"But some of the greatest achievements in philosophy could only be compared with taking up some books which seemed to belong together, and putting them on different shelves; nothing more being final about their positions than that they no longer lie side by side. The onlooker who doesn't know the difficulty of the task might well think in such a case that nothing at all had been achieved." -Wittgenstein
One of the most fundamental questions about the Universe that anyone can ask is, "Why is there anything here at all?"
Image credit: Patrick at vignetted.com.
Out beyond Earth, of course, there are trillions of other worlds within our own galaxy, and at least hundreds of billions of galaxies within just the part of our Universe that's observable to us.
Image credit: NASA, ESA, S. Beckwith (STScI) and the HUDF Team.
Explaining where all the matter in the Universe comes from is one thing. What you traditionally think of as something -- that is, the plants, animals, elements, planets, stars, galaxies and galaxy clusters -- that's one question.
How and when all of that got here? That's something we think we can answer.
Image credit: me, as a New Year's present to you.
But there's an even more fundamental question than that. In order to have our Universe, you need to start with what, as a physicist, I call nothing.
You need to start with empty spacetime.
From a physical point of view, that's what nothing is. Only, perhaps perplexingly, that zero-point energy? It isn't zero.
Image credit: Brian Greene's Elegant Universe.
If it were, we wouldn't have a Universe filled with dark energy, and yet we do. Instead, spacetime has a fundamental, intrinsic, non-zero amount of energy inherent to it; that's what's causing the Universe's expansion to accelerate! What's even more bizarre than that is the fact that all the matter and energy in the Universe today came from a drop, long ago, from an even higher zero-point-energy state. That process -- reheating -- is what comes at the end of an indeterminately long phase of exponential expansion of the Universe known as cosmic inflation.
Image credit: Ned Wright.
The regions of space where this drop in zero-point energy occurred gave rise to regions of the Universe like ours, where matter and energy exist in abundance, and where the expansion of spacetime is relatively slow. But the regions where it hasn't yet occurred continue to have an extremely rapid rate of expansion. This is why physicists state that inflation is eternal, and this is also the physical motivation for the existence of multiverses.
In the diagram below, regions marked with red X's are regions where the drop in zero-point energy occurs, and a region of the Universe like ours comes into existence.
Image credit: me, created especially for you last year.
That's the physical story of where all this comes from. Of where our planets, stars, and galaxies comes from, of where all the matter and energy in the Universe comes from, of where the entire 93-billion-light-year wide section of our observable Universe comes from.
From a scientific perspective, we think we understand not only where all of this comes from, but also the fundamental laws that govern it. So when a physicist writes a book called: A Universe from Nothing, I know that some version of this story -- the scientific story of how we get our entire Universe from nothing -- is the one you're going to get told.
It's a remarkable story, it's perhaps my favorite story to tell, and it's certainly been the greatest story I've ever learned. But in at least one way, it's a dissatisfying story. Because the scientific definition of "nothing" that we use -- empty, curvature-free spacetime at the zero-point energy of all its quantum fields -- doesn't resemble our ideal expectations of what "nothing" ought to be.
Image credit: retrieved from Universe-Review.ca.
No one sufficiently versed in the science of physical cosmology (and being sufficiently honest with themselves about it) would argue against this: that the entire Universe that we know and exist in comes from a state like this, that existed some 13.7 billion years ago. But you may rightfully ask, "Is that truly nothing?"
This empty spacetime definition of what is physically nothing stands in contrast to what we can imagine as what I'll call pure (or philosophical) nothingness, where there's no space, no time, no laws of physics, no quantum fields to be in their zero state, etc. Just a total void.
It is a remarkable story, of course, and it explains where every galaxy, every star, and every atom in the Universe comes from, an astouding feat.
Image credit: Don Dixon.
But it doesn't explain, existentially, why spacetime or the laws of nature themselves exist, or exist with the properties that they have. In short, understanding how something comes from nothing does not explain how this physical state of nothing comes from an existential nothingness. This question of why, as enunciated by Heidegger, is not addressed by our physical understanding of the Universe. But is it a fair question?
