Indeed, if certain objects could move infinitely fast, we might expect to find the universe populated with large sets of indistinguishable particles, all of which are really instances of a small number of prototypes moving infinitely fast from place to place, so that they each occupy numerous locations at all times. This may sound implausible until we recall that the universe actually is populated by apparently indistinguishable electrons and protons, and in fact according to quantum mechanics the individual identities of those particles are ambiguous in many circumstances. John Wheeler once seriously toyed with the idea that there is only a single electron in the universe, weaving its way back and forth through time. Admittedly there are problems with such theories, but the point is that causality and the directionality of time are far from being straightforward principles.

— 1.7  Staircase Wit

— Reflections on Relativity

— mathpages

2013.05.17 Friday ACHK

Any particle can be exchanged in some context or another. So every kind of particle in one way or another produces a force.

In molecular physics, it’s the exchange of electrons which creates force [in covalent bond]. In electrodynamics, it’s the exchange of photons back and forth which creates force.

So [every] particle is connected with a force when that particle can be exchanged or jump back and forth between two something else.

There are people say that there are [only] four forces of nature.

No.

There is a force of every possible kind of particle.

— Lecture 1 | New Revolutions in Particle Physics: Standard Model 

— Leonard Susskind

2013.05.13 Monday ACHK