Tuesday, 14 May 2019

An Overview Of The Wonders Of Space & Our Universe In A Single Blog Post, By A Rookie

"Somewhere, something incredible is waiting to be known."

First Ever Black Hole Picture Katie Bouman

Once again, in this increasingly infrequent series of overviews, I aim to provide a one-stop-shop for all your cosmological queries. As always, this should be treated as another zealot's opportunity to promote discussion about the miraculous wonders of our Universe (of which there are many), and not a scientific paper by an astrophysicist with a litany of qualifications (of which there are none).

So, without further ado, I present to you: a blogger's guide to the galaxy.

Earth & The Solar System

Jumping away from the obvious facts that even 5th graders could tell you (actually I'm no longer sure what 5th graders could tell you these days): what makes the Earth unique? Why does life exist on Earth and not anywhere else to our knowledge? These are some reasons:
  • All stars have a habitable zone or Goldilocks zone, which is the ideal distance a planet should be located from it. It was named after the eponymous fairy tale character that found one soup too cold, one soup too hot and one soup 'just right'. Similarly, planets in the Goldilocks zones are neither too hot or cold, but just right. 
  • This zone is conducive to life due to moderate levels of radiant energy and atmospheric pressure, which consequently support the presence of liquid water. 
  • Earth is in the Goldilocks zone of our Sun. Before we feel special, we should note that so is Mars.
  • Our solar system is conveniently positioned at a considerable distance from other apocalyptic hazards like rogue stars, black holes or supernovas.
  • Earth's dynamic core creates a strong magnetic field that protects us from solar flares.
  • Jupiter's immense size and proximity to Earth attracts most asteroids away from colliding with us. Remember, it took just one asteroid to wipe out dinosaurs.
  • We have been very lucky with climate changes, the current huge gap between ice ages and geological hazards like supervolcanoes to allow a civilisation to thrive for a couple of hundred thousand years.
Habitable Zones Of Stars Goldilocks Zones

Additional Reading: 
  • Warm Welcome: Finding Habitable Planets: Read Here
The Great Filter

Clearly, multiple miracles worked in our favour to sustain life. Let's say we find a new planet tomorrow, then these factors would help determine whether we might find life on it:
  • The probability of that planet being placed in the habitable zone of its solar system
  • The probability of that planet developing a strong magnetic field
  • The probability of the birth of microbes under favourable weather conditions
  • The probability of the birth of oxygen-producing bacteria
  • The probability of the evolution of multi-cellular organisms into animals, and then into intelligent ones
  • The probability of those animals enduring common cyclic hazards of mass extinction like Ice Ages or asteroids
  • The probability of that civilisation not wiping itself out upon reaching super-intelligence.
  • The probability of the star in that solar system lasting long enough for life to sustain on that planet
  • The probability that planet is close to a giant body that can seduce asteroids away
Of course, there are a lot more probabilities that come into play but let us stick with these. It would be easier to imagine this barrier of conjunctive probabilities as a Great Filter. A filter that determines where life would exist on a given planet.

Let's say a reasonable assumption is that the probability of all these factors clicking together is one in 20 million (1/20,000,000).

Taking the billions and billions of solar systems into account, it is estimated that our Universe contains 40 billion Earth-like planets in Goldilocks zones of their respective stars. (that's 40,000,000,000 Earths). Assuming that one planet in every 20 million planets has the probability of creating life, that still leaves us with 2,000 planets that definitely have life?

Solar Flares Solar Storms
Solar Storms

Cheeky note: We haven't taken into contention forms of life that don't require the same living conditions that we do. So it is entirely possible that there exists a separate permutation, probability and estimation for lifeforms that survive on elements other than water or oxygen within this Universe.

Earth-like Planets

Planets Like Earth Kepler 452b
Earth-like Planets

Listing below some popular Earth-like planets that currently meet most prerequisites for sustaining life:

Kepler-62e: Read More
Kepler 62e
Image Source: Kepler-62e

Kepler-452b: Read More
Kepler 452b
Image Source: Kepler-452b

Kepler-62f: Read More
Kepler 62f

Additional Reading:
  • The Six Most Earth-Like Planets, E. Howell: Click Here
Planet Nine

Beyond Neptune, our last recognised planet (my sincere condolences to Plutonians), lie multiple celestial bodies imaginatively named trans-Neptunian objects (TNOs). As more of these celestial bodies started getting discovered, cosmologists were able to perceive a pattern in their orbits. Their orbits approached the Sun from a common angle and were all tilted in a similar pattern.

