There has been a lot of discussion about the existence of time. I came across this book 'From Eternity to Here;The Quest for the Ultimate Theory of Time'. Its a bit dated (2010) I have no idea what his conclusions are since I've only read part of the first chapter but it looks interesting.
It’s clear that the universe evolves as time passes—the early universe was hot and dense; the current
universe is cold and dilute. But I am going to be drawing a much deeper connection. The most
mysterious thing about time is that it has a direction: the past is different from the future. That’s the
arrow of time—unlike directions in space, all of which are created pretty much equal, the universe
indisputably has a preferred orientation in time. A major theme of this book is that the arrow of time
exists because the universe evolves in a certain way.
The reason why time has a direction is because the universe is full of irreversible processes—
things that happen in one direction of time, but never the other. You can turn an egg into an omelet, as
the classic example goes, but you can’t turn an omelet into an egg. Milk disperses into coffee; fuels
undergo combustion and turn into exhaust; people are born, grow older, and die. Everywhere in
Nature we find sequences of events where one kind of event always happens before, and another kind
after; together, these define the arrow of time.
Remarkably, a single concept underlies our understanding of irreversible processes: something
called entropy, which measures the “disorderliness” of an object or conglomeration of objects.
Entropy has a stubborn tendency to increase, or at least stay constant, as time passes—that’s the
famous Second Law of Thermodynamics. 2 And the reason why entropy wants to increase is
deceptively simple: There are more ways to be disorderly than to be orderly, so (all else being
equal) an orderly arrangement will naturally tend toward increasing disorder. It’s not that hard to
scramble the egg molecules into the form of an omelet, but delicately putting them back into the
arrangement of an egg is beyond our capabilities.
The traditional story that physicists tell themselves usually stops there. But there is one absolutely
crucial ingredient that hasn’t received enough attention: If everything in the universe evolves toward
increasing disorder, it must have started out in an exquisitely ordered arrangement. This whole chain
of logic, purporting to explain why you can’t turn an omelet into an egg, apparently rests on a deep
assumption about the very beginning of the universe: It was in a state of very low entropy, very high
The arrow of time connects the early universe to something we experience literally every moment
of our lives. It’s not just breaking eggs, or other irreversible processes like mixing milk into coffee or
how an untended room tends to get messier over time. The arrow of time is the reason why time
seems to flow around us, or why (if you prefer) we seem to move through time. It’s why we
remember the past, but not the future. It’s why we evolve and metabolize and eventually die. It’s why
we believe in cause and effect, and is crucial to our notions of free will.
And it’s all because of the Big Bang.