The Line of Time

Time is one of the only things that we can not understand, despite it being one of the fundamentals of the universe. It is perplexing to think about it, about how time has been understood over the millenia and how woefully limited humanity is in the pursuit of a meaning for time. We ignore it constantly, and then complain that we don't have enough of it. We can measure time, we can predict what might happen over time, and we can see into the past, but we cannot go back there.

As the Loki series says, it is a so-called "Sacred Timeline". A line that cannot be branched is what we have to live with as a structure for the timeline(for now).

You can consider the timeline to be a highway. You can pick the car you travel in, you can steer yourself (like in Subway Surfers), but you cannot choose your speed, cannot accelerate, and most importantly, cannot turn back or forward. As per the limited knowledge of physics now, we know that we cannot go beyond the universal speed limit, that is c, the speed of light, without using infinite energy. There is a theory of superluminal particles (tachyons), but as they are faster than light, it is not possible for us to see them or measure them yet. However, we know that we can decelerate on this straight timeline, just by travelling at very high speeds, as verified by the general theory of relativity.

Also, the visibility is reduced by fog in this highway. The fog here is the uncertainty of the future. You can choose how bright your lights are, you can upgrade your steering capability, but you cannot stop. 

This brings in some fundamental questions. What exactly is time, and where does it begin, and where will it end?

If we consider time to be a proper straight line, then the arising of a universe and the heat death of the previous universe will have occurred on the same timeline.

Now, we bring in Sir Roger Penrose's recent theory, that proved the existence of a previous universe. So we can say, omnis universum e universum (All universes arise from pre-existing universes). Based on my limited understanding, this basically says the law of conservation of energy-matter on a universal scale. But, this brings in a host of questions. Consider, that the previous universe underwent a heat death, because heat death is the most plausible explanation for the ending of the universe. Now tell me, dear reader (in the comments), if the universe underwent heat death, how did we form from a singularity? Can there be a "mutation" of dark matter that somehow starts spontaneously forming singularities to attract everything else back in? Or the biggest black hole acts as a gravity sink for everything else in the universe and starts pulling everything in? A more acceptable answer to this question would be that universe just underwent the Big Crunch, pulling everything back in to a singularity and then exploding. But a Big Crunch-type event was actually proven wrong. Which implies, that if the current universe had a universe before it, a singularity would have formed in a different way. 

And another scenario would be if time was a circle. Heat death and the Big Bang are at diametrically opposite points on this circle. Implying that after heat death, some reversion of entropy occurs to make everything go back into a singularity. This is just my own silly hypothesis without a shred of scientific evidence, so you can take it as a sci-fi scenario.

But what has to be common among all these scenarios, I feel, is the reversal of entropy. It is visibly impossible for an open and dead universe to seemingly collapse back onto itself without some form of reversal of entropy, or an extremely large gravity sink. 

But there is another problem. If you just have a large gravity sink, you'll pull in all the matter, sure, but what about the space-time? Because, we know that space was formed only after the Big Bang, along with the matter. So, though gravity attracts matter, I don't think that the boundaries of the universe can be attracted. So, there might be dark matter mutation, or another mechanism that can somehow reverse entropy.

Going back to time now, we now see the scale of the problem. But, we do we have a chance to find out about how time is in this universe. Finding out if time is a line or a circle has huge implications. If time is a line, we know for certain that it is impossible to turn back. However if time is a circle, you can conduct research into time travel a bit more confidently. But then, for our purposes, time is limited to an extremely small arc, which makes it nearly straight. So, no research, sorry.

But seriously, finding an answer to a fundamental question is what man has to evolve towards. For us to even start thinking about time travel, we must first know the structure of time, and what exactly time is made of.

A few questions that I wish to know the answers to:

1. What determines the direction of time?

2. Why does time take only one direction? or Why doesn't time switch directions?

3. How can the universe collapse after heat death?

Now, just to be clear, all of this is my own inference of this problem. You may have your own inference as well, so you can share it in the comments.