2d

[a.nikhil]

do 2dimensional particles exist? i have heard about something called strings [sub-atomic] which they say are 2d

 

[spacelike]

(I do not know string theory, only vague concepts, so take this with a grain of salt)

 

A particle is classically supposed to be a "point particle" and in purely mathematical terms this can never be 2-dimensional because it is defined as something with zero width, height, and depth. So in classical physics there are no 2-dimensional particles (or 3-dimensional or 1-dimensional) The 2d and 3d objects would only be due to collections of 0-dimensional point particles in a 3-dimensional space.

 

But we are starting to move away from true point particles, we realize that localizing a particle to a single infinitesimal point would be impossible.

However, even though we know this, even when discussing quantum mechanics we often still refer to them as "particles".

 

A 2-dimensional object would be a line, so yes a string could easily be called 2-dimensional. The thing is to keep in mind is what area of physics you are in and also that nobody is really certain. The best we could do is answer your question based on what theory or area of physics you are talking about at that moment.

I have answered it for classical physics (and the answer was "no"), but I can't truly say what the answer would be for string theory. Perhaps someone else on this forum is well versed in string theory and could answer your question from that perspective. But neither of them could be considered as the "definitive answer" to your question. So you may have different (conflicting) answer, depending on what regime of physics you are in.

 

But just keep in mind that the word "particle" is probably used to imply different things. In mathematics it almost always means something with 0-dimensions. But, for physics in general I would just assume the word particle refers to the physical manifestation of the fundamental object (electrons, quarks, neutrinos, etc...), which I suppose could be 2-dimensional in string theory (but again, I do not know string theory).

 

Sorry for all the editing.

Edited September 7, 2011 by spacelike

[imatfaal]

 

 

A 2-dimensional object would be a line, so yes a string could easily be called 2-dimensional. The thing is to keep in mind is what area of physics you are in and also that nobody is really certain. The best we could do is answer your question based on what theory or area of physics you are talking about at that moment.

I have answered it for classical physics (and the answer was "no"), but I can't truly say what the answer would be for string theory. Perhaps someone else on this forum is well versed in string theory and could answer your question from that perspective. But neither of them could be considered as the "definitive answer" to your question. So you may have different (conflicting) answer, depending on what regime of physics you are in.

 

But just keep in mind that the word "particle" is probably used to imply different things. In mathematics it almost always means something with 0-dimensions. But, for physics in general I would just assume the word particle refers to the physical manifestation of the fundamental object (electrons, quarks, neutrinos, etc...), which I suppose could be 2-dimensional in string theory (but again, I do not know string theory).

 

Sorry for all the editing.

 

Surely a two dimensional object has area - ie length and breadth. strings only have length - they are 1-d objects. A 2d object would be a membrane or 2-brane

[spacelike]

Surely a two dimensional object has area - ie length and breadth. strings only have length - they are 1-d objects. A 2d object would be a membrane or 2-brane

 

Right >.<

 

Sorry I really don't know what I was thinking when I wrote that, thanks for catching it.

and I really don't think I should comment any further on the string theory aspect of this

[imatfaal]

Right >.<

 

Sorry I really don't know what I was thinking when I wrote that, thanks for catching it.

and I really don't think I should comment any further on the string theory aspect of this

 

Me too - that has exhausted my understanding of string theory!

[Schrödinger's hat]

do 2dimensional particles exist? i have heard about something called strings [sub-atomic] which they say are 2d

 

 

There's also a thing called an anion which is a solution to certain quantum physical equations which does not exist in three dimensions (or higher...I think?).

They have certain properties which make people think they may be useful, so some physicists are trying to create really flat potential wells (sort of squeezing some stuff with lasers) to try and create them.

[DrRocket]

A 2-dimensional object would be a line, so yes a string could easily be called 2-dimensional.

 

A line (or even a smooth curve) is 1-dimensional.

 

A surface (locally a plane) is 2-dimensional.

Edited September 10, 2011 by DrRocket

[ajb]

Strings are one dimensional objects, they are either sections of a line or are circles. As such they sweep out two dimensional world surfaces. This maybe where the confusion comes from.

[khaled]

I just imagined a 3-dim circular curve that takes the shape of a ball,