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Q & A: Is electron-positron repulsion possible?

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Most recent answer: 04/06/2013
i have a theory if we can make or find electrons and positrons which dont anhilate each other and only repel each other meaning move away from each other and if we put them in a container from which electric current cannot escape then those particles once moved away from each other and now cant escape or are actually made to go back towards each other with the same or even greater force is it possible that energy would be produced in that container and if they dont annihilate each other and cant escape they will keep doing what idescribed for a very long long time and every time they do will the energy produced increase? and is such a thing possible? thankyou
- anser chohan (age 38)
birmingham. uk
Dear Anser,
The short answer in no, your scheme doesn't work because of two well known ideas that have been tested by many, many experiments.  The first problem is that the only force between an electron and  a positron is that of electric charge.  Since the positron has a positive charge and the electron has a negative charge they are forever doomed to attract each other.  The second problem is the first Law of Thermodynamics, which can be rewritten as 'There is no such thing as a Free Lunch', i.e. no perpetual motion machine.   So there is no way you can extract free energy forever from any scheme you can think of.   Believe me, there are thousands of people who have tried in vain.  I invite you to read the Wikipedia article on perpetual motion.


(published on 05/08/2012)

Follow-Up #1: Pauli exclusion

Putting free lunch or "violation of conservation of energy" aside, does a pair of an electron and a positron feel the "repulsive" effect from Pauli exclusion principle? How can these two fermions collide or come so close to each other without violating Pauli exclusion principle? No fermions can occupy the same position/state(is this not the case)? Why the principle does not repel them in this case?
- Anonymous
No two fermions can occupy the same state, where "state" refers to all the quantum numbers characterizing its properties. That's why two electrons can be in the same orbital state, since they can be in different spin states. The electron and positron already have some different quantum numbers, e.g. the electrical charge, so the issue doesn't even come up for them. It doesn't come up for any fermions with different names, since we don't use different names unless some property is different.

Mike W.

(published on 04/06/2013)

Follow-up on this answer.