The idea of multiple universes is a hot topic in astrophysics: that our universe is just one bubble in a collection of other universe bubbles that make up the multiverse or meta-universe (some multiverse hypotheses discuss multiple universes as membranes or sheets, others as discs). While the main focus is the speculation about alien realities that may (or may not) exist in our universe, no discussion of alien realities would be complete without touching on the subject of alternate or parallel universes.
But before we venture too far into alternative, parallel universe conjectures, I would first like to examine the intersection of the subject of parallel universes with that of alien contact. While the idea of alien contact is plausible in our universe, it may be rather implausible between two universes.
Some hypotheses, like the Many Worlds Interpretation (MWI) or quantum multiverse, state that different universes arise “merely” from the random fluctuations that happen on a quantum level. Chance and true randomness exist and create multiple universes. Einstein did not much like the idea; he did not like what the math and the theories were suggesting. He could not believe that God plays with dice.
In a random event, there is more than one possible result. In the MWI, for each random event, each possible result occurs: one occurs in our universe, and the others occur in newly created parallel universes. Thus, those universes have the same physical laws as ours, with the exception of a few minor changes in a quantum level random event.If aliens were somehow able to travel from one of those parallel universes, they would enter a space-time continuum that would function the same as it did in their home universe. Though MWI states that no communication between the universes would be possible, thus no travel, although there could be quantum interference between them, I doubt much could be communicated that way.
Other hypotheses predict changes in physical laws for each universe. This would have major consequences for any alien explorer from another universe. If parallel universe A’s gravitational constant, for instance, is stronger than universe B’s, then everything in universe A would come into existence, work toward equilibrium, and evolve within this stronger gravity.
And, because gravity is a component of the space-time continuum, the very fabric of space, aliens from universe A would find themselves in a different space-time continuum—one with weaker gravity.Their bodies, their evolution, and their spacecraft, as well as the materials within them, all grew, lived, and evolved in or were designed for stronger gravity.
This would affect them at both the atomic and macro levels. It would affect every particle of their beings and every particle of their ships. Small changes in physical laws can have a big impact on physical structures (both living and inorganic).It would be very dangerous, even lethal, to pop into a parallel universe without checking the conditions; the aliens would need to send over a M.A.L.P. (Mobile Analytic Laboratory Probe; yes, I’m a Stargate fan, though I doubt that would surprise anyone). Though it raises the question that even if they were able to send over something like a M.A.L.P. first, could they truly trust the readings they get back since they are using sensors that would be affected in unknown ways by the unknown differences between the universe being investigated and the home universe?
It would be best to find a means of communicating without actually physically setting foot in another universe. One possible way of communicating may actually be via gravity; some hypothesise that gravity may leak out of universes or otherwise be felt by other universes. If that is the case, it may be the most logical way to conduct inter-universal communication.Wouldn’t that be wild—to communicate with a sentient species in another universe?
Perhaps the safest way as well: if the other sentient race turns out to be a war mongering conqueror, we would have little to worry about (as long as each universe is incompatible with life in the other); though I wonder if they could eventually figure out how to use a gravity wave weapon, and what would it profit them to do so? Of course, we’ve seen on our own planet that some people just cannot tolerate anyone different from themselves, and that is reason enough for them to murder.
