Theories Of Existence

Pranshu Sanghai

IX C

The Need To Search For Aliens

In the past couple of decades, the study of life on Earth has revealed the existence of life in extreme environments that were generally thought to be uninhabitable. The organic chemicals needed for life as we know it are found pervasively in and between the stars of the galaxy.

In the past decade we have been detecting more and more planets orbiting other stars. Hence, a compelling question arises as to whether we are alone or not.

Theories To Prove Existence Of Aliens

Many theories have been proposed on whether aliens exists and attempts have been made to prove them.

The most important theories are:• Fermi’s Paradox• Drake’s Equation

Fermi’s Paradox

Enrico Fermi in 1950Conflict between an argument of scale and

probability and a lack of evidence.Definition:The apparent size and age of the universe

suggests that many technologically advanced alien civilizations ought to exist. However, this hypothesis seems inconsistent with the lack of observational evidence to support it.

Drake’s EquationN = R * f p n e f l f i f c L R* = rate of formation of stars suitable for the development of

intelligent life. f p = fraction of those stars with planetary systems. n e = number of planets, per solar system, with an environment

suitable for life. f l = fraction of suitable planets on which life actually appears. f i = fraction of life bearing planets on which intelligent life

emerges. f c = fraction of civilizations that develop a technology that

releases detectable signs of their existence into space. L = length of time such civilizations release detectable signals

into space. N = estimated number of civilizations in the Milky Way Galaxy

whose electromagnetic emissions are detectable.

Current Estimates Made On Drake’s Equation

R * = 7/yearf p = 0.5n e = 2f l = 0.33f i = 0.01f c = 0.01L = 10000 years

N = 7 × 0.5 × 2 × 0.33 × 0.01 × 0.01 × 10000 = 2.31

Criteria For A Planet To Support Life

• Evidence of oxygen• Presence of liquid water• Analysis of reflected light from the

planet to see if the planet has an atmosphere

• Signs of biological activity (ex): Methane

Origin Of Life In The Universe

Impact On Life On Its Environment

Life needs a suitable environment to flourish. It also feeds back and changes its environment.

The way life changes its environment is known as a biosignature – a sign of presence of life.

Oxygen in Earth’s atmosphere is a biosignature of life, inferred from the presence of photosynthetic life if there is atmospheric oxygen.

Most of the life on Earth is made up of microbes, not animals or plants.

Animals and humans make up only 1% of life on Earth.

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Search For Alien Life

Astrobiology: Studying life on Earth to aid the search for life beyond Earth — microbial life in “extreme environments”

Planetary Exploration: Exploring planets in our solar system with robots — Mars rovers seeking signs of past surface water

Finding Extra-solar planets: Searching for Earth-like planets orbiting distant stars — NASA’s Kepler Mission.

Looking for Signs of Life: Learning how to measure the composition of the atmospheres of extra-solar planets to detect signs of life.

SETI: Seeking electromagnetic signals from a technological civilization.

Astrobiology

The search for extraterrestrial life is the central theme of astrobiology.

This includes a search for signs of other intelligent civilizations, which may be using EM radiation or other means of communication.

The only practical method of investigating the extra-Solar System universe is by spectral analysis of the radiation reaching Earth from such systems.

These include the familiar visible spectrum, other wavebands of the EM spectrum and occasionally, particles of matter.

The latter may range in size from protons to meteorites and comets.

Nasa Terrestrial Planet Finder

In a decade or so, TPF's spectroscopy should allow atmospheric chemists and biologists to use the relative amounts of gases like carbon dioxide, water vapor, ozone & methane to find whether an extra-solar planet may support life. NASA’s Terrestrial Planet Finder (TPF) Spacecraft

SETI

• SETI – Search for Extra Terrestrial Intelligence

• The SETI Institute uses radio and optical telescopes to search for signals that might be emitted by technologically advanced life.

• The Allen Telescope Array is being developed at Hat Creek, CA to greatly expand the SETI search.

Video On Aliens

So ultimately, there are only two possibilities:

Maybe we’re alone… Or… Maybe we’re not………

My acknowledgements to my father to let me use the computer to complete my project

I would also thank websites like Nasa for their ACTUAL research in real time Space.

Project made by Pranshu Sanghai