How Light Travels Through Space Without Losing Energy
Light, composed of massless photons, is an fascinating aspect of our universe. While some scientific theories suggest that light might lose energy as it travels through space, modern physics argues the opposite. This article delves into the principles behind the conservation of energy and how photons behave as they traverse vast distances in the cosmos.
Understanding Photons and Energy Conservation
The crux of the issue lies in the nature of photons. These particles, which are massless excitations of the electromagnetic (EM) field, do not lose energy because they are not made up of something else that can be radiated away. Instead, they interact with oscillating electric fields of atoms that are remote from the atom that generated them. These interactions are the foundation of optics.
When a photon is absorbed by these oscillating electric fields, the energy is transferred to boost the field's oscillations. This makes the field unstable relative to its surrounding conditions and it eventually emits one or more photons. While the total amount of energy remains constant, the energy of the emitted photons is often lower than the absorbed photon's energy. This is due to the incremental nature of these interactions—one quantum of energy at a time. Thus, while the aggregate energy is not lost, the intensity might appear to diminish.
No Loss in Vacuum Conditions
In the absence of matter or atoms—such as in the vacuum—photons travel unchanged in energy level. The EM field in the vacuum does not interact with these massless particles, allowing them to continue propagating without losing energy. This principle is a cornerstone of the conservation of energy law, which states that energy cannot be created or destroyed, only transformed from one form to another.
Interactions with Gravitational Fields
Photons also interact with gravitational fields, leading to changes in their paths. However, this interaction does not result in a loss of energy. Instead, a photon's path is deflected, causing it to follow a parabolic trajectory, centered around the gravitational source. Consequently, the photon's energy remains constant; it is redirected rather than diminished.
Dissipation and Space-Time
Another unique characteristic of light is its helicity, or the lateral wave component. As light expands spherically from a point source, it dissipates because the effective helical 'circumference' of the wave expands. This expansion causes the energy to spread out, leading to a perceived decrease in intensity.
Furthermore, light interacts with other particles in space, such as free fermions (e.g., electron-positron pairs). These particles absorb the light and re-emit it, but not in a uniform manner. Each particle re-emits the light in its own local rest frame, which is the only frame it perceives. This localized re-emission contributes to the overall conservation of energy across the universe.
The concept that space itself is an infinitely bounded, finite space in relative motion is a revolutionary idea proposed by physicist Albert Einstein in his 1952 paper. This understanding is crucial for comprehending the behavior of light and particles in the expanding universe. Future advancements in technology, particularly in the use of massive dishes or arrays, will be necessary to detect the lateral motions that occur in these bounded spaces.