Physics Help Forum What is the Uncertainty Principle telling us?

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 May 21st 2019, 05:40 PM #1 Banned   Join Date: Nov 2016 Posts: 63 What is the Uncertainty Principle telling us? Is it saying the power of observation/measurement of a quantum object is not enough to make it a fully 3D + 1 space-time object? If something on our scale was partially fuzzy depending on how many measurements you made (at the same time) ..would you say it was a full fledged three dimensional object? No, you'd say isn't fully here.
May 21st 2019, 06:23 PM   #2

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 Originally Posted by pittsburghjoe Is it saying the power of observation/measurement of a quantum object is not enough to make it a fully 3D + 1 space-time object? If something on our scale was partially fuzzy depending on how many measurements you made (at the same time) ..would you say it was a full fledged three dimensional object? No, you'd say isn't fully here.
(Note: Any particle, such as an electron to be specific, has 6 degrees of freedom in its motion: 3 spatial and 3 momentum. So the electron actually carries 6 dimensions in phase space. It also has spin and if it's a left handed electron it also has weak hyperspin...that's 4 more dimensions. (Right handed electrons have 0 weak hyperspin.) I know this isn't what you are talking about but we have to be clear on just where these dimensions live.)

The Uncertainty Principle says nothing about experimental equipment and how well it measures. It can be best explained using the wave mechanics representation of QM.

Consider a gaussian wavefunction, or more correctly a gaussian wavepacket. (It can be shown that the maximum uncertainty in position can be got from this. The associated momentum wavefunction is a delta function so the uncertainty in the momentum is 0 and hence the uncertainty in position is a maximum.) I've played with the scale to make the wavefunction more "peaked." The blue line represents the "width at half-maximum." This is an average size of the width of the wavefunction and tells us that the particle is generally within that range. This is where the uncertainty in the position as given by the Uncertainty Principle comes from. It has nothing to do with how many dimensions that the particle lives in.

-Dan
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May 21st 2019, 06:25 PM   #3

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 Originally Posted by pittsburghjoe Is it saying the power of observation/measurement of a quantum object is not enough to make it a fully 3D + 1 space-time object? If something on our scale was partially fuzzy depending on how many measurements you made (at the same time) ..would you say it was a full fledged three dimensional object? No, you'd say isn't fully here.

-Dan
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 May 21st 2019, 06:25 PM #4 Senior Member   Join Date: Aug 2010 Posts: 434 You need to review the definition of "dimension". It isn't what you seem to think. In physics, whether classical physics, relativity, or quantum physics, we are look at "events" that happen at a point or points in three dimensional space at a given time. Any "event" is necessarily a four dimensional object. The "Uncertainty principle" simply says that we cannot assign a single point in four dimensional space-time to an event, we can only get a small set of such points. But we are still working in four dimensions. topsquark and studiot like this.
 May 21st 2019, 06:45 PM #5 Banned   Join Date: Nov 2016 Posts: 63 I'm not one to "shut up and just do the math". I want the unobservable solved in my lifetime by tricking you smart guys into thinking about it. I do assume an undiscovered dimension is at play ..maybe one that only interacts with the quantum scale. That's a nice chart, but you are ignoring the data on it ..what is causing the fuzziness to begin with? Is it related to an object in superposition?
 May 21st 2019, 06:51 PM #6 Senior Member   Join Date: Aug 2010 Posts: 434 Why do you believe "smart guys" need to be "tricked" into thinking about this? And why do you assume things rather than reading about the current theories and, most important, about the experiments that support them. topsquark likes this.
May 21st 2019, 07:27 PM   #7

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 Originally Posted by pittsburghjoe The bell hasn't been rung that a theory of Unification is available. It would have been solved by now if the the smart guys tried.
Really? I have spent some 30 years working with QFT trying to master its complexities and work my way up to String Theory. There's a lot going on there... more than you seem to think.

I have been trying to give you detailed answers to some very complicated questions at a level that a beginner would be able to understand. It has cost me a fair amount of time to answer you and now you are telling me that you really don't care about the answers you are just trying to "trick" me into thinking about things that I already know aren't true. I think I am owed much more for my efforts.

Conclusion: Don't piss off the Administrator.

Feel free to not come back.

-Dan
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Last edited by topsquark; May 21st 2019 at 07:41 PM.

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