-Velocity-

They would orbit each other, tidally-locked, at a fixed distance. Occasionally, they would be hit by asteroids and comets. They'll keep orbiting each other until until some external factor interferes- be it the end of the universe, the red giant phase of their host star, another body making a close approach, etc. If they're orbiting in a solar system with lots of planets, such systems are not stable over the long term. Not even our own solar system is stable in the long term, it's actually possible that by the time the Sun turns red giant, one (or two?) of the current inner planets could be gone, ejected after a close encounter with another inner planet. It's impossible to predict, because the solar system is a chaotic system and we can't measure the positions of the planets (and other properties) closely enough to predict their orbits a billion, two billion, three billion years from now. Over such long periods, orbital resonances with other bodies (I think Jupiter being the most significant, despite its distance) can pump up the eccentricity of the orbit of an inner planet to the point where "bad things" start to happen.

It doesn't work that way, supposedly spacetime is flowing into the event horizon at a speed greater than light. So maybe at best you can, I donno, do a few inward-decaying spirals or something before you spiral in and hit the event horizon. I don't fully understand it- I only understand a tiny bit, but just google "orbit within the event horizon" and see for yourself. Everyone says you can't orbit within the event horizon- at least within a conventional black hole geometry, and conventionally, all paths lead to the singularity. Well, you wouldn't feel disruptive tidal forces on a supermassive black hole until just before you reached the singularity, well after you crossed the event horizon. Well, there are almost certainly not such things as singularities anyway, the physicists believe that singularities only appear in our calculations because we don't know the correct description of gravity and quantum mechanics at very high energies and gravitational field values.

You might want to change your post and remove the "but apparently"- or better yet, just remove this sentence altogether. It can be seen as an implication that atheists are less likely to be compassionate, caring individuals than non-atheists, and that is offensive and bigoted. I don't know if that was your intention or not, but that's one way to read the post. The man's religious beliefs had nothing to do with any work he did, so why not just leave them out altogether?

I don't think you can actually orbit a singularity if you're within the event horizon. I thought all geodesics would end up passing into the singularity. I am not certain of this. I'll see if I can look it up and find it somewhere, but someone else feel free to correct me if I'm wrong. Edit: it looks like the conventional answer is that yes, all geodesics go to the singularity, and stable orbits within black hole event horizons are impossible.

Are you talking to me? Why are you bringing up asteroids? I'm not talking about mining asteroids, I'm talking about mining Mars, and using materials on Mars to build spacecraft, sometime in a hypothetical future where manufacturing on Mars is just as easy as manufacturing on Earth, Mars has a large population, and building space elevators on Earth remains difficult. It's a hypothetical future that may very well never come to pass, but if those conditions are in fact met, would not Mars be an excellent spaceport? Mars has volatiles in abundance, something that asteroids have little to none of (mostly none).

I use light pollution maps whenever I move into a new are to find the best places to take my telescope. However, some of these are rather old, and do not reflect recent lighting changes. Case in point: about a month ago, I was driving through West Texas on I-10 and I-20. The area used to be very dark. However, since the last time I drove through the area (no more than 3 years prior), we've undergone a MASSIVE oil boom in the US, enabled by the new "fracking" technology. EVERYWHERE along the interstate, there were brilliantly lit tank farms and drilling operations- and I mean BRILLIANTLY lit. And they were lit from the bottom, too, so the lights were shining up into the sky or at angles. One particular tank farm was so brilliantly lit that, despite being a mile off the interstate (at least), its glare interfered with my ability to see the road. (No one was there, which begs the question why in the hell they have to light it up like they're playing a football game?!?!) Another drilling operation had a "problem" with their lighting. Most of the places they were drilling/fracking/whatever were lit from all sides by brilliant, upward-directed floodlights; however this particular tower had lights only illuminating it from one side. I could see the shape of the drilling tower cast upward into the sky. It was not foggy or hazy out, the only air pollution was whatever the crap the oil wells are releasing into the air. And then there were the places where the sky was glowing orange. That's where they are flaring/wasting the unwanted natural gas that also comes up with the oil. It was unreal. A place that was pristine and dark just a few short years ago is now lit up like New York City. I stopped for the night in Odessa, TX, where I was told I was "lucky" to find a room at one of the 10 brand-new hotels that had just been built for housing all the oil workers. There's a reason that gas in this country is going down. We're going through a nationwide oil boom enabled by fracking. That's a good thing overall, it helps our economy and helps to put more pressure on the countries that don't like us so much. But it's coming at a price- many dark areas are NOT dark anymore. If you live in an area where fracking is going on, you can't trust your light pollution maps anymore, not unless those maps are brand new.

