Question about Uncertainty

[Membrain]

OK, this is my second post!

 

After learning a thing or two about "probability" on my first thread, I wanted to ask about "uncertainty".

 

For starters, when it came to probabilities, it seems clear that the electron was in an uncertain place. Is this what is meant by "uncertainty" within quantum mechanics?

 

Thanks for your patience in advance.

[fredrik]

For starters, when it came to probabilities, it seems clear that the electron was in an uncertain place. Is this what is meant by "uncertainty" within quantum mechanics?

 

I assume you want an understanding without using the abstract formalism.

 

So in the general case, the intrinsic uncertainties means that some variables of the system can not be known precisely at the same time, because they have a relation.

 

There are different ways of viewing it, but here is one way to see ordinary QM.

 

First of all what IS time, and what IS energy? Wouldn't it be good to have a more proper definition of energy?

 

In QM, time coordinate and energy can not be known simultaneously because, the energy of the of the system is in fact defined in terms of the time evolution of the system. The energy states is simply taken to be the "harmonics" of the system in time so to speak. And each harmonics (single energy) is timeless.

 

Same for momentum which is the defined in the systems space evolution, so you can say that space changes generates/craves the momenum, and time evolution generates/craves energy.

 

I'm not sure what math tools you are used to, but are you aware of fourier analysis? If so, that's a mathematical analogy where you can transform information between the time domain and the frequency domain.

 

Uncertainty in space in relation to knowledge of momenum is one uncertainty, but it's a special case.

 

Another implication is the the laws of energy an momentum conservation are only mean values in QM. For example the law of energy conservation is allowed to be broken during a short instant of time due to the uncertainty between time and energy. This is how "tunneling" can occure. A particle that classical has too little energy to penetrate a barrier, can do so in QM by exploiting the uncertainty.

 

/Fredrik

[fredrik]

> After learning a thing or two about "probability" on my first thread, I wanted to ask about "uncertainty".

 

Hey Membrain, since you're a "philosopher" I'll want to add that my previous comments is pretty much a kind of standard answer, but if we are to find a new grand formalism, I think we need to go deeper, so nothing is carved in stone, which is important to keep in mind. Don't let my comment put constraints on your thinking.

 

My philosophy is that my questions will guide me to the answers. That's why I prefer to start out from very basic philosophical ground and start analysing what the heck I am really asking. The answer will never make more sense than the question.

 

The concepts of causality isn't all that obvious that one may think, yet the human mind is kind of constructed to look for causal explanations. Already here we have a broken symmetry.

 

In a certain sense our theorizing is an attempt in imposing causality in the underlying facts. I'd say that in a certain basic approach, causality is an invention to explain a set of facts. A fact is a fact without internal causal rules.

 

I think that when one works out this approach, our plain way of looking for an answer does put several symmetries on the systems from step 1.

 

This is sort of how I picture all the symmetries in physics. What I am still struggling with is the exact nature of this. I am trying to understand if the mathematical formalism of the wavefunction is the most natuarl approach. But I think I am onto the key. Once I have established this (convinced myself of it's legitimacy, I tihnk alot of things will pop out all on their own as I break the given symmetries. And if I am right the classical limit of GR is probably reached. I already did some prefiddling. But since I use the power of the legitimacy of each step in forcing constrains upon the model, the importance of making sure the approach is completely valid can not be understated in my view.

 

An alternative approach is to not bother about this, but rather just consider empirical evidence and instead try to "invent" patterns or laws to explain it. The obvious question then is, what do you have for guidance in choosing the candidates? Randomization works, but is highly inefficient. Some people tend to rely on consistent mathematical models, resembling those previously known, and see if some of them happen to fit.

 

The problem with my approach is that it may be too general, and it may give rise to many things not yet seen. So I have to figure out how to view it. I am currently considering a few different approaces where the key isn't the final model, but rather a consistent model of how to evolve the model as new, to principle, arbitrary observations are made. And most probalby (my feelin), only a few evolutions are needed to explain the typica forces we already know. But this is my task to find out... I may be be wrong. But the idea I have is pretty much clear.

