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Explore the latest questions and answers in Physical Cosmology, and find Physical Cosmology experts.
Questions related to Physical Cosmology
Could anyone define and explain the concept 'virtual' in Quantum Physics, Cosmology, Metaphysics, and Artificial Intelligence? Or, do such definitions exist?
Would any such transition have occurred in increments locally, or all at once globally?
Is the idea of the transition from one era to the next designed to save an unlikely or incomplete theory?
Are there articles discussing these questions?
RS:How does the universe know when to transition from radiation dominated ... to matter dominated ...
Robert Shour, the attached graph shows the energy density of the three components, the evolution of the scale factor depends on the combination of all three so there isn't a sharp transition but a smooth curve between them.
RL: The recent observation by the JWST of galaxies older than 13.79 billion years ...
Richard Lewis, that has not happened, galaxies have been seen at high redshift than previously but they are still about 170 million after the fiducial start, so about 13.62 billion years ago. They are very small as predicted, the surprise is that some are less unstructured than anticipated. There will be galaxies found even earlier than these but probably not before 13.76 billion years ago.
Do such measurements make sense? Do they exist?
Comparing redshift and luminosity distances, if that is a sensible question, may bear on the 4/3 scaling hypothesis as it relates to dark energy.
From the 1998 book Seeing Red by Halton Arp, at page 274.
Is that consistent with nullius in verba?
Do you agree with Halton Arp?
Cosmological explanations for our apparently fine-tuned universe are basically divided between a) a vastly huge multiverse of universes with varying fundamental force and mass constants, including the cosmological constant (where our apparently fine-tuned universe is just one universe in this multiverse), or b) a cosmic intelligence that fine-tuned our universe at its beginning to evolve stable galaxies, life and developed minds. In scientific terms, which explanation is preferable? Are there other options? Is a cosmic mind a viable scientific hypothesis for explaining our universe's origin?
Should the scholars at RG and elsewhere be alarmed by the press reports on the influence of the unholy alliance of big money and theology on high-value scientific research, particularly on theoretical physics and cosmology?
The British newspaper, The Guardian report: The MIT-Epstein debacle shows ‘the prostitution of intellectual activity’. https://www.theguardian.com/commentisfree/2019/sep/07/jeffrey-epstein-mit-funding-tech-intellectuals
BBC reports:
Big Bang and religion mixed in Cern debate
Big Bang: Is there room for God?
More on how Big Money, Beauties, "Big Minds" and Big Science converge:
The foundation of physically reality is necessarily very simple and quite probably its structure cannot observed. But recently I came to the conclusion that the signature of this foundation can be observed in all aspects of the universe. All separated items in universe are either modules or modular systems.
Is modular configuration a fundamental characteristic of physical reality?
Cosmology is difficult because space, time and the sizes of cosmological things are at scales vastly larger and smaller than are easily perceived by human beings. To guess what the universe is like requires extrapolations. But extrapolations are based on the assumption that what we can witness, see and measure corresponds to what we can’t witness, can’t see and can’t measure. Is cosmology science? Is it a science-in-waiting? Does cosmology become science when its ideas are confirmed by astronomy?
It is commonly accepted that General Relativity has its own 'bare' cosmological constant that contributes together with the cosmological constant resulting from vacuum energy density for an effective cosmological constant. Are there any candidates for this 'bare' cosmological constant?
According to Weyl and Chandrasekhar, general relativity (GR) is a triumph of speculative thought. But it is a well-known fact that GR is initiated by two analogies. Analogy is known to be a weak reasoning in science and philosophy. To redress the case this type of reasoning is renamed as Equivalence Principle (EP) in relativistic physics. The renaming, however, could not hide the fact that the presented analogy was not flawless. Irrefutable disproves were side-stepped and the analogy was instated to be the seed of new kind of physics. EP was defended by reducing the size of the lab and the duration of the experiment. This type of defending is like the proponents of flat-earth idea defend their case by reducing the patch of the land for examination until their pseudo-science theory is proven.
The attached document is a short description of EP analogies and its well-known critics. The document also introduces a new EP based on Uniform Deceleration of a spaceship in open space. This new analogy results in a different curvature of light in comparison to what original EP has established using uniform acceleration. The author believes that none of the conclusions from EPs should be allowed in science as they are based on inconclusive comparison/analogy and they ignore glaring flaws in the argument.
The author would like to present this new EP for discussion and criticism.
Should a manned mission to Mars, which could be implemented in a few years, be an international mission, or rather a national one, inspired and organized according to the familiar concept of the 1970s, of international rivalry of the leading economically and politically largest countries?
Apparently a manned mission to the planet Mars is now technically possible.
Researchers working on space exploration programs argue that it is technically possible that humans already have the necessary technology to carry out a two-year manned mission to Mars.
