This is an open group for those who are interested in the field of cosmology.

• Kaveh - Shirazi

  How can I create a list of eclipse binary star data?

  I need some data about eclipse binary stars such as Apparent magnitude. Spectrum, Period, etc.
• Prakash Kumar

  What are the differences between a massive black hole and the scenario just before the big bang?

  It is believed that the universe began from a primeval fireball. The structure which exploded as a primeval fireball seems to be akin to a massive black hole. But many people would like to make aIt is believed that the universe began from a primeval fireball. The structure which exploded as a primeval fireball seems to be akin to a massive black hole. But many people would like to make a difference between the two. Let them answer this question in a satisfying way.

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  • 
    Robert Singleton replied

    I would like to return to the basics of the original question: What is the difference between a massive black hole and the instant before the Big Bang. To talk about "before" the Big Bang can beI would like to return to the basics of the original question: What is the difference between a massive black hole and the instant before the Big Bang. To talk about "before" the Big Bang can be tricky, because from the point of view of our universe and any creatures who live there, there was no "before". The Big Bang was not a normal explosion of debris, like a bomb or an exploding oil drum, it was an explosion *of* space and time itself, fueled by local energy density and pressure of the subatomic environment embedded in the very space that is undergoing the expansion. But it's possible that there might be another region of a "larger" space-time in which our Big Bang took place, and perhaps many other Big Bangs as well. Think of a boiling pot of water, with each bubble in the pot corresponding to a specific Big Bang and subsequent creation of a different universe. Note: I don't think the singularity question is really the issue, because, when we finally quantize gravity, the singularity of classical general relativity will likely turn out not to exist (it will turn out to be a highly dense state in which quantum fluctuations halt the collapse to zero radius and infinite density). Anyway, on to other things. Nobody knows what started the Big Bang (although that in no way affects the truth that our universe indeed arose with one such "Bang" ... the evidence is indisputable), but one theory prosed by Andrei Linde and others goes that there exists a primordial Mother Universe, maybe a simple scalar field theory with very little structure itself. Quantum fluctuations will continuously sprout off Baby Universes from the Mother Universe, each of which would undergo its own Big Bang and subsequent expansion and cooling (each Baby Universe might have its own laws of physics, including a different number of spatial dimensions). All such theories that I know of are similar, relying on quantum fluctuations to bootstrap an expansion of the local space-time of the Mother Universe, and there are many variations on this theme. For example, if the universe is indeed expanding exponentially because of "dark energy" (which is most likely a non-zero cosmological constant), then in a few tens of billions of years, distant space will have reached speeds far greater than that of light, and this will effectively create a region of space around us from which we cannot escape. In other words, the exponential expansion of space-time will create its own event horizon ... in fact, many event horizons. Sound like a super-massive black hole? Furthermore, quantum fluctuations near the event horizon might create baby universes that undergo their own Big Bangs and expansion. So, it might be the case that super-massive black holes create their own universes, which in turn create super-massive black holes, which in turn ....

    23 days ago
• Karim S.B

  Cosmology

  Hi all, It's a real pleasure to join this group of ideas exchange. I am from France and Cosmology is one of my hobbies and interests. I am not a physician nor a cosmologist. I am specialized inHi all, It's a real pleasure to join this group of ideas exchange. I am from France and Cosmology is one of my hobbies and interests. I am not a physician nor a cosmologist. I am specialized in cryptography. My concern today is the origin of Universe and theory of unification. Regards Karim

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    Andrzej Lechowski replied

    Dear Raul, I'd like to reply to your post, but cannot do it at present. The reason is that some of my posts vanished. They don't appear on clicking to "Show full discussion". There are missing myDear Raul, I'd like to reply to your post, but cannot do it at present. The reason is that some of my posts vanished. They don't appear on clicking to "Show full discussion". There are missing my replies to Messrs SS and ML. There is missing my post with list of scientific myths. Is it accidental? Or there is a censorship on ResearchGate? If the latter, I won't trouble to take part in the discussion anymore, much to my regret. Best regards, Andrew

    Apr 25, 2012
• Stefano Gusman

  General Relativity doesen't explain gravity and bodies weight

  GR fails when explains bodies weight with fre fall postulate. Opera experiment suggests the existence of a three dimensianal euclidean a temporal space, in place of curve space time . Gravity is aGR fails when explains bodies weight with fre fall postulate. Opera experiment suggests the existence of a three dimensianal euclidean a temporal space, in place of curve space time . Gravity is a pushing force. In the link a double language (italian english) abstract. Do you like to discuss abt ?

  http://marius-gravity.blogspot.com/p/mt-sintesi-mt-summary.html

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  • 
    Stefano Gusman replied

    Ok guys...Rubbia is going to repeat the experiment with ICARUS in April or May,,,Let's see

    Apr 17, 2012
• AP Radha Krishna

  Is there critical density for universe so that universe expansion begin to accelerate ?

