Philosophy Discussion Forums

There's been discussion about different universes and what we mean exactly by it.

I did a thread before on the multiverse. This thread, I'm not looking into whether they exist. This time, I'm checking into what characterizes a multiverse? The answer to this depends on what characterizes the universe we live in. This is why I placed this thread in the science category.

I turn this discussion to the floor.

PhilX

What is the multiverse, Phil?

The multiverse is the physics of the gaps and no physicist takes the idea seriously. It is a clever mathematical device to model many of the conundrums inherent in Quantum Mechanics, rather like the hidden dimensions of string theory. To explain the utility of such models is a fiendishly difficult mathematical exercise and I freely declare myself unqualified to do this in any meaningful way. Even if I could I very much doubt that anybody here would be very interested in following it because I'm not. I know why they do it but not exactly how.

Notions such as the multiverse catch the attention of the populist media which is always on the lookout for scientific curiosities to further confuse its lay readership. I guess it's just the times we live in. Nobody wants to let the facts stuff up a good story.

Regards Leo

Are there no gaps in physics?

Theophane wrote:Are there no gaps in physics?

Too right there are. Physics is full of gaps, which is why physicists play with hypothetical models to fill them. The tricky part is testing these hypotheses and needless to say the multiverse hypothesis is untestable. This is why physicists take none of this nonsense too seriously and just play with it mathematically. Believe it or not this can be very helpful for them to tighten up the parameters of their more probable models but it doesn't really tell them all that much about the universe we actually live in. For laymen like you and I this is all we care about but these blokes live in a different world where such questions are little more than an inconvenient distraction.

Regards Leo

I'm borrowing from O+ (from a different thread about the true nature of philosophy):

"Questions about the possible existence of multiple universes depend largely on which definition of 'universe' is accepted. If broadly defined to be absolutely everything then saying there can be multiple universes is like saying there can be multiple everythings. This doesn't seem to make logical sense. If defined more narrowly, allowing the possibility of something to exist beyond the universe, then the concept of multiple universes can be given more consideration."

PhilX

It's a good point, Phil. If there are universes outside the universe then the universe isn't the universe, is one way of putting it. From a physics point of view the only universe that we can make any meaningful statements about is the one that "originated" at the big bang so speculation about any others is both ontologically and epistemologically meaningless and must always remain so by definition. I use the word "originate" in inverted commas because the evidence is steadily mounting that the big bang was not the beginning of the universe but rather just the beginning of this iteration of an eternal bang/crunch cycle. Physics can also make no meaningful statements about the previous or future iterations of this cycle because the crunch phase de-coheres its information content. It literally starts all over again which means that reality can never repeat itself on the cosmic scale.

Regards Leo.

What is called the 'multiverse' in current theory is all of the 'parallel' three-dimensional 'universes' which allegedly exist in the world because of the fact that there are at least six dimensions of space, sometimes referred to as dimensions of 'space-time' because they can be perceived either spatially or chronologically depending on the perceiver.

These so called 'multiverses' are said to exist because in this model all the separate moments of time which could have, are, or could be existing are continually and constantly existing side-by-side in the real world of higher dimensions of space. So there could be a 'parallel universe' in the 'multiverse' in which Hitler won WW2. And another 'parallel universe' also exists in which the native american indians defeated the white man, and so on. All moments of the past, present, and future, and also all the moments of the possible pasts, presents and futures all exist together in the 'multiverse'.

I could describe the model but it is very complex. But the general idea in fact is quite sound. In a world of six or more dimensions one can explain how all these 'universes' could exist 'side-by-side' simultaneously.

Atreyu.

It is kind of funny, but I was never comfortable with the BB thinking and that time started with it,and it seems that cosmology is catching up to me.

I feel the same way about multiverses and multi-dimensions. it seems more likely that they do not exist but the present mathematical formulas need them in order to make sense. I believe the math is the problem. We just do not know enough to make proper formulas. When I say we I make no claim for myself, I mean humanity.

Regards, John.

Well, this model is the only one I know of that explains our perception of chronological time and also resolves the dilemma of 'free will versus determinism'. It does not make sense to think of the past as being 'gone' and not existing, and the future as 'not yet here' and not existing. The present moment is too tenuous and hard to pin down to be the only real existence in time. So in this model all of the past, present, and future exist continually as our awareness moves from moment to moment in time. We only take as 'really existing' the particular moment our awareness is on. As it moves to the next moment we say the previous one is 'gone'.

