Astronomy and Cosmology

The current hot topic Dark Energy and Dark Matter has several explainations and stated evidence/effects, namely the assistance in the expansion of the universe of viewable cosmos/matter. One of the latest research findings is that not only is the universe expanding, but expansion is accelerating. Some of the expansion evidence is provided from the detection of redshift, Dark energy mapping etc which is all reliant on light-measurement etc. Paul Marnet published research in spring 2000 titled Discovery of H2 in Space Explains Dark Matter and Redshift http://www.newtonphysics.on.ca/hydrogen/ where he states: ' The recent discovery of an enormous quantity o…

Just a question on the general trend of % of of mass in galaxies being DM relative to there size. Do the larger galaxies tend to have more (as a percentage) than smaller galaxies? I tried a search but, at least with the keywords I used, I found no answer.

It is known that creation of iron in stars causes stars to explode. But this (to my knowledge) only happens in the most massive stars. My question is why does this only happen in the most massive stars and not in other stars like our sun?

If hot gaseous galactic halo coronae contain multi-million-Kelvin plasma, then why wouldn't such gas undergo fusion, and thereby generate gamma-rays ? Prof. Lawson claims: [math]P \approx 1.4 \times 10^{-34} n^2 T^{1/2} \frac{watts}{cm^3}[/math] [math]L = P V \approx \frac{P V^2 m_H^2}{V m_H^2} watts \approx \frac{ 1.4 \times 10^{-34} M^2 T^{1/2} }{ \frac{4 \pi}{3} R^3 m_H^2 } watts [/math] For galaxy clusters, the estimated fusion luminosity, of the cluster halo gas, could be considerable: [math]\approx 4 \times 10^{11} \left( \frac{ \left( \frac{M}{100 T M_{\odot}} \right)^2 \left( \frac{T}{100 MK}\right)^{1/2} }{ \left( \frac{R}{Mpc} \right)^3 }\right)…

Hey, How would you work out the radius and diameter of the universe?

The Milky Way is 100,000 ly across. The central bulge is thicker than our region of the galaxy. How thick is our galaxy in our region of our spiral arm? I had been looking for info about the Kepler mission search for Earth-sized planets. I finally heard in a Science Channel program that Kepler's field of view includes stars that range in distance from us between 300 and 3,000 ly. Does that mean our spiral arm is roughly 6,000 ly thick? If we were located exactly on the plane of the galaxy, it makes sense that Kepler's field of vision should include all the stars furthest from us while gazing "upward", and not the nearby stars. Kepler is following the Earth around the…

this relates to the dark matter / dark energy and why it is thought that so much of our universe is missing. I have to admit before I pose my questions that I have a strong interest in astronomy but no university or physics background. What I know and understand has come from book. documentaries, talking to others interested in astronomy, and probably to some degree my own interpretation of what I have read and watched. So please if I am wrong in my questioning point out where I am wrong so that I ccan learn rather than shooting me down in a ball of flames. If we are to agree that the universe was created in a big bang and that bang has stopped then would it …

Having observed that each galaxy is rushing away from each and every other galaxy, how exactly did astronomers finally manage to work out where to point their telescopes/instruments to look for the origins of the Big Bang? My limted understanding... is that whatever direction you glance in throughout the night sky, using a powerful telescope of course, the galaxies are always rushing away from one another, so it's difficult to conceptualize how a point of origin for the BB was settled upon?

nb- - would a MODERATOR be kind enough to change the title above to "world", as I've typed "universe". Thanks. I'm having problems with cut and paste on this site, so will try and put this YT video up on the screen. This is a topic I caught a while back within a BBC Horizon episode -- where one physicist said something like "if you think that you understand this subject, you don't, nobody does!" Thanks to Ed once again for referring me to these Stanford University YT Lectures. I came across this one so decided to place it in here rather than just watch it myself. I haven't had a chance to listen the video all the way through, it's around 50 minutes or so l…

Shalom We are used to hearing that Coulomb's law doesn't settle with the relativity principle that nothing moves faster than the speed of light, in the sence that it embeds 'Action in a Distance'. Meaning that if somthing changes in r1 at time t1, and we write the law for any t before t1+(|r1-r2|/c), (r2 is the where the test charge is) then the law doesn't represent reality, because the 'knowledge' about the change hasn't reached r2 yet. And it is often said that Gauss' law fixes that because of its local nature. But what I can't figure out is: (1) how does one settle that with one of the famous implementations of Gauss' law, the one for a spherical shell with a char…

I would like to start off by stating that i am not a scientist, i am not currently enrolled in college or have ever attended a college course. That being said i simply had an idea and was wondering if it were possible and/or how would i go about testing the theory. The idea is pretty simple it involves the big bang and inflation. I believe many scientists wonder what was space like before the big bang and what caused it. The thought i had was this, durring "inflation" all of the glaxies are moving away from each other and the center of the universe. As everything moves away from the center a negative pressure is formed. the farther they move away the greater the pressure.…

