cosmology

We are familiar with the idea that mass and energy are equivalent from the famous equation E= mc2. If mass and energy are one and the same, why do we need two different forces- gravitational and electromagnetic? As photons ‘aggregate’ into matter, the resultant decrease in the number of ‘free...

The new series Curiosity is just wrapping up. It's pretty good. This first episode is titled Did God Create the Universe. They've been talking about how the net energy of the universe is zero, so basically nothing came into existence, so what role is there for god (I probably did a poor job...

That's my question. :)

You know, Cosmology isn't my field. (Though sometimes I wonder if I should change that...) I have been thinking about what the observational differences between the universe expanding because of actual momentum difference between ourselves and distant cosmological objects, and the universe...

I watched my first "Through the Wormhole" episode last night on time travel. What do others think of the series? I was underwhelmed. Pizzas and cartoonish figures with hammers, and a whole lot of "If this were true, then that would be true and time travel might be possible," etc. Is it worth...

This has, almost surely, been answered somewhere in thei forum in the last two years, but as everyone kno0ws, the noise in cosmology and astrphysics is abnormally high, and so I'd like to seek a specific answer from our panel of experts. For those who don't know about it already, the Cassiopeia...

What is the age of the universe? That looks like a simple, straight-forward question, the same in form as 'what is the age of that tree?', and very similar to 'what is the mass of the Sun?' But is it? This thread is an exploration of this seemingly simple question. It was inspired by JREF...

This thread more or less instantly got derailed into a discussion of the Kalām cosmological argument. The argument—as I understand it—goes basically: 1. No infinite set can exist in the physical world. 2. Therefore, the universe cannot have existed forever. 3. Therefore, the universe must...

There are approximately 300 billion stars in our own galaxy. A handful of these might turn out to be within range of heroic future human efforts to reach them, via centuries-long one-way colony ship voyages. However, any ongoing process of leaping from star to star across our galaxy appears...

Warning: This is wild speculation from someone who probably doesn't know what he's talking about. Please link me to any resources that would set me straight. :) Cliffs Notes: Could the possibility of a fundamental resolution to the universe explain dark matter/energy? Something about the...

Here is a Quote from Paul Steinhardt's and Neil Turok's book Endless Universe: Some months ago I was confronted by a barrage of arguments against my silly comments along these lines. I was actually told that my lack of understanding was "stupid"! It's interesting that a couple of fairly...

Hello. A good friend of mine is trying to convince me of this Grand Unification theory put forward by Nassim Haramein. The idea is that the universe is a 3D holographic fractal going inifinitely both ways (as fractals do). Our observable universe is the interiour of a big black hole (a...

A lot of people don't seem to like the idea of black holes. Understandable if you happen to run into one, but not if you simply wish to challenge the general validity of the idea. But whether you like the idea or not, it seems only reasonable that one should actually know what a black hole is...

So the universe is expanding. Space is still expanding as a result of the Big Bang and it is slowly being being accelerated apart by something currently termed Dark Energy. As a layperson with only rudimentary basic college physics, I have no real idea what "space" really is. What is it? A...

Scientific American's cover article this month posits an idea that may bypass the perplexing notion of dark energy: http://www.sciam.com/article.cfm?id=does-dark-energy-exist Dark energy being hypothesized as an explanation for the acceleration of the universe's expansion, as a result of the...

Just a question for any physicists or physics aficionados. What are the current theories of what constitutes dark matter? I keep reading articles mentioning how mysterious it is and how its producing unexpected observations in cosmology but hardly a mention of what physicists think it might be.

A question for those who know a lot more about physics, cosmology and philosophy than I do. I'm engaged in a discussion on another forum, and the topic has drifted to the idea of causality. My erstwhile opponent (who is a religious moderate with fundamental leanings, if that makes any sense -...

I was having a conversation with amb about Fermi's Paradox, and it occurred to me that it would be useful to be able to point to a list of requirements that are prerequisites for intelligent life evolving. I am attracted by the arguments for assuming that evolution of intelligent life is...

Hey, I was reading Peebles, "Principles of Physical Cosmology", 1993. On page 139, in a section talking about "Blackbody Radiation in an Expanding Universe" he says: What? No global energy conservation in general relativity? How can that be? :confused: Say it isn't so! Can anyone clear...

"How do you know that the redshift is correctly measuring time and distance?" That is a quote from a recent post by JEROME DA GNOME. In a subsequent post, he clarified his question by making an explicit reference to "Hubble's law", and I offered to start a new thread on the topic, introducing...

Is it possible to write a concise description of the Big Bang Theory? Of the general class of ΛCDM cosmological models (leaving the values of the parameters, including uncertainties, to a separate table)? Can this be done without the need for lots of links? Why am I asking this? Because a...

I've started this thread to avoid the Quarks, [OIII], neutron stars, black holes OK; CDM not OK - Huh? thread getting bogged down. Of course the nature of the observational evidence, and the analysis that takes observations and concludes 'here be (lots and lots of) CDM' is relevant to that...

The title says it all. BeAChooser has been a prolific poster in several threads in this, the Science, Mathematics, Medicine, and Technology section. Along the way, he has been asked quite a few questions that are directly relevant to the ideas, proposals, views, and propositions that he has...

I just read a neat article in the New York Times about an experiment that claims to be detecting dark matter that the earth is traveling through. According to the times, the experiment is much in the minority, but nonetheless legit, as well as quite interesting. Here's the times article...

Since a large amount of Arp's ejected QSOs theory rests on the idea that Narlikar somehow said that general relativity has a solution which allows for a quasi-steady state universe and objects that aquire mass and have an intrinsic redshift: I have to ask, would not this show up in all sorts of...

Download NGC 253, a spiral galaxy in the constellation Sculptor, thought to be nine million light years distant, from IPOD Astronomy Picture of the day, trim the image to 1359 x 1037 pixels centered on the brightest part of the galaxy, and extending as far as a cluster of emission nebulae, the...

Hey, anyone have any opinions on the "Hypatia" theory? See website here: http://quasars.org/hypatia/hypatia.htm And techical paper here: http://arxiv.org/abs/astro-ph/0210052 Apparently, Hypatia is the 5-d sphere that our universe is a part of. Supposedly, this 5-d sphere interpretation...

"Most photons in the universe belong to the cosmic background radiation that survives from the big bang. Their total number remains almost constant. The entropy per unit (call it s) equals 4/3T times the thermal energy aT4 per unit volume, where T is temperature and a the radiation energy...

This press release prompted me to begin a new thread. I'd come across several others in a cursory search of this sub-forum on the same topic, but they each appeared to be bogged down by tangental banter. I'd like to respectfully request that all interested participants stay on topic here...

Has any one read Mark Kidger's recent book "COSMOLOGICAL ENIGMAS: Pulsars, Quasars, and other Deep-Space Questions" ? Science News covered his book in the "Books" section recently, and I'm curious what readers think about it.