Astronomy and Cosmology

I understand that these black holes would be smaller and would have little effect even going through the Earth. I am curious why it would not effect Earth very much and yet leave a mark if passing through a star. Also I am curious about different ideas of how they were formed (if they even do exist). From my understanding is that they are not normal black holes from supernovae but from higher density at certain points towards the begining of the universe. If they do exist what would it mean for us? Would it help prove string theory? Thanks

As a star collapses into a black hole would it's spin rate increase as it gets smaller? If so is it possible that this spin is what keeps a black hole from collapsing into a one dimensional Point? Over eons wouldn't the spin of a black hole slow down due to friction of it's magnetic field? If so could there be a point in time when the black holes spin can no longer keep it from collapsing further and the black hole would completely vanish from our universe, even gravitationally? My thinking is that at various stages different forces keep a star from collapsing further but as each of these forces is overwhelmed by gravity the mass becomes ever more conce…

Here lately I've grown quite fond of the idea, of the possibility that dark matter may be the quantum particle of nothing itself; existing within a sea of seething and expanding energies. The energies would have to flow, or dialate around the nothing paricle and thus cause a surface tension effect. As with everything else the nothing particles would flow in the path of least resistance and eventually "pool" within the resevoirs of time dialations. I could imagine an effect that would explain the entropy and structure of outerspace, The universal constant, and the "webb" like appearence that we see aound the galaxies. I would imagine that vast amounts of en…

Hi What is time? Some say it is just measure of movement or an aggregation of events. Time is not a constant and I would like you guys to put forward your own ideas on the topic before adding my peace to the story. Alan

Hi, new member here. I am not a scientist, so please do not assume for one moment that I have any idea that I know what I am talking about. I am now in my 50s. I recall that when I was going through High School and briefly looked at the history of astronomy there was some point in time, be it classical, medieval, or earlier, when one school of scientific belief thought that the universe was not primarily empty space. That is to say it was believed that the spaces between the planets, moons, stars and so forth was filled with some kind of undetectable substance or solution. The problem is that I cannot recall what that undetectable substance or solution was ca…

i understand, that the detection of (partial) polarization, in CMB photons, by the WMAP, implies a high column density, of (ions &) electrons, along the LOS to earth. So, the conclusion has been reached, that Reionization "must" have occurred early (z~(30-10)) so as to force CMB photons to propagate through hundreds of millions of years more ionized plasma, as compared to Quasar spectra, which date Reionization to later epochs (z~6). Column density is the (integrated) product of number density times path length. Would a higher baryon density ([math]\Omega_B \rightarrow 1[/math]) admit a lower Reionization redshift, i.e. shorter path length, so reconciling WMAP t…

core-collapse SNII spray everything in (their) sight with neutrons, thereby neutron-enriching elements, far heavier than the iron peak elements. So, could cc SNII create Deuterium, by neutron-enriching hydrogen (the most abundant element in and near them) ? According to A Question and Answer Guide to Astronomy by Pierre-Yves Bely, Carol Christian, Jean-René Roy; the oldest known stars, in Globular Clusters, are enriched in heavy elements, implying that they formed, from intergalactic gas, already enriched, by an earlier generation of primeval stars, of immense mass & luminosity, which reionized the intergalactic medium. If primeval stars processed primordial …

The equations for Fluid Dynamics, on static grids, are well known, e.g. mass continuity: [math]\frac{\partial \rho}{\partial t} + \vec{\nabla} \circ \left( \rho \vec{v} \right) = 0[/math] Those equations must (?) remain the same, on expanding grids, for comoving quantities. For example, the amount of mass within a comoving cell (derivative of comoving density) can only change, by (net) mass flow into / out of the same cell, from surrounding cells, which (net) flow is measured by the divergence. If you measured all distances with an expanding ruler, then you would never notice that your fluids were evolving on an expanding grid. The only "clue" you might get…

Hello, I am currently studying the Circular Restricted Three-Body Problem and I am struggling to find some resolved exercises examples. Can anyone point me to a good book with some resolved examples or a resource I can download? I found a few good ones for the two-body problem when I was studying it and they were very useful for me to consolidate my knowledge. Thank you very much.

i understand, from some slides prepared & published by Prof. Yicheng Guo (U.MA), that during early epochs (z~5-1), the fraction of stars residing in well-formed Elliptical galaxies increased from negligible to half; and that by that epoch (z~1), emerging Ellipticals were "born" being about 1Kpc across. At earlier epochs, Irregular galaxies were the most common. i conclude from those facts, that clumpy cloud-like Irregular galaxies (Irr-1) gave rise to both Elliptical, and disky Spiral, galaxies, during early epochs (z~5-1). Those collapsing cloud-like clumps generated compact Elliptical (cE) galaxies, ~1Kpc, i.e. about as big as a Bulge in a disk galaxy. Parsim…

I was watching an episode of "Wonders of the Universe", or something like that, on the Science Channel. As I recall Brian described the universe far into the future, in very deep time, after all the stars have burned out as black dwarfs, and even after all black holes have evaporated. In fact, all matter will have evaporated, and all that will remain is something like dead photons. I am not clear on this. What will remain? Do photons die, or lose their energy, so they are dark, and yet they still exist? How can anything have no mass and no energy, and yet exist?