Like the oft-dismissive Wittgenstein, I'm not sure. We make this inherent assumption that both spacetime and the laws inherent to our Universe come from somewhere. Yet our classical notions and intuitions about causality are violated even within our known Universe; do we have good reason to expect that this non-universal form of logic applies to the very existence of the Universe itself? Furthermore, how can something, even figuratively, come from anything else if you remove time?
One can, of course, imagine answers to these questions: an entity of some sort that exists outside of time and thus has access to all times equally, a type of hidden-variable logic that exists as part of reality but requires the knowledge of things that are presently unobservable to us, a higher-dimensional being who sees our entire Universe no differently from how an animator sees the elements of a two-dimensional cartoon, etc.
Image credit: Chuck Jones / Warner Brothers Studios.
None of these answers are convincing or compelling, mind you, and I am not sure that the questions do even make sense as far as reality is concerned. But just because we cannot yet know the answers, or whether the questions are sensible as far as reality is concerned, doesn't mean there isn't value to asking them and thinking about them. To me, that's what philosophy is. I would encourage everyone to remember the words of my favorite philosopher, Alan Watts:
The reason for it is that most civilized people are out of touch with reality because they confuse the world as it is with the world as they think about it, talk about it, and describe it. On the one hand, there is the real world, and on the other, a whole system of symbols about that world that we have in our minds. These are very very useful symbols -- all civilization depends on them -- but like all good things, they have their disadvantages, and the principal disadvantage of symbols is that we confuse them with reality.
For whatever it's worth, when I think of nothing, I think about empty spacetime and the physical Universe: that's where my interests lie, and that's where I believe the knowable lies. But that doesn't mean there isn't something wonderful to be gained from philosophizing. As Alan Watts himself said:
And as well as this explanation actually describes what I think about the Universe, it didn't come from a physicist. So let's stop accusing each other -- physicists and philosophers -- of being bad at one another's disciplines, and let's work on getting it right. Education is always worth it.
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Great post,
It's great to hear this debate is happening, I'm not up to date on where people are but it's fascinating and I think it's important too. I'll have to read through the links you listed about the debate.
As physics get better at explaining the world it also seems to get stranger and I think the general public is feeling left behind on understanding it all. Most people don't really care or need to know all the details but this fundamental question of where Everything comes from and Why is much more important to most people than whether we can explain 16 billions into the past or not.
I think there is an answer there waiting for us that can satisfy both physics and philosophy each in their own way.
Wittgenstein is interesting, you know there is a little book of Alan Turing wherein there is a debate with him. As I am a skeptic about the safety of the LHC I like to refer to their debate:
W: ... where will the harm come?
T: The real harm will not come in unless there is an application, in which a bridge may fall down or something of that sort.
W: ... The question is: Why are people afraid of contradictions? It is easy to understand why they should be afraid of contradictions, etc., outside mathematics. The question is: Why should they be afraid of contradictions inside mathematics? Turing says, 'Because something may go wrong with the application.' But nothing need go wrong. And if something does go wrong â if the bridge breaks down â then your mistake was of the kind of using a wrong natural law. ...
T: You cannot be confident about applying your calculus until you know that there are no hidden contradictions in it.
http://www.turing.org.uk/philosophy/ex4.html
And as empty space is not just empty ... and so on ... well, high-energy collisions at the same spot, far beyond the frequency of cosmic rays at a specific place in space & time, might shake up a whole lot more in the void and its surroundings, than is understood.
btw for those who do not know what Alan Turing looks like, check out this image : P
http://parrolo.deviantart.com/art/Alan-Turing-Centenary-291397916
I wanted to thank you for this post. I'm a philosopher, and I have loved reading your blog for some time now. There seems to be so much contention between some from both of our professions, but I hold that all of our colleagues are seeking the same truth, albeit using different methodology. Thank you again. Keep up the good work.
"well, high-energy collisions at the same spot, far beyond the frequency of cosmic rays at a specific place in space " Hah?
