# B Point-Like Particle Dimension

1. Nov 16, 2016

### ChrisisC

How is it possible that a point like particle is 0 dimensional? Could it only
exist within pure mathematics? or actually exist physically in our universe?

2. Nov 16, 2016

### mikeyork

A point-like particle has no internal dimensions. It can still exist in an external observer's space-time frame.

3. Nov 16, 2016

### secur

A point-like particle, with exactly 0 dimensions, is a mathematical abstraction. As far as anyone knows it seems to apply to something like an electron. But the common-sense view would be that it has 3-d extension in space like any other physical object, it's just too small for us to experimentally perceive its size.

The question is complicated by the fact that it can, mathematically, be considered as an "excitation of the field", or as a "wave function". IOW it's not a particle at all but behaves like one, usually, from our point of view. That's certainly possible. Look up "soliton" for an example of analogous macroscopic wave behavior.

Another complication is that some physicists are willing to consider it actually 0-dimensional, and yet (somehow) existing anyway. IMO that's just pseudo-science.

4. Nov 16, 2016

### mikeyork

To you maybe, but not to many well-respected physicists. It just requires the notion that our 3d space is not fundamental to the particle but part of an observer's representation of particles (just like temperature of a macroscopic system is a representation of the energy of constituent particles). This has been a growing idea for the last couple of decades. Check out, for example,

van Raamsdonk M., Building Up Space-Time With Quantum Entanglement'', Int. J. of Mod. Phys. D, 19 (14) 2429-2435 (2010)