What does 0 amplitude mean in waves and quantum physics?

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Discussion Overview

The discussion revolves around the interpretation of zero amplitude in the context of waves, particularly in light and quantum physics. Participants explore the implications of zero amplitude on the observation and existence of particles, as well as the nature of wavefunctions and probability in quantum mechanics.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant questions whether a wave being at zero amplitude means it is no longer observed at that instant.
  • Another participant explains that the modulus squared of the wave function indicates the probability density of finding a particle, suggesting that zero amplitude implies zero probability of locating the particle at that point.
  • A participant raises a concern about the interpretation of zero probability for an object, questioning if it implies the object ceases to exist at that moment.
  • It is noted that before measurement, quantum systems lack definite values, and a zero wave function in a region indicates the particle is not present there, but its exact location remains uncertain.
  • One participant argues that having a zero value at a point does not equate to zero amplitude at that time or space, emphasizing the distinction between amplitude as a complex number and its projection onto the real axis.
  • Another participant asserts that zero amplitude does indeed suggest zero probability of finding a particle at that point, questioning if this aligns with previous statements.

Areas of Agreement / Disagreement

Participants express differing interpretations of zero amplitude and its implications for observation and existence. There is no consensus on the meaning of zero amplitude in relation to the existence of particles or the nature of wavefunctions.

Contextual Notes

The discussion includes assumptions about the nature of wavefunctions and the interpretation of probability in quantum mechanics, which may vary among participants. The relationship between amplitude and probability is also debated, highlighting the complexity of these concepts.

MathewsMD
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When a wave for light or an electron is represented on a graph, it is shown with the y-axis representing amplitude. Now, these waves cross the x-axis (where amplitude=0) but what does this actually mean, for that instant? Is it that the wave is no longer observed for that instant?

Also, since all objects have their own wavefunctions, what does the concept of 0 amplitude mean? Is the object not observed for that one instant as well?

I'm new to the concept of the wave properties of matter and quantum physics as a whole, so any clarification on the above matters (and other related material, if you wish) would be greatly appreciated!

:)
 
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The modulus squared of the wave function is the probability (density) to find the particle at a point (region) in a position measurement. If the amplitude is zero, you won't find the particle at this point (region).
 
Okay. So since all objects have a wavefunction, what exactly does it mean for the object (ex. couch) to have a 0 probability?
Does it cease to exist at some infinitesimal point that we just never see?
 
MathewsMD said:
Okay. So since all objects have a wavefunction, what exactly does it mean for the object (ex. couch) to have a 0 probability?
Before you perform a measurement, quantum systems don't have a definite value for the physical quantity you measure. If the wave function is zero in some region, the particle is not in this region. But you can't say where it is with certainty. The probability to find it in a region with a large amplitude is simply higher than in a region with a low amplitude. So it is very unlikely to find the particle in the region where it's wave function has a node.
 
I think the obvious is being overlooked - just because a wave occupies a zero value at some point in time (or space) does not mean the amplitude is zero at that time (space).

Amplitude is the magnitude of a complex number. The value of the field is the projection of the complex number onto the real axis.

Claude.
 
Nevertheless it does mean that the probability of locating a particle at that point, or probability of "particle" manifesting itself into a particle if measured at that point, is zero. Isn't it?
 

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