The collisions at the LHC are far from at the same spot. In fact that is where most of the cost has gone, trying to at least get them close enough that we can have some decent number of collisions inside the detectors. But just because on the human scale they are in a circumscribed area, t the scale of the collisions/interaction they are galaxies apart. In fact the collisions are greater than an order of magnitude farther away from each other than, say, galaxy's and their collisions. They are so far away from each other on the scales that they occur that they are essentially independent. We know that because we make very precise predictions that would be off by a very detectable amount if it was in fact the case that a collision of protons (or rather quarks and gluons or other virtual interaction) could affect an independent set of collisions in an unpredicted way. That would actually be a wonderful thing to see.
So when you make that quoted statement you are at the wrong size to have doubts. The frequency of collisions in a "particular area of space" that makes any difference to the collision is the same in the LHC as in a Super High Energy Cosmic Ray - one thousands of times more powerful than the LHC - One collision in any area of space.
So your doubt on this is implying some natural law exists that we don't know about now, that is undetectable and shows essentially zero effects and has no relation to other natural laws, and it only shows up when things that aren't necessarily even causally related happen "near" each other, for a definition of near that might as well be the size of the universe, (there is no evidence otherwise).
It could be, but one could argue the exact same thing with the same evidence that putting all those electrons together along with positive quasiparticles in integrated ciruits in you computer in a small area unlike anything else we know in the universe could cause spacetime to warp out of shape and cause dire consequences.
âEmpty space ⦠From a physical point of view, that's what nothing is.â
That is just so wrong â I have no idea how you, while understanding some general relativity after all (space being something with properties that can bend and all that), can uphold such a view. It is wrong on several levels, whether it is QM (groundstate of what system?) or emergence of space-time (e.g. string membrane proposals), and more. If you want to say that you, as used in this post, define ânothingâ that way, that would be fine, but âFrom a physical point of viewâ it is, sorry, naïve. You want to make a âdualisticâ distinction between âtruly nothingâ and âphysically nothingâ (that may fundamentally why you and so many otherwise clever people go so very astray), I get that, but a particular physical system just is not âphysically nothingâ, regardless of how one feels about âtruly nothingâ. That second aspect you need to think very much harder about, especially as you quote Wittgenstein often. Different interpretations exist, but as long as you talk about âtruly nothingâ, you do not get Wittgenstein. He is what is missing from the whole debate today - people do not get him at all, but as I pointed out, in this way, the discussion is no more than 'much ado about nothing':
http://www.science20.com/alpha_meme/why_there_something_rather_nothing_…
(thank you for the link, but I think this one would have been much more fitting)
@5 - Markk
Circumscribed, in nature there are about a thousand cosmic-ray collisions of a few GeV's (1 GeV= 10^9 electron Volt) per second per m^2. In LHC it are about one 1 billion per second per cm^2. That's 1.000.000 times more for a surface which is 10.000 smaller, a density difference of 10 billion.
This year humans are going to generate collisions that are 1000 times more intense, with energies of 8 TeV (1 TeV= 10^12 eV). These collisions are in nature even less frequent per m^2 while the frequency at the LHC of 1 billion per cm^2 is maintained.
The LHC is something like a magnifying glass where more and more collisions get to be packed into one condensed spot in time and space, while in nature it is more of a varying low density rainy flow.
Now if the void was real empty space than what you are saying is correct, it all are little quanta that "are galaxies apart", but the fact of the matter is that there IS a fabric like Ethan philosophise about, and it might get to be more and more excited at such high frequencies and densities, that it hasn't got the time to relax and it might start having the effects of a loupe that also bundles small energy quanta (photons) into one focus point to start a combustion process in the matter on which it is aimed at:
http://tinyurl.com/concentrate-collisions
Actually what does distance in space means when you do the double-slit experiment and the photons get to feel the 2nd slit that is relatively a "galaxy apart" or "on the human scale" a few millimeters away?
