Saying the universe is incomprehensibly massive, so much so only the brightest and closest objects and phenomena are visible to the naked eye. Throughout history people have had work arounds, be it using devices to mark inclination of stars to focusing light through telescopes to make the faintest bodies visible. One of the most interesting developments in observational astronomy would be the development of interferometry.
To explain how interferometry works, first let’s explain how light moves through space. Light is traditionally made through the vibrations of charged particles, giving it the form of a wave. Scientists knew this since the 17th century, however the issue is that most waves as they know it as a medium. A popular theory behind this medium in the 20th century would be the luminiferous aether, which physicist Albert A. Michelson and Edward W. Morley in attempted to study in the Michelson Morley Experiment. While the experiment failed in determining anything about aether, it show that light can undergo interference. The results of this experiment were also some of the key stepping stones to special relativity helping explain how light does permeate through space
Source: Renishaw
The above shows how a general interferometer is made. The coherent light source emits light that all have the same wavelength and phase. Through the mirror some fraction of the light is deflected while some pass through. Eventually both divided streams of light reconvene at the detector. However, since both streams of light have travelled a different distance so they may no longer be in the same phase anymore. So initially the wave may have looked like this:
But now recombined they look like this (Each wave has half the amplitude as the one above):
Or in more extreme cases:
This shift net visible light being dampened when compared to the initial intensity. This is similar to if you end up pushing on a swing while the chair is still moving towards you. This shift is proportional to how much distance the two streams travelled compared to each other and is incredibly sensitive. This sensitivity allows for the observation of very minute phenomena.
LIGO the primary detector of gravitational waves uses this exact method to detect them. Through mirrors that are 4km apart to reduce outside interference slight disturbances in space caused by gravitational waves can be detected through the interference of light and measuring the intensity of the interference as a function of time can show how much the wave strains space over time.
Interferometers can also be used to amplify light as well, since if two separate locations were to gather light of the same wavelength, then corrected the phase shift and combine the information, that basically turns an array of smaller telescopes into one very power lens able to render images of the farthest corners of the universe. This technique is how the picture of Sagittarius A*, the blackhole at the center of the milky way, was taken,;which can be seen below.
Even at our limited resources and perspective, through the application of physics and mathematics into advanced instruments the universe ends up looking far brighter than ever before.
• Noah Herrero
