Astrophysics - Science topic

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What is the role of anisotropy in the dynamic modeling of star. For realistic modeling of star what should be the trend of anisotropy from center to boundary.

Some petroleum and geophysics companies use controlled-source seismology for Mineral Inspection and cavity detection. These methods based on impulsive source controllers such as (dynamite, air gun seismic source, etc.). More efficient techniques use a Seismic vibrator for seismic wave generator such as chirp, sine or square seismic waves.

I wonder if recents detections of Gravitational Waves coming from earth or space using optical interferometry, and how to distinguish between each of them, especially when seismic wave have a same chirp form such as Gravitational Waves?

Example of Seismic Source: http://seismicsource.com/html/index.php

If global warming cannot be resolved by controlling/minimising gas emissions, then extraordinary measures may be the only viable options, one of such ideas is placing a solar shield between the sun and earth at the L1 lagrangian point to obtain a reduction in solar insolation . It may sound crazy, more like science fiction to know that a disk of 2000km in diameter would be necessary to reduce solar radiation reaching earth by 1.7%. I wonder about the sort of stresses that would be experienced by such an enormous body. Also, what sort of materials' properties would be required to withstand the conditions at L1, for example solar radiation, other rays. While it is possible to calculate the disk's orbital velocity around the sun, its angular velocity (around its axis) is difficult to calculate. I would be grateful if those with relevant experience could share their thoughts about how such calculations could be achieved.

Hi everyone,

I am studying MSc Astrophysics and my supervisor informed me last year that I would need to know Python to create plots in order to analyse data.

So I had started watching Python videos but when it came to using it for Astrophysics it turned out I still had not learnt anything. Being new to Python I had been 'learning' it in the ways of building a website and not for Astrophysics.

It's not applicable to what I am working on.

Long story short, I have been given some code to work with for analyzing chemical abundances in dwarf galaxies in the MW Galaxy. I feel I am learning by trial and error and ideally I would like to replicate scatter plots that I have seen in research papers but using my own data.

Is it possible to 1.) Know what programming software/language a scientist has used in their paper and 2.) Is it possible to get the code (the structure/layout) more than anything else?

I'm teaching myself Python and whilst everyone says it's easy compared to other programming languages, this is my first and therefore no comparison: just a lot of libraries that do many different things. I am finding it rather frustrating and need a "all you need to know" book on Python for Astropysics.

Equally if anyone knows any helpful resources I would be very grateful. Thank you!

What we actually mean by "Dark Matter Energy" in layman language?

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 was once told that stable isotopes of lighter elements such as H, N C , etc are found in stars, planets, etc. Can anyone suggest any literature which talks about the formation of these isotopes?

Does the New Astronomy Journal charge fees for publishing accepted papers? Are there any page charges?

Or is it totally free like Research in Astronomy and Astrophysics Journal of IOP or Journal of Astrophysics and Astronomy of Springer?

There are some Computational fluid dynamic numerical simulations available like John Hopkins CFD numerical simulations database is available to use. Is that can be used for Astrophysics purposes?

What are the major unsolved theoretic problems on the astrophysical dust molecular clouds and their evolutionary dynamics?

We can direct this question to astrophysics scientists, theologians, philosophers, scientists thought and civilizations! why?

Astronomy shows that the universe is very wide and the distances between the planets are very far away, especially those distances between solar groups or between galaxies. So, for now, humans can not get out of the earth and settle outside.

Nor have we found references in religious beliefs about the possibility of humans coming out of the earth.

As well as philosophy scholars did not deviate from the geographical framework of the Earth!

It was amazing to see the very first image of a black hole. I'm not expert in the field of astrophysics, but in the interest of AI, I think the image is worth to be discussed more. I have made a blog to explain my point of view:

https://scientificpedia.blogspot.com/

Agree? Disagree?

Astrophysical S-factors for thermonuclear reactions that produce electron neutrinos.

Dear Sirs,

I think many knows the ideas due to Jules Henri Poincaré that the physics laws can be formally rewriten as a space-time curvature or as new geometry solely without forces. It is because the physics laws and geometry laws only together are verified in the experiment. So we can arbitrary choose the one of them.

Do you know any works, researchers who realized this idea. I understand that it is just fantasy as it is not proved in the experiment for all forces excepting gravitation.

Do you know works where three Newtons laws are rewritten as just space-time curvature or 5D space curvature or the like without FORCES. Kaluzi-Klein theory is only about electricity.

To publish a Unified Theory of Everything, which includes a series of papers describing and proving its Astrophysics, Electromagnetics & Optics, Gravitation, Weak Force, and Strong Force counterparts, what would be the best Scientific Journal to publish it altogether, or is it better to publish it as a book with chapters covering individual proofs in different physics disciplines? If submitting to a Journal, how can the intellectual rights be protected in the peer-review process? If published in a book, what would be the pros and cons in comparison to being published as an Academic Journal Paper?

