Speed of light

[aristarchusinexile]

G'day from the land of ozzz

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

Harry, if you're not a smart cookie I'm a dumb crumb.

[makc]

unlocked per request. feel free to spam the forum

[Chris Peterson]

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)?

You can derive the equation for cosmological redshift using GR geodesics. 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. (Careful with those examples... we're considering infinite redshift, not zero or negative redshift.)

The situation is different for a gravitational redshift. That is described by a completely different equation, and does become infinite at the event horizon of a mass singularity. But from a physical standpoint, this is also equivalent to the photon being trapped. In other words, there's no way in that case to distinguish between a photon of zero energy, and the simple absence of the photon. Of course, what is actually going on right at the event horizon is not well defined by current physics.

(I'm at Cambridge, UK right now, so my posting times are rather shifted from usual. Sorry... I know it makes for a rather stilted conversation.)

[makc]

in the meantime I digged out big rip paper. an interesting quote comes from the page two:

...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.

so, if dark energy exists, galaxies will leave visible universe; it appears, we do not even need "phantom energy" and Big Rip, right?

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

this might sound not really scientific, but I was just thinking about simple effect like hydrogen atom consuming photon and getting excited about it - if Einstein (or anyone else) would succeed to build the theory describing electromagnetism with space curvature effects, does this situation not have to be exactly that - red-shifting photon to 0 energy? I mean, 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? how come it is magically dissolved? what about "nothing comes into/out of nothing" postulate, that have never failed us before? if we are ready to give it up just like that in this case, why not just as well accept that photon can be wiped out of reality on the edge of visible universe, or some other region with exotic curvature of space?

edit:

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.

ha ha, this is on wiki. well, that means the above scenario assumes different metric, let's see if I can find it.... wait a minute, it has that part "For very small variations in time (over the period of one cycle of a light wave) the scale factor is essentially a constant", maybe that's not really true in that case, so simple formula for z doesnt work any more?

[aristarchusinexile]

unlocked per request. feel free to spam the forum

Thanks, Makc .. but this is not spam, this is genuine interest, about a seemingly genuine guy about a seemingly genuine topic.
Here are some google obtained urls. I can't understand the first symbols of the equations, but if anyone can, I'd appreciate their explanation.
http://www.springerlink.com/content/08082jmwu7256586/
http://www.springerlink.com/content/111637862493u00n/
http://prola.aps.org/abstract/PR/v69/i11-12/p608_1
http://www.goodreads.com/author/show/17 ... _Caldirola

And this one http://twgeoref.moeacgs.gov.tw/storage/ ... 64/EAB.PDF is particularly interesting, suggesting Chronons as the elementary particle in space and time. The author's (not Cardrioli in this case) credentials are very impressive. http://home2.btconnect.com/KennethHsu/biography.htm

[makc]

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.

[aristarchusinexile]

Another of my wierd, impossible thoughts .. I've read that gravity is not yet understood (?) If photons lose all their energy, instead of simply disappearing, might they absorb some kind of unknown energy, and convert to 'gravitons' (?)

[aristarchusinexile]

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.

I don't envy you your duties, Makc .. I find it hard to read the intention behind some posts, and of course I find it impossible to understand the content of many posts.

[Qev]

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...

What frame of reference are you going to use to define 'Actual Time', though? I'm going by the assumption that you're suggesting some variation of Newtonian dynamics, where some 'absolute' frame of reference exists?

[The Code]

http://tao.cgu.org.tw/pdf/v72p239.pdf

Chronon

A chronon is a proposed quantum of time, that is, a discrete and indivisible "unit" of time as part of a theory that proposes that time is not continuous. While time is a continuous quantity in standard quantum mechanics, many physicists have suggested that a discrete model of time might work, especially when considering the combination of quantum mechanics with general relativity to produce a theory of quantum gravity.

One such model was introduced by P. Caldirola in 1980.[1] In Caldirola's model, one chronon corresponds to about 6.97×10−24 seconds for an electron. He claims the chronon has important implications for quantum mechanics, in particular that it allows for a clear answer to the question of whether a free falling charged particle does or does not emit radiation. This model supposedly avoids the difficulties met by Abraham-Lorentz's and Dirac's approaches to the problem, and provides a natural explication of quantum decoherence.

From Wikipedia, the free encyclopedia


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

[harry]

G'day from the land of ozzzzzz

Apply the black box approach.

What ever happens within the Gyr box cannnot effect time outside.

You cannot alter time in one area and not effect time in another.

[harry]

G'day from the land of ozzzzzz

This link is quite interesting


http://arxiv.org/abs/0901.3354

How flat can you get? A model comparison perspective on the curvature of the Universe

Authors: Mihran Vardanyan (Oxford), Roberto Trotta (Imperial College London), Joe Silk (Oxford)
(Submitted on 21 Jan 2009)

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]

[JimJast]

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?

A photon is a package of energy. If electron gets on "higher orbit" the photon is this energy that electron gained. It changes only its name from "photon" to "increase of energy". Then, when electron drops to "lower orbit" a photon is emitted. It is not the same photon and (on rara occasions)it may have even different energy since the electron might drop to "much lower orbit" or "a little bit lower orbit". Depenting on that the new photon will have bigger or smaller energy than the original photon. Most of the time the same sice most of the time the electron just drops to the previous "orbit" (energy level). What has to be the same is only the energy that gets in and out. 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.

[Doum]

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?

I dont think that the condition are similar. Big bang is an explosion of the spacetime. And supernova is only a star explosion.

[harry]

G'day from the land of ozzzz

Supernova in many cases involves the formation of a jet from the combination of the core and the infalling disc matter. The PINCH of the magnetic fields form a hughe amount of Neutrons which change back to H instantaneously.

