Spyman

I wanted to know in what shape this uneven rates of expansion would form, like if the spherical shell flattens out to a disk, gets uniform like an egg, grows corner like an box or streaches out in a bar shape. What shape does you think the spherical shell would transform into? As I understod your model you have one center from where everything orginates, which then means that everything "out of sight" also has orginated from there sometime in the past or at least share the same center of mass. If you dislocate the center of mass then your Bang is no longer in the center of the Universe, which would mean that everything from the Bang would accelerate asymmetric towards the center of mass. If you introduce multiple Bangs at different locations leading to adjacent shells from different Bangs interacting gravitionally with us, then the acceleration would be asymmetric in that direction.

When we look out into space it is not like Earth is a car on the street, it is more like we are on a boat in the middle of the ocean and all the other boats are accelerating away from us in all directions around us. If we look at the Cosmic Microwave Background Radiation which is like an afterglow from the Big Bang, then Earth is moving with respect to the ocean with the speed of ~627 km/s. When we measure the redshift of light from distant stars as a cosmological doppler, we notice that they currently recede from us with the speed of ~74 km/s/Mpc, the Hubble constant. Mpc stands for Megaparsec which is a distance of ~3.1×1013 km so the current value tells us that every second 1 meter is expanding with 74/3.1×1013= ~2.4 picometers and as comparison the smallest of all atoms have an estimated radius of 31 picometres. As Airbrush are saying the acceleration of expansion is caused by a force called Dark Energy that actively tries to push the Universe apart, but on close range the nuclear forces or gravity are much much stronger and resists this force, causing objects to settle into equilibrium at undetectable but slightly larger size.

According to observation time flows and things change, everything is affected and nothing remains the same. We don't have knowledge of anything able to continously restore or keep the Universe in a static steady state. Without a reasonable explanation of how the Universe can avoid changing I am in serious doubt of such claims. Any observational evidence or good logical arguments other than your opinion that it MUST be correct?

Was not this a test you have finished and as of which you now could ask your teacher for the intention and answer of the question? Or are you trolling and trying to stirr up fuzz?

Maybe I mixed it up too, lets try again: Since the speed of light is constant for all observers, when local time ticks slower deep down in the gravity well, for the local observer than for a distant observer, then local space should seem equally larger for a distant observer than for the local observer. So if an object that is 1 lightsecond long in flat space, is placed on Earth's surface it would locally take 1 second for light to go from one end to the other, but for the distant observer 1 Earth second is ~0.6963 nanoseconds longer. [math] t_{local}=t_{distant}*\sqrt{1-\frac{2Gm}{rc^2}} [/math] G = 6.67428×10-11 m3kg-1s-2 m = 5.9736×1024 kg for Earth r = 6 371 000 m mean for Earth c = 299 792 458 m/s Thus for the distant observer the clock ticks slightly more while the same lightsignal travel across the object which means that the distant observer also measures this object to be ~209 millimeters longer down on Earth than up in flat space. Which means that a straight cylinder in flat space moved down to Earth would appear to get streched slightly conical with its base diameter a little larger than its top diameter. In FLAT space the interior angles of a triangle always add up to 180 degrees and the circumference of a circle is always the diameter multiplied with pi. CURVED space is when those requirements are not fullfilled. As such flat space is where there is no influence of gravity at all and from there the curving increases with the strength of gravity. Locally you can't see the curving because it is a very tiny effect and since there is nothing to compare against when everything curves with space. If you bring your straight ruler there to check it will bend exactly as much as space making space seem straight. So curved space looks flat locally, it's when observers compare their local space and time with a different environment they see time dilation or length contraction. If an observer moves up and down in the cylinder placed upright on a gravity source then he and all equipment he brings with him will also be subjected to the warping of spacetime, so he will not be able to measure any different size locally of the cylinder. However if he measures the top and bottom diameter he would be able to see that the bottom is greater. Ok, it seems like I messed up, sorry if I turned things upside down for you. As said above the cylinder should be wider closer to the source of gravity and more narrow on the side towards empty space. Which means that from an outside view the media inside the cylinder would appear less dense closer to the source of gravity, before gravity compresses the media towards the bottom. I might have misinterpreted you but I think you are also getting into a hypothetical side effect of space warping instead of normal gravity and not only a confusion of pressure/equilibrium effects. Yes, there is a valid reason for submarines to have a maximum depth, however if the cylinder would be in freefall orbiting Earth the media can't feel any acceleration from the cylinder, but are still inside the range of Earth's gravity. The effect you seem to be targeting should make a difference here, very slightly increasing pressure towards Earth, se below. Well, I think we start to dip our toes in the speculation area now. My understanding of gravity in relativity is that objects follow straight paths through spacetime due to inertia and that the curving of space causes these straight lines to bend. I am not able to explain it better than that. The geometry of space does not change as you move through it, locally you can not measure any change and from the outside view the only change done to the field of gravity is caused by your mass, which is equal in both directions. However the geometry of spacetime is different closer to a gravity source, so the speculation part that random movement might slightly favoring wider space is beyond my knowledge, but I think if it exists it would be a very tiny side effect and not what we normally mean with the force of gravity. As said above, if this effect is real then it should be possible to verify it by experiment in orbit. Repeating/restating: - Curvature means that distances seems greater closer towards a gravitational mass from a distant observer's view. - Even if it space appears flat for the local observer, it's only flat without influence from gravtity. - When moving deeper into a gravity well, time passes more slowly and distanses increases from an outside view. - Local observers are not able to measure any difference since they don't have anything to compare against inside their frame of reference and in small enough areas space is approximately flat. The apparent change from different perspectives is unable to affect particles, the difference in geometry on the up and down side of the particle is independent of observers. From an external perspective we do see space curvature change significantly for the test particle moving through it. In the perspective of a moving particle space is not changing, everywhere along the cylinder the diameter will locally be of the same size but if space is highly curved then the diameter will appear to be greater in the down direction and smaller in the up direction from the current location.