Dear Sirs,

I would like to find out more precisely whether the 2nd Newton law is valid or not in wide range of masses, accelerations, forces. Particulary I have a question whether the inertial property of body (inertial mass) is able to stop the body for small external forces or not. I have found in the Internet the fresh articles with tests of the 2nd Newton law for small accelerations (10^-10), small forces (10^-13) and SMALL masses (about 1 kg). The articles deal with the question of dark matter and MOND theory in astrophysics.

But I am interested in BIG masses. Could the test be carried out in planetary scale? Maybe for the Moon or asteroids? Or for masses like 1000 kg? Thank you very much for any references.

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!

the gravitational waves are travels through the universe with the speed of light and it is the disturbances/ ripples in the fabric of space-time. as observe in the electromagnetic radiation light is decays/redshift, similarly in the case of gravitational waves curvature of any massive astrophysical objects affects or deacay it???

Kepler-186f is the first earth-sized planet located in the habitable zone of another star that has been discovered. With this discovery, the search for life on other planets has entered into a new zone of discovery.

This question relates to naturalistic explanations, because they can approach to the reality or retreat from it with time.

A three-dimensional (3-D, nonplanar) geometrical configuration of astrophysical fluids could be conveniently visualized.

What is a justified way to visualize one-dimensional (1-D, planar) geometrical configuration of dust molecular cloud fluids in astrophysics?

What is well represented by the single spatial variable, x, in this context?

The constitutive dust grains in astrophysical environments are partially ionized. What should be the most appropriate (effective) form of dust-dust interaction in astrophysical environments? In a broader sense, how should we improve the existing models in the above light?

Astrophysical fluids are nonthermal in nature. Could you please provide a list (preferably, tabular form) of various nothermal distribution laws for the constitutional particles relevant in large-scale astrophysical fluids?

Can any body name some astrophysical fluid instabilities still lacking theoretical explanation?

Paranomal Research should be considered research, we all understand that, but what kind of research? What branch?

At the dawn, of the 21st century during a reign governed by money and greed the buzz in the economic and technological race was to build an economy based on hydrogen. A couple years later with the financial internet crisis of 2001 all this buzz disappeared and we entered a reign of terror and war governed by a different type of ethics…

Now, we are facing a different challenge: the climate change due to the over consumerism and accumulation of pollution since the 19th century. After decades of foolish hard geo-engineering experiments scientists, engineers and technologists have to come up with all kind of ineffective “solutions” (some are doing worse than good) to master the astronomical forces involved in order to control the effects of climate change and continue business as usual…

Hydrogen is seen as a non-polluting way to store renewable energies and nuclear energy since its recombination with oxygen produce only pure water. It is a transportable fuel for vehicles and other tools and devices running on electricity.

Further, some scientists fascinated by the solar nuclear energy (“illimited source of free energy”) have convinced uneducated deciders that the ultimate goal was to master the nuclear fusion and build an experimental international power plant called ITER.

Please, justify your position by sound arguments.

Thank you in advance for your esteemed expert contributions and for your understanding.

Kind regards.

No personal attacks, insults, pollution of the answers with popular press clippings from other discussion will be accepted.

The derivation of orbital velocity is presumably well understood. One method is to set the centripetal force equal to the gravitational force and solve for v.

Mv^2/r = GMm/r^2

for which orbital velocity becomes v = sqrt(GM/r)

Now let's assume we have a spacecraft in stable orbit around a body at some distance r(1) and want to move the craft to a higher orbit r(2), to do this it must fire it's engines, i.e. accelerate the craft (a) for some time (t), and presumably increase its velocity as ∆v = at, however Newtonian theory tells us that the velocity has indeed decreased as r(2) is larger than r(1).

So I would like to know what kind of Hokus Pokus is normally applied to explain this problem.

For example:

In astrophysics, in the theory of black holes, when it is said that an in-falling body will appear to “freeze” (stop) at an event horizon of a black hole (originally by Oppenheimer & Snyder) there is a misconception: The radiation from such an object will have already fallen far below the visible spectrum of an observer stationed at a safe distance from the horizon, and the quantity of radiation emitted will approach zero as wavelengths approach infinity. What will be seen of a falling object still relatively high above the horizon is a fading and flickering – then nothing. And to be clear, so long as an object is visible, its acceleration will be observed to increase (it is falling in an intense gravitational field!) as its clock and emissions slow.

See my Black Hole Physics.pdf

What are the observational and practical evidences to support the fact that there exist strongly correlated astrophysical fluids in galaxies?

Suggested reading materials are welcome.

