Astronomy and Cosmology

Hey everyone, I've heard that with many mechanical devices that we place into space, we first loop them around the Earth to build up velocity, allowing for them to 'rocket' out of our gravitational pull and to gain some momentum. I've also heard that light curves around gravity; since light is a form of energy, I was wondering if energy is uniformly affected by gravity as well. If so, would it be possible to slingshot a minimal amount of energy around, say, a star, and to have it 'recharge' and return to it's point of origin? This is some really sci-fi stuff, I realize, but I'm just curious if it's at all feasible. Thanks, Oddt

I was surprised to note that in this place of quality and higher learning that no one is speaking of 2012 and it’s spatial consequences or possibilities.Personally, I do not believe any of the speculations but do wonder just how advanced our forefathers were and why they would bother creating such a long term calandar. Do you consider the doomsday scenarios as bogus as I do or is there anyone who gives 2012 some serious thought? Regards DL

I was just wondering, what's preventing another big bang from happening right outside my window?

You know, just in case we ever get around to spending this unbelievably grand sum of money to pointlessly send a few families on a ten to twenty year fool's journey to a pointlessly incompatible star system a whopping several light years away. Iron rain showers in space! Well shiver me timbers.

I was told today by my physics professor that the Earth undergoes magnetic pole reversals, some of the evidence being molten rocks with magnetic properties on earth orientating themselves towards a different north pole which points towards the north pole being different in the past. He said that the current north pole is actually somewhere in Ontario Canada and within the next year will be somewhere in Siberia. While this is happening of course the south pole is moving up. I was told that this can happen without serious consequence as far as we know. Is that true? What would happen if they became completely reversed and north became south and vice versa? Would ou…

lets say there are 2 people named gracie and george, gracie is 60 light years away and (george is slow)george takes 3 years to get on a jet pack and he goes 553million miles an hour so it takes 3 years to get to gracie will 6 years pass for him and 60 years pass for her if you are right above the event horizon of a black hole no time will pass for you nomatter how fast you are going light will always trave 650 million light years for YOU are these true

After the big bang pair production resulted in (among other things) positron-electron pairs. Positrons do not decay, so they can be removed only by annihilation with electrons. Where did the surplus electrons come from?

Since all the planets move around the sun on an elipitcal plane with the exceptions of mercury (7degrees) and pluto (17) is the general solar plane even with the milkyway's galatic plane? If so, are most planetary or binary star orbits also close the same plane, or is it pretty random? Also, I read somewhere that the solar system actually dips down and comes up on a sine wave like pattern relative to the galactic plane - do we know what the mechanism and freqency of this occurance is, and if it is observed in any other orbital systems we've discovered?

As I understand it, both light and gravity dissipate at the same rate with distance from the source. So I think it would be correct to say that gravity and light fade at the same rate and disappear at the same point relative to distant objects. Does this mean that there is no possibility for either gravity or light to ever be present without the other? Or can light ever extend beyond gravitation in some other way? If not, does this mean that spacetime ends at the hubble horizon for any given point in the universe? Or is there some way that gravity, light, or some other force/phenomenon could extend beyond points where expansion and relative motion have reduced light …

formation of moon maria 3.5 - 3.0 Gya indicates time of total tide-lock to earth ??? Older maria (4.2 - 3.6 Gya?) [+3-6 billion earth-scaled years] from 'natural' planetological processes? (Source: U-of-Oregon)

According to Ivanov (2008), Note the apparent typo, in the (second?) subscript, of the above equation. Assuming, to begin with, that the authors meant to say: [math]\pi_D = k_D \pi_2^\beta[/math] then please ponder the application, of the above equation, to planetary impacts, by simplifying the notation: [math]\pi_{D} = D_{at} \left( \frac{\rho}{m} \right)^{1/3}[/math] [math]\equiv D_{at} \left( \frac{\rho}{\frac{\pi}{6} D_p^3 \rho_p} \right)^{1/3}[/math] [math]\equiv \frac{D_{at}}{D_p} \left(\frac{6}{\pi} \frac{\rho}{\rho_p} \right)^{1/3}[/math] [math]\approx 1.24 \left( \frac{D_{at}}{D_p} \right) \left( \frac{\rho}{\rho_p} \right)^…

Can the universe arise out of nothing? Quantum 'nothing' is now a boiling bubbling brew of matter popping in and out of existence, which accounts for the majority of the mass an atom has. What are the implications of this theory?

There are methods for calculating the horizon size of the cosmic microwave background. Are there similar methods for calculating the horizon size of the cosmic neutrino, gravity wave backgrounds. I suppose a simple percentage addition of (first light)/(universe age) (300,000/13,400,000,000) works if you assume that neutrino, gravity speeds are at the speed of radiation ?? Also i have heard that the limits of vacuum energy is 1000 times that of the radiation or CMB horizon. Wouldn't the gravity waves from vacuum energy expansion affect the cosmic gravity wave horizon?

This is a neat idea. What kind of materials can you get from asteroids? How would a moon elevator work and why would it use less energy than rockets, and how much less? Also, why not just send robots to mine the asteroids where they are and just bring the really valuable stuff to Earth? Is there really that much use for a lot of iron (I assume this is the main metal astroids consist of)?

