Spyman

Normally the power supply to wall sockets is able to support more current than the socket and the electrical wiring can handle, so to prevent overloading and fires a fuse is used. If the sockets are supplied differently, you need to tell us how. Assuming normal conditions, you can hook up plenty of chargers on a single socket. More load on the socket should not increase charging time. If you load the fuse to much it will blow and all chargers will stop. If the fuse don't blow then all chargers will use their normal charging time, independent of how many that are connected. The chargers should be marked with how much current they need and the fuse with it's maximum current. Add all the loads on each fuse together and just make sure it's below the fuse rating. Some easy Examples: 20 Amp fuse, chargers which use 1.0 Amp each -> 20 chargers max. 16 Amp fuse, chargers which use 1.0 Amp each -> 16 chargers max. 10 Amp fuse, chargers which use 1.0 Amp each -> 10 chargers max. 6 Amp fuse, chargers which use 1.0 Amp each -> 6 chargers max. 10 Amp fuse, chargers which use 0.5 Amp each -> 20 chargers max. 10 Amp fuse, chargers which use 0.1 Amp each -> 100 chargers max. Note that there can be plenty of sockets in different rooms on the same fuse and it's also possible that two sockets close to each other, in the same room, can be connected to different fuses. Lightbulbs and other equipment installed can also be connected to a fuse used for sockets or vice versa. How to find out which fuse is connected to which socket: 1) Read the electrical schematic diagrams, (eg. industrial areas) 2) Find individual markings on the fuses and sockets which match, (eg. hospital areas) 3) At least the fuses should be marked with a working area in the building, (eg. homes, appartments) 4) Follow the wirings from the fuse to all it's connections, 5) Turn on a load in a socket, remove a fuse and check if the power is gone. In most cases I use first No.3 and then No.5 to verify removing correct fuse for a specific socket.

Ronald L. Mallett tries to build a time machine because he wants to travel back in time to save his father, who died of a massive heart attack 1955. http://en.wikipedia.org/wiki/Ronald_Mallett IMHO that cind of time travel is impossible.

OK, so I found this site: http://www.mathpages.com I don't know if it's to be trusted but it seems reasonable. (And it has math for those who like numbers. ) Under "Reflections on Relativity" you can find this chapter, (7.3): "Falling Into and Hovering Near A Black Hole" http://www.mathpages.com/rr/s7-03/7-03.htm So in freefall towards the center you could feel and see your legs on the other side of our EH because from your frame the EH is further in, but for a distant observer, half of you have already crossed the EH. At the EH the geometry of spacetime would be so warped that to move in any other direction than towards the center would aquire speeds higher than c. For the spaceship which is already moving very fast, deep down in the gravity well, touching the EH with a metal bar would be like trying to accelerate its end to c. The bar would in one end try to drag the spacetime anchored by the BH and in the other end try to slow down the spaceship. Depending on the speed and direction of the spaceship, the bar end would need to pass the speed of c already a distance above the EH, since it can't, it would deform and break, caught between the inertia of the spaceship and the BH.

Great, good animation, Thanks again !

It was not until the year 1999 that the origin of the calendrical term "Blue Moon" was at long last discovered. It was during the time frame from 1932 through 1957 that the Maine Farmers' Almanac suggested that if one of the four seasons (winter, spring, summer or fall) contained four full Moons instead of the usual three, that the third full Moon should be called a "Blue Moon." But thanks to a couple of misinterpretations of this arcane rule, first by a writer in a 1946 issue of Sky & Telescope magazine, and much later, in 1980 in a syndicated radio program, it now appears that the second full Moon in a month is the one that's now popularly accepted as the definition of a "Blue Moon." This time around, the Moon will turn full on May 31 at 9:04 p.m. Eastern Daylight Time (6:04 p.m. Pacific Daylight Time). But for those living in Europe, Africa, Asia and Australia, that same full Moon occurs after midnight, on the calendar date of June 1. So in these regions of world, this will not be second of two full Moons in May, but the first of two full Moons in June. So, if (for example) you live London, you'll have to wait until June 30 to declare that the Moon is "officially" blue. http://www.space.com/spacewatch/070525_ns_blue_moon.html

