Category Archives: aliens

aliens, Astrophysics

Are we alone?

About 13.8 billion years ago, there was nothing..and then, bang! The universe was created. When the universe was only 200 million years old, it gave birth to stars. Slowly stars became very common in the universe. After many many years, our star, the head of our solar system, the Sun was born. The solar system was a violent place then. The mass emitted by the sun created small rocky bodies, one of which was the Earth. The Earth is a little over 4.5 billion years old, with its oldest materials being 4.3 billion-year-old zircon crystals. To date, we have no evidence as to how life came into being. Theories say that bacteria were brought to the earth by an asteroid, some say that it was aliens who ruled the planet and left it after mass destruction, whereas some theories say that there was a chemical reaction between water and organic elements (which created amino acids) on being hit by lightning.

Unicellular cells developed to form complex organisms like us which had the ability to think and reason. As there was a development in education and space sciences, one major thought kept hitting everyone’s mind – “Are we alone?”. The Universe is a huge place. It is a waste of space if we’re the only ones living in it. Come on.. there have to be aliens right?

There are about 100,000,000,000 galaxies in the known universe. Each galaxy has 100,000,000,000 to 1,000,000,000,000 stars. Planets also appear to be common in every solar system observed so far. The milky way itself has 400 billion stars i.e. 10,000 stars for every single grain of sand on earth! Then why have we not been contacted by aliens till now?

Drake’s Equation and Fermi Paradox

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drake equation

The Drake Equation is:
N = R * fp * ne * fl * fi * fc * L

where:
N = The number of broadcasting civilizations.
R = Average rate of formation of suitable stars (stars/year) in the Milky Way galaxy
fp = Fraction of stars that form planets
ne = Average number of habitable planets per star
fl = Fraction of habitable planets (ne) where life emerges
fi = Fraction of habitable planets with life where intelligence evolves
fc = Fraction of planets with intelligent life capable of interstellar communication
L = Years a civilization remains detectable

You see, it’s so easy to calculate the number of alien civilizations in our galaxy! Hahaha..just kidding. The Drake Equation appears extremely pleasing on a piece of paper but is unrealistic (according to me). So do we conclude that we’re alone? Not so early.. We are probably forgetting about The Fermi Paradox.

The Fermi paradox is named after physicist Enrico Fermi, which is the apparent contradiction between the lack of evidence and high probability estimates for the existence of extraterrestrial civilizations. It is a conflict between probability and evidence. It also states that we could be protected under a shield that does not allow us to contact other intelligent beings.

aliens, Astrophysics

WOW! Signal

Are we alone? Do aliens exist? These are some questions which keep bugging us all the time. In the late 1900s, technology was developed enough to give scientists a sense of confidence about extraterrestrial life.

How strange would it be if there were aliens? “We are alone” and “There’s somebody out there” are two possibilities, each equally scary. To address this major dilemma, scientists initiated a project called SETI—the Search for Extraterrestrial Intelligence—in 1997. The purpose of this mission is to send and receive radio signals from intelligent life in deep space. Beyond SETI, numerous other radio telescopes have been searching for similar signals.

In 1959, Cornell physicists Philip Morrison and Giuseppe Cocconi speculated that any extraterrestrial civilization attempting to communicate via radio signals might use a frequency of 1420 megahertz. This frequency is naturally emitted by hydrogen, the most common element in the universe, and therefore likely familiar to all technologically advanced civilizations. In 1973, after completing an extensive survey of extragalactic radio sources, Ohio State University assigned the now-defunct Big Ear telescope to SETI.

On August 15, 1977 The Ohio State University’s Big Ear Telescope received a weird signal which couldn’t have been created naturally. The signal appeared to come from the constellation Sagittarius and bore the expected hallmarks of extraterrestrial origin. Astronomer Jerry R. Ehman discovered the anomaly a few days later while reviewing the recorded data. He was so impressed by the result that he circled the reading on the computer printout and wrote the comment Wow! on its side, leading to the event’s widely used name.

The Signal

The entire signal sequence lasted for the full 72-second window during which Big Ear was able to observe it, but has not been detected since, despite several subsequent attempts.Wow_signal_profile.svg

This represents the intensity variation of the radio signal over time, measured as unitless signal-to-noise ratio. A common misconception is that the Wow! signal constitutes some sort of message. In fact, what was received appears to be an unmodulated, continuous wave signal with no encoded information; essentially a flash of radio energy.

Two different values for the signal’s frequency have been given: 1420.36 MHz (J. D. Kraus) and 1420.46 MHz (J. R. Ehman), both very close to the value of 1420.41 MHz of the hydrogen line.

Hypothesis

  1. Interstellar scintillation of a weaker continuous signal : This basically means that the signal might not be real but an illusion like the twinkling of stars.
  2. Reflected signal : An earth sourced signal could have been reflected by some debris in space.
  3. Hydrogeb could surrounding two comets : Antonio Paris proposed that the hydrogen cloud surrounding two comets, 266P/Christensen and 335P/Gibbs, now known to have been in roughly the right position, could have been the source of the Wow! signal.

Well, the signal couldn’t be replicated again and there is no definite information about its source. Could they be aliens? Nobody knows!

These efforts are driven by the profound curiosity and desire to answer one of humanity’s oldest questions: Are we alone in the universe? The discovery of extraterrestrial intelligence would revolutionize our understanding of our place in the cosmos, while the confirmation of our solitude would deepen the mystery of life’s origins on Earth. Regardless of the outcome, the quest to find intelligent life beyond our planet continues to inspire scientific innovation and exploration.