SheBang (aka the BigOmega) ---- The largest set with whose elements that you can interact with. [''How do you define 'interact'? Usually it must be two-way. Do you intentionally exclude those systems that you can affect that cannot affect you, and those systems you cannot affect that can affect you?''] Since you can always interact with yourself, the smallest such set is the set containing only yourself. "You" in this case refers to any element, not just a sentience. Here I put forward that instantiation of a set is not an interaction because an interaction between elements of a set requires a timeline relative to the lifetime of the set. That is, actions (and hence interactions) occur in time. The time of a given set is an open interval. The instantiation lies on the point at the limit of the beginning of the time range, but not directly on it. In other words, the set has to be created strictly before anything in the set does an action. Thus, the act of creation cannot count as an action as that would mean that the act of creation was strictly before itself and that would be a contradiction. The implied axiom here is that time is linear, which is not necessarily true. -- SunirShah Time is not only nonlinear, time does not exist. It's an abstraction of our need to understand the Universe. We perceive order where none exists. When I was a child, I played with childish things... We are but children in a playroom full of building blocks. A single atom is a block and the Universe is the room. When we are mature, many, many millennia from now, we will step outside of the playroom, put down our blocks and transcend the Universe. - visasiv --- Ok, let's try again. Yes, time does not exist. Yes it is an abstraction. Time is the measurement of motion. It's a type of relationship. Just like distance. That doesn't exist either, it's a comparison between things. You might be able to say that 1mm is able to hold N (a really big number) Carbon atoms stacked up in a line. But 1mm does not exist as an entity in the universe, only the N Carbon atoms exist. Then to say that something is 3mm long means you can fit three of your N Carbon atom 'rulers' along the side of the thing being measured. The abstraction of time is used to compare the traversal of distances. It allows you to say: I was able to travel the distance of 300,000 of my N Carbon atom 'rulers' while at the same time, the earth rotated such that the Sun was directly overhead on two consecutive days. Oh, and as for the DefinitionOfUniverse, I think "Everything that exists" is clearer and satisfies OccamsRazor ---- I agree fully, in that time is just an abstract concept for not only measurement or observation of motion. In fact, time is more complex and expresses mostly a state of observed decay of whatever structure we may find in the universe. And, motion in itself is also decay, be it the observed space where something had been and now has/was moved to another place. In this case, the originally filled up room decayed into a room that is now filled with whatever tends to fill up free space, in this case for example the air surrounding us. Or, in case of a human being we observe time by comparing the outward appearance, outward since we cannot observe the decay inside the human body by natural means, by the looks of his or her skin, wrinkles and so on. Time, when being classified a measurement for states of complex decay, always requires an extrinsic mechanism to induce the change of state, or at least make it observable. In our environment we find aggressives like oxygen which is capable of inducing a wide variety of decay on metals, minerals and organisms. Next, we find ultra-high frequency rays emitted by the sun or other sources that will induce such change in the rate of decay, some of which that will cause imminent death, i.e. the rate of decay is at a speed that natural mechanisms of the organisms cannot compete with, i.e. by SelfReproduction of for example the cells that any organism is constructed of. And motion as in thermodynamics is also a form of decay of the equilibrium of forces that we would observe if it were not for the extrinsic forces. Energy, on the other hand, is always in a state of decay, as it always will be converted into another energy form or energy potential state, except perhaps for real static energies such as potential energy in objects where there are no other extrinsic forces and subsequently energy form conversion. To recap, time is observed decay, in my opinion. Motion of rigid and fluid or gaseous bodies is also observed decay of states of space in which those bodies move or are moved within themselves. This is due to the fact that we can only observe motion by comparing the state of the observed space at a "time" when it was filled up with a body of some sort with the currently observed state, which, in my definition, has entered a state of decay as it is no longer what is was before. -- CarstenKlein ---- However, the universe is just more complex than just observing decay. Or we could say that decay has two sides to it, on one hand you take something from somewhere and on the other hand you put something to somewhere else, just as in the existing definition of energy, which states that the total amount of energy in the universe is a constant, I think it is called PreservationOfEnergy, is it not? Perhaps we could then redefine decay as being an observation of change, as such, time would become the observation of change. -- CarstenKlein ---- Let us try to find a definition for the universe. The Universe 1. is the result of N-1 of previous evolutionary incarnations of what we (cannot) observe as the state of the universe back then (PAST). 