Thats more or less what I said in the OP... Well, for a person like me, not educated in Relativity and with very little knowledge acquired from various sources, simple logic assumes the bar to be softly cut and if continued to be inserted sliced to very thin parts. I don't know if there is any math behind that, except for the mass to radius formula for tidal forces. But there is a lot of "creditable" sources which seems to support it, and even "papers" on how to extend your lifetime if you accidently have crossed the EH with your spaceship. http://arxiv.org/PS_cache/arxiv/pdf/0705/0705.1029v1.pdf (Highly speculative and quite useless if your body and/or the spaceship is separated to small individual parts.) And Wikipedia claims the bar would either not be able to touch the EH or break above it: For the case of the horizon around a black hole, observers stationary with respect to a distant object will all agree on where the horizon is. While this seems to allow an observer lowered towards the hole on a rope to contact the horizon, in practice this cannot be done. If the observer is lowered very slowly, then, in the observer's frame of reference, the horizon appears to be very far away, and ever more rope needs to be paid out to reach the horizon. If the observer is lowered quickly, then indeed the observer, and some of the rope can touch and even cross the (distant lowerer's) event horizon. If the rope is pulled taut to fish the observer back out, then the forces along the rope increase without bound as they approach the event horizon, and at some point the rope must break. Furthermore, the break must occur not at the event horizon, but at a point where the lowerer can observe it. Attempting to stick a rigid rod through the hole's horizon cannot be done: if the rod is lowered extremely slowly, then it is always too short to touch the event horizon, as the coordinate frames near the tip of the rod are extremely compressed. From the point of view of an observer at the end of the rod, the event horizon remains hopelessly out of reach. If the rod is lowered quickly, then the same problems as with the rope are encountered: the rod must break and the broken off pieces inevitably fall in. http://en.wikipedia.org/wiki/Event_horizon (Can spacetime itself become physical and break the rod ???) I don't have any trouble with accepting the "oneway" surface of the EH, but the question of conservation laws still bugs me, (post#20). So where does that leave me, hmm, I would say: "still very confused".

Hey, I did just find out, we have two new smileys -> Very nice, Thanks ! I would also like to use the opportunity to remind of my previously suggestion...

Hehe, I don't have to choose, so I do both of course... Thank you. First, in the OP it's assumed, and it's not impossible, whether nature provides them or not. Second, the rotation could be very low, so the much simpler model suffices as an excellent approximation. The Kerr metric of a rotating black hole is also a solution of Einstein's field equations. If you really have such an urge to prove a breakdown of GR inside the EH, I suggest you start a new thread, specifically for that...

In Einstein's theory of general relativity, the Schwarzschild solution (or the Schwarzschild vacuum) describes the gravitational field outside a spherical, non-rotating mass such as a (non-rotating) star, planet, or black hole. It is also a good approximation to the gravitational field of a slowly rotating body like the Earth or Sun. The Schwarzschild solution appears to have singularities at r = 0 and r = rs; some of the metric components blow up at these radii. Since the Schwarzschild metric is only expected to be valid for radii larger than the radius R of the gravitating body, there is no problem as long as R > rs. For ordinary stars and planets this is always the case. For example, the radius of the Sun is approximately 700,000 km, while its Schwarzschild radius is only 3 km. One might naturally wonder what happens when the radius R becomes less than or equal to the Schwarzschild radius rs. It turns out that the Schwarzschild solution still makes sense in this case, although it has some rather odd properties. The apparent singularity at r = rs is an illusion; it is an example of what is called a coordinate singularity. As the name implies, the singularity arises from a bad choice of coordinates. By choosing another set of suitable coordinates one can show that the metric is well-defined at the Schwarzschild radius. http://en.wikipedia.org/wiki/Schwarzschild_metric Well, I can be wrong and I don't know GR enough to argue with you... (But I trust Wikipedia more than a complete stranger on a forum. )

If a part of the bar is "flattened to zero height" wouldn't that create a gap in the bar ? During the moment of closest approach the spaceship and the bar could be in freefall... EDIT: During freefall the spaceship could with high enough speed, (below c), still avoid the EH and later on start the engines and change course to a safer place. The spaceship is NOT supposed to hoover, at standstill, above the EH. (It passes the BH close and outside of the EH with very high speed.)

