I have some preliminary thoughts on the possibility of multiverses and would like to vet them through the membership here.
Herbert Sweet ------------------------------------------------------------------------------------ Are Multiverses Possible?
The speculation on Multiverses or multiple universes reaches as far back as the nineteenth century. Could such a thing be possible?
The answer ‘anything is possible’ first comes to mind but that doesn’t get us very far. To get a better answer we need to start with what we know and work from there.
What we know about the universe is that it consists of space, time, matter and energy and we know more about each of these than we think we do.
Space not only is what separates the heavenly bodies it is what separates the most elementary particles of matter – what ever they are ultimately determined to be.
Time is what separates events. Events are fundamentally the movements of matter or energy through space. There is a commencement, a continuation and a completion. Time is the relationship not only between these stages but is the relationship of the stages to other events. The clock itself; whether measuring the movement of sand in an hourglass, the movement of heavenly bodies such as the earth or the activity of atoms; is measuring the commencement, continuation and completion of an event.
Energy is the flip side of matter which propels it through space. We all know that E = mc 2.
Without matter there would be no time to denote its movement through space as time is but the measurement of that movement. Without particles (matter), there would be no space to separate them as space is what separates particles. Without space, there would be no separation between particles and therefore there could be no particles at all as they would all be fused together. Without energy there would be no matter. Without matter there would be no energy. If there is no ‘E’ on one side of the equation, then there is no ‘m’ on the other side.
As each of these elements is completely wrapped up in the other three, none exist independently. We can only conclude that the universe not only consists of space, time, matter and energy but the universe IS space, time, matter and energy.
If each of these elements is interdependent with each of the others, then none could exist separately outside of the universe. There would be no abstract ‘fields’ of space or time or energy as some have thought.
This common concept of space or time or energy as an abstract foundation for matter is but an extrapolation of the practical reality of these elements. This is no different than any other straight line extrapolation that assumes that activity further removed is the same as what is currently experienced. We’ve seen this before when people extrapolated their observation of a flat reality to the notion that the entire earth was flat. Haven’t we just increased the scale of this kind of faulty logic?
But to speculate that there are multiverses, we need to establish that there is something from which they can arise – some soil for the plants to grow in. If there is no underlying ‘field’-- no field of energy, no field of time, no field of space-- then there is nothing from which the many universes could arise. Knowing what each of these fields is, we can not conclude that they could exist separately. And even if such was possible, is it reasonable to speculate that any one of these fields could give rise to a universe in which it was but one of the constituents?
Could there have been other points from which other universes arose such as the point from which our universe arose? Behind this question is a hidden implication that is based on our everyday perception of reality. It assumes that there was a time and place from which our universe arose and all other universes could have arisen. But to suggest such, we are unwittingly speculating that there must have been a field of time and space to start with which seems unlikely as previously discussed. So as enticing as the multiverse speculation may be, as we look more closely, we find nothing to sustain it.
I suspect that you are asking whether they are physically possible. But, based on the way that we use it, "physical" means part of this universe. So the other universes in a multiverse would not be physical since they would not be part of this universe.
Apart from that technical point, I don't see the problem.
Whether discussing other universes is useful - that's a different question. I'm inclined to doubt the usefulness.
Christianity claims the moral high ground it its rhetoric. It has long since abandoned the moral high ground in its practices
Ghost are a derivation of the physical. Some aspect of reality is imagined. Luck and fortune are descriptive of one's relationship to the physical including the relationship to other (physical) individuals. Love is descriptive of a relationship with another (physical) being although some people claim to love things. Beauty is simply a rating, of sorts, of how some particular individual or thing is perceived. A dot or straight line is relational to a three dimensional object or, abstractly, to any three dimensional object.
Not only possible, but inevitable. However, you are using the term in a much stronger sense than we use it in theoretical physics. The Observable Universe is only one infinitesimal corner of the potentially (and at the very least, practically) infinite Universe. Each of the infinitude of other infinitesimal corners makes a separate non-observable universe, and thus the Universe can well be regarded as a multiverse in its own right. These other corners may well (and in some cases will necessarily) have very different low energy physics to that which we are accustomed. This alone gives the perfect multiverse to explain anthropically just about every "fine-tuning" example that may be raised.
There are many other examples of multiverses, as Max explains on his site (that is referenced in the post above), and we can explore these in greater detail if required.
In response to nwr I questioned the ability to conceive of anything that wasn't physical. My response to you has been that you have been listing qualities of the physical. Whatever we think eventually is derived from the physical.
If someone suggests a non physical universe, I don't believe that anyone can make any sense out of that other than a sci-fi writer.
My quick take on Max Tegmark is that his speculations are based on an infinite base of space. I questioned the rationality of this as the foundation would have had to have manifested as but a component of each universe generated. By this logic, if there is a foundation outside of our universe and any other possible universe, it would have to be something other than space, time, matter or energy.
Cavediver, The multiverse answer also needs to be probed for the psychological need for an alternate to the anthropic. Some detachment from science itself is called for. What I am referring to as the scientific split from religion in the 17th century having left a long lingering discomfort with any kind of non material explanations.
The anthropic, BTW does fit in very nicely with the earliest of Indian (Vedic) thought. There it is said that underlying the material reality is a non deified Intelligence and that the evolution of its manifest relative reality is Intelligence getting to know itself.