Astronomy and Cosmology

How can it be that intelligent people claim that there are black holes in the universe, e.g., at the center of galaxies, although the universe has only existed for a finite time in the cosmology they believe in? A black hole is an object whose mass is surrounded by an event horizon at which time is dilated infinitely. Such a state cannot be reached in a finite time. An event horizon is infinitely remote from an observer. This alone is sufficient to realize that black holes are merely mathematical constructs that do not exist in reality even if the universe is infinite in age. Isn’t it obvious enough that objects that need more than infinite time to form cannot exi…

May be the beginning of the rotation of galaxies due to the expansion of the Universe.When the expansion of the Universe,where there were particles with mass movement speed decreased,it is possible particle with mass appeared compact and and there where there were more paeticles with mass became the site of the future nucleus of the galaxy.The rest of the formed mass in the form of gas clouds following the core and twisted.

I've decided to read a book 'Parallel Worlds', which centers around the idea of parallel universes in near future. I am curious to know what is the science behind parallel universes. Please help?

Hi all, Last days i'm walking with a question in my mind and im not smart enough to answer it. So that's why I put it here where the smart people come. The universe is expanding, and if it has a boundary we cannot say into what. But if there's nothing behind the edge than we cannot say that we are expanding because relative to what is space expanding. From our view space is getting bigger. But from the view of space mass is shrinking. So like everything also an expanding universe is relative. The only thing you can say is that the ratio space - mass is changing. Bigbang 0% space - 100% mass Now 99,99% space - 0.0000000000000000000042% mass The quest…

These musings have been sent to the New Scientist magazine, as well as, a number of eminent scientists over the past year. To date I have received no responses. I was hoping that some one on this forum may feel able to discuss and contribute to this. **************************************************************************************************************************************************************************** For the last thirty years I have woken up at night wondering how life began. why this should happen I don’t know. As a layman I do not have the knowledge or information afforded to yourselves, and unable to go any further than my …

When speaking of the universe and parts of it, it is common for people to refer to those parts as being "in" the universe. I think this is sloppy wording. By definition if something has the position considered as "in", then there is an opposing position "out". Given that by definition the universe is everything the position of outside the universe is nonsensical. For example should the sentence: "It is the largest known star in the universe." Instead be worded as: "It is the universe's largest known star." This semantic error I believe actually causes a lot of problems with visualisation when picturing the universe on a large scale, leading to "God's eye" views o…

Just wanted to share. It is totally insane. The scale I mean, and the void.

I need some up to date solar system books, and especially about Mercury. Can you recommend me some ?

I often come across some nice astronomy pictures, but that do not warrant a thread of there own, so I thought I would make a thread where I could place some of these amazing pictures that are out there. This one caught my eye, Saturns southern auroura. http://svs.gsfc.nasa.gov/vis/a010000/a011300/a011366/

The atomic bomb demonstrates the conversion of mass-into-energy. Are there known (cosmological) phenomena which are instances of energy-into-matter ?

While it seems that some scientists/astronomers/pundits now have a fair idea about the average distribution of dust grains in outer space (one per million cubic metres, according to one source, ref. link below), I can find no such confident claims when it comes to the distribution of micrometeoroids in the interstellar medium - i.e. objects around 300 - 500 micrometers diameter (or wide). The silence here - if silence it is - intrigues me almost as much as my desire to know the answer. Maybe the answer lies in the future. Who knows? I don't, that's for sure http://science.jrank.org/pages/3656/Interstellar-Matter.html

Hello! I see subject hypervelocity stars is not very common here. Just a few threads about it, years ago. So if you're not familiar with them please read first http://www.space.com/24432-hypervelocity-stars-ejected-from-milky-way.html http://www.space.com/8801-superfast-star-shot-milky.html Quote from article: "None of these hypervelocity stars come from the center, which implies there is an unexpected new class of hypervelocity star — one with a different ejection mechanism." I would like to share my hypothesis how this could happen (at least for some of them): Hypervelocity star (or two not joined together yet, but accelerated normal stars), ejected from center of …

fig. 1 -- HR Diagram one-zone approximation for star-core pressures Assuming spherical-symmetry, and hydro-static equilibrium, w.h.t. [math]\frac{dP}{dr} = -g® \rho®[/math]. Then, discretizing that differential equation, and taking solely a single 'step', from star surface to star core (one-zone approximation), w.h.t. [math]-\frac{P_c}{R} \approx - \frac{G M}{R^2} \frac{3 M}{4 \pi R^3}[/math], or (ideal gas law) [math]\frac{\rho_c T_c}{\bar{m}} \approx \frac{3 G}{4 \pi k_B} \frac{M^2}{R^4}[/math]. PP [math]\left( 1/2 - 2 M_{\odot} \right)[/math] Observationally (from fig.1), the luminosities, of 'intermediate mass' stars ([math]1/2 - 2 M_{\odot}…