Sure, it's possible they could really pull it off. There are several research efforts going- like this one- that are trying to find cheaper alternatives to the big expensive fusion projects (such as ITER and NIF). Another one that comes to mind is EMC2's "Polywell" research. I'm not sure how viable Polywells are, I just know that the Navy has also been funding that effort. Nuclear fusion isn't particularly hard to achieve- you can build a "fusor" type fusion reactor in your garage for just a few thousand dollars. It's getting net power gain that is so exceedingly difficult. But no law of physics says that there cannot be some cleverly-designed, compact, cheap fusion reactor that gets net power gain. Hence, there is reason to hope, even if it's sort of a long shot.

The Navy does a lot of research on power- new power systems, new power storage, increased power efficiency- these are all big pushes within Navy-sponsored research. I was funded under one such project for a while. Ships need lots of power, and if you don't have to refuel them, that makes your Navy far more powerful- you don't have to have vulnerable replenishment ships chasing around your surface vessels nearly as much. Also, more power and new energy storage technologies allows you to have new kinds of weapons, like EM rail guns, lasers, etc. This is genuine military funding, not "DoE going in through some backdoor". People bemoan US military spending while being completely unappreciative of all the spin-off technologies it creates for us civilians.

No, it's fusion, I had heard that Lockheed was working on this a few years ago. I guess they think they've actually made some progress.

Anyway, the point I'm making about Mars and space elevators is that if we ever gain a large presence on Mars, it could serve as an excellent space port due to the ease of building space elevators there- especially if space elevators remain difficult to build on Earth. Assuming that manufacturing and mining became easy there, then it could be a FAR better place to build and launch spacecraft than Earth. Mars could potentially become "Spaceport Sol".

Nibbs... you simply haven't a clue how space elevators work. You don't have any answer for how tension is built on the cable- and you need tension in order to raise loads up the cable. Have you NEVER twirled a ball on a string before? Or even just a string? What the heck do you think keeps tension on the string?!?! It's centrifugal force. I am also well aware of how space elevators are built; not only have I read many articles on them over hte years, but I also read the Fountains of Paradise by Arthur C. Clarke, one of the modern inspirations for space elevators (though we've known about them from before then). Yes, the satellite that drops the cable must START at geostationary orbit, but it has to raise its altitude as the cable is dropped, because the center of mass moves downward towards the planet. ONCE the cable is secured on the planet's surface, then the cable is lengthened so that enough tension is built (through centrifugal force acting on the end station and cable being greater than the gravitation force pulling down) to allow loads to climb up the cable. Oh and you don't have to take my word for it. Here's Wikipedia: http://en.wikipedia.org/wiki/Space_elevator And if you don't trust wikipedia, here are some scholarly sources: B.C. Edwards, DESIGN AND DEPLOYMENT OF A SPACE ELEVATOR, Acta Astronautica, Volume 47, Issue 10, November 2000, Pages 735-744, ISSN 0094-5765, http://dx.doi.org/10.1016/S0094-5765(00)00111-9. (http://www.sciencedirect.com/science/article/pii/S0094576500001119) Nicola Pugno, Michael Schwarzbart, Alois Steindl, Hans Troger, On the stability of the track of the space elevator, Acta Astronautica, Volume 64, Issues 5–6, March–April 2009, Pages 524-537, ISSN 0094-5765, http://dx.doi.org/10.1016/j.actaastro.2008.10.005. (http://www.sciencedirect.com/science/article/pii/S0094576508003391) A space elevator is extremely simple. It's simply a tether that is so long that the center of mass is above the geostationary orbit of the planet its attached to. The planet simply twirls the tether around in space, causing the tether to be tight under the tension created by centrifugal force. If you put a large massive end station on the tether, then your tether only needs to be slightly longer than geostationary orbit, because the center of mass will be effectively at the end station. Space elevators may potentially have issues with damping out oscillations on the tether- which is something I believe this last source I linked talks about. However, if the station on the planet's surface can move, I think you can cancel out those oscillations. I haven't studied it too closely though. So please, before you start attacking people for being ignorant of something, it's best to make sure that you are not ignorant yourself.

So we think that large portions of any nitrogen Mars once had might be fixed with ammonia, possibly in underground liquid ammonia/water solutions/aquifers?