First of all, it is necessary for the US President to issue a program of a manned mission to Mars.
A similar program in the 1980s was announced by then US President John F. Kennedy.
The plan of a manned mission to the moon was fully realized at that time.
However, the current mission to Mars, technically possible, would require large financial outlays for the implementation of this mission.
Perhaps it would be necessary to organize an international consortium that would organize an international manned mission to Mars.
Maybe it could also be an international crew of this mission?
Then mission costs could be spread over several countries and it would have global significance in terms of international cooperation.
The previous analogous manned space mission, i.e. the manned expedition to Earthly Princes in the 1970s, had the significance of political rivalry between the then US and the Soviet Union.
It was a symbolic technological race.
Is the planned manned mission to Mars also inspired by this type of international competition, for example between the US and China or possibly also some other countries?
China is rapidly developing technologically, aspiring to become a global powerhouse in a few years time. 1 not only in the scope of production of various goods and economic growth but also in the matter of having the most modern innovative technologies implemented in various economic applications.
In the US, a very large, historically high public debt can be a significant finns barrier to finance and thus the USA will organize a manned mission to Mars in the next few years.
If this mission to Mars is mainly inspired by this new international rivalry in terms of having technological capabilities, it is currently difficult to predict which country will win the race and be the first to organize manned missions to Mars?
In view of the above, I ask you with the following question: Should a manned mission to Mars, which could be implemented in a few years be an international mission, or rather a national one, inspired and organized according to the familiar concept of the 1970s, of international rivalry leading economically and politically the largest countries?
Please reply. I invite you to the discussion
Suppose there is a static 3 dim space and a dynamic changing 4 dim space. Without that supposition, lots of problems in physics remain puzzles. With it, lots of puzzles are easily resolved.
Energy in 4 dimensional space, where the fourth dim is proportional to the distance light travels or the time it takes for light to travel that distance, has 4/3 as much energy per dimension as does 3 dim static space. Hence, dim space a 4/3 length L when 4 dim space has a distance of length L. This appears to account for space expanding. A supernova’s distance from Earth measured in the 4 dim space where light moves, using redshift, should appear to be 3/4 as luminous when comparing type 1A supernovas, because in static 3 dim space the supernova is 4/3 as far. Other data is consistent. Energy density for dark energy (so called) compared to matter energy density is in the ratio [ E/ L^3] : [ E/ {(4/3)L}^3, which is 4^3/3^3 which is about 0.7033/ 0.2967, as has been observed in astronomy.
There are numerous examples of this 4:3 ratio occurring a variety of different natural phenomena, as set out in various article in my projects dealing with the 4/3 laws and DE.
Or maybe not?
It has radically altered it by rehabilitating Fritz Zwicky 1929.
Hence ten Nobel medals are gone. And cheap energy for all is made possible. Provided, that is, that humankind is capable of mentally following in Yakov Sinai’s chaotic footsteps. If not, energy remains expensive and CERN remains dangerous to all: A funny time that we are living in. With the crown of Corona yet waiting to be delivered.
April 1st, 2020
Dear Colleagues,
I am a liaison (informal) at my university between science and the arts. I have family in planetary astronomy but this is far afield.
LINK to VIDEO: https://news.harvard.edu/gazette/story/2020/01/largest-gaseous-structure-ever-seen-in-our-galaxy-is-discovered/
A question or two:
What does this newly-reported Radcliffe Wave of gaseous proto-stars tell us about how our galaxy originated?
Is there any chance that this wave will make some difference in our own sun's behavior?
I want some help in being able to clearly perceive the expansion of the universe and the consequences thereof.
We know that the universe is expanding in an accelerated manner. It is my understanding that space alone cannot expand without affecting the local time. Thus as per GTR, depending on the curvature of space-time and the energy density, time too shall suffer a change due to the changing space.
Assuming that there is no curvature of space-time and no mass or energy contained in a chunk of space (assuming the zero-point energy of empty space as zero) between two galaxies A and B, let us say that the local time at a point P in this space goes as t0. If we on Earth could somehow observe this point and measure the time at P as t,
- When we talk about the rate of expansion for example as in Hubble's Law, do we follow the comoving coordinates or the proper coordinates?
- How would t and t0 relate to each other if the rate of expansion is uniform and accelerating respectively?
- How much is 1s for the comoving observer at the inflation period in terms of the usual 1s now on Earth?
This question requires explanation. Discussion on the second day of Galileo’s Two Chief World Systems raises the point.
Simplicio, taking the position of those opposed to Copernicus, doubts the Earth moves; if Earth moved it would have to move at too great a speed. Sagredo and Salviati say this objection has no merit. The fixed stars have a radius far greater than the Earth, and yet the implied speed, much greater than that of the Earth in the Copernican conceptual reference frame, does not undermine the belief of the anti-Copernicans in their objection. Here is an inconsistency.
