Science topics: Space ScienceAstrophysics
Science topic
Astrophysics - Science topic
Astrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties of celestial objects, as well as their interactions and behavior.
Questions related to Astrophysics
The available source https://ingenieria.uatx.mx/orionfrg/cry/ currently doesn't have the dataset. The existing artIcles also mentioned the link. However, unable to find the dataset.
How would we go about specifying the position of our solar system in the universe, let us say
to an intelligence residing in an unknown part of the universe (assuming for simplicity that we can neglect the sun's motion in our galaxy).
Are there any objects or "landmarks" in the universe that could be used as known points of reference that could be used to specify our location to other intelligent beings residing in a distant part of the universe ? I am thinking of an exact analogue of longitude and latitude for the earth's surface.
An obvious answer would be simply to specify the aspect of the sky (and all known data) as seen from earth or the sun. But would this really be helpful, even if this did specify uniquely our position ?
Relativistic considerations further complicate matters.
Dear All;
If we look closely to scientific works, interviews and speeches of Stephen Hawking, we may see many points unacceptable to norms of science. I myself have identified questionable statements by him that may need to be clarified. I share you several examples:
1- As far as I have seen and read his books, I did not find any referencing styles, bibliography...
2- Strange Statements, for example about Black Holes, rejecting other sciences such as Philosophy,
3- Changing his views constantly, with no reference, talking about Big Crunch, then reject it, talking about Big Bang and then reject it.
4- Advertising "The theory of everything" and then giving it up silently...
5- Did not talk about opposite ideas by others, eg, those who don't accept Big Bang...
6- Changing his ideas about our fate constantly, for example saying we have 1000 years time to leave earth, 600 years, 200 years, 100 years...
7- The reasons he talks about for leaving the earth (such as possible nuclear wars, Viruses, climate change, ... ) could be easily challenged, as humans (if ever according to him ) leave the Earth, wont take with themselves their behavior, culture, tools, systems, policies, attitudes, understanding ideology, beliefs, systems, doctrines? just to name a few.
8- Alien invasion
9- other issues... we talk about later
- I think we as scientists, have to work in accepted norms and frameworks of science and academic research. I partially have spoken about those norms in other discussions, you might like to have a look at... for example:
- https://www.researchgate.net/post/If_the_Universe_is_Infinite_Eternal_and_Ever-Changing_as_Dialectics_since_Epicurus_insists_how_can_JWST_find_its_Limit/2
- https://www.researchgate.net/post/Cosmology_Do_we_still_need_experiments
Please share your ideas on points mentioned above, or other points you know
Thank you
In reference to the attached document, it seems that scientist with the helping hand of metaphysics have created several scientific versions of Turtle All the Way Down viewpoint.
The article criticizes two widely accepted models for the genesis of the universe which can be listed under two hypotheses:
- Nothing
- Something
Both theories have been discussed in enough detail, but this question/discussion is related to the second theory.
I need some guidance to understand and properly use MESA.
My ultimate goal is to modify it such that I can use a variable G.
I saw a video using it to predict the evolution of a main-sequence star. I don't quite understand how it is used to predict observations (Stellar Population).
I am familiar with the Kennicutt-Schmidt Law, relating the rate of galaxy formation and gas surface density
The Tolman surface brightness test (surface brightness versus z), might be used together with wavelength information to determine star population as a function of z.
Then there is the initial mass function
It is not clear how this initial mass function would be changed in an epoch-dependent G.
IN SUMMARY
This is a very early stage of exploration of the issue of Stellar Population Modeling, Star Evolution under MESA.
Advice and comments are welcomed.
I agree that Astrophysics is a multidisciplinary field and that students of Astrophysics are taught many subjects from diverse fields. For example Astrophysics curriculum covers mathematics, relativity, statistical mechanics, quantum mechanics, fluid mechanics, thermodynamics, radiation, lasers, electronics, optics etc. etc. But I am perplexed to find that neither Astrophysics text books nor the study curriculum of Astrophysicists cover theory of elasticity in general or working out stresses and strains in solid bodies in particular.
An obvious answer of most learned readers may be that Astrophysicists are not required to deal with solid bodies throughout their career and hence are not required to study theory of elasticity or to learn working out stresses and strains in solid bodies.
