Astronomy & Astrophysics

Astronomy & Astrophysics

  • Madhu KASHYAP Jagadeesh added an answer:
    Is GJ 581 g undetected because it's too close to GJ 581 d?
    In the detection of exoplanets usually the (RV)-(radial velocity method) is used. However, there is dispute according to some scientists that Gliese 581 g in its (HZ) does not exist because it could not be detected with either the HARPS and or HIRES data sets because of red noise etc. However, the discoverer of the proposed GJ 581 g exoplanet mentions that both HIRES and HARPS data sets were needed in order to detect this exoplanet. My point is that what has never been thought about-(which I bring out in this new paper), that to detect an exoplanet successfully takes many years and attempts to detect an exoplanet certain number of time successfully. My point is:"That in the Gliese 581 star system it is proposed that Gliese 581 g and Gliese 581 d are in the narow banded (HZ) habitable zone. If so, than if they are relatively close together, it could be a situation where sometimes Gliese 581 g is truly detected. However, other times Gliese 581 d is detected as well. But, if the exoplanets are relatively close together sometimes the (RV) amplitude detection signal could be picking up either exoplanet. making it appear that Gliese 581 g does not exist. Please read the paper it goes into much more detail than this and provides new formidable evidence to help determine if Gliese 581 g exists or not.
    Madhu KASHYAP Jagadeesh

    Is this not verified by transit method ? 

  • Nainan Varghese added an answer:
    What is the gravitational force? How does it exist?
    Is anyone have an explanation? Thank you =)
    Nainan Varghese

    Dear Palmer,

    Thank you very much for the feedback. As the said article is a very small part of an elaborate concept, it would not give detailed explanations on spatial dimensions or their implications. Your deductions about spatial dimensions are correct. I also believe the same; that all real entities exist in all available spatial dimensions. Only such existence can provide them with positive existence and objective reality.

    However, a plane that we consider as 2D object is considered to have zero thickness. An object that has zero thickness cannot have positive existence in space. Nevertheless, great many number of parallel planes in contact may occupy volumetric space (making it a 3D object). Here, ‘zero thickness’ can only mean that the thickness is so small that it is intangible by using any of the standards, we use. It is in this sense I use 1D and 2D spatial dimensions. A 1D entity has positive existence in all spatial dimensions. However, its existence in single spatial dimension is tangible and in any higher spatial dimension, its existences are intangible and hence zero. For more details, kindly refer Chapter 2 (available at of my book ‘MATTER (Re-examined)’.

    We deal only with structured matter bodies, which have tendency (under gravitational collapse) to grow into all available spatial dimensions. Thus, they tend to become spherical in shape. Contrary to this, unstructured matter has tendency to reduce its existence into minimum number of spatial dimensions. A 3D lump of unstructured matter tends to become 2D / 1D object (with intangible measurements in one or two spatial dimensions). For brief description, see: . This phenomenon is the basis of creation, existence and destruction of universe and its contents, as we observe. Logical explanations to all physical phenomena (including gravitation and gravitational attraction) can be derived from this strange behaviour of unstructured matter.


  • George Stoica added an answer:
    Can fracture mechanics predict when the whole Universe will fracture?
    This question is open for chemists, metallurgists, physicists and astrophysicists:
    Check out this diagram which has been released today on Universe inflation. It describes how the universe has been expanding with time. It says that the Universe, around 2 billion years after the Big Bang inflated at a rate of 1% every 44 million years. The expansion decelerated under the influence of dark matter before the expansion continued under the influence of dark energy.

    Now Let's look at another [quite similar] diagram, called creep diagram:
    The diagram describes the elongation of a structure under a static load with time, across three stages before fracture.

    It happens that a certain concept in a scientific field can be used to describe (and predict) a phenomenon in a seemingly (and sometimes totally) different scientific field.

    Can these two diagrams help make the case, one day?
    George Stoica

    Fracture mechanics cannot predict anything, it's an exact science, with answers in black and white. And I do not know of any attempts of mixing fracture mechanics with probability theory or quantum mechanics. 

  • Dongchun Zhu added an answer:
    Can anyone help me find the formula of the precision of differential photometry of one dataset?