The inconsistency is not encountered in modern times that takes for granted the heliocentric model of the solar system. This argument, based on the large radius of the distant stars, is one not usually encountered. One supposes that is so, because it is unnecessary. But then the question arises. Does society lose or forget these old insights that are discarded once new conceptual reference frames take hold? Or, perhaps, is nothing lost?
Dear all,
in accordance with Friedmann-Lemaitre-Equation there are three different possibilities of space curvature which can be described mathematically and imparted graphically or analogously (Closed, Openend or Flat Universe). In the attached poster a fourth graphic representation is shown, which is however only graphically derived.
Is this sketch describable within Friedmann-Lemaitre-Equations? How can we interpret this sketch? A Universe that is truly infinite, although it has a defined start and a defined end point?
What would be a 3-Dimensional mathematical object to describe the plot (closed hypertorus, while closed means without a connection in the center?). And what numbers for curvature parameter k and density Parameter Ω make sense for this sketch?
I have created this plot purely graphically and wonder whether a mathematical interpretation of such a shaped space-time is possible, or whether it inevitably leads to paradoxes and is thus a graphic that can be drawn abstractly, but ultimately makes no mathematical sense.
Thank you!
Dimension is fundamental. Was it present at creation of the universe? Did it play a role in creation of the universe?
I have found two different results for the effect of dark matter on the orbital speed of the Sun. One from Wikipedia suggests there is no effect while another one from astronomynotes suggests there is a substantial effect. Which one is correct? Both Figures and their captions are attached.
The universe as a whole is much larger than the portion we can measure. That "observable universe" (OU) has a proper radius of around 43 billion light years. The Planck mission measured the curvature density ΩK of the OU as 0.0±0.005. For the positive 1 sigma value, that suggests the whole would be a 3-sphere with a radius of ~210 billion light years but inflation suggests the curvature should be much closer to zero, hence the whole would be far larger, probably many orders of magnitude. For zero or negative curvature, the spatial extent would be infinite.
If we assume that the whole is much larger than the observable portion, we could think of many alien species scattered throughout the universe but so widely separated that there is no overlap between their respective OUs. While the universe would have a mean curvature density, there are also statistical variations, so we can think of producing a histogram of the values of ΩK for all these uncorrelated regions, each around 43 billion light years in radius.
The Harrison-Zel'dovich spectrum tells us the two-point correlation of density as a function of separation of sample points. Specifically, it would be a power law with slope 1 but quantum effects predict a slightly smaller value and it has a measured slope of 0.96 (Planck mission results, 2015). The same results also gave a null result for "running" of the spectrum, which means it appears to be linear, no quadratic term, and there is no evidence of non-Gaussianity, which means the distribution can be assumed to be the standard bell curve.
My question is: what would be the standard deviation of the samples of ΩK measured over a large number of non-overlapping regions, each the size of our observable universe?
If anyone needs more background, I can provide links to introductory articles and some undergraduate lectures. This is the relevant section in the Planck results paper:
P.S. If you don't accept the standard model of cosmology or have your own alternative, don't waste your time replying, I am looking for a purely mathematical answer based on the conventional model.
Geodesics in a curved finite space are not parallel. Volumes transported over cosmic distances therefore will alter their shape and orientation in respect to initial conditions. If compared with the initial condition, the volume length in direction towards a receiver becomes increased during the transport; the receiver of radiation out of that volume will notice a red shift and a time dilatation. His immediate impression will be that an according expansion of the universe must have occurred. But it was only a curved space effect, which has caused a modification in shape, extension and orientation of the volume filled with radiation.
Could this answer some of the unsolved problems in cosmology?
C.f. Wikipedia; List of unsolved problems in physics; Cosmology and general relativity
Cosmic inflation
there is no cosmic inflation, the geometry of the universe is static.
Horizon problem
there is no horizon problem. The universe is closed. If we continuously go in any direction we finally will arrive at the starting point.
Origin and future of the universe
there is no origin, the universe is and stays eternal.
Size of the universe
the size is finite and can be determined from the length dilation on volume transport and the according red shift numbers.
Baryon asymmetry
the universe always had been filled with baryonic matter. Black holes are involved in coordinated recycling processes.
Dark anything
gravitational influence must be recalculated based on the static, finite, isotropic and homogenous geometry. In analogy to geometric influence on transported light, an influence on transported matter may exist. The deformed view on the transported images of galaxies also requires recalculations.
Axis of evil/Copernican Principle
the problem does not exist because the microwave background looks about the same in any direction at any place in the universe.