This post, written by Thomas Boisson for the group Astrophysics, Astronomy, Quantum Physics on Facebook, summarizes all the major problems of quantum physics, nuclear physics, cosmology, particule physics and astrophysics that are still to be solved.

You can propose your solutions, ideas, for each of the mentioned problems. The goal is to make this discussion a rigorous scientific debate.

Hi All!! I have recently completed my PhD in theoretical astrophysics with work on accretion flow around black holes. Now I want to venture into some observational studies. I would like to know how I can make use of the VIRTUAL OBSERVATORIES to start some good quality research work in observations. I would be very glad if you could share some useful links or documents. Thanking you all...

Astrophysical objects stability in their own state.

Spherical waves are ubiquitous in astrophysical environments. Can someone provide some useful references on spherical wave analysis in spherical gravito-magnetized fluids?

I will be very grateful if anyone can give the examples for both in astrophysical and laboratory perspectives.

I wonder about the source of the formula at internet

http://www.pantheory.org/HF.htm :

[((z+1)²-1) / ((z+1)²+1)] c / H₀

H₀ – Hubble’s constant, c – speed of light.

“Comparing Hubble calculated distances and brightnesses with Pan Theory calculations of distances and brightnesses."

I have checked the formula against 100 galaxies with [0<z<=1]. The correlation was ca. 99%. Somebody knows where the formula stems from? JM

It is well-known that the ground velocity of a plane or helicopter does not depend on relatively fast Earth rotation (~2000 km/h). But a rocket's ground velocity at the high enough altitudes does it increasing if the flying direction is close to the direction of rotation and vice versa.

What is the dependence of such a shifting on altitude?

-Up to now we usually use the classical mathematics the origin of which is at the end of the 19^th century and/or at the beginning of the 20^th century. Even the contemporary quantum physics, astrophysics, and AI of the 21^st century are still using that classical mathematics! In von Neumann's quantum mathematics there is no any anomaly whatsoever in Thomas Kuhn's 'The Structure of Scientific Revolutions': why?

-Thanks for your answers! Marc

Hawking's Legacy

Black hole thermodynamics and the Zeroth Law [1,2].

(a) black hole temperature: T_H = hc³/16π²GkM

The LHS is intensive but the RHS is not intensive; therefore a violation of thermodynamics [1,2].

(b) black hole entropy: S = πkc³A/2hG

The LHS is extensive but the RHS is neither intensive nor extensive; therefore a violation of thermodynamics [1,2].

(c) Black holes do not exist [1-3].

Hawking leaves nothing of value to science.

REFERENCES

[1] Robitaille, P.-M., Hawking Radiation: A Violation of the Zeroth Law of Thermodynamics, American Physical Society (ABSTRACT), March, 2018, http://meetings.aps.org/Meeting/NES18/Session/D01.3

[2] Robitaille, P.-M., Hawking Radiation: A Violation of the Zeroth Law of Thermodynamics, American Physical Society (SLIDE PRESENTATION), March, 2018, http://vixra.org/pdf/1803.0264v1.pdf

[3] Crothers, S.J., A Critical Analysis of LIGO's Recent Detection of Gravitational Waves Caused by Merging Black Holes, Hadronic Journal, n.3, Vol. 39, 2016, pp.271-302, http://vixra.org/pdf/1603.0127v5.pdf

Dear all,

In the framework of a special issue of a French magazine that I am co-directing, I am looking for researchers working on Africa in different research fields, for short interviews about the future of Africa.

Women and African researchers are highly welcomed to apply for a better representativity of genders and countries.

Targeted fields, about Africa only (this list in non exhaustive):

- literature/linguistics

- physics/astrophysics

- terrestrial/marine biology

Thank you for your suggestions and applications,

Julie Morin-Rivat, PhD

This project aims to determine laser frequency on-board a Spacecraft. The Spacecraft will be launched with a Space Qualified Stabilized laser device as a payload. When the Spacecraft goes beyond the ‘Sphere of Gravitational influence’ of the Earth (having approximately a radius of 1,500,000  km), the laser device will be operated remotely, so as to determine its frequency during the later part of its journey.

We would like to get some advice about recommended type/model of a miniaturized/ compact Space Qualified Stabilized laser device that will be a good choice as cost and weight are the limiting factors for a cost-effective Space experiment.

The miniaturized/ compact Space Qualified Stabilized laser device will be like those developed by Prof. Robert L. Byer of Stanford University. What will be the most suitable type/model among those presently available from manufacturers, and that are at present being utilized by Principal investigators (PI) for similar Space experiments.

