Is it possible to build a bridge between planets?

Question: What I am proposing is a bridge making it possible to travel between two planets, I have some ideas but I would like to know if and how it would work. Maybe somehow stopping their orbit and locking them in place with a ring like structure or a flexible moving bridge. I don't care if it requires a strong unearthly material I just want to know what and how it would work abiding by the known laws of Physics. I don't want too know what material I would need just if it could be built within the laws of physics.
Comment: If you stop them, you will make them fall into the sun. Just saying.
Comment: Yes: it's called a [_stargate_](https://en.wikipedia.org/wiki/Stargate)
Comment: Not a dupe at all. This one asks for engineering solutions to a much smaller problem. That one just asked for material supply.
Comment: This is NOT a duplicate of the other question!!! The other question and its answers are all about resource supply, not the engineering of the bridge!
Comment: As the author of the previous question, this is definitely NOT the same question, because Mendeleev's is about respecting known physics, whereas I specifically and gleefully gave physics a hard shove off a high cliff.
Comment: Another problem is how long it would take to walk that far. 33.9 million miles from Earth to Mars. Even if you walk continuously at 10mph, that walk would take 386 years.
Comment: What about a *XKCD What If?* style LEGO® bridge?
Comment: Would something similar to a [Space Elevator](https://en.wikipedia.org/wiki/Space_elevator) be acceptable? Maybe not planet to planet... but planet to orbit... planet to moon (assuming the moon is in stationary, geosynchronous orbit)... Or planet to orbit -> orbit to another planet via some sort of cross over/meeting area mechanism?
Comment: reccomended reading is "Ringworld Engineers" by Larry Niven, particularly the foreword.
Comment: @WernerCD Yes that might be ok if we have a that and a inter-planetary bridge like thing, but thanks for the contribution.
Comment: @Benubird Although yes for the process it works but what I want is a physical bridge to really showcase the technology of a civilisation.
Comment: @Caleb707 Good point, maybe walk wasn't the best word I'll update it.
Comment: you can try to read and understand this answer http://worldbuilding.stackexchange.com/a/45273/20315 it may help you to build viable system as it is basically the thing you are asking for.
Comment: I'm surprised no one has considered the composition of the planets. I don't think you can simply attach a perfectly-engineered bridge to a planet and not have the slightest stress cause the foundation to rip off the planet's surface. Planets just aren't that solid at that scale, they are more like balls of viscous liquid.
Answer: Earth. Mars. Yes. Look to Japan.
You have infinite supply of your super material, yes? Good. You'll need a lot of it.
This is a research paper on jointed structures in use today to withstand stresses caused by wind, water, ground motion, etc: https://nathaz.nd.edu/journals/(1999)Mitigation_of_Motion_of_Tall_Buildings_with_Recent_Applications.pdf
Section 6.3 discusses active dampeners, that is, intelligent systems to move things back into place when forces pull on them. Japan has an airport they built on water. The legs supporting the structure are jointed, not fixed, and can respond to tide or earthquake.
You need to build a ring around both planets that will serve as your bridge attach point. The ring will need active stabilizers. The bridge can slide along the ring. The bridge itself is an arc that goes up out of the eliptic plane so that when Earth and Mars are on opposite sides of the sun, it goes over the top. The bridge is built in short segments, each of which actively corrects its position relative to its neighbor. Many segments have slides underneath to stretch or collapse (think like an airport conveyor belt when it goes around a corner) as the distance between the two changes.
Every segment will need power. This may be harvestable from solar. You're on your own for those calculations.
Comment: +1 for accounting for the sun being between earth and mars.
Comment: The segments would need so much power that you could as well add "infinite energy" to the assumptions.
Comment: @Nobody No, that's untrue. I'm only unsure if sufficient can be provided by solar panels, but the power required is actually quite reasonable. I'm still working on numbers (may be a few weeks) but back-of-envelope is on order of Voyager II per segment.
Comment: The ratio between the shortest and longest possible Earth-Mars distance is ~7.4. That's a lot of stretching.
Comment: Why stretch? I thought slack was the obvious answer. I detailed it in my own answer.
Comment: @JDlugosz stretch only because it appears to me to be easy to build in as a feature, and that makes a better (more user-friendly) bridge.
Answer: Introducing an infinitely strong material but otherwise using physics, I guess it should be possible. But note that I'm not considering at all how you'd build something like this, just whether it would work once you have it. You would need to significantly change the orbits of those planets because naturally (without the tether) what is a stable orbit for the duo would not be a stable orbit for the planets alone. This would thoroughly upset any existing ecosystem on the planets. Although if you are into tethering planets together, then I guess maybe you have your ecosystem well enough under control and understood so that you can counteract the consequences to get around the expect mass extinction.
So given a long piece of rope with tensile strength as large as needed:

Tether them together. The easiest way to attach your rope to your planet would probably be to just construct a net around the whole planet from your rope (just dense enough so the planet can't slip out, say maybe three equally spaced not-really-parallels to the longitudes, and three equally spaced not-really parallels to the equator) and attach the interplanetary rope to that net.
For astronomic purposes, your two planets would be one (unless only one of them is colliding with another object, that would be bad): The planets couldn't move relative to each other,
but would have rotation around their common centre of mass. There would be a minimum rotation needed to keep them from crashing into each other. This would make an otherwise completely unstable orbit stable by putting tension on the rope (so that if your system is disturbed, instead of breaking apart, only the tension on the rope changes) This rotation would need to cancel the gravitational force they have on each other. Because on the surface of the planets, the planets own gravity is much stronger than the gravity of the other (distanced) planet, this wouldn't completely mess up the planets individual gravity fields (so at each point of the planet there would be reasonable inward force).
There would still be huge forces on the ropes, but we specifically assumed the ropes won't break. For the net around the planets, you would want to have some minimum thickness of the ropes so it doesn't cut the planet to pieces (it would still have a tendency to lift off the ground on one side of the planet while being forced deeper and deeper into the planet on the other side, but you could surely get that process to be so slow as to just be limit to the lifetime of the planet which is in the far future with which you are not concerned. Or you could replace the netting every couple millions of years).
You could have the planets rotate individually only if you build some giant bearings from your super strong material and let the planets rotate in those bearings. Much much more complicated than the net I suggested. With the net, you could have them rotate in parallel to the connecting rope, but not otherwise. You could have them move fairly erratically if you do introduce too much rotation like this (think gyroscopes).

Now the real question is what happens to the exact gravitational force and what the minimum distance would need to be to have that force behave sensibly.
(I did some work on it, but when I'm already at it I want to solve a fairly general case without too many simplifying assumptions, and this turned out hairy. Not difficult, but lots of calculations. The equations are all nice and well in the right coordinate system, but I need to transform here... You'll get it tomorrow)
Comment: @Michael: Unless you get very funky with orbital mechanics at some point your tether is going to have to pass through the sun.
Comment: @levininja Well, I never did do those calculations I promised, but I expect the distance between the planets would be of the same order of magnitude as the the difference between the major and minor axis of the trajectory around the sun, i.e. negligible when it comes to climate.
Comment: I wonder if the speed that they need to spin around a cenral axis will make the solar wind strong enough to make the planets inhospitable, I'd hope it would cause just enough to create a giant aurora around the planets. That would be pretty...cool. yep,cool.
Comment: Are you sure they would maintain orbits if tethered?
Comment: If you can have an infinitely strong material, why not an infinitely flexible one?  Then the planets can move relative to each other and the bridge will just flex, changing in length and orientation.
Comment: If you're moving planets around why not put two planets in opposite positions around the Sun and have two bridges going above and below the plane of the system? That way you can put the centre of mass for the planets where the sun is and avoid the unstable orbit headache.
Comment: Why should there need to be a huge tension on the tether? If we're not tethering together two arbitrary planets, but trying to pick out conditions under which this would be possible, just take binary planet (a planet and a moon of roughly the same size that are in a circular orbit around a common center with the center of the two traveling around the sun), and put a tether between them. The tether still has to support it's own weight, but does not have to keep the planets together (gravity does that for you).
Comment: I would add to this: the fact that the two planets must rotate around each other would create a problem that the distance between each planet and its sun would be constantly changing, potentially moving it in and out of the habitable zone or at the minimum creating very chaotic weather on the planet.
Answer: I'm very tempted to say that no, that's not possible in practice. At least not without severely stretching the laws of physics. But like Nobody proposed, you could perhaps make it work if you are willing to introduce a super-strong material, plus some other paraphernalia.
Let me introduce you to a few things that belong to the field of orbital mechanics. For simplicity, I will consider only two-body systems, not n-body systems (which are far more complicated to model).

