Astronomy and Cosmology

The further away a receding galaxy is from us the faster it recedes. Is the increasing rate of recession with distance due to spacetime curvature; much like, analogously, when you see the sun setting...it apparently 'drops' quicker towards the horizon? I can't get my head around why the recession velocity increases with distance. I have no problem understanding expansion itself from any given point.

Ok, serious question from layman. If the universe is expanding... then why aren't we expanding along with it? Are only galaxies expanding? Why not all areas of space... which would include the space our atoms and cells take up. Thanks in advance!

How can we be certain about the mass of the universe, when only recently the Chandra observatory found a halo of gas surrounding our own Milky way? Although the mass is unknown, it is huge: the estimates range between the mass of 10 and 60 billion suns (comparison: the milky way itself contains between 100 and 400 billion stars). That's a lot of mass we hadn't noticed until now. And related, have we now found some of the missing dark matter? Why are we trying to invent new science to explain some missing mass in the universe, when it might just be thinly dispersed around the galaxies? I read this as: we just found out that our galaxy is perhaps up to 20% he…

Tidal Habitable Zone http://www.astrobio....-habitable-zone "The research was funded by NASA". "Astronomers searching for Earth like planets often focus on the 'habitable zone' around stars – where the heat from the star is at the perfect level for liquid water to exist. New calculations indicate that planets close to their parent stars could experience tidal forces that limit the habitable zone and change the criteria habitable planets". With regards to Mars. As is out of the Habitable Zone, how come that it had a liquid water??? In this articale it is stated: "The new calculations have implications for planets previ…

NASA Finds water on the Moon How the water had been delivered??? http://www.greenmuze.com/nature/water/1819-nasa-finds-moon-water.html "NASA has confirmed that there are'significant' quantities of water on the Moon, based on the results of their LCROSS satellite mission that crashed a rocket booster and then a spacecraft into the Cabeuscrater at the Moon's south pole." Howit had been delivered? Wiki: http://en.wikipedia....iki/Lunar_water "Water may have been delivered to the Moon over geological timescales by the regular bombardment of water-bearing comets, asteroids and meteoroids [9]or continuously produced in situ by the h…

As a direct outcome from a message which had been forwarded by Airbrush http://www.sciencefo...__fromsearch__1 I would like to verify the source of energy which generates the magnetic field in a star. Therefore, let's look on the Earth magnetic field and try to verify the energy source of this field. Earth's magnetic field http://en.wikipedia.org/wiki/Earth's_magnetic_field "Earth's magnetic field (also known as the geomagnetic field) isthe magnetic field that extends from the Earth's inner core to where it meets the solar wind,a stream of energetic particles emanating from the Sun Unlike the field of a bar magnet, Earth'sfield c…

Hi everyone! Yeah, I am a new guy with some burning questions that need member brainstorming. I am writing a script requiring me get knowledge of a plausible way for a wormhole to form. Wormholes are so cliched in scfi writing that it is embarrassing to even mention that I want to use this dusty literary excuse to get my crew across the galaxy so they can be "lost". But my research and emails with an astrophysicist have shed some light on the possibility of the WH forming in a Kerr Black Hole when the singularity is "ring" shaped. I understand that if a spaceship would enter the ergosphere of the KBH (and survive gravitational drag forces) then you could pass…

Spherical gas cloud gravitational binding energy [math]U = -\frac{2 G M^2}{5 R}[/math] Cloud thermal energy [math]E = \frac{3}{2}N k_B T[/math] Hydrostatic equilibrium (one-zone approximation) [math]\frac{dP}{dr} = - \rho g[/math] [math]\frac{P}{R} \approx \frac{M}{V} \frac{G M}{R^2}[/math] [math]P = \frac{2}{3} \frac{E}{V}[/math] [math]E \approx \frac{3 G M^2}{2 R}[/math] Force-bound, energy-un-bound, gas ??? [math]\frac{2}{5} \times \frac{G M^2}{R} < E < \frac{3}{2} \times \frac{G M^2}{R}[/math] How could a gas be energetically unbound, yet unable to overcome (gravity) forces involved ?? Inexpertly, the HSE force equation is…

Hi all I understand the solar system orbits around the galactic center and the Moon orbits around the Earth, I also understand the central bodies are not "dragging" the orbiting bodies in any sense and they simply maintain the orbit through the gravitational force, according to our current knowledge. As th example I was given previously by astronomers of a merry-go-round in a playground: as you go around it there is a outward "centrifugal" force which is trying to throw you off; the only reason you don't go flying off is because you are holding onto it. Similarly, with the Earth and the Sun, the Sun's gravity holds the Earth in place as it orbits around and ensu…

No oxygen yet for fire, matter too dense for sound waves. No photons yet for light. When did it officially become a bang? If an observer were observing the phenomenon from a distance, what would he see, hear? would he just see a steady growing sphere that starts as a dim, almost invisible point, and grows to a larger dim sphere, then a larger still only slightly brighter sphere as photon creation prevails, then a pretty significant sized sphere with subatomic particles creating more matter, more occurrences of fussion, and this more photons and a brighter, larger sphere? How many seconds, minutes, or years have to pass before enough fussion reactions have occurred to…

Okay so my theory on time travel is; when approaching the event horizon of a black hole( if you can even make it that far without whatever space craft your traveling in being stretched to it's absolute limit then being torn apart and swallowed) time seems to slow down untill it eventually almost seems to stop, but in reality, in the event horizon times seems to move at normal speed inside of it.But, on the outside looking in it looks as if your not moving at all. The laws of space time break down at the event horizon breaks down becuase there virtually is none. So, when you got back to earth you'd be in the future because you were basically in a place where time stopped o…