The recent findings in terrestrial laboratories (viz., the PTB Lab. at Braunschweig, Germany, the European Laboratory for Nonlinear Spectroscopy {LENS}, in Firenze, the Italian standards Lab. in Torino, the NIST Lab. at Boulder, Colorado, USA, and the Quantum Metrology Lab., RIKEN, Japan), indicate that the differences of the frequency shifts of a particular type of clock/ laser between labs are in ~10's of Hz, while the current laser/ clock measurement precisions are in the milliHz domain; whereas, the frequency shifts due to the strong solar gravitational potential are of the order of MHz.

Takano T., et al, (Referenced below) have reported measurements (having precisions in the milliHz domain) of fractional frequency shifts between two laser (87Sr) clocks located at two terrestrial laboratories.

Whereas, the proposed Space experiment can be conducted utilizing any Space Qualified Stabilized laser/ clock having even lower measurement precisions than the ones belonging to milliHz domain.

However, the final choice of chosen model of the Laser device will depend on the availability of such Space Qualified Stabilized laser devices and also on cost considerations.

Why does the emission wavelength directly proportional to its duration?

I would like to change the preference of my research interests. How do I achieve that?

I am interested in astrophysics and astronomy

Dear All,

not only in our university, but almost in all well known to me lectures about Dark Matter, MACHOs (Massive Astrophysical Compact Halo Objects) are rather incidentally discussed while candidates as WIMPs, Axions or Sterile Neutrinos dominate the talks.

Is this - with nowadays knowledge and theoretical assumptions - justified?

With the description of a great abundance of primordial black holes MACHOs do serve a hypothetical answer for almost any questions like rotation curves, radial velocitiy, intermediate black holes, missing-satellite-problem, too-big-to-fail-problem, ...

Of course it is a highly speculative topic. BUT the WIMPs are too (if not even more). So shouldn't we - in accordance with the Principle of Occam's razor - favor MACHOs instead, because they are able to solve a lot of problems at once and at the same time we don't need to extend the Standard Model for introducing them?

Why do WIMPs and particle-like entities dominate? Did i miss a hint (for example some fundamental advantages of this models?). Or is it a general problem ultimately based on ignorance to a great extent?

Thank you

May be, just this problem is the central problem for cosmology and cosmologists.

Suppose there is a spherical mass that is *almost* a black hole. It should be possible to measure the distance from the center of the sphere out to an imaginary spherical surface a long distance R away from the center. If we measured the surface area of that imaginary sphere, would it equal 4*pi*R^2?

I have a follow-up question, based on the answer.

Cosmologist are puzzled by the small value of the cosmological constant. Why don't they accept my non-singular model of the universe based on the back-reaction of quantum fields. 

For example, our sun being at close proximity the separation of photons (separation of colours) is too small to detect, but distant systems such as the recently discovered self-lensing binary system KOI-3278, which was discovered by Ethan Kruse and Eric Agol of Washington University, may provide an opportunity to test QGD’s prediction of gravitational colour separation. By the time the light from such a distant system arrives to Earth, the effect should be magnified so as to make the colour separation measurable using high resolution detectors.

Could this explain the spectral lag observed below:

Would it look like this:

See the section on "bending of light" in the attach document.

hallo,

lets assume, intelligent life on exoplanets is connected with a variety of factors which must be given on this planet:

- right Star Class (e.g. G)

- planet formation

- right rotation speed (to minimize thermal stress on biology)

- planet with magnetic field to protect the planet

- occurance of water (origin: e.g. comets)

- temperature zone, comparable to the earth (e.g. water is liquid...)

- oxygen

- biological cell development

- formation of "higher" living organism

- formation of intelligent organisms

- formation if creative organisms

- lots of others imaginable.

I consider 10 independent factors and each factor has a probability of 10^-3 to occur. Then the result is 1 out of 10^30 planets has human-life.

The visible mass of the universe ia 10^53 kg. The mass of the earth is 6*10^24 kg.  The total visible mass of the universe matches 10^29 times the mass of the earth.

Conclusion: if the entire mass of the Universe would be planets, then statistically another earth would be present (unfortunately there is no mass left over to form suns).

Is this reasonable?

Regards

Lothar

The goal of this question was for e to provide a proof that the Absolute Peak Luminosity of type 1A Supernovae have a G^(-3) dependence.

The argument is correct but it seems to be too complex.

There is a simpler argument that people can understand better.  Just follow these links.

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Supernovae distances are mapped to the Absolute Peak Luminosity of their light profiles. This means the the only two measured values are luminosity at the peak and and 15 days later (to measure width).

Supernova explodes through a nuclear chain reaction:

1) C+C->Mg

2) Mg+O->Ca

3) Ca+O->Ni

4) Ni->Co->Fe 

Luminosity is equal to the number of Ni atoms decay per second or dNidt.

So the peak Luminosity is the Peak dNidt. 

