Astronomy and Cosmology

http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2007/11/21/scicosmos121.xml&CMP=ILC-mostviewedbox I don't know what to make of this... anyone with relevant knowledge care to opine?

How can a light year = distance light travels in a year, if time stops at light speed according to relativity? Surely light could travel 2 lightyears in an instant if it wants...

SciAm article about this http://www.sciam.com/article.cfm?id=brightest-supernova-may-reignite can possibly get two supernova explosions from same star, remote possibility of three. Brightest supernova on record SN 2006gy observed last year, over 100 solar mass star. this may have left a remnant that can re-explode and may do so within a few years. If it does, should be very interesting to observe. an important mechanism here is called "pair-instability", something qualitatively different happening in the core of a star when it reaches a certain temperature threshhold (the light starts producing electron-antielectron pairs) Seems worth understanding. I for…

In general the reflecting optical telescope has a large-aperture concave mirror for gathering and focusing light from astronomical bodies. As you've known, larger the size of mirror becomes, more difficult making such mirror with sufficient accuracy. Here is an alternative method to avert such difficulty; http://hecoaustralia.fortunecity.com/telescope/reflect.htm

My friend called me up a few minutes ago ranting about how his co-worker had told him that as recently as two weeks ago a new discovery was made, in which us earthlings unearthed a separate universe and found earth like planets within it.... I don't see how this is possible, and upon scouring the net I found nothing at all... I'm just wondering if anyone else has heard something along these lines..

This is a good question for Marvin. I'm just wondering if this theory is debated at all, or if there's any solid proof. I've heard theories saying that the BB was the result of two "branes" colliding, in which case there'd have to be space and time all ready.

Hello everyone. i haven't posted here in a few months. as many of you may remember, i often asked questions of speculative pseudo-science based on my penchant for science fiction. however, i am happy to announce that i recently began reading textbooks on true science, and, as several of you had told me earlier, i would find reality a lot more interesting than warp speed and teleportation - which i do. it is liberating to learn true science, and to be unplugged from the fantasy that is called sci-fi - almost as liberating as when one realizes the truth of Natural History as opposed to what is listed in Genesis. anyway, now that the good news of my awakening to real…

I recently attended a popular science lecture at the University of Sydney. The speaker said that if, given enough time, you travelled in a straight line out into space, you would eventually arrive back where you started from as if space was circular and you had circumnavigated it. Is this remotely correct?

Hi Guys, I recently read a very interesting article about a new model of the evolution of the earth moon system, which is based on non-Newtonian physics approach. To me, this model makes a lot more sense than the tidal friction theory. Here is the link http://arxiv.org/ftp/arxiv/papers/0704/0704.0003.pdf Any comments?

Paper just came out in Science magazine identifying the source of ultra high energy cosmic rays as Active Galactic Nuclei (AGN, supermassive black holes) Excellent article on this in PHYSICS WORLD, just released today http://physicsworld.com/cws/article/news/31764 ========================== The actual technical article in Science magazine is "subscribers only" but there's a free summary Science 9 November 2007: Vol. 318. no. 5852, pp. 938 - 943 DOI: 10.1126/science.1151124 Using data collected at the Pierre Auger Observatory during the past 3.7 years, we demonstrated a correlation between the arrival directions of cosmic rays with energy above 6 x 10^…

See the rest: http://www.spitzer.caltech.edu/Media/releases/ssc2007-17/release.shtml

Why do pulsars pulse? Isn't the output beam coaxial to rotation?

Hello everyone I am reading a bit about Sumatomic particles and yesterday a thought struck me. What happens inside a black hole? As far as I know there's a lot of matter and antimatter in there. With all matter centered at the singularity the chances that, for an example, an proton and an antiproton collides would seem quite high, converting into energy. Take that scenario and replace it with a large number of particles. What do you think about this question that struck me? What goes on in there? Thanks for all the replies.

This always bugged me. It seems to me like there is a large ammount of vacuum energy in space, why can't we use it? I'm sure there are a number of ways to harness it. You could build a sealed structure in space designed not to crumple under the vacuum pressure, and drop it down to earth. Earths gravity will bring it down for you if it weighs enough. Then on earth, connect the vacuum to a pneumatic generator running backwards or something of that sorts. Why couldn't this work, I'm sure I've missed something.