These observations can be explained if there is a giant mysterious Planet Nine lurking beyond Neptune in our Solar System. The orbit would be opposite to those of the TNOs, hence balancing out the forces.

Estimated to be around 5-10 times the mass of Earth, its immense distance from the sun results in minimal reflection of light. Things are still murky, however, with increasing improvement in our surveillance technology, we should have an answer soon.

So I guess it might be time to rewrite school textbooks, again.

(my sincere condolences to upcoming elementary school students, as well)

Additional Reading:
  • Evidence For A Distant Giant Planet In The Solar System, K. Batygin, M. Brown: Read Here
  • TED Talk: The Search For Planet Nine: Watch Here
Black Holes

Black Hole From Interstellar

This is where the fun truly begins.

When stars way bigger than our Sun die, they leave behind a mass with a gravitational force but no repulsive forces keeping it stable. As a result, the star collapses upon itself, creating a small region of very high density and very high gravitational force.

The gravitational force is so high, that even light cannot escape it. Which means that if you were to point a torch at a black hole, you would not see any light reflect back. If you were to enter a black hole and switch on a torch you would still not see anything in front of you - even if you held the torch right next to your face.

Supermassive Black Hole

Black holes are hard to detect and hard to theorise upon. At the boundary of a black hole (called the event horizon), all our current scientific theories cease to exist and physics does not make sense any more. Once you cross the event horizon, you need to be travelling faster than the speed of light to escape out, which is currently impossible.

The centre of the black hole is generally termed a point of singularity since theoretically, gravity and density are infinite within an infinitesimally tiny space at the centre.

Since physics as we know it ceases to exist beyond the event horizon, people have the liberty to hypothesise anything they wish - including the time tesseract from Interstellar, parallel universes inside black holes and the black hole information paradox.

Time Tesseract From Interstellar
Image Source: Tesseract

Dark Matter

Dark Matter Universe
Image Source: Is Dark Matter Fuzzy

Everything that we can see, around us, is matter. Anyone who has lived a moderately long life can attest to the fact that there is a lot of matter on Earth alone, and we haven't even completely explored our solar system or the universe. Yet, matter only makes up 5% of our universe. The rest is divided into 27% dark matter and 68% dark energy, which effectively means that we don't know, understand, see or interact with 95% of our own universe. 

Dark matter is matter we cannot see, as it does not reflect light or any form of electromagnetic radiation. It is completely undetectable by all measuring instruments we have invented so far. But we know that it exists, or something exists, that exerts a strong gravitational force. That is because visible matter simply does not account for all the gravitational forces we have measured so far. In fact, it falls alarmingly short.

Although far-fetched, one theory suggests that there are parallel solar systems composed entirely of dark matter (like ours is of matter), that we just cannot see yet. 

Dark Energy

Dark Energy Universe

Things get even murkier when we consider dark energy. Dark energy was born out of the discrepancy in common logic: We can all agree that the universe is made up of matter (dark or otherwise). We are also in unanimous agreement that all matter exerts a gravitational force. All a result, we would constantly be pulled towards a bigger mass (the Moon towards the Earth, the Earth towards the Sun, the Sun towards the supermassive black hole at the centre or our galaxy).

This should mean that either

1) The Universe is shrinking, or

2) It is in a state of equilibrium, but a minute quantum fluctuation would send everything spiralling into one another and it would start shrinking like the first scenario

It was then hypothesised that there exists a strong, repulsive force that opposes gravity. We can neither see it, nor measure it at this point but we know it exists simply from the fact that something is pushing galaxies away from each other, in this expanding Universe. That something also happens to constitute 68% of the Universe, and alarmingly, does not weaken the further it pushes objects away from each other.

Some theories claim that dark energy is getting stronger the further it pulls us apart. Aliens are zooming away from us exponentially as we speak.

Einstein's Biggest Blunder

Einstein originally included a 'cosmological constant' in his equations to account for a stable universe. Back then, it was only known that gravity existed as an attractive force. To account for a stable Universe, Einstein assumed a constant negative value for the cosmological constant to oppose gravity. However, when Edwin Hubble discovered that the Universe was expanding, Einstein was forced to discard this constant, as it was clear the Universe was not stable.

He went on record to call it the biggest blunder of his life. His equations still worked - the value of the cosmological constant was just assumed to be zero.