  If I am correct, the present view is that in the early stages of the universe - for a less than 5 billion year after big bang - universe was decelerating, due to gravity, then begin to accelerateIf I am correct, the present view is that in the early stages of the universe - for a less than 5 billion year after big bang - universe was decelerating, due to gravity, then begin to accelerate due to dark energy become dominant force over the gravity. Gravity turned weaker due to expansion of the Universe. Then onwards universe is accelerating due to dark energy for which Cosmologists use Cosmological Constant which actually Einstein proposed once and then abandoned. That means is this cosmological constant tells us about the critical density of the Universe? Is there any critical density - the minimum density - below which dark energy turned dominant and make the universe expand with acceleration? If so what is that equation relates density of the universe ?

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  • 
    Prakash Kumar replied

    Dear Joe Clema, I suggest you to go through the entire conversation between Bill LaPorte-Bryan and myself regarding some topics of gravitation and astrophysics. This may help you to make some of yourDear Joe Clema, I suggest you to go through the entire conversation between Bill LaPorte-Bryan and myself regarding some topics of gravitation and astrophysics. This may help you to make some of your ideas clear. The entire conversation exists in researchgate and has not been deleted.

    Mar 29, 2012
• Suraj Singh

  What causes the spiral shape of the galaxy?

  I have seen foam floating in a similar shape on swirling water surface. But Universe is hollow, then this couldn't be the cause as their is no medium. It might seem to be very childish but I wantedI have seen foam floating in a similar shape on swirling water surface. But Universe is hollow, then this couldn't be the cause as their is no medium. It might seem to be very childish but I wanted to know.

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• Hemza Azri

  These are what cosmologist and particle physicists know about the history of the expanding universe. It began with a big bang and underwent some phase transitions, in a so little period anThese are what cosmologist and particle physicists know about the history of the expanding universe. It began with a big bang and underwent some phase transitions, in a so little period an inflationary epoch has occurred !. The CMB radiation appeared when the universe was about 400000 years, the discovery of this radiation was one of the great discoveries of physics. One interesting thing that we can not see in this picture, is the so called 'Dark Energy', without this stuff we can not talk about the expanding of the universe.

  

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  • 
    Italo Ramos replied

    Of course, Brandon, I want. But, please, don't be so erudit. I love cosmology, but have to stay in its philosophy.

    Mar 23, 2012
• Lucas Hadade

  What´s the difference between a wormhole and a black hole? What happen with a material when he enters at a wormhole?

  How could we know (investigte, find out) what happen with a material, when this material enters at a wormhole? Some people did speculate a trip to another point of universe or even a trip to otherHow could we know (investigte, find out) what happen with a material, when this material enters at a wormhole? Some people did speculate a trip to another point of universe or even a trip to other dimension, other verse and wormholes whose output coincides with its own entrance. Grateful.

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• Hussain Gohar

  origin of this universe...

  there are many confusions about the origin of this universe. so lets start the notion of the greec philosophers about the origin and other things related to cosmos.

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• Obaid Ullah

  Usually we give comments about the universe after the big bang. Can we say something before the big bang.

  Before And after the universe

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• Julio Rojas

  There is some video of the Titius Bode Law?

  Titius Bode law is a coincidence?

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    Prakash Kumar replied

    Dear Julio Rojas, I do not think that the Titius-Bode Law is a coincidence. It is a mystery which requires further involvement of the cosmologists and quantum physicists.

    Mar 9, 2012
• Giovanni Leopoldo Rozza

  Looking for areas of Cosmology that rely on specialized statistical work.

