On Apr 21, 2:33 pm, Brent Meeker <meeke...@dslextreme.com> wrote:
> These states can belong to more than one sequence of
> conscious experience. But the question is whether the order of the
> states in the computation is always the same as their order in any
> sequence of conscious experience in which they appear? For example, if
> there is a computation of states A, B, and C then is that a possible
> sequence in consciousness? In general there will be another, different
> computation that computes the states in the order A, C, B, so is that
> too a possible sequence in consciousness?
Hypothetical situation, assuming an objectively existing physical
universe. All of the particles in the universe kick into reverse and
start going backwards. For some reason every particle in the universe
instantaneously reverses course. And also space begins contracting
instead of expanding. Everything in the universe hits a rubberwall and
bounces back 180 degrees.
So now instead of expanding, everything is on an exact "rewind" mode,
and we're headed back to the "Big Bang".
The laws of physics work the same in both directions...if you solve
them forward in time, you can take your answers, reverse the equations
and get your starting values, right? With the possible exception of
kaon decay, but we'll leave that aside for now.
This is what they always go on about with the "arrow of time". The
laws of physics work the same forwards and backwards in time. It's not
impossible for an egg to "unscramble", it's just very very very very
very unlikely. But if it did so, no laws of physics would be broken.
And, in fact, if you wait long enough, it will eventually happen.
Okay, so everything has reversed direction. The actual reversal
process is, of course, impossible. But after everything reverses,
everything just plays out by the normal laws of physics. Only that one
instant of reversal breaks the laws of physics.
External time is still moving forward, in the same direction as
before. We didn't reverse time. We just reversed the direction of
So, now photons and neutrinos no longer shoot away from the sun -
instead now they shoot towards the sun, which when the photons and the
neutrinos and gamma rays hit helium atoms, the helium atoms split back
into individual hydrogen atoms, and absorb some energy in the process.
Again, no physical laws are broken, and time is moving forward.
Now, back on earth, everything is playing out in reverse as well. You
breath in carbon dioxide and absorb heat from your surroundings and
use the heat to break the carbon dioxide into carbon and oxygen. You
exhale the oxygen, and you turn the carbon into sugars, which you
eventually return to your digestive track where it's reconstituted
into food, which you regurgitate onto your fork and place it back onto
Okay. So, still no physical laws broken. Entropy is decreasing, but
that's not impossible, just very unlikely under normal conditions.
Now. Your brain is also working backwards. But exactly backwards from
before. Every thought that you had yesterday, you will have again
tomorrow, in reverse. You will unthink it.
My question is, what would you experience in this case? What would it
be like to live in this universe where "external" time is still going
forward, but where all particles are retracing their steps precisely?
The laws of phsyics are still working exactly as before, but because
all particle trajectories were perfectly reversed, everything is
rolling back towards the big bang.
In my opinion, we wouldn't notice any difference. We would not
experience the universe moving in reverse, we would still experience
it moving forward exactly as we do now...we would still see the
universe as expanding even though it was contracting, we would still
see the sun giving off light and energy even though it was absorbing
both. In other words, we would still see a universe with increasing
entropy even though we actually would live in a universe with
And why would that be the case? Because our mental states determine
what is the past for us and what is the future. There is no "external
arrow of time". The arrow of time is internal. The past is the past
because we remember it and because the neurons of our brains tell us
that it has already happened to us. The future is the future because
it's unknown, and because the neurons of our brains tell us that it
will happen to us soon.
If there is an external arrow of time, it is irrelevant, because as
this thought experiment shows it doesn't affect the way we perceive
time. Our internal mental state at any given instant determines what
is the future and what is the past for us.
In fact, you could run the universe forwards and backwards as many
times as you wanted like this. We would never notice anything. We
would always percieve increasing entropy. For us, time would always
move forward, never backwards.
My point being, as always, that our experience of reality is always
entirely dependent on our brain state. We can't know anything about
the universe that is not represented in the information of our brain
state at any given instant.
Forwards or backwards, it's all just particles moving around, assuming
various configurations, some of which give rise to consciousness.
Again, assuming that there actually is an external physical world. We
could, I think, apply the same idea to running a computer simulation
of a human brain in reverse where instead of computing the next state,
we compute the previous state.
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