Spyman

If you claim that people need to wear hats made of tin-foil because aliens are visiting Earth and controlling or reading our minds then you are likely to get labeled as such but not if you belive in the possibility that Jupiter's moon Europa could have an subsurface ocean with potential for extraterrestrial life under its ice crust. Frank Drake for instance is a well acknowledged scientist and Emeritus Professor of Astronomy and Astrophysics, most famous for founding SETI and the Drake equation to estimate the number of detectable alien civilizations in our galaxy.

Sorry for the off topic, but IMHO you should start a blog for your musings.

Youngsters are exposed a lot out in the world, but that is not a reason for us to give in. We should instead try to lead with good example, both with knowledge and attitude. You might find it funny and don't care but I and hopefully other members do. While "puck" isn't a swear word "screwed" definitely is, showing that it is easy to misuse these words without noticing, which also obviously means there are enough profanity for a filter to improve the language here. AFAIK with a profanity filter a lot of video games are allowed for 12 years olds and while a 12 year old probably don't come here to read the relativity subforum, we still have lots of other subforums where kids of any age can ask any questions they want, we even have a subforum for homework. I for one is very convinced that kids do come here to read and learn science. If you are bored and tired then go get some good sleep and come back later well rested.

Obviously I don't think ydoaPs question is something to joke about... Do we want young kids to come here to read and learn science? Do we want young kids to come here and read offensive language?

Current electronics have limits that prevents improvement to continue exponentially, but we don't yet know the limits of new technology. We could be close to a major breakthrough in either optical or quantum computers which would likely push the potential capacity very far into the future.

Check out recent threads by hal_2011. [EDIT] Ooh, you are already participating there, then why are you asking if you know?

No, if a 10 solar mass star would turn into a Black Hole then its gravity at the Event Horizon would be from 10 solar mass. No, the core of the Black Hole is deeper in the gravity well than the infalling observer and is subjected to even more time dilation and will persist longer.

No, Airbrush quoted a maximum spin for the Event Horizon and not the Singularity. Kerr metric determines the circumference of a spinning Black Holes Event Horizon and mass is the only variable. According to Kerr's metric the Event Horizon would vanish leaving the singularity naked. Frame dragging are limiting objects from entering rotating Black Holes due to angular momentum. Relativistic jets are thought to be extracting energy from spinning Black Holes.

Now I am even more confused about what you are asking...

Nope, if the initial explosion was symmetric then the whole shell in total must remain symmetric even if individual objects inside it coalesces into more massive clumps. Small sidenotes: Where is the difference between gravity and light in your argument? Obviously there are no gaps in the sunlight shining on Earth either, it is also steady even though it takes time for it to reach us. Why would it take eight minutes before Earth takes off from orbit after the Sun disappears if gravity acts instantly? If there is no time delay then the Suns gravity should vanish instantly with the Sun.

Huh, didn't you read my post? If you don't want to discuss then why opening a thread on the subject?

If pi would represent space in an analogy then we are from our point of view on the first digit (3) and looking outward we can currently only see ~46 billion digits in a circular sphere around us. That makes the world symmetric around us and doesn't tell whether there really is an asymetry or if there is any edge at all further out. If pi represents time then we are not able to view any further into the future and determine if there is any end of time. According to cosmological time keeping we are on the ~14 billionth digit since when looking back in time we can not see further than what we perceive to be the first digit (3), but we don't know what or if there was a before. I don't think I understand your question, clearly pi exists, has an edge and an infinite row of digits but there is no reason that the world must be like pi. The Universe could be finite without any edges or infinite in extent and if the world somehow turns out to be like pi then we would have to accept that the world is totally asymetric.

If you are abandoning the symmetrical shell that normally would be the remnant of an explosion in vacuum then I think your model need to explain how that is possible and how the remnant is shaped. For a supernova explosion the outer shell is closely spherical and gravitationally symmetric, which therefore means it is not able to by gravity affect anything inside it. More dense areas inside our membrane could be able to pull us sideways and if the outer shell is "incoming" such that it already have collided with our shell and have certain parts already inside our membrane, then those could also interact gravitationally and pull us sideways. But as already proved: explosions are gravitationally symmetrical and outer shells are not able to pull us outward. Thus your model is not able to explain the observed acceleration of expansion. You need to accknowledge this before we can continue and look at other problems with your model. Gravity is predicted by Relativity to propegate with lightspeed but AFAIK not yet directly confirmed by measurements. (Altought there is indirect observational evidence for gravitational waves.) IMHO derailing the thread into Relativity or arguments concerning the speed of gravity will likely ruin the discussion of your model.

Yes, sorry, maybe I should have mentioned that, I never meant to argue, only thought you would find Dark Flow interesting in the context.

I used the example of pi in the other thread, it has a starting point, (the digit 3), and then continues to have infinite decimals. So it has an edge and is still infinite in length. We don't know if the Big Bang is the edge of spacetime, it is currently our theoretically edge of observation but not necessarily a true edge.