An orbit is an ellipse
The ellipse can be more or less circular, as described by its eccentricity
One of the foci of the ellipse is at the system's center of mass

One of the problems that was solved by the work of Johannes Kepler was that before him, we generally thought of orbits as circular. That isn't the case, and forcing orbits to be perfectly circular leads to all sorts of problems in the long term. By realizing that orbits are elliptical, not circular, Kepler was able to derive a model that described the behavior of orbiting bodies much more accurately.
There is a simple reason why orbits are ellipses. When one body is moving away from another, the gravitational attraction between them is reduced, but so is their relative velocity. Eventually they turn and start falling toward each other instead of away from each other. We call the point farthest from the system's center of mass apoapsis and the point nearest to the center of mass periapsis. When discussing orbits around the Earth specifically, the terms are apogee and perigee, respectively.
Notice how I said "the system's center of mass" above? That was not by accident. We generally think of for example the Earth as orbiting the Sun, or the Moon as orbiting the Earth, but that is a simplification. What really happens is that the Earth orbits the center of mass of the Earth-Sun system (again, simplifying by ignoring all the other bodies in the solar system), and that the Moon orbits the center of mass in the Earth-Moon system. In these cases, the center of mass happens to lie within the more massive body. In other cases, such as the Pluto-Charon system, the center of mass lies outside of either body. Even a small man-made satellite in orbit of the Earth perturbs (tugs at) the Earth ever so slightly. This is Newton's famous apple pulling the Earth toward it in action.
To have a bridge-like construction between two celestial bodies, you need the two bodies to be tidally locked with each other; in other words, they have to always present the same side to each other. Tidal locking happens when one of the bodies in the system is significantly larger (specifically, more massive) than the other, and the distance between them is comparatively small; for example, Earth-Moon, or Sun-Mercury. Tidal locking is a gradual process, but eventually, the smaller body stops rotating relative to the larger body.
The problem with that is that the larger body is still rotating relative to the smaller one. So there is no good anchor point on the larger body!
The only possible solution I can see to this is to use either rotational pole as the anchor point, on both bodies. Then you need to figure out a way to keep the anchor points of the "bridge" from being torn off, but that's an engineering problem, not a physics one. It only becomes a physics problem when you are trying to find a material to build the bridge with.
Now, you've got a bridge. But there's another problem: The elliptical shape of the orbit between the two bodies! Take the Moon's orbit around the Earth, for example; perigee is at 356.4 Mm and apogee is at 406.7 Mm, with a nominal semi-major axis (orbital radius) of 384.4 Mm. The distance to the Moon changes from -8.3% to +5.8% compared to its "normal" value! And the Moon is pretty massive; at about $7.34 \times 10^{22}$ kg, it masses about a percent of the Earth's $5.97 \times 10^{24}$ kg. Unless you can perfectly circularize the Moon's orbit around the Earth first, whatever material you build the bridge out of is going to be subjected to extreme stresses.
You can solve that by introducing that super-strong material Nobody mentioned, and that I alluded to in the beginning of my answer. Now the bridge itself will hold, and may even theoretically be able to hold the Moon at the distance of the bridge's length.
But how are you going to anchor the bridge? If you anchor it to the surface (of the Earth in our example), that surface isn't going to be equally super-strong. And even if it was, the Moon is already massive enough to tug the Earth back and forth a bit in the dance between the two.
Much of that could be solved if you put the system's center of mass exactly in the middle, right there in space between the two. The easiest way to do that is to give both celestial bodies the exact same mass. Now you are looking at a true double-planet system, rather than a planet and its satellite, but I suspect that would be okay, since you specifically said "planets" in your question. This would take an incredibly unlikely coincidence during planetary formation, somewhere along the lines of the infinite improbability drive, but I suppose if you handwave sufficiently, it could in principle happen. It won't be a stable situation, though. A handful of large asteroid impacts could potentially upset the balance, and those happen, in terms of time relevant for planetary formation, all the time.
Barring that, you need the material that you build the bridge from to be sufficiently strong to withstand such forces, and you need the anchor points at both ends to be sufficiently strong to withstand those same forces, and you need the two bodies to be in a perfectly circular orbit about each other, and you need them to be tidally locked with each other (not just one of them tidally locked with the other).
That's sufficiently unlikely to be possible that I would say that while what you propose may be possible in theory it won't be possible in practice.
And walking that bridge would be taxing, but perhaps possible.
Comment: I added some caveats to my answer, I was thinking only about systems already existing like this, not about building them. Like something built by forgotten ancestors/gods/whatever. Completely different train of thought.
Answer: An alternative to (hugely) size-changing bridges would be one Dyson-ring like bridge around the sun, and "off ramp" or "spoke" bridges to the planets.

Still talking crazy scales and structures here, of course, but bridges that slide around the central ring might at least seem more plausible depending on setting.
The spoke bridges would need to curve upwards and down again to allow planets to pass under them. (but this could be a mostly fixed shape).
They would also need to connect to smaller ring-bridges around the planets with a similar setup to account for a planets daily rotation. At this point you might not call it a bridge anymore though.
Notes;

As the spokes slide around the central ring the ring itself could be irregular (a ellipse for example). I have illustrated it as a ring for simplicity.
One issue with this design, however, is at some points two spokes will need to pass each other. The spokes themselves can just be at slightly different heights, but where they connect to the ring there is a "engineering challenge" of letting the connections pass each-other.
Despite this being a mostly rigid design there would still need to be some length variance I believe as orbits are not perfectly identical lengths from the sun.
As mentioned in the comments a alternative design is also possible, where each planet has its own ring for its full orbit, and spokes only go between a planets "orbit ring" and the next one out. Probably more effort to build, but shorter journey times with this design as your not going to the sun and back each time.
Comment: Comments are not for extended discussion; this conversation has been [moved to chat](http://chat.stackexchange.com/rooms/50396/discussion-on-answer-by-darkflame-is-it-possible-to-build-a-bridge-between-plane).
Answer: I'm surprised that only SRM considered that the bridge follows the planets' varying positions, and everyone else wants to lock the two bodies together.
But my thought is to make the bridge flexible rather than varying length as SRM described.
The bridge goes up out of the ecliptic in an arc between the two bodies, accomidating the largest separation.  When the planets are closer together, the arc is taller and/or there are waves.  The overall motion is controlled via a series of waves that travel back and forth; several frequencies and phases at the same time.  It's engineered so the net effect is to crenulate the line by the right amount to give it the proper length between the endpoints at any given moment.
The problem is that the arc passing over the sun will want to fall downward.  It will need constant energy to counter that; perhaps it can be held aloft with solar sails along the length.  Tacking or trimming the sails will give dynamic control to keep the whole thing moving properly.
As far as the terminals go, you could have it just hang into the top of the atmosphere like a non-rotating skyhook, at the pole.  However, if you want primitive people to simply walk, without needing a user-supplied vehicle at each end, it could be anchored to a rotating mount, or the skyhook can trail light cords down to the ground.
Comment: @Durandal A species composed mostly of mathematicians would not care about such practicalities. They simply wanted a surface big enough to finally print out the proof of the classification of finite simple groups. They also created life extension treatments to allow a hiker enough time to walk it through. https://en.m.wikipedia.org/wiki/Classification_of_finite_simple_groups Famous quote from that species: "How many roads must a Mind walk down?" "Just this one, but it's a bugger!"
Comment: The primitive people would want a good set of walking shoes and quite a lot of time. How long does it take to walk 200 million km? Assuming 50km a day it takes a little less than 11,000 years to walk the bridge... even by car, driving at 200km/h straight for 16h a day it still takes 170 years.
Comment: @JDlugosz it occurs to me that the shortening/growing of my bridge design has a side-effect of making the arc uncollapsible, thereby preventing the need for solar-sail stabilization. Thoughts?
Comment: @srm what are you thusting against when lifting the arc up against gravity of the central sun? You need power to work the sliding sections, but that alone does not stop it from falling.  I don't see how simply having length-changing segments would address that.
Comment: Each segment would act like blocks in a keystone arch. I really wish comments could include pictures. Imagine if the St. Louis arch included extendable segments so it could widen or narrow at different times. It doesn't need constant lift. It rests its weight against itself. As the legs are pulled wider by planet orbits, it grows taller to maintain arch shape and stability.
Comment: Arch resting on the planet: OK, this causes the planet to be pushed down below its orbital plane. That will cause the orbital plane to precess and further complicate the motion of the bridge, but I can't tell off hand if this will dislodge the planets or will have a dynamic solution where it precesses.
Answer: No.
Even if you manage to find two planets that are so perfectly aligned in an orbit that they don't seem to move, the forces between them in a case of a tiny-seeming movement would be enormous. Then there is the amount of material involves - the distance from Earth to Mars is 300,000 times the length of the biggest bridge ever made. It's more than 1,000 times the length of the Equator.
The most important consideration though is why. If you wanted to get effectively between two planets, just build a space elevator on both planets. Once you're in space, rocket travel between the two would require much less energy and fuel to travel than it would from the planet's surface. And you'd need a rocket - it's the only sensible way to travel in space (the only other option really is magnetic propulsion on your bridge, but trying to transmit electricity over tens of millions of km won't work very well). You want to keep the vehicle off of the surface to avoid drag... at which point there is no reason to have the surface at all.
Comment: But: We were supposed to ignore material constraints, weren't we? And with sufficient rotation, the distance could be kept much smaller, even less than Earth-Moon, say. Plus I'm not sure, but it seems like transmitting electricity is essentially the same as transmitting light which is in no way limited by distance. You would want to use extremely high voltages to keep transmission losses small, but other than that...
Comment: Possible - however the second part definitely still applies; it doesn't really make any sense to.
Comment: @MattBowyer The reason why is the feat of a bridge although inconvenient is much more grand and can possibly provide living space and other important things. From a storytelling point of view I find it better.
Comment: @MattBowyer Why? To borrow from mountain climbers: "Because it *wasn't* there." Humanity has done some audacious and silly things just in the name of art or providing jobs to unemployed citizens in a downturn or because the leader was insane or... a host of other motivations. But "wouldn't it be cool if..." seems sufficient for many of us.
Answer: It depends,
mostly on what type of structure you let slide as a bridge, and what kind of planets you have in mind. All the potential bridges I can imagine will have in common is: they are more like zero-gravity guide wires (or tubes).
Lets start with a simple system: tidally locked double-planet. The closest we have in the solar system to this configuration is probably the Pluto/Charon pair. A kind of tether between the two could be built and it would be not much different from a space elevator, conceptually. The key point here is that the two "planets" show the same side to each other all the time. Perfectly circular orbit makes this easier, but the tether could compensate for changing distance if its not. This version strikes me as at least not totally impractical, as the distance between the two planets would be small enough that it could be covered with imaginable materials and traversed in useful time.
Next, co-orbiting planets. Thats two planets inhabiting the same orbit around their star, but separated by angular distance. Saturn has a pair of minor moons in this relationship, but their names currently escape me. A structure connecting two such planets would take the shape of an arc along their orbital path. The "bridge" would be mostly free of forces, as long as its mass is neglible compared to the planets. Again, perfect circular orbit makes this simpler, as the length of the arc never changes. The forces acting on the arc could be small enough to be manageable, but the "bridge" would be very long - for an earth like orbiting pair it would be approximately 1 AU long (150 million km), assuming 60 degree separation. Traversing the bridge might be impractical in useful time.
Other configurations have been described by others answers, but I feel these go too far, that after building the "bridge", the planets stop being planets and form a new type of body together with the "bridge". I'm also not sure the planets themselves could stand up to the forces acting on them in that case (or rather I'm pretty sure they won't, unless you reinforce the planets themselves with some super-material).
Answer: It is possible, under very specific conditions which are supposedly possible, but we have no evidence to support that they do exist in nature, and they'd probably form a type of natural bridge as it is so not really needed.
A much better path that can be considered a bridge is something that is considered for the future of the Earth-Moon system which is you build 2 space elevators and the minor distance between the 2 that can be easily traversed in moments. This allows for the continued rotation of bodies seperately, doesn't (for the most part) require super strong materials and still acts as a bridge.
Comment: Minor difference: so you time it so you jump when the Earth cable is passing the Moon's?  Hmm, minor difference in distance does not consider the rediculus difference in velocity.  And how does that idea even apply to two planets orbiting a sun?
Comment: Well you can launch from one to the other, but you don't have to. You just get up to the station and then launch off of it which you would not have the same launch speed doing. The Earth moon system is possible to do this with because the closeness and you'd pretty much be doing it if you built space elevaters on either so it is just a thing that will happen. Between bodies not in such a system you could build what people may call bridges, but not what the OP is talking about. Non-connected relay points to catch and launch like Mass Effect's Mass Relays.
Comment: «You just get up to the station and then launch off of it which you would not have the same launch speed doing.» I don't understand that.   And how does two separate towers moving at high speed at as a bridge?
Answer: So I came across this idea myself and I think I have a solution.
In my world (I'm using mine as an example) I have a moon that orbits the planet at the same speed and in the same direction as the planet's rotation, making it seemingly tidally locked (though the moon still rotates on its own axis). Assuming you have a super material and a ridiculously huge budget, you build the start of the bridge/tether/elevator what-have-you on the main planet, when you reach the moon, the base is elliptically built on the surface, being that the bridge only touches the moons surface at two points and the rest is raised from the surface.
Why though?
If the track on which this bridge slides is elliptical based with the orbit of the moon and its rotation, the elliptical allows for the bridge to be the same distance all the time.

