What is Time?

Time is something that everyone is familiar with 60 seconds is one minute, 60 minutes is one hour, 24 hours is one day and so on. This is known as Linear Time and is something that everyone is familiar with and agrees upon. But consider this, if someone came up to you on the street and asked you to draw time, what would you draw?

You might draw a clock, or a watch ticking every second, Or you might draw a calendar with X's over each day to represent the passing of time. But that's all those drawings would be, just physical representations of the passing of time. Those drawings would just scrape the surface of the Enigma that is time. Something that seemingly runs our lives and is unavoidable can't be explained by even the smartest people on Earth. So what is time and can we prove that time even exists?

Aristotle once said, "Time is the most unknown of all unknown things." That was nearly 2,500 years ago, and it still stands true today. If you were to go to Google and type in, "What is time?", you would find that it says time is a dimension and in many ways it is. When you text a friend and ask them to meet for coffee, you wouldn't give them a place without a specific time.

However, there is a flaw in that definition of time; It leaves too many doors unopened - because time is also a measurement. For example, I was born in the 1990s. That was over 20 years ago If I were to say I was born 18 billion kilometres in the past, that wouldn't make much sense and people would probably look at me like I'm crazy.

With spatial dimensions - the 3D world that we live in - it's very easy to go back and forth between places because these things are essentially fixed in space. If I went to the store to buy groceries and I forgot the milk, I could easily go back and buy some milk. However, the time that it took to do that is unable to be retrieved. It is lost forever into the past.

An object placed in 3D space will stay there almost indefinitely. If I place a bottle on the table, it will just stay there, but that bottle still falls victim to time. See, time is like an arrow - it moves in one direction; forward. Scientists fittingly called this the arrow of time.

If you one day woke up and found yourself floating in the middle of empty space, would you be able to tell which way is up, down, left or right? Probably not. However, time is a much simpler ordeal. See, the time comes from the past, originating at the Big Bang, where our history lies and is fixed.

Through the present, where we are essentially prisoners of, towards the unknown and turbulent future. We can remember things from the past like how I can tell you that this morning I went to the store, bought groceries and then forgot to buy milk. But at the same time, I can't tell you what I ate for breakfast next Thursday.

The arrow of time originated at the Big Bang and has been moving forward ever since. We used the second law of thermodynamics to represent this. It is known as entropy. Think of entropy as a measure of disorder in the universe. 

At The Big Bang, all the matter in the universe was compacted into an infinitely small point. This is considered a very low entropy situation; a very orderly situation. It would be similar to stuffing every sock that was ever made into one drawer. In that situation, you know with 100% certainty where your socks would be. Ever since the Big Bang, all the matter in the universe has been expanding away from each other making the universe a higher entropy system. 

Because of entropy and because of the arrow of time, we have galaxies, stars, planets, and even life. Entropy is the reason that you can tell the difference between the past and the future. It explains why every human is born and then they live and then dies - always in that order. If there were no entropy -- if there were no change in the universe, you wouldn't be able to tell the difference between the year 2017 and the year 1 billion. No matter what you do, time moves forward and doesn't stop for anyone or anything.

At least on the macro scale. See, the arrow of time works and is extremely noticeable on large scales the skills that you and I operate on every day. But at a quantum level time operates differently. Take the situation where you woke up in the middle of space. There, you have no idea which way is up, down, left or right. It's a very unique situation that only applies in the vastness of empty space, but if you come back to Earth, it's very easy for you to orient yourself. The arrow of time works in a similar way. On a macro level -- the big level, it's very easy for you to tell that the year 1900 is different from the year 2018. It's very easy to view the flow of time.

However, on a micro scale, if we look at deep down into the physics that make up the universe, entropy and - subsequently - the time isn't so obvious. If I were to record myself cracking an egg and pouring its guts into a bowl and then I reversed the footage, you would easily be able to tell that the footage had been reversed. However, if I record a pendulum swinging back and forth for five minutes and then reversed the footage and show it to a random person on the street, will they be able to tell that that footage has been reversed? The answer is probably not.

See the arrow of time seems to flow in one direction on the macro scale, but as you take parts of it away and skim it down to the bare bones of particles that make up the universe, time seems to work and flow in every direction; both forward and backward. There are no laws of physics that state the past is any different from the future.

The only reason why you can think about what you want to have for dinner tomorrow as opposed to what you want to have for dinner yesterday is because of the arrow of time; because of entropy, because the universe had a beginning. Or at least it seems like it.