You might find it interesting to know that there might have been something huge and very dense inside our past light cone in early times, while it is now outside so we are unable to observe it, we are still able to observe its effects on our surroundings. The discovery of a Dark Flow is still highly controversial and could likely turn out to be false but can also end up getting confirmed. My understanding is that before the Recombination the Universe was to "foggy" to let light traverse, but since gravity is not limited by such restrictions our part of the Universe could have been affected by a surrounding neighborhood that moved beyond our cosmic horizon before the Recombination. As such we are not able to view this neighborhood but we can observe the imprint its gravity left behind. Mysterious New 'Dark Flow' Discovered in Space As if the mysteries of dark matter and dark energy weren't vexing enough, another baffling cosmic puzzle has been discovered. Patches of matter in the universe seem to be moving at very high speeds and in a uniform direction that can't be explained by any of the known gravitational forces in the observable universe. Astronomers are calling the phenomenon "dark flow." The stuff that's pulling this matter must be outside the observable universe, researchers conclude. http://www.space.com/5878-mysterious-dark-flow-discovered-space.html Dark flow is a term from astrophysics describing a peculiar velocity of galaxy clusters. The actual measured velocity is the sum of the velocity predicted by Hubble's Law plus a small and unexplained (or dark) velocity flowing in a common direction. According to standard cosmological models, the motion of galaxy clusters with respect to the cosmic microwave background should be randomly distributed in all directions. However, analyzing the three-year WMAP data using the kinematic Sunyaev-Zel'dovich effect, the authors of the study found evidence of a "surprisingly coherent" 600–1000 km/s flow of clusters toward a 20-degree patch of sky between the constellations of Centaurus and Vela. The authors (Alexander Kashlinsky, F. Atrio-Barandela, D. Kocevski, and H. Ebeling) suggest that the motion may be a remnant of the influence of no-longer-visible regions of the universe prior to inflation. Telescopes cannot see events earlier than about 380,000 years after the big bang, when the universe became transparent (the Cosmic Microwave Background); this corresponds to the particle horizon at a distance of about 46 billion (4.6×1010) light years. Since the matter causing the net motion in this proposal is outside this range, it would in a certain sense be outside our visible universe; however, it would still be in our past light cone. http://en.wikipedia.org/wiki/Dark_flow

Yes, thats is correct. Individual objects in a surrounding shell does of course interact gravitationally with objects on the inside. What Newton proved is that if the shell is symmetric then when considering the whole shell, the sum of forces from all objects it consists of cancel out for inside objects. When the inside object moves closer towards the shell, it will also get less of the shell ahead and more of the shell behind it.

If nothing is infinite then how many digits are there in π? "π is an irrational number, which means that its value cannot be expressed exactly as a fraction m/n, where m and n are integers. Consequently, its decimal representation never ends or repeats." http://en.wikipedia.org/wiki/Pi How do you imagine the Universe, if space has some cind of borders then what would be there on the others side? Currently we don't know if space is curved and finite or infinite and without end, we are not able to observe beyond our visible horizon but there is no known reason why the Universe can't be bigger or even infinite in size. "The universe is immensely large and possibly infinite in volume. The region visible from Earth (the observable universe) is a sphere with a radius of about 46 billion light years, based on where the expansion of space has taken the most distant objects observed. For comparison, the diameter of a typical galaxy is only 30,000 light-years, and the typical distance between two neighboring galaxies is only 3 million light-years. As an example, our Milky Way Galaxy is roughly 100,000 light years in diameter, and our nearest sister galaxy, the Andromeda Galaxy, is located roughly 2.5 million light years away. There are probably more than 100 billion (1011) galaxies in the observable universe. Typical galaxies range from dwarfs with as few as ten million (107) stars up to giants with one trillion (1012) stars, all orbiting the galaxy's center of mass. Thus, a very rough estimate from these numbers would suggest there are around one sextillion (1021) stars in the observable universe; though a 2010 study by astronomers resulted in a figure of 300 sextillion (3×1023)." http://en.wikipedia.org/wiki/Universe

For the person falling into the Black Hole spacetime would be very curved relative the distant observer, so in his view the Event Horizon is even more further down and while he continues to move closer, he will never be able to reach it. Interacting with an event horizon An observer crossing a black hole event horizon can calculate the moment they've crossed it, but will not actually see or feel anything special happen at that moment. In terms of visual appearance, observers who fall into the hole perceive the black region constituting the horizon as lying at some apparent distance below them, and never experience crossing this visual horizon. http://en.wikipedia.org/wiki/Event_horizon#Interacting_with_an_event_horizon