 

This is just my philosophy and people may consider it baloney, and to me this is not absolute, there are several ways to skin a cat, but I think this is an efficient way for me. To sort of define my internal guide, then I just follow it and see where it takes me. Simple and not very cpu consuming either

 

/Fredrik

[fredrik]

> making sure the approach is completely valid can not be understated in my view.

 

That should be overstatated.

 

/Fredrik

[fredrik]

Since I've been trying to understand the behaviour of a yeast cells in making beer the last 3 years... I've ran into the "mystery" of life.. and I've found that the answer to the mystery of things is not in biochemistry, it is not chemistry, it is not physics... it's something more "general"... something that transcends all fields... and is commong to origin of life, and "intelligent" life and probably also to the origin of the cosmic scale universe. I don't think they are just analogous in a popular sense... I think the reason for this increase in intelligence is a common thing... I don't think we will ever grasp.. but there is something even better than grasp - growth of understanding.

 

There is an apparently very clever guy called John Sowa who has written a line that I find both clever and amusing because philosophers are often claimed to be methaphysical.

 

"For scientists, the discovery of the laws of nature is the ultimate goal of their research; but for many philosophers, the concept of law is an embarrassing metaphysical notion."

-- John Sowa, http://www.jfsowa.com/ where you may find food for thought.

 

Read the first part of his ontology, and you will get what I was trying to say about causal.

 

/Fredrik

[gib65]

fredrik,

 

I think I'm starting to see the general angle you're approaching this from. You're winning my interest. Maybe you (or I) could start a thread in the "philosophy of science" forum to get into this. You think?

[fredrik]

Yes there is alot you could discuss in this! but I still consider myself in the adaptation pahse of this forum so to speak. I'm not quite sure where I am. Also I will try to get some more individual contemplation done... my experience is that sometimes too much talk is distracting.. if you know what I mean. But I'm sure we will come back to these issues... for myself I feel inspired to do more work on my own for the moment. At the moment, only contemplation can answer my immediate questions, but I am sure that eventually I'll get more specific and may get back for opinions.

 

Not sure if that makes sense

 

/Fredrik

[swansont]

OK, this is my second post!

 

After learning a thing or two about "probability" on my first thread, I wanted to ask about "uncertainty".

 

For starters, when it came to probabilities, it seems clear that the electron was in an uncertain place. Is this what is meant by "uncertainty" within quantum mechanics?

 

Thanks for your patience in advance.

 

There are may source of uncertainty. You can have imperfect instrumentation, for example. There is always a limit to how well you can measure something imposed by your tools

 

The uncertainty in QM, is different - it's inherent. Even with the best possible instrumentation, it is impossible to measure exactly where the electron is, and know how much momentum it has.

 

The used very often is to consider how you would measure the momentum and/or position of an electron. You can scatter a photon off of it and detect the photon. But you can only figure the position if the electron to a wavelength of the photon, so to more precisely measure that, you must use a very short wavelength. But that has higher energy, and will impart more and more momentum to the electron as you use a shorter wavelength. So the more you know about the position, the less you will know about the momentum.

[gib65]

But you can only figure the position if the electron to a wavelength of the photon, so to more precisely measure that, you must use a very short wavelength. But that has higher energy, and will impart more and more momentum to the electron as you use a shorter wavelength.

 

How do we measure the electron's momentum?

[swansont]

How do we measure the electron's momentum?

 

 

Well, we know its mass, so one could place it in a magnetic field, with a dilute vapor of something that will fluoresce when the electron passes by and causes an excitation, or causes a supersaturated vapor to coelesce (cloud chamber). The radius of curvature will b give you the speed, because F = qv X B and F = mv^2/r for a circular path. If you know B and measure r, you can find v.

 

Of course, the measurement changes the momentum, but we kind of expected that.

[khenemetre]

I have a question also. Of course naturally if you measure the momentum of an electron with a form of photons, the impact of the photons changes the momentum of the electron, so if we had not measured it, it would have taken an entirely different path. But apparently even if we had some super God-like power to know where exactly an electron was without measuring it, the information still would be false (that's what I heard anyway). I have just one word for you: huh?