2. is now in its Nth evolutionary incarnation and we can (cannot always) observe as the state of the universe back then and now, as we always can only observe the past and not the future nor present (PAST/PRESENT-PAST). 3. will have a N+1, ..., N+M incarnation of what we (cannot) observe as the state of the universe now and in the future (PRESENT/FUTURE). 4. , as everything that we can observe, must have created itself from a single zero-dimensional point in space-time, from that it grew to become first 1-dimensional, then 2-dimensional and now we find it to have 3-dimensions. Additionally we observe change, so we can also define that the currently observed universe is one of 4-dimensions, i.e. space-time. 5. , from the theoretical observation that the universe must have sprung into existence from a zero-dimensional point in space-time, where space-time is non-existent, stems the theory that there must be more dimensions than just the four we have defined under 4), namely meta-physicists propose at least nine, at most 11 to 12 dimensions that the universe beholds or is made up of. 6. is structured, from the smallest particles and anti-particles up to higher order structures such as the sun, or solar-system up to galaxies and clusters of galaxies. Included in that definition are also nebular fields of gaseous clouds or plasmas, black holes and the more hypothetical white-holes. Included also organic and anorganic life-forms that dwell on said higher-order structures and that themselves are higher-order structures, some of which have developed an intelligence so high that they might even show innate animation and not just animation due to external forces being applied on them, i.e. cells, organs, and from that plants, animals and humans. * ''This implies a one-dimensional, finite, discrete time. I'm not sure I'm willing to accept that as a 'definition' of a Universe, since by its definition we might not exist in a universe, and there may be other complex systems that most people would say constitute a 'universe' but that this does not accept.'' From that it seems that a definition of the universe is much more complex than just stating everything that is, as we find AntiParticles that cannot really be existent, if we state that Existence requires some form of either energetic or physical (bodily) state. And yet we observe or propose the existence of particles that do not have any estimated nor observed energy state but yet are required for inter-protonic or inter-neutronic forces to exist as they bind the three quarks that any of the Protons or Neutrons are made of. If we define EverythingThatExists as the DefinitionOfUniverse we come into trouble with the above particles. Besides physicists believe that there exist also VirtualParticles that have not yet been found but have been proposed, due to the common reasoning and understanding that for example Electrons have to be indivisible Particles in their own sense. And, besides that we also would have to find out about what every form of energy is, have to classify the existing types of space and what is more, have to find out about the N-1 previous incarnations of the universe. I'd like to find out, yet in NonExistence it is rather difficult to observe, as it is really a mess of totally unstructuredness, at least I myself can only observe it as the perfect chaos in its undimensionality containing all of the energy that we currently can observe, not to mention DarkEnergy that we currently cannot even observe but do think that it should exist. -------- Re: ''The largest set with whose elements that you can interact with.'' Because the universe is expanding, some of what we see in the distance is beyond our physical reach even if we could travel at the speed of light. It is moving away from us faster than the speed of light and the image we see of it is an old one. We can never interact with that stuff beyond the early light it sent out. If we shine a laser at it, it will never reach it. In the distant future the universe will appear almost black except for the local group of galaxies gravitationally bound together, probably the "Virgo group", and the dim "ghost" images of the last light of the wayward objects sent out before disappearing over the "expansion horizon", being stretched further and further down the spectrum until Gamma-rays become long radio waves. In fact, many of them have already disappeared over the expansion horizon. There is no way we can currently and futurely change a single molecule of the distant stuff. All we get are baby pictures. Maybe this is the AnthropicPrinciple keeping Darth Vaders from being able to kill off everybody with galactic nukes. -- top I was wondering about your statement that, [...] It is moving away from us faster than the speed of light and [...]