Eli5 Why can’t we “know” the speed and position of an electron simultaneously? Why can we only measure one of these properties at a time?

Question

This always confuses me and I’m not sure how it works. Please explain…

In: 252

Answer 1

If this helps, it’s a matter of precision that applies to everything.

Someone used a car example, so we’ll go with that. When we measure the position of a car. We probably use inches.

But if you wanted to measure the position of a car down to .00000000000001 inches EXACTLY, how would you do it? Well you’d have to hold the car perfectly still, right? Well how fast was it going? We can’t measure that because we stopped the car. Okay, now speed. Again we want down to .0000000000001 mph exactly. If you want to know exactly how fast the car is, it helps to have to put it on a test track where you know exactly where to point your radar gun.

So we have this thing where because electrons are so small and so fast, we cannot measure speed without affecting the location and we cannot measure location without affecting the speed. So at a given moment, we can know one but not the other.