Albert Einstein Cosmological Constant Biggest Blunder

Decades later, astrophysicists made the discovery that the universe is not just expanding, it's also accelerating. When they applied Einstein's equations, they found that they still worked but now the cosmological constant was back in play. Only this time it was supposed to have a positive non-zero value. Somehow, his equations still worked, just the value assumed for the constant was different.

Einstein's brilliance exceeded his own awareness.

Image Source: Big Bang - Expansion

Additional Reading:
  • Dark Matter & Dark Energy: Read More
  • The Great Mysteries of Dark Matter And Dark Energy, Z. Tomlinson: Read Here
  • Brian Cox on Joe Rogan Experience: Watch Here
Aliens & The Fermi Paradox

"Where are they?"

Named after Enrico Fermi's lunchtime discussion with his colleagues, the Fermi Paradox questions the existence of extra-terrestrial life by the simple fact that we haven't been contacted by anyone yet. Having already noted the existence of habitable zones, Earth-like planets and the possibility of advanced civilizations that merely began a millennia before ours, we should have been contacted or have seen some trace of their existence.

But we haven't, which creates a very chilling paradox.

Some plausible theories are:
  • Aliens have already found us and either oversee our lives in ostensibly unnoticeable ways or are simply too advanced to bother with a civilisation with our (low) level of intelligence. Looking at the indifference with which we treat our closest intelligent animals like chimpanzees or dolphins, to aliens out there this could just be an insignificant planet of chimpanzees.
  • We are already in a simulation created by an advanced civilization, or in a Matrioshka brain
  • They visit us from time to time, during Comic-Cons (a theory by Neil deGrasse Tyson, before you throw shoes at me)
  • They have transcended conventional intelligence so far, that mundane and physical manifestations of life no longer interest them. This was also alluded to in the fantastically terrifying Stanley Kubrick film 2001: A Space Odyssey
  • We might actually be the only living creatures in the entire Universe. Casual.
Star Child 2001 A Space Odyssey Stanley Kubrick
Star Child From 2001: A Space Odyssey

Why We Shouldn't Find Life On Mars

Nick Bostrom has gone on record to state that he sincerely wishes we don't find any form on life on Mars, for the following reasons:
  • If the probability barrier or the Great Filter theory for the factors that sustain life is to be believed, then either it has occurred before Earth or will occur in the future. 
  • If the Great Filter has already occurred, then we should have been contacted by other civilizations similar to ours by now, unless we're the only ones. It throws into light the incredibly low probability of life developing under favourable conditions, undeterred by hazards of all forms.
  • If the Great Filter is yet to come, it basically means that all over the Universe life can easily thrive to the levels we have achieved. At some point, their intelligence causes them to self-destruct with mass extinction - either through a bad invention (nuclear missiles anyone?), bad ideologies (any guesses?) or another unforeseen threat. (fatal epidemic?)
The Great Filter

It follows that if we were to discover life on Mars, it would shoot the statistics on the discovery of life to two planets out of eight in just our Solar System. This would severely change the numbers from 1 in 20,000,000+ planets as currently believed to 1 in 4. It would imply that the Great Filter is yet to come since life is much easier to sustain than previously believed.

This would also mean that humanity might come to a premature end in the foreseeable future, since the Great Filter is ahead of us, and not behind us.

Didn't that escalate quickly?

Additional Reading:
  • Neil deGrasse Tyson Thinks Humans Might Be Too Stupid For Aliens To Contact: Read More
  • Why I Hope The Search For Extra-Terrestrial Life Finds Nothing, N. Bolstrom: Read More
  • Supervolcanoes 101: Read Here
Inter-Stellar Probes

The Pioneer Program
was one of our first forays into inter-galactic communication. Multiple probes were sent out into space around the Sun, Moon, other planets, for the purpose of creating a weather network and also for exploring the world beyond our solar system.  Pioneer 10 and Pioneer 11 are two notable probes that successfully exited our solar system. They are currently hurtling through space towards the nearest galaxies.

We have now lost contact with both probes, so the only hope of getting them back is if aliens find them and decide to come looking.

Pioneer 10 Probe
Image Source: The Pioneer Missions

The Voyager probes were initially designed to explore the planets in our Universe. However, they soon received unforeseen promotions and are also currently on an interstellar journey. In fact, much of what we know about Saturn, Jupiter, Uranus and Neptune is due to the Voyager twins. Europa, one of Jupiter's moons, was discovered to one an extremely smooth surface which lead to speculations of an ice-water crust. Combine that with an atmosphere comprising of oxygen, and we actually have the possibility of extra-terrestrial life not too far from us.

