If electrical charges swap

1. Dec 27, 2007

Q_Goest

If some insane diety wanted to play a trick on us by taking the negative charge on electrons and quarks and making them positive instead, and then taking all positive charges and making them negative instead, would there be any way that we could tell? Is there any measurement we could perform that would indicate that the negative and positive charges had suddenly changed?

2. Dec 27, 2007

dst

To my knowledge, no. Unless there's some strange asymmetry going on between the charges. I thought they were perfectly symmetric and hence, switching them over would change absolutely nothing. Of course, in a magnetic field there would be different effects. If all 4 'charges' were reversed then how could you tell a difference?

Last edited: Dec 27, 2007
3. Dec 27, 2007

Q_Goest

Thanks dst.
Not sure what other two charges you're refering to. Please elaborate.

4. Dec 27, 2007

dst

Magnetic poles. Hey, my knowledge doesn't go far at all so it's pure speculation from me.

5. Dec 27, 2007

TVP45

Can you state the difference(s) between the two kinds of charge other than how we write them?

6. Dec 27, 2007

Q_Goest

Thanks for chiming in TVP. I'm holding off on offering any responce on this question.

I'm assuming you see no change either? In which case, what proof would you offer?

7. Dec 27, 2007

PatPwnt

I believe you wouldn't see a difference in magnetic poles either. If you think about charges, what truly is the difference between them? Nothing besides that they are opposite. We can't really differentiate them apart otherwise. Same with north and south poles. If you reverse them both, they are still opposite and will behave the same exact way.

8. Dec 27, 2007

ranger

I wonder if we could use the Hall effect?

So if the hall voltage is proportional to the electron drift velocity and this drift velocity is in turn dependent on the electron mass...

9. Dec 28, 2007

Q_Goest

Thanks for the responces. I fully agree there shouldn't be any difference, but wanted to see if I might have missed anything. Regarding the magnetic poles, since the magnetic field is created by the moving electric charge, the magnetic poles will flip so to speak, but then since the charges are also flipped, any path taken by an electrically charged particle through this magnetic field shouldn't change, so there would be no way of knowing the two charges were switched.

Any other comments would be welcome.

10. Dec 28, 2007

My understanding is that negative and positive are just definitions that Faraday (or someone around that time - maybe Franklin) applied, so it's irrelevant which way around they are used. He could have called them apple and orange charges (or some name that wasn't already in use) and applied them any way he wanted - they're arbitrary

edit...
Come to think of it, that doesn't really answer your question. Changing the definition of negative and positive isn't quite the same as a fiendish diety popping down from heaven (or wherever they hang out) and physically changing the -ve (or apples) to +ve (or oranges), or rather switching the physical properties that -ve and +ve refer to. I think if they did change them around you would be able to tell the difference because nothing would work anymore and you and the universe probably wouldn't be here anymore, although then you couldn't really tell the difference because you would know the "before" but not the "after" as you wouldn't exist in the "after". Tricky....

Last edited: Dec 28, 2007
11. Dec 28, 2007

rbj

it's like i and -i. they both have equal claim to square to be -1. they are additive inverses of each other, otherwize they are identical in every qualitative respect. switch them around and no one could tell.

12. Dec 28, 2007

belliott4488

Isn't this just charge conjugation? I thought the Maxwell Eqs. are known to be invariant under charge conjugation, so there would be no difference in any field solutions.

13. Dec 28, 2007

Gokul43201

Staff Emeritus
Yes, there is!

The direction of emission of electrons from beta decay of spin polarized nuclei would change (i.e., Wu's Co-60 experiment).

belliott: Why should we restrict ouselves to probing EM interactions?

PS: For more on this, look for "charge conjugation" or "C-symmetry". The important thing here is that the EM interaction is invariant under charge reversal, but the weak interaction is not.

Last edited: Dec 28, 2007
14. Dec 28, 2007

MaWM

Gokul beat me to it. You *can* tell the difference. Its very subtle, be it might add up over time.

15. Dec 28, 2007

belliott4488

Thanks, gokul - C-P violation ... didn't think of that!

16. Dec 28, 2007

Q_Goest

Thanks Gokul, I was worried there might be something else to it. All the obvious stuff such as magnetic pole reversal seems fairly straightforward. I've heard of "symetry violations". Is that what this is about?

So the next thought is to change a few other fundamental forces or constants. (Our insane diety is just dying to play a dirty trick on us!)

Is there something else she could do that might prevent us from finding out that something has changed? Are there other constants of nature that he might flip such that everything goes back to normal, including “the direction of emission of electrons from beta decay of spin polarized nuclei”?

17. Dec 28, 2007

MaWM

As far as we can tell, even theoretically, if all particles were switched for their antiparticles, all charges were flipped AND time were reversed, the resulting world would be indistiguishable from our own

18. Dec 28, 2007

Gokul43201

Staff Emeritus
Last edited: Dec 28, 2007
19. Dec 28, 2007

MaWM

hmmmm when I mentioned antiparticles, I was trying to talk about parity inversion, which is the reflection of all spatial coordinates. My mistake.

20. Dec 29, 2007

Sojourner01

This is effectively a discrete symmetry question. As Gokul stated, the weak interaction isn't invariant under charge symmetry, but it is invariant under (IIRC) charge-parity symmetry. In other words, if you were to invert the charges as you suggested and switch the labels on the concepts of 'left' and 'right', there would be no perceivable difference in physical laws.