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Observer effect and Uncertainty principle are the same?


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4 hours ago, druS said:

Studiot, you'll have to be patient with me. Very.

I have a long way to go before I am grappling with this math. I can tell you that I need to work on inequalities.

OTOH These conversations are most definitely having an impact on my choices in study. I have a building list of topics I require to be covered that sits actually quite outside the standard study choices.

Thanks for this.

 

Dru

Start with the triangle inequality. It is the easist to understand.

Basically it says that any side of any triangle is shorter than the sum of the other two sides added together.

triangleinequ1.jpg.ab81bae1f17965749c43dc0a15a9442d.jpg

Of course if you are willing to call the second figure a triangle it gives the condition for equality.

 

This seems so obvious it should be trivial but the meaning runs deeper and pops up in suprisingly numerous guises.

It is further to go from A to C via B than to go directly.

Now imagine AC, AB and BC are vectors.

The resultant of two vectors always has smaller magnitude than the sum of the magnitudes of its components, except in the second case, when they are equal.

 

Does this make sense?

27 minutes ago, Itoero said:

Yes but those values only exist when you measure them, you can't invent those values. HUP is only visible when you measure a particle And measurements are subject to the observer effect.

The hup is a constraint. If phenomena did not change when measured/observed then there wouldn't be a constraint. When you measure the momentum of a particle then you alter it's energy, you change the phenomenon….But if there was no observer effect then you could measure  the momentum without altering its energy and without changing the phenomenon. If there was no measurement/observer effect then particles don't know they are measured and you could measure momentum and position as precise as possible. Without measurement/observer effect, measuring doesn't alter the particle so you can repeat the measurements.

 

Please explain to me how your measurement changed the measureand in my example where you sit and wait, doing nothing at all (no measuring) until the light arrives, by which time the event you are measuring is over.

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When you measure the momentum, for example, you interact with its energy so you change the phenomenon.   Yes but you can't know position/momentum without measuring them.  Ok but thi

No. The observer effect is about how our measurements affect what we are trying to measure. It can apply to almost anything (for example, putting a voltmeter across a circuit changes the behaviour of

Like when you use detectors in a double slit experiment. Those detectors detect photons and in doing so, they stop the wave. (observing changes the phenomenon) Physics is what we say of the unive

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4 hours ago, Eise said:

That is your error. HUP says that momentum and position together are not precise, not just that we cannot measure them precise.

HUP would not exist if there was no observer effect. Without observer effect measuring a particle doesn't alter the particle and you could measure momentum and position repeatedly.

Without observer effect you would not destroy a photon by detecting it...the HUP would then not exist.

HUP and observer effect are ways we deal with reality.

4 hours ago, studiot said:

 

Please explain to me how your measurement changed the measureand in my example where you sit and wait, doing nothing at all (no measuring) until the light arrives, by which time the event you are measuring is over.

How do you react to my explanation?

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1 hour ago, Itoero said:

HUP would not exist if there was no observer effect.

Nonsense. It has nothing to do with the observer effect. It is a characteristic of the things being measured, not the measurement.

1 hour ago, Itoero said:

Without observer effect measuring a particle doesn't alter the particle and you could measure momentum and position repeatedly.

That has nothing to do with the HUP.

 

Please stop repeating this ignorant nonsense. Go and learn about this stuff before you embarrass yourself further.

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10 hours ago, Itoero said:

HUP would not exist if there was no observer effect. Without observer effect measuring a particle doesn't alter the particle and you could measure momentum and position repeatedly.

Did somebody already said this is nonsense? Oh, I see, Strange already did. Listen, it is obvious to us all that you lack the most elementary understanding of QM, and still you go on spouting wrong ideas. You are a victim of your tendency to make concepts vaguer than they are in science and philosophy, replacing real understanding with a feeling of understanding. You throw different meanings of concepts in one concept, like you did with scattering, Doppler effect, 'theory', etc. Nothing is gained by that.

10 hours ago, Itoero said:

Without observer effect you would not destroy a photon by detecting it...the HUP would then not exist.

What a nonsense again. Studiot told you why, and you gave no explanation of why you viewpoint would be correct. You also gave no explanation of the band spread in radio waves:

22 hours ago, Eise said:

Explain to us how you, at least principally, could overcome the limits of frequency spread in wave mechanics due to Fourier transformation. (Do not forget, the uncertainty principle is valid for any wave phenomenon, not just QM).

