Astronomy and Cosmology

I read somewhere here (IIRC, I tried to search it but the search didn't work for some reason) that light intensity at astronomical distances stops falling off at the expected rate (I think it would be inverse squared combined with the redshift etc.) If I didn't dream this does anyone have an explanation or link?

a NASA press conference is scheduled for Monday 21 August (in about 4 days) to announce the first observations confirming that Dark Matter is real substance and not just a modified gravity effect Here are some pretty nice pictures. It is PDF of a talk Maxim Markevitch gave, scroll down to see the pictures. http://cxc.harvard.edu/symposium_2005/proceedings/files/markevitch_maxim.pdf the pictures show the two clusters of galaxies colliding, and the very hot ball of gas (ordinary matter) and then they show the LENSING BACKGROUND mapping the levelcurves of the dark matter density to show that the dark matter has passed through----and so has been spatially sepa…

Just something that I have been pondering for a while. Is it plausible that the big bang could be a localized phenomenon? Assumptions. 1)The universe is larger than we can imagine. 2)Gravity caused by the convergence of countless galaxies can create a very large unstable mass. (I don't know how this works so I'll ask below) 3)Big Crunches happen on a localized basis. 4)The unstable mass reaches it's critical stage and explodes. Existing galaxies in the region are pushed away if not destroyed. However, the event is localized. Does this sound plausible? Can Big Bangs be local phenomenon? It would explain the existence of galaxies/stars older than current sc…

I just received the latest copy of New Scientist and they had an article on the cyclic universe model (my favorite model). What I want to know is the percentage of scientists who believe in that model vs the other models. I've been reading about branes that collide every trillion years too and got to wondering about who believes in what.... Thanks Bettina

A space telescope scheduled for launch in 2007 will be sensitive enough to detect theoretical miniature black holes lurking within our solar system, scientists say. By doing so, it could test an exotic five-dimensional theory of gravity that competes with Albert Einstein's General Theory of Relativity. That is, of course, if the tiny black holes actually exist. Braneworld black holes are not the only bizarre things out there. Vote for the strangest. The idea, recently detailed online in the journal Physical Review D, is being proposed by Charles Keeton, a physicist at Rutgers University in New Jersey, and Arlie Petters of Duke University in North Carolina. …

this is a good general introduction to the CNB (cosmic neutrino background) by a couple of people at Dartmouth http://arxiv.org/abs/astro-ph/0608303 Anisotropy of the Cosmic Neutrino Background Ryan J. Michney, Robert R. Caldwell 5 pages, 2 figures "The cosmic neutrino background (CNB) consists of low-energy relic neutrinos which decoupled from the cosmological fluid at a redshift z ~ 10^{10}. Despite being the second-most abundant particles in the universe, direct observation remains a distant challenge. Based on the measured neutrino mass differences, one species of neutrinos may still be relativistic with a thermal distribution characterized by the temperat…

As a Ham Radio Operator, I have always fancied the idea of a "repeater" being placed on the surface of the moon. The advantage, the way I think about it, is that you would have a "satellite" in the sky with a long "window" duration for communications with nearly half the globe "visible" at any given time. Sure, it won't always be in the sky, but the moon would sure be a good base for relay stations that would facilitate communications around the world. You wouldn't need to relay between LEO satelites (limited by their altitidute and duration of window exposure..we usually only have a 10 to 15 minute window with these things every hour or so). Radio communica…

hello yes i know under current acceptable data there has never been civilization on mars (irrespective of the mars face). but as the last time the was free flowing water on mars suffcient to support life and civilization was around 1.5 billion years. unless they had some dam fantastic build materials, four thousand for our old stone ones, and a modern building perhaps 200 if not maintained. any structures once existing on the planet would have disintigrated hundreds of millions of years ago. so how would you even begin a hunt to find if a civilization had existed. best guess i could make would be radio spectrography. a scan for areas where elements that migh…

thought this was interesting: A project aiming to create an easier way to measure cosmic distances has instead turned up surprising evidence that our large and ancient universe might be even bigger and older than previously thought. If accurate, the finding would be difficult to mesh with current thinking about how the universe evolved, one scientist said. A research team led by Alceste Bonanos at the Carnegie Institution of Washington has found that the Triangulum Galaxy, also known as M33, is about 15 percent farther away from our own Milky Way than previously calculated. The finding, which will be detailed in an upcoming issue of Astrophysical Journal, …

Hey all, Tomorrow, I'm heading off to Space School UK up at Leicester University. It looks absolutely amazing. Its designed for year GCSE and A-Level students to learn more about well... space. I'm gonna get talks about current and future missions to other planets including the planned manned mission to Mars and the Moon. We are even getting a demonstration of experiments in zero gravity by the ESA student parabolic flight team! Not only that, we are going to the National Space Centre along with another observatory. It looks amazing! Even having a competition to see who builds the best rocket! Sorry I'm bragging all this but I am just so excited! I even got a schola…

