Electro-Magnetic Waves and the Speed of Light

from Google AI:

Does the speed of light emerge from electromagnetic waves? 

Yes. In fact, they are the exact same phenomenon. "Light" is simply the small, visible portion of the broader electromagnetic spectrum. The concept of the "speed of light" essentially describes the speed at which all electromagnetic waves travel through a vacuum. [1, 2, 3] 

This speed naturally "emerges" from the fundamental laws of electricity and magnetism. [1]

How the Speed Emerges

Maxwell's Equations: In the 1860s, physicist James Clerk Maxwell unified electricity and magnetism into a single theoretical framework known as electromagnetism. 

The Wave Equation: When Maxwell combined these laws, the resulting mathematics naturally formed a classic wave equation. This proved that oscillating electric and magnetic fields sustain each other and ripple outward as a self-propagating wave. [1] 

The Mathematical Constant: The equations calculated the precise velocity (\(c\)) of these waves using two fundamental constants of the vacuum: the electric constant (\(\epsilon _{0}\)) and the magnetic constant (\(\mu _{0}\)).The speed is defined by this formula:

\(c = \frac{1}{\sqrt{\epsilon_0 \mu_0}}\) [1, 2, 3]

When you plug the known values for the permittivity and permeability of free space into this equation, it yields precisely \(299,792,458 \text{ m/s}\) (the universally accepted speed of light). [1, 2, 3]

Why it Matters

The term "speed of light" is actually a historical misnomer. It is more accurately described as the speed of electromagnetism. It dictates the speed of all electromagnetic radiation—including radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays—all of which travel at this exact same speed in a vacuum. [1, 2, 3, 4]

To dive deeper into Maxwell's equations and how electric and magnetic constants define space, you can explore the NASA Science Electromagnetic Spectrum guide.

More Google AI:

The entanglement of magnons (quanta of magnetic spin waves) and excitons (electron-hole pairs) forms magnon-exciton entanglement. This represents a powerful quantum-mechanical linkage between electronic, optical, and magnetic states in materials like magnetic semiconductors or antiferromagnetic Mott insulators. [1, 2, 3, 4]

How it Works 

When a material is hit with electromagnetic (EM) radiation (such as light), it can create a localized exciton. If this happens in a magnetic semiconductor, the creation or recombination of the exciton strongly couples to the local magnetic spins, generating or interacting with magnons. [1, 2, 3] 

If you meant polaritons—hybrid quasiparticles of light (photons) and matter (excitons/magnons)—the EM field acts as the fundamental glue. When the electromagnetic field couples simultaneously to an exciton and a magnon, it results in a tripartite entangled state (Photon-Exciton-Magnon). [1, 2, 3, 4, 5]

Why it Matters 

• Opto-Spintronics: It allows you to use light (lasers, photons) to remotely write, read, or control magnetic qubits and spin states.
• Quantum Networks: Distributing quantum information becomes easier if you can convert the stationary, long-lived spin information (magnons) into optical information (excitons/photons) that can travel long distances. [1, 2, 3] 

Recent research demonstrates that spin-entangled optical transitions can emerge naturally from these combined states, opening new avenues for quantum computing, optoelectronics, and long-range entanglement distribution. You can explore the foundational physics behind these interactions through research detailed in Caltech News or ACS Physical Chemistry Au. [1, 2, 3, 4, 5]

How Does Gravity Relate? 

 More from Google AI

Gravity is not the entanglement of gravitons with electromagnetic excitations (magnons, polaritons, or excitons). [1] 

• The Role of Gravitons: In proposed quantum theories of gravity, gravitons are the hypothetical elementary particles that mediate the gravitational force. They couple to all energy and momentum (mass), but are not specifically composed of—or defined by—electromagnetic quasiparticles. [1, 2, 3] 
• The Role of Entanglement: Quantum entanglement is a correlation between physical states. While gravitons can technically become entangled with photons or other electromagnetic fields (and these phenomena are studied in theoretical astrophysics and early-universe cosmology), this is an interaction between fields. It does not define gravity itself. [1, 2, 3]
• Theories of Entangled Space: The idea that entanglement creates spacetime or gravity is a major area of theoretical physics, specifically rooted in the AdS/CFT correspondence and the ER=EPR conjecture. These models propose that spacetime geometry is a geometric representation of underlying quantum entanglement. However, this involves the fundamental entanglement of quantum information networks, not just specific interactions with magnons or excitons. [1, 2, 3, 4, 5]

In short, while gravity, gravitons, and quantum entanglement interact, gravity itself is a fundamental force of nature rather than a specific byproduct of light-matter quasiparticles.

More Google AI:

Is gravity the entanglement of gravitons with bosons?

