Why do experimental physicist use the term multi-verse?

tvolpe

Why do some theoretical physicist use the term multi-verse, this seems to be a logical contradiction? If their theories were correct wouldn't it be more logical to call our phenomenologically observable universe a cosmos and everything within and outside this cosmos the universe?

phinds

Some of the multiverse theories posit totally disconnected universes, so no, your terminology wouldn't work. They really do mean multiple universes, not sections of our currently known universe. (and by "known" I don't mean "observable", I mean all of it ... whatever that means)

tvolpe

Let me rephrase. While I understand that this is a gross simplification, say for example you had two 3-branes each of which was completely disconnected and each of which birthed a "universe" from discontinuous big bangs. Wouldn't each one of these separately be a cosmos and the two together the universe? I'm just going off the definition of universe derived from the latin term uni- that means one; having or consisting of one. The universe would be the unified whole of everything. Philosophically it seems to makes no sense to have multiple unified wholes of everything.

Vanadium 50

I know of exactly zero experimental physicists who use the term "multi-verse", and for that matter know of very few who even care about this. When you're trying to measure the band gap of glopolium, thoughts of multiverses don't enter your brain. Who are you talking about?

marcus

I'm drawn to your point of view. At some level language usage is a matter of taste, but it involves the collective preference of the relevant community. If it were up to me, my taste would be to continue using "universe" for the whole reality that physics is about. And if it turns out to be divided into regions then have another name for the regions.

To me the word "multiverse" has a kind of "attention-getting" sound. The novelty (emphasized by an obvious contradiction in terms) appeals to the general public.

Nowadays I don't see the word used much in theoretical physics or cosmology professional writing. In houseso to speak, there was a kind of fad that got going in 2003 and may have peaked around 2007.

Now the main venue for multiverse talk seems to be public lectures, popular books and media. Only a relatively small number of technical papers for professional audience. That's my impression anyway. It does have boxoffice appeal, goes over big with the general public.

The indicator that I watch is the lineup of invited talks at the annual strings conference. At Strings 2005 they had serious discussion about the "Landscape" of equally likely versions of physics that you get from String and about the Anthropic Principle that limits the range of versions that we could live with. At Strings 2008 there were no "Landscape" talks and no "Multiverse" talks. The organizers ruled that topic out. That has essentially been the case ever since. But at every Strings conference there are one or two public lectures of an evening, after the regular session. That is when they might have someone noteworthy talk about the Multiverse. The organizers of Strings 2011 actually scheduled Stephen Hawking to give one of those public lectures, but he couldn't make it and his daughter delivered the talk.

So AFAICS the temperature has cooled quite a bit (at professional level) since, say 2005-2007.

Your point about language reform is well taken. The community might sometime adopt some other word like DOMAIN for a spacetime region governed by some definite set of physical laws with fixed values of the physical constants (that get plugged in to the equations of the laws.)

The the UNIVERSE (all physical existence, the entirety of Nature) might or might consist of a number of Domains, each operating under its own set of laws with its own set of constants. The Domains might be totally disconnected or there might be some kind of linkage that future theorists dream up.

Personally I don't find that kind of speculation interesting. I don't think we even begin to understand well enough the set of laws governing the chunk of existence right under our feet and in the sky over our heads. That's what I think is beautiful and exciting, whatever you call it. And why not call it "universe".

But you make a very reasonable point about straightening out the language. Maybe someday it will be done. It is very hard to change language though, once some usage gets entrenched.
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EDIT: I see Vanadium's post. He is right about EXPERIMENTAL physicists. They have never talked about "multiverse", never shown any interest AFAIK. You probably meant to say theoretical physicists. They USED to talk more about it, but the buzz has somewhat died down. Now it is more for a small number and for public lectures and media, I think.

tvolpe

Sorry, my bad I miss spoke, I meant to say theoretical physicist and was referring to string theories. I have also heard many physicist refer to it in the popular media.

tvolpe

Thanks for the clarification marcus. I am a philosopher so I was probably just thinking to hard about the whole thing.

fzero

If you are not familiar already with the Tegmark classification of multiverse theories, you might take a look. The level I (inflation takes place differently in different patches) and II (fundamental constants are different in different patches) hypotheses are the relevant ones for your brane example, while level IV encompasses the further abstraction that phinds and marcus are referring to.