    Hi, I am trying to find out the formula to calculate the precision of differential photometry. IRAF or SExtractor can give magnitude errors, but these errors are usually given as instrumental errors, therefore ignoring the errors introduced by the different extinction behaviors of comparison star of unknown spectral type. The possible intrinsic variation of the comparison star is usually not addressed. Besides, bias frame and dark current and flat field calibration error also exists. However, there is still not a unified formula to calculate these potential error for the time being. I've been puzzled by above problems and would greatly appreciate your comments and suggestions.

    Dongchun Zhu

    Thank you for your suggestion, Diego. In fact, I have made a talk on Diego+10 in one my group meeting. My mentor Prof. Tinggui Wang and lab brother Ning Jiang said C-statistic, one of four test methodologies, detects no flux variations in AGNs, which maybe have some problem in your parameter. In your paper, you recommended that we should take the instrumental magnitude error (calculated by some photometric tool) times a constant, usually 1.5, as final stadard variation of magnitude, which will be used in chi-square test. I admit that I have often used one-way ANOVA test and chi-square test to test AGNs microvariability. But now what I am doing is another work, high-precison differential photometry, which will calculate the most perfact and accurate photometric error. Based on my work, planetary transits and other microvariability, e.g. less than 0.01 magnitude order luminosity variability, can be well detcted and comfirmed.

  • Victor Christianto added an answer:
    Is there global gravitational potential associated with local galactic cluster and beyond?

    In an old paper, Dr. D.V. Ahluwalia suggests that the Great Attractor embeds us in gravitational potential at the order of -3x10^(-5).

    Interestingly, one of my colleague (Michael Peck) also suggestes that there could be global gravitaional potential affecting the entire Universe. So what di you think?

    Victor Christianto

    Dear Dr. Ostrovskii:
    Thanks, yesterday i just downloaded your paper on PFO theory, will find time to read it.

    Btw, you can find my recent question here:

  • Victor Ostrovskii added an answer:
    Can the initial singularity be removed from cosmology models?

    In a rather old paper, Michael Heller argues that in certain cases it is possible to remove the initial singularity from cosmology models. He discusses b-boubdary and noncommutative geometry. So what do yo think?

    Victor Ostrovskii

    The PFO-CFO Theory contains no singularity (see my and Elena Kadyshevich ResearchGate pages). 

  • Roger M. Pearlman CTA added an answer:
    What is the astrophysical nature of the observed cosmological redshift?
    In recent astrophysical literature there are splashs of acute discussions on the interpretation of the observed cosmological redshift: is it space expansion, the Doppler effect of receeding galaxies or the gravitational effect of cosmologically distributed matter. The question is how to distinctly observe these different interpretations of observed properties of cosmological redshift.
    The problem was formulated by H.Bondi (1947) and also by E. Harrison in his book “Cosmology”, Cambridge Univ. Press, 1981 (second ed. 2000). Now there are more than ten papers which argue the different possibilities. Abramowicz et al.(2007; 2008) demonstrate that only space expansion can be used for understanding the cosmological redshift within general relativity, while Chodorowski (2007; 2011), Bunn & Hogg (2009), Melia (2012) insists on the interpretation as the sum of the Doppler effect plus the gravitational effect.
    In general relativity space / space-time itself has the same level of existence as matter (Einstein equation joins them) so the space can be curved, stretch, spread (as gravitational waves) and so on. And this also can be considered as an argument in favor of the expanding space interpretation, though the problem is still open.
    Roger M. Pearlman CTA

    'The Pearlman Spiral' an alternate hypothesis on the cause of Cosmological Redshift (CR) might help answer the opening question as it it greatly reduces the time it took for that CR light to reach us from where it originated. So much less time for gravity to pull on it..5776 years versus up to about 13 billion years.
    Also assuming valid, The Pearlman Spiral also explains why CR is more consistent with a static universe than an expanding one. Which falsifies the standard model.
    Formulated in April of 2013, if able please review and recommend to the extent warranted,
    roger m.

  • K. G. Hełminiak added an answer:
    Oort cloud in binary star systems?

    Does anyone know if there has been a study on Oort Cloud formation in binary star systems?

    K. G. Hełminiak

    If the binary is not very wide, i.e. separation between components is not hundreds or thousands of AU, I see no reason why an Oort cloud could not form in a manner similar to our Solar system.

  • Raul Simon added an answer:
    What is really serious about "Oort's Cloud"?

    Can we see something like this around any other star?