Dear all, I have to find a fast way to compute changes in the equipotential lines as the result of sudden changes in the local gravitational fields (2D space). (Caused by the destruction of a planet for example). I could recalculate everything but it takes too much time for the device on which the calculation is deployed. The environment has lots of bodies, so an analytical solution is not to consider. I compute the level lines, picking a initial point and iterating along the gradient of the gravitational force. I don't really know where to start, but I'm thinking about a local method that only propagates changes on a limited range around the "explosion". If you want …

With regards to high-gravity objects, such as neutron stars and black holes, I've been studying the excellent Xaonon Hawking Radiation Calculatior, which I found elsewere in this forum. I have just one question: what are 'surface tides'? I understand surface gravity and the tidal effects of gravity at varying distances from the star in question. But surface tides is something I just don't get.

A new documentary has just come out that discusses comets from an electrical point of view. They are asking for a community review of the information provided before the film goes to production.

Hi I understand that micro-black holes probably don't exist in nature - at least it would appear to be the case, according to current received wisdom on the subject. Be that as it may, I would be interested to learn about the properties of such objects. As an example: if one posits a MBH with (say) the mass of Phobos (vital statistics: 22.2 Km diameter; mass: 1.08 x 10*16 Kg) how small would the event horizon be, for example? Also, in view of the gravitational tides, how near would a person be able to approach such a collapsed object without risk to life and limb? An inch? A metre? Half a furlong? I must admit that my maths isn't all that good at present - although I…

there is a star say 60 light years from us. a day comes say when it expands into a monstrous red giant and we note it on earth. when do you expect the event to have occurred on a time scale on that star: (a)60 years earlier or (b)at the time we observed it on earth....if anyone feels it as (a) then let me know how we cannot even perceive it's size increase......ie., in the sky, it's size should increase so how can we not observe it??

at the centre of the galaxy there is a super massive black hole I think he called on the tv but anyway if that's so does that mean at some point in time there was a super massive sun at the centre of our galaxy driving it in an orbit similar to a solar system only with all the solar systems and all the stars orbiting the super massive sun whilst the planets orbited the smaller suns like our own sun? if so is it not possible that countless planets possible containing plenty of life or better yet intelligent life could have been lost to this deadly natural disaster?

Dateline January 10, 2013 From: http://www.dailygalaxy.com/my_weblog/2013/01/-the-new-physics-model-of-dark-energy-nixed.html The title of this article promises an interesting discovery, but the body of the article fails to explain either what or why something may be nixed. Is this article just hot air?

Supposedly if black holes rotate, they will deform. However, this implies that each point on the even horizon is subject to inertia in the vector form, but if a black hole we see is merely the residing space within the event horizon, how is it that space itself would "bulge out"? How exactly do you transfer centripetal force to the fabric of space that would cause the event horizon to stretch out?

In what circumstances does an orbit become a hyperbolic trajectory and vice-versa? How do you actually change x^2+y^2=1 to x^2-y^2=1?

Hey what will happen to the universe if. If the universe density is less than critical density what will happen? If the universe density is equal to critical density what will happen? If the universe density is greater than critical density what will happen?

I am getting a conclusion/result in my theoretical work that the velocity of the light is increased by three(3) times from the beginning of this universe. Is there any such experimental trails showing the velocity of light is increasing or decreasing from the time of beginning to the present time? If any such trails are there then I can proceed with my theory to substantiate the theoretical proof or back ground.

1. Simple Model of Terrestrial-Planetary Structure Advanced Computer Simulations of Planetary Structures give the relationship, between Planet Radius vs. Planet Mass, for Terrestrial Planets*. For Terrestrial Planets, of sufficiently small Planetary Mass (M [math]\leq 10 \; M_{\oplus}[/math]), this result can be linearly approximated accurately. For such Rocky Worlds, of Earth-like Composition, the Average Bulk Density ([math]\rho[/math]) increases nearly linearly with Surface Gravity (g): [math]\rho = \rho_{0} + k \times g[/math] (eq. 1) where, using Earth-normalized units: [math]\rho_{0} \approx 0.536[/math] [ 2.96 g cm-3 ] [math]k \approx 0.464[/math]…

First and foremost, I am NOT a scientist or math person. I just watch science stuff on TV. The reason I even have these questions is because I was day dreaming and ended up on a logic path that singularities orbit each other at the speed of light or faster and thus travel back through time. DERP 1) I have the understanding that a black hole has a singularity at the center which is a massive object of infinite density. Does this mean that the singularity has no measurable size? I just assumed that it has no size I didn't see that on TV or anything. 2) IF a singularity has no size, then when we talk about a black hole being supermassive or large, we're only talking…

How does the curvature of space cause a photon to permanently change its path? All of the diagrams of space curving around a mass seem tp start with a rectangular grid then pull the grid down around a mass. The line that dips comes back up to realign with the original line. So why does the light lensing work?