Type I and II are fairly "realistic" given the concrete foundations of quantum field theory and general relativity taken separately. That is, it is not a big stretch to imagine that there is some new physics involving a field that can cause inflation in some other patch of the universe, whether or not inflation is the correct explanation of our "cosmos." Such a minor addition to the Standard Model is a natural point of speculation that doesn't depend on quantizing gravity. Nevertheless, even these examples would, by definition, be beyond the possibility of experimental confirmation. In a real sense, Tegmark's classification corresponds to specifying how wild the speculation involved is.

In types I and II, your point about terminology is fine. We could call the universe in your example a cosmos, or, in a more concrete setting, our observable universe a cosmos. The rest of "space" would be the universe, though practicing theorists have been calling that the multiverse, while each cosmos is a "universe."

tvolpe

Thanks for the reminder about the Tegmark classification, I came across it when I first got into this field, but it has since faded from my mind. I will research it further when I get a chance.
To be honest however, I am more concerned with and informed about neurology, conscious studies and psychology. However, I feel both ontology and theology have gotten themselves in a sort of intellectual void by refusing to explore science, and have found interest in string theory (that I personally do not believe is science, but mathematical philosophy) so that I can avoid theological and ontological theories about the origins of our cosmos.
I did not post my ontological theories about the universe as to avoid breaking the forum rules and instead was attempting to skirt around directly posting my extremely speculative theories. I know my larger theory will get most of the specifics incorrect, but these inconsistencies would be largely inconsequential for the implications of my large work. However I was wondering if these terms make sense to anyone who is more familiar with the subject matter?

I term the rest of space a field of immanence (FoI) (I have also consider the terms realm or domain of immanence and after marcus's suggest i'm leaning back in the direction of domain) that would be populated by branes of temporal immanence (BoTI) (purely as an assumption to avoid the origin of these branes, from what I understand they would have to be created somehow and would therefore be imminent). I conceive the interiority of these branes as a latent vector field and their exteriority as a scalar field or more specifically a Higgs field.

Here is a brief summation of one of the sections about about the formation of our cosmos with the chapter it is under.

Realm of Becomings: the Cosmos (becoming-in-itself), and the Worldly (becoming-in-itself/becoming-for-itself)

The Cosmic Assemblage

If BoTI, within the FoI, collide the interiority (a latent vector field) of each BoTI would be “thrust” into the exteriority (a latent scalar or Higgs field) of each BoTI. As previously described, this would lead to the creation of an inflaton field and the birth of two cosmic assemblages.
After this collision and the subsequent rebounding of each BoTI, the interiority of each BoTI becomes a plane of spatial immanence (PoSI) or gravitons, and two planes of imminence (PoIi) ((species a) a fundamental boson, the unification of the three gauge interactions of the standard model and (species b) a fundamental fermion, or a fundamental particle of mass). PoIi (b) obtains its mass (become a scalar field from a vector field) because the exteriority of each BoTI acts as a latent plane of immanence (LPoI) or a Higgs field, whose mass can be “captured” by the PoIi (b), to become the fundamental particles of mass as they roll into the LPoI. After this “capture” is completed the LPoI is “drained” of its mass, falls to its point of lowest energy and becomes a vacuum.
Throughout this vacuum and across there immanent line of flight (ILoF) the PoSI and PoIi continually engage in processes of territorialization. (The immanent line of flight is conceptualized as the arrow of time earlier in the work. This is because the PoSI and PoIi are theorized to return to the BoTI through a unified black hole and therefore they have an immanent destiny or death) ( additionally this vacuum + the ILoF = 4D space-time in my theory). Each of these processes of territorialization is a differentiation of the cosmic assemblage, or an imminent line of flight (IiLoF) from the cosmic assemblages previous states of being, all of which are interconnected across its ILoF.

