Anton, thanks for your long comment. I will try to respond to some of your points

"nothing indicates that a black hole actually does have an event horizon"

See for example http://arxiv.org/abs/astro-ph/0310692 which claims otherwise. Of course you can always dispute this if you are skeptical. I am only saying that I find the evidence "highly convincing", not that there is no room at all for doubt.

"If nothing can escape from behind the horizon, no photons nor gravitons, then you'd say that the mass inside the horizon cannot be expressed as gravity outside of it"

This is acommon misconception see e.g. http://physics.stackexchange.com/questions/937/how-does-gravity-escape-a-black-hole

"Another point is that though energy is quantified, that does not mean that there is a universal minimum building block of energy or space."

I have not claimed that there is a minimum energy, no such argument exists. The Planck energy for exmaple is much larger than the energies normally found in particle physics.

However there are reasonable arguments to expect a minimum distance scale at the Planck length. One argument is that to probe smaller distances the amount of concentrated energy needed would form a black-hole. Of course this argument requires many assumptions and could easily be wrong. I did not rely on such an argument in my essay. Information content is limited by the holographic principle. Of course if you are skeptical about black-holes I cant expect you to except such arguments and I leave you to follow your own path.

best regards, Phil

The question of dimensions is a very good one and I do not have all the answers. A long time ago I proposed the idea that dimensions were built by a process of multiple quantisations that add one dimension each time. I have no idea if this is the right way to look at it but the structure of necklace algebras suggests it.

A necklace algebra is a one dimensions object formed as a lie algebra of vector spaces strung along loops. But a lie algebra is itself a vector space so necklaces themselves can be strung along loops and this builds two dimensional structures. You repeat this adding one dimension each time. I found a nice construction on this idea where commutation relations on the string were used making it look like a process of quantisation, hence the idea.

The problem with that is that it builds discrete multi-dimensional structures and you have to explain why spacetime, strings, branes or any other multidimensiaonla structure appears continuous. The mapping I describe in this essay which uses iterated integration is a step towards understanding that. There are other ways you can look at these things and no complete theory.

I also like the ideas on dimensions in your essay. This is an important part of the overall puzzle

Hi Phil,

Thanks for the links. As one can fall into a black hole, I can imagine the mass or gravitational field within the horizon to continue outside of it. However, if when nothing can escape from behind the horizon so an observer outside of it cannot interact with what's inside of it, then the area the horizon encloses still would be a space where all points are physically identical to him, which I think is impossible.

The paper you refer to doesn't prove that a black hole has an event horizon, it only proves that it has no surface, unlike a neutron star. In a self-creating universe (as opposed to a big bang universe) a black hole has no surface nor event horizon.

Though I'm familiar with special relativity (SR), my math is rusty, not up to comprehend general relativity (GR) so I try to understand it using what I know of SR -if such a thing is possible. My problem with GR is that while according to Einstein ''the inert mass . . . increases when ponderable masses approach the test body.'' (''The Meaning of Relativity'' p 97) agrees with the notion that particles and particle properties must be both cause and effect of their interactions. However, that there exist solutions of Einstein's field equation ''that ascribe inertial properties to a single particle in an otherwise empty universe'' (''Concepts of Mass in Physics and Philosophy'' (2000) Max Jammer p 157) contradict it since to have properties requires the existence of something to interact with, to express it. Ignoring this, a particle can only have mass in an empty universe if it only is the cause of forces, if its mass is an inherent, privately owned quantity. So my question is whether the energy in some area which goes into Einstein's field equation is, as I suspect, an absolute quantity, only the cause of forces, in which case a black hole indeed would have an event horizon.

A related point is that when we must reject causality (as you do in your 2012 essay), then we can no longer interpret the 'speed of light' as a (finite) velocity of light, but as a property of spacetime, which is something else entirely (see http://fqxi.org/community/forum/topic/1328), even though it obviously is a limit to the velocity massive objects can move at. So my next question to you is whether a black hole has an event horizon or not depends on whether the 'speed of light' refers to the velocity of light or to a property of spacetime?

From the arxiv paper you referred to:

''A black hole represents the ultimate victory of gravity, where all the mass in the object collapses down to a ''singularity'', a true geometrical point. The object has no material surface. Instead, surrounding the singularity is an ''event horizon'', which plays the role of a virtual surface. The event horizon is a one-way membrane through which matter and energy can fall in from the outside, but nothing, not even light, can escape from within. The region inside the horizon is thus causally cut off from the outside world. In a real sense, the horizon serves as an effective surface, even though there is no actual material there.''