In astronomy, heliocentrism is the idea that the sun is at the center of the Universe and/or the Solar System. http://en.wikipedia.org/wiki/Heliocentric All celestial objects inside the Solar system are in freefall, (orbit), around the Solar systems center of mass, since the Sun have about 99 percent of the total mass, the center of mass is inside the Sun. http://en.wikipedia.org/wiki/Solar_system The Solar system is in freefall, (orbit), around the center of mass of Milky Way, which is moving towards the Great Attractor in the direction of the Hydra and Centaurus constellations. In the general sense, the absolute velocity of any object through space is not a meaningful question according to Einstein's Special Theory of Relativity, which declares that there is no "preferred" inertial frame of reference in space with which to compare the galaxy's motion. (Motion must always be specified with respect to another object.) With this in mind, many astronomers believe the galaxy is moving through space at approximately 600km per second relative to the observed locations of other nearby galaxies. Most recent estimates range from 130 km/s to 1,000 km/s. If indeed the Milky Way is moving at 600 km per second, we are traveling 51.84 million km per day, or more than 18.9 billion km per year. For comparison, this would mean that each year, we are traveling about 4.5 times the distance that Pluto lies from the Earth (at its closest). The Milky Way is thought to be moving in the direction of the constellation Hydra, and may someday become a close-knit member of the Virgo cluster of galaxies. Another reference frame is provided by the Cosmic microwave background (CMB). The Milky Way is moving at around 552 km/s with respect to the photons of the CMB. This can be observed by satellites such as COBE and WMAP as a dipole contribution to the CMB, as photons in equilibrium at the CMB frame get blue-shifted in the direction of the motion and red-shifted in the opposite direction. http://en.wikipedia.org/wiki/Milkyway The Great Attractor is a gravity anomaly in intergalactic space within the range of the Centaurus Supercluster that reveals the existence of a localised concentration of mass equivalent to tens of thousands of galaxies, observable by its effect on the motion of galaxies and their associated clusters over a region hundreds of millions of light years across. These galaxies are all redshifted, in accordance with the Hubble Flow, indicating that they are receding relative to us and to each other, but the variations in their redshift are sufficient to reveal the existence of the anomaly. The variations in their redshifts are known as peculiar velocities, and cover a range from about +700 km/s to -700 km/s, depending on the angular deviation from the direction to the Great Attractor. http://en.wikipedia.org/wiki/Great_Attractor Are we at the center of the Universe? No, I don't think so and one should be careful with such claims, it could start an Intergalactic War since those pesky little green men also can make such claims for the same reasons. The mainstream science of today don't consider the Universe to have a center. (At least not in our common 3 dimensions.) Wherever you are in the Universe the expansion are thought to look likewise. If the large-scale universe appears isotropic as viewed from Earth, the cosmological principle can be derived from the simpler Copernican principle, which states that there is no preferred (or special) observer or vantage point. To this end, the cosmological principle has been confirmed to a level of 10-5 via observations of the CMB. The universe has been measured to be homogeneous on the largest scales at the 10% level. http://en.wikipedia.org/wiki/Big_bang In cosmology, the Copernican principle, named after Nicolaus Copernicus, states the Earth is not in a central, specially favoured position. http://en.wikipedia.org/wiki/Copernican_principle Yes, if no force is acting upon the object. Yes, and both mass and energy curves space, so light curves space also. An popular analogy describing gravity is a two-dimensional map where the third dimension is presented as the curvature or gravity. http://en.wikipedia.org/wiki/Image:Spacetime_curvature.png So the bending of space-time could be viewed as the altitude lines in a topographic map. http://en.wikipedia.org/wiki/Image:Topographic-Relief-perspective-sample.jpg Modern physics describes gravitation using the general theory of relativity, but the much simpler Newton's law of universal gravitation provides an excellent approximation in most cases. http://en.wikipedia.org/wiki/Gravitation In this theory, spacetime is treated as a 4-dimensional Lorentzian manifold which is curved by the presence of mass, energy and momentum (or stress-energy) within it. The relationship between stress-energy and the curvature of spacetime is described by the Einstein field equations. The motion of objects being influenced solely by the geometry of spacetime (inertial motion) occurs along special paths called timelike and null geodesics of spacetime. One of the defining features of general relativity is the idea that gravitational 'force' is replaced by geometry. In general relativity, phenomena that in classical mechanics are ascribed to the action of the force of gravity (such as free-fall, orbital motion, and spacecraft trajectories) are taken in general relativity to represent inertial motion in a curved spacetime. So what people standing on the surface of the Earth perceive as the 'force of gravity' is a result of their undergoing a continuous physical acceleration caused by the mechanical resistance of the surface on which they are standing. http://en.wikipedia.org/wiki/General_relativity

In addition to John Cuthber's post, a large amount of raindrops/snowflakes would decrease the visual range too. (But I have seen stars between the clouds during light rain-/snowfall.)

