TIME
“The Universe is full of magical things patiently waiting for our wits to grow sharper.” Eden Phillpotts, A Shadow Passes.
Evidently, everyone has asked themselves “Why are we here” at some point in their lives. I had this, at least. However, as I got older, I began to forget the questions that had intrigued me as a child. But the past began to retaliate as I entered my 20s. I can now see the logic in those thoughts that I previously considered silly. Time has passed so quickly that we are still in the phase of speculation, trying to process everything that occurred years ago.
Okay, Time. But are we really aware of its meaning? Let’s try to dig in today.
Time in some sense is just the label of different events in the Universe. The Universe happens over and over again, and time helps in telling the difference between one moment and the other. One of the most notable features of the time is that it has direction. That is we can tell the difference between the past and the future. We really think about this as the intrinsic feature of reality. Like the past already happened, it’s in the book. The future is up for grabs. It hasn’t happened yet, and the present is where we live.
Let’s not think of time as something that “passes,” but rather, as we imagined before, as something that we simply have and lose. In this way, we will understand it better. “ Well, time could exist without an arrow.” It will take some mental discipline for us to grasp this. Even though there isn’t an intrinsic arrow in space, space nonetheless exists. Space has no unique orientation at the level of the fundamental rules of physics. In the same way, time would continue to exist in the absence of an arrow. However, there is a space arrow here on Earth. If I pick up a coffee cup and let it go, it will always fall down. The up and down can be distinguished clearly. This is not because “downness” is embedded in the laws of Physics, rather, it’s because we reside in the vicinity of an influential object, the Earth. The arrow of time is exactly the same. In our everyday lives perceive the arrow of time because we live in the aftermath of an influential event: The Big Bang.
Big Bang:
The explosion originated from a singularity, which is a point in space-time where the known laws of physics are not applicable. This would result in the co-creation of matter, time, and space. Even if the concept of time has changed significantly over classical physics’ history, these differences may be even more pronounced when compared to the actions and processes that quantum mechanics discloses to us through its particle experiments. Our perception of the past, present, and future is not always clear in the subatomic world and occasionally seems to be only a fantasy.
According to a certain agreement, time is the series of occurrences or variations that are seen by the senses and then processed by the brain, giving rise to the concepts of the past, present, and future. These results enable us to envision and forecast the direct evolution of the states of the surrounding matter. In fact, would we even perceive time passing if nothing changed, not even ourselves, and everything stayed the same as it is right now, as is sometimes the case in science fiction films when time “freezes”? How would we be able to tell the past from the future? Is there even a history and future like that?
That gets us into the realm of the concept of “Entropy.”
ENTROPY:
It tells how messy, disorganized, and random a system is. There is a natural tendency for things to go from lower entropy to higher entropy (2nd Law of Thermodynamics).
Why is the world ever low entropy to begin with? Why was the world lower entropy yesterday than it is today?
This is because the entropy was lower yesterday than it is today. The chain of reasoning goes back 14 billion years (13.8) to the Big Bang. to the origin of the observable universes. “A very hot dense state, very low entropy, and the entropy is increasing ever since.” : called Past Hypothesis.
“We literally owe life to the fact that entropy is increasing”. If the entropy is not increasing? It means nothing interesting is taking place. Without entropy increasing there’s no memory of the past, there’s no causal effect we have on the future. We’d just be in ‘thermal equilibrium’. Everything would be the same everywhere.
Conclusion:
We know about our Universe’s past. And we know about the present. The Scientific observations of the Universe expanding at an accelerated rate. But what about the Future? Do we know how our Universe is going to end? Cosmologists have 3 answers to it.
Imagine 2 objects representing galaxies. A short tight rubber band is holding them together (that’s gravity), meanwhile, 2 hooks are pulling them apart (that’s the repulsive force stretching the system). We have something that approximates a real universe by repeating the system. The final consequence of these two forces will dictate how the cosmos unfolds.
BIG FREEZE: When the repulsive force is just strong enough to stretch the rubber band until it loses its elasticity. The expansion wouldn’t be accelerated anymore but the universe keeps on expanding. Clusters of galaxies are separated until they dissolve into lonely objects. The light they emit would be red-shifted with very low faint energies. The gas emanating from it becomes thinner and not enough to create any new star. The Universe becomes darker and colder approaching a frozen state also called the Big Chill or the Heat Death.
BIG RIP: What if the repulsive force is so strong that it stretches the rubber band past its elastic limit? This is the case when the Universe starts to expand with acceleration. It not only overcomes the Gravitational force that tears the galaxies apart but also the Strong and Weak Electromagnetic force that binds the atom and nucleus together. This tears apart all the matter into pieces.
Even atoms and subatomic particles will be destroyed. That’s the big rip.BIG CRUNCH: This represents a potential future in which gravity prevails. This stops the universe’s expansion and then turns it back on itself. Planets and galaxies are speeding toward one another. The pull would get stronger as they clumped together. As the room gets increasingly confined, the temperature begins to rise. This continues until the subatomic particle and atom are forced to collide. The outcome will be a very hot, dense, and compact Universe, similar to a state that existed before the Big Bang.
Which of the scenarios will win? The answer depends on the exact shape of the Universe. The amount of energy it holds, and changes in expansion rate. As of now, our observation suggests that we’re heading for a Big Freeze. But we still have the 10th to 100th power year before the chill sets in.
Could this tiny point of matter explode into another Big Bang? Could the Universe expand and contract over and over again repeating its entire history?
Let’s revisit it :-)
Thank you :-)