    The Oort's idea was surely born upon his correct consideration that Nature "don't accept nothingness". The difference between the traditionally considered distances to the (then) last planet Pluto and to the nearest next star (alpha Centauri group) was too large a space containing "Nothing", so this space has been imagined to be filled out with myriads of cometary bodies. But today we know much more about the interstellar space. We know, there is no vacuum there outside. Why do we still need the concept of the "Oort's Cloud" at all?

    Raul Simon

    Thank you, James and Dr. Neslusan.

  • Maxim Eingorn added an answer:
    An old question that is still fresh: Is gravity a Newtonian force or Einstein space-time curvature?
    No gravitational wave was measured yet, no graviton was detected accordingly. On the other hand no space- time curvature was observable. There is no successful experiment to validate the current theories. What is the nature of the mysterious gravity? What is the velocity of this effect ?
  • Nicolai Herrmann added an answer:
    Who will assist me in developing a new theoretical concept on our oceans' formation - ?

    Hello and thank you for welcoming me here.

    I am thrilled to announce that I seem to have developed an in itself seemingly "water-proof" raw theory on the formation of our (and any) planet's oceans. (Please check the attached file for a short rough concept paper).

    So far, noone I know was able to refute it - so I now seem to need some mathematical and educated assistance/peer review for further development into a proper scientific paper (lacking the skill set in mathematics and detailed education).

    The job would be, to discuss/"bombard" my ideas from a professional point of view, to assess and futher expand my source material for my upcoming long form of the attached, at this point still source-bare concept paper, and to do some math, where necessary. My goal (or you might call it "dream") would be an accepted article in a renowned science magazine.

    If there is anyone out there, willing to partner up - please let me know. I would offer a full equal partnership in this brand-new theory (already documented in different locations on the web, in its raw colloquial form). Even one single trained helper might suffice, as of now. It would literally mean "the world" to me :-) – and maybe to all of us, if you agree in the validity of the thoughts conveyed. Not a small thing, is it?

    Nicolai Herrmann

    Nicolai Herrmann

    Thank you very much for this crucial input - so there is much of my thoughts in this, to be sure (minus the link to theia). Very interesting. I initially just was irritated by the lack of alternate information i could obtain through established channels. The wish of not taking short-cuts by the way can be seen as the cause of this post, so none intended. :-) But I deeply appreciate you taking your time, still. Thanks. We will see, how this further develops. :-)

  • Gengis Kanhg Toledo added an answer:
    What are essential and nice features to have in a telescope control system?
    I am currently writing software to control a small refractor (125 mm). Drive motors are brushed DC, encoders are 10 000 ppr mounted on the motors, gearbox has 1:8000 ratio. The German equatorial mount is well built and solid. The observer's software has a GUI and writes directly to Excel spreadsheet using dynamic data exchange (DDE). Another program communicates with the servo drives, and receives pointing information and other instructions from the GUI, via Excel spreadsheet. So both the GUI and servo control software can exchange data via DDE and both can read and write to Excel spreadsheets, allowing data plots, simple statistics etc. Currently the software has a fair number of GUI accessible functions. What would you expect a telescope control program to have as a must, and what would you like if you could choose features?
    Gengis Kanhg Toledo

    I support the ideas of Nicolas Produit in order to design and develop using standards and do not inventing the wheel, instead of that, cooperation using the free software model in order to improve TCS. For many large grounded based telescopes it is used Linux/CentOS, and VxWorks for such critical RT functions. Interoperability, maintenance, upgrade-ability and long lifespan should be attended in such developments.

  • Ingila Rahim added an answer:
    How can we calculate the depth of convective zone of sun like stars or envelope of stars?

    I want to know when the convective zone of any star start to begin and what is the thickness of convective envelope. 

    Ingila Rahim

    Thank you sir Ken and madam E Nihal.

  • Amrit Sorli added an answer:
    Could Planck constant be a function of the gravitational potential?
    Kentosh and Mohageg looked through a year’s worth of GPS data and found that the corrections depended in an unexpected way on a satellite’s distance above the Earth. This small discrepancy could be due to atmospheric effects or random errors, but it could also arise from a position-dependent Planck’s constant.
    • Source
      [Show abstract] [Hide abstract]
      ABSTRACT: Based on several assumptions to deduce a cosmological model with three fundamental constants along with the dimensionless electroweak coupling constant turned into functions of the gravitational potential. Initial research of this model has indicated solutions to avoid the singularity in both special relativity and general relativity.
    Amrit Sorli

    they both depend on density of quantum vacuum

  • Ingo H Leubner added an answer:
    Is dark energy merely an illusion?

