Last week I spent an enjoyable few days in Tenerife, one of the Canary Islands, for a conference on the Philosophy of Cosmology. The slides for all the talks are now online; videos aren’t up yet, but I understand they are forthcoming.
It was a thought-provoking meeting, but one of my thoughts was: “We don’t really have a well-defined field called Philosophy of Cosmology.” At least, not yet. Talks were given by philosophers and by cosmologists; the philosophers generally gave good talks on the philosophy of physics, while some of the cosmologists gave solid-but-standard talks on cosmology. Some of the other cosmologists tried their hand at philosophy, and I thought those were generally less successful. Which is to be expected — it’s a sign that we need to do more work to set the foundations for this new subdiscipline.
A big part of defining an area of study is deciding on a set of questions that we all agree are worth thinking about. As a tiny step in that direction, here is my attempt to highlight ten questions — and various sub-questions — that naturally fall under the rubric of Philosophy of Cosmology. They fall under other rubrics as well, of course, as well as featuring significant overlap with each other. So there’s a certain amount of arbitrariness here — suggestions for improvements are welcome.
Here we go:
- In what sense, if any, is the universe fine-tuned? When can we say that physical parameters (cosmological constant, scale of electroweak symmetry breaking) or initial conditions are “unnatural”? What sets the appropriate measure with respect to which we judge naturalness of physical and cosmological parameters? Is there an explanation for cosmological coincidences such as the approximate equality between the density of matter and vacuum energy? Does inflation solve these problems, or exacerbate them? What conclusions should we draw from the existence of fine-tuning?
- How is the arrow of time related to the special state of the early universe? What is the best way to formulate the past hypothesis (the early universe was in a low entropy state) and the statistical postulate (uniform distribution within macrostates)? Can the early state be explained as a generic feature of dynamical processes, or is it associated with a specific quantum state of the universe, or should it be understood as a separate law of nature? In what way, if any, does the special early state help explain the temporal asymmetries of memory, causality, and quantum measurement?
- What is the proper role of the anthropic principle? Can anthropic reasoning be used to make reliable predictions? How do we define the appropriate reference class of observers? Given such a class, is there any reason to think of ourselves as “typical” within it? Does the prediction of freak observers (Boltzmann Brains) count as evidence against a cosmological scenario?
- What part should unobservable realms play in cosmological models? Does cosmic evolution naturally generate pocket universes, baby universes, or many branches of the wave function? Are other “universes” part of science if they can never be observed? How do we evaluate such models, and does the traditional process of scientific theory choice need to be adapted to account for non-falsifiable predictions? How confident can we ever be in early-universe scenarios such as inflation?
- What is the quantum state of the universe, and how does it evolve? Is there a unique prescription for calculating the wave function of the universe? Under what conditions are different parts of the quantum state “real,” in the sense that observers within them should be counted? What aspects of cosmology depend on competing formulations of quantum mechanics (Everett, dynamical collapse, hidden variables, etc.)? Do quantum fluctuations happen in equilibrium? What role does decoherence play in cosmic evolution? How does do quantum and classical probabilities arise in cosmological predictions? What defines classical histories within the quantum state?
- Are space and time emergent or fundamental? Is quantum gravity a theory of quantized spacetime, or is spacetime only an approximation valid in a certain regime? What are the fundamental degrees of freedom? Is there a well-defined Hilbert space for the universe, and what is its dimensionality? Is time evolution fundamental, or does time emerge from correlations within a static state?
- What is the role of infinity in cosmology? Can the universe be infinitely big? Are the fundamental laws ultimate discrete? Can there be an essential difference between “infinite” and “really big”? Can the arrow of time be explained if the universe has an infinite amount of room in which to evolve? Are there preferred ways to compare infinitely big subsets of an infinite space of states?
- Can the universe have a beginning, or can it be eternal? Does a universe with a first moment require a cause or deeper explanation? Are there reasons why there is something rather than nothing? Can the universe be cyclic, with a consistent arrow of time? Could it be eternal and statistically symmetric around some moment of lowest entropy?
