same thing. However, this invites a series of questions. If mass and energy are synonymous, does energy have gravity? This blog explores the relationship between mass, energy, and gravity.

Understanding Mass and Energy

Einstein's mass-energy equivalence principle (E mc2) establishes that mass and energy are interchangeable, with energy being equivalent to mass multiplied by the speed of light squared. This profound relation suggests that any form of mass should possess gravitational effects, just like ordinary mass.

In the simplest terms, the universe is composed of radiation and empty space. Radiation (energy) and matter (mass) are two states of the same substance. Radiation is always in motion at the speed of light (c), while matter is a form of condensed radiation. This concept is supported by discussions in various scientific literature.

Properties of Radiation

Radiation consists of two electromagnetic fields, E and H, both perpendicular to each other and the direction of motion. The cross product of these fields forms the Poynting vector S, which is parallel to the direction of radiation propagation. The energy density E and momentum density p, respectively, can be represented as E/S and p S/c2.

Particles, on the other hand, are forms of curl radiation, which are condensed and rotating, giving rise to spin or angular momentum. Despite having no linear momentum (rest mass), particles absorb radiation, gaining momentum and thus moving at various speeds from 0 to c.

The Origin of Gravity

The conservation of momentum, an inherent property of empty space, is the cornerstone of gravity. Just like the law of momentum conservation governs the movement of photons and electrons, it also ensures that momentum is conserved universally. Any attempt to move photon A in one direction requires an equal amount of photon B to move in the opposite direction to maintain the balance.

Quantifying gravity in this context, Bertrand's theorem and Newton's laws of motion help us understand that if the orbit of mass is in a plane and the momentum is conserved, then the forces are of inverse square. This conservation of momentum is the root of gravitational attraction between masses.

The Gravitation of Light and Energy

Light (radiation) and energy don't directly gravitate like mass does. When two light beams cross each other, they do not feel each other's gravitational effects, regardless of the intensity of the beams. The reason is that the conservation of momentum affects the light's direction but not directly its gravitational pull.

However, light beams behave somewhat similarly to mass when it comes to momentum conservation. For instance, in a flashlight, light moves in one direction, but the reaction is transferred to the flashlight itself. The mechanism of gravity becomes evident in the context of circulating radiation and its conservation.

Conclusion

To summarize, energy, as expressed through radiation, does not directly gravitate in the same manner as mass. However, its interactions with other forms of radiation or mass through the conservation of momentum give rise to gravitational effects. Einstein's mass-energy equivalence and the conservation of momentum are the fundamental principles that explain the gravitational phenomenon in the universe.

For a more detailed discussion on the radiation origin of matter, refer to the relevant literature.