Not quite. Gravity is the bending of spacetime caused by mass and energy. If gravity operates on the quantum level, it is theorized to be mediated by gravitons. Entanglement itself isn't what gravity is; rather, gravity can cause entanglement between particles, and studying this phenomenon is a key way physicists attempt to test the quantum nature of gravity. [1, 2, 3, 4, 5]

The Core Concepts 

• Gravitons: Hypothetical, massless, spin-2 bosons. In a future unified theory of quantum gravity, they would act as the fundamental force carriers of gravity—just as photons carry electromagnetism. [1, 2]
• Gravity: Under Albert Einstein's General Relativity, gravity is the geometric curvature of spacetime itself. This concept has to smoothly map to the idea of a graviton on a microscopic level. [1, 2, 3, 4]
• Entanglement: A phenomenon where quantum particles remain deeply connected, regardless of the distance between them. [1, 2, 3]

Gravity's Role in Entanglement

Recent research—including tabletop experiments testing Richard Feynman’s long-standing theories—suggests that gravity can actually generate entanglement between two separate massive objects. Because purely classical, non-quantum theories of gravity may be unable to achieve this, detecting this "gravitationally induced entanglement" is seen as a way to prove that gravity has quantum properties, potentially confirming the existence of gravitons.

More Google AI:

Does the difference in speed between mass (slower) and energy (faster) result in gravity being a pure effect of this difference (curved spacetime as energy flows around the mass)

Gravity is not a pure effect of a speed difference between mass and energy. Instead, both mass and energy contribute to the curvature of spacetime. In General Relativity, energy and mass are fundamentally equivalent (E = mc^2), and both serve as the source of gravity. [1, 2, 3, 4]

Why Your Idea is Partially Right (But Incomplete)

• Mass and Energy are Equivalent: In physics, "mass" is essentially highly concentrated, stationary energy. There is no fundamental difference between the two when it comes to gravitational pull. [1, 2]
• Everything Follows the Speed of Light: In relativity, all objects and energy are constantly moving through spacetime at exactly the speed of light (\(c\)). However, how that speed is divided between moving through time and moving through space depends on your speed. Slow-moving objects move mostly through time, while pure energy (like light) moves entirely through space. [1, 2, 3]

The Real Source of Gravity

General Relativity dictates that gravity is a geometric property of spacetime. What actually causes the curvature is not just mass, but the Stress-Energy-Momentum Tensor. This is a mathematical framework representing: [1]

• Mass/Energy Density: How densely packed mass and energy are in a given region.
• Momentum and Pressure: The flow and stress of that energy/momentum. [1]

Mass curves spacetime because it contains energy. When energy or matter moves through the universe, it follows the geodesic curves of this bent spacetime, which we observe as gravity.

More Google AI:

In physics, is mass just another name for momentum?

No, mass is not another name for momentum. They are two distinct but deeply related concepts in physics.

Key Differences

• Mass (m) is an intrinsic property of an object that measures its resistance to acceleration (inertia) and its gravitational pull. It remains the same whether the object is moving or standing still.
• Momentum (p) is a measure of an object's motion. It depends entirely on both its mass and how fast it is moving. If an object is not moving, its momentum is exactly zero, but its mass remains unchanged.

How They Connect

In everyday (classical) physics, the relationship is straightforward:

Momentum = Mass x Velocity

In Einstein's special relativity, the connection becomes more profound. Energy (E), momentum (p), and rest mass (m0) are tied together by the energy-momentum relation:

E^2 = (pc)^2 + (m0}c^2)^2

The Special Case of Light

Light (photons) proves that mass and momentum are not the same thing. A photon has zero rest mass, yet it still carries momentum because it possesses energy. 

More from Google AI:

In physics, is mass just another name for inertia?

Yes, in classical physics, inertial mass is exactly the measure of an object's inertia. However, physics distinguishes between two types of mass that happen to have the exact same value. [1, 2, 3]

The Two Definitions of Mass

Inertial Mass: This is an object's resistance to being accelerated by a force (inertia). It is the "m" in Newton's famous equation:

Force = Mass x Acceleration (F=ma)

Gravitational Mass: This is an object's ability to attract other matter via gravity, and how strongly it responds to a gravitational field. [1, 2, 3, 4, 5]

The Equivalence Principle

For centuries, physicists wondered why an object's resistance to motion (inertia) should perfectly match its weight (gravitational pull). Albert Einstein realized this wasn't a coincidence. [1, 2]

He established the Equivalence Principle, which states that inertial mass and gravitational mass are fundamentally the same thing. This realization became the foundation for his General Theory of Relativity. [1, 2, 3, 4]