Eureka!

When we come across this Greek word-Eureka, it reminds most of us about the Archimedes’ Principle. Archimedes discovered the method of detecting the amount of alloy mixed with gold in the crown of the King of Syracuse.

However, you might be wondering how this word is related to anything in astronomy. It is not the exclamatory word, but the word with interrogations which makes a difference.

We are surrounded by a countless number of stars. Some of them are still in early stages of their life in nebulae, while some of them have died gloriously and have undergone metamorphosis to become supermassive black holes. Today, we know that stars, black holes, quasars, pulsars and neutron stars are all not just mere science fiction. We are surrounded by these wonders from all the sides. In reality, we are a wonder ourselves. The probability that a pale blue dot thrives with life is smaller than the chances that matter can pass through a wall!

However, there have been many theories about how life came into being on Earth. No matter what any theory suggests, the ultimate validation for any theory is its correspondence with reality. This reality is embedded within us, we are the reality.

“In essence, science is a perpetual search for an intelligent and integrated comprehension of the world we live in.” is rightly said by Cornelius Van Neil. Science is always in the quest of truth, be it the theory of evolution of humans or the universe. In this quest, the most decisive factor in the fate of the dynamic theory of evolution of universe or the commonly known “Big Bang” theory was the prediction and the discovery of Cosmic Microwave Background (CMB).

Big Bang model essentially claims that the universe emerged from a state of extremely high temperature and density- the PRIMORDIAL STATE. In layman’s terms, Universe exploded from a single mother-of-all atom. This state which contained in it the entire Universe was in plasma. In this state, the temperature is so high that matter is a mixture of unattached nuclei and electrons. This Universe also contained in it an important ingredient, namely an overwhelming sea of light.

Light interacts easily with charged particles, such as the electrons. This light would have scattered repeatedly off the particles in plasma, resulting in an opaque universe. As time passed and the temperature dropped, matter would no longer be able to exist in plasma state. This lead to the formation of neutral atoms. Thus, the cosmic fog of plasma was lifted and the behavior of light changed dramatically. The sea of light started sailing through space unhindered, for the first time in the history of the Universe.

This sea of light which existed from the moment of recombination, was estimated to have a wavelength in the microwave region now. These estimates were done by taking into consideration the thermal conditions in PRIMORDIAL STATE and the expansion of Universe. As this light existed from the beginning of space-time, it should exist in all directions. Hence this light was known as “COSMIC MICROWAVE BACKGROUND”.

This light existed from the beginning of space-time, hence today, it should exist in all directions. It is like a constant humming of the universe, which is bombarded on our body from everywhere. It was estimated that these electromagnetic waves should now have a frequency in the microwave region. Hence this light was known as “COSMIC MICROWAVE BACKGROUND”. The discovery of CMB proved to be the most groundbreaking one for astrophysics in the entire century. However, it’s discovery was nothing but an act of serendipity.

In the Bell Laboratories situated in Crawford Hill of NJ, Robert Wilson and Arno Penzias were dedicated to eliminate noise from the radio signals and scan the skies. Here ‘noise’ is a technical term used to describe any random interference that may obscure the original genuine signal.

Robert Wilson and Arno Penzias at the Bell Laboratories

However, their dedication had turned into an obsession. Once, they thought that the ‘white dielectric material’ deposited by the pigeons on the horn antenna might be the cause of the noise! After a year of checking, cleaning and rewiring of the radio telescope, there was a reduction in the level of noise. After devotion of an immense amount of time, effort and money into understanding and minimizing the noise, yet, there was still an element of noise that was both mysterious and incessant.

Something, somewhere, somehow was emitting radio waves all the time from all the directions.

The pigeon trap installed at the Smithsonian Museum which was a mark of the concerted effort by Robert and Penzias in order to eliminate the distortion in radio wave signal caused by the birds in the vicinity

These two frustrated radio astronomers had discovered the evidence which validated the Big Bang model. They had stumbled over the Cosmic Microwave Background in the quest for the most genuine radio wave signal. However, calling their discovery a mere fluke would be an insult to the ruthless persistence of Robert and Penzias.

The CMB is the furthest in time we can explore using light. It formed about 380,000 years after the Big Bang and imprinted on it are the traces of the seeds from which the stars and the galaxies we can see today eventually formed. Hidden in the pattern of the radiation is a complex story that helps scientists to understand the history of the Universe both before and after the CMB was formed.

The first space mission designed specifically to study CMB was NASA’s Cosmic Background Explorer launched in 1989. Its’ key discovery was the slight temperature fluctuation about 1 in 100,000 that it detected. These fluctuations were originated at an earlier epoch- immediately after the Big Bang- and would later grow, under the effect of gravity, giving rise to the large scale clusters of galaxies that we see around us today.

The full sky map of the predicted CMB anisotropies

CMB was observed several times, however, it was dusted away and assumed to be unwanted.

We were always surrounded by this silent humming of Universe, but Robert and Penzias had the patience and insight to listen and comprehend it. We are too naïve to draw a sensible conclusion and value its importance.

The interrogative punctuations in the title indicate our lack of wisdom, inability to fathom the veracity of our being, of our existence.

We all have dipped a container in water or taken a bath in a tub. But it was Archimedes who had the vision and tenacity to realize the science and comprehend the truth.

Astrophysics, is the concerted human effort to understand better, the truth that resonates with the existence of our universe. We must all widen our horizons of observation, metaphorically as well as literally, to have a better understanding of our being, of our existence.

As rightly said by Neil deGrasse Tyson, “We do not simply live in this Universe. The Universe lives within us.’’

– Aditi Marathe,

Second Year

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