Resent studies show the universe is expanding at an accelerating rate, since our solar system is part of this universe how is it that we can see this movement? Shouldn't this movement be happening to us as well? Is it the slowness of light and the age old stars we are looking at in the universe expanding, or is the theory incorrect? Its like being in a car and driving down the road, the only way you know you are moving is if your surroundings are moving. If you block out your surroundings and only see a car next to you going at same rate, it seems as though you are at a stand still. Why aren't we expanding as well? Is there a possibility that we are, and we don't even rea…

According to the National Geographic Channel documentary Naked Science -- Journey to Jupiter (TV), Ganymede, Callisto, Io, & Europa are Jupiter's "four largest moons". But, they are also the four innermost moons, yes ?? And, most basic textbooks observe that Jupiter's Moon System is much like a "mini-Star System". Thus, on the basis of this "Gas Giant analogy", the Sun's innermost planets ought to be the biggest planets. QUESTION: Could it be, that the four Terrestrial Planets are actually the biggest planets — in particular, bigger than the rocky cores of the Gas Giants ?? And, on the strength of the same said analogy, why wouldn't Jupiter poss…

I have heard Universe is expanding in accelerating speed because of Dark energy. What is Dark energy? If it is true when will Universe stop expanding? will it need any other force to slow down?

Galaxies are "anchored by a Super-Massive Black Hole" (SMBH). And, that SMBH can generate a Quasar, when it is "actively-very actively- feeding on surrounding gas". Such occurred, quite commonly, in the early universe, which was much more matter dense. Or, more recently, mergers of galaxies can funnel material into central SMBHs. Now, SMBHs are associated with "intense star formation". Thus, they are associated, and perhaps trigger, "'starburst' galaxies, forming stars at 10 to 15 times the rate we see in the Milky Way today". Such star-burst galaxies were much more common, in the early universe. For example, galaxy HUDF-JD2 "formed the bulk of its stars very ra…

Determining the thickness of Europa's ice-crust Even as the below-water height of an earth ice berg, can be determined, from its above-water height (by the ratio of 6/7ths : 1/7th); so, too, the thickness of Europa's ice-crust could be determined, by measurements, of how high that ice rides, up above the water presumably present, in the fissures, in between the ice-crust 'tectonic plates'. For example, if the water, in those fissures, was -1 km below the ice-crust surface, then the ice-crust would be ~7 km thick [modified by the actual ice density ratio, appropriate to Europa's colder climate]. Melt-water must be left inside the melt-shaft, to equalize pressur…

Quick Analogy: When a comet comes near some central star, it heats up, off-gases, producing jets, which "rocket" the body around. And, when a charge, comes near some other charge, and accelerates rapidly, it emits various radiation-reaction forces (e.g. Synchrotron, Bremsstrahlung). These scenarios are a little alike.

I am confused about what is the shape of a black hole. I hear that it is a sphere and then it is a doughnut with a hollow middle, or are these two shapes the process of a black hole, with the black hole taking the shape of a sphere and then a doughnut? Can anyone clarify this?

Gore-Tex is a material incorporating fluoropolymer membrane with micropores. The roof of the Hubert H. Humphrey Metrodome in Minneapolis is one of the largest applications of Teflon PTFE coatings on Earth, using 20 acres (81,000 m2) of the material in a double-layered, white dome, made with PTFE-coated fiberglass, that gives the stadium its distinctive appearance. The Millennium Dome in London is also substantially made of PTFE for PTFE lined ball valve

The Schwarzschild solution, whose low-mass limit is Newtonian Gravity, assumes an infinite, flat, spacetime, which is then perturbed by the addition of a spherically symmetric mass. In analogy, it assumes an infinite flat trampoline, or infinite flat rubber sheet. Now, that assumption is not inaccurate, in our current Cosmos, whose Radius of Curvature is 10s Gly's, so that space is almost flat. But, what about shortly after the Big Bang, when spacetime was highly curved ? If spacetime is cosmically closed, into a 3D hypherspherical shell, then, in the early universe, deviations of spacetime, from 'infinite & flat', could have caused deviations, from Schwarzschi…

Hello everybody. 1. Object of what minimum size can we detect in space using optical telescopes and radiolocation? (and at what distance?) 2. What resolution shall have a telescope (on a satellite) to be able to clearly discern a face of a human on earth? How far in deep space from Earth can such satellite with telescope be placed to maintain it's ability to discern human faces on earth? Let's imagine that it moves simultaneously with the Earth's rotations. Thanks in advance.

According to Black Hole Complementarity, when an observer sees another falling into a black hole, the effect that gravity has on light waves would make any observation of the person slow down, eventually stopping him before he hits the horizon. In addition, he will appear to be "stretched" across the whole horizon, his particles being hit and separated by the halves of virtual photon pairs that, since the other half is unobservable inside the horizon, have the same effect as normal photons. Meanwhile, to the one falling in, there is nothing particularly interesting about the horizon. Am I correct? Then in theory, say the person falling in is feet first. What will happ…