- How do physical laws and causality apply to the universe as a whole? Can laws be said to change or evolve? Does the universe as a whole maximize some interesting quantity such as simplicity, goodness, interestingness, or fecundity? Should laws be understood as governing/generative entities, or are they just a convenient way to compactly represent a large number of facts? Is the universe complete in itself, or does it require external factors to sustain it? Do the laws of physics require ultimate explanations, or can they simply be?
- How do complex structures and order come into existence and evolve? Is complexity a transient phenomenon that depends on entropy generation? Are there general principles governing physical, biological, and psychological complexity? Is the appearance of life likely or inevitable? Does consciousness play a central role in accounting for the universe?
Chances are very small that anyone else interested in the field, forced at gunpoint to pick the ten biggest questions, would choose exactly these ten. Such are the wild and wooly early days of any field, when the frontier is unexplored and the conventional wisdom has yet to be settled. Feel free to make suggestions.
I guess I dont understand why many of these questions should involve philosophers at all. Surely for instance the fine tuning question is a matter of experimental science, and essentially is well defined theoretically and has been for over thirty years. It’s not clear to me what utility a philosophers opinion is going to bring to this problem.
In my experience this is especially true in very fluid areas of physics, as most philosophers are better at dealing with mature subjects where things have settled down a bit. Here for instance many of these questions will go away or be altered if we measure a zero value for the cosmological constant (or find another explanation for dark energy), or if we measure that the electroweak vacuum is radiatively stable (or say discover new physics at the LHC). There are just too many possibilities and its hard to know how things will turn out.
In regard to part of question 8 “Are there reasons why there is something rather than nothing?”, my proposed solution to the questions “Why is there something rather than nothing?” and “Why do things exist?” is at:
sites.google.com/site/whydoesanythingexist
It’s about 3 pages, but if you don’t want to go the website, a summary is below. Thanks.
Roger
A solution to the question “Why is there something rather than nothing?” is proposed that also entails a proposed solution to the question “Why do things exist?”. In brief, I propose that “something” and “nothing” are just two different words, derived from two different ways of thinking, for describing the same underlying thing: what we’ve traditionally, and, as will be shown, incorrectly, thought of as the “absolute lack-of-all” or “non-existence”. I put these phrases in quotes because I try to show by my argument that the situation we usually think of as “nothing”, the “absolute lack-of-all” or “non-existence” (e.g., the absence of all matter, energy, space/volume, time, thoughts/concepts, mathematical and physical laws, and the absence of all minds to think about this “lack-of-all”) isn’t really true “nothing”ness. That situation itself, and not our mind’s conception of it, meets the definition proposed here of what it means to be an existent entity.
How can this be? To answer that, I first discuss the question “Why do things exist?” and use the example of a pile of dirt. Why does a pile of dirt exist?. Three choices for places that might give existence to the pile of dirt are the stuff inside the pile (e.g., the molecules of dirt), the surface or edge of the pile which defines what is contained within the pile, and something outside the pile. Discussing the last choice first, If the reason for existence for the pile were something external to the pile, one would then have to ask why that external thing exists and then why something external to that external thing exists. To avoid an infinite regress, there would eventually have to be some thing that exists for reasons intrinsic, and not external, to it. Because that would be equivalent to asking the original question of why the pile of dirt exists without considering the external option, l will no longer pursue the external option. So, that leaves two choices for why a thing, like a pile of dirt, exists: the stuff inside the pile (e.g., the molecules of dirt) and the surface or edge of the pile. I argue for the second choice: that it is the surface or edge which gives existence to the pile of dirt. More generally, what I mean by the surface/edge argument is that a thing exists if it is a grouping or relationship that defines what is contained within. This grouping/relationship is equivalent to a surface, edge or boundary defining what is contained within and giving “substance” and existence to the thing as a unit whole that’s a different existent entity than whatever is contained within. Some evidence against the first and third choices and for the second choice include:
1.) Try to imagine a thing like a pile of dirt existing that does not have an outermost edge or surface. Even if you say I can remove the outer layer of the pile and still visualize the pile, then remove the outermost layer of what’s left, and remove the outermost layer of what’s left after that. Eventually, to avoid an infinite regress and to still have anything exist at all, there must be some smallest, most fundamental existent entity that has an outermost surface and nothing further inside.
