The Universe. Orderly, Chaotic, or some of both?

Drakkith

That's not true. Quantum effects behave in a predictable fashion.

bapowell

...and chaotic behavior is perfectly deterministic.

bapowell

Not quite. It's true that the wavefunction evolves deterministically, but the act of observation causes the quantum state to reduce to one of the eigenstates of the observable unpredictably.

Drakkith

I take that to mean you can't predict what will happen with each individual detection? If so, then yes, I agree.

mkarger

You cannot predict with any accuracy the possibility of radioactive decay of a given nucleus.

Drakkith

Sure I can. It has a 50% chance of decaying within it's half life.

Edit: It occurs to me that I may be misunderstanding what you are saying. Of course we cannot predict when a single nucleus will decay. It just has a chance to.

bapowell

But even still, if we take chaotic to mean "unpredictable" as you say (and keep in mind that this is not the technical definition of chaos, which is totally predictable), then it's not really correct to say that the quantum world is "completely unpredictable." The time evolution of quantum states is fully determined by the Schroedinger equation: given an initial state, the propagator determines this state exactly at any later time. The inherent uncertainty in QM comes only from the act of measurement.

mkarger

Yeah I should have specified "at any given moment."

julcab12

>>> If you interpret the universe as quantum computer then we can only assume a order of complexity and render "Orderly, Chaotic, or some of both?" meaningless.

Depends on how you view the universe. We are pattern driven creatures.^^

NWH

I think it's extremely arrogant of us to say that the world we live in is ordered. Sure on paper the classical world is predictable, however in practice, how well can we make use of those predictions to do something truly important?

As ordered as the world might seem our lives are shaped off random events, the place we were born, the home we grew up in, the people we meet, our entire experience in this universe is based on something we can't actually predict. We don't have a choice in where we were born, we don't have the means to predict the precise time and location of the people we meet. You can spend your entire life trying to be the best person you can possibly but all it takes is one random event to turn it upside down and send you on a completely different path. Whether that's because of society or nature makes no difference, there are things in this world that are beyond your control no matter how much you think you can use maths and physics to predict it.

The bottom line is we just aren't advanced enough. You might spend ten years researching this very question and all your work could come crumbling down in an earthquake that you your self failed to predict and act upon.

That is the definition of chaos, in my opinion.*

bapowell

I would prefer to attribute events like these to an apparent lack of design or teleology of the universe, not to any purported "chaotic" character. But that's why we need to be careful with our terminology in science. NWH -- my impression is that people here are not debating with you on life's sensitivity to contingency (which is really more of a philosophical question anyway), but are more likely confused about your use of the word "chaos" which has a precise meaning in physics and mathematics.

Drakkith

Bapowell has it right. Your use of chaotic isn't anything like I'm used to seeing.

spark802

(quote) Chaos theory studies the behavior of dynamical systems that are highly sensitive to initial conditions. (endquote)

This quote is from the link below.

http://en.wikipedia.org/wiki/Chaos_theory


Dave