There are TWO considerations that together support my approximation:

a) The detonation process accelerates 2-3 reactions (in comparison with equilibrium rates prior to detonation).

b) The detonation process adds a delay to photon diffusion. The shock wave originated in the core will travel to the surface. When the shock wave arrives at the surface, reaction 1-3 should (in principle) stop. Ejecta (non burned residues) are then eject and the photons resulting from the Ni decay have to diffuse through the thick ejecta cloud.

If you look into the Light/[C]^2 curve, you will realize that is has a small delay with respect to Light curve.  The constraint of having a finite star size forces the maximum absolute peak luminosity to synchronize itself with the maximum peak Magnesium rate dMgdt, which happens at the maximum radius. So, the Physics of a finite star and a shockwave nuclear chemistry process forces the Peak Absolute Luminosity (dNidt) to match the maximum rate of Magnesium formation (dMgdt). Implicit in this conclusion is the idea that the pressure and temperature jump expedites intermediate fusions.

My contention is:

a) Light has to go through a diffusion process while traveling from the core. The motion of the detonation curve might synchronize light and [C]^2

b) The model in the python script contains a parameter associated with the light diffusional process leading to the peak luminosity.

I would love to hear about the chosen rate values (I used arbitrary values that would provide a time profile in the order of the observed ones). I would appreciate if you had better values or a model for rewriting the equations for the nuclear chain reaction.

Since I wrote this, I followed up on my own suggestion and considered the shockwave nuclear chemistry approach. You can download all my scripts at the github below.

The shockwave model considers that the amount of light on a cell along the shockwave is is the integrated light created through its evolution. It is developed as a unidimensional process since the observation (billions of years away from the supernova) can be construed as having only contributions from all the cells along the radial line connecting us to the Supernova.

So, the model is unidimensional. That said, it contains all the physics of a tri-dimensional simple model. All rates are effective rates since during the Supernova explosion nuclear reactions are abundant (one can have tremendous variations on neutron content).

The physics is the following:

a) White Dwarf reaches epoch-dependent Chandrasekhar mass. Compression triggers Carbon detonation A shockwave starts at the center of the White Dwarf

b) That shockwave induces 2C->Mg step. The energy released increases local temperature and drive second and third equation to the formation of Ni.  Ni decay releases photons.

c) Photons follow the shockwave and diffuse to the surface where we can detect them. The shockwave takes tc to reach the Chandrasekhar radius (surface of the White Dwarf).

d) Luminosity comes from the Ni decay from the element of volume plus the aggregate photons traveling with the shockwave. They diffuse to the surface

e) Two diffusion rates are considered. One for light diffusion within the Star and another for diffusion in the ejecta.

# Diffusion process with two rates 0.3 for radiation created before the shockwave

# reaches surface and 0.03 for radiation diffusion across ejecta

kdiff=0.3*(t<tc)-0.03*(t>tc)

f) I considered tc to be 15 days, that is, it takes 15 days for peak luminosity. Changing this value doesn't change the picture.

g) The peak luminosity is matched to the peak Magnesium formation at t=tc or when the shockwave reaches the Star surface.

This means that Physics makes the Absolute Luminosity Peak to be also the peak of Magnesium formation and that takes place at the Star surface.

what are measured Stark broadening parameters for Mn I = 460.53 nm and Fe I 413.46 nm?

I have observed rotation curve data of a galaxy, and I want to know what is the best and simplest mathematical model to find the galactic rotation curve and dynamical mass of such galaxy. 

Your help will be appreciated

Pioneer-V was 5.2 x 10^6 km (or 863Re) on Sun-Earth line on March 31, 1960, when first engulfed by solar plasma, but the peak of the interplanetary magnetic field (IMF) was only measured six hours later, after it was measured by Honolulu station. This study shows the IMF was produced 12.5 RE from the earth, but the question is where the IMF was produced? (Given by one page of section “2.1 Re-Visiting the Historical Experiment” with related Fig.1 at: http://www.exmfpropulsions.com/New_Physics/SpacePhysics/Solar_or_Interplanetary_External_Magnetic_Field.pdf)

The Interplanetary Magnetic Field (IMF) as of solar origin was endorsed mainly due to the final report of the Pioneer V experiment on March 30-31, 1960. After reading point 3 in the poster you can decide for yourself (3. Weak Points in Pioneer-V Results Interpretation).

Hi, dear American cowboys! Has anyone tested the secondary aberration effect (i.e. v^2/c^2) at the conventional group delay model with geodetic VLBI?

Is there a chance for cryo-pycnonuclear reactions to take place in the degenerate core of a white dwarf, affecting this way its stability?

How can answer my kid 5 years old who asked me (who is On/Off the moon night and morning?