You might be starting to see why the arrow of time and entropy are so important. They quite literally govern our lives and the universe. See the fact that entropy is increasing is well known. It's the reason why life today is the way that it is.

However, not many people are addressing the question that is: "Why was the entropy of the universe so low in the first place?" Well, the answer is simple. It was lower yesterday than it was today. You can take this logic all the way back to the Big Bang. You hear that a lot, "The universe came into being at the instance of the Big Bang." And for all we know as of now that may be true. However, it might not be true.

We have the physics of Einstein's general relativity that allows us to go back to mere seconds after the Big Bang. But after that, our equations break down. That is as far as we can go for now. There is no law of physics yet that states that there wasn't time before the Big Bang and perhaps a reversed arrow of time. We just don't have the science to look that far back yet.

Because the universe is expanding and because entropy is increasing with time, there will eventually be a time where everything in the universe is so far apart from one another that space will essentially be empty. Everything will be too far apart to interact with one another all the way down to the atoms that make up everything in the universe.

However, just as the temperature outside fluctuates day to day, so does the entropy of the universe. Albeit, very small fluctuations are small time scales such as a human life, over unreal time scale such as 10 to the 10 to the 10 to the 56 years. It is possible that quantum fluctuations could cause an extremely random extreme entropy decrease. This would create conditions similar to the Big Bang as we know it and could explain the arrow of time and the origin of our universe.

However, in order to answer these questions, we need to unite quantum mechanics with Einstein's general relativity. This would provide a scientific link between the quantum world of atoms with the macro world of stars, galaxies and black holes in the universe. This is dubbed "the theory of everything" and is something that many scientists are working on right now.

With this theory, we may be able to - for the first time - be able to explain how and why the universe we live in came into existence. And maybe, even prove that the multiverse exists.

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Let's Understand Wormholes

Whether it’s Star Trek, Stargate or Babylon 5 wormholes have been showing up in science fiction for a long time. They are just a super convenient tunnel to another part of the universe, a way for sci-fi writers to send their characters across huge distances in the blink of an eye. And it turns out that they are not just science fiction: wormholes could really exist. But if they do, they are much weirder than anything we could make up.

In physics, a wormhole is known as an Einstein-Rosen bridge. It is named after Albert Einstein and another physicist, Nathan Rosen. They came up with the idea together in 1935 and showed that according to the general theory of relativity, wormholes are a definite possibility. A wormhole acts like a tunnel between two different points in spacetime, which is just the continuum of space and time that makes up the fabric of the universe.

According to general relativity, gravity works by bending spacetime. Planets and Stars act like a weight in the fabric of the universe, creating a curve. It can be kind of hard to picture what spacetime is, let alone what it would mean for it to bend, so physicists often talk about it by using weights on a stretched bedsheet as an analogy. Earth would be like a big bowling ball making a big dip in the sheet and when something gets too close to the planet and it’s pulled in by the gravity, it’s like it’s falling into that dip in the sheet. 

But if spacetime can be curved, it can also be twisted and shaped in other ways, like by connecting two different places with a tunnel. It’s kind of like poking two holes into that bedsheet, folding it over and then stretching the fabric so that the edges of the holes can get together and you just sew them into a tunnel. That’s a wormhole in a bedsheet. But because wormholes don’t seem to violate the laws of physics does not mean that they actually exist; they are just technically possible. And unfortunately, we haven’t yet detected any and we aren’t even sure how they would form.

If wormholes do exist, one reason we might not have spotted them is that they could be hiding behind black holes. A black hole is what happens when there is so much mass squeezed into an object that it ends up with such a strong force of gravity that even light can’t escape its pull. Once you get too close to a black hole, you are toast: there is no escaping from being smashed into oblivion. In the bedsheet model, black holes and wormholes look very similar, they both have a steep falloff that seems to go on forever. Except, with a wormhole, the steep drop actually leads somewhere.

According to general relativity, wormholes could have black holes at each end, meaning that after diving into a black hole on one end, the energy that was once your body could get spewed out somewhere totally different in the universe. Of course, you would not survive that trip. All that would be left is radiation and subatomic particles. Then there are white holes, which are the opposite of black holes: They spew out matters with such force that it would be impossible to enter them. If black holes are infinite weights on a bedsheet, white holes would be like hills: objects pushing up on the bedsheet.

Like wormholes, these are a thing that could exist, the math does check out, we are just not sure how they would form. But we know that if they exist, they could be found at either end of a wormhole, too. So, maybe if there was a black hole at one end of the wormhole and a white hole at the other, we could go in the black hole end and be blasted out the white hole end, Maybe. But you would still probably be crushed by the black hole in the process. Not to mention it would definitely be a one-way trip.

