How long would it take for satelite to reach mysterious dark energy?
958018
Dark Energy is a theoretical tool based on the need to explain observations of the Universe.\n\nCurrent cosmological theories are dominated by the 'Big Bang' theory. When this theory is proven wrong, then the need for Dark Energy will go away. It is theorized because the cosmologists need it to make their mathematical formulae to agree with previously accepted theories. It is like a carpenter who uses a ruler, believing it to accurately measure 1 foot. But he is not taking into account the expansion or contraction of the ruler depending on the ruler's temperature. In a small scale - the carpenter's project - such a tiny change is unimportant. But when the ruler becomes very very long, then such changes in length become unacceptable. At first, the carpenter will believe that some other factor was the reason that his measurements - taken on days with differing temperatures - produced differing lengths. But once the carpenter understand the relationship of his tool to temperature, he can take the temperature into account. \n\nCosmology is using many old tools as it tries to explain the Universe. But it is too soon to understand all the variables that are producing conflicting answers. Cosmologists make their best guess as to which tools are giving the best, most accurate, most usable answers, and then go on from there.\n\n;-D But every tool that has an unknown error or bias makes finding the truth impossible. That is why there are theories that are almost exact opposites of each other. Such theories can not both be correct. Probably they are both wrong.
15135
well, i'll answer your questions in reverse order.\n\nneptune's average distance from the sun is about 4.5 billion kilometers, or about 30 times as far out as the earth.  it has a diameter of around 50,000 kilometers, which means it's about 4 times the size of the earth.\n\nas for how long it would take - that entirely depends on what kind of spaceship you used to get there.  if you had a fictional spacecraft that could go nearly the speed of light, it would take around 3 hours.  if you used the same kind of spacecraft that the apollo missions used, you would be traveling around 25,000 MPH.  this is around 40,000 kilometers per hour, so:\n\n4.5 billion kilometers / 40,000 kilometers per hour = 112500 hours = 13 years or so.
958242
Taking the milky-way galaxy to be approx 100 000 ly across, and travelling at a realistic speed of 5 000 km/h, it would take just under 200 000 billion earth years to traverse the galaxy end to end.
491273
Right now, we're not even close to faster-than-light (or FTL) travel.  All out traveling has to be done at less than the speed of light, so most stars are farther away than we can get to.  Even at half the speed of light (which is far faster than we can travel) it would take 8 years to reach the nearest star, not counting the Sun.  (Not to mention 8 more years to get home afterward!)  Nothing can move faster than the speed of light, so our best hope is to do just like they do on Star-Trek.  The found a way to bend spacetime to get to distant stars without actually moving through normal space, which had less of a curve.  Nobody has any idea how to do that now, so we just have to keep expanding our understanding of science until we do.  Until then, I think our best bet on meeting intelligent extraterrestrial life is to hope for them to come to us!
942007
The jury is still out on this one. In until recently (the past few years) most scientists agreed with the Big Crunch theory, that the inertia of the expansion would eventually yeid to gravity, and the universe would collpase in on itself. Even Stephen Hawking believed this theory. But a few years ago. "Dark Energy" was discovered. It occupies the vast spaces between the stars and galaxies, that was originally thought to be only a vacuum. That darkmatter  is providing a "pushing out" affect. So now I would say that the majority of cosmologists believe it will expand forever.
1100180
Well that is really hard to answer, A point 13 billion light years as referenced from what? Remember that they earth is in orbit around the sun, the sun is in orbit around the galaxy, the galaxy itself is moving.\nIf we assume the universe is about 15 billion years old the universe was quite a bit smaller. So obviously the object would have been closer. But are you talking about something that is moving towards us? moving away? we need some reference point to even begin thinking about answering this question.\n\nThis is like asking "how far away was a car moving 60 miles an hour, and hour ago?" was the car coming towards us, away, moving parallel, are we in another car? how fast are we travelling?\n\nDo you see that you need to qualify your answer, in order for us to answer it.
