There are four different types of time. perception time, man-made time, entropy, and physical time.
In the previous episode of Space Ponder, we pondered that gravity is not a force but rather a consequence of space-time being warped by mass. And now we shall further elaborate on this fascinating subject to understand it better.
So,
there are actually four different types of time.
1.) Perception time ie brains
Time that is constructed within our brains to make sense of the world, it wouldn't be easy to navigate the world if time wasn't linear. You may have seen birds' movements look rather odd.
Also, you may have had a hard time swatting that annoying fly - well, that's because flies perceive time much slower than we, too!
Source https://www.theguardian.com/science/2013/sep/16/time-passes-slowly-flies-study

Well, this is because birds perceive time much differently than us they'd see time in slow motion, hence why their movements look very quick and jerky. Their brains have evolved in that fast-paced animal kingdom. And insects as well such as the fly and other life. A fly actually perceives time slower in the moment and uses the extra sensory input to react in real-time situations much faster than a human can. Our actual survival mechanism is the amygdala encoding rich memories of a dangerous event, motivating us to avoid the same danger again. Time perception is a fascinating thing.
2.) Man-made time. Clocks. Time that doesn't really exist outside of mankind.
3.) Physical time. The time that is out there independent of our brains.
This is space-time, space and time are intertwined as the same thing. This is the space-time that is the cause of gravity because gravity is a consequence of mass warping, stretching, and shaping space-time and not a force. We pondered this in the previous episode and we pondered that your head is older than your toes. But why is that exactly?
Well, because your head is further away from the Earth than your toes are, there is less mass at ur head so the space-time around your head is slightly less warped; this sounds ridiculous and too bizarre to be true but space-time isn't just in space amongst the void, but it's also on Earth, too - and we walk through it every day - and it has been proven. It has been proven time and time again. One main experiment proved it via an eclipse, it's called the Eddington experiment.
4.) The second law of thermodynamics
You've most likely noticed that your house gets messy often, a never-ending cleaning process. This is the 4th type of time. Can you guess what it is? That's right. Entropy. Entropy is why there is a forward arrow of time. It is why for example an eggshell breaks, becoming disordered - high entropy, rather than it staying in its ordered state, its low entropy state. I really like to have things explained in laymen's terms so I'll do just that rather than having to understand the unnecessary complex parts.
So, the reason things tend to go towards higher entropy, a forward flow of time, is simply because there are more ways a system can be disordered rather than ordered and that is why your house gets messy often. This all originates from the big bang because, in the early universe, it was in a low entropy state; an ordered state but as soon as the universe expanded from the big bang, everything became disordered, and everything then tended to go towards a higher entropy and this is why we have a one way forward direction of time. The reason why the universe was in an ordered state, to begin with in the first place was due to the conformal phase but we'll get to that in a bit.
This ever-increasing entropy started off the universe but it is what will bring the universe to its fate. As the entropy increases, eventually, the universe will reach a thermal equilibrium state and essentially the universe will no longer have any energy to move. This is called the Big Freeze and also Heat Death, so at this point, the universe would be dead, unable to move to interact with anything to make stuff. It would be impossible for the universe to do anything in this phase. But impossible is a bold word. Here's a great example of entropy presented by Sean Carrol. Entropy increases. Complexity first increases, (slideshare.net)
Impossible is a bold word
Then we have CCC (Cosmic Cyclic Cosmology) theory by Sir Roger Penrose, a theory that might rewrite cosmology.

This strange and interesting theory states that due to the last evaporating super-massive black holes, there will be a small amount of energy left over; so-called Hawking Radiation; this Hawking Radiation is what arises a new big bang and also what had started the previous big bang and there is evidence of this in the Cosmic Microwave Background which are called Hawking Points, remnant signal from supermassive black holes from a previous aeon. This evaporation is set to occur in 10,000,000,000,000,000,000,000,000,000,000,000,000 AD.


Penrose also states that the universe will change into a Conformal Geometry phase, meaning that as the universe continues to expand, big and small will no longer have meaning, so, strangely the universe forgets its size due to the conformal geometry. So, now the universe is back at the singularity phase, back at the "beginning" so in his theory the universe had no beginning and has gone through these big bang cycles from the infinite past and will continue into the infinite future. Weird.

Eternal
This would suggest that the Universe is eternal. Penrose explains that the universe has gone through cycles like this from the infinite past and will continue to do so in the future.
Doing a wee bit of pondering this could suggest that you have already watched this video. Maybe this could explain dejavu but just a wee ponder.
It also suggests that the universe could be fractal, which has been talked about in the eternal inflation theory, which could co-exist with Roger's theory. In eternal inflation theory, it is suggested that big bangs are happening all the time, branching off like branches of a tree; so universes inside other universes, and universes inside those universes and so on so forth. This would also suggest that nothing doesn't exist. We look around, what do we see? We always, no matter where you are, even sleeping; something is always going on, there's always something there, so no things could simply not exist and merely exist as a human concept. This is rather bizarre because this would mean that a fundamental feature of the universe would be that something always has to exist.

I hope you enjoyed this, I certainly did as it is so fascinating to ponder about this very strange universe. Feel free to share your thoughts in the comment section below. Space Ponder out.