These questions might help you in answering the question:

  • what is the exact frequency of a wave pulse of 2 seconds?
  • what is the exact position of a wave pulse of 2 seconds?
  • what is the consequence of this, given that quantum particles have wave character?

Remember: the observer effect is based on the fact that measurement always implies a causal relationship, and understanding this causal relationship might help in lessening the effect, or in some situations compensate for it by calculating the effect and subtracting it. The HUP can principally not be removed from the measurement, because it is not due to the measurement. E.g. one can give a pretty well estimation of the size of the hydrogen atom based on the fact that the HUP does not allow for an energy state being exactly 0, which would mean you have exact information about its energy. Now do you think that the energy of the electron in hydrogen, and therefore the size of its orbital, is dependent on our measurement? How does the spectrum of hydrogen depend on our measuring of the light, that already appeared independent of our measuring (ups, just realise this is a similar question Studiot asked).

As suggestion to the administrators: I would move every posting von Itoero immediately into 'Speculations' when it is in a science topic and is wrong or highly speculative. Just think about people like druS, who might not know who is talking nonsense, and who is an expert.

 

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13 hours ago, Itoero said:

HUP would not exist if there was no observer effect. Without observer effect measuring a particle doesn't alter the particle and you could measure momentum and position repeatedly.

HUP isn't about altering the particle.  It's inherent uncertainty in the variables in question. You can't say you've altered something of you don't know what value you started with.

Without the observer effect you would still have the uncertainty described by the HUP. 

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Without observer effect you would not destroy a photon by detecting it...the HUP would then not exist.

HUP does not depend on the existence of photons

 

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This thread seems to have stalled,

I wonder if this is due to a basic misunderstanding of the Observer effect, perhaps paying too much attentionand too literal attention to a poor Wikipedia article on the subject.

So I have stated a new thread for the express purpose of exploring the vagaries of the Observer effect.

 

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In quantum mechanics, the uncertainty principle (also known as Heisenberg's uncertainty principle) is any of a variety of mathematical inequalities asserting a fundamental limit to the precision with which certain pairs of physical properties of a particle, known as complementary variables or canonically conjugate variables such as position x and momentum p, can be known. Because measuring those physical properties  change the particle.

17 hours ago, Strange said:

Nonsense. It has nothing to do with the observer effect. It is a characteristic of the things being measured, not the measurement.

The uncertainty is a relation of measured properties. How can the observer effect be unrelated? 

 

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23 minutes ago, Itoero said:

In quantum mechanics, the uncertainty principle (also known as Heisenberg's uncertainty principle) is any of a variety of mathematical inequalities asserting a fundamental limit to the precision with which certain pairs of physical properties of a particle, known as complementary variables or canonically conjugate variables such as position x and momentum p, can be known. Because measuring those physical properties  change the particle.

The uncertainty is a relation of measured properties. How can the observer effect be unrelated? 

 

No. The uncertainty is inherent to the system, whether or not you have done a measurement.

It tells you, for instance, that a particle in a box can never be at rest, because you know the particle is confined to a certain region, which gives a limit to the uncertainty in the position, and therefore there is an uncertainty in the momentum, i.e. you cannot say it is at rest.

No measurement has taken place.

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53 minutes ago, Itoero said:

In quantum mechanics, the uncertainty principle (also known as Heisenberg's uncertainty principle) is any of a variety of mathematical inequalities asserting a fundamental limit to the precision with which certain pairs of physical properties of a particle, known as complementary variables or canonically conjugate variables such as position x and momentum p, can be known.

Yes.

54 minutes ago, Itoero said:

Because measuring those physical properties  change the particle.

No.

 

The relationship between the uncertainty of position and momentum is inherent. It is not caused be by the measurement. Nothing to do with the observer effect. 

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13 minutes ago, swansont said:

No. The uncertainty is inherent to the system, whether or not you have done a measurement.

It tells you, for instance, that a particle in a box can never be at rest, because you know the particle is confined to a certain region, which gives a limit to the uncertainty in the position, and therefore there is an uncertainty in the momentum, i.e. you cannot say it is at rest.

No measurement has taken place.

