Starship Asterisk*

harry wrote:G'day from the land of ozzz

You got to know that, I'm not a smart cookie.

makc wrote:your reasoning is like that in the tale of Achilles and the Tortoise. it is true that f(x) = exp(-x) will never reach 0, but g(x) = 1 - x will reach g=0, cross it, and extend forever into negativity. so I am asking here what makes you think it is f(x) situation, and not g(x)?

...As we now show, if w < −1 persists, then the fate of the Universe is quite fantastic and completely different
than the possibilities previously discussed.

To begin, let us review these other fates. In a flat or open Universe without dark energy, the expansion continues forever, and the horizon grows more rapidly than the scale factor; the Universe becomes colder and darker, but with time the co-moving volume of the observable Universe evolves so that the number of visible galaxies grows.

If the expansion is accelerating, as a consequence of dark energy with −1 ≤ w < −1/3, then the expansion again continues forever. However, in this case, the scale factor grows more rapidly than the horizon. As time progresses, galaxies disappear beyond the horizon, and the Universe becomes increasingly dark. Still, structures that are currently gravitationally bound, such as the Milky Way and perhaps the Local Group, remain unaffected. Thus, although extragalactic astronomy becomes less interesting, Galactic astronomy can continue to thrive.

Chris Peterson wrote:...there's no way in that case to distinguish between a photon of zero energy, and the simple absence of the photon.

Chris Peterson wrote:The redshift ends up simply as Z = [a(t1) / a(t0)] -1, where a(t1) is the cosmological scale factor when the redshift is measured, and a(t0) is the cosmological scale factor when the photon was emitted. The value a(t) is assumed by theory (supported by observation) to be monotonically increasing with time. This cosmological redshift can't become infinite except in the limit of an infinite length of time.

makc wrote:unlocked per request. feel free to spam the forum

makc wrote:it's getting hard to read through hundreads of genuine posts here well, as long as I, let's say, misunderstood you, feel free to.. whatever.

harry wrote:Hello Qev

Actual Time cannot change, relative time can because the speed of EMR can be altered during experiments here on earth and when EMR comes close to compact object...

Abstract: The question of determining the spatial geometry of the Universe is of greater relevance than ever, as precision cosmology promises to verify inflationary predictions about the curvature of the Universe. We revisit the question of what can be learnt about the spatial geometry of the Universe from the perspective of a three-way Bayesian model comparison. We show that, given current data, the probability that the Universe is spatially infinite lies between 67% and 98%, depending on the choice of priors. For the strongest prior choice, we find odds of order 50:1 (200:1) in favour of a flat Universe when compared with a closed (open) model. We also report a robust, prior-independent lower limit to the number of Hubble spheres in the Universe, N_U > 5 (at 99% confidence). We forecast the accuracy with which future CMB and BAO observations will be able to constrain curvature, finding that a cosmic variance limited CMB experiment together with an SKA-like BAO observation will constrain curvature with a precision of about sigma ~ 4.5x10^{-4}. We demonstrate that the risk of 'model confusion' (i.e., wrongly favouring a flat Universe in the presence of curvature) is much larger than might be assumed from parameter errors forecasts for future probes. We argue that a 5-sigma detection threshold guarantees a confusion- and ambiguity-free model selection. Together with inflationary arguments, this implies that the geometry of the Universe is not knowable if the value of the curvature parameter is below |Omega_curvature| ~ 10^{-4}, a bound one order of magnitude larger than the size of curvature perturbations, ~ 10^{-5}. [abridged]

makc wrote:it is easy to say, photon was consumed, and the energy was used to move electron into higher orbit, and then forget about it; but if you keep thinking about it, where does photon go?

bongman wrote:Would the local conditions of a supernova be similar or equal to those found at a "big bang"? For the first 10^-43 would the area be domintated with Radiation and Plasma? or are these explosions not thought to be that powerful?

JimJast wrote: "...Since energy can't be neither created nor destroyed. And the "gravitational force" and "the curvature of space" is the proof of that, but it is another story.

mark swain wrote: All i can say to this, there,s a lot we don,t understand, there are things we can,t see to explain why we don,t...

all the evidence is not there to see,, But there is evidence of some things, which makes us want to know why?

Anybody else lost a bone round here?

Mark

Abstract: In loop quantum cosmology, the universe avoids a big bang singularity and undergoes an early and short super-inflation phase. During super-inflation, non-perturbative quantum corrections to the dynamics drive an inflaton field up its potential hill, thus setting the initial conditions for standard inflation. We show that this effect can raise the inflaton high enough to achieve sufficient e-foldings in the standard inflation era. We analyze the cosmological perturbations generated when slow-roll is violated after super-inflation, and show that loop quantum effects can in principle leave an indirect signature on the largest scales in the CMB, with some loss of power and running of the spectral index.

aristarchusinexile wrote:And yet .. the mysterious 'replusive force' which some say is driving the universe apart, if it is a force, must be energy, and seems to be in the process of constant creation.

Chris Peterson wrote:

aristarchusinexile wrote:And yet .. the mysterious 'replusive force' which some say is driving the universe apart, if it is a force, must be energy, and seems to be in the process of constant creation.

I don't understand in what way dark energy is in "constant creation". The energy budget of the Universe is fairly well defined, and there's nothing I'm aware of that suggests the total energy is changing.

mark swain wrote:Biography
Prof. Dr. Dr. h.c. Kenneth J. Hsu,

Got to tell you mate, Biography of Dr Kenneth is not easy reading. And the three who rejected his paper maybe thought the same. The great distance of time/Matter is like a Maze, a giant Computer program waiting to be solved. If any one of the great, get it wrong, how many will get to the same dead end?

Mark

http://www.sdss.org/includes/sideimages/sdss_pie2.html wrote:

Slices through the SDSS 3-dimensional map of the distribution of galaxies. Earth is at the center, and each point represents a galaxy, typically containing about 100 billion stars. Galaxies are colored according to the ages of their stars, with the redder, more strongly clustered points showing galaxies that are made of older stars. The outer circle is at a distance of two billion light years. The region between the wedges was not mapped by the SDSS because dust in our own Galaxy obscures the view of the distant universe in these directions. Both slices contain all galaxies within -1.25 and 1.25 degrees declination.
Credit: M. Blanton and the Sloan Digital Sky Survey.