# Why do subatomic particles act the way they are?

I'm aware of the uncertainty princple but I want to know why the quantum world is uncertain. Is it just because we are hitting it with a photon? Is it still an open question? Why is that on smaller scales it is more uncertain?

malawi_glenn
Homework Helper
No it has nothing to do that we disturb the system, the uncertainty/randomness is intrinsic.

Why? Why is nature as it is? Ask God :-)

I'm aware of the uncertainty principle but I want to know why the quantum world is uncertain. Is it just because we are hitting it with a photon? Is it still an open question? Why is that on smaller scales it is more uncertain?

It is because of a wave nature of probabilities of measurements. A wave takes more place than a point so the result of successive measurements is distributed, not concentrated.

If you look at the classical mechanics, you will see the center of inertia variables R and the relative (internal) variables of any body. When you average over all influence of relative coordinates, only three coordinates R remain, as if the real body were point-like.

In QM the influence of relative coordinates dominates so you obtain an "interference" picture rather than a concentrated set of points.

malawi_glenn
Homework Helper
One should also mention the size of Plancks constant, which is really small. Quantum energies are of the order plancks constant, so when we have larger systems, these quantum "fluctuations" are so small that we can not notice them.

(I did'n twant to go into path integrals and action etc)

I would like to add that any measurement, classical or quantum, consists of many points. One point says nothing. The first thing we look for is the average of many points. in QM we see stripped interference picture, in CM we see a more concentrated set of points, like in diffraction experiment with one strong maximum. But one point says nothing, we always need a set, the more, the better. The CM picture is an inclusive one (many points averaged).

You guys kind of confused me there but I still want to know if you thnk there's a greater force at work. If maybe it's because of something else other than just measurements. What about spacetime itself at the plank scale level?

malawi_glenn
Homework Helper
String Theory etc have QM inbuilt so the nature on physics beyond Planck scale is surely quantum in our descriptions.

There are other formulations of this standard QM, like Bohm interpretation etc

You guys kind of confused me there but I still want to know if you thnk there's a greater force at work. If maybe it's because of something else other than just measurements. What about spacetime itself at the plank scale level?

"spacetime itself" consists of measurement points. In classical physics, when we use light to see the objects, the number of measurement events is enormous due to many-many photons involved. But if we go to the low intensity regime, the points are distinguishable and there is nothing between them. Of course, we can in our minds "interpolate" and "extrapolate" beyond the rare points. We think of space-time as of underlying continuum. In fact, it is always a discrete set of event points, at any scale.

malawi_glenn
Homework Helper
Do you have any reference to these statements, certainty "In fact, it is always a discrete set of event points, at any scale" ?

Do you have any reference to these statements, certainty "In fact, it is always a discrete set of event points, at any scale" ?

Yes, look at your computer screen. You see it as continuous whereas it consists of pixels. The same with your eye, the same with any device. The same is with a photo-film.

If the light intensity is low, the photo-film registers several points only. To obtain a "continuous" picture you have to expose it to very many photons. This is called the inclusive picture.

malawi_glenn
Homework Helper
I thought you was referring to space-time itself?

I thought you was referring to space-time itself?

Exactly. It is the space-time "itself". It is highly event dependent.

malawi_glenn
Homework Helper
So all the things we learn at school that space-time is continuous is crap according to you?

So all the things we learn at school that space-time is continuous is crap according to you?

Do not use such words in posts. They characterise you very badly.

You are still many things to learn. In particular, the spin foam and the string dust. You know why? Because the naive notion of the space-time does not work.

malawi_glenn
Homework Helper
I asked for references, is that bad? Do you have any section for me in a standard textbook?

Staff Emeritus
You are still many things to learn. In particular, the spin foam and the string dust. You know why? Because the naive notion of the space-time does not work.

Bob, it would probably help if you were to clearly distinguish between the present consensus view and your own research.

malawi_glenn
Homework Helper
Spin foam, and string dust... when did we have any experimental finding of such? You seem to be an über theoretician ;-)

Bob, it would probably help if you were to clearly distinguish between the present consensus view and your own research.

There is no "present consensus", there is present folklore and the physics ongoing development, just because the current state is still not satisfactory.

malawi_glenn