This is the most bizarre and wrong concept ever forwarded in physics. The only reason that it has not been changed is because nobody can prove that specific quantities position.

How can somebody say that by increasing the accuracy of measurement of one observable quantity increases the uncertainty with which another conjugate quantity may be known.

I think that�s it�s a very wrong concept.

Thoughts/ Comments please
.

well, im second (IRC joke)

quote:

---

Originally posted by Dr Know:
How can somebody say that by increasing the accuracy of measurement of one observable quantity increases the uncertainty with which another conjugate quantity may be known.

---

This is a mistaken concept. The Heisenberg Uncertainty Principle states that the position and momentum of a particle can be determined, but not at the same time. Becoming more certain of one factor does not detract from the certainty of the other. It is an either/or situation. You can choose only one.

That is probably why it seemed wrong to you.

[This message has been edited by Prometheus (edited 08-16-2002).]

That�s what I said.

I understand what the theory is and know nearly everything about it and that�s why I�m now a researcher of physical science.

As Einstein said �god does not play dice with the universe�. That wraps this theory up in a ball. The position of the particle will soon enough be able to be calculated with precise mathematical formulae showing that there is no real relevance for this theory.

Classically we can easily measure these two quantities to infinite precision.

But in the Quantum Mechanical world all attempts to measure particle momentum and position breaks down.

So which Principle are we looking at, the Quantum Mechanical world or the classical world? This theory is based on the fundamental laws of quantum mechanics that have not even been proven to exist.

Also from classical point of view particles can appear in places where they have no right to be. However this does not worry me, I was just pointing it out because its another contradictory piece of the puzzle.

I wouldn�t be surprised if this theory was found erroneous tomorrow.



[This message has been edited by Dr Know (edited 08-16-2002).]

Given enough observed data for one factor, you should be able to infer the other factor.

An analogy would be videotaping a baseball pitch. A videotape basically records the position of the ball many times a second. From the position over time data you can determine how fast it was moving.

Or with a speed measurement using a radar gun you can calculate how fast the baseball is moving, and calculate it's position at any given time using that data.

But no technique can observe both properties.

That's just how I see things.

Yeah, but video cameras and radar guns don't alter the course of the baseball. Looking at subatomic particles means that you have to shoot another type of particle at it. That can affect the position and speed of the observed particle.

I think the analogy I was given was, "Finding birds in the dark by launching baseballs at them."

quote:

---

Originally posted by ThetaReactor:
Yeah, but video cameras and radar guns don't alter the course of the baseball.

---

Sure they do. In order to use the video camera and radar gun you need to add light to the situation. Once light is added it lends its energy to the object. So you are altering the course even though the alteration is negligible.

It was an anology. I'm sure there are better ones, but that was the best I could think of.

Damn nitpickers. Yeah, xenosss, you're right. My point was merely that the alteration of speed and course is much more noticeable when dealing with objects on a subatomic level.

quote:

---

Originally posted by xenosss:
Once light is added it lends its energy to the object. So you are altering the course even though the alteration is negligible.

---

Yes. Now for a sticky question: If the photon/s give any energy to the object, what does that energy loss do to the momentum and/or velocity of the photon/s?

I think you can see where this is going...Is the speed of light absolute and/or constant?

Nox

The speed of light in a vacuum is absolute and constant. The speed of light certainly does change depending on the medium through which it travels.

Actually Einstein, much to his dismay, later admitted that god does play dice with the Cosmos, and then Heisenberg actually never said you couldn't do both he said:

"The more precisely the position is determined, the less precisely the momentum is known in this instant, and vice versa."
--Heisenberg, uncertainty paper, 1927

Four of these measured properties are important for the uncertainty principle. They are the position of the electron, its momentum (which is the electron's mass times its velocity), its energy, and the time. These properties appear as variables in equations that describe the electron's motion. The uncertainty relations have to do with the measurement of these four properties; in particular, they have to do with the precision with which these properties can be measured. Up until the advent of quantum mechanics, everyone thought that the precision of any measurement was limited only by the accuracy of the instruments the experimenter used. Heisenberg showed that no matter how accurate the instruments used, quantum mechanics limits the precision when two properties are measured at the same time. These are not just any two properties but two that are represented by variables that have a special relationship in the equations. The technical term is "canonically conjugate" variables. For the moving electron, the canonically conjugate variables are in two pairs: momentum and position are one pair, and energy and time are another. Roughly speaking, the relation between momentum and position is like the relation between energy and time.

However I agree with Dr. Know in that the basic foundations of quantum mechanics are untested and unproven, that we cannot prove any of them. However they are coherent theories that tend to fit the facts that we do have.

Not that I understand the hard physics and math behind this, but I am inclined to believe people like Heisenberg, Einstein, Feynman, Oppenheimer, Fermi, and Bohr, when they say that that is how quantum mechanics works.

Linhir

"If the radiance of a thousand suns
Were to burst at once into the sky
That would be like the splendor of the Mighty one --
I am become Death,
The shatterer of Worlds."
-Hindu Spiritual, Bhagavad Gita



[This message has been edited by linhir (edited 08-28-2002).]

I�m glad that somebody actually understands what perspective I�m coming from.