Shape of the universe
mathematically the shape of the universe can be described by a mapping of finite Cartesian coordinates to unit quaternions. A displacement corresponds to a multiplication with the according quaternion. This means that any displacement only alters the direction of the three dimensional view on the universe.
Could this model answer further questions or do more severe unanswered questions arise?
Or general steps controlling the "birth" and "death" of a sinkhole conceptually similar to Wilson's cycle in plate tectonics?
Full disclosure: I'm a protein biochemist and a cell biologist. I have no expertize in physics or cosmology.
But I have been mesmerized by documentaries on black holes on science cable channels.
One of many things that I do not understand is the different depiction of massive and super massive black holes.
Since their mass has collapsed into a single point, shouldn't all black holes be the same size in 2D, regardless of their mass?
Why are black holes depicted as a big black planet-like objects with swirling gas around them?
Is it more appropriate to depict them as a drain (like a flushing toilet)?
Reference link: https://en.wikipedia.org/wiki/Dark_energy;
'Concordance Cosmology without Dark energy',
This is a rebuttal to a reviewer's comment about my claim that Absolute Peak Luminosity of type 1A Supernova are proportional to G^(-3) rendering Apparent SN1a distances having a dependence to G^(3/2)
Let me know if you disagree that I kicked this objection to the curb and thus all Supernovae distances are overestimated by G^(3/2) !!!!! :)
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REVIEWER: I’m also skeptical that the luminosity of a SN Ia if G were different would scale as G^-3 (or M_ch^2).
Ni-56 production is not a simple rate-limited process; SNe Ia undergo a deflagration that (in most cases) transitions to a detonation. They burn about half their mass to Ni-56 (depending on when the detonation occurs). Even if Ni-56 production were a simple process, the radius (and thus the density) of the white dwarf also changes with G.
ANSWER: Firstly, let’s consider the reviewer's assertion that density in a White Dwarf also changes with G. That is incorrect. Detailed derivation was contained in appendix and is reproduced below.
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I corrected an assumption about Luminosity and Mass. Now it is perfect...:)
This argument proves that Luminosity depends upon G^(-3) and since G is epoch dependent in my theory and proportional to the inverse of the 4D radius of the Universe, earlier epochs had stronger Gravitation. Stronger Gravitation means weaker SN1a, resulting in overestimation of distances. The farther the SN1a is, the larger the overestimation.
The distances are overestimated by G^(1.5). Once one corrects them, Inflation Theory disappears in a puff... The same goes to General Relativity and Dark Energy....:)
The argument supporting this dependence is based on the work of David Arnett about type II Supernova Luminosity. This is an estimation of the dependence of the Luminosity with G.
To extract the dependence, we force the radius of the Supernova to have a Chandrasekhar radius dependence. We also estimated the M0 (Sun mass) dependence upon G. The Sun mass is a relative mass reference within the context of Supernova mass. Supernovae occurs in the dominant radiative pressure (as opposed to gas pressure) regimen. Under that circumstance, the Luminosity dependence comes up as Luminosity Proportional to G^(-3).
Needless to say, this derivation is trivial and consistent with Supernovae and Star models.
It takes just one page to be derived, easy as Butter. (of course, after David Arnett did all the hard work...:)
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This means that the SN1a ruler, which is the basis of Cosmology and Astrophysics would be faulty under an epoch dependent G context. Since HU is epoch-dependent and predicts the Supernovae distances perfectly and without any parametrization, that places the Standard Model in a very precarious position.
If you add to that, HU observation of Neutronium Acoustic Oscillations or NAO... (which is what Algebraists should be saying right now...:) I think, there is reckoning coming...
See the NAO... SDSS had this data for 10 years. Since they are basically Algebraists and see the Universe according to GR, they cannot imagine acoustic waves along distances. The Universe is supposed to be Uniform...
HU sees oscillations primarily along distances (which corresponds to cosmological angles). There may or may not be cross-talk with the 3D angular modes. I say that because I don't see the 150 Mpc wavelength in HU 2-point correlation.
So, How Long will the Community refrain from welcoming my conclusion that there was no Big Bang (there was Many Bangs) and that the Universe didn't come out of a fiery explosion, dilation is nonsense, vacuum fluctuations driving a Big Bang are utterly nonsense.... GR is nonsense..etc.
Below is the Hypergeometrical Universe Theory (HU) to the question of how environments with different Gravitation would affect the Absolute Luminosity of SN1A Supernovae.
The derivation starts with the work of David Arnett on type II Supernova. We apply type 1A Chandrasekhar radius G dependence to the thermal Energy and to R0. We also scale a Sun Mass by modeling the Sun mass under different regimen - Low and HIgh radiative pressure.
This is an estimation to see if they expected dependence is consistent with astronomical observations, so the precise value is less relevant than the range.