There are a few other problems with wormholes. For one thing, they would probably be dangerous. Sudden unexpected collapse, weird exotic particles, a ton of radiation. In fact, travelling through a wormhole could instantly collapse it, because they would probably be unstable. And then there is the fact that wormholes might not be a shortcut at all. A random wormhole could easily be a longer-than-normal path. Size is also a problem. A real-life wormhole could be too small for us to travel through. Not to mention the travel time, which could be millions or billions of years, making some wormholes pretty useless.

So, that’s a lot of problems. The biggest hope actually comes from how little we know. A lot of this depends on physics that we haven’t quite worked out yet or on facts about our universe’s history and geometry that we just don’t know for sure. Once we have all that figured out, the final barrier would be technology and opportunity. Right now, we definitely don’t know how to make a wormhole and we would have to be super lucky to find one that is useful to us if they exist at all.

So, it’s pretty clear that we won’t be sliding through any wormholes anytime soon. But we know that they could be out there, hiding in some of the most extreme places in the universe. And who knows? Maybe our ideas about wormholes will be totally different in the future. People living just a few hundred years ago couldn’t have even imagined particle accelerators or internet. Until we find one or build one Let's will keep exploring the universe.

Also Read:- Let's Understand Naked Singularities

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Let's Understand Naked Singularities

When people talk about black holes, there is one thing that pretty much always comes up is that Black holes get their name because the infinitely tiny, infinitely dense point in the centre has a gravitational pull so strong that even light can’t escape. The thing is, that might not always be true. For the past half-century — basically, as long as we have known black holes are a thing — astrophysicists have been debating the existence of something that should be a black hole, except it’s neither black nor a hole. They are called naked singularities and if they exist, they will rewrite physics as we know it.

When a star dies, it undergoes a gravitational implosion and starts to collapse in on itself. If the star is massive enough, nothing can stop the collapse and all that matter turns into a single point in space. We call that point a singularity and it has zero volume and basically infinite density. Like with basically everything involving infinity, it’s hard to even imagine what that means. But that’s astrophysics for you things get weird.

A singularity isn’t the same thing as a black hole, but it is what causes the black hole. The term “black hole” refers to everything inside the event horizon, the point where the singularity’s gravitational pull becomes so strong that light can’t escape. It is impossible to see anything inside it from the outside. And if you decided to go inside the event horizon to check out what is going on, you would never get out again. So, sure, for a moment you would be the only person in the universe to actually know what’s happening down there, but you would never be able to tell anyone and you’d be stuck until you died.

In 1965, an astrophysicist named Roger Penrose demonstrated that all black holes must have singularities within them. Makes sense, But he couldn’t prove that all singularities need to have a point-of-no-return event horizon and therefore a black hole surrounding them. In other words, he couldn’t prove that it was impossible for a singularity to be naked. He was pretty sure naked singularities couldn’t exist though, even if he couldn’t mathematically prove it. Four years later, he coined what’s known as the conjecture of cosmic censorship, which basically just says that it’s impossible for a singularity to exist without a black hole around it.

Again, he couldn’t prove it, it was just a conjecture. But it was really hard to imagine how an infinitely dense point could exist without a black hole around it and all these decades later, many astrophysicists still subscribe to cosmic censorship. But not all of them. We have obviously never observed a naked singularity, but that doesn’t mean it’s impossible for them to exist.

This long-running debate actually led to one of many wagers Stephen Hawking has publicly made about astronomical discoveries. In the early 1990s, he bet Caltech Kip Thorne and John Preskill that naked singularities can’t exist. The loser had to, quote “reward the winner with clothing to cover the winner’s nakedness,” which was definitely on-theme. Months later, Hawking actually found mathematical evidence, though, not definitive proof that when a black hole finishes evaporating, it might leave behind a naked singularity.

If the idea of a black hole evaporating sounds super strange well, it is. But it is one of the many quirks of quantum mechanics, which predicts that a pair of particles can spontaneously pop into existence with one on either side of the event horizon. If the one outside has the right trajectory, it will escape off into the universe, leaving the black hole with a teeny tiny little bit less mass. But! Quirks of quantum mechanics didn’t fall within the confines of the bet, so Hawking technically hadn’t lost. 