Actually there was a measurement. The box can be considered to be a measuring device. By placing a particle in a box you change the uncertainty/probability.

The observer effect is the theory that simply observing a situation or phenomenon necessarily changes that phenomenon. This phenomenon can be anything.

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Indeed so.

1 hour ago, Itoero said:

In quantum mechanics, the uncertainty principle (also known as Heisenberg's uncertainty principle) is any of a variety of mathematical inequalities asserting a fundamental limit to the precision with which certain pairs of physical properties of a particle, known as complementary variables or canonically conjugate variables such as position x and momentum p, can be known.

Indeed so.

The product (it must be a product) variables have the dimensions ML2T-1 so it can easily be seen that

momentum x position = MLT-1 x L

energy x time = ML2T-2 x T

satisfy this.

What you have not understood is that it is only such pairs of variables that come unde the HUP>

Measuring or calculating other properties do not.

1 hour ago, Itoero said:

Because measuring those physical properties  change the particle.

 

The measuring process may or may not change the particle, but any such change is additional to the HUP .

1 hour ago, Itoero said:

The uncertainty is a relation of measured properties

 

No the HUP also applies to calculated theoretical values, where not only is no measurement ever made, but the particle may not actually ever exist at all.

 

 

It is so disappointing to have received a big fat raspberry to my attempts to help.

 

 

Edited by studiot
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19 minutes ago, Strange said:

No.

When you measure the momentum, for example, you interact with its energy so you change the phenomenon.

 

19 minutes ago, Strange said:

The relationship between the uncertainty of position and momentum is inherent. It is not caused be by the measurement. Nothing to do with the observer effect. 

Yes but you can't know position/momentum without measuring them. 

11 minutes ago, studiot said:

 

No the HUP also applies to calculated theoretical values, where not only is no measurement ever made, but the particle may not actually ever exist at all.

Ok but this concerns mathematical logic.

 

16 minutes ago, studiot said:

 

The measuring process may or may not change the particle, but any such change is additional to the HUP .

Can you measure something without changing it? What does it mean 'additional to HUP'?

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4 hours ago, studiot said:

 

It is so disappointing to have received a big fat raspberry to my attempts to help.

I often don't see and read stuff, but thanks for that comment...my reputation keeps dropping.

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4 hours ago, Itoero said:

Can you measure something without changing it? What does it mean 'additional to HUP'?

It means that the HUP is not caused by the measurement, but the observer effect could cause changes in the measured value.

 

3 minutes ago, Itoero said:

I often don't see and read stuff, but thanks for that comment...my reputation keeps dropping.

Maybe your reputation wouldn't keep dropping if you were willing to learn, instead of displaying your ignorance so confidently.

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13 hours ago, Itoero said:

I often don't see and read stuff, but thanks for that comment...my reputation keeps dropping.

 

Not from me, you didn't.

In fact I gave you an upvote for a good question in another thread two days ago.

I have also reversed the negative vote here with a +1 to encourage you to read 'stuff' and answer sensibly as you have just done.

Now to answer your specific responses

18 hours ago, Itoero said:

1) When you measure the momentum, for example, you interact with its energy so you change the phenomenon.

 

2) Yes but you can't know position/momentum without measuring them. 

3) Ok but this concerns mathematical logic.

 

4) Can you measure something without changing it? What does it mean 'additional to HUP'?

 

1) I don't know of any way to measure momentum without affecting the moving object. However affecting it  may be part of the experiment, for instance when objects collide observing the resulting velocities and directions of the (perhaps new or combined) bodies allows back calculation to what the momentum was at the point of impact.

So for bulk objects such as a bullet fired into a block of wood, observer technique and error so far outweighs the HUP we can ignore it.

But for sub atomic particles impacting singly (especially if one is destroyed) the HUP becomes significant as well as observer error.

2) In a Hadron collider we know the position of the target to incredible precision, since we put it there. But yes the spread of momenta is then wide.

3) Thank you for that acknowledgement. So for instance an example calculation in a textbook,  is subject to Heisenberg Uncertainty, which cannot be due to any measurement technique.

4) Yes, there are at least two methods of measuring some properties without changing them.
This is why I started that spin of thread concerning Wikipedia, which contains plain incorrect statements about this.