155835
The problem is to tabulate the total mass of the Universe, a realy BIG problem.  There may be a lot of undetected dark matter in the universe that would shift calculations of the Gravitational Constant that will determine the fate of the Universe.  It is like trying to count the mushrooms in a totally blacked out cellar while blindfolded, or even much harder.  Progress is being made as the limits of the Universe are being explored by every means possible, especially by use of the human brain.
527301
Difficult to say for certain. Some possibilities include:\n\nSwallowed up as the Sun enters red giant stage\nYou will need: patience\n\nMethod: Simply wait for roughly 5,000,000,000 years. During its natural progress along the Main Sequence, the Sun will exhaust its initial reserves of hydrogen fuel and expand into a red giant star - swallowing up Mercury, Venus, Earth and Mars in the process.\n\nEarth's final resting place: Boiling red iron in the heart of the Sun.\n\nFeasibility rating: 8/10. The problem here is that current scientific theories predict the Earth will probably survive. The increasing solar wind combined with the Sun's decreasing mass will result in the Earth gradually moving out to a wider, cooler, safer orbit.\n\nEarliest feasible completion date: AD 5,000,000,000\n\nTorn a new one\nYou will need: about half as much patience\n\nMethod: Recent experimental results seem to show that the expansion of the universe is not slowing as one might imagine it would. In fact, the expansion is accelerating. It's a bit early to say with confidence why this is happening, though phrases like "dark matter" and "phantom energy" pop up pretty frequently, but anyway, it's conjectured that if the ratio w of dark energy pressure to dark energy density in the universe is negative enough (buh?), then the universe would expand, accelerating in its expansion until it was ripped apart at the seams. To quote Wikipedia's entry: "First the galaxies would be separated from each other, then gravity would be too weak to hold individual galaxies together. Approximately three months before the end, solar systems will be gravitationally unbound. In the last minutes, stars and planets will come apart, and atoms will be destroyed a fraction of a second before the end of time." Cool, eh?\n\nEarth's final resting place: HAH! If I knew that, I wouldn't need aftershave.\n\nFeasibility rating: 8/10. Likely. Assumes the Big Rip theory is correct, which it probably is, but might not be.\n\nEarliest feasible completion date: AD 20,000,000,000, assuming w = -3/2 (could vary)\n\nSource: a theory proposed by Robert R. Caldwell, Marc Kamionkowski, and Nevin N. Weinberg in February 2003. Read it here (PDF warning! Also, dense, difficult physics!). Brought to my attention by Jonah Safar and nanite.\n\nDecayed\nYou will need: all-surpassing patience\n\nMethod: If the Big Crunch doesn't happen, and the Big Rip doesn't happen either, then we come back to the third option: the Big Chill. For this, the universe will just expand, forever. The laws of thermodynamics take over. Every galaxy becomes isolated from its neighbours. All the stars burn out. Everything gets colder until it's all the same temperature. And after that, nothing ever changes in the universe. For eternity.\n\nA lot can happen in an eternity. Protons, for example, while incredibly stable, are believed to eventually decay like any other particle. So simply wait for a period of time of the order of 1,000,000,000,000,000,000,000,000,000,000,000,000 years, and roughly half of the constituent particles of Earth will have decayed into positrons and pions. If that's still too much like a planet for you, you could wait for another 1036 years, leaving only a quarter of the original Earth. Or wait even longer. Eventually there will be as little of Earth left as you wish.\n\nEarth's final resting place: Miscellaneous positrons and gamma radiation (pions decay almost instantly into gamma ray photons) scattered thinly across the entire universe.\n\nComments: It's interesting to compare this method with the one right at the top (total existence failure). What we are essentially doing here is almost exactly the same thing, only instead of expecting every particle to disappear at once, we are waiting patiently for a significant proportion of them to disappear, one at a time, over the course of an unimaginable period of time. Essenti
631597
Just one doubt about your  theory,how do you know that only one big bang has taken place as you say that a second one is coming up???And tell me how you would accelerate something to the speed of light as the mass would become infinite.\nAnd according to your theory the total energy in the universe will go on increasing.You are stuck in a viscious circle!!!