2.) A thing like a pile of dirt is not just a bunch of dirt molecules considered individually. It’s the grouping together of these molecules into a new unit whole called a pile. The pile is a different existent entity than the individual dirt molecules considered on their own, and it is the grouping/relationship/surface defining exactly is contained within that is responsible for the pile being a different existent entity than the dirt molecules considered individually.
3.) The stuff-inside and stuff-outside arguments both succumb to infinite regress problems. For instance, with the stuff-inside argument, one might ask: what’s inside the molecules of dirt, what’s inside the atoms in the molecule of dirt, what’s inside the protons and electrons in the atoms in the molecule of dirt, etc. At some point, to avoid an infinite regress and to still have anything existing at all, there must be some smallest, most fundamental existent entity that exists that has nothing at all inside. An existent entity with absolutely nothing inside would seem to be just a surface. What else would it be?
In sum, I propose that a thing exists if it is a grouping or relationship present defining what is contained within. This grouping/relationship is equivalent to a surface, edge or boundary defining what is contained within and giving “substance” and existence to the thing.
Next, in regard to the second question, “Why is there something rather than nothing?”, “absolute nothing”, or “non-existence”, is first defined to mean: no energy, matter, volume, space, time, thoughts, concepts, mathematical truths, etc.; and no minds to think about this absolute lack-of-all. This absolute lack-of-all itself, and not our mind’s conception of the absolute lack-of-all, is one and the same as the entirety, or whole amount, of all that is present. It is the entirety, or the all, of what is present (absolute nothing). An entirety/whole amount is a relationship defining what is contained within (e.g. the all, which in this case is “absolute nothing”) and is therefore a grouping, an edge, and an existent entity. In other words, because the absolute lack-of-all is the entirety of all that is present, it functions as both what is contained within and the grouping defining what is contained within. It defines itself and is, therefore, the beginning point in the chain of being able to define existent entities in terms of other existent entities. The grouping/edge of the absolute lack-of-all is not some separate thing; it is just the “entirety”, “the all” relationship, inherent in this absolute lack-of-all, that defines what is contained within. What all of this means is that 1.) our traditional definition of the “absolute lack-of-all” as the lack of all existent entities is incorrect because even after we’ve gotten rid of all things thought to exist, the “absolute lack-of-all” itself can be seen to be an existent entity if thought of in this different way; 2.) our traditional view of “nothing” as the opposite of “something” is incorrect because “nothing” and “something” are really two words for the same thing; 3.) “something” or “existence” is necessary, or non-contingent, because even what we’ve traditionally thought of as “nothing” is actually an existent entity, or “something”; and 4.) the fundamental building block of existence is the existent entity previously, and incorrectly, thought of as “non-existence”.
An additional argument that comes to the same conclusion that “something” and “nothing” are really two different ways of thinking about the same underlying thing is as follows. Consider the question “Why is there something rather than nothing?”. Two choices for answering this question are:
A. “Something” has always been here.
B. “Something” has not always been here.
Choice A is possible but does not explain anything. Therefore, choice B is the only choice with any explanatory power. So, let’s explore that choice to see where it leads. With choice B, if “something” has not always been here, then “nothing” must have been here before it. By “nothing”, I mean the same “absolute lack-of-all” described above. In this “absolute nothing”, there would be no mechanism present to change this “nothingness” into the “something” that is here now. But, because we can see that “something” is here now, the only possible choice then is that “nothing” and “something” are one and the same thing. This is logically required if we go with choice B.
Finally, I use the conclusion that the fundamental building block of existence is the existent entity previously, and incorrectly, thought of as “the absolute lack-of-all” to build a primitive model of the universe via what I refer to as a metaphysics-to-physics approach or philosophical engineering. It is argued that using this type of thinking will provide faster progress towards a deeper understanding of the universe than the more top-down approach that physicists currently use.
Suggestion: Don’t yield so much to philosophy. I think many of these questions may be fundamentally scientific rather than philosophical. Fine tuning, anthropic predictions, etc. may be demonstratable.