[Membrain]

Thanks everyone for your responses. Please pardon me for not answering each post individually, but I think I've come up with another question that gets closer to my goal:

 

Two things:

 

One, it sounds like "uncertainty" has something to do with "probability" in that since we can't accurately measure sub-atomic wave/particles we have to take a probabilistic, statistical approach which leads to scientists being "uncertain" as to what the sub-atomic particles are doing at any one time. The sub-atomic particles are not themselves "uncertain"; they have a definite existence within reality, we just can't measure them with certainty.

 

And two, since science only gives validity to things that are provable and measurable, scientists have take the extra step of saying, "Since sub-atomic particles are inherently not measurable (at least not accurately), they can be considered to be inherently indeterminate".

 

To clarify: I think scientists think that to assert a determinacy about sub-atomic particles is something that is unmeasurable, and that it is only "philosophical" to talk about it. This is apparently almost heretical in science. Saying that something is "philosophical" seems to be comparable to saying that something is non-scientific.

 

So is the close® to the truth?

[swansont]

I have a question also. Of course naturally if you measure the momentum of an electron with a form of photons, the impact of the photons changes the momentum of the electron, so if we had not measured it, it would have taken an entirely different path. But apparently even if we had some super God-like power to know where exactly an electron was without measuring it, the information still would be false (that's what I heard anyway). I have just one word for you: huh?

 

The uncertainty is inherent in the system. It's not due to the method that was used; the example of bouncing a photon off of the particle is only an example.

[swansont]

Thanks everyone for your responses. Please pardon me for not answering each post individually, but I think I've come up with another question that gets closer to my goal:

 

Two things:

 

One, it sounds like "uncertainty" has something to do with "probability" in that since we can't accurately measure sub-atomic wave/particles we have to take a probabilistic, statistical approach which leads to scientists being "uncertain" as to what the sub-atomic particles are doing at any one time. The sub-atomic particles are not themselves "uncertain"; they have a definite existence within reality, we just can't measure them with certainty.

 

No, I disagree and here's why: Take an electron or photon, for example, and send it toward a double slit. It will pass through both slits, and intefere with itself, as long as you have no device to measure it going through one particular slit. It is not true that the particle has a well-defined path that we just can't measure precisely enough. i.e. if you don't explicitly measure which path it takes, it takes both. That's not behavior consistent with the particle having a definite existence and putting the uncertainty into the measurement.

[fredrik]

> One, it sounds like "uncertainty" has something to do with "probability" in that since we can't accurately measure sub-atomic wave/particles we have to take a probabilistic, statistical approach which leads to scientists being "uncertain" as to what the sub-atomic particles are doing at any one time. The sub-atomic particles are not themselves "uncertain"; they have a definite existence within reality, we just can't measure them with certainty.

 

> science only gives validity to things that are provable and measurable

 

I don't want to discuss the definition of words here but one rarely proves something to be right in physics. More often the failure to disprove something is a passive support.

 

IMO science isn't about beein right or absolute, it's more about beeing consistent and efficient. What is beyond that is in part a matter of choice. Choices that may still be very important, but system dependent. For example My best choices most certainly isn't the same as Your best choices. Or the choices of an electron, isn't the same as the choices of a proton. The all act from their point of view.

 

I think the closest thing you get to logic in physics is something loosely "along the line" of bayesian logic that is used also in game theory. What we are trying to create is rules, that seem to work.

 

To me physics is simply about trying to predict and represent the observable world in an efficient manner and try to predict the future to the best of our capability. What is really "the best of our capability" obviously depends on our information and experience. This is they starting point of my thinking.

 

I do not quite like pulling a mathematical framework out of nowhere and start assuming things. That is more like mathematical toying that trying to understand something to me. I require at least a somewhat "sensible" philosophical foundation to the mathematical structures.

 

I am currently trying to revise the standard stuff and I am amazed how fast people skip the most important parts and all of a sudden they enter complex mathematical elaboration without knowing if they are sensible.

 

Even for me, the final result must be a clear mathematical formalism, but the formalism itself means nothing until it's clear what the heack it means. To me this is importance because I use this as guidance to evolve it.

 

I am currently working on rethinking the basics, to jump into solving equations before I have justified the equations for myself in the first place is a waste of time. Or "risky" at best.