When observing galaxies, astronomers are able to measure their relative velocity to us. How do they measure the eventual lateral velocity when the galaxy motion is not directly aligned with us?

The degree-scale anisotropies observed on the CMB (few parts per million) at redshift (z~1000) correspond to volumes of space, at present epoch (z~0), hundreds of Mpc across. Please ponder, that the CMB anisotropies are a degree across, at (z~1000); in their immediate foreground (z~10), cosmically almost as far away, proto-galaxies are tens of thousands of times smaller, only tenths of arc-seconds across. That's like a coin on a football field, as compared to the entire stadium; or a transiting exoplanet, as compared to its star. Whatever were the "blobs" which generated the CMB anisotropies, they have expanded today into vast volumes of space, larger than the sc…

i learned about the "Dn-sigma" & "Holmberg" relations from Galaxy Formation & Evolution by Mo, van den Bosch, and White (p.271,718):

So, the zero value Higgs field has energy. Is it an energy that is reachable simply by temperature reduction? Could a ferrous asteroid fall low enough in temperature to be accelerated by a magnetic field to the speed of light?

OOPS -- Lyman-alpha forest "clouds" are large (~1Mly) (omitted baryon mass fraction) According to Mo & van den Bosch' Galaxy Formation & Evolution, from direct observations, Lyman-alpha forest "clouds" are large (~1Mly). "Clouds" cluster, and dis-cluster, on larger scales (~100Mly). Inexpertly, "clouds" are fully ionized for column densities <1014cm-2; strongly ionized for column densities <1018cm-2. "Clouds" seem associated with the peripheries of galactic structures. Separately, DLAs are weakly ionized for column densities of ~1019cm-2; and increasingly neutral for column densities >1020cm-2. DLAs seem associated with emerging spiral galaxy disks.…

I wait for support in pdf I show experiment build and new very simply tool a) desk b) laser c) 20 small mirrors ( please read step by step ) Micelson - Morley eperiment is very important point //// if You not accept yellow table in first link not read more You need read about M-M experiment in any book or use my wiki link yellow table end 1 Earth = Rocket 2 back to my link - without this I can't help You (please click file and save pdf - if any problem with open pdf I can sent by e- mail ) Part 1 start https://docs.google.com/open?id=0Bwm...kQ1ZE5GUE1MejQ Part 2 applications and brightness https:/…

If a large asteroid impacted the moon (I'm thinking of one of the recent ones that are often touted as earth killers, that pass near the earth) what would it mean for us on the Earth? This wiki article seems to say even a small one would have a significant effect on the Earth. http://en.wikipedia.org/wiki/Giordano_Bruno_(crater)

I'm not a specialist in cosmology so i won't be surprised if most of this is incorrect. Everything we can see, in the universe, travels from point A to B, in waves. So i know when i look at the sun, I'm seeing it how it was 8 minutes ago. But when we look through a powerful telescope we can see nebula's and galaxies further away from us in space, whose waves are just arriving from a long trip through space. And just like the sun we can observe them how they once looked. But since space is expanding we must also take into consideration that the light took longer because new space was forming as it traveled. Making it cover more distance but also having more distance t…

Einstein's GR is a theory without torsion. A gravitational theory with torsion is the Einstein-Cartan-theory. This theory predicts that a particle with spin causing torqued spacetime, but only on microscopic scales. What would happen if the spacetime is torqued on macroscopic scales? Is it possible to induce torsion of spacetime on macroscopic scales? If yes, how it can be realized?

Visible light, I presume, is a photon product. And since photons have no mass or charge, how are they affected by gravity? Black holes don't allow photons to escape, and light is "curved" when passing a large body toward Earth from a distant star, etc. So how can a mass-less unit be affected by gravitational pull?

General relativity tells us that there is no universal time. It all depends on your frame of reference and velocity relative to other things. So how can it be that time "began" at the Big Bang? - which is the conventional viewpoint.

I was watching Stephen Hawkings "Into the Universe" the episode about time travel. He said travel into the past is unlikely because of the "Grandfather Paradox", and using wormholes is also unlikely because of "feedback". However the most likely option is traveling at such a high speed that time dilation becomes a major factor. But traveling at such high speeds, like 90% light speed or higher, seems too dangerous. How do you dodge a pebble when you are traveling so fast? Also the faster you are moving, the more massive your spaceship is, so the more energy it takes to make any change in velocity. It seems impossible to fly around objects, which will probably destroy…

If the Sun is redder at sunrise and sunset due to passing through more atmosphere would a planet with 10x the atmosphere of the earth but with the same composition make the sun appear redder?

Is this related to light losing energy in a warm/cold atmosphere?