On the other hand, dealing with infinity is most likely philosophical.
Just because we don’t know answers today, doesn’t mean a question is philosophical.
Is this a philosophical question:
Is fundamental vs emergent objective in all cases? In mathematics, axioms can be swapped out with other theorems and the same mathematical structure remains. In physical systems, can we regard some ’emergent’ phenomena as fundamental and derive the rest of the physical system (including what we regard as fundamental today)?
@Shriner
I support your argument mostly. So, you owe it to me to check out my ideas.
http://fqxi.org/community/forum/topic/1877
http://www.qsa.netne.net/
My system predicts the mass of the electron naturally, you can play the simulation
http://www.qsa.netne.net/sfemsub.html
This is a great idea…would be great too, to attempt to categorize these (and future) questions and then answer them regardless of the upcoming attempt of a “Philosophy of Cosmology” After all none of these questions are going to go away (or get answered) on their own. The questions grow…even when they answered.
I have not read each of the other posts so I’m hoping that these will be a bit different (I have three that share some similarities):
1) What is matter or things/stuff (that which takes up space…or has inertia…so; what does that mean?). If we know that baryonic ‘matter’ makes up 4% of our reality and that even that (at the atomic level) is 99.99% ‘empty space’ then how can any physical materialistic ‘thingness’ be called reality? How can ‘science’ tell us what is going on when it is missing 96% of all that is? Is it possible that there is no such ‘thing’ as things? That physical matter as we typically understand it…has made it too blasé by the term ‘thing’? And that therefore; nothing exists (no ‘things’ exist)—that all physicality is an electromagnetic projection as if a hologram…and, along with the quantum ‘world’, we truly have little clue just how correct Eddington was when he said the “universe is stranger than you can suppose”. This unfortunately (or now, it is philosophically fortunate), would force materialistic science to reach for a true philosophic meaning…which it seems; it is headed towards anyway. Even E=MC^2 demands that matter (stuff/things) are ‘made-up’ of Energy and light (neither of which has any ‘real’ materialistic physical substance).
2) The unreasonable effectiveness of mathematics (an abstract language) to define a physical universe. WHY? And further how does the manderbroit set (and other fractal geometries) add to this ability of numbers to describe scientific endeavors? If there is infinity then fractal geometry allows for mutation and yet self-similarity…with its never ending mathematical (set) computations, this would help remove the (our) sense of a materialistic physical world…and even time would be twisted. Further is it possible that this ‘math’ is an intelligence that is routed in with the constant stream of neutrinos—sort-of like the refresh rate in a flat-screen 1080dpi TV set? This would add to the idea (in 1 above). Stretching this ‘scary’ idea…could we actually be creatures that reside with-in these Earthsuits…a sort-ta intelligent energy. As long as we are in these ‘suits’ we experience matter, space, and time? OUCH!
3) This fine-tuned thing is getting more interesting (and needs to be figured out) but silly things like the “million monkey theorem” to explain away order and possible deliberate design…is third-gradeish at best. Fractal geometry can describe coast-lines and even clouds; the Fibonacci sequence (plant phyllotaxis) shows an order in life (not to mention DNA). Not all explanations need explanations: if we found a crater on the moon full of junk objects that we could not recognize (but it was clearly a pile of junk) then the answer to whether we are alone in the universe would end (we could tell by the junk that it did not come from Earth…and therefore there must have been an intelligence that was here at some time). If the crater were full of a pile of old Model-A Ford car parts…the problem would be even a greater mystery! ). Allowing chance to get a new lease on life by postulating multiverses is more amazing than philosophy (or religion). One cannot just go moving the goal post further down the playing field when we don’t like that the opposing team has an advantage—there are rules to truth and it is usually centered around (Occam’s Razor): reasonable findings, simplicity in calculations, and beauty in operation and design. We like to complicate ‘things’ (actually expending our energy—wasted intelligence) as entropy exacerbates information further (the expanding universe will eventually isolate us from other galaxies). The Internet has allowed us to communicate now we need to not complicate.
