Time flows.
Newton seemed to think so.
So did Aristotle and countless others before. Even the Buddhists,
with their cyclic time, kept believing that time was something which
went from one instant to the other, moving forward though in circles.
That, of course, changed
after Einstein. However, I think a vast number of people still have
problems coming to grips with the nature of time and how they fit in
it. Which is no wonder: humans evolved to live within time, trapped
in their 3D slice of reality, ripe with memories and longings. This
paragraph hasn't been here forever. I just wrote it. Or did I?
In the Relativity view
-any Relativity will do- time and space are just parts of one big
mash-up called “space-time.” This does not mean one just sticks
them together: it means that time and space are both the same thing
and are, in fact, interchangeable. What looks like time to one
observer will look like space to another, depending on their relative
velocities or the gravitational field they experience.
But space is just there.
It doesn't “pass.” How can we, then, be entitled to say that time
“passes”? If going from left to right is exactly the same thing
as moving from past to future, isn't it as foolish to assume the
future doesn't exist as it is to assume the tree we just passed in
the highway is no more?
Einstein leaves us no
choice but to assume our senses lie to us: time does not pass. But
then, what? Is it us who move through time?
Well, no. Saying we move
through time is a circular proposition. Moving requires time. We
cannot “move” through anything: we're just there. Even though we
can't imagine it -since we are creatures of time- there is no clock
“outside” time. There is no “frozen in time” universe with
four dimensions, through which we move. The Universe just is. It
doesn't change. It's a 4-dimensional geometric structure. Nothing
less, nothing more.
So we don't move through
time. Or space. Or anything. We're a collection of 3D slices in a 4D
sausage. How can we reconcile that with our everyday experience?
After all, I remember going to college, dating, drinking, being
dumped. I am aware of being thirty, not ten years younger, not ten
years older. What exactly is going on?
Everything is going on. I
would say “simultaneously”, but that really doesn't make sense
outside time. I am 20, 30 and 80. I am a suckling babe. All of these
are slices of the Universe. And all of them exist, just like every 2D
slice of a sausage exists. This is somewhat difficult to take in: we
are not mentally equipped to imagine all the stages of our lives
exist “at the same time”. Hopefully, a little mental experiment
will make things clearer.
Let's imagine a mad
scientist -why is it always a mad scientist?- kidnaps you and messes
with your brain. He just developed a new, revolutionary technique,
which can replace your memories with some other person's. When he's
done with you, you remember nothing of your life and everything of
theirs. You believe you are that person and are absolutely convinced
you have always been.
But how can you be sure
this didn't happen to you? How can you be sure your own memories are
real and not implanted? One may say: through a video. But the video
may be rigged. Or you could just be living in a Matrix-like virtual
reality. How can you be sure you were not created five minutes ago by
some alien civilization and then implanted with a whole life of
experiences? How can you be sure that hasn't happened 30 seconds ago?
Or 2? Or a millisecond ago?
And here's the punchline:
how many instants do you need to have existed in order to believe
you've existed for many years? Surprisingly, the answer is “just
one.” The key is the information in your brain, not the number of
years it took to get there.
Therefore, the suckling
babe and the 8-year old kid both exist, let's say “simultaneously”,
for lack of a better word to use outside time. They both think they
are the unique you, existing now. They both believe their future will
come and their past is, well, past. And they are both wrong.
This is crucial in order
to understand Quantum Immortality. But that is a subject for a
different post.