---
Now safety experts also like to wave with Ultra-high-energy cosmic rays of 10^20 eV, but these events are very rare. They happen only a few times a year and over the whole surface of the earth, and we hardly have a clue of what these events are, who says that they aren't one of "the hidden contradictions" that Turing is talking about?
I think Plato (S. V BC) through "Allegory of the Cave", express better the dilemma you want to set up. I mean Philosophy (Form theory, Ideas, the knowlwdge "supremacy" of everything, Epistemology, very close to mathematics according to R. Penrose) vs Physics (phenomenological world, percepcion Universe, meassurement and experiments, "real", via empirical falsification issue according to K. Popper).
So Physics could never explain why we have certain Physics laws, where everything comes from, etc...it is only limited or condemned to explain it (i.e. evolution with time of all physicals parameters,... BUT one time the mass-energy-space-time is set up by some "Idea" or superior Form Theory...)
http://en.wikipedia.org/wiki/Allegory_of_the_Cave
Thank goodness. From the title, I thought this might be about those ethical intuituion problems like "You can save five people but you have to kill two others and donate their organs and have public sex with a cardboard cutout of a relative". Something from nothingness? Difficult to think about, yes, but no pain yet for this primate's brain. (I admit I'm not thinking about it very hard, though.)
Thanks Ethan
I need to reread this again; all of it including links.
My problem is that I am understanding the words and can parrot them; but I am missing something key to understanding (in particular inflation). So I'll reread and think and try to clarify my question.
And By the way, my understanding of inflation has moved from thinking it is nonsense (a convenient fudge) to a necessary and really interesting idea. So I'm not sure what I'm struggling with. In part it may be context.
Let me talk nits for a second.
@6 Sascha's remark seemed a bit harsh and his link not very useful to the discussion. Though usually Sascha brings a deep insight. I can't find it today.
Which brings me to my nit; which is related.
You say, "You need to start with empty spacetime." and I want to shout No.
But then you go on to show Brian Greene's image; which shows that physics doesn't start with the mathematician's empty spacetime; but rather a physicist's spacetime in which spacetime in an integral part of the concept of what we mean by objects, whether they are real or virtual, classical or quantum, rocks or quarks.
So my wanting to shout No; is a nit because
1) basically, I think that I'm agreeing with you
2) "nothing" is not the concept that I am struggling with to understand today
3) as you say, "It's supposed to hurt to think about it!" and the concept that it hurts me to think about (today) is inflation and the philosophical references. so thanks for that hurt.
Which brings me to the book, How is Quantum Field Theory Possible? by Sunny Y. Auyang. She tries to take a proper philisophical view of quantum field theory. She is a physicist. From the first paragraph of her book, "Quantum field theory is the union of quantum mechanics and special relativity. It is our most fundamental theory.. However, its philosophical significance has been largely ignored, although relativity and quantum mechanics have separately simulated much reflection." I can only vouch for the first 15 pages so far.
My point about the above book is that I really appreciate you Ethan bringing in all of the philisophical references; because I think they are really important as we (I) try to understand inflation.
And no I still haven't asked my questions yet; because I can't formulate them yet.
Thanks Ethan as who would have thought it would be so challenging to be left with nothing to think about. Then again there are entities in science which we take to be literally as nothing that stand for potentials which in themselves appear to be merely abstractions of something else. The thing Iâve often wondered which is the more real, that is fundamental, the things we find which are acted upon or the potentials which drive them in their action.
âThus Descartes was not so far from the truth when he believed he must exclude the existence of an empty space. The notion indeed appears absurd, as long as physical reality is seen exclusively in ponderable bodies. It requires the idea of the field as the representative of reality, in combination with the general principle of relativity, to show the true kernel of Descartes' idea; there exists no space "empty of field".â
-Albert Einstein, âRelativity: The Special and the General Theoryâ, Crown Publishing (fifth edition, 1954)
Best,
Phil
@5 - Markk
This one just came to mind in regards to pushing electrons to the limit and how hard we can go:
"... a leader of a bolt of lightning can travel at speeds of 220,000 km/h (140,000 mph), and can reach temperatures approaching 30,000 °C (54,000 °F), hot enough to fuse silica sand into glass." http://en.wikipedia.org/wiki/Lightning
I guess we need to keep the silicon in our computers non-liquid for them to keep on processing, so it is not the exact same thing.
btw the Large Hadron Collider smashed heavy lead ions together at close to the speed of light, generating temperatures of more than 1.6 trillion degrees Celsius, 100,000 times hotter than the center of the Sun, also not exactly the same thing.