What I object to in this quote is ''the ultimate victory of gravity'' which implies the mass to be the cause of the collapse: if and when the mass of objects indeed is both cause and effect of their interactions, then all objects within the interaction horizon of the star which is to become a black hole is involved in its collapse, which would imply that no information is lost as it does?

As my knowledge of GR is so poor, I'd be very grateful if you would take the trouble to answer my questions,

Regards, Anton

    You asked "So my next question to you is whether a black hole has an event horizon or not depends on whether the 'speed of light' refers to the velocity of light or to a property of spacetime?"

    You should not think of the "speed of light" as just the speed of light. It is the maximum speed that any particle can travel at. The s"peed of light" is determined by the light cones which are the null directions of the spacetime metric. The metric is the gravitational field, so really the "speed of light" is a property of the gravitational field. This is why it is directly related to the black-hole event-horizon.

    you asked "...which would imply that no information is lost as it does?" I am confused about what you are asking but will say what I think.

    In the paper they talk in causal terms about the formation of the black-hole. I dont think causality is fundamental so the statement has its limitation, but the emergence of causality is sufficiently clear to make sense of the statement.

    Looking at the bigger picture I would say that causality for a black hole should be considered more carefully. The time reversal of a black-hole is a white hole yet a static black-hole is identical to a static white-hole. If you could see the Hawking radiation emerging from a black-hole where would it appear to originate from? You can't tell because it is thermal so it does not form any kind of image that let's you see where it is formed. It looks the same as thermal radiation originating from inside the event-horizon of a whitehole, so what is really happening and how should we view causality around a black hole? These questions cannot be answered with classical general relativity and we dont have a full quantum theory so the amnwers are not known to anybody.

    Phil,

    Let's philosophize about your ideas.

    In all this talk about information and black holes, the information has a carrier. However, if you say that information is fundamental and spacetime and matter are emergent, there is no such carrier. Historically, a similar starting point (note that I'm not saying "identical") can be found in Berkelian idealism, which revolves around the principle "esse est percipi". The object then doesn't exist if you don't observe it (and thus have no information about it).

    Now surely you don't want to revisit this Berkelian idealism, so I assume that in your theory information is something that exists in itself, outside an observer, and doesn't have to be "consumed" or "absorbed" by us for a matter particle to emerge, that is, to come into existence. But still, this leaves open the question of how the process of emergence can be detected. In other words: if you want an information based theory to be classified as "physics" - as opposed to a mere metaphysical idea - how can you in principle prove experimentally that information precedes matter?

    Best regards,

    Marcoen

      Dear Philip,

      I rate your essay as a most appreciated one for some reasons:

      It supports Wheeler's "it from bit" credo and nurtures hope for getting rid of notorious enigmas including Einstein's worry about the now.

      It certainly does not matter that I tend to share Shannon's opposite view. All contest winners so far tried about the same as do you.

      It will perhaps also not matter much that your reasoning relies at least in part on speculations and denies that "symmetry is just a kind of redundancy". I may be the only lonely one who considers T-symmetry an apparent and redundant one which can be attributed to Heavisides trick of analytic continuation with arbitrarily chosen reference. I would appreciate you proving me wrong in that respect.

      Regards,

      Eckard

        Marcoen, it is a good question and I will try to give an answer from my own point of view. General statements about emergence are pf course metaphysical so they cant be decided by experiment, that is the definition of metaphysical. metaphysical ideas are just heuristics we use to develop more physical theory which should ultimately lead to testable predictions. However that is a long road and as far as quantum gravity is concerned the journey has just begun.

        I see thr most fundamental structures such as information are logical possibilitities. Some people may say that exist in some Plantonic realm but that is pure philosophy and and try to avoid that (not always successfully) I dont think we need to talk about whether that information is carried by something or where is comes from. Other people can talk about that if it helps, but I see it as unnecessary baggage.

        What counts is how such logical structures can be used to build a framework for theories. To find this we start from existing theories and use thought experiments based on arguments of logical consistency being careful to note our assumptions. I think that holography leads us to think in terms of information as fundamental, if the assumptions are right. I also think that the meeting of quantum mechanics and gravity for weak fields implies string theory, and string theory has the structure of qubits built in. Other approaches lead to similar conclusions, so I thin we should try starting with qubits as the most fundamental objects.

        From there we need to develop the theory. This is work that is still in its infancy. If it succeeds it will lead to a complete theory which can then be used to make predictions, but it is no use asking for that to happen soon. If that works out it will be some justification for the idea that information is fundamental because it led to a correct theory, but there may be a different way of getting there from some other metaphysical principle, in which case you can never prove that one idea is better than another.