. This would contradict general knowledge or should I rather say belief that it is not possible for assorted materia to travel beyond the speed of light due to limitations arising from infinite growth of mass and so on. As such, and if, the masses in the vicinity of or near the expansion point are moving beyond the speed of light, they would have to build up mass, i.e. they would have to densify in order to comply to the findings of Einstein et al. And, masses densifying to near infinite mass, would yield black holes, as such, everything beyond expansion point would be a black hole. And, thinking about our observable universe, it would consecutively mean that we are merely existing at some point in the event horizon of that single black hole surrounding us. This would, too, explain the unexplainable growth of expansion rate of the observed universe. Am I correct with that assumption? -- CarstenKlein ''Well, that is where relativity comes into play. From our perspective it is simply slowing down its activity, in suspended animation. From our perspective it is *approaching* the speed of light, but also it's "metabolism" is slowing down because it is approaching that limit. It is the same thing, just a different perspective. And, the acceleration event horizon is for all practical purposes a black hole to us because light cannot "escape". From our perspective, no physical light limit has been exceeded. -- top'' It is possible, even under relativity, for the distance between an observer and a signal source to separate at faster than the speed of light even if neither the observer nor the signal is moving at the speed of light. This requires only that space itself is expanding at a sufficient rate between observer and signal source. ---- I wonder about the nature of a black hole... and whether it is possible that we're within one in some 'exterior' universe. It certainly might explain all that dark-matter our physicists predict. However, you'd think that there would still be some sort of 'white hole' from which all material is still exploding in a continuous fashion. OTOH, given that time as measured in the external universe would be compressed (from our perspective) down to almost nothing, our entire existence could come and go in the time it takes for one more 'exterior' universe atom to enter 'our' universe. In any case, I'd tend to Define 'Universe' in such a manner as to allow fictional, thought-experiment, and simulation universes to qualify. 'Our' universe, then, would be the one in which we participate directly. ''Time in a hypothetical 'external' universe would '''not''' be compressed according to an observer inside the event horizon. Temporal compression effects come from acceleration, and light falling into the black hole would not be accelerated during its journey. See the comments at the end of BlackHolesHaveNoHair. (And I don't see a connection between being inside a black hole and dark matter, other than the words "black" and "dark".) -- AnonymousDonor'' The event horizon of a black hole is not the black hole... it's just the part where light no longer escapes. The event horizon has volume. IIRC, the hole itself, the 'singularity', has none, at least from any external viewpoint. If there is no space, and time is a measure of motion within a space, then there is also no time within the black hole... not from an external viewpoint, at least. Everything's frozen. OTOH, physics within a singularity are largely unknown. Wrgt. dark matter, I'm curious what gravitational effects would be felt within a singularity by the space exterior to it or paired black holes in fixed orbit. You can probably tell I'm no expert in this field.... I'll check the comments. ''Talking about a singularity's "inside" makes no sense; a singularity is a zero-dimensional (point) discontinuity. Speculating about conditions within a singularity is like wondering how much the non-existent grufflelumph weighs.'' ''As for white holes, the only discussion I've seen of such a possibility concluded that a wormhole between a singularity and white hole would pinch off immediately.'' Sure it makes sense. A singularity is only necessarily zero-dimensional to those of us observing it from the outside. Yes, that does leave us free to speculate like blind philosophers... but unlike speculating about the non-existent 'grufflelumph', we actually ''know'' that singularities exist. We can't get information out of them, unfortunately... but it is still possible to determine which models fit our observations of them without contradiction. Further, various theories indicate that space and time expand from a singularity (e.g. the 'big bang' theories). If we accept such a theory as hypothetical, we can observe our own universe for an understanding about the properties within what we view as a singularity that initially has zero space and zero time. Indeed, I'm apparently not the first to speculate this (not unexpected; I'm glancing over the shoulders of giants and all that...). From the Wikipedia entry on White Holes: ''A more current view of white holes takes into consideration a revision to the standard model of the big bang theory which states that the big bang is an explosion that happens within a black hole, with the expansion that follows the traditional interpretation of the big bang, expanding into infinite space inside the black hole. In other words, a miniature universe is created at the core of the black hole, which expands into extra dimensions outside of this universe. The expansion taking place in this new miniature universe, if it could be perceived from an observer from this universe, could be looked at as a white hole. Matter that could not escape the intense gravitational pull of the black hole in this universe is instead sent speeding into the newly expanding baby universe.'' It goes on to add its own speculation regarding Dark Matter and Dark Energy. ---- CategoryDefinition