Why Ancient Photons Travel Immense Distances While Flashlights Struggle
It may seem a paradox that a single photon from 13.5 billion years ago can make its way to us, while a flashlight's beam can barely cover a few dozen feet. This discrepancy is rooted in the distinct nature of the sources of these photons and the properties inherent to quantum physics. Let's delve into why this is the case.
Sources of the Photon and Flashlight Beam
The key to this phenomenon lies in the origins of the photons in question. The ancient photon likely originated from a monumental cosmic event such as the Big Bang or the explosion of a distant star. These events generate photons with immense energy that can traverse vast cosmic expanses. In contrast, the photons emitted by your flashlight are derived from electric current flowing through a bulb, generating relatively modest energy levels.
Energy and Power of Photons
Photons are packets of light energy, and their energy is directly proportional to their frequency or inversely proportional to their wavelength. Higher energy photons carry more power and can travel greater distances. Ancient photons originating from cosmic events like the Big Bang or supernovae have an extraordinary amount of energy, enabling them to traverse billions of light-years. Flashlights, on the other hand, emit photons with lower energy levels, limiting their range and intensity.
The redshift effect, which is a phenomenon where light from distant stars appears more red, is due to the expansion of the universe. The expansion of space causes the wavelength of light to stretch, resulting in a longer (redder) wavelength. This is not due to individual photons becoming red-shifted; rather, it is the consequence of the expansion of space between the source and the observer. High energy photons are more efficiently scattered or absorbed, leading to a greater shift towards the red end of the spectrum when observed from a distance.
Propagation of Photons
As photons propagate through space, they encounter various obstacles such as absorption and scattering. These interactions cause the photons to disperse rapidly, especially over short distances, leading to a decrease in the intensity and power of the light. Cosmic photons with their cosmic origins and high energy can sustain their intensity over vast distances, while the photons emitted by flashlights, lacking the same energy and momentum, cannot maintain their intensity over longer distances.
The ancient photon, with its immense energy and cosmic origin, can withstand numerous interactions and absorb very little of its energy en route. This is unlike the photons from a flashlight, which are vulnerable to rapid dispersion and intensity loss over even modest distances.
Conclusion
The discrepancy in the reach and intensity of ancient photons and flashlight beams is not merely a spatial issue but is deeply rooted in the inherent characteristics of their sources and the properties of quantum physics. While the ancient photon can traverse billions of light-years with minimal loss of energy, the photons from a flashlight struggle to reach beyond a few dozen feet due to their modest energy levels and vulnerability to scattering and absorption.