It is called "Dark" because we don't yet know what it is but are able to observe its effects. Current observations indicates that it will never slow down. There is currently no known force able to bring the expansion to halt. Dark energy In physical cosmology, astronomy and celestial mechanics, dark energy is a hypothetical form of energy that permeates all of space and tends to increase the rate of expansion of the universe. Dark energy is the most accepted theory to explain recent observations and experiments that the universe appears to be expanding at an accelerating rate. In the standard model of cosmology, dark energy currently accounts for 73% of the total mass-energy of the universe. http://en.wikipedia.org/wiki/Dark_energy Future of an expanding universe Observations suggest that the expansion of the universe will continue forever. If so, the universe will cool as it expands, eventually becoming too cold to sustain life. For this reason, this future scenario is popularly called the Big Freeze. The future of an expanding universe is bleak. If a cosmological constant accelerates the expansion of the universe, the space between clusters of galaxies will grow at an increasing rate. Redshift will have stretched ancient, incoming photons (even gamma rays) to undetectably long wavelengths and low energies. Stars are expected to form normally for 1×1012 to 1×1014 years, but eventually the supply of gas needed for star formation will be exhausted. Once the last star has exhausted its fuel, stars will cease to shine. According to theories that predict proton decay, the stellar remnants left behind would disappear, leaving behind only black holes which themselves eventually disappear as they emit Hawking radiation. Ultimately, if the universe reaches a state in which the temperature approaches a uniform value, no further work will be possible, resulting in a final heat death of the universe. http://en.wikipedia.org/wiki/Future_of_an_expanding_universe The Great Cosmic Battle The expansion of the Universe itself provides an intensely dramatic example of the ubiquitous struggle between the force of gravity and entropy. As the Universe expands and becomes more spread out, gravity resists this trend and tries to pull the expanding Universe back together. The particular fate which our future holds depends on whether gravity wins or loses this cosmic battle, whose outcome depends on the total amount of mass and energy contained within the Universe. Current astronomical data strongly suggest that gravity has already lost this critical conflict and our fate will be determined by a continued and unending expansion. http://www.astrosociety.org/pubs/mercury/0001/cosmic.html

First off - my name here is "Spyman" and "Prowler" is only my user title, while I think I am alone using it, there are lots of other titles like the "Meson" you have that is used by several persons, so to avoid misunderstandings I think it's best to stick to peoples choosen names. Secondly, it was not me saying that, I clearly quoted Wikipedia and gave a link to the source of the quote. You are expressing it as I am the one making that claim as if you want to downplay its credibility but the shell theorem in my quote is well proven beyond doubt in classical mechanics. Lastly, my reply to your two presented arguments regarding multiple shells and a simplified view in one direction: It doesn't matter how many shells there are, you can still make an arbitrary choice between any two adjacent shells and from that layer declare all inner shells as one "center point" and all other shells as one "hollow ball". According to Newton's law of gravity the "center point" would be gravitationally pulling in on the surrounding walls of the "hollow ball" but the walls themselves is unable to affect any bodies on their inside. When the shells are gravitationally symmetric, in roughly spherical shapes and with distinct borders where the inside boundary of larger shells completely encapsules all smaller shells, there is no net gravitational force exerted from any of the outer shells on any of the inner shells. Adding more smaller shells on the inside doesn't change anything else than increasing mass at the center point. Adding more larger shells on the outside doesn't change anything at all, since they will all be unable to affect anything on their own inside. The shell theorem shows that a simplified view in one direction does not work in a full three dimensional reality. If you want to model a world with three spatial dimensions then you need to fully account for all of them.

why? =D someone must have for you to tell me i cant If everyone would make up their own definition of random words as they pleased, then we would all end up speaking very different individual languages, making it impossible to understand each other.

No it still won't work because even though individual parts might seem randomly dispersed, momentum is still conserved for the whole explosion making it symmetric in each dimension. "Momentum has the special property that, in a closed system, it is always conserved, even in collisions and separations caused by explosive forces." http://en.wikipedia.org/wiki/Momentum#Conservation_of_linear_momentum

http://en.wikipedia.org/wiki/Acceleration#Uniform_acceleration

According to Newton's law of universal gravitation your hypothesis of an outer shell pulling us outward via gravity is impossible, the net gravitational forces acting on any body, at any location on the inside, from the bodies surrounding it in an outer shell cancel out. "In classical mechanics, the shell theorem gives gravitational simplifications that can be applied to objects inside or outside a spherically symmetrical body. This theorem has particular application to astronomy. Isaac Newton proved the shell theorem saying that: A spherically symmetric body affects external objects gravitationally as though all of its mass were concentrated at a point at its centre. If the body is a spherically symmetric shell (i.e. a hollow ball), no gravitational force is exerted by the shell on any object inside, regardless of the object's location within the shell. Inside a solid sphere of constant density the gravitational force varies linearly with distance from the centre, becoming zero at the centre of mass. These results were important to Newton's analysis of planetary motion; they are not immediately obvious, but they can be proven with calculus." http://en.wikipedia.org/wiki/Shell_theorem