Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Antiparticles
Name: N/A
Status: N/A
Age: N/A
Location: N/A
Country: N/A
Date: N/A


Question:
How is a photon its own antiparticle? As I understand it, the fundamental difference between matter and antimatter is the spin of the particle....



Replies:
Fundamental difference between particle and antiparticle is NOT a difference in spin. An antiparticle can be thought of as a time reversed particle. If you start with description of a charged particle and time reverse, you get a particle with opposite charge and spin ( i mean that you get description of a particle with opposite charge and spin ). But if you start with a charge neutral particle like photon, you get the same particle with opposite spin. So we say that photon is its own antiparticle. This follows only because photon does not have any kind of charge.

jasjeet s bagla


might note that neutrinos also have no charge, and it is not at the moment certain whether an antineutrino is the same as a neutrino or not. If the neutrino is its own antiparticle, then that means the neutrino must have a mass (the argument is in fact based on spin, which might be where you heard that the difference between a particle and antiparticle is in the spin). Arthur Smith


Neutrinoes do not have electric charge but they have the Leptonic charge. I used the word charge in its generalised sense. I
Sorry for not making this explicit.

jasjeet s bagla



Click here to return to the Physics Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

NEWTON AND ASK A SCIENTIST
Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory