Are We Alone?
|SETI – Radio Telescope|
Radio telescopes have been scanning the regions of space since 1977. We are yet to receive signals that points to a communication from intelligent life. There are 60 million potentially habitable planets in our Milky way alone. And there are billions of galaxies in the known universe.
|Cosmic Rays shower|
These are high energy photons that streams through the galaxy and interacts with the air molecules high in Earth’s upper atmosphere creating showers of charged particles. The origin has been a mystery and scientist suggested that remains of supernova might be their source when they explode marking the death of biggest stars. Or the particles could be accelerated by black holes from outside of our galaxy. The energy of these photons is higher than anything what most powerful particle colliders on Earth can produce.
Dark Matter/ Dark Energy
|Big Band Timeline|
Dark matter is hypothetical mass/energy existing in the universe that is causing the expansion. Since gravity is attractive force, the universe would collapse if not for this undetected energy. Roughly 68% of the universe is dark energy and dark matter makes up about 27%. What we can observe is only 5% of the universe. Since it absorbs light, dark matter cant be seen. Einstein tried tacking this issue by introducing a cosmological constant but he gave up the notion and described as the biggest mistake of his life.
Re-Ionization of Universe
|Dark Energy Formation Timeline|
Re-ionization refers to the period in history of universe after Big Bang event when the universe was opaque and dense, turned into a transparent universe from the neutral intergalactic medium through ionization. The universe was initially unobservable because of the neutral medium, any short wavelength radiation emitted would be absorbed quickly by atomic gases. Physicists believe the gravitational collapse of over-dense region gave rise to first stars, galaxies and quasars.
When a star runs out of fuel, it explodes into a supernova, expelling debris up to velocity of 30,000 km/s. the mechanics of how and what happens in the core of exploding star is a mystery.
When a large star with massive mass explodes and the gravitational force collapses on itself, a black hole is formed. The pull from gravity is so extreme that even the light particles can not escape and since we cannot see it, its called a black hole. Scientist believe that some of the smallest black holes are just one atom in size but their mass is of a large mountain. Black holes were first hypothesized from Einstein’s theory of relativity which deduced it’s existence though mathematical formulas from the theory. Since black holes cannot be seen, indirect measurements gives an idea of its existence. Light from other sources will bend near a black hole. Physicists study this bending of light to find existence of a black hole.
|A stellar-mass black hole in orbit with a companion star located about 6,000 light years from Earth.|
Ultimate fate of Universe
|Story of the universe|
There are possible outcomes that physicists believe will be the outcome of the universe. Some believe the theory that universe is flat and will expand for ever while some believe it is tied to the physical properties of mass/energy in the universe. There are several theories explaining the fate such as Big Rip, Big Crunch, Big Bounce, multiverse, Flat vacuum, cosmic uncertainty, Big freeze, Big heat death etc.