Assume, I am no math expert and don't know any rule for this either. I guess for this cind of question the math is of such level that multiplication of 2 and y should have precedence. Well, I don't think the answer is 24×12, do you? [EDIT] Actually I think the general rules are to first perform any calculations inside parentheses and then multiplications/divisions take precedence before additions/subractions and priority is from left to right. However 48/2(9+3) is different than 48/2×(9+3) since the multiplication sign is significantly missing in the first equation. When it is removed I always intuitive put an extra parentheses around that part making it 48/(2×(9+3)) or 48/(2×y).

Otherwise it should have been: (48/2)y = 24y

Place the equation this way and it will be easier to see: [math]\frac{48}{2y}=\frac{24}{y}[/math]

Observable universe Both popular and professional research articles in cosmology often use the term "universe" to mean "observable universe". This can be justified on the grounds that we can never know anything by direct experimentation about any part of the universe that is causally disconnected from us, although many credible theories require a total universe much larger than the observable universe. No evidence exists to suggest that the boundary of the observable universe constitutes a boundary on the universe as a whole, nor do any of the mainstream cosmological models propose that the universe has any physical boundary in the first place, though some models propose it could be finite but unbounded, like a higher-dimensional analogue of the 2D surface of a sphere which is finite in area but has no edge. It is plausible that the galaxies within our observable universe represent only a minuscule fraction of the galaxies in the universe. http://en.wikipedia.org/wiki/Observable_universe Copernican principle In physical cosmology, the Copernican principle, named after Nicolaus Copernicus, states that the Earth is not in a central, specially favored position. More recently, the principle has been generalized to the relativistic concept that humans are not privileged observers of the universe. In this sense, it is equivalent to the mediocrity principle, with important implications for the philosophy of science. ... Measurements of the effects of the cosmic microwave background radiation in the dynamics of distant astrophysical systems in 2000 proved the Copernican principle on a cosmological scale. The radiation that pervades the universe was demonstrably warmer at earlier times. Uniform cooling of the cosmic microwave background over billions of years is explainable only if the universe is experiencing a metric expansion. http://en.wikipedia.org/wiki/Copernican_principle

Sounds like Homework for me, you can find all you need to solve the question here: Pascal.

