Astronomy and Cosmology

At least every few minutes: http://news.yahoo.com/s/space/20081103/sc_space/strangeportalconnectsearthtosun;_ylt=AhD9_RNgj1Q0N.EfOQfQYPkiANEA

Ashtekar (born 1949 in Maharashtra) is a key person in the current process of re-understanding the Big Bang. We should know about both the person and the ongoing research progress, involving many others as well, in which he plays an important role. So here are some links and random details. Here's a 1999 profile by a NYU journalism grad student (human detail: childhood, family, career-start, mentors, friends,...) http://us.rediff.com/news/1999/may/15us2.htm http://us.rediff.com/news/1999/may/15us3.htm http://us.rediff.com/news/1999/may/15us4.htm http://us.rediff.com/news/1999/may/15us5.htm Here's the CV at his website: http://www.gravity.psu.edu/people/As…

Science News of Oct. 25 reports "Galaxy clusters slide to the south". I quote the article: "Clusters of galaxies are flowing through space, seemingly under the influence of a mysterious attractive force outside the visible universe, a new study suggests. Researchers have detected what they have dubbed 'dark flow' while surveying 700 galaxy clusters [within one billion LY of Earth]. On average the clusters appeared to move at about 1,000 km/sec in a uniform direction toward a point in the southern sky." My my, it seems there is sort a hole in our baloon. We work with the Robertson-Walker metric assumptions of uniformity, and this is clearly a simple model. Hang onto…

Arch2008 has gotten confused about the standard mainstream cosmology model, and has taken to repeating over and over again a faulty argument. I've explained briefly why it's wrong and will do so here at somewhat greater length. I don't want other people to be misled by Arch and get into a similar confusion, so I want to be really clear about this. In cosmology all we have is models, which fit the data more or less well. They represent the most we know about the universe as a whole, at large scale. The current consensus model is called LCDM (sorry about the technical alphabet soup, I'll try to keep such abbreviations to a minimum). It comes in two versions spa…

We started some REALLY interesting stuff in our Classical Dynamics class - Keppler's laws (sp?). As an initial intro, our professor explained a bit about ellipses and the reason planets travel in an elliptical orbit around the sun. This was always a sort of a conceptual problem for me, tbh; I guess because i'm used to think of things in terms of simple Newtonian physics, but I always wondered about this. It seemed to me that the "most efficient" orbit is circular, because all the forces equal one another (no change in speeds, too), and I wondered why the planets are not moving that way. The professor did a good job explaining about this (let's see if I got this ri…

They say that there are thousands(or is it hundreds of thousands) of Galaxies out there and that most of them indeed are galaxies. I'm wondering how can they tell for sure if they are galaxies or not? Main reason I'm confused is this, if 1 very distant object(star/galaxy) can through gravitational lensing appear to us for example as 10 separate sources of light, etc. I guess to rephrase that, taking Lensing into consideration, how do we know which are really stars/galaxies?

It's said that the universe is expanding at such an increasing rate that its outermost areas will pass a cosmological "event horizon" that is beyond our reach. Afterwards, evidence of that part of the universe will vanish forever. Not true. I may have no evidence to present, but all you really need to do is extrapolate on a basic theory to know it might become possible to see any part of the universe beyond that supposed event horizon. Wormholes are the key -- if they exist. If they don't, other ways are sure to pop up. Such means of travel don't care if a spot in universe is not reachable by conventional means. Unless, of course, I'm wrong. Thus my re…

JPL discovered a strange anomaly in the velocities of spacecraft that used the Earth to provide a gravity boost to help the spacecraft reach their ultimate objective. An intro on the flyby anomaly, from the Planetary Society: http://www.planetary.org/news/2008/0228_Researchers_Investigate_New_Cosmic.html 28 February, 2008. A new study by researchers from the Jet Propulsion Laboratory shows that spacecrafts that swing by the Earth are subject to a small but unexplained increase in their velocity. Is an unknown physical force at work, or something far more mundane? Some exotic explanations were proposed, including General Relativity (see the above article), the Unru…

Greetings people, Some quasars are believed to be 14 billion light years from us and receding at greater than the speed of light. I still can’t rap my silly little brain around this, how are we earthling sitting out here somewhere in the universe observing light from an object that might no longer exist. The 14 billion light year distance seems impossibility to little me Please help this little tiny entity Take Care ALAN

Is it Theoretically possible to ignite certain gas giants or even create a large ball of gas in space that we could ignite to create something that might resemble a miniature sun?

it has been suggested that black-holes exist in all galaxies I disagree if black-holes do exist in the center of galaxies then why is light eminating from these galaxies ?

Could we please have a list of all known observational and/or experimental facts that prove Earth is moving? I can briefly recall the following: 1) Foucault's pendulum. How many times has it been repeated? What were the conditions? 2) Coriolis force, regarding winds and hurricanes. 3) Motion of ballistic misiles. Does anybody know details regarding the influence of Earth's rotation on the latter?