Observations of spectral lines of metal, helium and hydrogen in solar flares and prominences show that their profiles contain narrow emission component which corresponds to the very strong magnetic fields (10 ³ - 10 ⁴ G) and very low temperatures, approximately an order of magnitude lower than that outside the regions of strong fields (see. eg. Lozitsky V.G. Advances in Space Research, 2015, 55, 958; Lozitsky V.G. et al., Kinematics and Physics of Celestial Bodies., Suppl., 2000, No 3, 449). Because of the limited spectral resolution of observations, the exact value of the lower limit of temperature and the turbulent velocity remains unknown. And what says about this the theory?

If we imagine the Universe as a 3D space-like surface of curved sphere in 4D space, how big is then the radius of this 4D sphere?

The Visible Universe can be in such a picture imagined as just (3D) circle on the surface of this 4D sphere of said above radius. Its diameter is assess on: "An approximate diameter (in metres) of the visible universe (93 billion light years): 8.8 × 10^26." http://www.physicsoftheuniverse.com/numbers.html

despite of the fact that it accounts ca. 14 billion years...  All that due to rapid expansion of this 4D sphere. Are there any guesses on this sphere radius?

If spacetime is like a liquid—a concept some physicists say could help resolve a confounding disagreement between two dominant theories in physics—it must be a very special liquid indeed. A recent study compared astrophysical observations with predictions based on the notion of fluid spacetime, and found the idea only works if spacetime is incredibly smooth and freely flowing—in other words, a superfluid.

If it is true that spacetime is a superfluid and that photons of different energies travel at different speeds or dissipate over time, that means relativity does not hold in all situations. One of the main tenets of relativity, the Lorentz invariance, states that the speed of light is unchanging, regardless of an observer’s frame of reference. “The possibility that spacetime as we know it emerges from something that violates relativity is a fairly radical one,” Jacobson says. It does, however, clear a potential pathway toward rectifying some of the problems that arise when trying to combine relativity and quantum mechanics. “Violating relativity would open up the possibility of eliminating infinite quantities that arise in present theory and which seem to some unlikely to be physically correct.”

If spacetime is a superfluid, then what is the role of gravitons?

In my opinion, x-ray photometry works but I'm looking for the best method and other methods. 

There are several material which light in weight and transparent also they won't allow cosmic radiation to penetrate to it. I'm looking for that kind of material.

Hubble's law says that the universe expands.

But the fact that we see other galaxies moving away from us does not imply that we are the center of the universe. In any point of it the picture will be quite similar: The galaxies will have radial velocity of ca.70 km/s/Mpc or 20 km/s/Mly. It does mean that at the distance of 15 Milliard light years (15 Billion in the American system) they reach the speed of light and still will be accelerated with a distance. The latter means also that they will vanish behind the events horizon and, nota bene, their true relative velocities with respect to us will be greater than c.

When it happens many people think that they vanish from our space without a trace, just as ships vanish after curved horizon of a sea.

Let us consider this more closely:

Let us take 0<epsilon<D, where D critical distance in light years (from Solar System) of such "tranzition" behind the events horizon.

In the moment just before "tranzition", at a distance (D - epsilon), they emit light which arrives to us after (D - epsilon) light years.

But after that critical moment of "tranzition", at a distance (D+epsilon), they still emit light (each star emits the same amount of energy as before in a continuous manner).

That light approach us 2epsilon years latter.

Epsilon may be any number of years.

This could mean the following conclusion: We can see  the distant galaxies, even those of them which just "vanished" after the events horizon with velocity c. Moreover, each year we could see more (and not less) of them.

According to Darwinian Evolution it is accepted that all life on earth has derived from a single source of DNA from which all life has evolved. If extra-terrestrial life has a completely separate source, and unimaginably different attributes, would we be able recognize it as life if we found it.

Dr Carol Cleland from NASA's Astrobiology Institute has pointed out that all 'life on Earth has a common origin,' and all 'terrestrial life represents only a single case'. (Astrobiology Magazine Staffwriter, 2003)

Professor Gerald F. Joyce is widely reported as having formulated NASA's working definition of life, and has stated the definition depends upon life being 'maintained by Darwinian evolution.' However, he has also suggested there may be 'another way,' and that it 'would be a huge breakthrough, if there was some paradigm other than Darwinian evolution that gets you what Darwinian evolution gets you.' (Leslie, 2013)

References:

Astrobiology Magazine Staffwriter (2003) ‘Life’s Working Definition: Does it Work’, Astrobiology Magazine. Available at: http://www.astrobio.net/news-exclusive/lifes-working-definition/ (Accessed: 13 July 2016).

Leslie, M. (2013) Forming a Definition for Life : Interview with Gerald Joyce, Astrobiology Magazine. Available at: http://www.astrobio.net/interview/forming-a-definition-for-life-interview-with-gerald-joyce/ (Accessed: 23 March 2016).