Astronomical observations are consistent, within the logical framework of the Hypergeometrical Universe, with a G^(-3) dependence. That is exactly what one obtains using the High Radiative Regimen to evaluate the mass of the Sun G dependence.
That said, irrespective to which model we useed the range varied Between G^(-3.5) and G^(-3).
The relevance of this results is that in HU, G is inversely proportional to the 4D radius of the Universe.
The Standard Cosmological Model considers that the Absolute Luminosity of a SN1a is constant or standardizable (variations due to different amount of ejecta are renormalizable through the empirical methodology WLR).
HU proposes the G is epoch-dependent, which would make SN1a to be epoch-dependent in a way that farther away SN1a had intrinsically weaker explosions and thus reduced Luminosity. Our adjustment of David Arnett's work indicated a G^(-3) Luminosity dependence.
That would result in an overstimation of the distances of Supernovae by G^(1.5). After correction of the distances we can compare HU d(z) predictions with the astronomical observations. See plot below:
The results below are consistent with
how can I find observational data for circular velocity of spiral galaxies (v(r)) versus the distance from the center of galaxies(r)?
It is not known wether axions where formed before or after the inflationary epoch. It is usually assumed that axions are produced during inflation, during the GUT symmetry breaking phase which are energies of the order of the GeV’s scales (between 10^11-10^16GeV’s).
Nevertheless, there are models which work on the production of axions just at the end of the Big Bang/before inflation, if this were the case the energy scales of axion production could even reach the TeV energy scale. Is this a correct claim?
The symmetry between matter and antimatter is thought to have been broken in the early universe a short time after the end of cosmological inflation (« baryogenesis »). Matter and antimatter annihilated each other except a small excess of baryons and leptons which outnumbered their antiparticles and are at the origin of all the matter content of the universe. This is still at theoretical level (no experimental proof). However the pressure has probably changed very quickly from negative (inflation …) to positive (cloud of baryons and leptons). Also the energy produced by the annihilation must have gone somewhere. Could anybody give a simple digest of what physically occurred during baryogenesis and of the orders of magnitude according to the most accepted model(s) ?
From the deceleration parameter q=−(a¨a/(a˙)2) ---------(1)
where a is the scale factor.
Hubble's parameter H=a˙/a ------------(2)
Substituting equation (2) in (1),
q=−(a¨/Ha˙) ---------------(3)
Making a¨ the subject in equation (3),
a¨= −(qHa˙)
This clearly shows that there is a link between the magnitude of the Hubble's constant and the acceleration value of the Observable Universe.
The present day value of q is approximately −0.55.
Is my proposal correct?
May I have your opinion on the solution of Black Hole Information Paradox proposed in the attached
TEDx talk?
In 1920 Eddington published a book Space, Time & Gravitation on general relativity which included an ingeniously simple derivation of light bending using general relativity. The book may be found at a link below, and the explanation is on page 99. Einstein used essentially the same explanation in The Meaning of Relativity published in 1922 (also linked below), in the vicinity of equation (107). A coordinate transformation is made so that coordinate light speed is isotropic and Huygens bending, also known is the Fresnel principle, is applied. The answer is taken at face value without re-transforming coordinates.
Using a graphical analysis of Huygens bending, I concluded that it is not coordinate independent. See image attached.
Has there been any discussion of this method since 1922? Is it still considered correct?
Hubble’s law doesn`t explain why distant objects were receding fastest. Conversely, a distant observer will see that the distant objects (those nearest to us) are receding fastest than those nearby (those distant to us). What causes such illusion?
A 3-spherical geometry for the Universe was once proposed by Einstein and is still held by others.
For example, a 3-spherical geometry could explain Big Bang evidence, such as:
- The redshift of galaxies. Explained by geometrical lensing from the geodesics of S3.
- The CMB. Could be caused by diffused light from geodesics originating from “behind” earth’s antipode, etc.
I’m sure there is more evidence for the Big Bang, but the two above are the most cited.
The reason I’m considering that particular geometry for the Universe is that the existence of matter-waves can be attributed to S3 motional geometry.
One more thing, the dimensions of the 3-sphere are assumed to be spatial and do not include time as a dimension. The fourth dimension of the hypersphere is unobservable therefore unknown.
If that’s the case, the need for a Big Bang becomes questionable.
Your comments, please.
Bernardo.
As a theoretical cosmologist, spectral index, running spectral index and scalar to tensor ratio are some of the things one can easily calculate for the model we devise. But it comes very handy to plot them on top of the distribution that is usually obtained by running CosmoMC on Planck data. Can someone describe how these plots are obtained and what is quickest way to reproduce the such as fig.9 in the link attached, without divulging oneself into the details of Planck data analysis.
I think that inside a reactor one can obtain neutrons of different energies. My question is if it is possible to create two sources as in the picture?