Gordon
I know it might feel like ho hum, but please, check the links above your post, it might make you feel more confident in the final answer.
“Reality is nothing but a mathematical structure, literally”
Why this Universe even exists? Why do we exist? Is there any sense to it all?
QSA
#1. You are off topic.
#2. You are self promoting…not a polite thing to do on someone else s Blog.
#3. I owe you nothing.
#4. I absolutely do not agree with you in any way.
Good luck with your work.
Bob
“Such are the wild and wooly early days of any field, when the frontier is unexplored and the conventional wisdom has yet to be settled. ”
I am humbled by the extend of the unexplored and I hope that it will do so for mankind. I am convinced that new physics is on the horizon. Prof Efstathiou hinted at that at the press conference (March 2014) on Planck results.
With a open mind , we may come to the conclusion that the material is not all that is there. Can a materialistic world view/”conventional wisdom” answer all the questions?
“I really doubt this question would have made the cut without the influence of the creationists and the so called intelligent design crowd. This one is not worth wasting time on.”
While creationists and intelligent-design proponents (note how important the dash in the compound adjective is!) often invoke fine-tuning arguments, the discussion of fine-tuning has a long and respectable history in cosmology which is completely independent of creationism and intelligent design.
Adding to the questions posed by Sean is fairly easy. But to respond otherwise is a handfull.
I think the ancient Greeks pondered around the questions of there time same.
And I think that an uncaused first cause is still relevant today. It is “so logical” that infinite regress is not a position of confidence. One has to then consider the possibility of a entity without beginning, the eternal ( timeless) ultimate source (of metaphysical energy) of everything.
Wil we ever come to grasp the concept of “energy” ?
I have a problem with #1. If the Universe is incredibly fine-tuned in that were any of the common universal constants different, it would not exist or life would not exist, this would tell us nothing. If the Universe with Life exists, then these conditions were met. If the conditions were not met, the Universe would not exist and neither would the question or questioner. There is no conclusion that can be drawn from this argument, either way, fine-tuned or not. This is a time-waster thrown up by theists grasping at straws. So, we spend immense amounts of our time chasing such ephemera and when we prove the theory wrong or irrelevant, lo and behold another irrelevant theory gets proposed.
Steve,
The fine tuning question is related to a scientific question about multiverse. Implication for religion is very secondary and of no concern to scientists.
“Hidden due to low comment rating” Why?
here is the abstract:
http://arxiv.org/abs/0910.0023
http://www.sciencedirect.com/science/article/pii/S0370269311008471
http://journals.aps.org/prd/abstract/10.1103/PhysRevD.79.063521
http://cosmo.fiz.univ.szczecin.pl/pliki/mariusz/t3china1.pdf
http://www.cosmo.fiz.univ.szczecin.pl/pliki/mariusz/t1china4.pdf
http://cosmo.fiz.univ.szczecin.pl/pliki/mariusz/wawa2.pdf
“Hidden due to low comment rating” Why?
Maybe because people think that you have come to a wrong conclusion?
here is the abstract:
Evidence of publication is not evidence that you have not jumped to a wrong conclusion.
these questions will appear so dated by the end of the century .. cute, quaint, sincere .. and oh so off track
🙂
A question whose answer would not only encompass several of those asked by Carroll, but go beyond them, is implicit in the title of a 2012 paper by the UC Berkeley cosmologist, Eric Linder: “The Direction of Gravity.”
http://arxiv.org/abs/1201.5127
Linder discusses the curious conclusion that the well known turn-of-the-century supernova observations seem to indicate two opposing gravitational directions: Inward (local matter-produced attractions). And outward (cosmic repulsion; dark energy).
Not often explicitly acknowledged is the fact that this interpretation hinges on an assumption that permeates virtually all of Carroll’s questions; i.e., a fundamental discontinuity between matter and space. Especially obvious in the cosmological context is the assumed independence of space from matter. One expands (or contracts); the other does not. Matter is supposed to cause gravity to “suck” space out of existence; space itself is supposed to “blow” ever more of itself into existence. By this view gravity is rather schizoid.
