Does a certainty in the position imply infinite variation in speed?

Click For Summary
SUMMARY

The discussion centers on the implications of the Heisenberg Uncertainty Principle, specifically how increased precision in measuring a particle's position (Δx approaching 0) leads to an infinite uncertainty in momentum (Δρ approaching infinity). Participants explore the relationship between position and velocity, concluding that knowing an electron's position does not restrict its possible velocities, which can range from 0 to the speed of light (c). The conversation highlights the importance of understanding standard deviation in measurements and the complexities involved in discussing quantum mechanics with laypeople.

PREREQUISITES
  • Understanding of the Heisenberg Uncertainty Principle
  • Familiarity with quantum mechanics terminology
  • Knowledge of standard deviation in statistical measurements
  • Basic concepts of particle physics, including mass and velocity
NEXT STEPS
  • Research the implications of the Heisenberg Uncertainty Principle in quantum mechanics
  • Study the relationship between position and momentum in quantum particles
  • Explore the concept of standard deviation and its application in physics measurements
  • Investigate the role of forces in particle behavior at quantum scales
USEFUL FOR

Students of physics, quantum mechanics enthusiasts, and professionals in scientific research who seek to deepen their understanding of the Heisenberg Uncertainty Principle and its implications on particle behavior.

Giuseppino32
Messages
4
Reaction score
0
TL;DR
As position uncertainty decreases, the uncertainty in momentum and velocity increases, potentially approaching the speed of light. While Δv can be large, it doesn’t imply any arbitrary velocity from 0 to 𝑐; it's probabilistic and constrained.
I would like to know if this thought makes any sence or if i'm missing something

Heisenberg principle states that: ΔxΔρ ≥ ħ/2Δρ ≥ ħ /2Δx
If we consider a scenario where we increase the precision of our measurement of position, we have Δx ⇒ 0 the principle implies:
Δρ ≥ ħ/2Δx → Δρ ⇒ ∞

Assuming that any of that makes any sense, If we consider the maximum possible speed in the universe, c (the speed of light, approximately 3×10⁸m/s) the minimum possible speed as 0, and assume the mass of the particle remains constant, then the uncertainty in velocity Δv is given by: Δρ = 3.10⁸ - 0 = 3.10⁸ m/s

This illustrates that as the uncertainty in position decreases, the uncertainty in momentum—and thus velocity—can increase significantly, potentially approaching the speed of light.
Does that makes physical sense? Lets say we know where an electron e⁻ is in space so if its mass is constant 9.1093837 × 10-31 kilograms. If we find out its position does it mean it could have any value from 0 to the speed of light, in any direction, without the necessity of a force?
 
Physics news on Phys.org
How doe we "know" this very defined location?? Likely there are some nontrivial "forces" involved.. The Heisenberg uncertainty limit is difficult to circumvent.
 
Giuseppino32 said:
the precision of our measurement of position

##\Delta x## is not the precision of our measurement, it's standard deviation. It's sad that a lot of physicists forget about that when they talko to laypeople.


Or even physics students. Like this one professor at my alma mater, who was known for being very nitpicky and rude towards students, and making a lot of mistakes herself at the same time. But you know, she is doing experimental physics, so she does not have to remember all the theoretical details. Or even how linear function works. Oh well. Sorry for that off-topic.
 
Last edited:
weirdoguy said:
##\Delta x## is not the precision of our measurement, it's standard deviation. It's sad that a lot of physicists forget about that when they talko to laypeople.


Or even physics students. Like this one professor at my alma mater, who was known for being very nitpicky and rude towards students, and making a lot of mistakes herself at the same time. But you know, she is doing experimental physics, so she does not have to remember all the theoretical details. Or even how linear function works. Oh well. Sorry for that off-topic.
Oh, thank you for this insightful response. It is a bit weird because it is almost like it still follows the exact same logic, although not necessarily they carry the same meaning, which still holds the discussion the same way. It's really sad that what motivates most people in this forum is making corrections rather than discussing the question. Not your case, though—again, thank you for this wonderful piece of information you just provided us. Keep doing the extraordinary work
 
Well, my problem is that writing longer responses in english takes me way too much time, so usually my responses are quite short. But I'm known for writing walls of texts on polish forums o0)

And with your question, what I wrote is quite an important thing, and with that in mind you should reconsider whether your question still makes sense. Sometimes such thing changes everything, so there is no point in analysing what someone wrote after wrong assumption.
 

Similar threads

  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 11 ·
Replies
11
Views
2K
  • · Replies 11 ·
Replies
11
Views
2K
  • · Replies 36 ·
2
Replies
36
Views
6K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 14 ·
Replies
14
Views
2K