It has been deduced from WMAP and Planck observations that the expansion of the universe is accelerating. This would mean that the present pressure in the universe is negative. Do we have any knowledge of the value of this pressure or of its order of magnitude (be it obtained by calculation or by measurement) ?
Under what natural processes could stellar formation have occurred after the initial singularity but prior to a cosmic inflation event?
Assume this is the scientific actuality, so it is not a question of if it could have occurred but how it could have occurred.
Assume CR does not indicate any ongoing cosmic expansion.
Thank you,
r
Dear Colleagues,
I send you the paper
I. A. Urusovskii, Multidimensional Treatment of the Expanding Universe,
Physical Science International Journal, 4(8): 1110-1144, 2014,
Containing answers on questions of Dr. Robert Oldershaw (see the Figure 6 in the paper).
Best Regards,
I. A. Urusovskii
Is it possible to have a world that does not change its scale factor a(t)? Physically there is evidence for it, a(t)=Constant ? Is it means a possible world with a constant radius?
Cosmologist
I am interested by some connections between cosmology, gravity etc with life sciences, biophysics or whatever. I will be appreciative if you can give me some initial starting points with articles, textbooks etc dedicated to my interests.
Giant black holes are suspected be located at the center of spiral galaxies.
In our galaxy, it was observed that stars located near the center have elliptical trajectories that correspond to the presence of a mass at the focus of the ellipse.
Does anyone know what are the observational elements requiring that this mass must be a black hole?
Why could not it be, for example, a dense cloud of gas?
Thank you for any element of information.
I noted that ultraluminous X-ray Source (ULX) luminosity is usually determined by calculation from flux and host galaxy's distance measurement. I want to know the idea of determining ULX membership to a particular host galaxy, since there maybe no counterpart observation in other bands.
We have learnt from the big bang cosmology that all the particles was created after the big bang explosion. My question is that whether these particles was created from the energy released due to the big bang? If yes, the energy density must be decreases during the course of expansion as it is continuously converting into masses or matters. Again if it happens so, the mass of universe must be increasing with time or expansion.
Please some give some light on it. I'm working on a solution of Einstein's field equations and I got an expanding solution with an initial singularity. As the time increase to future, its mass and radius increases. So I need to explain the increase in mass with time.
Over the years, many physicists have wondered whether the fundamental constants of nature might have been different when the universe was younger. If so, the evidence ought to be out there in the cosmos where we can see distant things exactly as they were in the past.
One thing that ought to be obvious is whether a number known as the fine structure constant was different. The fine structure constant determines how strongly atoms hold onto their electrons and is an important factor in the frequencies at which atoms absorb light.
If the fine structure were different earlier in the universe, we ought to be able to see the evidence in the way distant gas clouds absorb light on its way here from even more distant objects such as quasars.
That debate pales in comparison to new claims being made about the fine structure constant. In 2010, John Webb at the University of South Wales, one of the leading proponents of the varying constant idea, and a few cobbers said they have new evidence from the Very Large Telescope in Chile that the fine structure constant was different when the universe was younger.
While data from the Keck telescope indicate the fine structure constant was once smaller, the data from the Very Large Telescope indicates the opposite, that the fine structure constant was once larger. That’s significant because Keck looks out into the northern hemisphere, while the VLT looks south.
This means that in one direction, the fine structure constant was once smaller and in exactly the opposite direction, it was once bigger. And here we are in the middle, where the constant as it is (about 1/137.03599…)
So, do you think that fine structure constant varies with direction in space?
For further reading on this issue, see http://www.technologyreview.com/view/420529/fine-structure-constant-varies-with-direction-in-space-says-new-data/.
Refs:
arxiv.org/abs/1008.3907: Evidence For Spatial Variation Of The Fine Structure Constant
arxiv.org/abs/1008.3957: Manifestations Of A Spatial Variation Of Fundamental Constants On Atomic Clocks, Oklo.
Included here you can also find a 2004 ApJ paper by John Bahcall, who is a proponent of varying fine structure constant. (URL: http://www.sns.ias.edu/~jnb/Papers/Preprints/Finestructure/alpha.pdf)
If I'm correct that images of distant stars and galaxies can show multiple celestial objects at massively differing distances away and therefore some points of light are effectively representing images from differing moments in the past.
If those different points of light are actually derived from differing moments in time, how do observers/recorders represent the difference in time between them visually or analytically?
It would rule out vacuum being the source of the CBR
(or confirm)
Flux from any object drops with increase of red shift. As the object is in higher red shift, it looks fainter. But in the sub-millimeter band galaxies get brighter with increase of z. The explanation is given as negative 'k-correction'. Can you explain it?