Of course, adding another dimension of 'space-time' can give us a more dynamic universe. All the moments of the realized past, present, and future can explain time, but in that model everything would be predetermined. But in this model not only do all of the moments of the realized past, present, and future continually exist, but also all the possible ones. So it explains the perception of chronological time quite nicely without having to resort to any predeterminism. The past and future were/are not set in stone but yet each moment of our past and future continually exist both after or before we realize them. So the future can exist before our awareness reaches it while at the same time being open to a myriad of possibilities.

"So there could be a 'parallel universe' in the 'multiverse' in which Hitler won WW2."

There's an entertaining novel by Philip K. Dick based on that premise (The Man in the High Castle): http://www.amazon.cm/The-High-Castle-Ph ... 547572484/

In trying to deal with alternate realities or multiverses you leave philosophy and enter the world of fantasy. Logic does not apply and we are only limited by our imagination.

Regards, John.

This discussion can benefit by realizing there are two entirely different theoretical platforms that share the name "multiverse." The first theoretical platform is an interpretation of quantum mechanics from the late 1950s, originally known as the Relative State interpretation, but more popularly as Many Worlds. It was never called the multiverse until just the last decade when the media began confusing it with the 2nd theoretical platform, which is from Cosmology, not QM.

In the cosmological version, multiple universes may have been created by the Big Bang, plus any universe can "spawn" baby universes like bubbles that become closed off from the original universe. In the Many Worlds version, trillions of universes are being created every nanosecond to accommodate the myriad values of all the wave functions of all previous universes as they evolve in time. In scientific literature, "multiverse" has always referred to the cosmologcal theory, not the QM interpretation, though this is probably changing already.

The 2 versions are easy to confuse, but only the Many Worlds version offers the idea of parallel universes. The cosmological version does not.

A Poster He or I wrote:The 2 versions are easy to confuse, but only the Many Worlds version offers the idea of parallel universes. The cosmological version does not.

A useful clarification, Poster. Everett's Many Worlds version isn't really used any more because it was simply an absurd misunderstanding. Primitive QM assumed a non-causal embodiment to nature which was false but taken to mean that anything that can happen will happen. Since this obviously doesn't happen in the real universe the Everett model is an example of "physics of the gaps". It still has some use in the Standard Model, which uses mathematical entities called "virtual" particles which were formerly known as both imaginary particles and shadow particles. It goes without saying that these mathematical confections aren't real but this doesn't detract from their usefulness. In the Everett model the entire universe splits at the sub-atomic level at the rate of 5.4 x 10⁴⁴ times per second. This occurs for every single sub-atomic particle in the cosmos so we're talking a **** of universes.

The cosmological version of the multiverse is to do with inflation. The original Guth hypothesis has had to be extended several times as more inconsistencies are discovered and the latest fashion is the idea of "eternal" inflation where "bubble" universes are being split off and formed continuously. Most physicists accept that this is also just physics of the gaps and it hasn't really lead them anywhere.

String theory has now gone the way of phlogiston but it also used the multiverse approach with its idea of the "hidden" dimensions. This made the theory unworkable because it essentially meant there were 10[sup]500[sup] string theories, one for every possible universe. Bear in mind that our universe contains about 10⁸⁰ atoms so this gives us a sense of scale. The string theorists worked hard and their calculations were fiendishly difficult but their chances of finding the right string theory to correspond with the universe we actually live in were negligible. Even if they had managed to achieve this virtual impossibility it wouldn't have helped them much because they would never have been able to test it. Physics at its worst.

Regards Leo

The idea of 'parallel worlds' is actually quite sound based on higher dimensional theory, which is in itself quite sound. It's true that no one has been able to move it into the realm of ordinary physics, but I wouldn't expect anyone to. However, higher dimensions of 'space-time' are the only way to explain our perception of chronological time, and using six of them gives us the kind of Universe envisioned by the 'multiversists'. The problem is that most people find higher dimensional theory difficult, and are unable to visualize the higher dimensions of space, particularly how they are embedded in our perception of motion/time. But once one can do this it all becomes very clear.