Thank you all for your time and patience. If anyone is a moderator could you please move this thread instead of locking it, I am wholly open to critique and ire, but I need some sort of feedback because non of my colleagues have any idea what I am talking about.

marcus

I'm not a moderator and I don't know of any sub-forum in the Physicsforums (PF) structure where your discourse would naturally belong. So I can't imagine you encountering either "critique or ire". The thread is in danger, I suspect, of locking or erasure, simply because it is not ASSIMILABLE within the PF categories of discussion.

I will give you feedback because you say you need some. The most important and urgent question in Philosophy of Science (PoS) these days is why these laws?
Given the present historical situation you need to basically revise your approach. You are accepting current approximate ideas of what the laws are and intellectualizing them, reconceptualizing them, re-naming stuff etc. This won't gain you any listeners. You have to go deeper.
What is a "metalaw" structure of rules by which the present regularities (patterns laws...) which we observe might have evolved?

You also need to connect with the professional PoS literature on this.
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My advice would be to use this link
http://arxiv.org/find/grp_physics/1/.../0/1/0/all/0/1
to find and read these recent papers:

2. arXiv:1205.3707 [pdf, ps, other]
Precedence and freedom in quantum physics
Lee Smolin
Comments: 12 pages, latex, no figures
Subjects: Quantum Physics (quant-ph); General Relativity and Quantum Cosmology (gr-qc)
3. arXiv:1202.3373 [pdf, ps, other]
A perspective on the landscape problem
Lee Smolin
Comments: Invited contribution for a special issue of Foundations of Physics titled: Forty Years Of String Theory: Reflecting On the Foundations. 31 pages, no figures
Subjects: History and Philosophy of Physics (physics.hist-ph); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
4. arXiv:1201.2632 [pdf, ps, other]
Unification of the state with the dynamical law
Lee Smolin
Comments: 13 pages, no figures
Subjects: High Energy Physics - Theory (hep-th)

The third would be the one to focus on, I think. In the Newtonian legacy the state is a configuration of the world which evolves according to laws. But to explain how the laws themselves came about we have to merge the two ideas. The ordinary laws of physics, too, can evolve and therefore they become part of the state.

This is a philosophical can of worms. An ordinary person like myself would not waste 5 minutes thinking about it. But if you want to do some nontrivial PoS, I think you have no choice. You must address the issue of why these laws? and how they might have evolved.
That's my feedback.

tvolpe

Thank you for all the feedback it and the links have been tremendously helpful.

While it may not be exactly a how I latter go on to attempt to theorize that all these fields establish a field of conscious that allows the becoming-in-itself (the totality of scalar fields) to be conscious of its individual constituents or particles. This field of conscious is what allows for the construction of what I term assemblage, which are basically anything physical that we can turn into a system (i.e through phenomenological observation of these assemblages scientist turn them into models that allow humans to understand their nature.) Does that sound like i'm at least on the right track even if not at the starting gates? Sorry, outside of some Carl Popper and Bertrand Russell as an under grad I am not particularly literate in PoS, my work and studies have focused more on human consciousness. I was attempting PoS to try and better place humanity with and within its place in the universe.

Also earlier in the work try to hypothesis that dark energy is a quintessence field made up of strings that were originally pushing our two cosmos apart, but that this was at some point limited and stopped at which time it began using it pent up energy to inflate the Higgs field or latent plane of immanence leading the the acceleration of space we see today. While non-baryonic dark matter is the gravitational effect of the matter in our sister cosmos that is felt because the plane of immanence (gravity) can transcend all dimensions or is a closed string. I do this because the two seem to somewhat challenge (at least dark matter) my field of conscious agreement, is this a completely illegitimate hypothesis?

tvolpe

marcus, I have found a tremendous amount of information in the link you sent me that is beginning to answer many of my question and speculations. It looks like I'll have a couple hundred pages of brilliant reading over the next couple of weeks. I cannot thank you enough for your time and comments.

Kindest Regards,
trv

LouisB

I like the defintion of the universe as "everything that exists". The laws of nature , the mathematics used in these law, everything has to be inside of the universe. This definition preclude any outside to exist.