    According to a report by Carlo Iorio and Timothy Clifton, dark energy may be an illusion. And LTb model or variations of it can be promising candidates to get rid of it. What do you think?

    Ingo H Leubner

    Dark Energy and dark Matter were introduced in cosmology when observations were made that did not agree with Newton’s models and other observations.

    Mainly, rotational behavior of galaxies were observed that could not be explained with ‘earth’ physics. Once the concepts of dark matter and energy were established, they became the daily tool of astronomers on large telescopes. I could solve many of observed astronomical enigmas (un-solvable puzzles) using standard ‘earth’ physics.  For instance, see my publication at Researchgate about ‘Why and When a Wet Mars?’. It changed -3.6 Byrs ago, and was concurrently derived from observations on Mars. Thank you for your interesting questions! Ingo

  • O. M. Guilera added an answer:
    Does anyone know about planet migration and outcomes?

    It has been shown (in 2010) that planets which undergo Type I migration usually migrate towards a point in the disk called as "planet trap".

    I am curious what will be the result if many planets in the disk migrate towards the same planet trap. Will they collide causing fragmentation or forming bigger planets? Or maybe they wont collide and start orbiting around their center of mass?


    O. M. Guilera

    Dear Antranik,

    here there are some references about your concern:

  • Ingo H Leubner added an answer:
    Is Hubble's Constant really a constant? Or just a parameter?
    Hubble's constant gives the expansion rate of the universe and the universe is accelerating. So does it mean that the Hubble's constant itself is changing? Why call it a constant then?
    Ingo H Leubner

    The reality-based derivation of H0:

    U3b, Reaction Kinetic Expansion of Universe Note: Abstract included

    Technical Report: U3b, Reaction Kinetic Expansion of Universe ; Author: Ingo H. Leubner, Dr.rer.nat.
    DOI: 10.13140/RG.2.1.3387.4084

    The publication above contains the full discussion, and a review of classical H0 derivations. Vetted 365 H0 measurements from between 1996 and 2010 resulted in a range of H0 from 30 to 89. The average is 67.3+/-9.1. The data clearly indicate that the measured values of H0 yield not a constant. The classical modeling does not provide estimates of an average H0 value. The parameters that make up the classical calculations have not been related to experimental results or measured observed factors in the Universe.

    In contrast to the classical derivations, the modeling of the expansion of the Universe is based on classical understanding of astronomical processes, and on the observation of mass-conversion to photons by all galaxies and stars. The mass-loss rates of the individual radiating objects may vary. An average loss-rate was deducted by averaging individual rates and their relative weight percent, which is standard modeling.

    The process of the over-all rate of mass-loss rate, ku , and its effect on the expansion of the Universe is based on standard mathematics. The result reveals that the expansion rate, H0, is related to the average mass-loss rate ku. The value of ku was calculated using the observed average H0 value of 67.3 +/-9.1. The result is that ku = 0.138 +/- 0.019 [1.0/Gyr)].

    For full information and results, please, read the attached ResearchGate manuscript.


