The night sky has trillions and trillions of stars we could ever imagine. many of these are visible to the naked eye on a clear night. We can also see some of the planets that orbits our Sun as well as the moon. all these objects are part of our universe.

Our Universe

However, they aren't only part of our universe. The stars and planets that we can see are only tiny part of everything that's out there. The Observable universe is a sphere that is a little over 90 billion light years in diameter. The rest of it is invisible to us because the originating light, post the big bang hasn't even reached us yet.

The Big Bang

Big Bang Theory. It is the modern theory in terms of the origin of Earth and it is widely accepted explanation for the existence of our universe. This model was proposed by Russian mathematician Aleksandr Friedmann and Belgian astronomer Georges Lemaitre during the 1920s. In Big Bang Theory scientists decided, let's look at the larger picture, let's find out how the universe came into existence. So whenever you hear the word Big Bang, you must immediately recollect that it is about the expanding universe hypothesis. So basically it is an effort to explain what happened at the very beginning of our Universe. Now many discoveries in astronomy and physics have shown beyond a reasonable doubt that our universe did in fact have a beginning. Prior to that moment, there was nothing. During and after that moment, there was something that is a universe. The Big Bang Theory is an effort to explain what happened during and after that moment. So how did we come to this conclusion? In 1929, Edwin Hubble formulated the Redshift Distance law. The observance of increasing "redshift" in more distant starts proves that the farther galaxies were receding. Edwin Hubble is the same person after whom the famous Hubble telescope is named. He mentioned as time passes, galaxies move further and further apart.There is an experiment associated with it. Take a balloon and mark some points on it to represent the galaxies. Now if you start inflating the balloon, the points marked on the balloon will appear to be moving away from each other as the balloon expands. Similarly the distance between the galaxies is also found to be increasing and thereby the universe is considered to be expanding. But I want you to notice this. Besides the increase in the distances between the points on the balloon, the points themselves are expanding but in reality the scientists have no real evidence about the expansion of galaxies, but they do believe that the distance between galaxies is increasing. Hence we can say that the balloon example is only partially correct.

Now The Big Bang theory considers the following stages in the development of the universe. In the beginning, all matter forming the universe existed in one place in the form of a tiny ball that is singular atom with an unimaginably small volume, infinite temperature and infinite density. Well, to be honest. Where did it come from? We don't know. Why did it appear? We don't know. It is thought to exist at the core of black holes. Black holes are areas of intense gravitational pressure. The pressure is thought to be so intense that finite matter is actually squashed into infinite density. It's a mathematical concept which truly boggles the mind. Now, in the second stage, this tiny ball exploded violently. This led to a huge expansion, the universe that we know was born. Time, space and matter all began with The Big Bang. In a fraction of second the universe grew from smaller than a single atom to bigger than a Galaxy and it kept on growing at a fantastic rate. It is still expanding today. It is now generally accepted that the event of Big Bang took place 13.7 billion years before the present. Now within the first second of The Big Bang, some energy was converted into matter and antimatter. These two opposite.Types of particle largely destroyed each other, but some matter survived. Most stable particles called protons and neutrons started to form. Protons are positively charged and neutrons are negatively charged particles. Over the next 3 minutes the temperature dropped below 1 billion degrees Celsius. It was now cool enough for the protons and neutrons to come together, basically attract to form hydrogen and helium nuclei. After 300,000 years, the universe had cooled to about 4000 degrees, atomic nuclei could finally capture electrons to form a fully fledged atoms. Then the universe became transparent and got filled with clouds of hydrogen and helium gas. So this is the story of the universe, otherwise known as The Big Bang Theory.

What was there before the Big Bang?

There are plenty of theories about how our universe began, but currently the most prevalent scientific theory is that everything came into existence at a single moment known as The Big Bang. But if everything was created at this one moment, what came before The Big Bang?