Milkomeda Computer simulations by Cox and Loeb suggest the Milky Way and Andromeda will make their first close pass in about 2 billion years. The two galaxies, currently separated by about 2.2 million light-years, are rushing towards each other at about 310,000 mph (500,000 kph). One light-year is equal to about 6 trillion miles (10 trillion kilometers). During that first close encounter, the two galaxies will circle around each other a few times and their stars will begin to intermingle. The Sun at that time will still be a hydrogen-burning main-sequence star, but it will have brightened and heated enough to boil away the Earth's oceans, other studies predict. The new computer model finds there is a 12 percent chance that during this first brush between Andromeda and the Milky Way, the Sun will be pulled from its present position into a "tidal tail," a streamer-like cluster of orphan stars stripped from their parent galaxies. After the galaxies circle each other a second time, there is a 3 percent chance our Sun will be more tightly bound to Andromeda than the Milky Way. In 5 billion years, Andromeda and the Milky Way will have completely merged to form a single, football-shaped elliptical galaxy. When the two galaxies finally merge, the Sun will be an aging star on the verge of inflating into a red giant. According to the new computer simulations, the Sun and its planets will get pushed out to 100,000 light-years from the center of the new galaxy-4 times farther than the current 25,000 light-year distance. http://www.space.com/scienceastronomy/070514_milkomeda.html

OK lakmilis, nobody knows what the inside of a BH would consist of, how it would look like or if GR would accurately model it, but my point was that GR does not break down. So you agree that the end of the bar touching the EH won't be able to escape and that the spaceship above could still return ? Well it works on Earth, make the test yourself - just try any stairs. (Escape velocity is for a bullet without further thrust.) I will interpret this reply as the bar will be cut off at the EH... What happens to you if you fall into a black hole? Suppose that, possessing a proper spacecraft and a self-destructive urge, I decide to go black-hole jumping and head for an uncharged, nonrotating ("Schwarzschild") black hole. In this and other kinds of hole, I won't, before I fall in, be able to see anything within the event horizon. But there's nothing locally special about the event horizon; when I get there it won't seem like a particularly unusual place, except that I will see strange optical distortions of the sky around me from all the bending of light that goes on. But as soon as I fall through, I'm doomed. No bungee will help me, since bungees can't keep Sunday from turning into Monday. I have to hit the singularity eventually, and before I get there there will be enormous tidal forces-- forces due to the curvature of spacetime-- which will squash me and my spaceship in some directions and stretch them in another until I look like a piece of spaghetti. At the singularity all of present physics is mute as to what will happen, but I won't care. I'll be dead. For ordinary black holes of a few solar masses, there are actually large tidal forces well outside the event horizon, so I probably wouldn't even make it into the hole alive and unstretched. For a black hole of 8 solar masses, for instance, the value of r at which tides become fatal is about 400 km, and the Schwarzschild radius is just 24 km. But tidal stresses are proportional to M/r3. Therefore the fatal r goes as the cube root of the mass, whereas the Schwarzschild radius of the black hole is proportional to the mass. So for black holes larger than about 1000 solar masses I could probably fall in alive, and for still larger ones I might not even notice the tidal forces until I'm through the horizon and doomed. http://math.ucr.edu/home/baez/physics/Relativity/BlackHoles/fall_in.html Let's not complicate things further...

I think you misunderstod my question, I did not mean "caught inside of the EH", I meant "caught inside in the EH". When the atoms in the end of the metal bar gets "frozen" or "glued" will they still be able to mediate the nuclear forces necessarily to ceep the bar together, in one piece, to the rest of the bar still outside. If they will, then the bar would break, if not the bar would be cut off. Wouldn't the nuclear forces be "frozen" in time too, if "everything stops" ?

I am not sure what you are asking. Let's use the metal bar instead, I would like to keep my legs. So the bar gets cut, but it would require work to cut a metal bar in half. How would the "chopping" deal with the conservation laws ? Also from my understanding of GR the same rule would apply to every radius smaller than the EH radius. So if nothing can move up to a higher radius, would everything passing the EH continue to be sliced to the thinnest slices possible as they traverse down to lower and lower radius ?