  Hello, my question is more a kind of "brainstorming," I'm just looking for a piece of string to pull it out later: D. I'm majoring in Electrical Engineering and was recently accepted in a master'sHello, my question is more a kind of "brainstorming," I'm just looking for a piece of string to pull it out later: D. I'm majoring in Electrical Engineering and was recently accepted in a master's degree (graduate curse) in Industrial Engineering at UFPR in Brazil, and my research area has a strong emphasis in Statistics and Probability. I've always been interested in the field of cosmology, and since my goal within the course is to become a student with a deep knowledge in Statistics and Probability, so I imagined how I could be useful for a colleague in the field of cosmology. Asked another way: What areas of cosmology could with my professional background to develop a joint research project that could stress my skills while developing a satisfactory result?
• Stefano Gusman

  The not many elegant universe

  There are two "MT" ( "M" theories)....This one isn't properly elegant but perhaps simplier...

  http://marius-gravity.blogspot.com/2011/11/seem-logic.html

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    Jagadesh Rao replied

    @stefano,, they call it aether , we call it spacetime ,,,, no more difference... There is no arrow of time as a dimension only can have an arrow, time is not a dimension... This is illusion,,@stefano,, they call it aether , we call it spacetime ,,,, no more difference... There is no arrow of time as a dimension only can have an arrow, time is not a dimension... This is illusion,, as long as time is running we will presume existence of space..

    Jan 28, 2012
• Surender Pratap

  can any body let me know the name of any book where i can get information regarding Geodesic in gravitation.

  Like in plane ,sphere or in cone trajectory

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    Jagadesh Rao replied

    Dear Giovanni, I am a sincere fan of Albert Einstein and i will never think of disparaging his theory, I am just saying that his imagination was alright, but usage of tensorDear Giovanni, I am a sincere fan of Albert Einstein and i will never think of disparaging his theory, I am just saying that his imagination was alright, but usage of tensor calculus in the theory is not right. According to gravitational time dilation, as in GR, time just runs slower (rate of time) nearby mass ( accelerated frames ). kindly download the diagram i made for you and try to understand sir.

    

    Jan 27, 2012
• Jeffrey O'Callaghan

  In Thomas S. Kuhn's book "The Structure of Scientific Revolution" he documents the doubts that precipitate a paradigm change in scientific thought. For example, even though one could still makeIn Thomas S. Kuhn's book "The Structure of Scientific Revolution" he documents the doubts that precipitate a paradigm change in scientific thought. For example, even though one could still make accurate predictions of planetary motions using the 15 century geocentric models it became increasing more difficult to integrate that concept with the more accurate observational data provided by the new technologies of that day. This resulted in some scientists questioning their validity. He suggests the doubt generated by its persistent inability to explain new data lead many scientists of that period to adopt the simpler rules of the revolutionary heliocentric model. Modern physics appears to be on the verge of a similar revolution because the discoveries of dark matter and dark energy are extremely difficult to integrate into current theoretical models. As Thomas S. Kuhn points out failure of an existing paradigm is a prelude to the search for a new one. "The Reality of the Fourth Spatial Dimension" is the beginning of one of those searches. It demonstrates how one can seamlessly integrate the observations of dark matter and dark energy into a theoretical model based on the existence of four *spatial* dimensions and provides a unifying mechanism responsible for the four forces (gravity, electromagnetism, the weak, and strong) governing the interactions of matter, energy, space, and time. Additionally, it provides a logically consistent explanation for other observations that today's paradigms cannot by extrapolating the classical laws of three-dimensional space to a fourth *spatial* dimension. For example it shows how one can derive the contradictory wave particle duality of energy/mass by extrapolating the laws of resonance in a three-dimensional environment to a matter wave moving on a "surface" of a three-dimension space manifold with respect to a fourth *spatial* dimension. One thing you should be aware of, this book is not meant to define the answers to all of the questions found in today's paradigms. Instead we hope it will serve as a guide or a road map for further research into them. It relies less on mathematics and more on conceptual logic and thought experiments (much like Albert Einstein did) to show how one can explain and predict all modern observations by extrapolating the rules defining classical three-dimensional enviroment to a fourth *spatial* dimension. The universe's most powerful enabling tool is not knowledge or understanding but imagination because it extends the reality of one's environment.

  http://www.amazon.com/Reality-Fourth-Spatial-Dimension/dp/1456376489/ref=sr_1_1?ie=UTF8&s=books&qid=1293129052&sr=8-1