The stress will "build up"? That doesn't make any sense. Where? Centrifugal force, balanced by tension in the tether, keeps it in place. Go attach a ball to a string. Twirl the ball around your head in a circular motion. What keeps the ball in place? Hint: It's not orbiting in your gravitational field. (Umm... well, hopefully not ) What happens is centrifugal force wants to pull the ball away from the center of rotation. If the ball is displaced so that the string does not point towards the center of rotation, then the ball will experience a restoring force that forces it back to the correct position. That is why worrying about the gravity of Phobos and Deimos "destabilizing" the elevator is nonsensical, because a space elevator is a naturally stable mechanical system. (A stable system is a system that, when disturbed from its equilibrium position, experiences a restoring force that brings it back towards its equilibrium position.) You don't even need a weight on the end of the string- you can twirl a rope around you in a circle without having to attach a weight to the end of it, can you not? The weight of the cable itself can be used as the end mass- but you have to use a longer cable than if you had put a big heavy mass on the end. A more complete model of the space elevator on human scale would be to attach a string to a spinning bowling ball. The bowling ball is the planet. Attach a weight at the end of the string- that's the space elevator's end station. Now, apply an opposite static charge to the bowling ball and to the end weight to simulate gravity. There will be a distance at which the attractive electrostatic force between the bowling ball and the end weight exactly balances the outward centrifugal force. That corresponds to the geostationary altitude. Thus, your string must be LONGER than this length so that the centrifugal force is greater than the attractive force, and tension is kept on the cable. The above model still lacks the simulation of the mass of the cable, but you get the drift.

I am talking about a hypothetical future where we already have a large presence- probably one or several permanent colonies and thousands (or millions) of people on Mars. Then building it on Mars isn't bad. Otherwise, yes, a Martian space elevator would probably be premature, but you don't actually have to build the cable on Mars, only the ground station really needs to be built on the surface. LOL no. You obviously don't realize how miniscule the gravity of Phobos and Deimos are. It sounds like you also don't understand the physics of how a space elevator works. A space elevator is not in orbit.

Come to think of it, you don't need to destroy or move Phobos for a Martian space elevator to work. Mars may not have oceans to build a mobile space elevator platform on, but you could instead just put your space elevator on a N-S track just slightly longer than the width of Phobos, and slide the cable out of the way when a collision would be otherwise imminent. This would cause some waves to travel up and down the cable though. IDEA! Your track does not have to be the full width of Phobos. If you excite a properly-timed transverse standing wave, you can have Phobos fly through a peak or valley of the standing wave. Furthermore, the speed of a transverse wave passing down a tether is proportional to the tension on that tether, so if you spool out or reel in space elevator cable, that will increase or decrease the tension on the cable. This will affect where the peaks are of the various standing wave modes, giving you the ability to vertically position the desired Phobos pass-through points. The reason you want a standing wave is because they are resonant modes and that resonance is what allows you to use a track much shorter than the width of Phobos.

Incorrect. You're ignoring that Mars surface gravity is only 1/3 that of Earth, and of course that drops off quickly with distance- relative to the surface, its gravity falls off even faster than Earth's. This makes it VASTLY easier to build a space elevator there, as it hugely reduces the required cable tensile strength. In fact, the Wikipedia article on space elevators even claims that it is possible to build a space elevator on Mars (and the Moon, I might add) with currently available materials. While I don't know if this assertion is correct, it doesn't change the fact that Mars is still a vastly easier place to construct a space elevator than Earth.

It's when you're in free fall- when there are no external forces acting on you. We're not in free fall with respect to the Earth when we're standing on Earth because the ground repels us and pushes us up. Thus, we "feel" Earth's gravity. We're in free fall around the Sun, so we don't feel the Sun tugging on us, other than some very minute tidal forces. Same goes with the Moon, but the tidal forces are just a bit stronger. I don't know what movie scene you're referring to, but it's probably not outrageous at all. If a plane goes into a free fall, no one inside will feel the force of gravity and everything will start floating around. http://en.wikipedia.org/wiki/Reduced_gravity_aircraft However, with a plane, since there is significant drag (an external force that will try to keep you from being in free fall) I believe that significant amounts of engine thrust is needed to counteract the building drag and maintain the 9.81 m/s^2 acceleration towards Earth's center for any significant period of time.

According to science, everything that is in our universe must follow the physical laws, all the time. That includes your brain. You're claiming that the brain does not follow physical laws, or it can choose not to. So, you're claiming that the brain has supernatural powers- powers that cannot be explained by the application of any physical laws, whether those physical laws are known to us or not. As you're the one making an extraordinary claim for something new that has never been seen to exist, the burden of proof falls on YOU. You don't even have evidence for your claim, let alone proof. It's the person who makes claims- YOU- who has the burden of proof. To say otherwise is like claiming that invisible pink polka-dotted unicorns exist and that the burden is on us to prove that they don't. Ridiculous.