This design also creates a giant "orbital engine" which could be used to generate a ton of power.
Anyway, just an idea.
Comment if my geometry is wrong here...
Comment: Correct me if I'm wrong, but are you saying that the base that touches the moon will slide around the surface of the moon when the moon moves, allowing flexibility?
Comment: Sort of, think of an elliptically shaped belt around the moon, if the distance between the moon and planet is say 5 at its closest, and 10 at its furthest, the bridge itself is 5 and the largest part of the moons 'belt' as it were, is also five. I'll post an image in an update when I can and hopefully that will help you visualize.
Answer: Yes, if the orbits of the two planets are perfectly coplanar (something that won't happen in reality unless your engineers move one of the planets.)
There are a lot of no answers based on trying to build a bridge--which is impossible--rather than the correct answer of building multiple bridges.
Bridge #1:
<code>Build a space elevator.
Build a space elevator 120 degrees away.
Build a space elevator 120 degrees away.
</code>
So long as your planet isn't too massive this is at the edge of what can be built, unobtainium makes it easier but isn't essential.
Bridge #2:
Build a ring around the planet, supported by the elevators.  You can do this with a single elevator if the ring and elevator are unobtainium, otherwise you need at least three points.
Bridge #3:
Another ring around the planet, outside the first ring but touching it with magnetic levitation support (or anything else frictionless if you're going the unobtainium route.)  This ring is not rotating in relation to the central star.  Obviously there is a considerable velocity difference here, some sort of transport craft will be needed for velocity matching unless you go with Heinlien's rolling roads approach.  (Which would take a lot of velocity-matching segments!)  For engineering ease the net force of #2 and #3 combined is zero, the elevator connections are only for stability.  Unobtainium will make the construction of #2 and #3 much easier but it could be done without.
If the orbits are perfectly circular:
Bridge #4:
A ring around the star.  This is connected to #3.  Unobtainium or stationkeeping engines are required.
You build an equivalent system around the second planet.
Bridge #5:
This hangs from the ring around the outer planet, a counterweight hangs in the opposite direction to give a net zero weight.  It extends to the inner ring, again speed-matching shuttles are required.
If the orbits are not perfectly circular it gets harder:
Bridge #4a:
This is in space between the two planets.  Stationkeeping engines are mandatory as it is not anchored to anything.  Unobtainium is required.
Bridge #5a:
This rides a track on #4 (speed matching issues apply) so as to remain aligned with the planet.  It dangles halfway to the planet plus half of the orbital variation of the planet.  It is counterweighted.
Bridge #5b:
This is connected to #3 and extends outward and is counterweighted.  It has the same length as #5a.  #5a and #5b are aligned so as to be coaxial at all times but are only coupled by magnetic levitation or the like as #5b will move up and down with the planet.  A pornographic nickname is inevitable for this pair.  Unobtainium is required.  Keeping the counterweights from #5a and #5b from striking their opposite bridge will be quite a project.
A second pair of bridges connects #4 to the other planet.
If you wish to extend this system to additional planets you can reuse #1, #2 and #3.
I can see no means of handling planets which are not coplanar.
Answer: One step that would make this idea somewhat natural to even begin to think about would be to have a pair of planets where the tallest mountain on each one extends above the atmosphere, making a space elevator unnecessary.
Perhaps, rather than rotating around each other, they would either share a common orbit at some distance from each other, like asteroids in an asteroid belt, or rocks in a ring around a planet, or would have aligned concentric orbits that have lead to the same amount of time in a one year travel around the sun.
Ideally, these planets would also be on the small side of what would still qualify as a dwarf planet, so that the gravitational pull of the planets on each other could be smaller relative to the gravitational pull of the sun on each of the planets. The smaller the dwarf planets, the lower their average distance from each other could be.
Then, you would connect the tops of the super-atmospheric mountain tops with a long glorified rubber band (or with a solid bridge with a glorified rubber band at each end) of something like super-duper spider silk. The rubber band portion or portions would guide the space equivalent of a mountain gondola (greatly reducing the material requirements by requiring only a small proportion of it to have a habitable atmosphere).
Perhaps some spider-like creature that could survive in outer space would maintain the rubber band-like portions of the bridge, repairing it as it is damages or strained by stretching and contraction over the course of a year, perhaps receiving the nourishment to do so from sacrificial offerings from travelers traversing the bridge (or by eating the travelers themselves if they don't offer sufficient sacrificial offerings, perhaps by forcing them onto a dead end spur of the bridge controlled by the space-spider). Thus, the spider would be both a caretaker of the bridge and serve a troll-like role with regard to the bridge.
The entire system (mountains, spider-strands, space spider), except the gondolas used to move along the bridge, could be natural, rather than man made, reducing the need for the people using the bridge to be particularly technologically advanced.
Indeed, perhaps these space spiders evolved in a planetary ring where the distances that had to be traversed with space-spider silk were small, got carried to an asteroid belt when a stray collision of planetary ring material accidentally carried some space-spiders there, and then a colony of space-spiders made it to the planets that were not too far apart from each other when an asteroid crashed there after being disturbed from its orbit by a collision. At each step there would be selection for space-spiders that could produce longer and stronger strands. Related species of smaller, less capable space-spiders in the same solar system could be found in ring systems and asteroid belts throughout the solar system, each adapted to the scale it usually faces.
If the gondolas are too much, or too technologically advanced, or impair the concept too much, perhaps the space-spiders could make flexible space-spider silk tubes (perhaps enhanced with minerals found in asteroid belts, planetary rings and rocky planets) that people on the bridge would simply walk through, rather than something that they would hitch a gondola to. The tubes might be 2-4 meters in diameter or so on the inside, and could extend down the sides of the mountains to which they are anchored down into the area with a breathable atmosphere.
UPDATE: New materials science technology for space is based on spider silk.
Answer: What you need is two planets orbiting each other(in circular orbit) while their rotation is fixed and equal and parallel... Consider this example : take a dumbbell and rotate it while the axis of rotation passes through the center of the handle. Now think the weights are planets and the handle is bridge and you can imagine the scenario.
Comment: or a stretchy bridge
Answer: I agree with the answer of Nobody, but want to add, that the inner planet would move outwards and the outer planet would move inwards if you lock them. So you should ensure that this results in both planets rotating the common barycenter, without adding so much pressure on the bridge, that they destroy the other planet on the position where they are connected to the bridge (your bridge should handle it with its super strong material).
So the moment when you start the locking is very critical here and I recommend to choose a position where the bridge does lay as tangential to the orbits as possible, which will result in the "rotation around their common center of mass" described in other answers.
Answer: No...this would only work if the two planets orbited their sun at roughly the same speed while always presenting the same face to each other, and the chances of the favored conditions for a double planetary system exhibiting these traits is so small as to be zero in practical application.
Comment: Other answers have raised these same points and gone on to address them.
Comment: Yes, but they seemed to always diverge from the main question and concentrate on one point...I was trying to give an answer that summed it all up.
Comment: And your logic assumes that the  bridge has to have a constant length and be inflexible (why are so many assuming that? But SRM didn't and his answer is earlier than yours), and that there was no way to deal with planet's rotation (none possible?).
Comment: Why not talk about how to solve the problems? For example the bridge could rotate around the planet.
Answer: (Slightly) more realistic solution
Space elevators are theoretically possible, so you put one on each planet (these would need to be either at locations that could always "see" each other, so having the cord avoid the sun is another issue...)  Then you have a cord connecting the two.  This cord would have a bunch of slack left over beyond the anchor point on the elevator, so the area traveled would be taunt, but as the planet's orbits move further apart the slack gets added to the taunt cord.  This way the orbits changing doesn't become a problem.  Still not totally realistic,  but the material doesn't need to be strong enough to change planetary orbits.
Comment: This changing distance was covered by SRM's and my answers, in detail. You are not clear on what you mean by slack and taught regions, or how this would be stable (my answer covers stability).


