#### Buzz Bloom

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Hi Nugatory:It is restricted to particles with sufficiently slow speeds that relativistic effects can be neglected.

Thnaks for your post.

OK. I accept as a definition that that "non-relativistic (NR) QM" excludes photons. I also accept that the currently best understanding of the photon double slit phenomena is based on QED, the QFT relevant to EM.

I am now thinking of a double slit experiment with non-relativistic electrons (NREs). Given that the results of such an experiment involves EM and no relativity, would it be possible to calculate the results based on the Feynman concept being applied to an NRE which travels through all possible paths, i.e., goes through both slits, in reaching its destination? If so, would the use of the Feynman concept by definition make this approach an NR QFT and/or an NR QED? Or are QFTs and QED necessarily by definition relativistic?

ADDED

Below is a quote from atyy's post #3,

A particle in non-relativistic QM and a particle in relativistic QFT are "essentially" the same. The way one can see this is by reformulating non-relativistic QM of many identical particles as a non-relativistic QFT.

This seems to __imply__that a QFT can be either relativistic or NR. It also

__suggests__that using the Feynman concept is also excluded from QM.

What I am trying to understand here is a definitional difference between QM and QFTs. Is it by definition so that QM (1) excludes all but NR particles, and (2) excludes the Feynman concept of a particlal traveling all possible paths? If so, are there any additional definitional distinctions?

Regards,

Buzz

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