Actually however, the situation is other way around. Since Astrophysicists do not study theory of elasticity and do not know how to work out stresses and strains in very large spherical solid bodies under self-gravitation, they erroneously make them collapse under self-gravitation into black holes, thereby misleading the whole scientific community.
None of the current models of stellar core collapse make any attempt to compute the magnitude of STRESSES in the SOLID iron cores actually produced in massive stars at the end of their fusion burning stage.
As per current models when a solid iron core becomes degenerate, the degenerate electrons get freed from their parent iron atoms leaving behind 'positive ions' of iron. When the positive ions start falling towards the center of the core under gravity, the high energy degenerate electrons are SUPPOSED to push these ions outwards by their degeneracy pressure to counter the effect of gravity. However, to impart an outward push to the falling ions, the high energy degenerate electrons will have to exchange their momentum with the falling ions through elastic collisions. But the high energy electrons cannot exchange their momentum with positive ions through elastic collisions because of their electrostatic interactions and hence can never provide the so-called electron degeneracy pressure in stellar cores to counter the effect of gravity.
The main reason for ASSUMING the electron degeneracy pressure in solid iron stellar cores is the implied belief that a cooled down stellar core cannot maintain its Hydrostatic equilibrium in the absence of adequate thermal pressure and that nothing else can stop the gravitational collapse of such cores. Therefore, the constituents of a solid stellar core are first ASSUMED to be non-interacting for applying Hydrostatic equilibrium equations and then the electrons and ions are again ASSUMED to be non-interacting for invoking the electron degeneracy pressure to support the pull of gravity.
Hence, it turns out that all stellar cores which are said to be degenerate, where some sort of degeneracy pressure is invoked to prevent their gravitational collapse under Hydrostatic equilibrium conditions, are in fact SOLID stellar cores which acquire their stability through Equilibrium equations of elasticity. In current models, the stresses in a solid iron stellar core are never analyzed as a SOLID body under self-gravitation, by using the Equilibrium equations of elasticity. By taking into account the electromagnetic interactions among electrons, protons and ions we can show that the high density stellar cores transform into gravity induced solid state which can support the gravitational loading through development of radial and hoop stresses.
The offended paper is here:
This is a rhetorical question since, in my mind, that is utterly non-acceptable.
I say that while accepting the reality that it takes time to write a few paragraphs in a rejection letter.
That said, it might take years to polish the arguments contained in a paper.
In my case, it took 16 years.
My issue is that, on purpose, I chose to tackle the Big Bang Theory first. It is the weakest model in the whole Physics. There are "Crisis in Cosmology" articles written by everyone and their cats. There is Hubble Tension, S8 tension... Missing Dark Matter, Early Galaxy Formation Conundrum...
Not to mention the lack of any evidence of a False Vacuum, Inflaton Field or Inflaton Particle, etc, etc.
My theory starts with a new model for matter, where matter is made of shapeshifting deformations of the metric (so, it is not Mass Deforms Metric, but modulated metric is mass).
It cannot be simpler. It allows the Universe to have just space, deformed space and time - the simplest possible model.
Occam's Razor will tell you that this model should be part of the conversation.
The Universe starts from a Heisenberg-Dictated Metric Hyperspherical Fluctuation, which after partial recombination is left with an Inner Dilation Layer (IDL) and the Outermost Contraction Layer (OCL).
As one would expect OCL breaks apart when it starts to move, pushed by the IDL. This process has a physical analogy in the Prince Rupert Drop
SO, the model is disappointly simple. No metrics, nothing for you to polish... just a simple model that explains EVERYTHING.
It also debunks General Relativity (Einstein's equations do not describe the Universe expansion). And replicates all Einstein's successes, while providing simpler explanations (instead of time dilation, we have the weakening of forces with absolute velocity).
What about ABSOLUTE VELOCITY? Well, we all know we can define absolute velocity using the CMB. Period. So, absolute velocity (and the breakdown of Relativity) shouldn't be a surprise.
So, my theory also challenges the current Cosmic Distance Ladder and in doing so (using an epoch-dependent law of Gravitation), it parameterless predicts the distances using just the redshifts. The predictions are attached.
