Why can't smaller particles be used to detect electrons so they don't interfere with its velocity or position?

Question

I was just wondering, why don't people use something smaller than photons? After all, aren't there smaller particles? Is there some sort of principle not allowing this?

Answer 1

The point is that if you use a particle that has less impact on the electron, then it also provides less definition with regards to spatial location.

Heisenberg's uncertainty principle states that the uncertainty that you introduce into the measurement with regards to momentum, multiplied by the uncertainty remaining in the measurement with regards to position, satisfies:
(uncertainty in momentum)*(uncertainty in position) > h-bar/2

Actually, he didn't have the factor of 2, but that would be a more precise expression, based on quantum mechanics.

The point is that, no matter whether you use photons or anything else, you won't be able to beat the HUP.

Answer 2

Electron itself is such a small particle that it is difficult to get some other particle which will not affect it. And photons are not exactly particles but packets of light energy and they do affect the electron being studied.

You should read Heisenberg's uncertainty principle in detail to understand these concepts better.

Answer 3

The uncertainty in a particle's position and momentum is not caused by the measurement technique, but is a fundamental physical property. No matter how good your measurement is, the electron's position and momentum will vary randomly within a certain range. This property is exploited in some electronic devices (tunnel diode, e.g.) where electrons cross what should be a nonconducting barrier.