Curiously, a 2011 paper with the same title as Linder’s
http://astroreview.com/issue/2012/article/the-direction-of-gravity
proposed an experiment by which these assumptions and interpretations can be tested. The latter paper is based on the observational fact that, if we were to base our assessment of gravity’s direction on accelerometer readings, we would conclude that it is outward. Gravitating matter produces only outwardly pointing accelerometer readings.
The poem by Wheeler, cited by Shriner, implies that a simple shift in perspective may be all we need to reveal what’s “behind it all.” An experiment that has the potential to bring about his shift was proposed by Galileo in 1632. It involves probing the inside of material bodies using a Small Low-Energy Non-Collider. As argued in
http://vixra.org/abs/1407.0041
we are overdue to perform Galileo’s experiment regardless of whether we expect a surprising result or not. When we finally get around to filling this gap in our empirical knowledge of gravity, the probe will either oscillate in a hole through a larger body of matter or it will not pass the center.
If it oscillates, then gravity is bi-polar and the space-matter discontinuity will be confirmed. Whereas if it does not pass the center then gravity has only one direction (outward) and space and matter would be seen as a continuum.
So the question is:
What is the direction of gravity?
Are we to continue believing our ancient visual impressions? Or should we believe accelerometers? Happily, we can replace belief with empirical facts. With a Small Low-Energy Non-Collider the question’s answer can be easily obtained. If the mono-polar, accelerometer-confirming result is forthcoming, then a drastically different set of cosmic questions would assert themselves.
Sean,
When is your next appearance on The Colbert Report going to be?
The “Unreasonable Effectiveness of Mathematics in the Natural Sciences- Wigner” is a sure hint for the creation of a mathematical model of REALITY. Is it possible to design nature “artificialy”? Lo and behold, I found some promising descriptions at http://www.qsa.netne.net/
If a mathematical model derive the laws nature, describe fundamental values as already found experimentally, then one can value such decriptive model as a reflection of truth.
I belief that reality can not be limited to a nature of 3D +1. A seamless mathematical description of reality of nD (inclusive of 3D) can be of immense value in answering some of the mysteries of nature. (I am looking forward to the future input from Lisa Randall.)
My input , as per invitation of Sean: Is nature exclusive? If it is, one must consider a mechanism choosing the model.
We have quanta with spin properties that do not spin, super symmetrical balls that appear and dissappear, string theory (3 versions), a Higgs bosun, neutrinos, interchangeable energy and mass, 95% dark matter and dark energy. Yet we seemingly have a consistent universe, and conservation of energy. Oh yes, let’s toss in four “magic-like” forces, to bind it all together. Hmmmm It doesn’t sound like we have it quite right yet, where we can afford to turn away possible simpler, yet plausible possible questions that haven’t been answered yet….
Could THIS SHAPE, be the sole ingredient in the universe? Permeating it. And creating a medium whereby gaps are the “matter” and it is the medium that “spins” around the gap.
http://imgur.com/plLoNrh
Creating a difficult to “see”, but simpler to believe universe. Totally mechanical, No magic. No friction, no heat, no momentum, just existence, and spin.
http://imgur.com/plLoNrh
Philisophically, I would suggest, simple + plausible trumps complex + magic.
Since the shape is a mathematical derivative of analysis of gravity waves from the CMB, the question seems all the more worth asking.
Could the universe be mechanical, and inverse?? if not, why not. that is MY personal question. 🙂
With all due respect, thank yyou for your consideration.
🙂
The difference between a “smart” person and a “dumb” person is not how much they know. The important difference in this dichotomy follows: A “dumb” person hates what they do not understand and a “smart” person loves what they do not understand. I can find no other difference.
I love this even if I don’t have the background to understand it all.
And I always forget the check box.
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I often ponder upon a wonder that manifests as a thought that evolution or change is the underlying ‘first principal’ or state needed to bring about existence per say and my thought in my mind mimics metaphorically the moment of singularity and the subsequent bringing about of the universe that enabled me to ponder upon this wonder in the first place, I just ignore the subsequent causality issue that arises as I have no wish to imagine I am “god”