So, in doing so, it attacks Dark Matter and Dark Energy and all the sordid interests behind them. I say sordid in the sense that I believe that all these entrenched interests are at play in this summary rejection of my work.
Why would I say that? There is a simple reason. If an editor (and all the other editors) don't bother to justify their actions, one is left with nothing to do other than speculate on the WHY.
Why is it ok for preprint repositories to block my already published work?? That is happening (and happened during the last 16 years) at the Los Alamos Archives.
Why would it be ethical for an editor not to write a single paragraph pointing to an specific scientific reason for yanking a paper out of the review process?
How calous these people can be with respect to Science and Mankind's Future? Science is the key to the Future. It shouldn't be at the mercy of unconfessable motivations.
Recent numerical simulations show that the inner part of the disk seems to oscillate in presence of a Large scale magnetic field or when the disk is in MAD state. So, can we correlate this sort of behaviour with the variability of the source?
I would like to publish my Scientific Preprint Paper free-of-charge in an international Astrophysics journal with a satisfactory Impact Factor. Can you please suggest such a journal?
I have published my Research Results on a New Orbital Model for Moving Bodies in the Universe that I am asserting as a result of my scientific analysis, which can be found below:
"Everything Is A Circle: A New Model For Orbits Of Bodies In The Universe"
(Paperback Book) https://www.amazon.com/gp/product/B08NYG14X8
(Kindle eBook) https://www.amazon.com/gp/product/B08PVS2FBW
I will be presenting this work to the general scientific community at #COSPAR in Sydney, Australia, which will be broadcast Live according to Congress schedule on February 2, 2021
and will be available as Video-On-Demand in more detail.
To provide an introductory idea for readers and scientific community in general, here is a short video giving an overview description of the main and most significant findings:
We all know that accretion disks around BHs are presumably be magnetized in nature. If we consider ideal MHD, we know magnetic fields are frozen within the plasmas. Now, magnetic fields are turbulent, so can they help in raising the temperature of the disk? And is it significant?
Dear Researchers in the field :
Does anyone know what the KAGRA Gravitational Waves Observatory it's been up to ?
KAGRA announced at the end of last year (2019) that they were ready for the kick off. And that in February this year (2020) they were turn to the sky for the first (real) observations and be ready to joing the efforts of the LIGO-Virgo collaboration.
But I haven't hear anything about KAGRA since that time.
I'm sure they had to close due to the COVID-19 pandemic, probably since March.
But, now in December, almost the end of the year, I would have expected to hear news about Observatory.
Does anyone know what is it status nowadays ? Maybe the explanation is that the facilities kept shut down almost the whole year since the pandemic.
If someone know fresh news, I'll appreciate the sharing.
Best Regards all ! :)
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.
I want to create preprint of a research article via arXiv. Do you recommend any specific latex template?
I conducted a experiment whose conclusions were opposite as that of Big Bang. So, based on the conclusions of my experiment I concluded that some points in Big Bang Theory are wrong...
The existence of turbulence in astrophysical fluids has been living as a well-known unsolved problem for a couple of decades. The range transitions among three distinct scales of the micro-fluidic kinetics are still lying obscure. In this context, is there any equation of state to describe turbulent fluid media in the fabric of the modified (by turbulence) macroscopic Navier-Stokes equation?
There are several papers which are using following formula (as shown in the picture) to calculate the dust mass (Md) of the dusty environments such as Nebula, loops etc in the ISM. The expression for dust mass shows that it depends on grain size, grain density and grain emissivity, here, for IRAS Survey, grain size = 0.1 micron, density = 1000 kg/m3 and emissivity = 0.0010 for 100 micron, respectively, are used. Are these constants same for AKARI and WISE survey too? OR, are there any other methods for the dust mass calculation using AKARI and WISE data? I would be very much happy to get your valuable suggestions. Thank you :)
Dr. Hans-Otto Carmesin is a prolific theoretician who wrote among other things, these two books:
Modeling SN1a data:
Data H0_20210424.pdf
That said, he leads a field where a lot of unsupported claims are tossed around without anything to support it. That is why they are unsupported..:)
As Dr. Carmesin professed, scientists should follow the teachings of Aristotle and always use the simplest possible model that is consistent with Reality.