The binding energy per nucleon of Lithium is ~2MeV greater than for Helium. And, observations show that Lithium is scarce. Do these facts imply, that when primordial fusion was occurring, the ambient temperature was <2MeV (so that the "energy hill" from Helium to Lithium was not crossable)? The binding energy of Deuterium, the first step for all future fusion, is ~2MeV per nucleon. "Naively", Deuterium would begin to be stable, when the ambient temperature dropped below kT ~ 2MeV. Qualitatively, all the "naive numbers" point to ~2MeV as the relevant temperature value. Now, 2MeV ~ 20e9 K. And, if primordial fusion occurred at giga-Kelvin temperatures, then all…

Hi good people, I need help on this mater: Well, I belive in the Big Bang theory with the exception of "singularity"(as Jeff says), so, at the begining "this" wasnt a piece of matter highly dense!....is just not possible!!!....I do believe in more than one Big Bang occured!!!....I believe each Galaxy had its own Big Bang!!! So, please, somebody with more knowledge than me about this mater, explain to me if it is possible and if not, why?......Thank you very much advanced.... best regards Joao Gouveia International Analyst Programmer

As stars age, their rotation rate declines, [math]\omega \propto t^{-1/2}[/math], cp. 'gyrochronology'. Meanwhile, their luminosity increases, comparably. Could there be a connection, between spin down, and brightening up ?

I'm 14 years old and am interested in cosmology. I've read the stickies but didn't really understand them. Can someone give me some help?

Hello everyone, I am new to this forum and honestly I have just began to study Physics. I had never really found it interesting until recently. So I am really new to all of this stuff. I hope I do not sound like a complete idiot, but if I do feel free to tell me. I am just here to learn. My question is this, I have been led to believe that the universe started as a singularity. After the big bang the universe started expanding rapidly. I have also learned that nothing can travel faster than the speed of light. Therefore the universe should not have been able to expand faster than the speed of light. It has been said that the universe is about 14.6 Billion years old. …

how does/much or does it even; the graviton interact with the higgs field?

Is the sun hollow? Also this was said to me and was wondering if it was true. " Certain scientist believe that it receives power from "galactic currents" and that is how it is powered. The Sun is relatively cold inside, unlike popular belief from thousands of years."

A physics professor at the university of Waterloo has a hypothesis that the universe evolves and has natural selection through black holes. Where a new universe begins. Personally I really like the idea, actually had though of it myself then I saw it on through the wormhole with Morgan Freeman. I felt compelled to email Mr. Smolin, no reply but i'm sure he is a busy man and probably thinks i'm just a nut lol. Anyways I really like the concept of a multiverse and had pondered if black holes could give birth to new universes as well. What do you think about all this? here is a link - http://evodevouniverse.com/wiki/index.php/Cosmological_natural_selectio…

Employing the online exoplanets.org plotter, i played around, looking for parameters that distinguish Hot Jupiters (HJ) from "normal" planets. HJs hug their central stars; they have small orbital radii, and short orbital periods. So, i used "orbital period" on the X-axis of the plotter. Then i tried various other parameters, for the Y-axis. Inexpertly, one parameter does distinguish HJs from conventional worlds. That parameter is "spin-orbit misalignment" (SOMA). Unlike "normal" worlds, which tend to orbit in the equatorial plane of their host stars, the SOMA of HJs spans the range, from [math]-180^{\circ} < \lambda < +180^{\circ}[/math]. Inexpertly, HJs, and…

Astronomers claim to have discovered a giant cloud of gas surrounding the milky way, which is essentially invisible and was only seen by X-ray light being absorbed by charged oxygen atoms around the milky way. They claim that most galaxies could be surrounded by this "invisible" gas cloud. If this does answer the missing baryon problem, then does this mean dark matter can be entirely forgotten about? The article: http://www.space.com/17734-milky-way-galaxy-giant-gas-halo.html

Humans can measure subtle gravity distortions, over earth's surface ("free-air anomalies"). If Gravity-Waves would distort earth, and hence its gravity field; and if humans can measure such anomalies; then perhaps earth itself can be employed, as a gigantic GW detector ??

Interesting paper by physicist Bruno Deiss where he proposes a solution to cosmological constant problem. http://arxiv.org/pdf/1209.5386v1.pdf Problem: Vacuum fluctuations of quantum mechanics could account for the so-called dark energy which is causing the expansion of the universe to accelerate. But calculations say vacuum fluctuations are some 100 orders of magnitude too large. Deiss Solution: Only virtual photons and maybe the lightest virtual neutrinos contribute gravitational effects - hence dark energy. In his model, all the other virtual particles in vacuum fluctuations do not contribute gravitationally. Only particles within a limited energy range…

It might be a completely random and senseless idea but i would throw it to all who would be interested to contribute their valuable thoughts. Could it be that as a black hole continuously keeps absorbing matter from all around it and compresses matter to such density that it nears its point where matter can no longer be compressed, as the black hole keeps absorbing matter it can not contain the matter and starts to spit out the excess matter and energy turning into a quasar, further as the dead star finally reach its pinnacle of absorption and density all this time continuously being opposed by the atoms force outwards counteracting the compression force. Now it fina…

Before I go any farther, I just want to make it clear that I am NOT a creationist, I NEVER have been a creationist, and I NEVER will be a creationist. I despise creationism. I know and believe that the Earth is ~4.2 billion years old. Okay, to my point. I was watching an episode of the Atheist Experience the other day, and some moronic creationist caller started saying that he believes that the fact that the moon has so little dust on its surface 'proves' that the Earth is less than 10 000 years old. Obviously this is complete nonsense, but I confess that I was slightly taken aback, because it seems like a fairly valid argument when taken at face value. Can someone ex…