399340
Well, just taking the rough slowing of the earth's rotation of about 1 second every 60,000 years, and extrapolating out to when it will be tidally locked with the moon (it will take about 40 day for us and the moon to turn around once at that point), seems to indicate that it will take about 200 billion years for us to be tidally locked with the Moon.  The sun will become a red gaint in another 5 billion years, so the chances of anyone on this planet being around to notice anything significant would be very, very slim.
803363
dark matter and dark energy and debris
224794
DARK energy and dark matter, two of the greatest mysteries confronting physicists, may be two sides of the same coin. A new and as yet undiscovered kind of star could explain both phenomena and, in turn, remove black holes from the lexicon of cosmology.\n\nThe audacious idea comes from George Chapline, a physicist at Lawrence Livermore National Laboratory in California, and Nobel laureate Robert Laughlin of Stanford University and their colleagues. Last week at the 22nd Pacific Coast Gravity Meeting in Santa Barbara, California, Chapline suggested that the objects that till now have been thought of as black holes could in fact be dead stars that form as a result of an obscure quantum phenomenon. These stars could explain both dark energy and dark matter.\n\nThis radical suggestion would get round some fundamental problems posed by the existence of black holes. One such problem arises from the idea that once matter crosses a black hole's event horizon - the point beyond which not even light can escape - it will be destroyed by the space-time "singularity" at the centre of the black hole. Because information about the matter is lost forever, this conflicts with the laws of quantum mechanics, which state that information can never disappear from the universe.\n\nAnother problem is that light from an object falling into a black hole is stretched so dramatically by the immense gravity there that observers outside will see time freeze: the object will appear to sit at the event horizon for ever. This freezing of time also violates quantum mechanics. "People have been vaguely uncomfortable about these problems for a while, but they figured they'd get solved someday," says Chapline. "But that hasn't happened and I'm sure when historians look back, they'll wonder why people didn't question these contradictions."\n\n“People have been uneasy about these problems with black holes, but figured they'd get solved. That hasn't happened”While looking for ways to avoid these physical paradoxes, Chapline and Laughlin found some answers in an unrelated phenomenon: the bizarre behaviour of superconducting crystals as they go through something called "quantum critical phase transition" (New Scientist, 28 January, p 40). During this transition, the spin of the electrons in the crystals is predicted to fluctuate wildly, but this prediction is not borne out by observation. Instead, the fluctuations appear to slow down, and even become still, as if time itself has slowed down.\n\n"That was when we had our epiphany," Chapline says. He and Laughlin realised that if a quantum critical phase transition happened on the surface of a star, it would slow down time and the surface would behave just like a black hole's event horizon. Quantum mechanics would not be violated because in this scenario time would never freeze entirely. "We start with effects actually seen in the lab, which I think gives it more credibility than black holes," says Chapline.\n\nWith this idea in mind, they - along with Emil Mottola at the Los Alamos National Laboratory in New Mexico, Pawel Mazur of the University of South Carolina in Columbia and colleagues - analysed the collapse of massive stars in a way that did not allow any violation of quantum mechanics. Sure enough, in place of black holes their analysis predicts a phase transition that creates a thin quantum critical shell. The size of this shell is determined by the star's mass and, crucially, does not contain a space-time singularity. Instead, the shell contains a vacuum, just like the energy-containing vacuum of free space. As the star's mass collapses through the shell, it is converted to energy that contributes to the energy of the vacuum.\n\nThe team's calculations show that the vacuum energy inside the shell has a powerful anti-gravity effect, just like the dark energy that appears to be causing the expansion o
32731
That is unknown. There is no way to find out because we can't exit our universe.