Dr. Carmesin's model has nonlocality, dimensional transitions, the usual suspects (Dark Matter and Dark Energy), and an epoch-dependent Dark Energy (figure 8.15 on the first book above).
It is a fantastic work and from my point of view, unnecessary and incorrect.
Unnecessary because there is HU which is capable to explain everything Dr. Carmesin explained without the need for a Big Bang, Dark Energy, Dark Matter, epoch-dependent Dark Matter, Polychromatic Vacuum. Because of that, Aristotle and Occam's Razor would support HU and rebut Dr. Carmesin's work.
Attached is my summary of the problems I found on Dr. Carmesin's claims that SN1a distances support his work.
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This is an ongoing discussion.
Dr. Carmesin provided a reply to my objections and confirmed that he is not sure if his model can predict the SN1a distances.
In fact, he said: "My theory does not fail to predict these distances. I just did not calculate these distances yet for a good reason: I tested my full theory by calculating the measured Hubble constants of the Hubble tension."
First, that is not a good reason. Second, I calculated the distances according to his model and the model failed. See the plot and the attached python script.
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My plot of his model showcases that the model fails to predict the observed distances.
I also drive home the fact that Dr. Carmesin's model modifies the meaning of H0 (the Hubble Constant). Because of that comparison of results are not straightforward and seems to not have been considered before.
The plots also show that HU model predicts the observed distances without any parameters.
This is to understand how the concepts of statistical mechanics is applied in astrophysics.
A Cosmology based on a Chaos-borne Hubble Law
Otto E. Rossler
Division of Theoretical Chemistry, University of Tubingen, Auf der Morgenstelle 8, 72076 Tübingen, F.R.G.
Abstract
A recent classical-mechanical finding, Fermi deceleration, implies a classical Hubble-like law. While its exact size is still open, it is bound to co-determine empirical reality. Some old and new questions concerning the size and the age of the cosmos arise. The current enigma of early old galaxies supports the prediction of a potentially much larger and older cosmos. So does Riccardo Giacconi's finding of ultra-high-redshift x-ray point sources.
(October 8, 2004)
Recently, a classical-mechanics based Hubble-like law was described [1,2]: Light rays
negotiating galactic clusters that are in random motion with up to 1 percent the speed of light (as is realistic) suffer a distance-proportional redshift through "Fermi deceleration." The latter phenomenon was discovered by Loskutov et al. [3] on a chaotic billiard: A fast-moving, low-mass billiard that is subject to random grazing-type collisions with slowly moving highmass boundaries suffers a distance-proportional loss of momentum called Fermi deceleration [3]. The repelling grazing-type boundaries of Loskutov et al. can be replaced by attracting high-mass point centers - with the same grazing-type interactional effect. The slow attracting centers may be galaxies or clusters of galaxies and the billiard may be a light ray. The size of the effect depends on the density, mass and speed of the attracting centers.
The size of the effect appears to be neither too large nor too small to accomodate the empirical Hubble law [1]. If this preliminary result is taken as a cue, the implied lack of cosmic expansion re-opens the age-old question of the size of the cosmos. Fortunately, perhaps, a general-relativistic size limitation remains in charge if the mass density in the cosmos is uniform. In this case, not too much is changed compared to the standard paradigm: The cosmos can still be a pulsatile cosmos, for example, albeit so on a longer time scale.
If the assumption of a uniform mass density is dropped, on the other hand, the general
relativistic bound is no longer finite. This stationary solution to the original Einstein equations was discovered by Benoit Mandelbrot [4], a fact which is not very well known. If the fractal dimensionality of the mass distribution is assumed to be unity (so that twice as large a radius contains not eight times but only twice as much mass - as in an ultra-light hole ridden Swiss cheese), the Schwarzschild radius which limits the size of the cosmos becomes infinite. For twice as much mass by definition has twice-as-large a Schwarzschild radius (and so on), so that no finite limit is reached in the present case. An exactly 1-D Mandelbrot cosmos is both stationary and unbounded. Peebles almost immediately found that the empirical fractal dimensionality of galaxies is about 1.2 up to large distances [5]. This and subsequent data can be re-evaluated by dropping the original assumption of a progressive lack of volume as the remaining distance to the primordial fireball shrinks toward zero. The validity of Peebles' near-unity result will thereby be extended to covering the greater part of the visible universe.