 

/Fredrik

[Membrain]

No, I disagree and here's why: Take an electron or photon, for example, and send it toward a double slit. It will pass through both slits, and intefere with itself, as long as you have no device to measure it going through one particular slit. It is not true that the particle has a well-defined path that we just can't measure precisely enough. i.e. if you don't explicitly measure which path it takes, it takes both. That's not behavior consistent with the particle having a definite existence and putting the uncertainty into the measurement.

OK, a couple more questions:

 

I thought the particle was considered to be an un-collapsed wave, and as such behaves like a wave (which ripples through both slits and interferes with itself on he other side).

 

Doesn't a wave have a definite existence? Like a water wave?

[fredrik]

Doesn't a wave have a definite existence? Like a water wave?

 

I think it depends on the approach, but normally I would for sure say that the exact wave does not have a definite physical existence in the old fashioned sense - like a water wave of sound wave.

 

In quantum mechanics the wavefunction is not measurable.

 

Think of it as information. Is information "real" to you? I would say it's sort of real, but by it's very nature obsever dependent. That's part why one can not without some "arbitration" talk about real, because it's value depend on what you are asking. But while utterly confusing this is also the power, because my idea is that observed things, like particles and phenomena can be interpreted completely in terms of observer transformations. Interactions can be thought of as information exchange.

 

While I think information is kind of real, it's not real in the sense of physically objectively real so that everyone in the universe would agree upon the wavefunction of an electron. Or put differently, there is probably a transformation between them that defines the disagreement.

 

Are EM fields "real"? The EM field clearly depends on the frame of observation.

 

What does "real" really mean? I have a feeling it lost the meaning we used to think it had.

 

/Fredrik

[SyedAmeen]

OK, this is my second post!

 

After learning a thing or two about "probability" on my first thread, I wanted to ask about "uncertainty".

 

For starters, when it came to probabilities, it seems clear that the electron was in an uncertain place. Is this what is meant by "uncertainty" within quantum mechanics?

 

Thanks for your patience in advance.

 

jan.23.2007

 

UNCERTAINTY PROBLEM:

 

The uncertainty and wave particle duality are inter-related.

Heisenberger's and Einsteins's era,the real nature and origin of Photon was elusive.But now research had different interpretation.A photon is not one particle,but an ENTANGLED QUANTUM STATE.The faster than velocity of light particles or entities,represent Wave(Field)while a charge like e- represents particle.The photon is a two particle entangled Quantum state.So faster than c field (wave)into which particle(e-) or charge lodges become photon.

 

Photon = ignorons + charge

 

That is where uncertainty comes in and duality resides.

Now it is possible to observe OSCILLATIONS of faster than light particles,like heavey neutrinos Oscillations,and attosecond laser pules interacting with electrons to result Oscillations.

This provides opportunity to look Uncertainty and duality with a differet perspective.

My ignorons quantum field theory is pointing that possibility.

 

see links listed in view of my blog at:

 

http://www.myspace.com/syedameen

http://mywebpage.netscape.com/drsyedameen1/index.html

_________________________________________________

[SyedAmeen]

fredrik,

 

I think I'm starting to see the general angle you're approaching this from. You're winning my interest. Maybe you (or I) could start a thread in the "philosophy of science" forum to get into this. You think?

 

jan.23.2007

 

Dr.Syed Ameen's "SCIENTIFICATION THEORY",is already dealing with scine Philosophy.It has introduced the concept of "MEASURE OF REALITY",AND BASED ON LAWS OF NATURE AS ABSOLUTE TRUTH.

See links listed in viewing my blog at:

http://www.myspace.com/syedameen

[SyedAmeen]

fredrik,

 

I think I'm starting to see the general angle you're approaching this from. You're winning my interest. Maybe you (or I) could start a thread in the "philosophy of science" forum to get into this. You think?

 

jan.23.2007

 

Dr.Syed Ameen's "SCIENTIFICATION THEORY",is already dealing with science Philosophy.It has introduced the concept of "MEASURE OF REALITY",AND BASED ON LAWS OF NATURE AS ABSOLUTE TRUTH.