What is the difference between witness node and ordinary node

Question: A DApp developer does not need to run the entire EOS blockchain, if so why would anyone want to be a witness node(full node?) since they are not part of the DPoS consensus. Aren't all transactions performed by Block Producers, does this mean that the only thing a node does is send and receive actions?
Answer: The philosophy behind DPoS is that, even though only a small set of nodes (in case of EOS, 21 Active BPs) are elected to produce blocks, every full node keeps an entire copy of block data & state data.
So basically:

Every full node will validate the incoming blocks, checking signatures for transactions, checking contract execution results, checking if the producer of the incoming block is the elected BP, etc. --- a lot of things that prevent the chain to corrupt.
Every full node could provide READ access to the chain data. As every node has a complete copy, every node could response to read access like getTableRows directly. That's like a whole decentralized CDN.
Of course broadcasting transactions for users. That's like WRITE access to the chain data.
Comment: Lets say some one owns 1% of EOS tokens. Would that mean they could use their 1% stake to acquire 1% network bandwidth provided by the 21 block producers or 1% network bandwidth of all full nodes(incl. Block producers)?
Comment: @DEVANABOINA The name of the "network bandwidth" resource can be misleading. In practice, the network bandwidth cost is just the number of bytes required to encode a transaction. Network bandwidth can be seen as a parameter of blockchain as a whole, and not of individual nodes transferring bytes between each other.
Comment: @Gassa Ok thanks for the clarification. my comment wasn't specific to network bandwidth but any resource that an EOS token can claim a portion of. My sub-question still stands. Do EOS tokens represents a stake in the resources provided by the Block producers only or all full nodes(including block producers & witness nodes)? I find this question to be a followup to my original question but if it is more appropriate to post it separately then i will do that
Comment: @DEVANABOINA What I'm trying to say is this. Staked EOS tokens reserve the right to use a certain amount of _EOS blockchain_ resources. When you decide to use these resources, you implicitly use the actual physical resources of every node maintaining the current state of the blockchain. If a node maintains the current state of the blockchain, it's irrelevant whether it's a block producer or some personal node: it will have to process the transaction.


Should you be notified if a subscribed card is moved to another list?

Question: If I subscribe to a card (but not assigned) and there's activity on it, I'm supposed to get a notification right? When people move their cards to different lists, I don't get a notification in Trello or an email. Is that a bug or is that normal?
Answer: According to Trello's blog on subscribe:
 "When you subscribe, you get a notification about anything that happens to that card: when somebody comments, when somebody gets added, and when it ceremoniously gets moved to the done list."
Did you have the board open when this change happened? You won't get a notification if you were already viewing the board. If you were not logged into Trello or on another board, you should receive the red notification indicator in the top right hand corner.
As far as emailing goes, also check to make sure your notification of emails is set to 'instantly' under notifications in your user profile.


How do I tell TOR to not cache Onion descriptors?

Question: When I run tor.exe and try to make a connection to a .onion domain via SOCKS and the hidden service is available at that moment, the connection opens quickly. Conversely, if the hidden service is not available, the connection fails after a while. Now let's say that the hidden service turns back online after one minute; it takes my tor instance about 5 minutes to successfully connect to the hidden service, like it was caching the (bad) descriptor of the onion domain.
Is there a way to tell tor.exe that this time window should be lower?
Answer: You probably don't want to do this, for performance reasons and potentially for anonymity reasons.
Tor does cache rendezvous descriptors. The simplest way to clear this cache is to use the 'New Identity' option on Tor Browser which, amongst other things, sends a NEWNYM signal to the Tor process over the control port.
Part of the process that Tor performs on receipt of the NEWNYM signal, is that it clears out the rendezvous descriptor caches. Shortening the time that descriptors are held will only result in degraded performance and potentially could make your Tor usage look different from other Tor users.
If you know the .onion has republished a new descriptor, or suspect it might have then send a NEWNYM signal and try to contact the .onion service again.


Whats an easier instrument to play than trumpet, with mouth, but still a brass instrument?

Question: Recently I joined my school band. My teacher is having me play trumpet, but the mouth piece is sooooo uncomfortable. I struggle a lot to reach the higher notes especially. My teacher told me that all of the instruments are like that, but from how small the trumpet mouth piece is compared to the trombone for example, they can't possible be required to regularly reach as high of notes as trumpet players (within the mouth piece). Should I just keep trying, or switch to an different brass instrument?
Answer: This is just from my personal experience, but when I started band (about 7 years ago). I was put on the baritone/euphonium; I think I experienced a similar problem to you where reaching higher notes was almost painful. The next year I switched to the tuba and WOW the mouthpiece was so much more comfortable for me. I think it's easier on instruments with larger mouth pieces like the tuba because the usual higher tuba notes tend to be the lower ones on say the trumpet. I would suggest trying a baritone/euphonium, trombone, or even a tuba (if you don't mind having to carry it home and to concerts).
Comment: I think you are right that I should try one of those. I just wish they were not so large in size because carrying them on and off of my school bus might be a hassle.
Comment: Well most school buses, at least in my area, have huge storage compartments underneath. You could ask the bus drivers for the key to store the instrument down there, because I doubt they would want to see you struggle trying to carry a tuba in its case all the way up and into a school bus seat. *but I have had to do that on few occasions*
Answer: I agree with Erika and Tim. But also, ultimately, you will need to develop the muscles and technique to reach the higher notes on whatever instrument or whatever mouthpiece you decide to use.
On the lower instruments, like tuba, you often are not required to play the higher notes for that instrument as often, so in some ways it is easier. And often there is more of a need for lower instruments. But whatever you choose, try to make sure to practice at least a little bit every day! With brass instruments you can even practice with just the mouthpiece, or even just buzzing your lips without a mouthpiece. Even this kind of practice, everyday, will eventually help you hit the higher notes.
Good luck!
Answer: Instead of switching instruments, try swapping mouthpieces. You may find other trumpet players with different mouthpieces they'll let you try, or go along to the local music shop, and try a few out. Since we're all different, the manufacturers make other options available.
Comment: Hear hear! Even our teeth can play a deciding role, where changing mouthpieces can make all the difference. I had better range and endurance on euphonium than a much smaller trombone, until I got a (custom-made) trombone mouthpiece whose rim matches the euphonium mouthpiece, simply for the way its curvature parallels my upper teeth. At last high notes became slightly easier on trombone than euphonium, as would make sense.
Answer: Yes, some people are better suited to an instrument with a larger mouthpiece, like trombone, baritone horn or even tuba.   (And yes, the larger instruments ARE larger and therefore more of a nuisance to carry.  You can't have everything easy AND easy in this world!)
Maybe the shape of your teeth really make a trumpet mouthpiece uncomfortable.  Or maybe you're trying to get the higher notes by pressing hard rather than by forming a proper embouchure.  You can only really sort this out with a teacher.
Anyway, it's over a year since you asked the question.   What DID you do?  Are you still playing?
Answer: I think that larger mouthpieces are going to be more comfortable, on average.  My son plays the trombone and doesn't get as fatigued as I do.  Of course, with exceptions as you enter more demanding scenarios, the range requirements for lower brass seem to be lower.
However, most kids also start playing trumpet with a Bach 7C mouthpiece, which is very uncomfortable (I heard a unsubstantiated story that it was made uncomfortable, on purpose, so that students would be less likely to adopt a playing technique of using too  much lip pressure while playing).
Is your teacher a brass player, or is he a general music teacher?  If the later, you might want to consult a more experienced trumpet player for better advise.
Answer: I have found the trombone very easy and I think it is better than the trumpet and easier to play. If the trombone seems to hard, don't worry, it is really easy.
Comment: All brass players need excellent breath control.  The larger instruments need control of a larger quantity of breath.  Yes, a trombonist's arm has to reach the length of the slide.  But this isn't insuperable.  I went to school with a lad who was a victim of Thalidomide, the drug that was intended to cure morning sickness during pregnancy but resulted in children with malformed limbs.  With a little mechanical ingenuity he became a fine trombone player.  Here's another. Respect!  https://www.youtube.com/watch?v=IyCAPcE7MjU
Comment: Could you expand on this post? Are higher notes easier to play? Is the embouchure easier on trombone? Are there any added difficulties on trombone that don't exist on trumpet (e.g., having arms long enough to reach low notes, breath support, etc.)?