Well put, Ethan: I see you are philosophically literate in a way that, say, Krauss is not! Indeed, the "physical vacuum" is not "nothing" in the sense of nothing at all, and leaves unexplained why we have these laws etc. Thanks too for saying "philosophy" has some value, and not making fun of it. (It is hilariously the case, those who ridicule philosophy the most, clearly need competency in it the most!)
And for those who say, this universe (or even a set of defined properties, rather than the entire "every possible model" of Modal Realism and MUH) is "just here" - sorry, that violates the existential principle of sufficient reason. It does not provide an answer: why does one (or some) "possible worlds" really "exist" in the substantial sense that we feel is "more real" than just "an idea", but other PWs do not?
I have to lay out the letdown, that there really *cannot* be a purely logical explanation for existential selectivity if it happened. ES requires some special extra character outside of math, to "breathe fire" into some models and not others. It would be like saying, the number 137 (inside joke) has a special "ghost" inside it that makes it become "real" and not "just a number." Math and logic do not and cannot contain such extra features! So any "reason why" our universe exists, has to be "mystical" unless all of them can exist. (Sorry, I have picked up the philosophers' habit of indulging in quoted words and phrases to make the point when they are questionable.)
Maybe we just can't get it. Nothing: it's a blank thing, you wouldn't understand!
I like word games as much as anyone. I love words. What I have most trouble with is playing games with words and confusing the words with reality. Nothing is a word that I always thought had a meaning like "the absence of everything" But so-called cosmologists like Krauss, Brian Greene, and many others use it and then say "but it doesn't really mean "Nothing", What is the point of this? If there is something out there out of which everything initially arose, "big bang" or whatever, say so and don't play quasi-mystical with your readers. Does "nothing mean there are no "particles"? Does it mean there is no energy field? "Zero Point" is used to say "not quite zero". So what is real and what is just word games?
Charles, a good point in general, and there is an answer based on the way physics works. Many people used to think, empty space was "really nothing". But then we realized that a given dimensionality, the curvability of space-time, the laws being embedded "in space" (from e.g. the virtual particles that are manifested), etc'; means that our "space" is really a physical manifold and doesn't really deserve to be called "nothing".
The universe can't really "come from" a "real nothing" for the latter is not any kind of substrate at all. So when some physicists say the universe can CFN, they either really mean: from a pre-existing physical vacuum, or else they are not clear thinkers. If the universe needs no explanation, then it just "is", and if there is an explanation, that explanation derives from some actual basis or other reality; mystical or mathematical or phenomenal as may be. "Nothing" indeed has nothing to offer, at all.
PS, Ethan, pls. have "remember personal info" button.
ya bi siltir tipe bak gavat
QUESTION, possibly a very stupid one.
In the picture at the very top of the "Universe in One Year" graphic, the little cubes with red Xes on them are experiencing events.
If they experience an event that gives them a red X, the rest of the graphic follows.
Now, here's my question - the only way I can understand those cubes is to conceptualize them as existing in spacetime. What is happening to them in the picture is highly analogous to embryonic development. You start with one cube, then the number of cubes increases, and goes on increasing. As the cubes increase, also, simultaneously, they are committed to various different, more differentiated fates.
But embryoes develop in space and time.
If there is no time, how the hell can you "go from" one cube without red X to more cubes, some which get red Xes and drop out of cubeland to become universes? If there is no time, all cubes must exist simultaneously in all possible states. Yet some of them develop "Red X" state and go on to a differentiated fate, and others do not.
