Are particle fields for real?

Tags:
1. Dec 18, 2015

ftr

In QFT particles are described by fields, but AFAIK these fields are mathematical since we don't measure values of fields at a particular spacetime. So what does it mean to say a higgs field exist!

I mean it is one thing to say Higgs particle exists (in LHC), but I have not seen anybody measure its field.

2. Dec 18, 2015

DuckAmuck

Fields are used to describe the behavior of particles in the current theories. But are they actually *real*? I think that is more a philosophical question.

Like when we use the quadratic formula to compute the trajectory of a ball, is "x" real?

3. Dec 18, 2015

ftr

That is the point of my question, "x" denotes position which is a physical observable, the field values are not.

4. Dec 18, 2015

DuckAmuck

Yeah, you are right about that difference. My point was more that even if it's not something readily tangible, is it real? I am not sure how to answer that.
Field theory certainly explains a lot, just like parabolas explain trajectories. So I guess they are as "real" as they need to be, for now.

5. Dec 18, 2015

DuckAmuck

It's like the probability wave of a particle. It's not an observable itself, so is it real?

6. Dec 18, 2015

ftr

QM is all about measuring probabilities of observables like position. the wavefunction generalized to fields is not.

7. Dec 18, 2015

Staff Emeritus
Just because you are ignorant of a subject doesn't mean everyone is.

The Higgs field has a value, in vacuum, of 246 GeV. This comes, ultimately, from measurements of the muon lifetime.

8. Dec 18, 2015

Mister T

Can you give us an example of a position being a physical observable? There are things that have a position, and we can observe those things. But position is something we assign to those things. So are the things real and the position not real because it was assigned?

9. Dec 19, 2015

zonde

You say that particular field is mathematical if we don't measure it's values.
Well, it's rather philosophical question what is mathematical and what is physical in some model. And that means it has to be said in such a way that practically everyone agrees to that. So I would say that something in our model is physical if it considerably reduces complexity of our model and if it does that in a unique way. It would mean that as we make our models more complex (and combine them too) we can better see what in our models should be considered physical i.e. we can only see it in time.
It means that we hope it will reduce complexity of our models of reality IMO.

10. Dec 19, 2015

Staff: Mentor

You have to go back to what a quantum field is. Here is what's going on. You model a field by a large number of blobs. You apply QM rules to each of those blobs and let the blob size go to zero. So the reality of a quantum field is the same as the reality of a QM blob. That's well known from standard QM - its interpretation dependant.

But is also needs to be said it makes no difference to the theory - just like standard QM.

Thanks
Bill

11. Dec 19, 2015

A. Neumaier

Nonmeasurability does not imply nonexistence. The universe existed long before anyone was there to measure it.

Engineers routinely measure values of the electromagnetic field though it is a quantum field whose elementary excitations are the photons. The other quantum fields and elementary particles are just analogues with slightly different equations. That's why these fields are given the same ontological status (''they exist!'') as the obviously existing e/m field, even though we can measure only more limited information related to the other fields.

Its not very different from saying that the temperature field of the earth exists at all points in the interior of the earth although we cannot measure it in most points.