Over the years, our space telescopes have allowed us to look further and further back in time Observing the faintest lights of the universe that formed just 300,000 years after The Big Bang. To gain an even better understanding of the beginning of the universe, scientists use the Large Hadron Collider to approximate the conditions of The Big Bang. On a much smaller scale, of course. But that's as far back as we can go, and that's just not good enough, is it? We humans are wired with an innate tendency to assume cause and effect. Everything that happens can be assumed to have a cause, or it wouldn't have happened, right? So if we rewind time back through the expansion of the universe before galaxies formed to the moment before the explosion that caused everything. What do we find? Well, maybe nothing.

Some scientists speculate that before The Big Bang was a massively dense, infinitely tiny singularity, a point at which time and the laws of physics did not exist. Therefore, the idea of something coming "Before" couldnt exist either. Big Bang may actually have been a big bounce. Another universe may have existed before ours that after many billions of years stopped expanding and collapsed on itself and formed a single, unbelievably massive black hole, eventually collapsing into the singularity that exploded into our current universe. Proponents of the idea suspect that this big bounce could have been occurring forever, and will continue to happen forever. but what caused the first universe in this series? No one knows for sure. Perhaps the first universe was always there, and our human understanding is not equipped to accept that fact. Albert Einstein once said that trying to understand what came before The Big Bang is like trying to figure out what's more north then the North Pole.

Another hypothesis is that our universe is just one of an infinite number of universes, each floating around in some higher dimension. Some scientists suspect that the expansion of our universe, and potentially any universe, is the effect of a neighboring universe's gravity. And when two or more of these universes collide with each other, it should leave a distinctive marking in the cosmic microwave background, which we should be able to detect. The only problem is we haven't ever detected anything of the sort. Others proposed that a collision between universes would spark a cataclysmic event i.e. a Big Bang and create an entirely new universe. So really the only honest answer anyone can currently give to the question of what came before The Big Bang is we don't know.

Other Theories of our Universe

The Big Bang is the most popular theory in todays time. However there are and probably always will be other theories competing with this one. Some of the originally proposed theories have already been discarded. A theory is discarded if what has been observed of the universe does not match the predictions of the said theory.

Some of the more theories are explained below:

Oscillation Model Theory: It states that the universe is a cyclic process. it started with a Big Bang and will continue till the universe expands to its maximum size. its combines The Big Bang theory and the Big Crunch. The Big Bang theory was proposed by George Lemaitre whereas big crunch created by a French mathematician, Andre Leichner Ovich.This theory states how the universe eventually stopped expanding then it will start the contracting. It is also known as cyclical model so it will never explode.

Steady State Theory: In this theory it is believed that the universe has no beginning or end. New Matter is being Continuously created as the universe expands. This theory doesn't predict any age or a distinct point of origin. The idea was originally proposed by Sir James Jeans during the 1920s.

Hawking-Turok Theory: This theory states that the universe was created from a tiny particle like a pea. What this particle was made from is yet to be explored. but that is how it began. it co-exists with the big bang. Rather than explaining the big bang itself, it tries to explain that the big bang needed an impetus. This impetus was provided by a particle that they describe as an "instanton". The instanton is a hypothetical particle that has mass of pea but much, much smaller in size. As a result of this basic assumption, the theory is also called the "universe from a pea" theory.

Eternal Inflation Theory: According to this theory, the rapid expansion following the big bang never really stopped. it just continued in other universes. Thus, the inflation is "eternal". in theories of eternal inflation, the phase of the inflation of our universe's expansion will never end.