Voyager 1 is currently the furthest object we have ever sent in space, at around 21.7 billion kilometres away from home. This should throw things into perspective the next time you can't be bothered to walk to the nearest grocery store.

The New Horizons probe set out to explore the only unexplored planet in our Solar System at the time. I'm pretty sure it must've suffered from some form of existential crisis when midway through its mission it was informed that the planet was no longer, well, a planet. Having conducted its original mission, the probe is now headed towards the Kuiper Belt.

Paths & Trajectories of Voyager, Pioneer & New Horizon Probes

Naturally, if we did take the effort to send probes out to the Universe, we would need to account for the fact that someone might find them? So we decided to put some things onboard:

The Pioneer Plaque

Let's do a simple exercise: what messages can you infer from the picture below?

Pioneer Plaque by Carl Sagan
Image Source: Pioneer Plaque

If you are reading this without performing the mental exercise - how dare you, please go back. If you did, keep a mental or written note to compare with later. Now, it's my duty to inform you that you just tried to decipher a message that might discover aliens, save humanity or be lost in spacetime for eons. The Pioneer plaque was put on board the Pioneer probes, as an eternal, literally universal message to the aliens that might eventually find it.

For the ones who did diligently do this task (and for the renegades) the answers are below:

- The circles on the top left represent the atoms of hydrogen
- The pattern below it denotes the distance of neutron stars from our sun
- The orbs at the bottom denote our solar system, and the paths taken by Pioneer 10 & 11*
- The shape behind the man and woman denotes the Pioneer spacecraft, to provide a size reference for the humans
- If you don't identify the man and the woman, then you might be the alien.**

*Pioneer 11 ended up deviating from its original trajectory, so the alien that finds that plaque will learn an additional tidbit about inherent human traits: deceit

**The man has opposing hand gestures and the woman rests her weight on one foot to indicate the flexibility of our limbs. Carl Sagan had initially (and romantically) intended them to hold hands, but the idea was rebuffed over the possibility of aliens considering man and woman one single conjoined entity. I guess we'll just have to send another plaque for all the soulmates.

Voyager Golden Record

Voyager Golden Record Pioneer Plaque

The Voyager probes carry the Voyager Golden Records, two phonographs that convey the essence of our existence in audio form. The contents include greetings in over 50 languages, sounds of animals, locomotives, sounds of nature, music from all over the globe, over 100 images and an hour-long recording of the brainwaves of Ann Druyan.*

The back of the record includes instructions to use them, along with elements from the original Pioneer Plaque sans the man and woman because some people didn't like the nudity. (not sure if it was the Indian film censor board)

*If you wish to dissent the exclusion of Beatles' music in these records, take it up with Carl Sagan.

Additional Reading:
  • A Message From Earth, C. Sagan, L. Sagan, F. Drake: Read Here

Our Universe doesn't necessarily have a physical boundary, just a limit to the distance we can see. The oldest radiation that we can track dates back to our Big Bang. However, there is unanimous agreement that space doesn't just end beyond our visibility. 

There is a possibility that there are multiple Universes out there, each within their own spacetime sphere of visibility that we probably have no chance of visiting. 

There are a lot of fun possibilities to explore, and I hope this introduction is just the beginning. We have already established the factors necessary to sustain life, and also the elements that created matter. It is very probable to assume that given an infinite multiverse, there would be a Universe just like ours (a parallel universe) where you would've opted for the roads not taken in your life.

Big Bangs From Black Holes

One of the running theories on the Big Bang is that it was nothing but a conventional black hole that exploded. The Universe is expanding at an alarming rate, and matter as we know it is gradually spiralling into supermassive black holes at the centre of each universe. There might come a point where the Universe has expanded so much, that there are only black holes and they are all placed trillions of light years away from each other.

Since space would have expanded so far ahead, the black holes would be the warmest objects to be found. As a result, due to their immense density, temperature and inherent instability they would explode with a Big Bang, expunge all the accumulated quarks and bosons and a new Universe would be born.

This cycle would go on, and probably has, for eternity.

Sir Roger Penrose has speculated that it might be possible for super-intelligent civilisations from a previous eon to have sent us a message. Just before they got sucked into our black hole, they might've coded a message in the only particle that would survive the black hole & the corollary Big Bang: photons.

If only we could read photons.

* * *

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  1. Beautifully written Shalaj, I really enjoyed reading it and thanks to you, many of my fundas cleared (dark energy-dark matter diff)
    High recommendation to anyone wanting to understand time, space, universe and everything in between....live long and prosper.