Positive and negative - only words used to convey opposites?

[Sorcerer]

Hi, I was recently in a discussion/arguement with a new age spiritualist, he was using quantumn physics examples to show free will and argue about spirits and weird stuff. Especially he was speaking of morality with references to positive and negative and the attributes of the electron and proton.

I argued that positive and negative are simply words to describe the electron and the proton as opposites, the descriptions could actually be switched and thus the (Maxwells) equations could be inverted and obtain the same results. I was just wondering if I was correct, because I just bluffed I knew that.

 

So anyway, if we refered to an electron as having a positive charge and a proton as having a negative charge. And we changed all the equations around respectively. Would there be any real difference?

[Strange]

No difference at all. It is just an accident of history that the electron is called negative.

Edited October 6, 2014 by Strange

[Sensei]

Electrons and other negative particles (f.e. pion-, muon-, antiproton) are turning in one direction in magnetic field, while positive particles (proton, alpha, positron, pion+, muon+ etc.) are turning in opposite direction in the same magnetic field.

 

That's why we can tell what charges have these traces in particle detector chamber:

 

Electrons move from negative electrode to positive electrode in external electric field,

Positive particles move from positive electrode to negative electrode in the same external electric field.

 

(negative electrode has abundance of electrons, while positive electrode has underflow of electrons)

 

[Sorcerer]

Electrons and other negative particles (f.e. pion-, muon-, antiproton) are turning in one direction in magnetic field, while positive particles (proton, alpha, positron, pion+, muon+ etc.) are turning in opposite direction in the same magnetic field.

 

That's why we can tell what charges have these traces in particle detector chamber:

traces 1.jpg

 

Electrons move from negative electrode to positive electrode in external electric field,

Positive particles move from positive electrode to negative electrode in the same external electric field.

 

(negative electrode has abundance of electrons, while positive electrode has underflow of electrons)

 

Yes, but if we switched the names of the electrodes and the particles, nothing would really change. Maybe they should be called clockwise and anticlockwise? But then again, who decided the clock rotates that way lol.

[studiot]

Wouldn't there be a parity difference for pseudovectors like the magnetic field (pseudo)vector if we switched signs?

I think this is what Sensei was getting at.

Edited October 6, 2014 by studiot

[Sorcerer]

Wouldn't there be a parity difference for pseudovectors like the magnetic field (pseudo)vector if we switched signs?

I think this is what Sensei was getting at.

I don't know, that's why I was asking. Do psuedo vectors have postive and negative values and are these values based on anything objective or simply their opposite positions on a number line? Because if so, they could be inverted too.

 

(without knowing what a pseudovector is or bothering to look it up)

Edited October 7, 2014 by Sorcerer

[Sorcerer]

Took me a sleep on it, but I realised that positive and negative don't commute. IE negative * negative = positive.

Athough I don't see any reference to positive or negative values in the wiki of Maxwell's equations while only vaguely understanding it.

 

So how would it effect things if we switched the signs? Would it just be alot of equations would have to be rewritten? Would this have any implications for all the theories derived from Maxwell's equations?

[ajb]

Most minus signs in physics are due to conventions. It is a historical accident that electrons are negativity charged. People studied charges in electromagnetic fields before the electron was discovered and set up conventions to decide what is positive and what is negative.

 

So, changing conventions would be perfectly okay, if confusing. For example, you could make the direction of the flow of electrons the same as the conventional current.

 

Nothing fundamental would change in the physics.

[JonG]

Most minus signs in physics are due to conventions. It is a historical accident that electrons are negativity charged. People studied charges in electromagnetic fields before the electron was discovered and set up conventions to decide what is positive and what is negative.

 

So, changing conventions would be perfectly okay, if confusing. For example, you could make the direction of the flow of electrons the same as the conventional current.

 

Nothing fundamental would change in the physics.

Wouldn't this be the case if all matter were, by some magical process, to suddenly become antimatter - there would be no fundamental change?

[Strange]

Wouldn't this be the case if all matter were, by some magical process, to suddenly become antimatter - there would be no fundamental change?

 

Maybe. Although there is a known asymmetry between matter and antimatter. http://en.wikipedia.org/wiki/CP_violation

 

And there may be more, that we don't know about to explain why the universe is mainly matter. (Or antimatter, if you prefer to call it that. )

[imatfaal]

Wouldn't this be the case if all matter were, by some magical process, to suddenly become antimatter - there would be no fundamental change?

 

There are chirality (helicity?) issues with neutrinos and the weak force - ie we could tell. I think Feynman tells a story about corresponding an alien who it is possible is antimatter based - the way to find out is to discuss the clockwise or anticlockwise nature of a nucleus under beta decay

 

xposted with strange

[Strange]

 

xposted with strange

 

Yes, but you gave a proper example rather than a vague "there are differences ..."