Apologies in advance if this is a moronic question.
I am not a physicist but I am familiar enough with very, very basic relativity to understand that sometimes things that make perfect sense when you look at equations do not make sense when expressed in words or diagrams. Perhaps that is what is happening here.
"If there is something out there out of which everything initially arose, "big bang" or whatever"
Before spacetime, there was no space and, more importantly here, no time.
So what does "before" mean? It's a meaningless question.
Therefore putting "something" into which the Big Bang from which space and time were formed is both pointless and unsupported.
Therefore not done.
Pose this problem for yourself to illustrate why senseless questions only confuse.
Walk to the North Pole.
Stop.
Now Walk North from there.
Which direction do you go?
Neither physics nor any nature science for that matter can discuss "Nothingness" in it's purest form (or as close as we mortals can come to it). Simply because they need "something" in order to work. And in case of physics it's spacetime. Spacetime is something that physics can't be without. Take that away, and you have no physics. Just like if you take away living things, you have no biology.
Only logic and philosophy can try to peer and discuss absolute "nothingness", if it even exists.
So I have to agree and disagree with the statement that "before" BB or inflation is a meaningless question. Yes, it's meaningless from physics standpoint. But it's valid from philosophical point. Our imagination is not bound by physics (ok, maybe it is in some QM sense :D ), but never the less... it's a valid question, just not for physics. After all we can imagine in our brain a void without space and time. The problem... we can't imagine our own Self not existing. So it's not "nothingness" in it's absolute form.
"Spacetime is something that physics can't be without."
Actually, laws can still exist even if there's nothing for it to operate on.
If you're an Object-oriented programmer, spacetime is the instantiation of the class of physics that we call reality. But the class definition exists before the instantiation, and has nothing to do with the operation or even operability of the class members.
You still need to consider what you mean by "before" since in english it is inherently aligned to a time dimension.
Just like "North" is aligned to an axial one on a rotating sphere's surface.
Before the big bang? Do you mean the laws that existed that allowed a time and space to exist as this one does?
No time needed.
No space needed either.
But "Nothing" in a universe of spacetime with our current laws of nature is not empty of everything.
A "nothing" without a universe of spacetime is not empty since it occupies no space. And it doesn't turn into something.
per @10 above, I've come to accept inflation. However I have some big picture questions.
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I use "UNIVERSE" (upper case) to represent everything (i.e. all multiverses) and "universe" (lower case) to represent our visible universe (i.e. our 1 multiverse).
question 1)
Are some multiverses in the UNIVERSE inflating and others deflating? or Are all multiverses in the UNIVERSE inflating? and thus Why can multiverses not deflate?
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wiki gives three possible reasons for Baryon asymmetry in our visible universe.
1)CP violations
2)Regions of the UNIVERSE(my upper case) where antimatter predominates
3)Electron dipole moment
Question 2)
Does any inflation work consider antimatter multiverses?
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Question 3)
What is the relation between inflation and black holes, white holes and worm holes?
"Could our universe be located within the interior of a wormhole which itself is part of a black hole that lies within a much larger universe?" http://www.sciencedaily.com/releases/2010/04/100406172648.htm http://arxiv.org/pdf/0901.0215v1.pdf
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Thanks for any discussion, insights, or opinions about these questions.
"Why can multiverses not deflate?"
I don't know of any theory of multiverse that forbids them deflating.
"Does any inflation work consider antimatter multiverses?"
They would be, by definition, matter universes. Just not one you'd like to visit.
"What is the relation between inflation and black holes, white holes and worm holes?"
Almost definitely None. Mostly because they're different phenomena.
White/black holes and a wormhole between them are a consequence of one mathematically plausible scenario of GR.
Inflation is observed and another plausible, but independent, mathematical scenario of GR.
White holes as a counterpart to black holes are a consequence of the second law of thermodynamics applied to the mathematical expression of GR on a black hole: Hawking radiation quick enough to explosively reduce a black hole to nonexistence, but aren't necessarily another end of a wormhole.
