h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Are eletrical fields real or not?

Are they actual real things, which have certain properties, or are they just ways of predicting and describing behaviour of other real things, ie particles?

blub-blub

They are real, measurable things.


Ste

So real, as in independant of the particles they affect, real in their own right?

Does this mean they can be measured of themselves, without having a particle being affected by them? I f so how?

Thanks for responding

blub-blub

I assume you refer to electromagnetic fields.

They are very real, and independent of particles, as they will exist across a vacuum.

However, you can't measure them without affecting particles, because what you are measuring is the change in movement of particles affected by the field. In fact, you can't measure anything without disturbing particles - the measuring instrument has particles that must be disturbed in order to make the measurement. It's classic quantum mechanics, as stated by Heisenberg.

B

Pretty much no, but then you can't detect a particle without having it affect another particle or field.

Simulpost. Just listen to MB, he was a lot clearer.

So, how can you know that the field is an actual, real 'thing' as it were? As opposed to being an abstract set of rules used to describe behaviour of particles in certain situations?

Sorry, its just I find this quite intresting.

Thanks again for your help.

b-b

Traveller in Time confused
"And I thought I was listening to the radio . . . "

In one way you're right, you can't. But then the converse is true. Are any of the particles real? Or are they just manifestations of the field? Which one is actually real, the field or the particle, or both?

"So, how can you know that the field is an actual, real 'thing' as it were? As opposed to being an abstract set of rules used to describe behaviour of particles in certain situations?"

It's a fair question, and if you're going to be pedantic about it, you can't. And nearly all of physics, classical and modern, falls into the same boat. Science, after all, is just the creation of acceptable theories to explain what happens around us.

Unless. If you take as your actual 'thing' or definition as the action that it has on said particles. In other words: gravity could be described as 'not a real thing'. But our tangibility is to say that gravity is 'a force that mutually attracts two bodies of matter, proportional to their mass and the reciprocal of the distance between them'. I hope this is a statement that would satisfy most scientists, but you'll note it says nothing about gravity as an entity, only its effect on other things. Do you see what I'm getting at?

B

I understand. Unfortunately, that's what I find intresting. ho-hum

I very much appericiate your help.

"If you take as your actual 'thing' or definition as the action that it has on said particles"

So let us treat this as the definition of a 'thing', I think its a good one. Do eletrical fields cause affect particles? Or are they descriptions, labels if you like, of behaviour of particles, caused by something else? I've worded that horribly, sorry. hummmm. Do particles behave as they do because of, say, their relative position to a magnet, and then us humans come along and find patterns in these behaviours, which we describe in a predictive 'formula' (not sure if thats an appropriate word), or does the magnet cause the actual existence of eletrical fields, which then affect particles?

Just musing really. I'm not even sure if the question is a scientific one, in which case I guess I've brought it to the wrong place!

I guess we can't really know, I just find it intresting!

b-b

Traveller in Time finally getting the question
"The answer should be no ?

Any magnetic field has its own shape, depending on the magnetic particles of the core. A static magnet has grains of alligned atoms, these grains will never allign perfect. An electromagnet has windings . . . antennas have local density and size/ shape making them unique.

Any formula we use will give an approximation of the value.

You are still talking about 'eletrical fields' are they not just 90 degrees ahead of the 'magnetic field' ? "

This is more a philosophical question than a scientific one. The same argument can be applied to anything that can't be observed through the five senses, which would include most forms of energy.

It looks to me like an extension of the old " If tree falls in a forest..." query.

I actually heard a fairly convincing answer to that question. Briefly, sound is mental (therefore personal) property, without a person there to hear it fall it dosn't make a sound.

Anyway, that's off on a tangent...

b-b

Except that the sound waves - the vibrations in the air - would still be there. It kind of depends on how you define sound.

"It kind of depends on how you define sound."

A good business deal in Peckham.

B