According to Mukhanov's "Physical foundations of cosmology" (page 230), to solve the Horizon and flatness problems, the rate of change of the scale factor today should be greater than the rate of change at the beginning of inflation. However the attached diagram shows that it's the opposite. Could someone please clarify this issue for me?
Fleury, Dupuy, & Uzan reported in Phys. Lett. (2013), that it is possible to interpret the Hubble diagram in the context of nonhomogeneous universe. They wrote as follows:
"In the standard cosmological framework, the Hubble diagram is interpreted by assuming that the light emitted by standard candles propagates in a spatially homogeneous and isotropic spacetime. However, the light from "point sources"--such as supernovae--probes the Universe on scales where the homogeneity principle is no longer valid. Inhomogeneities are expected to induce a bias and a dispersion of the Hubble diagram. This is investigated by considering a Swiss-cheese cosmological model, which (1) is an exact solution of the Einstein field equations, (2) is strongly inhomogeneous on small scales, but (3) has the same expansion history as a strictly homogeneous and isotropic universe. By simulating Hubble diagrams in such models, we quantify the influence of inhomogeneities on the measurement of the cosmological parameters. Though significant in general, the effects reduce drastically for a universe dominated by the cosmological constant."
So do you think that Swiss-chess model can be made close to observation? What do you think?
The early models of decay can be found in the works of Friedrichs (1948), and Feshbach (1958). In these works it is said that the intra-nucleus dynamics of the particle(s) to be emitted, is influenced and becomes coupled with the dynamics of the same type of particle(s) in the environment, i.e. in the states belonging to the continuum of energies in the environment.
So, in the above works a total Hamiltonian HT is built, comprising the Hamiltonian of the parent nucleus, the Hamiltonian of the continuum, and the coupling Hamiltonian.
Referring for simplicity to the α-decay, HT should comprise the Hamiltonian HB whose eigenstates are bound states of α, the Hamiltonian Henv of the continuum of α-levels of energy of the environment, and a coupling Hamiltonian HC. The effect is said to be a widening of the bound states of α into resonance states, which are no more of a sharp energy but have a width Γ, and therefore have a half-life proportional with ħ/Γ.
I am asking three questions:
A. As the environment is in VACUUM state in the beginning of the decay, what can move in the vacuum s.t. the movement of the α inside the parent nucleus, can get coupled with? What moves in the vacuum?
B. I know that the nuclear decay has some similarity with the de-excitation of an atom, but in atom de-excitation the electron is influenced by an e.m. field. To the difference, in α-decay one cannot say that the α inside the nucleus is influenced by the α outside. We don't know an α-α field. So, which field can couple the intra-nucleus α with the α-vacuum?
Gravitation
Delta\tau_g = \frac{g}{c^2} \sum_{i=1}^{k} (h_i - h_0) \Delta t_i
How the difference between 0m and 5000m on Earth should be today (after for example 4.5 billion years):
\Delta\tau_g = \frac{~10}{9*10^{16}} (5000m - 0m) 4.5*10^9 years = 21.9 hours
Following the theory, shouldn't we see a difference of 21.9 hours between two picture of the sky taken at 0m and 5000m?
The observed Lithium abundance is in disagreement with the standard big bang model. What are the possible solutions to the problem? How much the observations are reliable in this case? Is it possible to exist a method of destruction of Li that we don't considering or it is beyond standard model phenomenon?
Space of Universe is static! Yes or no?
Question: Are there any observations that do not fit into the model static space of Universe, are there any theoretical obstacles to the existence of such a model?
I assume that the Universe is eternal, infinite and static, it is not expanded and not curved, it is possible to construct a preferred inertial frame of reference in which the CMBR is most isotropic. The matter in this space evolves, but the average density of matter and energy (in large enough volumes) fluctuate within a rather broad range.
The light in this model is "tired", the speed of light depends on the optical density intergalactic medium. Gravity is also "tired" t.i. weakens a little faster R2. The energy of destroying matter goes into the surrounding vacuum. The excess energy from the vacuum give rise to new particles of matter.
I state that all the observed cosmological effects can be explained in such a Static Model of the Universe.
See attached "Basic_Cosmological_Formula_1_En.pdf"
Dear colleagues, I do not ask, what are the problems faced by other theories (though I would be interested in your opinion on that. The General theory of relativity is not applicable to the entire space of the Universe).
I am supervising an undergraduate student doing a final year research project in statistics. For her project she would like to look at cosmological parameter estimation using Monte Carlo Markov Chains. One problem is finding relevant data that she could use.
Does anybody know of any freely available data that would be suitable for the above-mentioned project?
Thank you in advance to anyone able to help.
I've asked this question once; want to be more specific now; hope will be luckier this time around. According to the original Gamov-Alpher-Hermann theory, the CMB temperature goes down with time "t" as t^(-2/3). A recent discovery of accelerated expansion of the Universe apparently is changing this. So what is a new dynamics of that temperature?