    • Source
      [Show abstract] [Hide abstract]
      ABSTRACT: U3b – Abstract, Reaction Kinetic Expansion, Decay, Re-Formation, and the Hubble Correlation of the Universe Ingo H. Leubner, Dr.rer.nat The present manuscript is an update over the previous submissions to ResearchGate. The first needed editorial clarifications. Updated submissions to R-gate manuscripts were incomplete when they were opened, although the submitted pdf-files were complete. For the present manuscript previous errors were taken care of, starting with the MS-Word file. Ingo H. Leubner Abstract The concept of the Expansion of the Universe is based on the observation that galaxies were moving away from Earth. It was observed separation-rates increase proportional to their distance, R, from Earth (‘Hubble-correlation’). The underlying observations suggest that the Universe is expanding. The ratio of separation rate to distance, [(dR/dt)/ R], appears to be a constant which is known as the ‘Hubble-constant, H0’. However, a plot of over 360 observed H0-values vs. time of observation shows significant variability. This suggests that other factors are contributing to these data. To relate the Hubble-constant to the theory of relativity, five different classical H0 correlations were proposed. However, none of these models provides any causality for expansion or other observable predictions. Starting from classical physical knowledge, the present reaction-kinetic model predicts the expansion of the Universe, the Hubble-constant and its relation to the universal radiative mass-loss rate. It also provides suggestions why the average value H0 has high variability. The Model: The present model of the expansion of the Universe is based on reaction-kinetic mass-loss of the Universe. For modeling, certain assumptions (theorems / axioms) are defined :(a) The Universe is a closed Newtonian system of uniform mass distribution, (b) All light-emitting stellar and galactic entities lose mass and thus gravity, due to radiative mass-to-photon conversions. (c) The overall mass-loss rate, ku, of the Universe is the weighted average of first-order loss rates of all radiating objects. (d) The mass –loss causes gravity-loss. (e) The mass / gravity loss rate determines the separation-rate between the objects of the Universe. (d) The model does not include traditional hypothetical assumptions like dark matter, negative energy, shape factors, scale factors, and cosmological constants. Page 2 of 2 June 18, 2015 Correlation Results:  For radiating objects in the Universe, the correlation between their separation rate dR/dt and distance R is linear.  The ratio of separation-rate and distance is a constant, in agreement with experimental Hubble-constant determinations and thus the predicted constant will be referred to H0.  The model predicts that H0 is equal to one-half of the universal radiative mass loss rate, that is, H0 = 1/2 ku , and ku = 2 H0;  Further modeling predicts an acceleration of the expansion of the Universe. Its value, H0’, is equal to ' 2 2 0 u 0 H =k =4H .  Quantitative Results:  The average of experimental H0 value is 67.73 +/- 9.09 [(km/s)/Mpc], which predicts that ku =0.138+/-0.0186 [1.0/Gyr].  This rate for ku leads to the conclusion, that the present mass of the Universe is equal to One Tenth of its original mass.  The variability of experimental H0 values is probably the result of their observation from Earth, which is not at the Center of the Universe.  Another contributing factor may be the observed irregular mass-distribution (‘lumpiness’) in the Universe, where local mass loss rates, kc, of a galaxy or galactic cluster may differ from the universal mass loss rate ku.  It is suggested that from the different positions of Earth and the center of the Universe, it may be possible to correlate the observed Hubble constants with the locations of their reference galaxies relative to the location of the center of the Universe and relative to the location of Earth.
      Report number: U3b-Hubble, Affiliation: Rochester Institute for Fundamental Research
  • Hitesh Changela added an answer:
    Are there any "Triple Planets"?

    Double planets- two planetary mass objects orbiting each other- have already been detected.

    My question is whether or not "triple planets" exist? In fact, are there any detections? If there are no detections, what are the reasons which prevent triple planets to exist? I even see that it is not classified as planet type in the link below.

    I really appreciate all the answers.

    Hitesh Changela

    That's cool! I guess I was trying to get at some conditions for a planet to be a planet in the first place. Let's take our favorite Pluto. Pluto and Charon don't have the barycentre in their volumes, correct? So is that a binary system of dwarf planets? Then think of Mars, clearly it has 2 moons. In that system of Phobos, Deimos and Mars can it be justified to have that as a system of 3 planets rather than exclusively a planet and 2 moons? I'm just shooting the breeze here, but great Q & A!

  • Ivan Grosz added an answer:
    How significant is the discovery of Kepler-186f, an earth-sized habitable zone planet?
    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.
    Ivan Grosz

    No objection, but my calculations give an overview of all possible galactic habitability scenarios based on non-controversial mathematical principles.  My few basic assumptions try to help identify the high probability scenarios. The conclusion is straightforward. Existence of a substantial number of habitable planets with advanced civilizations most likely distributed over the Galaxy's habitable time span.

  • Igor Urusovskii added an answer:
    How do cosmologists determine the curvature of the universe based on astronomical data?

    Almost all cosmologists agree that the curvature of the universe is “flat” (k=0). Obviously this conclusion is based on solid astronomical observations - data. My question then is: Is there direct observational evidence that shows the universe is flat or is this conclusion solely a model-dependant parameter?

