Atom's Place and Speed: A Curious Question

[Wilsh]

Just because one cannot know both where an atom is and how fast it is moving, does that mean that it doesn’t have a specific place and speed at any moment?

 

[DrChinese]

Welcome to PhysicForums, Wilsh!

That is a great question, and one that is the subject of ongoing debate. Many physicists interpret the HUP to say that there are experimental bounds to our knowledge of a fundamental particle (such as an electron).

There are others who say that the HUP is a "complete" representation of the quantum world, and that reality is shaped by the nature of observations we make upon it.

Ultimately, it is a matter of your interpretation. However, there are trade-offs. If you assert that there is an exact simultaneous position and momentum for a particle, you must be prepared to accept non-locality of cause and effect.

 

[HallsofIvy]

The "Bell experiment" claims to show that the "hidden variables" interpretation (that, for example, an electron really has a specific position and momentum, we just can't measure all of the variables) cannot be true.

(Oh, and while the map is not the territory, the map is a territory!)

 

[Anonym]

Welcome to PhysicForums, Wilsh!

Just because one cannot know both where an atom is and how fast it is moving

Who told you that? Just inject it into the bubble chamber and you will see it trajectory and could measure where an atom was and how fast it was moving.
I am sure that after second thought DrChinese agree with me that this will prepare you to accept locality of cause and effect.

Welcome again to PF.

My best wishes, Wilsh!

Dany.

 

[DrChinese]

(Oh, and while the map is not the territory, the map is a territory!)

I like it!

 

[ueit]

Just because one cannot know both where an atom is and how fast it is moving, does that mean that it doesn’t have a specific place and speed at any moment?

As Heisenberg himself pointed out, HUP does not apply to the past, it is only about our capacity to make predictions.

Put a point source very far away from a screen and let it emit particles for a very short period of time. Once you detect a particle at the screen you can calculate both its position and momentum with unlimited accuracy.

 

[Wilsh]

Thanks a lot guys. I'm trying to learn some things about quantum physics so I'll probably be asking more questions. Oh and some forewarning. Sorry for my ignorance I'm only a senior in high school. But I'm stoked that you guys are so helpful.