Slightly bizarre idea... 67P/Churyumov–Gerasimenko looks like two bodies that assembled loosely. I suggest instead (not even a claim, rather an idea to chew on) that it can have been one sigle, more regular body that has lost more material at what looks now like a neck. This apple core model could for instance have occured as the object's axes had a different orientation. What is now the neck was then the equator and was more or less ecliptic. It received hence more sunheat and sublimated more quickly. After the object got its shape, it tumbled to rotate around the biggest moment of inertia, or flat if you prefer. That's the behaviour of all objects that aren't pe…

Please see the following presentation at pg 15 http://www.ifa.hawaii.edu/~barnes/ast110/MilkyWay.pdf There is an image of the galactic rotation random vectors in the nearby Solar Neighborhood. It is stated: "Most stars near the Sun have random velocities of a few tens of km/sec. These stars orbit the galactic center at ~230 km/sec." Let' assume that few tens of km/sec is about 25 to 50. Hence, each star in the Solar Neighborhood, has a random velocity of about 10% to 20% with related to the orbit velocity. In this image, we see that those random velocity vectors are pointing all directions. Up, down, left and right. Therefore, if those stars will maintain their mo…

As we are all aware neutrinos have been emitted from the big bang (approx 13.7 billion years ago). Does aging impact these neutrinos? Will they decay or lose momentum ? Will there be any artifacts from the big bang after another 13 billion years ?

There are 1 to 11 Dimention is to be explored can explain this?! How is the view in these Dimentions??

http://www.vancouversun.com/technology/truth+there+Stephen+Hawking+Russian+billionaire+launch+100M/11228828/story.html There seems to be a big difference in hunting UFOs and searching for signals from far distance planets. I wish them luck. When I was a kid I saw a v shaped formation of moving lights with the Milky Way as a background. This was in Southland (NZ) where there are no city lights so the view of the Milky Way was just spectacular. It was a long time ago now (possibly in the 1960s) but I see on YT that there were other sightings of a similar v shaped lights in the 1950s. I would have to think if that was a real sighting these UFO and possibly ET…

So something can come out of nothing... No space, no time. no matter and out of nothing a false vacuum can fluctuate into existence and turn into a cosmos. Now, doesn't that mean that the concept of vacuum must exists for it to occur? In other words, doesn't that mean that something always exists, I mean if nothing existed, there is nothing, no possibility of a vacuum, no fluctuation, nada... Or am I totally off?

The article in physics.org http://phys.org/news/2015-04-gravitational-constant-vary.html indicates that even G varies and this can be because the length of our day can also vary which can also vary the atomic decay rates. But if our planets rotation varies 0.1% then our time varies as well. So is the speed of light constant or is it related to magnetic spin time of our solar sun?

How much would it take to solve the missing antimatter problem? Is there enough? Is it testable ever?

Bonjour Je voudrais savoir si les relations ci-dessous sont connus? THawking le rayon de CMB t1 / THawking le rayon de CMB T0 = (M = masse totale de l'énergie sombre inclus) unrhu accélération THawking avec le rayon de la CMB t1 / unrhu accélération THawking avec le rayon de la CMB = t0 pour la simplicité: M * t1 (t0 rayon CMB) ^ 2 * G / (M * T0 (t1 rayon CMB) ^ 2 * G ) (1) = Omega lambda t0 * rayon de la CMB t1 / (t1 * Omega lambda * rayon de la CMB t0) (2) égalités (1) et (2) sont simplifier ainsi: Omega lambda t0 * (rayon t1 CMB) ^ 3 * M T0 / (Omega lambda t1 * (CMB rayon T0) ^ 3 * M t1) = 1 qu'elle simplifie Omega lambd…

If the universe's star formation is to last around 100 trillion years and we are currently only about 14 billion years into that epoch, would it be correct to say that our (humanity's) particular slice of time is a "six-sigma" event when placed in the context of possible or potential slices of time? Not to be misunderstood though, I realize picking out any one moment from practically any range of time could said to be abnormally unlikely. What I'm referring to is the chunk of time that one would expect us to exist within, given the timeline and all of the stars existing on it. So, in the current model of the universe, would one not expect the graph of stars existing a…

When protons and electrons fuse they produce neutrons. This happens when neutron stars form. Further compression results in the creation of black holes. What happens to these neutrons ? Do they still exist in the black holes or are they converted into pure energy ?

Lightning as we know it on terra-ferma uses the conduit from a water bearing cloud to the Earth. On another planet where clouds are composed of Methane (as an illustration), :- a) Does lightning occur ? b) Does it have analogous properties ?