One of the Wiki examples concerns measuring the voltae and/or current in an electric circuit.
The example states, quite correctly, that if you connect up any voltmeter or ammeter you will get an incorrect reading due to inherent imperfections of the instruments.
There is considerable theory available as to the significance of these errors.
What is does not say is that if you choose another way to measure - called a null method - you can avoid these errors.
For example you can use a nulling potentiometer to balance the voltage.

Another method of measurement that does not change the (in this case position)  is embodied in Eddington's famous experiment to verify General Relativity.
He observed light that was bent round the Sun by gravity to observe a star that should otherwise have been hidden from view because the star's position was behind the Sun.

This is a case of observation/ no observation not changing the star's position.

I expect there are other go/nogo situations that could be thought of.

 

So do you not think conversation and cooperation is better and more productive for all concerned than ignoring ?

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20 hours ago, Itoero said:

When you measure the momentum, for example, you interact with its energy so you change the phenomenon.

 

Yes but you can't know position/momentum without measuring them. 

Ok but this concerns mathematical logic.

 

Can you measure something without changing it? What does it mean 'additional to HUP'?

!

Moderator Note

You know the drill by now when you keep insisting with waving hands rather providing evidence and reasoning for your assertions and how they apply to the topic. Soapboxing is against the rules. 

You need more rigor and study on this one to keep it open. 

 
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On 3/13/2019 at 2:34 AM, studiot said:

Start with the triangle inequality. It is the easist to understand.

Basically it says that any side of any triangle is shorter than the sum of the other two sides added together.

triangleinequ1.jpg.ab81bae1f17965749c43dc0a15a9442d.jpg

Of course if you are willing to call the second figure a triangle it gives the condition for equality.

 

This seems so obvious it should be trivial but the meaning runs deeper and pops up in suprisingly numerous guises.

It is further to go from A to C via B than to go directly.

Now imagine AC, AB and BC are vectors.

The resultant of two vectors always has smaller magnitude than the sum of the magnitudes of its components, except in the second case, when they are equal.

 

Does this make sense?

 

Please explain to me how your measurement changed the measureand in my example where you sit and wait, doing nothing at all (no measuring) until the light arrives, by which time the event you are measuring is over.

 

Studio, apologies but I'm busy in study at the moment. Thanks for your insight. As usual, will come back to this as time permits.

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On 3/13/2019 at 10:07 PM, Strange said:
On 3/13/2019 at 10:04 PM, Itoero said:

I often don't see and read stuff, but thanks for that comment...my reputation keeps dropping.

Maybe your reputation wouldn't keep dropping if you were willing to learn, instead of displaying your ignorance so confidently.

Or read books...

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1 hour ago, Itoero said:

In experimental physics uncertainty relations are based on experimental data which are subject to the observer effect. 

Uncertainty, yes, but not the uncertainty relations (i.e. the HUP). They can be derived — no experiment necessary.

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1 hour ago, swansont said:

Uncertainty, yes, but not the uncertainty relations (i.e. the HUP). They can be derived — no experiment necessary.

I think perhaps itoero is confused by specifications in instruction manuals that state for instance

Voltage: +/- 1% +/- 1 digit.

The digital readout will always provide a number but the spec means the last digit of the reading is uncertain in that it may be 1 higher or 1 lower.

 

In the old days folks used to try to read greater accuracy into analog meters than was really there, estimating to 1/10 of a marked division.

But really they would get it wrong a significant proportion of the time so a reading of 1.5 could be say 1.4, 1.5, 1.6 or less often 1.3 or 1.8.

The correct proceedure was to read (estimate) to the nearest half division, which would return 1.5 in the example.

Edited by studiot
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3 hours ago, swansont said:

Uncertainty, yes, but not the uncertainty relations (i.e. the HUP). They can be derived — no experiment necessary.

Ok but from what are uncertainty relations derived in experimental physics?

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3 hours ago, Itoero said:

Ok but from what are uncertainty relations derived in experimental physics?

They are derived from QM theory. Experimental physics uses the same physics as theory.

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On ‎3‎/‎21‎/‎2019 at 4:03 PM, swansont said:

They can be derived — no experiment necessary.

How do you explain that there can be several kinds of uncertainty relations?https://en.wikipedia.org/wiki/Uncertainty_principle#Additional_uncertainty_relations How can you derive a relation if you don't know which one until you observed the system?

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