The idea of a universe in a black hole is that when you get a singularity, the physics and matter now change qualitatively rather than merely quantitatively. You get a singularity COULD be like getting a new universe.
My problem with it is that this universe is fed from infall from that other "higher" universe therefore should see continuous creation.
I.e. not like ours.
@20 Wow
"If you're an Object-oriented programmer, spacetime is the instantiation of the class of physics that we call reality. But the class definition exists before the instantiation, and has nothing to do with the operation or even operability of the class members."
Hmmm.. interesting analogy, but I would have to disagree on one important issue. Spacetime is not the instantiation of the class of physics. Spacetime is the programing language itself. It is that in which everything exists. And the laws of physics are classes, procedures and routines. They can not exist outside of the programming language, just as laws of physics can't exist outside of spacetime.
"Before the big bang? Do you mean the laws that existed that allowed a time and space to exist as this one does?"
Well... no, not exactly. It's not about BB, it's about the "Nothingness"... And it's not a physics question, it's a logical one. I don't mean anything by that, only that physics can't answer. Maybe nothing can. Because if you postulate some "previous" set of laws.. or anything for that matter, then it's not nothingness anymore. It was something that somehow made this "something" we call reality. But if you had "absolute" nothingness, then no laws existed, and there is no way to have this "something". Even if you postulate God in this nothingness, it's allready something... God. So like I said in a previous post. Am not sure "absolute" nothingness can even exist, even as a thought.
But something else just crept in my brain. And is partially linked to this and partially to OKThen's question.
If we look at a multiverse and universes in it as "standalone" entities (like bubles in soda water, like so many physicists like to illustrate). What is that which is "between" them. What is the analogy to water in soda water? Is it spacetime... but different than our spacetime. Or is it "nothingness"? Meaning absolute nothingness as in no quantum fluctuations of spacetime.. no nothing?
"Spacetime is not the instantiation of the class of physics. Spacetime is the programing language itself"
Only necessarily the programming language as implemented by the class instantiated.
Think of Langton's Ant.
Apparently it has a few laws that emerge if all you can see are the patterns.
Stage 1: Simple pattern
Stage 2: chaos
Stage 3: Repeated ladder pattern that moves
But these emerge from the law of the Ant, but are not known to be inherent to those laws. A particular arrangement may show another stage, or break one of those three stages.
Ever created your own compiler? You describe the rules and implement them, but the language you created aren't defined by your YACC code, merely how you instantiated them to your FooLang.
"What is that which is "between" them."
Genuinely nothing? I.e. no spacetime whatsoever.
The problem is our words are freighted with inherent meaning (and why most theoretical physics can only be "correctly" expressed in mathematics which carries much less of this baggage).
Between. Infers that there is some substance separating them.
But before the idea of the colourless gas "air" was considered, we had separations between things that consisted of "nothing". Nothing between the flying bird and the ground, it just flies there.
Our thinking is more sophisticated, but I would say is making it harder to move away from inferred reality.
Ethan:
@24 Wow
"Think of Langton's Ant."
Are you sure that's a good example. It needs a grid, needs spacetime. Without the grid it doesn't exist. Or any cellular automaton...
Maybe my reference to a computer language was bad. The computer itself would be spacetime, as the computer language is "in" the computer.
"Between. Infers that there is some substance separating them."
doesn't need to be any substance... but separation yes. I'm not a physicist nor a mathematican, so the math dealing with multiverse is beyond me. But am genuinely interested how math describes it. Is there separation between them or are they "stuck" to one another.. like i.e. soap foam?
Our math and laws of physics are sort of stuck inside our universe, and can't go outside of it. But our minds can. That's why I'm curious :)
If I may jump into this "Nothing" discussion.
In Newtonian physics, space and time were absolute, meaning that physicists took a god's eye view of the universe. Of course such a absolute god's eye view is not a humanly possible viewpoint. As well, in classical physics nothingness, the physical vacuum, is absolute in a god's viewpoint sense as well. But the human vacuum was never anywhere near the absolute nothingness of classical physics.