In Chladni figures on a circular plate, material accumulates at the nodes which can take the form of concentric circles. Couldn’t a similar process have occurred in the proto-planetary disc of gas & dust ?. Vibrations from a slowly rotating, ( & precessing ?), sun sending out waves into the proto-planetary disc. This would create nodes where material would accumulate as in Chladni figures. These concentric nodes would seed planet formation and become the orbits of the planets. This could explain the geometric pattern of orbits in the Titus-Bode "law". According to Wikipedia:- "There is no solid theoretical explanation of the Titius-Bode law, and it is not…

Pic at the URL. http://www.universetoday.com/2006/06/12/gigantic-ball-of-fire-discovered/ Wow! I guess this thing is so massive it may be seeding galaxies by the mass that it loses as it travels. Thankfully... This blew me away when I heard it. Wow!

First time I've ever seen this. I live in a chicago suburb. I was walking down the steps and I looked out the foyer window and I saw the dark red crescent moon (wish I had a friggin camera) in the west.

I found this little cosmological piece this morning. It seems a nice little logic problem if nothing else: http://www.usapatriotsamerica.com/forum/showthread.php?t=2320

Hi guys I recently heard about a celestial object (I THINK it was an asteroid, but I am not sure) passing by -- and missing -- the moon. I tried to get information about this, if it is really true, but I can't find any concrete info.. I've seen it at the news at 3 in the morning, and as you can guess, the broadcast wasn't too informative, and I was quite tired at the time, so only bits stuck to my memory. However, I failed to find anything online.. or anything concrete. So my question is: Did we really have some object missing us at last monday?? and second; and perhaps it is only me, but it seemed that the information was quieted and not really released …

This is a new one on me. Phantom energy (responsable for present day inflation) could support worm holes and lead to our universe being engulfed in a huge wormhole, before exiting the present inflationary phase. When the universe is engulfed it could be taken on a trip through space-time! Have a look at these papers. http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=FIND+t+big+trip&FORMAT=www&SEQUENCE= Any comments?

Please forgive me because I absolutely know squat on this subject... Are there any theories involving the shockwave from the big bang and time? It sounds interesting to find a way to link our present time to some other point in time after the shockwave...like some weird reverse evolution or something. Or, do scientists still belive in this shockwave? What do they say is supposed to happen? For those who've seen my other post under biology, yes, this pertains to the same story.

hi! moon is going away 4m earth!a time will come when there will be no moon revolving around earth.how strange?isint it? can any one explain what will be harmfull effects of that? i know only one that is we'll not have any tides! pls rply:-)

I know this is impossible, but if the sun were to spontaneously dissapear and no heat or any other form of energy from it remained, how long would earth be at livable temperature? Would Venus' heat drop significantly slower due to its dense atsmosphere and abundance of greenhouse gases? I heard somewhere that Jupiter gets only 1/5 of its heat from the sun. Would the planet's temperature be affected as much as it would for the other planets by the event? Sorry, I really don't know much about this... Thanks.

hello any recently publicationed material dealing with dark matter and gravitational forces, or dark matter and electromagnetic fields, put forth and worth a read. mr d

Does anyone know? I know that sailors used to use compasses to navigate but does anyone know who actually identified the field surrounding Earth? The person who found out what caused the compasses to actually work in the way they do? Thanks in advance

It's 5am and I've spent all night woundering about the shape of light. I 've decided that it COULD be a disk that when travelling forward gets an indent to it's centre making it a small cone from where the light emminates. this may explain why you cannot see a beam of light from any angle other than from the front, unless it contacts with a medium say a gass or solid object. Any thoughts??

is it just me or does dark matter (and dark energy) seem like a way of fudging a theory in order to make it work? personally the idea of some mystical dark matter keeping our galaxy together is reminiscent of the concentric circles model of the solar system, add to that the fact that the dark matter models keep on becoming more and more complex as new observations remove possible sources of dark matter. I've been starting to think that the entire problem rests on our own incorrect view of gravity, and that some other theory like modified newtonian dynamics is where the real solution lies. This also got me thinking that black holes may also be a relic of an inco…

If I have a spacecraft that has only so much conventional fuel for a conventional rocket and also has an ion engine, could I have it burn the rocket fuel off, and then continue in acceleration with the ion engine? I know that ion engines can accelerate until they run out of fuel or reach near the speed of light, and I don't see any reason why the above scenario couldn't happen... But I wanted to see what everyone else thought. Thanks in advance.

http://www.smh.com.au/news/national/friday-13th-asteroid-a-close-call/2006/07/01/1151174439124.html So on July 3 a 400 meter wide asteroid is to pass within 430,000 km of earth and another is predicted pass within 35,000 km in 2029. There's been a lot of speculation as to what would happen if such an object hit the earth. My question is...what would happen if such an object hit the moon? Given that the moon has a smaller mass and does not have an atmosphere to protect it, would the mass of such an asteroid be sufficient to change the moon's orbit, cause a large loss of mass or severly fracture the surface? Maybe we'd just get a really cool show... Thanks,…