Question: how the uncertainty principle works?

[Tormod]

Originally posted by: TeleMad

The uncertainty principle applies even if we don't make a measurement.

 

And that's a very important point - thanks.

[Freethinker]

Originally posted by: TINNY

we can just say that god purposely created matter with uncertainty.

You can SAY what ever you like.

 

But no one has ever given a VALID proof for support.

 

So ramble on.

 

But don't expect anyone with a science orientation to take it seriously.

[TINNY]

FT - The point I'm trying to make is that the uncertainty does not necessarily mean there's no omniscient Being because there's a possibility that God intended it that way, or that's how God works.

[Tormod]

Originally posted by: TINNY

FT - The point I'm trying to make is that the uncertainty does not necessarily mean there's no omniscient Being because there's a possibility that God intended it that way, or that's how God works.

 

This is not a valid application of the uncertainty principle. That something is "possible" has nothing to do with quantum physics.

[Freethinker]

Originally posted by: TINNY

FT - The point I'm trying to make is that the uncertainty does not necessarily mean there's no omniscient Being because there's a possibility that God intended it that way, or that's how God works.

And YOUR missing the point of Uncertainty.

 

What your trying to claim is the some all powerful, all KNOWING entity created a system that even IT could not KNOW the specific actions of.

 

This is just like the conundrum of whether god could create a being greater than itself. If it CAN, then it is NOT all powerful, as something can be MORE powerful. If it CAN'T then it is NOT all powerful because it can't do something.

[lindagarrette]

Originally posted by: TeleMad

The uncertainty principle applies even if we don't make a measurement. For example, it's not limited to position vs. velocity: the uncertainty principle also applies to time vs. energy. That is how virtual particles can be created and why their existence is limited by the amount of energy "borrowed". Virtual particles are being created out in space where there is no one observing them, and they were being created billions of years before humans existed. Uncertainty is a fundamental part of the way nature works: it doesn't rely upon the existence of humans nor on our making measurements.

 

How do you know that? Your example doesn't make sense and what makes you think nature works through uncertainty? The laws of nature are based on cause and effect.

[TeleMad]

Lindagarrette: The laws of nature are based on cause and effect.

 

The goings on in the quantum world are not confined to cause and effect.

[Freethinker]

Originally posted by: lindagarrette

How do you know that? Your example doesn't make sense and what makes you think nature works through uncertainty? The laws of nature are based on cause and effect.

Part of Uncertainty is specificaly removed from Cause and effect.

 

Again the example of Radioactive Decay.

 

If you take a mass of a given radioactive element, we know it's decay rate, or how many particles (clicks on a giger counter) it will release during a given period. We know what the cause is. Thus you could say we know what the effect is.

 

The problem is, we CAN NOT know WHICH of the atoms will be the one to release the particle next. If it was strick "cause/ effect", it would be like a line of bottles on a shelf. We would KNOW which bottle was next in line as we pushed them off. The cause would be supplied to the known bottle and thus the effect would be a fully predictable event. Even if we set up some large pile of bottles. With enough data on the forces involved we could predict which bottle would be the next one "effected". Harder job, more calculations, but still predictable causality.

 

But Uncertainty removes the ability to have a fully predictable cause/ effect. We can offer probablities, but not factual outcome.

[Freethinker]

Originally posted by: lindagarrette

The laws of nature are based on cause and effect.

Then there are Quantum Pairs. Pairs of particles that "appear" at a completely unpredictable time/space.

[Bo]

(on virtual particles)

How do you know that? Your example doesn't make sense and what makes you think nature works through uncertainty? The laws of nature are based on cause and effect.

 

These particles that come in and out of existence give the properties of the vacuum (because even if there's nothing left, there still is something because of uncertainty). This so called vacuum energy is VERY well measured and has one of the most precise agreements with theory that we know of. (measurements of the "anomalous magnetic moment" of the electron for example agrees for 99.999999999999999% (15 of them!) with the theory.)

 

 

Bo

[Tormod]

And frankly, to put a philosophical angle on this discussion, causality may be a human construct. We see things happen and ask why, but it is not always easy to find out what happened first and if what we saw hapen was a direct conseqeuence of it. I mean, a long line of philosophers have discussed whether causality really exists.

 

Isaac Newton nailed it in physics, of course, with his "every action has a reaction" but the Scottish thinker David Hume did the same in philosophy with his "inductive" reasoning, which is based upon the assumption that people base their experiences on empirical memories and act accordingly. Thus cause and effect is something which forms the basis of our existence, and in fact almost all of our science is built upon it. We do things because we know they will lead to something else.