Between functions.php (theme), widgets, and plugins, which is loaded first?

Question: Customer asks if a specific carousel plugin he uses can be widgetized. That means I should create a widget inside functions.php which calls the plugin's function. That means that the plugin's code has to be loaded first so that the function be available to WordPress when the functions.php file is loaded, right? Would that work?
Comment: Hola consulta para llamar una api externa en que parte de wordpress lo tendria que hacer? gracias
Comment: Hi - you've posted this as an answer to an existing question, whereas it's really a new question. Could you ask this as a new question please? This site is in English but there's also [Stack Overflow en español](https://es.stackoverflow.com/).
Comment: But the broad answer I think is that you can call out to an external API from anywhere in a plugin or theme. You should generally cache the response though and avoid long-running requests if you can. If you do reask this question please provide more details about the API you're calling out to and what you want to do. Thanks!
Answer: The plugins are loaded right before theme (yes, I've been looking for excuse to use this):

However it is wrong to think about either as point of code execution. For most cases everything should be hooked and executed no earlier than init hook. According to Codex widget registration with register_widget() should be hooked to widget_init.
Because of that order of load doesn't matter for this case, you will have everything loaded by the time widget needs it in any case.
Comment: @jgraup you say that like things change in WordPress core... :)
Comment: Any chance we can get an updated chart in 2016?  ;-)
Comment: @Rarst, touché  ;-)
Comment: WP core load will never make any sense.
Comment: @IsaacLubow yes, the things in more than one column run for those respective contexts, as you can see the same significant chunk of core load is always involved for any request.
Comment: Just so I'm sure I understand this chart - The sections that extend across more than one of the 3 main columns are common to all? So I'm following a vertical line downward and crossing the events in chronological order for a given request?
Answer: One interesting approach would be to list all hooks to a file in a sequence of execution.
add_action( 'all', '_20161224_printer' );
function _20161224_printer( $r ){

    $line =  microtime(true)*10000 . ' ' . $r .  "\n";
    $fp = fopen( ABSPATH . 'hooks.txt', 'a+');
    fwrite($fp, $line);
    fclose($fp);

}

And you will get the output like this:
14825992300742 pre_option_blog_charset
14825992300743 option_blog_charset
14825992300743 plugins_loaded
14825992300744 load_default_widgets
14825992300745 load_default_embeds
14825992300745 wp_audio_extensions
14825992300745 wp_audio_embed_handler
14825992300746 wp_video_extensions
14825992300746 wp_video_embed_handler
14825992300746 sanitize_comment_cookies
14825992300747 pre_option_permalink_structure
14825992300747 option_permalink_structure
14825992300748 pre_option_wp_user_roles
14825992300748 option_wp_user_roles
14825992300749 wp_roles_init
14825992300749 setup_theme
14825992300749 pre_option_template
14825992300750 option_template
14825992300750 template
14825992300750 theme_root
14825992300751 template_directory
14825992300751 pre_option_stylesheet
14825992300751 option_stylesheet
14825992300751 stylesheet
14825992300752 theme_root
14825992300752 stylesheet_directory
14825992300752 pre_option_WPLANG
14825992300753 query
14825992300754 default_option_WPLANG
14825992300755 locale
14825992300755 override_unload_textdomain
14825992300755 unload_textdomain
14825992300755 override_load_textdomain
14825992300756 load_textdomain
14825992300756 load_textdomain_mofile
14825992300756 locale
...
many many more action hooks
...
14825992302886 wp_parse_str
14825992302886 nonce_life
14825992302886 salt
14825992302886 wp_parse_str
14825992302887 esc_html
14825992302887 logout_url
14825992302887 clean_url
14825992302887 gettext
14825992302887 wp_after_admin_bar_render
14825992302888 pre_option_template
14825992302888 option_template
14825992302888 template
14825992302888 theme_root
14825992302888 template_directory
14825992302889 parent_theme_file_path
14825992302889 shutdown

Note the full list simply could not fit the 30.000 characters limitation per WPSO post, so I removed many action hooks.
Put the above code inside a plugin. If you do that from the themes functions.php you will not catch plugins_loaded. One another proof the plugins are loaded before the theme.

The possible goodies of this check are many, but please note the output will be different for different page templates you will call, or if you are in a dashboard.
I simply called this from /?p=1 or Hello World page.
If you don't have a single plugin activated, you may put this code into mu-plugins folder.
It may be better to use WP FS API, but this way is realy concise.
Comment: Inside wp-admin plugins are loaded after the theme or in the order of the installation... and in front-end plugins are loaded before the theme...
Answer: You can have a widget inside the plugin's .php file (and have a shared global variable which they can both use), if that's what you're asking. Here's a tutorial with sample code I stumbled upon a while back.
Also, here's a list of actions run during a typical request, in order of execution. #2 and #10 suggest that plugins load first; not sure about functions.php.
Comment: Correct, plugins are loaded before theme files. If the plugin includes code, but not the widget you want, it is possible to define the widget in your theme's functions.php.


How do you prevent mold in CamelBak hydration bladders?

Question: When using a CamelBak (or other hydration bladder system), it is easy for mold to grow if the bladder is left sitting with water in it. What is the best way to avoid mold (or other nasties) growing inside in between trips?
Answer: CamelBak have a great answer in the help section of their website. Summarising their recommendations:
Keep it clean and dry when not in use. If mould develops:

Use hot water and two tablespoons of baking soda or bleach
Leave for about 30 minutes
Wash with hot water and mild soap
Air dry
Comment: I would add to make sure to hang it where water will run out and it will dry.  You can put the bite valves through most dishwashers to get them thoroughly clean as well.
Comment: This does work and extends the life well, but I feel it just delays the inevitable. I usually replace the bladder after 3 or 4 years when the bleach just isn't keeping it at bay any more.
Answer: I clean it out then leave it to dry for a day or two. But you can never seem to get all of the water out of the hose, so I keep mine in the freezer. At -18 the mold can't grow.
Comment: I leave mine hanging upside-down for a day or so, and any remaining water collects near the bite valve. A quick pinch & shake helps get rid of this water.
Answer: Leave the filler cap open to allow any water residue inside to evaporate and so the humidity level of the air inside the bladder matches that of the air in the environment around it
Comment: This is basically what I've done for nearly 20 years with my platypus.  May also want to take off the bite-valve on the straw so the straw has airflow through it.
Comment: I tuck a half of a paper towel inside next to the filler cap to wick away and dry that crease.
Answer: This is why I like the pouches that have a zip-lock bottom as well as a cap on the top - it makes it a lot easier to clean the inside and leave it open to let it fully dry.
My friend also swore by leaving the pouch in the freezer when not in use - this would obviously slow down mould growth considerably in between uses.
Answer: I used a blow dryer on low setting to dry the bag and tub, and a paper towel pouch (twist tie close) with rice - I figure if it gets moisture out of a cell phone and salt - it ought to work for a Camelback. I also save the little silica gel packets that come in vitamin bottles and new shoe boxes and may try those.
Answer: I just get it mostly dry and then pop it in the freezer until the next use. This keeps anything from growing and takes 30 seconds and no cost.
Answer: I would suggest:

leaving the cap open, letting it air dry,
then sealing it up and keeping it out of direct sunlight in a dark area (perhaps inside your pack).
When you are ready to use it again, rinse it a few times - run some water through the hose as well.
Answer: I get food-grade 3% hydrogen peroxide (NOT 35%) from my health-food/ vitamin store and put a cap-ful in any water container then fill it to the brim. It works really well to kill microbes of all kinds by oxygenating the water, and you can drink it in that low of a concentration (it is used in commercial food preparation, and some people believe that drinking oxygenated water is actually good for you as well).
Answer: I use a reservoir dryer to hang my reservoir open and upside-down, and...

Only ever fill with water
Empty and dry every night, even if using it the next day
After about half an hour of drying pinch the bite valve and shake to remove any extra water, and also shake the reservoir with the opening facing down to remove any water that has collected
Pack it all away after about a day, or once things look nice and dry

I've been following this approach with the reservoir for the CamelBak I bought in 2005 is still going strong, with no mould or other nasties inside!


How do I enable desktop icons on elementaryOS 5.0 Juno?

Question: Old ways of installing Nautilus do not work.
Comment: What exactly doesn't work?
Comment: Right mouse button and there is no home folder and the mounted disks. Instruction: https://elementaryos.stackexchange.com/a/3858/15127
Answer: Install Desktop Folder from App Center
Answer: Strangely, VirtualBox was able to put an icon on the desktop. The .desktop file it created is in ~/Desktop/, no surpises there. And it works! So it looks as if the capability is still there, all they took out was the tools to create desktop items from the GUI. If you are comfortable creating .desktop files from scratch, it should be possible.
Answer: There is a utility available called Desktop folder which can enable desktop in Elementary OS . You can install it via AppCentre with a click and use it.
It provides a lot of other features and is really hand. The fact that it's no third party and is available via AppCentre convinced me it's not going to break something.

You can access files, folders and applications from your desktop.
Activates the right click on desktop.
Supports drag and drop for files, apps, links inside panel to quickly use next time.
You can also resize the panel, reposition it on the screen and change background colours.
You can keep notes on the desktop and display photos.
It also revives the desktop by enabling Super Key + D to display Desktop at any point of time.

Source : Enable desktop in Elementary OS
Comment: Your answer is correct. I do not know why somebody downrated it, but there is also the same answer, accepted years ago, with less information compared to your, but it is the same solution you are providing. I recommend you before answering a question to check out the other answers.
Comment: I see, yes. This should have probably gone in the comments to the above answer - I don't know how I missed that.