See links listed in viewing my blog at:

http://www.myspace.com/syedameen

[SyedAmeen]

How do we measure the electron's momentum?

 

jan.23.2007

 

If photon is a two particle entangled quantum state (ignoron quantum field theory),it becomes an entirely different scenario.

 

Photon = ignoron + e-

 

Where ignorons is a faster than velocity of light particle or entity,omnipresent in the universe

Ignoron wave(Field) and e- charge is particle.An approach to design experiments of Oscillation study is possibility

[fredrik]

Here is another short reflection:

 

Let's for the sake of elaboration consider a scenario with one observer and a black box. Now this observer has an idea that there is something very solidly real and definite in that box, it's just that he doesn't know what it is. This assumption doesn't have much physical basis does it? Anyway, he tries to interact with this black box to see how it responds. And thus he collects information about how this box responds to his manipulations/provoced interactions. And thus either grains support for his preconceived image of the nature of this box, finds that the responses he observes does not fit.

 

In this case it seems quite clear that the concept of interaction is more fundamental than ANY kind of preconceived opinion of some "reality". If anything at all is real, how can anything be more real than the interactions itself?

 

I think the more plausible thinking is that, instead of thinking that "I have incomplete information about some preconceived (well defined though "currently unknown") something", this "something" in fact only by justified as "real" in terms of what I know about it. I think reality is formed by restructuring data/information.

 

Some of the problems I see in the current models is that the observer is somehow considered as an hypothetical object, like a superobserver. But how does reality appear from the point of frame of an electron? And then I am not talking just about the fram translated to the center of mass of the electron. One must pay attention to that the electron is not a ridig body. So what does the true frame of reference of the electron look like?

 

Other issues is the treatment of spacetime... clearly spacetime is system dependent. So if your "system" is the entire galaxy, or if your system is single elementary particle, the whole appearance of the spacetime is different.

 

Also, without a blink the so called second quantization is performed, and obviously (at least IMHO) the spacetime isn't the same as before. These manipulations effectively takes use to different observer frames.

 

I guess some of the current models try to fix this but I have just started to rethink alot of things... there are two most obvious issues I've seen. So any procedure that ignores these things looses me. I think this is also related to this renormalization problems that was traditionally handled in the spirit of ad hoc techniques. Such absurb tricks should not be necessary in a consistent theory IMO.

 

/Fredrik

[swansont]

OK, a couple more questions:

 

I thought the particle was considered to be an un-collapsed wave, and as such behaves like a wave (which ripples through both slits and interferes with itself on he other side).

 

Doesn't a wave have a definite existence? Like a water wave?

 

I think you're attributing the wave function collapse to some physical properties of the electron, and including the wave function in the so-called wave-particle duality.

 

The wave function is a description of the electron, not the electron itself. The electron exhibits both classical wave and particle properties. If the electron is in some undetermined state, you "collapse the wave function" when you measure it to be in one particular state, but that state may still exhibit wave properties, e.g. you may have a superposition of the spin states, but measuring the spin, which collapses the wave function, won't necessarily preclude the electron from demonstrating interference, which is a wave property.

[swansont]

jan.23.2007

 

If photon is a two particle entangled quantum state (ignoron quantum field theory),it becomes an entirely different scenario.

 

Photon = ignoron + e-

 

Where ignorons is a faster than velocity of light particle or entity,omnipresent in the universe

Ignoron wave(Field) and e- charge is particle.An approach to design experiments of Oscillation study is possibility

 

If you have an alternative explanation for these things, please post them in "speculations"

[fredrik]

For more details on a bayesian interpretation of the wavefunction collapse see an elaboration by John Baez -http://math.ucr.edu/home/baez/bayes.html

 

In that interpretation the collapse of the wavefunction is nothing more weird than the fact that a clever poker player bases his actions based on the information what cards the opponents have as the play goes on. We simply revise our state of information as we received feedback. Anything else would be kind of ignorant. And quantum mechanics does not model the ignorance as such, because it has no limit

 

While I don't mean to compare physics with a poker game (it is not) it's an important perspective, that gives part insight, to help debunk the deterministic ideals.

 

/Fredrik