He had to concede in 1997, though, when computer models found a special case for fine-tuned parameters that would produce a naked singularity from an imploding star. Basically, it’s like trying to balance a sharpened pencil on the pointy end Highly improbable, but not impossible. Hawking made the most of his loss, though — he gave Thorne and Preskill T-shirts featuring a woman in nothing but a towel, along with the words “Nature Abhors a Naked Singularity.”

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So, simulations are able to suggest naked singularities might form if conditions are just right, but what about more general cases? Well, researchers have found that if our universe had a different number of dimensions or was shaped differently than it is, then yes — it could form naked singularities. But all this could mean that naked singularities only work on paper, not in practice. 

We are kinda stuck with the universe we have got. If by chance we actually learn of a real naked singularity floating around out there in the cosmos, though, it could change our understanding of the universe. Mainly because we would be able to study something that’s governed by both quantum mechanics (the science of the very small) and general relativity (the science of the very massive). 

As it stands, these two theories work almost perfectly when you are using each of them on their own, but they don’t play well together. When you try to apply them both at the same time, like when something is both super duper massive and super duper tiny — basically, a singularity — they spit out nonsense answers. But being able to directly observe a singularity would give us the data to either unite them or scrap them for a different theory entirely. A unified theory of the universe would do more than just reveal the secrets hiding in black holes.

Right now, anything that happened before 10^-43rd seconds after the Big Bang is a big mystery because both quantum mechanics and general relativity would apply to it. That is such a tiny fraction of time that you might think it wouldn’t really matter anyway, but, like, those were the very first moments of our universe. In other words, for being infinitely tiny, naked singularities are a pretty big deal.

Also Read:- How Does Google Maps Works?

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Origins Of The Universe

The universe is everything from the tiniest particles to the largest galaxies to the very existence of space-time and life. But how did it all begin? The origin of the universe is the origin of everything. Multiple scientific theories plus creation myths from around the world have tried to explain its mysterious Genesis. However, the most widely accepted explanation is the Big Bang Theory.

The Big Bang Theory states that the universe began as a hot and infinitely dense point only a few millimeters wide, it was similar to a supercharged black hole. About 13.7 billion years ago this tiny singularity violently exploded and it is from this explosion this bang that all matter energy space and time were created. What happened next were two major stages of the universe's evolution called the radiation and matter eras. They are defined by key events that help shape the universe. 

First came the radiation era named for the dominance of radiation right after the Big Bang. This era is made of smaller stages called epochs that occurred within the universe's first tens of thousands of years. The earliest is the Planck epoch no matter existed in the universe at this time only energy and the ancestor to the four forces of nature the super force. At the end of this stage, however, a key event occurred in which gravity split away from the super force.

Next came the grand unification epoch named for the three remaining unified forces of nature. This epoch ended when one of those forces called strong or strong nuclear force broke away. Then the inflationary epoch began during which the universe rapidly expanded, almost instantly it grew from the size of an atom to the size of a grapefruit. The universe of this time was piping hot and it churned with electrons quarks and other particles.

Then came the electroweak epoch when the last two forces electromagnetic and weak finally split off. During the next stage the quark epoch all of the universe's ingredients were present however the universe was still too hot and dense for subatomic particles to form. Then in the Hadron epoch the universe cooled down enough for quarks to bind together and form protons and neutrons. In the lepton and nuclear epochs, the radiation era's last two stages, the protons and neutrons underwent a significant change they fused and created nuclei and in doing so they created the first chemical element in the universe helium. 

The universe's new ability to form elements the building blocks of matter cued the matter era. Much as the name suggests the matter eras defined by the presence and predominance of matter in the universe, it features three epochs that span billions of years the vast majority of the universe's lifespan and includes the present-day. 

The first was the atomic epoch in this stage the universe's temperature cooled down enough for electrons to attach to nuclei for the first time called recombination. This process helped create the universe's second element hydrogen. This hydrogen along with helium atoms dotted the universe with atomic clouds. Within the clouds small pockets of gas may have had enough gravity to cause atoms to collect, these clusters of atoms formed during the Galactic epoch became the seedlings of galaxies. 

Nestled inside those galaxies stars began to form and in doing so they cued the latest and current stage of the universe's development the stellar epoch. The formation of stars then caused a tremendous ripple effect and helped shape the universe as we know it. Heat within the stars caused the conversion of helium and hydrogen and to almost all the remaining elements in the universe. In turn those elements became the building blocks for planets, moons , life and everything we see today. 

This ecosystem of everything was only possible because of the many stages in the universe's development. While countless questions about the origins of our universe remain, It is only a matter of time for some long sought answers to emerge.

Also Read:- The Seventh Planet From The Sun: Uranus

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