How do you name Sprints in Scrum?

Question: I was wondering if it's a good idea to name Sprints with user-friendly names instead of using numerals like Sprint 1, Sprint 2, etc. Are there best practices or standards for naming the Sprint after themes or major milestones for the project?
Comment: I found one thread with interesting stuff at http://programmers.stackexchange.com/questions/82732/how-do-you-name-sprints-in-your-projects
Comment: Wondering around the internet, the comment session of [this blog post](https://www.mountaingoatsoftware.com/blog/number-name-date-stamp-or-sing-your-sprints) confirms that there's no canonical answer for this question - the best naming pattern is _the best one that works for your team_.
Comment: @TiagoCardoso scrum alliance has removed all of their user contributed articles. [The archived version of the blog post can be found here.](https://web.archive.org/web/20160304031942/https://www.scrumalliance.org/community/articles/2009/january/the-product-vision)
Answer: TL;DR

I was wondering if it's a good idea to name Sprints with user-friendly names instead of using numerals like Sprint 1, Sprint 2, etc.

No, it's not a good idea.
A sprint is a container where Product Backlog items are temporarily stored for a brief duration. A sprint may produce some project artifacts, but the sprint itself has value only as a time-box. Even if you can find a use case for tracking sprints by name, giving sprints non-ordinal labels reduces ease of communication and the amount of information conveyed by the name.
Sprints Are Ephemeral
A sprint is the name the Scrum framework gives to a time-boxed iteration. While each sprint has a defined Sprint Goal, the sprint itself is not a project artifact that needs to be kept for historical records or process improvement.
Sprints often result in various outputs that are relevant to the project such as velocity measurements, finished features, new user stories for the Product Backlog, or process improvements, but the time-box itself has no lasting value once it has expired. Regardless of whether the Sprint Goal was met or not, the old time-box is gone forever and a new time-box for the next sprint replaces it.
Giving code names or handles to a sprint therefore makes little sense, since any given sprint should have no utility as an historical referent. Trying to map ephemeral time-boxes onto named events is usually a project smell that the development model is not truly iterative.
Sprints Aren't Milestones
While each sprint has a Sprint Goal and a set of items peeled off the Product Backlog, neither of these things is necessarily a project milestone. Goals are not always unique items, and stories are sometimes placed back onto the Product Backlog (modified or unmodified) for future sprints. Therefore, there is no guarantee that a sprint is actually unique.
For example, if your current sprint does not meet its Sprint Goal and the Product Owner decides to have another sprint with the same goal, would you name the sprints the same? If not, would "Sprint Fuschia" following "Sprint Aquamarine" really tell anyone anything useful about the sprint, the project, or the team?
In the database world, the problem of (potentially) non-unique rows is generally solved by assigning auto-incrementing primary keys to each row. This is one reason that Scrum generally uses incremented integers rather than code names or handles for labeling sprints.
Projects Evolve; Sprint Labels Shouldn't
In Scrum, the guiding principle is "inspect and adapt." While a project may have a schedule with defined shipping dates, the contents of any given sprint is expected to change over the course of the project. Given that the output of one Sprint impacts the contents of subsequent sprints, it would make no sense to assign meaningful code names to each sprint in the project schedule ahead of time since the goal or stories for the 23rd sprint may change by the time the team gets the first 22 sprints out of the way.
Alternatively, if you use colorful but meaningless names, what value have you added? At least sequential names give you sequence information; if you name your sprints after trees, endangered mammals, or exoplanets, what useful information does that actually convey to anyone?
Since we've already established that sprints are ephemeral and carry no historical significance (other than perhaps as velocity data points), what is it that you might want to communicate about Sprint Koala (which was three sprints ago) to someone else during Sprint Wallaby? Other than as an abstract referent, how will its name add value to the communication?
Unless you are mapping sprint names onto a sequence anyway, and know that Sprint Koala was the 23rd Sprint and that Sprint Wallaby is really the 26th, you can't even convey ordinal or time information without additional cognitive load. That seems like the opposite of "user-friendly" to me.
The Value of Ordinal Information
While the name of the sprint is rarely useful, the number of sprints in the current project plan or the team's current progress along the plan's ordinal axis do provide some utility. For example, a plan with 25 two-week sprints can be estimated to take 50 weeks. Likewise, a project that has less than 30% of the remaining Product Backlog completed after consuming 50% of the planned iterations is quite likely to be out of tolerance.
I don't know how to divide a gaggle of geese by two koalas and a lemur, so I'm pretty sure that these sorts of names provide no value in managing project metrics or even simple percentages. In contrast, assigning ordinal numbers as labels provides for some useful math functions to monitor and communicate about your project, even if the contents of past and future sprints are neither known nor tracked.
Answer: Name the Sprint after the Sprint Goal
If you want to name a Sprint, I agree with the accepted answer in the programmers.stackexchange.com thread that you should name it after the Sprint Goal. As the Scrum Master, I keep pushing the Product Owners to come up with a well articulated Sprint Goal. I always start my Sprint Planning sessions by inviting the Product Owner to state the Sprint Goal.
However, coming up with a Sprint Goal is the harder part. Here are some tips from Roman Pichler on how to go about identifying a Sprint Goal. Once you have the Sprint Goal identified you can try and extract a shorter version of it for the Sprint Name.
Comment: If the most important ticket in a sprint is to get the login system working, then the sprint name could be "Login system sprint". The sprint goal doesn't have to encompass *all* of the tickets in a sprint, just the major ones.
Comment: In my experience, the Sprint Goal is usually "get these stories done".  I've thus never found the sprint goal useful, and no one sees any value in spending time crafting a sprint goal.  Any tips for me?
Comment: I upvoted this answer a few years ago, but my experience since then has shown this is problematic. There's nothing in the framework or in real-world applications of Scrum principles that prevents teams from having non-unique Sprint Goals. If Sprints are treated correctly as ephemeral time boxes, this may not be a deal-breaker, but may still be confusing if you have more than one Sprint with a goal like "Embiggen the Main Widget." This can and does happen in the real world, so your mileage may vary.
Comment: "Get these stories done" can be a smell. Consider asking questions like, "What problem are we solving and for whom?" during refinement, Sprint Retrospective or Sprint Planning. Scrum can be a catalyst for getting more done quickly, but it's not a guarantee that the "right" product is being built.
Answer: There are different conventions I've seen used. In my opinion, even having one is completely irrelevant, besides giving you something to refer to in discussions (which may or may not be a good thing!)

Use a «Sprint N» or «Iteration N» convention:
Pro: Easily generated
Con: Is anyone going to remember what you did in iteration 23? It's almost like not naming them since each sprint already has an ordinal number
Notable Example: Brackets
Use a «Sprint of dd of mmm» template:
Pro: Easily generated, for some people date anchoring helps them remember in which sprint something was done
Con: It's almost like not naming them since each sprint already has a starting date
Notable Example: Not that I can think of, but it seems quite used
Give sprints a name based on goal:
Pro: Makes it trivial to remember when something was done
Con: Hard to generate, hard to remember (name the first 20 sprints by heart)
Notable Example: Not that I can think of
Any combination of the above

All in all, here's my best advice:

Don't do it unless you need to: what is the value of doing so?
If there is a concrete need, let the team discuss the need
If the team wants to name sprints, let them propose and vote on a convention
Victory