Hi imp, first I must say that I am an old fashioned guy, so if possible I always try to make my own designs to last "forever". But cheap designs with short lifetime can have a more accurate predictive lifetime, so when safety is involved it is more safe to have parts with a good predictive lifetime and change them before their failure. It could also be more econimically even if the price of five cheap parts is higher than one which function five times longer because the failure itself also have a cost, the loss of expected production and a failure can damage other equipment, material and human lifes. In airplanes a lot of parts have to be checked on regular intervals and some are replaced even if they seems to still function when their predicted lifetime is shorter than next flight. It's expensive but they have to guarantee the travellers some safety otherwise nobody would use them. With cars there is a totally different ballgame, the owner himself needs to ensure his own and others safety, but there is no danger if for example the engine would failure and I think that in all modern cars the breaksystem is doubled to allow for driving until failure. A lot of people can't and won't pay for changing parts that might function for another year or two, so since there is no danger to continue to drive until a failure happens, (might be unconvinient though), they, like me, will keep on driving until the old car breaks down. Automotive builders only have to make the parts last for the warranty time and a big part of the business is that they can earn a lot on replacement parts. Sometimes I even get the impression that some parts are engineered to failure to force the owner to buy a ridiculously expensive replacement part.

Nope, I am not interested in how it would look from different frames, I want to know what would happen to the part above the EH when the other part of the bar get's caught in/below the EH. Would it snap off or be cut off ??? When the spaceship returns to the distant observer they must be able to agree on how the bar is deformed.

So you think that the end of the metal bar that get caught inside the EH would still be able to communicate it's part of the internal, (nuclear), forces inside the metal bar to the outside part and physically break it ?

If I had a hypothetically stair continuing from Earths surface up into space, could I not use it to leave Earth behind at any speed desired ? At least I can increas my distanse a few meters with my stairs at home and I can't se any reason to prevent me if the stairs would continue. So if I was able to withstand the huge gravitational forces and had a likewise stair could I still use it climb out from inside the EH ? (According to your first sentence, Nope.) With GR there is an important difference ! Is it impossible to have a Supermassive Black Hole so big that the tidal forces out at the EH is lower than as on Earth surface ? (Tidal forces is not the issue here.) The downward gravitational force is "perfectly continuous" yes, but is there a force acting upward through the EH, that would keep my legs attached to my body ? (Like if I would change my mind and try to pull my legs out, would I be stuck in the EH ?) If I interpret this correct, then you are saying that the blood in my veins and the signals from my nerves would be able to move up through the EH from my legs to my body still outside but I wouldn't be able to se them any more because photons can't pass. (I really doubt my blood flows faster than c. )

Or you could go here: http://www.scienceforums.net/forum/forumdisplay.php?f=58 (Science Forums, The Original > Other Topics > Suggestions, Comments and Support) Where you will find the poll threads with their names...

Hi lakmilis, I am not quite sure how to interpret your post... Are you claiming that mainstream science and people like Roger Penrose, Abhay Ashtekar, Stephen Hawking, Martin Bojowald and so on... are only making "educated guesses" ??? Hmm, I was under the impression that GR works fine, even inside the Event Horizon, except for close to the singularity, (Planck scale) ? (Hopefully one of the Experts will make a clear statment on that.) You seem to imply that if BH exists, it could still be possible to escape from inside the radius of EH ? (Heh, how did I ever get so conviced that GR forbids that...) Oh and Yes sure, BHs are not definately proven yet, but all evidence so far indicates a high probability, and they are "inevitable in physically reasonable situations". (In this thread the BH is assumed, with a spaceship already there.)

I am not asking about Spaghettification close to normal sized Black Holes. The tidal forces at the Event Horizon of a non rotating Supermassive Black Hole are significantly weaker, since the central singularity is so far away from the horizon. It's a relativity question, with Newton gravity you could still pull out something from inside with a rope, but as I understand GR it's impossible. If I where to put a camera on the end of the metal bar would it be able to send pictures, by cable, out to the spaceship, from inside the EH ?

Would the Event Horizon around a Black Hole clamp a stick that penetrates it like a giant Bench Vice or cut it off softly as if that part would suddenly vanish ? Lets say we have a non rotating Supermassive Black Hole in a big void, (so it is starving), in theory it would be possible to visit the Event Horizon with a powerful spaceship for a short timespan while you pass by, as long as you don't cross it. Now, if the spaceship has a metal bar sticking out and by purpose we let the bar cross the Event Horizon during the fly-by, would the internal forces keeping the bar togheter still act through the Event Horizon, which would deform and eventually break the bar from the inertia of the BH and the fast moving spaceship? Or would the part on the other side be separated without any detectable force on the bar/spaceship? In popular science it is often mentioned that you could pass the Event Horizon of a Supermassive Black Hole without noticing. But I think I would notice if I suddenly couldn't feel my legs anymore and my blood would stop returning from them. Even if you where to pass the Event Horizon very quickly there shouldn't be any difference inside, if "all paths in the forward light cones of particles within the horizon, are warped so as to fall further into the hole".

That's right, I should have used "could" instead of "should".