When we compare classical physics to quantum physics, we often suggest that classical physics makes common sense; whereas quantum physics (and relativity as well) is nonsensical or paradoxical.
We forget that classical physics was not obvious to human senses. The world appeared flat and man's psychological world (e.g. imagination, dreams, hallucinations)appeared supernatural.
Classical physics correctly stripped away the errors of pre-scientific understanding of the world. But it wrongly stripped away self from the "idea" of world.
And further, the success of classical physics has been so great that today most people consider classical physics to be "common sense".
But classical physics could never fully banish common sense from science. Because the language of words, mathematics and physics can not function without common sense.
Classical physics obviously depended upon the senses (and instruments) for observations and common sense for interpretation. But classical physics was a very idealized, rigid and absolute world from a god's eye view.
The human observer was a redundancy to be eliminated in classical physics speak. But this violated both sense and common sense. Everyman knew that man was part of this world, influencing, shaping, limiting it in however small but real human way.
In this fundamental way, common sense was more realistic than classical physics. Thus in that sense, classical physics used the repertoire of common sense to interpret and make sense of classical physic theory. But classical physics did not use the full repertoire of common sense. The necessity of taking account of the individual human was righteously neglected by classical physics.
Quantum mechanics (and relativity) corrected this biased neglect of classical physics. Both FORCED physice to admit the common sense idea that the individual person made a real difference in limitation to what is knowable from an individual and particular reference point. These are common sense elements that were neglected by classical physics but can not be neglected by modern physics.
Much of what I've just said, I wouldn't have said a week ago before I began reading How is Quantum Field Theory Possible? by Sunny Y. Auyang @10 above.
To quote her again, "The existing condition of the quantum world brings out the power and limitation of human capabilities. Like a man who... comes to know himself, quantum field theory illuminates not only elementary particles but also ourselves... situated.. within the world instead of an absolute view from without.. It takes account of.. the finitude and reflexity of our knowledge and observation... the framework of things is logically equivalent to the phenomenological framework.. which codifies phenomenon (things) as the only "scientific" framework.. but it has thrown away the necessary supplement of common sense. Thus such scientism is rigid and.. deeply prejudiced.. while proclaiming its.. supposedly unbiased view." pages 8-10
Now back to "nothing". The "nothing" of classical physics was a pure and absolute idea which was a mathematical extrapolation of experience to infinity. Such extrapolations are outside of man's primitive common sense. They are in 21st century man's "common sense" only because we have been taught well and learned well the ideas of classical mathematics and physics.
But our common sense is a biological heritage which allows us to understand reality better from our limited human point of view than from a rigid classical absolute god's eye point of view. Fortunately, in some ways quantum mechanics and relativity are closer to a primitive human point of view than a god's eye point of view.
Now back to "nothing". There is nothing like Newton's absolute "nothing" in the real world or in the primitive human's view of the world. Thus our primitive instrument of common sense is able to incorporate and operate upon the notion of quantum nothingness with no more problem than it had dealing with Newtonian nothingness. But first we must let go the rigid idea (fabulation) of absolute Newtonian nothingness; whose only merit and sense was that it was hypothesized to match the real world. Now we have quantum relativistic spacetimes which are closer approximations to reality and whose quantum vacuum of nothingness is no more difficult to understand than the preclassical nothingness of dreams and spirits and hallucinations.
Throw away the classical idea of a vacuum and instead take the solid state physicists idea of a vacuum. It is teaming with stuff. Why? Because the definitions of spacetime matter energy are hopelessly intertwined. we cannot define one without the other; anymore than we can define world without the idea of self.
Since classical nothingness is not necessary for common sense; we can dispense with it and many of the addendant paradoxes like Aesop's turtle and hare dissappear as non sequiturs.
In the diagram where it says "indeterminate duration" is there a restriction that the duration be finite? Aka, does this model of cosmology allow for the multiverse to be eternally pre-existent?