Or from our 3-D perspective, particles can precipatate out of space.
That is my explanation for the origin of cosmic axions.
Early in the history of the universe when it was still very hot- its photons were very energetic- those photons were constantly producing pairs of electrons and positrons in 9-D space with 6 dimensions of space compactified. As these particles flew apart they remained connected by strings of compactified space. Then when the particles interacted with other particles, such as in annihilation events (called recombination in cosmology), the particles became photons again and the strings became axions in 3-D space. Thus cosmic axions came directly from compactified space.
Perhaps all particles also come from space. But since electrons form in 9-D space, some higher dimensionality space must have compactified to form 9-D particles. That is consistent with the universe basically having 26 dimensions.
Only bosons can exist in 26 dimensions. The strings are all closed and have integer spin. Open strings have (multiples of) half integer spin and cannot exist in space with higher dimensionality than 9. The 26-D bosons are then the unified field. Then 16 of these dimensions compactify into physical particles or matter in 9 dimensions plus time.
An interesting aspect is that in 26-D string theory, there are two time-like dimensions and that one of the time-like dimensions is compactified in the creation of matter.
That is, we physical 3-D bodies live on a line in time, but the unified field lives on a plane of time that may allow for time travel to different points of time on our time line.
Going back to the cosmic axions, it seems that we should expect different kinds of cosmic axions as the universe passed through several stages of particle pair creation and annihilation.
Electron/positron was just the last one. When the universe cooled below the level for e/p creation, all the positrons recombined with most of the electrons producing the light we see today in the background radiation plus the last allotment of the lightest cosmic axions.
Previous to this event when the universe was much hotter, the photons were energetic enough to produce quark/anti-quark pairs, which then flew off in 3-D space connected by heavier cosmic axions. Several levels of axion masses were thereby produced.
Since the axions are so light in mass, or better said, they are so massless that they form Bose-Einstein Condensates (BEC) at room temperature, and perhaps even solar temperatures and since the extent of their wave functions is dependent on their masses, the higher mass axions would form condensates that are quantum coherent over smaller scales. The lightest cosmic axions coming from e/p recombination are coherent over at least global scales.
Those coming from quark recombination are about a thousand times smaller in scale, or about kilometers in scale, and possess superfluidity up to room temperature only. Even higher mass axions are not BEC at room temperature and are not of interest. It is likely that they are not stable and break up into lighter axions. The axions generated from quark recombination may do the same since they come from the original compactification of the 16 dimensions discussed above.
So the bottom line is that the axion condensate acts like a single particle over global scales. If there were even more massless axions or other type particles, they could be coherent over say galactic scales. Exactly massless particles are coherent over the scale of the universe and they make up space itself. 3-D space is in this context just a BEC of massless particles that have no inherent motion. |