See also: https://softwareengineering.stackexchange.com/questions/82732/how-do-you-name-sprints-in-your-projects
Comment: Ages old post, but timeless, how about we have a sprint's name ordinal connected with a single release that follows the same naming scheme, and tickets tagged with that name of the release; thus we can have a well-tracked project?
Answer: Not sure how it came to be, but in my last two companies we used the following Sprint naming format: Year+StartWeekNumber+Teamname. Resulting in something like "2016W10 Team Blue" for our current sprint.
But in the last 7 years of doing Scrum I never felt the need to use the Sprint numbers after the sprint was done. Although sometimes it might be handy to see in which time period a feature was developed from in Jira.
Instead of naming a sprint I would define a clear sprint goal and keep the name of the sprint very simple: http://wall-skills.com/2015/sprint-goal-focus-for-the-scrum-team/
Comment: We do something similar. YYYY-NN where N is the an ordinal number 1-26, one for each two week iteration.
Answer: I have a slightly different take on this.  Our team has evolved an approach (branching model, organisational structure, overall approach) which allows us to run multiple sprints in parallel - this is especially useful for ensuring high utilisation, so nobody is sat idle waiting for QA to finish their task.
The downside is, at any given point, we don't know which sprint will go out first, thus date-based, or ordinal naming is useless.
Thus we went for the 'colourful but meaningless' approach and named our sprints after moons in the solar system (there are quite a lot!).  The names themselves don't convey anything, but its a very useful way to be able to talk about a collection of features, enhancements and fixes in a way that everyone involved can relate to.  I take issue with the assertion that your sprint name HAS to mean something - in our case its simply a logical grouping.
We've ran with this system for over two years, over something like fifty point releases, and it works very, very well.
For example, we currently have sprints 'Phoebe' and 'Ceres' in development - the project plan calls for Phoebe to become the next point release (1.80.0) but there are no guarantees, and we remain agile enough to change the planned order of releases, with minimal impact on delivery.  Thus we may find problems with Phoebe in the QA cycle that delays it, and Ceres will go out as 1.80.0, and Phoebe will (probably!) become 1.81.0.
Comment: Can you please describe this system in detail?
Answer: To echo CodeGnome a little, I would also say that naming sprints is a bad idea. They are ephemeral. Once a sprint has completed you may wish to gather the completed stories into a record for later use in completing user documentation, but aside from that there is nothing to be gained from remembering any particular sprint, and naming them would give them too much significance.
What may work more effectively and be a better focus for your team is to look at the goals of the release that the sprint is part of and keep those goals in mind. Having a release name is a time-honored tradition since before agile methods. It forgoes tying the stories of any one sprint to any significance, however it does emphasize that all the stories in the backlog for the release are necessary before declaring victory.
Answer: I use "Sprint N: Sprint Goal", restarting the count after every release.
In practice, we often use only the number, but the number+goal is helpful when reporting over a longer scale, or looking back over the past few months to see where we've put our effort when prioritizing for future sprints.
Answer: The name of the Sprint doesn't have any impact on or make any difference to your process. But it is recommended to use numbers such as Sprint 1, Sprint 2, etc. for ease of tracking.
For a large project you may have 30 or 40 sprints. In that case it will be difficult to identify the sprints if you give them fancy names. So its better to name using numbers (Sprint 1, Sprint 2, etc.).
Answer: Though there is no right or wrong answer to this question, I have found it useful to use the last day of the sprint as the unique identifier for the sprint name.
As as example, if a sprint ends on 03/28/2016, I would name the sprint as:
Sprint 20160328
I have found that this works very well for the purposes of:
(1) giving the sprint a name that provides useful information about the sprint rather then some arbitrary number
(2) using a date ensures uniqueness within the context of an individual project
Note: I never coach embedding elements of the program or project name in the sprint name itself. Topologically, it's cleaner to let the project and/or program exist at a level well above the work time box label.
Answer: If you have project divided into Milestones (1,2 ...5), you can name the Sprints inside each milestone to correspond to Milestone your are working on and the # of sprint in that Milestone.
For example if you are working on Milestone 1 - your sprints can be named Sprint 1.1 ; Sprint 1.2; for Milestone 2 - Sprint 2.1; Sprint 2.2
This way you have a reference point to a Milestone and functionality executed.
Answer: I advise not to fret over such small details. The idea of SCRUM is to reduce waste and be agile. Find a simpler way and stick to it.
I use the following format so that I do not have to think about naming.

Sprint X - From to To

where

X - Sprint number (e.g. 15)
From - Short start date (e.g. 19 Mar)
To - Short end date (e.g. 2 May)
Answer: I work with diferent teams and we have parallel sprints for different apps.
It turned really hard to differentiate several Sprints with differents numbers.
So we implemented the following structure to our Sprint names:
< Sprint > < Year > < Month > < (Version) >
The "(Version)" is optional because even if we do monthly sprints we do a Release every 3 Months. In this case 3 Sprints might belong to one Release.
If it would help, you could also use the Sprint Goal or product name.
I don't use the goal or product name because my Sprints belong to a product and that's already mapped in the system.
Answer: We just started new sprint naming type that looks like 'YYYY-QX-X/6'.
2018-Q4-5/6.
We are setting quarterly team goals. This naming type makes feel a deadline.
Answer: I think a "common name" in parens behind whatever non-memorable number system you use is fine and beneficial, if not fun. They could even correlate to the number.
before: 2021W31
after:  2021W31(Reggie)
Answer: Do not name the sprints in Scrum, it is pointless!
What's the value in doing so? NONE
Is the Scrum guide recommending it or somewhat suggesting it? NO
Is it part of any artifact? NO
Sprints have names because bloody Jira added that functionality, but certainly and to avoid confusion, the sprint name must be autogenerated, 1, 2, 3, etc...
The important information about the sprint is already part of it and once is finished, that information still persisted, like the goal, length, start date, end date, etc...
If I want to find a sprint I would do it either by starting date or goal. Ultimately, we can check a task of which, the sprint interest us and check the Sprints field (in Jira), and you can find it...
Neither the Product owner, the scrum master nor the developers, anyone cares about the name of the Sprint... ONLY JIRA DOES!
Comment: I disagree.  It's often useful, e.g. in retrospectives to make comparisons with previous completed sprints (e.g. "velocity is slightly higher than it was in Sprint 4").  Without any names, it's awkward to do so, and increases the risk of miscommunication.

How do you name Sprints in Scrum?


Student Visa in Spain

Question: I have a student visa in Spain, which will expire in a few months.  I want to come back to the US for a few months and then return to Spain to continue my studies.  Do I need to start all over, or can I extend my visa for another year?  Is it a problem if I leave Spain for 2-3 months and then return?
Answer: You should consider what you would need to do if you were not planning to leave Spain.  In that case, you would most likely need to get a residence permit (unless you already have one).  If you already have a residence permit, it replaces your visa, and you can use it to travel out of Spain and back, as well as all over the Schengen area.
If you leave Spain, you will probably need a valid visa or residence permit to return.  If you find yourself outside the Schengen area with no valid visa or residence permit, then you will probably need to apply for a new visa.
I say "probably" because I assume from "back to the US" that you are a US citizen.  some Schengen countries allow US citizens to apply for residence permits without first obtaining a long-stay visa.  If that is true in Spain, you might be able to enter as a visa-free visitor and then apply for a residence permit.  But be certain of that before you attempt it.
The best course of action, if your circumstances qualify for it, is to apply for a residence permit before you leave Spain.
Comment: and inform them  that you will be visiting home for 2-3 months during that time.

Student Visa in Spain


Adobe Premiere Pro Rendering in Linux

Question: I was really wanting to build a Raspberry Pi Linux Cluster (~20GB RAM, etc). I was wondering if it would be possible to render video from Adobe Premiere Pro to Linux and how I would incorporate a rendering farm to split up the tasks. Thanks for all of your help!
Answer: At the moment, Adobe Premiere Pro struggles to run properly on the systems it supports--Windows 10 and Mac OS 10.10.  As of today, Adobe does not even recommend running it on Mac OS 10.11!  Premiere Pro does not run at all on Linux, and while you might be able to create some virtualized environment that can host a cluster of OSX or Windows instances on a Linux cluster, such virtualized environments are weakest where Premiere Pro needs them to be strongest: at the CPU/GPU interface.  In summary, not today, and likely not in the near future.
A far better starting place for your cluster project would be to select an open source video editor (here's a snapshot of the state of the art for 2015) and evaluate what sort of Raspberry Pi cluster is needed to compete with a typical modern GPU.

Adobe Premiere Pro Rendering in Linux


Android: Netrunner judge program

Question: Does Android: Netrunner have anything similar to Magic the Gathering's judge program?
Answer: Fantasy Flight Games doesn't currently have a judge program, the closest thing they have are the floor rules.
However at the start of 2015 they announced their intent to setup something like a judge program sometime this year, with a trial starting in the US initially.
It's possible they're delaying the program to see what happens with the Magic Judge system after the currently running lawsuits are settled.
Comment: Did anything ever happen with this in terms of a judge program being instigated for Netrunner?

Android: Netrunner judge program


Great companies using FPA as cost estimation

Question: Anyone know if great enterprises (Google, Oracle, SAP) uses Functional Point Analysis to estimate software building effort?
Comment: Since you're Brazilian too, Petrobras used to employ FBA as a cost estimation tool. I'm not sure it still does.
Answer: The IFPUG Membership Survey will tell you a little bit. Still, when I see a company like "IBM" in that survey, I am guessing it is Global Services (their consultancy). Maybe some product teams use it but most of the members of this organization at least are consultants / service providers who are selling The Methodology along with Their Services.
Answer: I worked for a fairly good-sized pharmaceutical company that used it, but that's the only time I've seen or heard of it used.  It seemed like a reasonable methodology to me, but rather time-consuming and probably expensive (the guy who analyzed my systems was an external IFPUG-certified consultant).