But as DrRocket says, we don't know whats causing the effect of the cosmological constant.

First I wonder why you are asking here and not in the Relativity subforum? (IMHO, I think you would get more qualified answers by asking there.) Secondly I think you are mixing a lot of things: ¤ A uniform cylinder would continue to appear uniform for those inside it, when it gets "submerged" in gravity. ¤ An upright cylinder on Earth is more curved on the downside, so particles are moving toward the narrow side. ¤ Gravity itself is not a pressure/equilibrium action difference in a media, it acts individually on all particles. Like a moving object have a trajectory through space, all objects have a path they follow through spacetime and without gravity these paths are straight but gravity curve them towards its source. Objects in free fall follows those paths and objects forced out of their natural paths feel an acceleration. Particles in this uprised cylider have natural free fall paths that are curved downward by the gravity field of Earth and unless something is preventing them they will follow their paths. Since they are locked inside a cylinder their overall paths will be down towards the center of Earth, which will eventually get prevented by the bottom or other particles already resting on it or other particles stuck inbetween, causing an upright acceleration of 9.8g. All particles will stack on the bottom and up, leaving the upper part empty and putting lower parts under higher pressure. If the particles are part of a fluid or gas then the stacking procedure will be more complicated than for several individual solid particles, but the general tendency caused by gravity will be evident. If you want more detailed information you will need to read and learn about Geodesics and ask relativity experts.

How do you suppose any outer unsymmetrical shell is able to account for the observed symmetrical acceleration of expansion? And what cind of geometries do you imagine are possible outcomes when shells transformes from symmetrical spherical shapes? Not at all, any cind of shape, even a spherical shell with a totally empty inside will reverse and crunch if the escape velocity is not exceeded. (However current observation of an accelerated expansion makes a future reversal for our Universe very unlikely.) As already said, the size and composition of the stuff inside the shells is irrelevant, these objects are only tiny grains in the soup and as such not able to determine the overall shape of the membrane. Unless you are introducing objects larger than the End of Greatness and up to the size of the observable universe. The Universe is by definition a closed system and all parts inside it must comply to the laws of nature, in the realm of Newton mechanics. Momentum is conserved and the center of mass is located at the locus therefore it's impossible to disintegrate inherent gravitational symmetry. You need to present an explanation of how the whole foam of such shells can have huge flows, causing the shells to change into different shapes. (Objects coalescing into SMBHs only changes the lumpiness inside the foam but not its overall shape.) And then you have to explain how this new shape is able to cause the observed acceleration of expansion. Any collision between shells in your model would be very chaotic indeed and not like anything we observe right now.

Going back in time will place the dots closer together but never precisely on top of each other, so each dot will always look like the center of the Universe. Extrapolation of the expansion of the Universe backwards in time using general relativity yields an infinite density and temperature at a finite time in the past. This singularity signals the breakdown of general relativity. How closely we can extrapolate towards the singularity is debated—certainly not earlier than the Planck epoch. http://en.wikipedia.org/wiki/Big_Bang The earliest phases of the Big Bang are subject to much speculation. In the most common models, the Universe was filled homogeneously and isotropically with an incredibly high energy density, huge temperatures and pressures, and was very rapidly expanding and cooling. http://en.wikipedia.org/wiki/Big_Bang Maybe this explanation will be simpler than Wikipedia: Where was the center of the Big Bang?

It is an analogy and not a full scale model, of course it has problems and of course a lot of people will misinterpret it. If you can make a simple, better and catchy explanation accurately describing modern cosmology, you would surely become famous.

The balloon analogy describes a closed Universe curved up on itself, all of the three spatial dimensions of space is located on the surface. A common misconception is that the balloon is expanding into empty space that is "beyond the Universe" and that it is expanding from a single point in the center of the balloon. But the balloon analogy is a 2-dimensional model, and the center of the balloon and the space around are not part of the 2-dimensional Universe. In our 3-dimensional Universe, these points could only be reached by traveling in a 4th spatial dimension (not the time dimension of 4-D spacetime), but there is no evidence that this dimension exists. http://www.astro.ucla.edu/~wright/balloon0.html

According to the Big Bang theory there is no center or other fixed location inside the Universe that space is expanding from, space expands equally everywhere. I think this is correct, "Kepler saw this as an argument for a finite observable universe, or at least for a finite number of stars".