    Igor Urusovskii

    I. A. Urusovskii, Multidimensional   Treatment of the Expanding Universe,

     Physical Science International Journal, 4(8): 1110-1144, 2014

  • Reed Schmell added an answer:
    Does anyone know of any commercial high-reflectance (>98% in 300-400 nm) mirror film (thin flexible film)?
    I am looking for reflective mirror film (specular flexible film) which has high reflectance (>98%) in the UV region (300 - 400 nm) in order to use it in our astrophysics project. There are some products in the market (e.g. ESR by 3M), but all of them do not have high reflectance for wavelengths below 400 nm. It is technically possible to make such film if multi-layer coating is used, but a custom order will be very expensive.

    I would very appreciate it if you could tell me any nice products.
    Reed Schmell

    You can coat Mylar or Upliex with an Enhanced Al coating using reactive DC magnetron sputtering.

  • G. Bothun added an answer:
    How does the chemistry of the secondary MS star change before and after the CE phase?

    I am trying the understand the chemical evolution of the secondary MS star of a pair of close MS binary. When the primary star evolved and had the envelope ejected, C/N/O would be accreted by the secondary hence there would be enrichments (Marks & Sarna 1998). However, what happens to the heavier elements, do we assume the primary and secondary MS stars have the same, for example, [Fe/H] throughout the evolution?

    G. Bothun

    well that changes the situation considerably so yes, both stars should have the same Fe/H as there is no ability for local enhancement.  Only accretion of heavy elements from the ISM would change the surface Fe/H on the WD but that WD would have had to have been exposed to the ISM for a few Gyrs for any effect to occur.

  • Douglas Frederick Drye added an answer:
    How do we know Earth's precession period is 26,000 years?
    How do we get this measurement since man has not yet measured a full cycle of precession. In 26,000 years (or whatever the exact time is) will Polaris be in the exact same position, or is there likely to be some kind of variation?
    Douglas Frederick Drye

    This paper will probably tell you more than you could ever want to know about the question: 

  • H Chris Ransford added an answer:
    If it's confirmed that there has been something before the "Big Bang", what do you think about that "something"?
    Is anybody able to Imagine "Nothing" before the big bang? Does it mean no time and no space. Well, I cannot imagine there were nothing before the big bang. I think it might be something. But what about "something"? For me, this is the main question?
    H Chris Ransford

    Stefan, it may be all a bit more complicated, and independent of questions of semantics. Very many models of reality demand that time itself pre-exist the Big Bang for it to be able to happen in the first place (see e.g. Martin Bojowald , etc.) Then there are the issues of incompressible uncertainty, which prevent pinpointing infinitely exact moments in time.  Then there is the possibility that the topology of time is so counterintuitively non-linear that we are unable to grasp it properly (there are environments when this is demonstrably the case.) Then there is the possibility that time itself is an illusion, a side effect emerging in the lower dimensions of a purely mathematical universe. And so on ...

  • Alexander Chepick added an answer:
    Are the small anisotropies found in the cosmic microwave backgroung also evidence for the accelerated universe?

    I am an observational astrophysicist. From my perspective, the type Ia supernovae are the most important and clear evidence for the present accelerated phase of the universe. However I read a theoretical paper arguing that the very small anisotropies found in the CMB are also evidence for the accelerated expansion. How come? What is the realation?

    Alexander Chepick

    Dear João,

    If we assume that GR applies to the whole Universe, that there was a Big Bang, then you can do some of the conclusions, and if we assume that the universe is static and GR are not applicable to the entire Universe, then the conclusions will be quite different.

     You does not must write in answer to your question, "there was the beginning of times, there was recombination," as about established facts. You need to answer:
    "If we assume that the Einstein equations are applicable to the entire Universe that the universe is expanding, starting from the moment when nothing was, then ... .

    But if we assume that the universe is eternal, infinite and static, then ..."

    Уважаемый João,
     Если предположить, что GR применима ко всей Вселенной, и если предположить, что существовал Большой Взрыв,  то тогда можно делать одни заключения, а если предположить, что Вселенная статическая и GR неприменима ко всей Вселенной, то тогда выводы будут совсем другие.

    Нельзя в ответе на ваш вопрос написать, «было начало времен, была рекомбинация», как будто это установленные факты. Нужно отвечать:
    «Если предположить, что уравнения Эйнштейна применимы ко всей Вселенной, что Вселенная расширяется, начиная с момента, когда вообще ничего не было, то ….
    А если предположить, что Вселенная является вечной, бесконечной и статической, то …» 

  • Stefano Padovan added an answer:
    Could it be a new discovery?