 

Yet we often discuss "what is time" and we tend to see time as a continous flow of events, one leading to another, whereas it has so far been impossible to separate "time" from "space". We are unable to explain what time is and prove it. While this may sound ridicilous, it does mean that we cannot necessarily prove that something happened "before" something else (time-wise), even though we "perceived" the things to happen in sequence.

 

Hume used billiard balls as an example - when the white ball hits another ball we *know* the other ball will move because of the impact. But that is the problem with empirical knowledge. We can observe and observe and say "X happens because of Y", yet there is absolutely no way to guarantee that next time you try it will still work.

 

With quantum fluctuations there is a further problem. If we look at Feyman's diagrams, particles move not only through space but also time. The path we observe is the average of all possible paths the particle could take. Some of those paths move backwards through time.

 

Cause and effect requires that we know the state of an object in the present with enough precision to calculate what will happen to it. In quantum physics this is impossible, because we cannot get a precise enough measurement of a particle without violating the uncertainty principle.

 

Causality is not only broken in the quantum world. There is increasing awareness that there is an underlying chaotic nature in many fields of science, like biology (mutations, evolution), geology (prediction of earthquakes), mathematics (it is impossible to calculate the amount of prime numbers between any two integers without actually counting them, because htey are spread in what appears to be a random way - finding a solution to this is the core of the Riemann Hypothesis) - just to mention some examples.

 

So "cause and effect" is not always a simple thing.

[Freethinker]

Originally posted by: Tormod

Yet we often discuss "what is time" and we tend to see time as a continous flow of events, one leading to another, ...

Hume used billiard balls as an example - when the white ball hits another ball we *know* the other ball will move because of the impact. But that is the problem with empirical knowledge. We can observe and observe and say "X happens because of Y", yet there is absolutely no way to guarantee that next time you try it will still work.

This also shows one of the problems with a simple cause/ effect senerio. The massive amount of potential "causes". A slight off center hit to the cue ball, drag of the table felt, air movements in the room, non-level table, imperfections of the balls/ felt/ slate...

 

On a simplistic surface level it is OK to claim that the ball was not sunk because of the wrong stroke of the cue against the cue ball. But there are so many other factors, we could include the butterfly in the Amazon.

So "cause and effect" is not always a simple thing.

Zactly!

[Tormod]

Originally posted by: Freethinker

On a simplistic surface level it is OK to claim that the ball was not sunk because of the wrong stroke of the cue against the cue ball. But there are so many other factors, we could include the butterfly in the Amazon.

 

Yes. The complexity of any system means that there are a lot of variables to consider. In a macroscopic scenario (like the pool table) we could perceivably factor in every possible thing that could happen, and give a *close to* 100% accurate prediction of what will happen when X hits Y. The uncertainty can get close to zero because we can know just about everything we need to know (ie, we can know the present state of the system). But an unsteady hand could ruin the setup - yet this is not due to the uncertainty principle but to pure chance.

 

On a quantum level the uncertainty is built in. We cannot know with 100% accuracy the present state. We cannot, thus, know both the velocity and spatial location of a particle, and therefore we can only say that "there is an Z probability that X will cause Y". We cannot know if it will happen until it does.

[Freethinker]

I think a very good explanation was given by Carl Sagan in I belive it was Demon Haunted World. He said that in the Quantum world, your car could melt down, flow out of the garage and reconstruct itself. This is a fully acceptable Quantum event. But the probablity of it happening in our life time is so extremely high that we can reject the possibility of it happening.

[TeleMad]

Freethinker: If you take a mass of a given radioactive element, we know it's decay rate, or how many particles (clicks on a giger counter) it will release during a given period.

 

No, we probably wouldn't know it's actual decay rate; decay rates aren't typically exact. And nothing guarantess that even if an exact decay rate was determined yesterday, that that value would hold - exactly - for the sample we had today. Oh Freethinker, I'm afraid that we'd probably be at least one particle off, contrary to what you asserted.

 

(See, Freethinker, if I really try to be a twit, I can act just like you.)

[Tormod]

Originally posted by: TeleMad

(See, Freethinker, if I really try to be a twit, I can act just like you.)

 

Please stop this nonsense.

[Freethinker]

Originally posted by: TeleMad

Freethinker: If you take a mass of a given radioactive element, we know it's decay rate, or how many particles (clicks on a giger counter) it will release during a given period.

 

No, we probably wouldn't know it's actual decay rate; decay rates aren't typically exact.

I see, so half lives don't exist.

And nothing guarantess that even if an exact decay rate was determined yesterday, that that value would hold - exactly - for the sample we had today.

So much for everything we thought we knew about half lives.