What? Are you really serious? Two flashlights will obviously shine with twice as much light and there is nothing stopping this light from traveling further in space. A lightyear is simply how long light manages to travel in one year in vacuum when it moves with lightspeed. (Yes we have been able to measure how fast light propagates.) It takes sunlight approximately eight minutes to reach Earth and definitely not 1000 years. Olbers paradox is not about newly created stars but about infinite number of stars that has together been shining on Earth for an infinite time.

The mass distribiution out there must be symmetric unless an outside force has acted upon the system. If you have a center of the Universe then you will also have the center of mass located there and if something there is exploding sending out matter in a huge spherical shell, all this matter together would have to continue to have the center of mass located there. When this expanding shell is so huge that our bubble of observable universe is much smaller than its thickness, which makes this shell very very huge, any individual pieces of matter coalescing and redistributing would be extremly tiny changes relative the size of the shell, even the largest structures we have so far observed, like the Sloan Great Wall, would only be a tiny spec of dust amongst the vast quantity of other specs inside the membrane of such a shell, as such the foam containing all those objects would still be spread out all around and surrounding the center. Since the center of mass is unable to move in a closed system, the whole shell in total must still be a symmetric shell surrounding the gravitationally center. If the explosion sends out a symmetrical shell, then only a symmetrical shell can eventually fall back, unless it was sent out faster than the escape velocity in which case it would never fall back. I said back in post #20 that if one shell is falling back in and colliding with another shell moving outward, then they can interact gravitationally when they get merged but there would not be any general acceleration outward caused by the outer shell. Some individual parts might get pulled outward but most would get pulled sideways. If your model have shells that changes shape then you need to explain how that is possible and describe the transfer to their new shape. Right now it seems that you are not able to describe how your model can explain the accelerated expansion. The Dark flow anomaly I posted does NOT have "patches" accelerating outward, it concerns a small and unexplained velocity in ONE direction. The explanation presented in the articles I linked to doesn't contain any mysterious unknown forces, they claim ordinary gravity from ancient times, you on the other hand has not yet presented a method for how regular gravity is causing this movement in an outward direction. Well, maybe if you read my post more carefully you will see that I did mention that your model has more important problems to deal with first, but obviously a limiting speed of gravity will also put some restrictions on your model. Gravity is of course continuous, without any strange gaps and reaches infinite far, however gravity is NOT steady, objects can loose or gain mass and move around in space. Furthermore in modern cosmology very distant objects can recede much faster than light causing a horizon both for light and gravity, beyond which we can not observe or measure anything, but I have already mentioned that I am not interested in venturing into relativity in this thread. ¤ The Sun is burning fuel to shine so the energy released decreases its mass and therefore also lowers the strength of gravity. If we would be able to visually measure the size of the Sun with such precision that we could measure its mass, would we then see it as massive as it is pulling on us or would we see a more massive Sun than what its gravity affects us? If light reaches us with the same speed as gravity then we will see the image of the Sun matching its strength of gravity and if gravity is instant then we will see the image of a more massive Sun than the measured strenght of gravity. ¤ The Sun is not fixed in an absolute location in space, the Sun is moving and if the source of gravity is changing location the question arises whether we are observing the Sun in the direction where its gravity are pulling us or if we are viewing it where it was eight minutes ago and being pulled towards where the Sun actually is right now? If light reaches us with the same speed as gravity then we will see an image of the Sun where its gravity is currently pulling us but if gravity is instant then we will see the image of the Sun lag behind its direction of gravitational pull. According to Relativity gravity propagates with the speed of light which means that distant images that reaches us have the same age as how those objects gravity affects us. As such we see objects as they where when their gravity was emanated and in the same direction that their gravity is pulling us. Conclusion is that if distant objects are able to affect us with their gravity then we are also receiving light from those objects and since both light and gravity weakens with the inverse-square law, objects to dim to observe can't really be affecting us much gravitationally, unless you want to add something obscuring the shells from each other. This also reminds me that you might have to many and to large shells giving you a fourth problem with Olbers paradox. There is no need to rush a reply if you are short of time, the thread will be here waiting for you.

