From the moment we are born, we start growing older and older, "time" flows in one direction for us. Though we might feel it accelerating if we're having a good time, or decelerating when bored, it never halts, not for a brief moment, and never goes the other way around.
Milk gets spilled, eggs scrambled, things get broken or mixed up. We never see them unspilled, unscrambled, unbroken, or unmixed in our normal daily life. They always go from an orderly state to disorder. And that's a process we call Entropy.
Does it explain time, however? Or is it simply just another tool of our creation for useful calculations and a poor attempt to describe what time does when it moves forward without really explaining any reason.
The apparent permanent increase of entropy is how we deceive ourselves in explaining time direction in the macroscopic world. Order and disorder are mere fabrications of our imagination! The universe doesn't care what we call a certain state, nor does it "think" an unscrambled egg, for example, is in an "ordered" state to start with.
Contrary to what entropy is defined to be, I'd even argue that the -one way- arrow of time, if anything, is going from the disordered, forcefully into an order of physical laws. Despite what pleases us as "ordered".
It appears to be emerging from something entirely different, completely detached from how we intuitively perceive it. No physical laws specifically prohibit an incident from happening in one direction or another, as long as no other laws affect or prevent it from doing so.
In short, it is an emergent property. Meaning, it's a built-up effect of multiple factors acting altogether to form a property for a whole (the macroscopic), that is just not there for its constituents (the microscopic).
Explained in layman's terms:The pile-up of effects from the various interacting sources and forces as we go up the hierarchy of structures, is what causes the emergence of this "time" effect, and it's what might prevent something from happening the other way around at the macroscopic scale.
Take our spilled milk for example, let's ignore for a moment that someone or something did the spilling, for the sake of simplicity, and just focus on its current state and what forces can prevent it from going back. Well, we got gravity of course, air pressure, surface tention, and of course the dissipated kinetic energy, to name a few. The point is, not a single reason you can find that itself isn't emergent. And that "pile-up" of various effects is the root cause of the apparent one way arrow of time.
The smaller the things are, however, the freer and the less inclined to be affected by such pile-up.
Physically speaking, time as we know it, disintegrates entirely as we dive deeper into the super tiny world of particles.
Those building blocks of everything, do not experience "time" per say. They are like jiggly dots, oozing with energy, just trying to be at rest. With our memory and consciousness when we look at them, interacting and doing their thing in a sequence, we think "time" is passing. But it's just passing for us.
Antimatter, which is a form of matter particles, behaves exactly as if it's moving backward in time, as Dr.Feynman puts it.
Say an Electron, for example, has its unique and distinctive properties, behaves in a very specific way, always goes in a specific direction when interacted with the same field, which makes us know this is an electron and nothing else.
Its Anti-Electron, the Positron, has all its same characteristics, except it moves in the opposite direction.
I'm trying to keep things simple for all readers, so I'll use this (not-so-accurate but gives an idea) analogy: By opposite, I don't mean opposite in your normal sense. It's as if a known rock is falling upwards, away from Earth due to its gravity instead of falling downwards. If we see that on Youtube, we'd know the video is edited to play in reverse, right?
Time, even seizes to exist the smaller we go, until it completely vanishes when we start talking about the particles of light, the photons, the smallest thing that can ever be. Zero mass!
Those pure forms of energy particles are massless, they only have momentum which gives them their energy, and time in their world is zero!
Even our -not so trusty- perception of time changes relative to speed, after all, time and speed go hand in hand. Clocks tick differently when moving at different speeds, becoming hugely more noticeable as we approach the speed of light. The famous "twins" thought experiment by Albert Einstein, shows how you wouldn't experience time the same if you are to sit in bed here on boring Earth vs whizzing around on a rocket in outer space near the speed of light. (You'd have an exhilarating time doing the latter for sure if nothing else)
The twin that stays on Earth would become much older than the one riding the rocket. 🚀 
Ps. Don't try to tell the police you were speeding to prevent aging, it doesn't work...
E² = p²c² + m²c⁴
In physics, mass and energy are interchangeably one and the same, nuclear bombs made sure to practically prove -with a bang- how mass can be converted into energy, and the Large Hadron particle accelerator in Geneva constantly creates mass from energy 24/7.
Energy and Mass, have always been manifestations of the same thing, nothing new, we were just blind before.
Similarly, space and time are interwoven. We call it "spacetime". (Spime?! 🤔)
You cannot talk about space without time, it wouldn't "exist", and vise versa.
Moreover, "mass/energy" and "space/time" are both tightly interrelated. There would be no spacetime without energy/mass and no energy/mass without spacetime.
For calculations and mathematical purposes that holds true. But we can simplify the understanding further for the purposes of this post.
We can reduce the complexity by saying time isn't necessary. You wouldn't need time to describe positions in one still shot.
It only becomes viable as a variable if you need to describe sequences. Completely meaningless if no memory or consciousness is there to follow sequences, and try to predict what WILL happen.
And mass/energy, on the other hand, IS in other words the space.
Because even where you think it's lacking, aka "empty space", it's not empty at all. It's full of energy!
Energy seems to be the likely most fundamental thing, but so far, it's not really completely clear for sure which property emerged from what, and which aspect is the more fundamental one, if not even all have emerged from something more fundamental. 🤷♂️
No matter how you look at it, you'd arrive at the conclusion that time is a concept of our imagination. An illusion!
Sure, it's affecting us from our point of view, but it's emergent. The underlying forces of nature are what creates that illusion. Time, along with what is called "entropy", are merely tools of our creation, useful for measurement. Nothing more.
To even talk about one thing happening and then another in a sequence, requires consciousness or at least a memory of some sort. Both of which to us, are a blessing but yet a curse. Both of which aren't there at what we consider the fundamental level of the universe, as far as we currently know.
Without memory, time would be meaningless!
♾ = 0 ?
It's funny and mind-boggling how the extreme opposites meet.
Being timeless means zero time but yet infinite.
Being massless, you have zero mass, but now unbound to travel at the fastest speed existence allows, practically becoming present at any particular point in no time.
Contrary to what they say, I do believe the microscopic "weird" world of particle physics is not really the weird one at all, nor is it as complicated. OUR world at these macroscopic scales is the weird one and surely is complex and deceiving.
Thank you for taking the time to read this space. And as always,
Until next time. 🙋♂️
1- Entropy | 2- The arrow of time | 3- T-Symmetry | 4- Antimatter | 5- Photons | 6- Twin Paradox | 7- Vacuum Energy | 8- Einstein field equations.
Note: The purpose of this post is to explore the concept of time in simple terms without getting into the technicalities, making it accessible to anyone without a prior background in physics.
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