If this prediction is correct, a "Brunian cosmos" (in honor of Giordano Bruno) of potentially unbounded extension in both space and time becomes an option again- But would not the other "pillars of the big bang" automatically preclude so far-reaching a conclusion? Surprisingly, this is not the case. The cosmic background radiation -- the strongest ally -- would assume the role of "mean cosmic temperature" in the sense of Assis [6]. The also observed large-scale fluctuations in the WMAP would reflect a giant honeycomb structure that lies beyond the range of current telescopes (although some infrared and x-ray sources may already be pointing the way). The three other major pillars - primordial nucleosynthesis, inflation and accelerated expansion - would have to wait in line until the gross features have been straightened out. The third (large-distance dimming) may, by the way, prove reducible to Peebles' little-known (1+z)--4 formula [7], cf. [8].
But how about the riddles newly imported by a modern Brunian cosmos? First, in the absence of a far-from-equilibrium big bang, the persistent far-from-equilibrium state of the observable universe becomes incomprehensible. A gravitational effect partially anticipated by Einstein in 1912 [9] may possibly solve the mystery: Any particle in rectilinear motion inside a Newtonian (or Einsteinian) void enjoys a forward acceleration [10], cf. [11]. If this is so, gravitational energy gets "recycled" into kinetic energy in a Carnot-like manner. The same mechanism, by the way, could explain - jointly with Hawking radiation [12] - the second major new riddle that arises: the empirical "non-devouredness" of almost all matter by age-old black holes.
The main asset of a classical explanation of cosmological redshift, when held against the backdrop of the standard model, seems to lie in the fact that it introduces no hypotheses. lt only uses facts that are implicit in classical (post-Newtonian) mechanics and special and general relativity anyhow. lts predictions are irrefutable once their size has been correctly determined. What is surprising is only how many accepted hypotheses suddenly lose their hard-won plausibility.
Nevertheless it would be nice to have direct evidence as well. Very faint distant x-ray point sources appear to possess redshifts in excess of 30. This is because, on the one hand, the sensitivity ofx-ray telescopes is presently 1000 times greater than that of light telescopes [13]
- so that they can look 30 times (squareroot of 1000) deeper into space in principle - and, on the other, x-ray point sources continue to pop up at the lowest brightnesses [13]. This empirically suggested, two-tiered conclusion is incompatible with the big bang scenario (which leaves no room for redshifts beyond about 10 for massive objects). lt is about tobe decided by direct redshi:ft measurements in progress [13]. A hard - if weaker - fact is the recent optical discovery of strongly redshifted old galaxies 12 billion light years away, which has put cosmology into a full-fledged crisis [14,15]. While almost any way out appears acceptable at the time being, the above explanatory scenario was arrived at independently.
To conclude, the classical-mechanical finding of Fermi deceleration has upset the decades old belief that only a relativistic mechanism can account for the Rubble law. By coincidence, an empirical crisis holds cosmology in its grip in which fiddling with the usual culprits (like the star formation rate in young galaxies) seems insufficient to rescue the big bang model. In
,.:;uch a situation, even an at first sight alien, chaos-borne ray of light can acquire a warm glow.
Acknowledgments
I thank Christophe Letellier, Heinrich Kuypers, Dieter Fröhlich, Normann Kleiner, Peter Weibel, Erwin Wendling, Hans Diebner and Florian Grond for discussions. For J.O.R.
References
[1] O.E. Rossler, D. Fröhlich and N. Kleiner, Time-symmetric Hubble-like law: Light rays grazing randomly moving galaxies show distance-proportional redshift. Z. Naturforsch. 58 . 807-809 (2003).
[2] O.E. Rossler, Cosmic shear's temporal fluctuations generate a distance-proportional redshift in both time directions: Minibang theory. Chaos, Solitons & Fractals 12, 1335- 1338 (2004).
