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I found this youtube video on DVice,  and while it is very simplistic, it covers most of the bases (basics) and offers a few new(er) theories to consider.  It seems that one of most difficult concepts to accept logically, especially by someone with merely a passing knowledge of the sciences, is that the physics of our universe began as a result of the big bang, and that time and space are a function of physics, and thus did not exist prior to the event in question.  More after the jump.

What this means, of course, is that prior to the event, or “Big Bang”, there was nothing.  No space.  No time.  No BOSONS.  Bosons (Photons, K and W- Bosons, Gluons, and the expected Higgs) are those little quanta that somehow jumped into existence some time after this initial period of inflation and effectively allowed space-time to begin it’s existence.  What was in the area before the big bang?  The short answer is; there was no area.  The physics did not yet exist to define a space with any kind of volume or area.  Is it possible that a different space with physics (even if it were different physics) existed prior to the existence of our universe?  Yes but not likely given the entropy problem; that if you allow for time and space to go back for an infinite amount of time, it would by now have already reached it’s final state (stasis) where all temperature is equal and all motion has ceased.  The wrinkle in this is that in the theoretical expanding/contracting/repeating model, the complete obliteration of information (history) from a previous universe would guarantee that it’s existence is meaningless to the subsequent one, and therefore might as well not  have even existed.

Our view of the universe is completely dictated by bosons.  If photons traveled at one foot per year instead of 186,000 miles per second, we would be able to look across the street and see events from 50 years ago.  Similarly, if the gluons that bind quarks together in the atomic nucleus were slightly weaker, atomic nuclei might be much larger and fly apart with the force of a nuclear explosion with the slightest provocation.  Same goes for W- Bosons, which mediate the distance of the leptons from the nucleus.  A slightly different value, and individual atoms would no longer be able to interact the way they do now.

In short, a universe whose physics were even the slightest bit different than ours would likely be unrecognizable.  It could be much larger or it could be infinitesimally tiny.  It could be completely devoid of coherent matter or it could be a giant blob of plasma.  Time could flow faster or slower or even backwards.

So we come now to the idea of multiple universes.  In the time before the big bang, there was no space, or at least nothing that we could handily describe as a space or anything else.  Let’s call this “stuff” the medium.  Within this “medium”, our universe was created in a huge flash of energy.  Could this have happened elsewhere in this medium?  And if so, how many times?  Since the two most common values in our universe are One and “Holy shit, that’s a lot!!”, I would guess that there would be too many to count.  This multiverse theory, to me, raises a lot of additional questions.  Should we be able to eventually see them?  Not likely, as there are objects in our own universe that are so far away and whose relative motion to us is so great that the light being emitted by them will never reach us.  If crossing the “medium” is a matter of distance, then it is likely that that distance would make the vast distances between stars at opposite ends of our universe seem trivial.  Can we interact with them, somehow?  This is where it gets dicey.  There are things that happen at a subatomic level that seem to indicate the presence of alternate or additional dimensions whose physics is decidedly different from ours.  Quantum entanglement and quantum tunneling are both phenomena which in some ways defy the laws of physics as we know them.  Entanglement implies communication and exchange of information between particles at speeds (speeds which theoretically approach infinite values) beyond what is permissible according to Special Relativity.  This violation might be permissible, however, if the particles communicated outside the frame of our universe or outside the dimensions of space in which we are able to observe physics.  The other energies imparted by Bosons may similarly be “drawn” or taken from alternate dimensions or universes.   Another question is that of relative motion in this “medium”.  If there are multiple universes in the “medium” then it is also likely that some or all of them are in motion relative to each other.  If this is the case, then it is also possible that we may be actually traveling through the “medium” at many many times the speed of light when compared to other objects in the medium.  This does not present a problem for us at all if we consider the universe we exist in to be “closed” and subject to only it’s own physics and therefore the only motion that matters is the motion within the “borders” of the universe.  It does, however, present a problem when you think about opening a gateway into a different universe.  A layman’s understanding of relative motion begins to fall apart when you talk about unbinding the rules from gravity and fixed points in space.  If you picked a fixed point in space (CMB rest frame) and stood in it, the galaxy would begin racing away from you at a speed of 552 km/s and the sun would be racing away even faster, since it is in motion within the galaxy at about 220 km/s.  With that amount of relative motion, combined with the relative motion between two universes, you would almost certainly have to have similar rules of gravity in both universes in order to have a chance of anchoring any type of bridge or gateway.

Another problem in both quantum physics and cosmology is that the universe is almost all empty space and there is no reason to believe that any alternate universe would have any massive particles at all, given that they seem to be relatively rare in ours.  At the quantum level, if you were to put a basketball in the middle of the field at Giant’s stadium to represent the nucleus of a hydrogen atom, it’s corresponding lepton, an electron, would be represented by a softball circling the outer rim of the stadium.  That leaves a whole lot of space.  Similarly, if the basketball represented the earth, the sun would be represented by ball 109 times it’s diameter (about 30 meters tall) located more that 3 miles away, maybe on the Hudson river. Pluto would be represented by another softball in the North part of Baltimore, 150 miles away.

The overall  density of the the universe is very low, roughly 9.9 x 10^-30 grams per cubic centimeter and roughly 96 percent of that mass is in the form of Dark energy (73%) and cold dark matter (23%).  The remaining 4 per cent is ordinary matter, much of  which we can observe directly.  The prevalence of ordinary matter in the universe is on the order of roughly one lone hydrogen atom for every four cubic meters of volume.  Matter, therefore, appears to be anomalous and in this universe, it is quite rare.

The idea that multiple universes might exist is beautiful, romantic, and hopeful.   If we were able to interact with them, we might be able to use their properties to travel vast distances in very little time, or to create vast amounts of energy with little effort.    These and many other theories may ultimately herald the next step in evolution and carry us to the stars and maybe beyond.  There is no evolutionary path for man that does not demand a better understanding of the universe and it’s nature.