The universe’s clock has neither a start nor finish, yet time is finite -- according to a New Zealand theorist. The theory, which tackles the age-old mystery of the origin of the universe, along with several other problems and paradoxes in cosmology, calls for a new take on our concept of time -- one that has more in common with the “cyclic” views of time held by ancient thinkers such as Plato, Aristotle and Leonardo da Vinci, than the Christian calendar and Bible-influenced belief in “linear” time now so deeply imbedded in modern western thinking.

If I had to put a single number down as the age of the universe, what would be the safest one as of the current consensus? EDIT: You know, this might go in "homework help." I'm putting this in a scholarship essay and I just want a safe number.

The sixth International Conference on Gravitation and Cosmology will be held December 17-21 in India. This is the next conference of this type that I know of (general relativity, gravity, cosmology). Checking out the programs at these conferences is a way to keep track of what professional cosmologists are interested in, talking about, doing research in these days. Here is the homepage http://meghnad.iucaa.ernet.in/~icgc07/index.html Here is the list of plenary speakers. http://meghnad.iucaa.ernet.in/~icgc07/sub/plenary.htm There are 21 plenary speakers listed of which SEVEN are discussing Quantum Gravity. I see that one of the seven is string. Parampreet Sin…

-------------------------------------------------------------------------------- I have to present a science fair project to my small group in science class in class Friday. It is geared toward second grade students. Any ideas like a solar system mobile or anything else that is not a book relating to the solar system?\Something "hands-on. Thanks for the help

Hey guys! A friend sent me this: http://media.armadilloaerospace.com/2007_10_21/modFreeFlight.mpg It looks AWESOME as hell. I was wondering if you heard anything about the plan to make another "X-Prize" thing with lunar landers, and if NASA is going to purchase the lander from a contractor, or keep being all secrety-hushhush and do its own projects..? Anyhoos, it's a cute movie regardless. ~moo ---- EDIT: ---- Right. Okay. Uhm.. http://www.space.com/news/071028-armadillo-aerospace-failure.html So.. yeah. This won't be it, apparantly. I should really learn to read *EVERYTHING* before being all happy. But in any case, I also found t…

Admittedly I'm a day late, but yesterday marked half a century of space exploration, which of course was the launch of Sputnik I, and was clearly a catalyst for technological developments between the Soviet Union and the US. Here's an article from PhysicsWorld (formerly know as PhysicsWeb.) http://physicsworld.com/cws/article/news/31388;jsessionid=BBD13BDC510B12517BC1D06FA2060C1D

http://rivelles.blogspot.com/2006/10/pictures-from-mars.html the tracks of the rover, Opportunity, as it approached the Victoria crater are visible from overhead, as is the rover itself (a tiny speck at the crater edge) nice shot of the crater.

Hi! I'm new here (obviously) and I'm taking an astronomy course because I needed another science course for my degree and I could use some help. I'm going to throw some questions out here and if you folks would be so kind as to answer them it would be greatly appreciated. 1. Radial motion can be revealed by spectroscopic analysis using the: A) the Doppler Effect. D) the Photoelectric Effect. B) Stefan's Law. E) Gravitational Redshift. C) Newtonian Relativity. 2. The particles which enter into chemical reactions are the atom's: A) neutrons. D) positrons. B) electrons. E) protons. C) mesons. 3. What is the resolving power of the telescope? A) the …

where did hydrogen originate from?

If one of the centauri stars exploded/imploded would it effect our solar system?

Why do galaxies take on the shape they happen to take on? What I am wondering is that if space was a vacuum, and gravity has infinite range, then galaxies of course should really respond to each other or collectively I guess to all the gravities of galaxies per say operating at once. It would seem as if this is not true. That’s not really my question though. Is it purely gravity that causes the shape of a galaxy, or is it a mix of various natural phenomena, such as gravity, electromagnetic and thermal effects operating at once? I am just wondering if you get so far from a galaxy, which I know we cant do, if you would detect no gravity really. I know that’s not at all the …