You really should read the link presented: The Paradox The paradox is that a static, infinitely old universe with an infinite number of stars distributed in an infinitely large space would be bright rather than dark. To show this we divide the universe in to a series of concentric shells, 1 light year thick (say). Thus a certain number of stars will be in the shell 1,000,000,000 to 1,000,000,001 light years away, say. If the universe is homogeneous at a large scale, then there would be four times as many stars in a second shell between 2,000,000,000 to 2,000,000,001 light years away. However, the second shell is twice as far away, so each star in it would appear four times dimmer than the first shell. Thus the total light received from the second shell is the same as the total light received from the first shell. Thus each shell of a given thickness will produce the same net amount of light regardless of how far away it is. That is, the light of each shell adds to the total amount. Thus the more shells, the more light. And with infinitely many shells there would be a bright night sky. http://en.wikipedia.org/wiki/Olbers'_paradox

Don't forget that he was running naked with a hard on to share his discovery.

While I wholeheartedly agree with your arguments, I strongly disagree with your recommendation, from my experience and knowing myself, I think people in general are to unalert, lazy and sloppy to properly find and report bad language to any substantional level. If the system allows it then levels will rise slowly and we will become more and more used to it.

Yes I agree, the life there would be very hard indeed, but IF we find out that the conditions there are good for Earth life, otherwise than for the strong gravity, then Earth life will survive and adapt naturally with time, IF we are able to bring it there, no immediate need for bioengineering. Of course since Gliese 581g is NOT just a simple more massive Earth I would suspect that the "other conditions" for Earth life is NOT good at all and might require massive bioengineering or expensive terraforming if even possible at all. Finding a planet like in the science fiction movie Avatar does not seem very likely, but the thoughts of one similar to Earth is very intriguing even without intelligent aliens.

Your question has been answered already back in post #2 and post #4. You have not confirmed the evidence presented in post #2 and post #4. ---------- I have three obvious basic major problems with your model and have so far only touched upon one, Iggy brought up the second and the third is about the CMBR. The speed for gravitational propagation that md65536 is presenting might be a further problem, but your model needs to survive all basic problems with standard Newton mechanics before there is any point in continuing into more advanced problems. ---------- Problem I: The observed acceleration of expansion. I will presume that your model is unable to explain the observed acceleration of expansion, since you have not presented any valid method for the phenomena. ---------- Problem II: The observed expansion is isotropic. I am not yet able to understand how you model is able to explain for the observed isotropic expansion, can you please provide an detailed explanation of this?

Gliese 581g could be up to 4.3 times as massive than Earth but the surface gravity is not expected to be higher than 1.7 times of what we have. Surface gravity depends on mass and radius and while a 4 times more massive sphere with roughly the same density would only have a cubic root of 4 greater radius, gravity gets weaker with the square of that change in radius, making surface gravity there 4/42/3= ~ 1.6 times that of Earth. A 70 kg. person would not likely weight more than 120 kg. and probably only around 110 kg. which would limit capabilities, but not make it impossible to live there. Physical characteristics Gliese 581 g has an orbital period of 37 days, orbiting at a distance of 0.146 AU from its parent star. It is believed to have a mass of 3.1 to 4.3 times Earth's and a radius of 1.3 to 2.0 times Earth's (1.3 to 1.5 times larger if predominantly rocky, 1.7 to 2.0 times larger if predominantly water ice). Its mass indicates it is probably a rocky planet with a solid surface. The planet's surface gravity is expected to be in the range of 1.1 to 1.7 times Earth's, enough to hold on to an atmosphere likely to be denser than Earth's. http://en.wikipedia.org/wiki/Gliese_581_g