There is a chance that since the moon's gravity is strongest at that point this will minimize the orbital decay. The satellite could also be placed to periodically pass through the high tide to reduce on orbital decay.

Can my idea work?

When considering general relativity and special relativity, the time for an observer dilates when falling into a black hole. The closer the observer reaches the event horizon, the times dilates more. This means that 1 hour for the observer will be 100000000 years for a person on earth. This should continue and beyond the event horizon, the observer should see the universe without the phenomenon called time (the phenomenon that prevents different events from happening at once). This means that, for an observer living inside the black hole, the universe doesn't have any beginning or end. Every event in the universe happened simultaneously. The big bang and the possible big crunch occured simultaneously. Aren't me right?

This question is directed to observational astrophysicists. I am working on the radiation problem associated with massive star formation. I want to know if the opacity of the gas in molecular does vary with distance from the center of a molecular clouds. I see that in the literature this opacity is assumed to be a constant taking a value of about 20 m^2/kg. I will be happy to get an answer from you!

See attachment!

It was suggested many years ago by Jacob Bekenstein that the rotation parameter of a black hole should be quantized as in usual quantum mechanics: J=n * hbar.

Assume that the inner event horizon r_ = m - Sqrt[m^2-a^2] is greater than the Ring singularity radius a. That is, a^2 < (m - Sqrt[m^2-a^2])^2 which for positive mass leads to imaginary a. We therefore must have the event horizon inside the Ring, and a < m or J < m^2. 

Note that if we further consider the inner ergosphere radius with respect to the Ring and upon demanding cos^2[theta] positive definite we get at the boundary a restriction on the angular momentum: J = m Sqrt[2m-cos^2]

This defines a band for J and M : m Sqrt[2m-1] < J < m Sqrt[2m].

See attached plot 

The energy-momentum tensor of a black hole, or what curves the Schwarzschild geometry?

H Balasin and H Nachbagauer

Using distributional techniques we calculate the energy-momentum tensor of the Schwarzschild geometry. It turns out to be a well defined tensor distribution concentrated on the r=0 region which is usually excluded from spacetime. This provides a physical interpretation for the curvature of this geometry.

Red planet: blue sunset

Blue planet: red sunset

Rayleigh scattering, Mie scattering or other effects, which one is dominant effect?

Some astrophysicians say that gravitational waves (GW) were created during the inflation phase of the universe, when the universe was 10-36 second old and expanded billions of billions of billions times. 

I understand this phenomenon was really explosive and created very violent effects, maybe including GW, but thinking that the GW would then propagate somewhere else would suppose that there was a "somewhere". But the universe just expanded, increased in size, but did not grow inside something else. So these GW had nothing to propagate in, and could not reach us now.

Furthermore, if the GW propagate at the speed of light in vacuum, they should be far away from us because our speed is much less that theirs. The only GW we can catch from earth should have been created much earlier than the inflation.

Is this correct?

If yes, one could then infer that the GW were the source of the inflation mechanism and somehow pushed the limits of the universe to make it grow.

Can anyone explain this? Thank you.

I wanna fill the missing values in the radiation belt electron flux, but i am stucked by which method I should adapt. So can anyone give me some advice? I tried the Singular Spectrum Analysis method, but the window length parameter M and the grouping factor K are diffcult to set. How to determine the optimal parameters then?

In the source frame, the initial black hole masses are 36M and 29M, and the final black hole mass is 62M,with 3M radiated in gravitational wave.

There was no EMF, Electron, Positron, Neutrino and Hardrons ejected at old and new emerging Radial Poles?

Astro and Geophyscists

The 'standard model' of theoretical physics says the basic forces are transmitted between bodies and detectors by particles or fields, as speeds up to the velocity of light.  The LIGO gravitational signal is found to be of short duration (light crossing time of the emitter, perhaps) and very close to light speed. .Very likely to be waves on the gravitational field (Einstein) but could still be 'gravitons'. Black holes can't emit light waves, likewise they can't emit gravity waves and cannot exert gravitational force on matter outside.  So how do the proponents explain two black holes pulling on each other, orbiting in the gradually closing binary system?

and

How do we reconcile these two results?