262909
Not quite exactly right, Flavio.  \n\nTrue the speed limit for an object moving in space is the speed of light in a vacuum, but a number of proposed methods for "warp" type travel have been developed which don't violate general relativity.  A few years back a physicist named Alcubierre (I think I have the spelling right) produced a solution for Einstein's equations of spacetime which would allow a warped region of space to move arbitrarily fast relative to surrounding space.  Within this warp there can be a region of flat spacetime which would be carried along with the warp.  I've read his paper on it and it's very clever from a mathematical and theoretical point of view, but it's completely impractical given our level of technology, and it also makes some assumptions about things that we simply don't know whether or not they're possible.   Unfortunately, Alcubierre's solution requires tremendous amounts of both positive and negative mass.  "Negative mass" could also be provided by something like dark energy, but then there's the question of what exactly that is.  Its gravitational effects are seen in the universe, but the identity isn't known, and nor is it known how to vary it.  Dark energy could be the result of the zero point density, or it could be a phenomenon that is variable, in which case it's often called "quintessence".  Heim theory, one of the more unusual approaches to a grand unified theory, uses a quintessence instead of a fixed dark energy density, and furthermore predicts the density of quintessence will be related to rapidly moving strong magnetic fields.  \n\nSo, general relativity does allow for a "warp drive" solution, but the spaceship being moved isn't actually moving at above the speed of light but rather is being carried along by the expansion and contraction of spacetime in the warp.  Relativity says that no object with a rest mass can exceed the speed of light (things with no rest mass, like photons, must move at the speed of light in order to exist), but spacetime isn't an object nor does it have an inherent mass.   So, yes, it's hypothetically possible at this point, but there are a whole lot of things we'd need to understand in order to even begin to think about how to engineer such a system, and additional knowledge about phenomena like dark energy may show that it can't be done.  Right now it's still a plausible idea, but this may only be because we don't know enough yet.
460461
A) Galaxy, about 100,000 years.\n\nB) Sun, about 5 seconds\n\nC) Solar System, it depends on if you mean the orbit of Pluto or all the way out to the Oort cloud.
297501
I'm sure you are spekaing strictly hypothetically, but don't forget the closer you get to the speed of light (c), the slower time moves around you.  So if you were to go like 90% of c for 1 year, more than 1 year would pass for everyone else.
955030
The dark matter hasn't gone anywhere.  The problem is we can't see it directly because it doesn't or reflect any light (hence the name!).  It is defninitely there, but we don't know what form it takes - is it normal matter that just happens to be really really dark (dark dust, very faint brown dwarfs, isolated black holes)?  Or is it some form of weird, exotic matter that we have yet to discover (I know that sounds far-fetched on the surface, but it actually isn't).\n\nWe suspect that dark matter exists for various reasons.  One is by observing how spiral galaxies rotate.  By watching any object orbit around another (like our Sun or other stars orbiting around the center of our galaxy) we can calculate the mass of the thing being orbitted.  But with all spiral galaxies (and others, too) the mass we calculate is far greater than the mass of all the stuff (stars, gas, dust) that we can see - therefore there must be stuff in our galaxy that we can't see, but that still has a significant gravitational effect.\n\nWe also see galaxies orbiting each other.  Here again, but watching them we can calculate how much mass there is, since mass determines gravity.  If we only had the mass of the visible stuff inside and outside the galaxies, those galaxy clusters should break apart - the gravitational force from all the visible stuff isn't strong enough to hold those clusters together.  But those clusters do stay together, so there must be more dark matter there between the galaxies.\n\nNow you may just be asking yourself "maybe gravity doesn't work the same on the galactic scale as it does here on Earth", which is a question scientists have asked, as well.  But recent evidence suggests that that is not the case - that we really do need dark matter to explain our observations.\n\nIt gets even weirder - we now think there's something called "dark energy" that is causing our Universe to epand at a faster rate, instead of being slowed down by gravity the way we used to expect.\n\nThere are quite a few good books about this stuff written for laymen - just puruse your local book store in the science section.  And if it all seems too confusing, don't worry - it's confusing to the scientists, too!  As I tell my students, if it all seems to make sense, you're not paying attention!