        Eckard, thanks for your comment.

        Remember that the only part of "symmetry is just a kind of redundancy" that I deny is the word "just"

        I am not sure exactly what you mean about Heaviside's trick. One thing to remember is that a Laplace transform is asymmetric in time. It favours decays rather than growth. You can still turn it round in time and apply but it may diverge. When you are looking for sources of time asymmetry from time-symmetric equations you have to be careful to see where you may build in the asymmetric assumption.

        Hi Philip

        A Big Bang Universe (BBU) lives in a time realm not of its own making: it has a beginning and evolves as a whole IN time: as in this universe it is the same cosmic time everywhere, it takes a photon time to travel, so we can imagine to follow a photon on its path like we can, from the Skylab, follow a plane as it flies from New York to Boston, so this universe grows older as the photon travels: in this universe the speed of light does refer to the motion, to the velocity of light. In contrast to a BBU, a Self-Creating Universe (SCU) obeys the conservation law which says that what comes out of nothing must add to nothing, so here everything inside of it, including space and time somehow has to cancel. The consequence of this is that this universe has no physical reality as a whole, a 'seen' from without, so to say, but only exist as seen from within. This is not unlike the fact that the sum of all debts and credits on Earth by definition is zero doesn't mean that there exists no money: it only exists, has reality to the inside debtors and creditors. Since money is only defined on Earth, that is, since the meter, second, joule and gram aren't defined outside the universe, we cannot ask how old or large it is, how much energy it contains nor what its entropy is, just like to an alien who cannot trade with us, the value and quantity of money on Earth is undefined.

        As a SCU therefore does not live in a time continuum not of its own making but contains and produces all time within, which only is possible if clocks must be observed to run slower as they are more distant, even when at rest with respect to the observer (though it remains to be seen whether they can, indeed, be at rest). As a result, and unlike a BBU, in a SCU it is not the same time everywhere: as here a space distance is a time distance, a photon bridges any spacetime distance in no time at all, meaning that we don't see a distant galaxy as it was in a distant past, in THE past, but as it is at present, to us. In a SCU concepts like cosmic time and THE past have no meaning whatsoever.

        The consequence of non-causality is that we can no longer ask which particles are the cause of a photon transmission, the particles involved in its emission or those involved in its absorption as this would require that we can determine in an absolute sense what precedes what, which is impossible in a BBU for practical reasons (you'd need to step outside the universe), and in a SCU for principled reasons. If A emits a photon which is absorbed by B, a transmission which changes the state of both atoms (and hence affects all particles within their interaction horizons), then A sees B change at the time it emits the photon, as soon as A changes itself so sees a slightly changed world, whereas B sees A change at the time it absorbs the photon, as B changes itself and hence the world it observes. That is, unless we believe that B, after absorbing the photon sends back a thank-you-note confirming the receipt of the photon, informing A that it can, as of this moment, the receipt of the note, start to see B in its new state. In a SCU both A and B are equally right about the time of the emission, so here the transmission must be instantaneous, which according to relativity theory, from the pointy of the photon, it is indeed.

        Let's suppose an observer A near and some distance above a laser, its beam directed away from him towards a distant point B, in a somewhat dusty space, turns on the laser. In a SCU he observes events to happen at a slightly slower pace at larger distances, so he can, in principle (or when using a high-speed film camera) see the progress of the beam in time by the light reflected back towards him by the dust particles. Though it therefore looks as if light moves, from the laser to B, this is an optical illusion: the fact that he sees clocks run slower as they are more distant doesn't mean that they actually do run slower, that light is something which moves at a finite velocity, from cause to effect. In contrast, in a BBU clocks at rest run at the same pace everywhere, and would, when set at zero at the bang, show cosmic time if we ignore the relativistic effects of gravitational fields, so here these observations must be interpreted as proof that light moves at a finite velocity.

        That we cannot experimentally determine whether c must be conceived of as a (finite) velocity or as a property of spacetime, combined with the fact that an instantaneous transmission over any spacetime distance would make the riddles of quantum mechanics like entanglement, the EPR paradox and the double-slit experiment self-evident, should at least give pause for thought.

        I think that an emergent causality is a contradiction in terms, so your statement that causality emerges in an acausal universe seems to me a capitulation to causality. I'm afraid that big bang cosmology makes no sense at all, that the observational 'evidence' for the big bang rests upon a systematic conceptual misinterpretation of observations.

        Regards, Anton (and I will pester you no more)

          Phil,

          Thanks for your answer, you summed it up real nice.

