In an infinite universe every possible event occurs an infinite number of times- it is argued that this means infinite regions of space- FAR beyond our observable universe- harboring worlds and occupants indistinguishable from us- and infinitely more with world’s just slightly different… This is discussed in detail in Brian Greene’s ‘The Hidden Reality’ and Max Tegmark’s ‘Our Mathematical Universe’.

Furthermore, theory strongly suggests that there are infinite universes where the fundamental constants are different- this allows us to avoid the assertion that our universe is ‘Fine tuned’ for our type of life- All possible combinations of values for fundamental constants exist, including some that are precisely right for our existence, naturally we exist in one of these universes.

On top of this incomprehensible infinity of infinities is another infinity multiplying them all- this time arising not from the Mega-macroscopic theories of cosmology, but from the the microscopic world of quantum mechanics.

The ‘many world’s’ interpretation of quantum mechanics is a less artificial interpretation than the copenhagen interpretation that invokes- without any mathematical rigor- a collapse of the wavefunction. The many worlds interpretation suggests that all possible outcomes of any quantum event actually happen and are all equally ‘real’…

There are more possible infinities on top of these… but at this point it starts to get REALLY weird….

Long story short- as we learn more, the more it seems that our universe is infinite, and that everything that CAN happen in our universe WILL happen an infinite number of times. Furthermore there are infinite other infinite universes with different fundamental constants where anything that can happen will happen infinite times. On top of all this, every possible quantum event in these infinite universes does happen creating another equally real universe….

And I haven’t even mentioned ‘simulated universes’ within these universes, or Boltzman Brains or quantum suicide- feel free to google those… and never sleep peacefully again…

Quadruple star systems featuring two binary pairs are nothing unusual, nor is the discovery of a surrounding protoplanetary disk—a ring of gas and dust that gradually congeals to form planets. A star system located 146 light-years from Earth, called HD 98800, has all these things, but as new research published today in Nature Astronomy reveals, this system features an exceptionally strange protoplanetary disk.

Many stars in the heavens appear “double”, even to the human eye, and although some are accidental or chance line-of sight alignments, many are actually gravitationally connected pairs. Some binaries are extremely close, even in physical contact, and can only be detected by the variation in brightnerss as they eclipse each other (eclipsing binaries). Others can only be deteced spectroscopically, their spectra are the superimposed spectra of two or more stars. Still others can actually be observed to rotate about one another, with periods raising from hours, to centuries, depending on how close the stars are to each other. Others are so far apart they show no evidence of gravitational connection, and are only suspected binaries because of a shared proper motion and radial velocity.

Our nearest stellar neighbor, Alpha Centauri, is a triple star system, two fairly close bright companions orbiting one another at distances comparable to the scale of our own system (they are easily resolved in amateur ‘scopes) And a third, a dim red dwarf Proxima, in orbit around the other two in a very elongated eliptical orbit. Look up the Wikipedia entry on this trio. Its a fascinating system.

Binary stars are the rule, not the exception. Over half of all stars are known to be members of binary systems, and triple, quadruple and even higher level hierarchies are not uncommon. Since many binaries are extremely difficult to detect, binaries may be even more common than we know and it is likely that solitary stars, like our sun, are quite rare. Even the sun might be considered a sort of binary, since Jupiter is close to the arbitrary boundary between star and planet.

Of the eight major planets in our system, 6 have at least one satellite and many minor planets and Kuiper belt objects have companions. Galaxies often have satellite galaxies, and many seem to be orbited by clouds of globular clusters.

Satellites seem to be a normal part of the mechanism that allows objects to condense from flat, rotating clouds of orbital debris. And the process appears to be hierarchical. Although none of the satellites of planets and planetoids in our solar system have their own satellites (probably due to the gravitational perturbations present in the crowded cis-solar environment) among stars there does seem to be a hierarchy: binary stars are often orbited by other stars or binary pairs, and pairs of pairs and so on. I read somewhere that one star has eleven known companions! Any theory that describes the process of planetary formation has to be able to explain this.

Some binaries are very close, with the stars actually in physical contact with each other. Many others are distant, with the members so far apart that only the most subtle and indirect methods can reveal their binary nature. How the distances between binary members is variable, that is, how the distances are distributed in stellar populations, and how that distribution may (or may not) be related to the mass ratio of the two members has (as far as I know) never been properly investigated. This may be due to the fact that many binaries are difficult to detect, so we don’t have enough data to make proper comparisons, but these new orbital observatories make that possible now.

Many orbital configurations are dynamically possible, but don’t seem to exist in nature, either because they inherently unstable or simply because Nature doesn’t like them. And the orbital resonances one sees, like the Kirkwood Gaps and the Pluto-Neptune Coupling seem to emerge from this chaos almost unexpectedly (although why they do so seems obvious once you actually see it happening!). Its funny how something as simple and straightforward as Newton’s Law of Gravity can manifest itself in so many subtle, complex and surprising ways…