    This picture was taken through my telescope (150/1400) from Tripoli (north of Lebanon). Briefly, the story of this picture is that when I was taking arbitrary pictures of the sky with my camera which was connected to my telescope, I saw something strange -maybe never seen before- (a group of blue stars surrounded by a group of red stars, attached photos). I thought that the blue dots were “Neptune” planet, but after focusing I have deduced that my thought was false because I saw a group of blue stars surrounded by a group of red stars. I didn't recognize what I saw but I was sure that it wasn't an artifact or an out of focus picture. To identify this picture, I have asked many specialists and amateurs of astronomy for help and explanation. None of them gave me a convincing answer. Some of them told me that it was a globular cluster, others talked about planetary nebula like ring nebula or owl nebula. Many specialists asked me about the coordinates of that location (RA/DEC) but the problem is that I didn't take into consideration these parameters and I can't review it now because I don't know its exact location in the sky. Keep in mind that there were no lights in the street, the place was totally obscured. The size of these points in the picture is not their actual size but red points appear only after enlarging it many times. So, before zooming there was only blue points and after zooming red and blue stars could be seen.

    + 1 more attachment

    Stefano Padovan

    For sure is a bright star out of focus plus artifacts from the camera.With that instrument you cannot have colors like that neither a globular cluster big like that

  • Robert Shuler added an answer:
    What is the three dimensional external graphical representation of black hole?


    Robert Shuler

    While Naima did not specifically ask about internals, Eric's diagram is better than others I've seen at showing them.  It is also useful for answering a specific type of question ... where can something go?  The little funnels give the space of future possible positions.  I would call this a "data plot."

    I've heard (or read) others, mostly teachers writing pedagogical papers, swearing by the time vs. one spatial dimension plots, but I never got anything out of one (except for Eric's just now).  You cannot get curved space that way because in one dimension, according to the conventions of differential geometry, variations in the spatial distances in one dimension can always be transformed away.

    There is an interesting underlying problem with interpreting these plots as more, as a visualization of coordinate space.  The "convention" to drop the "i " from in front of "t " (adopted after I left school in the mid 70s) hides the fact that time is not a true coordinate, at least not in the same way as spatial dimensions.  Nothing can move about freely in time.  4-space is not a space.  It is 3-space with a Lorentzian relationship to time.

    You can't look at a time-radius or a time-x plot and make correct inferences about the distances between points, which is an essential geometric quality written in human genes.  Therefore such plots are misleading to humans.  What you have is:

    Minkowski: ds2 = dr2 - (c·dt)2

    Euclidean: ds2 = dx2 + dy2

    In my view, only when one "gets over" the Minkowski space thing, is one able to actually understand and visualize space-time curvature.  Humans in their ordinary experience do not visualize time.  They visualize and see space, and motion.  Based on the number of downloads, and other feedback, the projection graphic I presented is probably the most useful graphic I've ever created on any subject.  People find they can understand it.  Especially the two interpretations of length contraction vs. space expansion. 

    If you want to represent an object moving, other than in a plot, you have to resort to animation or video or some type of multi-frame drawing.  Both plots and representations have extremely valuable uses.  I don't know which Naima was looking for, but it's nice to have both.  I just wanted to clear up the difference since so many people have suffered from incorrect interpretation of the Minkowski space-time "plots."

  • Michael Issigonis added an answer:
    There is a dark ring on an asteroid, is it noise in the picture? or not?

    Hello, As you can see in the picture, there is a dark ring on an asteroid, is it noise in the picture? or something else? totally it is like a ring not a burned pixel. 

    Michael Issigonis

    Is it possible that the "speck" maybe a micrometeorite hit on the glass of the window or of the lens that took the picture?

  • H. T. Liu added an answer:
    Does a gravitation wave change propagation direction passing near a massive gravitation center (star)?

    As we know light wave passing near a gravitation center (star) changes its propagation direction. Is this true for a gravitation wave? 

    H. T. Liu

    Whether or not the  waves (electromagnetic or gravitational) propagate along the same directions in the Universe will depend on the spacetime. The curved spacetime will make the waves travel along the curved  trajectories. so, the gravitational waves will be deflected as passing near a gravitation center.

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