Go to Home Page
You are here
Go to Reference Section
Go to Directories Section
Go to Community Section
Go to Fun Section
Go to Science Store
Go to About PhysLink.com
Club PhysLink
   Not a member yet?
   Get Free Membership
    Remember me
   Forgot your login?
Top Destinations Menu
 Ask the ExpertsAsk the

 Physics and Astronomy Departments DirectoryUniversity

 Discussion ForumsDiscussion

 Online Chat Online

 FREE Einstein eCardsEinstein

 PhysLink.com Science eStoreScience


Chikrii Word2TeX Software

Click here for a free 2-week trial

Become a Sponsor


Which is larger - a quark or an electron?

Asked by: Ann Gartner


Another very fundamental question with a very counter-intuitive answer. We all tend to ask such questions because our mental picture of subatomic particles is plain wrong. This is because the behavior of such particles do not resemble our daily experience at all. When we try to picture an electron, it turns out we mostly think of it as a 'very small steel ball'. But in fact, it is _not_ a steel ball at all, and it resembles nothing we have 'seen'.

Here is my partly physical and partly philosophical understanding: In order to be able to talk about a 'size', you need at least two particles. The proton for example, does indeed have a size, but this is because it has internal structure -- it is made up of other particles. The same goes for the atom, it consists of electrons and a nucleus. However, if you have a truly fundamental particle at hand, there is no way you can assign a size to it.

As far as we know (see http://www.physlink.com/Education/AskExperts/ae114.cfm), electrons and quarks are fundamental particles, thus have no size. The "as far as we know" part here is important, because it might turn out that these particles do have internal structure, and are composed of other, 'more fundamental' particles. Electrons have so far resisted all attempts to find a hint of internal structure. With quarks, there is the further trouble that free quarks do not exist in nature, making experiments to probe their internal structure (if any) more difficult.

So, finally, you may ask, which is larger - a quark, or an electron? Neither has a known size, they are apparently both point particles. If they are indeed both point particles, the question does not apply. If they are not point particles, the answer is that I do not know...

Answered by: Yasar Safkan, Ph.D., Software Engineer, Noktalar A.S., Istanbul, Turkey

go to the top  

All rights reserved. © Copyright '1995-'2004 PhysLink.com