Wormholes

Things of mere science fiction or unobserved natural wonders? Well, right now they're only a theoretical field, but who knows what the future holds. A Wormhole is a proposed structure that links two places in space-time together and is usually visualized as a giant tunnel linking to wider mouths or entry and exit points. You've probably seen the paper example in various films or demonstrations. When two dots are drawn at opposite ends of the paper, the paper is folded in half before someone pierces it, connecting the two dots with pencil. This example is used in so many movies because it's probably the best and easiest way to show the phenomena. The concept itself links up with Einstein's theory of general relativity, the equations for which account for Schwarzschild wormholes or Einstein Rosen bridges, which essentially act as massive black holes linking to areas of space-time. The theory suggests that the matter in light that is sucked into a black hole on one end is spat out at the other at a point known as a white hole. This white hole would be located somewhere else in the Galaxy, or perhaps even in another dimension. These theoretical. Wormholes could be utilized for a variety of different things. Some say that they could be used for faster than light travel as part of a far off future existence when advanced beings can zap between galaxies with wormholes, creating a massive shortcut between any two destinations.

Traveling at Lightspeed Seems and currently is impossible, but we could feasibly travel faster than light using a wormhole if two massively separated points are connected in this way. It would likely be far faster to travel through the wormhole than it would be for light to conventionally travel between the two locations, therefore, even though an object is traveling slower than light inside the wormhole itself, it would still reach its destination before a beam of light outside.

Some have argued that wormholes could allow for time travel. Theoretical physicist Kip Thorne provides an example in his book Black Holes and time warps. As an experiment, Thorn and his wife hold on to two ends of a wormhole. Thorne remains at home with his end, while his wife takes hers onto a spaceship that can travel at the speed of light. She shoots into space for six hours, turns around, and comes back home, accounting for 12 total hours of lightspeed travel the entire time.
Thorn and his wife are connected via their wormhole, can see each other, and even hold hands. However, Thorne might struggle to physically greet his wife when she returns from her 12 hour trip because she has traveled at the speed of light and time has slowed on her end of the wormhole. 12 hours for her would equate to about 10 years on Earth. So when she finally lands back on Earth, she'll be 10 years into the future and her husband will be 10 years older still with us. We've yet to account for the wormhole itself, though Thorne's wife, who's now 10 years into the future, can look through her wormhole and see her husband, who's only 12 Hours ahead. Therefore, if she were to step into the wormhole, she'd traveled 10 years back in time. Similarly, Thorne could theoretically stepped through his end of the wormhole and travel 10 years into the future. Just blow this up onto an interstellar scale and you have a basic concept of time travel via wormhole. And it's not the only way in which wormhole time travel could be possible either.

There are also theories surrounding significant gravitational fields. For example, say we could place one end of a wormhole close to a black hole which exhibits incredible amounts of gravity and acts to slow down conventional time.The link between that place and somewhere experiencing time as we usually would could provide a means of traveling to or from the future. So that's lightspeed and time travel ticked off of our ultimate bucket list.

Next up, Inter universal travel or traveling to other dimensions. This theory relies on the many worlds hypothesis, an interpretation of quantum mechanics that posits infinite universes and timelines. According to this idea, every choice or branching path that we and everything else refrained from taking on our own timelines exists in an endless list of others. For example, let's say you chose to attend X university instead of Y college? Because it was closer to home. In this universe. You actually do go to x university, but there also exists a universe where and you moved away from home to the other college. Now let's say you're in possession of your own personal wormhole, similar to Kip Thorne and his wife. Theoretically, if the many worlds interpretation is correct, there would exist countless versions of you with the same wormhole. Therefore if we could somehow manage to travel between them, we could visit ourselves in different timelines. Of all the options, this is arguably the least likely scenario, primarily because we aren't even sure if the many worlds Interpretation has any basis in reality. With that said, these are all least likely scenarios in a way because scientists aren't even sure if wormholes exist. Yes, they exist in theory, but there's no empirical proof that they are there. The entire idea is still far, far more science fiction than fact.

Experts like Stephen Hawking have suggested that wormholes could be all around us, but their microscopically small, existing within the very fabric of space-time as nothing is completely flat or solid. According to this theory, within every piece of matter, and even in time itself, there exists incredibly implausibly small holes and wrinkles, as in smaller than atoms small. However, because they're so incredibly tiny, we can't ever wish to travel between or manipulate them. In fact, even if conventional wormholes did exist, there'd still be another major problem preventing human travel their stability.

The predicted Einstein Rosen bridges would simply collapse far too quickly for travel to ever be possible. However, if we introduce some form of as of yet entirely unknown exotic matter into these wormholes, something that exudes negative energy and would expand, then we could potentially prop them open to allow for interstellar journeys. But that's a fairly sizable and completely theoretical if one current contender for such a force could be dark energy, the largely unknown form of energy responsible for the expansion of the universe. However, we don't currently understand even the basic physics behind dark energy. So rounding it up and manipulating it into opening wormholes, which may or may not exist, is clearly out of the question.

Another potential candidate is something called the Casimir effect, wherein metal plates are used to limit the number of electromagnetic waves at a certain point, creating a so-called negative density which could add an incredible stretch be used to stabilize a wormhole. But even the experts tend to agree that this isn't a viable option, as the effect wouldn't be strong enough. And there's one final problem to contend with too, when we consider simply entering the wormhole itself the extreme Densities and energies required to rip open and retain a wormhole aren't likely to create an especially hospitable environment. The extreme conditions needed would almost certainly kill any human who enters it, unless we've developed some form of indestructible tech to travel in by then we'd probably be turned into Jelly or something even worse far before we made it to the other side. For all manner of reasons, wormhole travel of any kind appears impossible for us mere mortals all in, even if Hawking and Co are right and wormholes do exist on a beyond microscopic level we currently have no idea how to identify, manipulate them or open them up. And if conventional sci-fi like wormholes are a reality within the reaches of space, they're almost certainly unsuitable for human travel. The laws of physics and biology simply won't allow it. On the plus side, that wormholes theoretically exist is an exciting thought. Sure, there's no definitive or observable proof, and even if there was, we couldn't even attempt to travel through them for a long, long, long time. But the possibilities they potentially pose will continue to fuel imaginations for generations to come.

Will The Universe End?

Present Universe

Our Universe is huge and includes those things that we can see and know about as well as those that we cannot. The Planets, stars and galaxies comprise only a small part of it. The part of the universe that we can see is called the observable universe. it is currently about 91 billion light years in diameter. The size of the entire universe is unknown and may be infinite. There are probably more than a 100 billion galaxies in the observable universe. Presently, our universe is made up of the following elements:

Energetic Universe: There is a lot of energy in our universe. it helps us to understand and learn about its infiniteness. There are both positive and negative energies present. However, light energy allows us to see the objects in our universe. The energy present in celestial objects helps us to get a better understanding of it. Another form of energy that exists in the universe is that if the X-rays.
Distant Quasar: Quasars are extremely bright distant galaxies powered by supermassive black holes at their centers. Their light may help us probe the period when the first stars and galaxies were forming. Quasers are studied through telescopes both on earth and space.
Galaxy Group: Studies suggest that galaxies exist in groups. Galaxies that are part of such groups frequently interact and even merge together in a vibrant cosmic merging of Interacting gravity.
Star Cluster: When the stars are born, they grow from large clouds of gas. As a result, they form in groups or clusters. After the remnant gas is heated and blown away, the stars come together due to gravity.
Star Birth: Stars are born when clouds of gases and dust collapse. Due to this, their density and temperature increases. The temperature and density are highest at the centre of the cloud, where a new star eventually develops. The object that is formed at the centre of a collapsing cloud and which later grow into a star is called a "protostar".
Planets: Planets form one aspect of our universe. There are 15 planets in our solar system. However, of these only eight planets orbit the Sun. Interestingly, evidence shows that there are several other planets in other galaxies.
Small Worlds: Besides the galaxies, stars and planets, there also exist objects that float around in space. These objects include comets, asteroids, meteors as well as moons of the other planets.
Unknown Universe: Scientist suggest that our universe is composed as follows:
Approximately 68% dark energy, 27% dark matter and 5% normal matter. Studied about dark energy continue to astonish scientists as very little is known as of yet.