A glance through our cosmic neck of the woods reveals that matter in the Universe is distributed in a highly structured fashion, why is it so?
Regards,
Bhushan Poojary
I can´t find anything other than the standard expression valid BEFORE recombination which does not depend on the ionization fraction, or expressions for AFTER the precipitous fall in the sound speed after last scattering. Has anyone modelled that "precipitous" fall (in either sound speed or pressure) in detail as a function of the (small and falling) ionisation fraction?
Space expansion is not absolute, it depends on the length unit – using the co-moving length unit, space is invariant. So, how do we know whether is the space that expands or the standard length unit that decreases?
One may thing that if the length unit were varying, physical laws would not hold. However, that is not true! One can define a comoving system of units where space is invariant and physical laws hold, and all constants keep invariant. The problem is as non-trivial as the old question of knowing whether rotates the whole universe or the little Earth, which inspired Galileo.
Furthermore, there is a suspicious resemblance between Big Bang model and Ptolemy model: both have one unknown entity to drag stars around or away (celestial spheres and dark energy), another to explain local motions (epicycles/deferent and dark matter), both are only valid at distance and both consider that the nearby universe is dominated by matter while the distant one by unknown entities.
In my opinion, we have to give a scientific answer to the above question and not be ruled by presumptions, as it happened in the similar geocentric case. I would like very much to know your opinion: do you consider this question important? Do you have an answer to it?
In this article recently published " http://phys.org/news/2015-01-galaxy-confound-view-early-universe.html ".
It is mentioned that, Some researchers in March last year had used a telescope at the South Pole, namely the BICEP2 telescope, which studied a small patch of sky in detail above the South Pole. They discovered primordial gravitational waves. This in scientific circles was a very big deal, on the level of a "big bang" look at the birth of the universe. New Scientist compellingly described it back in March, "showing us what was happening in the first slivers of a second after the big bang."
However, reported Jacob Aron in New Scientist on Friday, "details of a new analysis of their results have leaked, and they seem to reveal that galactic dust is the likely cause of their observations.".
They still have not ruled out inflation theory yet , but what if we are not able to detect it at all, What other alternative theory would replace inflation theory in case if inflation theory is proved wrong.
Regards,
Bhushan Poojary
Does it imply that if the theory did not allow calculating values of the given quantity in reasonable time, then this theoretical quantity would not have a counterpart in physical reality? Particularly, does this imply that the wave functions of the Universe do not correspond to any element of physical reality, inasmuch as they cannot be calculated in any reasonable time? Furthermore, if the ‘computational amendment’ (mentioned in the paper http://arxiv.org/abs/1410.3664v1) to the EPR definition of an element of physical reality is important and physically meaningful, should we then exclude infeasible, i.e., practically useless, solutions from all the equations of physical theories?
The reports by Tifft on quantization of galactic redshift are well-known to astronomers. Read for example http://www.vixra.org/abs/1309.0011. See also a recent review on redshift theories by Marmet at http://www.marmet.org/cosmology/redshift/mechanisms.pdf
Kaluza–Klein theory is theory which uses 5th dimension to unite Gravity with Electromagnetism.
does this theory have any short fall or is it perfect?
If someone can help me with original article it would be nice of them.
Regards,
Bhushan Poojary
Can we get any help of dark energy momentum tensor in f(r,t) theory?
Cosmological interactions are often related to the energy density of the interacting system or to their time derivatives. Is it possible to relate the interaction between spins of a fluid with its energy density? Or with an arbitrary function of its time derivatives?
In other words, can a cosmological interaction be derived from the interaction between spins of a cosmological fluid ?
In a rather old paper, Michael Heller argues that in certain cases it is possible to remove the initial singularity from cosmology models. He discusses b-boubdary and noncommutative geometry. So what do yo think?
The new discovery from the BICEP2 indicated that the inflation may be happened for a longer time than predicted before. In addition to that, the high values of gravitational waves detected indicated that there is a larger force of expansion than thought before. Is this an indication that inflation may have kept happening until the recent discovery and it may be responsible for the detected expansion?
I read somewhere that Einstein's equations may be expressed in terms of Klein-Fock-Gordon equation, but i am not sure yet how to do that.
In a paper, Fiziev and Shirkov discuss solutions of Klein-Fock-Gordon equation and its implications to Einstein's equations. In effect, this may imply that Einstein's equations have wave-type solutions.
What do you think? Your comments are welcome.
As far as I know in order to explain the horizon problem in cosmology, two major theories have been put forward viz, inflation and VSL (varying speed of light). My question is this, by detecting primordial gravity waves by BICEPS 2, thus proving the inflation theory, w