[swansont]

As ajb said, it's a sign convention. The fundamental physics can't be affected by the choice. But you do have to apply it to all of the physics (i.e. you couldn't just switch electrons and positrons) , otherwise there will be problems.

[JonG]

 

Maybe. Although there is a known asymmetry between matter and antimatter.

It takes me back to my student days and all that stuff about beta decay. Your post reminded me of it.

[studiot]

 

As ajb said, it's a sign convention. The fundamental physics can't be affected by the choice. But you do have to apply it to all of the physics (i.e. you couldn't just switch electrons and positrons) , otherwise there will be problems.

 

 

Wouldn't there be a parity difference for pseudovectors like the magnetic field (pseudo)vector if we switched signs?

I think this is what Sensei was getting at.

 

 

Actually I think there would be a difference as I said.

 

Remember the OP only asked about the signs of positive and negative charge.

 

This offset this change in our set of physics equations would mean changing the sign of the vector cross product.

 

Such a change would preserve the electrical equations containing pseudovectors specific to electricity but not all cross product pseudovectors are to do with electricity.

 

What about the outward normal to area or the torque pseudovector?

 

Which way would they point if we did this?

[imatfaal]

...

 

Which way would they point if we did this?

 

I think all right hand rules would become left hand rules and vice versa; but other than beta decay and a few even more abstruse examples everything works just as well as long as everything swaps over; the exact same rules and equivalences apply just all flipped.

[studiot]

Would you clasify the outward normal as right handed of left handed?

[ajb]

I think all right hand rules would become left hand rules and vice versa; but other than beta decay and a few even more abstruse examples everything works just as well as long as everything swaps over; the exact same rules and equivalences apply just all flipped.

I am quite sure this would be the case. Essentially, you will have to take care of various 'knock-on' flips in the sign conventions. Nothing in the physics would change if I decided that positrons were negatively charged and electrons were positively charged, provided I took care of all the sign changes that this requires. This is not the same as just replacing electrons with positrons everywhere.

[imatfaal]

Would you clasify the outward normal as right handed of left handed?

 

WE use the convention that inward normal is negative and outward is positive - but the outward will always be the one exterior to a closed curve/surface and vice versa

[studiot]

So let us suppose that we switched the definition of negative and positve.

 

What direction would you assign to conventional current, noting that actual charge carriers (whatever sign you assigned to them) would continue to flow in the same directions as before?

 

Edited October 7, 2014 by studiot

[Sensei]

Imagine two vertical parallel wires.

 

One wire made of Aluminum. 13 protons, and 14 neutrons per atom.

Second wire made of Antimatter Aluminum. 13 antiprotons, 14 antineutrons per atom.

 

Through first wire there are flowing electrons from "bottom" to "top". So current I is pointing from "top" to "bottom" (reverse to direction of electrons).

 

Through second wire there are flowing positrons also from "bottom" to "top".

 

What will be magnetic field lines created by these wires surrounding them, and detected by array of compasses around them.. ?

 

Think about it.

Edited October 7, 2014 by Sensei

[studiot]

 

Think about it.

 

 

If that was an answer to my question what am I supposed to think about it?

 

The direction of conventional current is not defined by the signs assigned to the charge carriers. That is another convention which we are discussing.

 

The direction of conventional current is a convention which we choose and then apply a - or + to (which reverses the direction or not) according to the sign of the carrier involved in equations involving this current.

[MigL]

So, just to be clear,have we estabilished that pos and neg are just a convention, except for some add on effects in cases that don't satisfy mirror symmetry ( chirality ) ?

Edited October 7, 2014 by MigL

[studiot]

Positive and negative are a convention or choice without doubt.

 

But remember that we not only use positive and negative to denote the two possible polarites of charge, we also use them to denote directions in space or in the abstract that are totally independent of charge polarities.

 

We have built up a complicated interlocking network of physical equations, based on the definitions we have today and all compatible with today's definitions and conventions.

 

Many of these equations depend for their signs on more than just the assignation of + or - to the electron, but also on the combined effect of these chosen signs for direction.

 

I am just exploring the implications of this.

[John Cuthber]

It is mildly amusing to consider that not only was the choice a convention, but it's arguably wrong.

At the time, it was considered that the effect of electric charge was due to the presence of, or a deficit of some "fluid" .

Well, there is a fluid of sorts, and it's practically always electrons.

However they guessed wrong and ascribed a positive charge to things with a shortage of this fluid.

They arbitrarily chose to take the case of glass rubbed with silk as their reference and they called the glass positive because they thought it had a surfeit of this "electric fluid".

They were mistaken- it has a shortage.

 

So, since conventional charge is based on a mistake, it's absurd to use it tas the basis for any spiritualist or similar mumbo-jumbo.