To avoid confusion agentchange, the value for omega determines the fate of the universe. An infinite universe in the contex of this value means that it expands forever. That doesn't mean that it is now infinite in size. A universe that starts as a finite space smaller than an atom and expands at a finite rate for 13.7 billion years is not going to suddenly be inifinite in size. "Is the Universe really infinite or just really big? We have observations that say that the radius of curvature of the Universe is bigger than 70 billion light years. But the observations allow for either a positive or negative curvature, and this range includes the flat Universe with infinite…

Do you believe space is finite, or do you think it's infinite? Or do you believe we don't have enough evidence to tell yet? It's a fascinating question. Next year two new satellite observatories, Planck and Herschel, are scheduled for launch---their data may help resolve this! I'm posting this on behalf of Agent. He had the excellent idea of a poll on this issue. But he neglected to include any way for science-minded people (who require scientific evidence for their belief) to take part in the poll! So to correct that, I've reformulated the poll.

Einstein Online is an amazingly informative website that the AEI (Albert Einstein Institute) started in 2006 and is still adding to. They have a section on cosmology that is the best introduction I know of not requiring a lot of math. Indeed it is math-free but still manages to be up-to-date and accurate, which is quite an accomplishment. To get there, google "einstein online spotlights cosmology". They have other sections that spotlight other topics as well, like relativity, black holes, quantum theory,... The section that spotlights cosmology has 8 articles they call basics, plus some extras that go beyond those 8 basics. I'm wondering how many other…

Everyone wants to know the shape of the universe. It's a rather interesting question. But: is there a practical application of the knowledge? If I find out that space is a sphere, what does that allow me to do besides change our textbooks?

Does anyone think that it might be possible to harness the kinetic energy of an object in orbit and change it to electrical energy? If so, could we built special staions to orbit and harvest? or could we use the moon?

I run a website for beginning astronomers, I hope you find it useful.

Aterna posted this interesting question http://www.scienceforums.net/forum/showthread.php?p=431829#post431829 BTW welcome! (she's a new member at SFN) The way I interpret it is you get to travel at a steady speed of c, in a straight line. And the question is, where do you get to? Assuming you can leave earth and travel in a straight line indefinitely (you are immortal--infinite lifetime--so there's no time limitation.) the answer depends on the standard cosmology model, currently supported by vast amounts of data and a consensus of working astronomers, but models do change so that's something to remember. the answer is a bit surprising----traveling at the sp…

The first NASA spacecraft to image and map the dynamic interactions taking place where the hot solar wind slams into the cold expanse of space is ready for launch on Sunday, Oct. 19 at 1:48 p.m. EDT. The two-year mission will begin from the Kwajalein Atoll, a part of the Marshall Islands in the Pacific Ocean. The IBEX spacecraft will conduct extremely high-altitude orbits above Earth to investigate and capture images of processes taking place at the farthest reaches of the solar system. Known as the interstellar boundary, this region marks where the solar system meets interstellar space. NASA is to webcast the the IBEX launch, you can find out more here: ht…

Severian said this very well in the context of a different subforum If you don't know the basics of standard cosmology, please ask questions. There are people at SFN who will be glad to explain things. If you want to criticize the standard picture that professional cosmologists use these days, be sure you know what you are talking about. If you want to present alternative concepts, be sure you first have an adequate appreciation of mainstream cosmology. In order to argue for your alternative you must have an accurate understanding of the mainstream picture. ========================================================================= Here's a quick way t…

All the papers are here http://lambda.gsfc.nasa.gov/product/map/current/map_bibliography.cfm

Ok, this may be totally stupid, but I was thinking that would it be possible if a planet, such as earth, could have actually formed due to a dying star? The center of our planet is molten iron that is close to the temperature of the sun, that and our relative proximity to the sun is what helps make our planet a habitat that our life form can live on. So here is my weird thought on this. What if when a star is dying , over millions or billions of years it is dying the gases surrounding it that contain dust and debris begin to accumulate and form a crust around the dying star. The star shrinks over a long period of time , the outer crust grows larger, until the surr…

This first one was actually shot during the first flyby in January and I was really stunned by the bright colors emanating from a strictly metallic surface. It reminds me a lot of granite, though closer up, the coloring surely looks much different. Do you think the coloring is accurate? Do you think that perhaps large amounts of liquid exist there, only with a much higher melting point?

http://en.wikipedia.org/wiki/Hans_Lippershey I read an article in Astronomy magazine that described how Lippershey tried to get a patent for the first telescope (Greek tele = 'far' and skopein = 'to look or see') in September-October 1608. Lippershey’s telescope could magnify a whopping three-fold. His request was turned down after it was found that lots of crude telescopes were being sold at carnivals. His was however the first actual recorded design and his patent ignited scientific curiosity in the device worldwide. Of course, Gallileo claimed to have discovered the telescope to get funds to improve them and was the first to point it at the sky. The design indirect…