Actually, in the story they weren't using water for nuclear fusion, they were using it as the propellant in their nuclear thermal rocket engines. Which uses a lot more than fusion would- and still they would never run out.

I was simplifying things, you missed the point. And it's not all about adaptability. There's plenty of specialist and semi-specialist species out there that are doing quite fine. A more fit, "stronger" organism is more likely to procreate than a less fit, "weaker" organism. So you can't simplify it into "adaptability" either. But that's missing the point, the point is that the laws of nature are heartless and cruel and NOT something we should model our civilization on, and I think that includes recognizing the uncivilized nature of anthropocentrism.

I disagree about colonization being out of the question. Mars spins fast enough and has low enough gravity to build a functional space elevator quite "easily". We might never get one working on Earth, but it should already be possible on Mars. We might have to destroy or move Phobos though- but Phobos is small enough that this is not out exceedingly difficult. But if we get space elevators on Mars, Mars could serve as a vast mining base for space-based construction, as we could easily get materials mined on the surface into orbit via the elevators.

It's call antropocentrism- this idea that humanity is superior to everything, that nothing else matters besides humanity, that we are naturally entitled to "dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth". I think it's the source of some of our greatest crimes. It's an uncivilized attitude based on the bestial rules of nature where only the strong survive- humans found we could kill anything and destroy anything and it went to our heads. The whole point of civilization and being civilized is about abandoning the uncaring, unforgiving, brutal rules of nature and building a world where compassionate intelligent beings decide what is fair and right. We still find it deeply embedded in our society. Even though we're starting to identify this as being a flaw in ourselves, it's still deeply embedded- look at science fiction, for example. It's still all about "humanity" vs. <whatever>. I think that new "Interstellar" movie coming out looks kinda disgusting or hilarious, I'm not sure which. "We were never supposed to save Earth, we were supposed to leave it" I think is one of the quotes in the preview. So we destroyed Earth, and the movie is about finding the next habitable, life-bearing world for us to destroy next? I would hope Matthew Mcconaughey fails or a more enlightened alien race would swoop in and wipe us out first.

You don't get it. Who cares about things being 100% certain? The Sun might not rise tomorrow because some unusual phenomenon we haven't yet discovered and have never before observed in nature causes it to collapse into a black hole. Because the probability of this (or something similar) is like 0.00000000000000000001%, do you decide that you shouldn't set your alarm and go to work? Of course not. The reality is that we must act on things that are not 100% certain as though they are 100% certain. I use Occam's razor to show that your "one mind" universe is highly unlikely, and useless in terms of a realistic model. It's an interesting philosophical idea to ponder, that's all. Because it's so unlikely, we can ignore it as a possibility, and we can safely say that other minds DO exist, even though we can never be absolutely 100% certain that they do. Only 99.99999999%

One of the quotes from one of the papers I linked yesterday reflects a feeling I have as well. Regarding the speed of light limit- Calling c the "speed of light" is actually an oversimplification; many other things travel at c (massless particles) so besides the electromagnetic force, gravity and the strong force also travel at the speed of light (supposedly, the force carriers for the weak force have a rest mass, and so strangely, the weak force supposedly does not travel at the speed of light). Anyway, for some time I've gotten the feeling that the incredible lengths the universe goes through to prevent anything from violating c is telling us something fundamental about reality. I'm not sure exactly what, but I just get the feeling that the inviolability of c may be one of the most fundamental aspects of existence, and it may reflect something deeper about the universe that we still don't fully understand, or at least, I don't understand. I do know that inconsistent realities (two causally-connected observers can experience entirely different events, an absolute impossibility) can be created using FTL communication using a thought experiment I found.

Don't believe me. Believe the educated, Ph.D- holding physicists. A. E. Everett, “Warp drive and causality,†Phys. Rev. D, vol. 53, no. 12, pp. 7365–7368, Jun. 1996. Available (for me) at: http://arxiv.org/abs/0904.0141 Or this one- F. Lobo, "Exotic solutions in General Relativity: Tranversable wormholes and ‘warp drive’ spacetimes.†Classical and Quantum Gravity Research, 1-78, (2008), Nova Sci. Pub. ISBN 978-1-60456-366-5 Available here: http://arxiv.org/pdf/0710.4474v1.pdf Or, C. Barceló, S. Finazzi, S. Liberati "On the impossibility of superluminal travel: the warp drive lesson" Second prize entry of the 2009 FQXi essay contest "What is Ultimately Possible in Physics?" Read here: http://arxiv.org/pdf/1001.4960v1.pdf I could find many more references but I tire of doing what you guys should do yourself. Warp drives are a fun fantasy, but a fantasy is all they are.