Questions on the test that led to Many Worlds

[rrw4rusty]

Hello,

 

This concerns the test where you have a barrier with two slits cut out of it, set in front of a wall or blackboard (or something that will show hits upon it) and devices that will shoot sub-atomic particles.

 

My understanding is this: when particles are shot into the barrier with two slits, you get a wave-like pattern on the wall behind it. However, if you watch the barrier (or take measurements?) to see where the particles are going, the pattern on the wall behind it changes and you get two lines with no wave-like interference pattern.

 

There is a goofy little video that shows this test here:

The test is shown about half way through the video.

 

Hopefully I can find someone who knows the details of this test. I of course find it very hard to believe and want to find out just how deep the rabbit hole goes. Of course I’d heard of this test and the implications long ago but somehow I missed the part about the sub-atomic particles changing their patterns from wave-like to particle-like when ‘watched’.

 

My first questions are the obvious ones:

 

Do I understand correctly that the completely non-evasive and passive act of ‘watching’ or ‘measuring’ really cause a changed in how the particles acted?

 

Exactly how was the barrier ‘watched’ or ‘measured’?

 

Searching for ‘Many Worlds’ has not shed light on these… does the test have a name?

 

Any help will be greatly appreciated!

Regards,

Rusty

[Klaynos]

The experiment is called the double slit experiment, when done with light it is Young's double slit experiment.

 

Your understanding seems to be ok. This isn't a test that led to many worlds though, it is an example of wave-particle duality, which is part of quantum mechanics. May worlds is an interpretation of quantum mechanics.

 

There is no method of detecting which slit a particle has gone through without interacting with the particle in some way, so the measurement/observation is not passive.