So! Maybe the process could resemble the BB process.

Closer to the BB process is:
The huge Jets formed by HUge mega jets are of a similar nature that involve denser transients like quark composites and Neutrino matter. The jets from these can seed star clusters that eventually may form dwarf galaxies.

You can google for the info.
If you want information on this just ask.

[aristarchusinexile]

"...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.

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.

[aristarchusinexile]

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

Mark, did you check these two urls out? Absolutely fantastic about the possibilities.
http://twgeoref.moeacgs.gov.tw/storage/ ... 64/EAB.PDF is particularly interesting, suggesting Chronons as the elementary particle in space and time. The author's (not Cardrioli in this case) credentials are very impressive. http://home2.btconnect.com/KennethHsu/biography.htm

[The Code]

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

[harry]

G'day from the land of ozzzzzzzz

When I posted the last post, I was looking for this link.

http://arxiv.org/abs/astro-ph/0311015
Loop quantum gravity effects on inflation and the CMB

Authors: Shinji Tsujikawa (Portsmouth), Parampreet Singh (IUCAA), Roy Maartens (Portsmouth)
(Submitted on 2 Nov 2003 (v1), last revised 21 Oct 2004 (this version, v3))

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.

It is well documented of the power of the mega jets found in large galaxies and in the centre of clusters of glaxies. These jets eject matter that start star formation and and reform galaxies and galaxies afar.

[Chris Peterson]

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.

[aristarchusinexile]

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.

I guess we're reading different information, Chris .. and of course my unorthodox views will not allow me to see as "infallible" the theory that energy cannot be created or destroyed .. and while the following paragraph is mere musing I will suggest that Coulomb's Law as well as energy budget can be 'overcome' (in the loose sense of that word) if the spin of spirals creates the 'repulsion' (although I don't like that word) creates the energy which moves galaxies and groups apart as if they were balloons separated by like-charges. Also, I suggest the possibility that instead of the theoretical Dark Matter reducing the charge between galaxies ("If the charged objects are present in water, the value of k can be reduced by as much as a factor of 80) DM may add to the energy, accounting for the increasing rate of expansion the further out we go. Of course, we would then have to explain why groups of galaxies form if spirals are creating division, and while admitting I haven't of course examined many galaxies or groups, I suggest that that the non-spiral galaxies, for instance those surrounding our Milky Way, may inhibit the energy which separates spirals, allowing Andromeda and Milky Way to draw together, but with the seeming preponderance of spirals in groups would create the hypothectical energy which separates the groups, causing the expansion .. and that we are really just beginning to understand energy, I think, is illustrated by this:
TIME AND SPACE
Researchers Measure Elusive Repulsive Force From Quantum Fluctuations

Here are researchers Jeremy Munday, Postdoctoral Scholar, California Institute of Technology, and Federico Capasso, Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering at the Harvard School of Engineering and Applied Sciences. Credit: Eliza Grinnell, Harvard School of Engineering and Applied Sciences.
by Staff Writers
Boston MA (SPX) Jan 13, 2009
Researchers from Harvard University and the National Institutes of Health (NIH) have measured, for the first time, a repulsive quantum mechanical force that could be harnessed and tailored for a wide range of new nanotechnology applications.
The study, led by Federico Capasso, Robert L. Wallace Professor of Applied Physics at Harvard's School of Engineering and Applied Science (SEAS), will be published as the January 8 cover story of Nature.
http://www.spacedaily.com/reports/Resea ... s_999.html

[aristarchusinexile]

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

Exactly why we shouldn't accept theory as fact, like Big Bang for instance .. and the fact that it's accepted as fact by many is obvious from the many books which begin with the Bang, eg. 'No one knows what existed before the Big Bang.' However, I admit I view my anti-gravity bubbles causing the expansion nearly as fact, so I guess I'm as human as any other man in love with Anita Ekberg, or that blonde I met the other day, or anyone who appreciates a slice of good pizza when they're hungry.

[aristarchusinexile]

(Hoping this is not in violation of copyright .. it is funded from Nasa).
From time operator to chronons
Misra, B.
Foundations of Physics, Volume 25, Issue 7, pp.1087-1104
A time operator, which incorporates the idea of time as a dynamical variable, was first introduced in the context of a theory of irreversible evolution. The existence of a time operator has interesting implications in several areas of physics. Here we demonstrate a close link between the existence of the time operator for relativistic particles and the existence of an indivisible time interval or chronons for dynamical evolution. More explicitly, we consider a Klein-Gordon particle and require the existence of a time operator for its evolution. We also make a natural choice of the form of the time operator which expresses it in terms of the generators of the Poincaré group. These then imply that the physical time evolution group must be the discrete subgroup Unτ (n integers) of the originally given evolution group Ut of the Klein-Gordon particle and the constant τ is given by τ=h/2mc2. This means that the requirement of the existence of a time operator implies that the time evolution cannot be followed to time intervals smaller than τ and, as such, τ emerges as a chronon for the dynamical evolution. Expecting that the same results hold for a Dirac particle also, we conclude that the so-called Zitterbewegung does not occur in reality. Thus, possible confirmation of the existence of chronons would result if no observable consequence of Zitterbewegung is actually realized in nature. This calls for a search of observable consequences of the Zitterbewegung and a re-examination of their agreement (if any) with experiments. A possible consequence of Zitterbewegung, the so-called Darwin term present in the Dirac Hamiltonian in an electric field, is briefly considered.
DOI: 10.1007/BF02059527
The ADS is Operated by the Smithsonian Astrophysical Observatory under NASA Grant NNX09AB39G

[neufer]

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.

[aristarchusinexile]

Wow! Earth really IS at the centre of the universe after all!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!