          Although I myself do not believe in quantum mechanics - that is, I'm compelled to believe that it has merit but I do not believe it is the final answer - I can understand that this information thing is thought of as a viable route to a complete theory.

          I think your essay is spot on for this contest. In my rating I deducted a point, however, for mentioning that egocentric windbag 't Hooft in the text.

          Best regards,

          Marcoen

          Thank you for your comments. I will just add one remark.

          It is temporal causality that I consider to be emergent. I accept the deeper ontological causality or reductionism that some people prefer to question. Emergence happens through ontological causality so there is no contradiction in saying that temporal causality is emergent.

          Hey Phil,

          There seems to be some sort of weird synchronicity phenomenon at play here - or maybe the NSA is playing games with me . . . Anyway, I was "directed" to this interesting paper by Kevin Knuth and Philip Goyal titled, "Quantum Theory and Probability Theory: Their Relationship and Origin in Symmetry" in which . . . well, here's the abstract:

          "Quantum theory is a probabilistic calculus that enables the calculation of the probabilities of the possible outcomes of a measurement performed on a physical system. But what is the relationship between this probabilistic calculus and probability theory itself? Is quantum theory compatible with probability theory? If so, does it extend or generalize probability theory? In this paper, we answer these questions, and precisely determine the relationship between quantum theory and probability theory, by explicitly deriving both theories from first principles. In both cases, the derivation depends upon identifying and harnessing the appropriate symmetries that are operative in each domain. We prove, for example, that quantum theory is compatible with probability theory by explicitly deriving quantum theory on the assumption that probability theory is generally valid."

          Taken in the context of the infinite-order probability stuff it seems to bring everything full circle - or maybe it's an infinite spiral, or better yet, an Oroborous! Perhaps you would find the ideas and, more importantly, the proofs useful for your own theoretical work . . .

          With regards,

          Wes Hansen

            I will try to explain it again.

            Causality is about answering the "why" questions. We answer with an explanation that begins with the word "because". In other words we explain a "cause".

            However causality can take different forms and different philosophers have classified different types of cause in different ways. In the past Einstein used the word "causality" when talking about quantum mechanics to refer to what we now call "determinism". All this creates a lot of confusion.

            Some scientists say that science is not about answering why questions. It just says how things happen, not why. Others say that causality is so fundamental to science that it is meaningless to say that causality is not fundamental.

            One type of causality that people are particularly attached to is temporal causality. This is the idea that cause precedes effect. Everything that happens is caused by something that happened earlier. This refers to real-world physical events that have a place and time. Temporal causality cannot tell us about general facts of existence like why the electron is charged because this is not something that happens at a particular place and time. Answering those types of questions requires a different type of causality that we call "ontological causality" Ontological causes do not proceed ontological effects in time, they just explain why things are the way they are. For example I could day that momentum is conserved because of transaltional symmetry and Noether's theorem.

            A conservative view would be that temporal causality is fundamental but ontological causality is just reductionism and is not what science is about. I take the opposite view.

            Temproal causality is not fundamental. People might have been excused for thinking so in the 19th century but now we know that the fundamental laws of physics are time symmetric so they can not distinguish cause from effect. The arrow of time emerges as a macroscopic effect from thermodynamics which tells us that entropy always increases in one time direction. The direction depends on boundary conditions so it is a feature of the solution of fundamental laws, not the laws themselves. We can try to reduce the principle of temporal causality to the statement that operators commute if they are not inside each other light-cone. But even the geometry of lightcones is a dynamic feature of gravity, not a fundamental feature of physics. It depends on the spacetime metric which is the gravitational field. The causal structure of spacetime is part of the solution of the equations of gravity, not something that is built-in.

            This is why we say that temporal causality is emergent. This enmergence is not something that happens in time. You cant say that at some time in the past there was no temporal causality and then something happened and it emerged. That would be a contradiction in terms as you pointed out. Emergence of temporal causality is ontological, not temporal. We have to explain why temporal causality is part of our everyday experience when it is not part of the fundamental laws. When we do that we use ontological causality, not temporal causality so there is no contradiction.

            Dr. Philip,

            Thanks for your query. Before the first mind? Of course there were Its and Bits, but to make meaning out of them the existence of mind or something similar to that is essential. I have stated in my conclusion that, 'It and Bit in themselves are empty and blind without mind'.

            If you are asking regarding the existence of first mind, you will find answer to that in detail in the 'biology' section of my essay. There I have explained clearly how mind came in to existence (as a result of the evolution of Life for over billions of years). If you have further queries, please, inform me.

            I have gone through your essay once and want to see it once more, before I post my comments on it.

            Regards,

            sreenath