[3] A. Loskutov, A.B. Ryabov and L.G Akinshin, Analysis of billiards with time-dependent boundaries. Facta Universitatis Series Mechanics, Automatic Control and Robotics 11, 99- 116 (2001).
[4] B.B. Mandelbrot, CR. Acad. Sci. Paris A 280, 618 (1975).
[5] M. Seldner and P.J.E. Peebles, Astrophysical J 215, 703 (1977).
[6] A.K.T. Assis, "Relational Mechamics." Montreal: Apeiron 1999.
[7] P.J.E. Peebles, Principles of Physical Cosmology. Princeton University Press 1993, p. 226.
[8] O.E. Rossler, "Darkness intensified: Existence of a nonlinear threshold in redshift induced dimming." Z. Naturforsch. 54, 453-454 (1999).
[9] A. Einstein, Does there exist a gravitational effect analogous to electrodynamic induction?
"Collected Papers," English Translation edition, Vol. 4, pp. 126-129. Princeton University
Press 1996.
[10] O.E. Rossler, A morphogenetic instability in gravitation. Physica D 2004 (invited paper submitted).
[11] The term "Fermi acceleration" was already reserved by Loskutov et al. [3] for a different mechanism (the heating-up of billiards subject to repetitive head-on collisions with moving boundaries). Thus, a new term (“Einstein acceleration”?) will be needed for the present mechanism which has nothing to do with billiards and, by the way, does not extend to light, provided it is going to be confirmed.
[12] S.W. Hawking, Particle creation by black holes. Commun. Math. Phys. 33, 323 (1973).
[13] R. Giacconi, Kepler lecture, held at the University of Tübingen, July 2003.
[14] J.-M. Bonnet-Bidaud, Le big bang face à ses contradictions, Ciel&espace No. 412, 42- 44, September 2004.
[15] Editorial: Mature galaxies in young universe at odds with theory, Scientific American online, September 2004.
Remark added in 2020: Since this paper was written in 2004, Cryodynamics – explaining cosmology causally for good – got discovered; so this text remains just a step on the road.
Physics is one of the physical sciences. The two other physical sciences are chemistry and astronomy. Astrophysics is the branch of physics that deals with space and celestial bodies.
If the Earth going through space would be close to a black hole, it would be gone to the center of it. Perhaps it is surrounded by low-density air
My questions are:
1. Could exist a black hole there without eating Earth surrounded perhaps by vacuum?
2. If it is possible that the black hole generates a lot of energy in the out border of the event horizon that could explain that the Earth heating is about twice the received sun power?
3. If it could explain the Earth magnetic field
4. It's mass
5. How to detect it
6. If it is true, perhaps earth temperature is higher than several million years before. It is known what was the Earth temperature then?
I make these questions because I am worried about the danger of generating a stable black hole in a scientific test. If one of them were created, it would go to the center of the Earth eating earth generating a thin tunnel.
Carroll and Ostlie in An Introduction to Modern Astrophysics, second edition at page 1099 remark: “Cosmological redshifts are caused by the expansion of the space through which the light travels, so for extremely large distances the total elongation of the wavelength depends on how the expansion of the universe has changed with time.” The 4/3 laws are based on dimensional capacity and imply a distance in 3 dim space stretches by 4/3 compared to the same distance in 4 dim space-time. Is there a connection?
It may be a binary black hole accretion disk or an AGN.
Can anybody please share the IDL source code for Hapke photometric modeling?
Thank you,
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.
astrophysicst
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:
Agree? Disagree?
Astrophysical S-factors for thermonuclear reactions that produce electron neutrinos.
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 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!
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.
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?
Normally, people apply plane-wave analyses even in a curved geometry, often irrespective of wavelengths. It is mostly encountered in the area of astrophysics and space sciences, even without considering any inter-dependency between the perturbation wavelength and the radius of curvature. What is the main justification?
Can I get some references on the planar-nonplanar wave connectivity and inter-transitional behaviour?
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
[((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
Once again, as JPG image
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 19th century and/or at the beginning of the 20th century. Even the contemporary quantum physics, astrophysics, and AI of the 21st 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: TH = 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,
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
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