Quasars are believed to be objects ejected from the centers of the Galaxies (or Black holes). Do all of them blow outwards in opposite direction to us in order to agree all of them with such high redshifts ? Note that the motion of galaxies is random! While, even no one Quasar exhibits a blueshift !. Moreover, according to their high redshift all of the Quasars are very distant away. But the universe is isotropic, so our position is not preferred. Hence why we didn`t obsreve any Quasar nearby? According to the isotropy, a distant observer should  observe the Quasars very distant with respect to him, that is they should be nearby to us!. Contradiction. According to Hubble`s law, if the object is bright then its near by and the distant objects are faint. The Quasars are very bright, why shouldn`t they nearby? Why we just accept one part from Hubble`s law, that is: the high redshift of the Quasar indicates that its distant and ignored the other part, that is: the brightness of the Quasar indicates they are nearby?!!1. Finally, Why our Galaxy and many other nearby Galaxies didn`t eject Quasars from their centers? Why this jop is exclusive for distant Galaxies? Because our Galaxy and many other nearby Galaxies are inactive, said astronomers. Why they are the inactiv among the active distant Galaxies? False justificatioin.It is clear such Paradigm is not satisfactory and insufficient, it depends on many unjustified reasons , many contradictions and inconsistent. The paradigm must be reconsidered and readjusted

I am interested in parametric resonance. An introduction to this phenomenon can be found in Landau's book on classical mechanics. Can anyone point out some good reviews on the phenomenon beyond the textbook level? I am looking for some applications of this phenomenon in astrophysical systems. Any suggestions in this direction are welcome

Estimate the ratio between the temperature scale height h = T(dT/dr)^-1 and the mean free path of a hydrogen atom in the atmosphere of a star. Is local thermodynamic equilibrium a valid assumption in the stellar atmosphere? Where does it break down?

A massive O star has a typical luminosity of 3 x 10³⁹ ergs s^-1, a lifetime of 3 x 10⁶ yr, a stellar-wind velocity of 5000 km s^-1, and a mass- loss rate of 10^-5 M_s yr^-1. When it ends up as a supernova, ~5 M_s is ejected with a velocity of 5000 km s^-1. How can estimate the contribution of these processes to the energy and the momentum of the ISM?

I am specifically looking for mass distribution and observed angular velocity of as many galaxies as possible.

(I already solved the problem by setting the keyboard to US English, I explain a message below)

I'm trying to use SpekCalc to simulate a X ray tube, but apprently it's not showing the bremsstrahlung radiation. I´m using a peak energy of 100keV, a theta of 16 degrees, and 5 milimeters of aluminium. But I obtain the same results whatever I have tried. I'm runing release 1.1 light for macOS, and I obtained the same results for windows.

Note: I'm using the values Nf=2 and p=1, instead of those  suggested by Poludniowski because apparently the GUI is not accepting any value minor than 1.0. I have been trying other values with similar results.

Is it proven? In other words, Why stars are round?

Cosmic Microwave Background Radiation (CMB). (question  edit  March 29, 2016)

Assume very dense proto-stellar formation prior to a cosmic inflation event as hypothesized in The Pearlman SPIRAL cosmological redshift hypothesis and no ongoing cosmic expansion subsequent to that cosmic inflation event.

Could the cause of the CMB be from:

Prior to the stellar formation?

During stellar formation?

Post stellar formation?

Prior to that cosmic inflation event?

during that event?

at the very end of that event?

Under The Standard Cosmology Model (SCM) the current distance to the most distant visible galaxies is 46.5 B LY. Is that understanding correct?

CMB-LEAK:

A sub-hypothesize in SPIRAL is the CMB should 'leak' have dissipated 1 LY per year radius beyond the most distant galaxy.

If valid under SCM the CMB is spread out over an area of a sphere with a radius of at least 59.99 B LY = 46.5B + 13.4B is this already established or a published hypothesis?

If CMB does not 'leak' / spread beyond the most distant stars at 1 LY per year why not?

.

Thank you in advance for any and all proposed solutions you can think of. r

Can we speak of a slight linear increase of the core density of sun-like stars during their stay in the main sequence ? As this is a period where gravitational effects are steadily balanced by the radiative pressure resulting from the progressive conversion of H into He. And the same with a bigger slope for the further period of conversion of He into C ?   

Suppose the object belongs to high-soft regime as well as mechanically powerful (cavities, shock) and also has bright nucleus what does it indicate?

Is the anisotropic pressure can destroy the spherical symmetry of

the space-time? Can we use Anisotropic pressure for a spherically symmetric star?

D. Harvey et al. made a study of 30 cluster collisions, with 72 substructures, whereof a spectacular and symmetric case is the Bullet Cluster.

However, this information is biased since the beginning, because in the paper, D. Harvey et al. uses the word "dark matter" as if it were a well-established fact, and didn't thorougly analyse all the possibilities.

One can't even find "dark matter" nearby in the Milky Way. So, my guess is that if one pretends 'finding' it at 3.7 billion light years away, it is a presumptuous allegation and a dangerous precedent.

The data is found from three sources: gravitational bending (blue), X-rays (pink) and visible stars (yellow).

Is it possible to look at the phenomenon in a non-biased way and find other options?