Cooking over an open flame at home

Question: Is it doable to cook over the flame of a cooking gas stove at home. Is it dangerous? Couldn't it be even better as an open fire over coal or wood, since gas is cleaner?
Comment: Are you talking about doing this inside?
Comment: @KatieK yes. but now I am more worried about the cleaning.
Comment: By "healthy" I assume you mean "will the smoke kill me". Other than that there is nothing healthy about open flame cooking of any method
Comment: related : http://cooking.stackexchange.com/q/10588/67
Comment: Hello Quora Feans, "healthy" is off topic on our site. I've heard of long term concerns of exposure to open fire due to all the exotic carbon compounds produced in combustion, but if this is what you mean, you'll have to ask your questions elsewhere, we cannot answer it. We do handle the immediate safety of cooking though (e.g. will the gas explode or leak and suffocate you), so I edited the "healthy" part out and left the rest.
Comment: @TFD billions of people do nothing else all their lives... I'd rather cook all my life over an open fire than be dependent on a microwave for all my cooking...
Comment: @jwenting Who said anything about the microwave? Billions of people rely on open flame cooking through little choice, and millions of children die young from the fumes
Comment: I use it to char a pepper but I that is not what really cooking
Answer: It is similar to cooking over a propane grill. Gas grills often have stone or ceramic bricks in them to help retain heat, but it is the burning gas that provides it.  Cooking over a gas stove should be similar.
That said, I wouldn't grill meat or fish directly over the flame; it may work, but the cleanup may not be worth it.  If you want to char a pepper or some bread and get the 'grill' feel, that should work fine.  I see chefs do it all the time on TV, and it looks easy enough and doesn't make a mess.
Answer: Any fire in a confined area with limited ventilation, that produces smoke (an unburnt solid) is a health hazard, particularly those the with lung disease or asthma.
Answer: I'm really into preparing "meze" dishes, a class of dishes in the Turkish kitchen. A lot of them are prepared charred vegetables such as aubergines and peppers. These are traditionally cooked over a charcoal grill, but in many a Turkish home, they are cooked over the open gas flame of a modern stove top. The aubergine, after being charred, is put into a vessel of cold water, the charred skin being removed to reveal the cooked flesh with a wonderful smokey taste.
On the health side, I can only give anecdotes. My grandmother has prepared these dishes over the open flame for as long as I can remember, and no doubt, a few multiples of that length of time more. Personally, I've been preparing these dishes since I was 16, with no ill effects to speak of. A small amount of smoke does arise from the burning of the skin, but the vegetables themselves don't burn. If your kitchen is properly ventilated, can it really be much worse than going out into the typically densely populated modern city?
Answer: I cook hot dogs and fire roast peppers, directly over my natural gas stove indoors. Its the best way in my opinion. No mess, no fuss, just good eatin'
Answer: Why do you think gas is "cleaner". It contains CO2, CO, and other petrochem processing leftovers
Good quality charcoal should produce the least other stuff, while producing similar CO2 and CO levels
Indoor cooking with charcoal is popular in many cultures, but any method is going to produce CO2 and CO, which need to be adequately ventilated
Comment: Under perfectly ideal conditions, neither gas (methane, CH4) nor charcoal (pure carbon) should result in any dangerous byproducts (apart from CO2). However, this is impossible to achieve in practice. I would imagine that ideal combustion of charcoal would be more difficult to do than gas - if nothing else, it would be harder to mix the fuel with oxygen in a maximally efficient manner, and you would likely end up with lots of dangerous CO (this is a product of incomplete combustion, not present in the gas itself) and probably various carcinogenic hydrocarbons and particulates as well.
Answer: If you have a concrete slab or sand box to cook on. In home or out. A pot stove is very good to cook on. You cut a hole in the pot at the bottom. Just at the top bottom of a cast pot. Cut a square 3 by3 inches or larger in md size to large pot. This is to feed your small wood or charcoal threw. Light. Get burning. Place rack on top of pot. Next a pot or skillet to cook in. You control heat by adding more sticks or charcoal or pulling some out. This forces most heat strait up. So saves wood or charcoal in cooking. This is the main way of cooking in my part of S.E.Asia.  Bottle gas stoves are safe. Just remember to turn of the gas at the bottle.  Here those who can afford such. Normally buy a 2 burner & stove cart Glass top to set it on. Storage on shelf below. 5lb bottle but a 20 is also used. Space is important here. A cart has wheels so is easy to be moved out of way. For living space after use. A singles pad would have a 1 burner stove. You may see some at imgur under jamesphilippnes.  You need a vent hole to cook on wood or charcoal inside. Why most have a dirty kitchen outside or a T home here.
Comment: An unvented indoor charcoal fire is a great source of carbon monoxide, which You Don't Want. Wood isn't a whole lot better. Be safe!

Cooking over an open flame at home


How did Cobb and Mal commit suicide while young in limbo if they lived decades there?

Question: We can see the scene in Inception where Cobb and Mal commit suicide on the train tracks at a young age, but in the end of the movie Cobb reminds Mal that they lived to a very old age in their dream. How is this possible? Or was the suicide scene just a representation?
Answer: Likely the latter: An 'unreliable' representation of what happened. Since that crucial bit of information (that they grew old together) is still left out as Cobb and Mal go over what happened to them in Limbo, this is either Cobb or Mal (or even Ariadne, representing the viewers) imagining they were young there or falsely remembering it. Note that some of the same scenes of them in Limbo (strolling through it holding hands, and their hands on the train tracks) are later reconstructed with their old selves after this bit of dialogue:

Mal: You said you dreamt that we'll grow old together.
Cobb: But we did. We did, you don't remember?

So this is basically a case of a detail left out for the impact of a later reveal; since we don't know it yet, it's not yet visualized - with the possible in-universe excuse that someone is imagining it that way.
Answer: The imagery for limbo is a bit confusing, especially when you factor in Sato's appearance when Cobb finally shows up.
That said, however, when they do kill themselves they ARE old, or at least they think they are.  I think not making them appear old was a visual inconsistency, but it may have been intentionally made by Nolan to make the whole suicide scene and after more confusing and less clear-cut.


How do I reclaim the "other" space on my iPad?

Question: I have 3.3 gigs of space in the "other" category on my 16 gig iPad. The space for "other" has grown over time.
I've synced. I've powered down. I've turned all running apps off.
How do I reclaim this used space that I'm not using?
Answer: The "Other" space is not necessarily unused as you imply.  It could simply be your user data from your applications.
If you check in Settings > General > Usage you can gauge how much space your apps are using up including their data (might be photos, or podcasts, or pictures, or anything).
For example, my Instacast it taking up 406Mb of space, but the application is only 3.3Mb.  So that's over 400Mb of "other" space taken up right there:

If you were to add up your the data in this list, then subtract the total amount of "application" usage from it, it should pretty much equate to the bulk of this "other" data.  Of course, there are other things that are included as "Other", including your mail data, sms messages, internal log files and location data stores etc etc etc which may fluctuate over time but the big portion is just your apps contents.
Comment: On my 16 GB iPad, my total used adds up to under 6GB, yet it reports over 9GB being used. That usage section definitely don't paint a full picture.
Comment: This answer makes sense. However, it seems on my iPad I am paying a memory price twice for my music. That is, the Music app uses 10.9G in the `Usage` screen, *and* iTunes says my iPad has got 8.81G in audio (blue bar). Any ideas?
Comment: This problem seemed to go away when I synced with a USB cable, as opposed to syncing over the network. I think something got out of whack after the iOS 7.1+ update.
Answer: I had the same issue - 2 GB "other" space that I couldn't attribute to anything. After seeing Martin's thought I decided to try installing the iOS 6 update, even though I didn't want to. That did the trick, cleared up 1.8 GB.
Ideally Apple would provide an easier way to reclaim "other" space.
Answer: This problem was driving me crazy. I tried everything suggested on numerous websites and forums, until I finally realized what had happened. I installed the programs sugested by many and searched for this other space that was referenced. I couldn't find much, and it was really frustrating. I finally just rebooted it and cleared all the space, so... if you haven't tried rebooting your iPad/iPhone do that.
Answer: I've just been through the process of finding out what is included in "Other" and clearing it on my iPod Touch (4th Gen, iOS 5), so I believe the following should apply to the iPad as well.
I had 2.3GB in the Other section as reported by the iTunes bar. This does not include the data within the apps, they are shown as the App section of the iTunes bar and itemised as shown in stuffe's post. The majority of it (2.2GB) was pictures and video taken using the camera, still in the Photos app in Camera Roll. I found that out using DiskAid, which allows you to copy them to your PC/Mac. Right click and Get Info on folders in DiskAid shows you how big each one is. Note that the Photos section of the iTunes bar seems to include the other albums but not the Camera Roll.
I tried this answer, removing the F folders, but it didn't save that much memory for me (about 0.1GB), you may get better results.
A lot of people seem to be saying it's the Mail app, log files, bookmarks, notes, calendar appointments, reminders etc but this doesn't seem to add up to gigabytes.
Another thought - it appears that iOS 6 has downloaded without my permission, which would be a rather large file. As soon as the badge on Settings appeared, I noticed that it gave me the option to download and install. Until the Maps issue is resolved, I don't intend to upgrade, so I definitely haven't given it permission, but now it simply says Install Now.
Answer: Shut down the ipad completely, restart it sync and you get the free space. Strange but it works. I had 25gb in my other
Answer: I tried to change the movies on my ipad 2, deleting 3 and adding a new 3 at the same time. The sizes were ok so it should have been able to fit easily. The delete happened but I did not get the space recovered. My Other category swelled.
Re-syncing failed then I found powering off then on solved my problem, "other" went to a normal amount and then I was able to add my movies, I think this is rediculous but it just adds to the "others" mystery.
Answer: I used DiskAid, went to Media - PhotoData - Thumbnails and deleted everything in the folder. I reclaimed 1.76GB or 3.53GB.
Comment: Can you please add a link to the app?
Answer: This happens to me every three or four syncs.  "Other" mushrooms to 3-4 gigs.  The solution I use is to disconnect the iPad from the PC.  Hard power down.  Wait 10 or more seconds.  Repower up the iPad and then sync.  It works about 95% of the time.


Does "Google Webmaster Tools" service send notification if finds broken links?

Question: Can GWT email me if a broken link is found on my website?
Answer: No, not for single broken links. It will, however, notify you of large and sudden changes; for example spikes in the number of 404s, soft 404s, server errors, etc.
Your best bet is to periodically check your site with a crawler like Xenu or Screaming Frog.
Answer: Google Webmaster will only email you if it finds critical issues with your site.
For example, it will email you if it detect malware on your site or see a significant increase in errors while crawling your site.
They recently announced this via their blog: http://googlewebmastercentral.blogspot.com/2012/10/keeping-you-informed-of-critical.html
You can change some of those notifications by going to your email notification preferences.
https://www.google.com/webmasters/tools/preferences


Merge tags software and software-rec?

Question: There are now questions tagged software and software-rec. All software questions look like they're software recommendations and should be tagged software-rec for compatibility with Super User. I'm not sure whether software should be a synonym of software-rec or if it has some independent legitimate use here (in which case the questions should be retagged).
Answer: All the software posts do seem to be recommendations, except for List installed packages in Fedora. I dropped the tag from that one and merged software → software-rec:

updating post history, 8 rows affected
  updating posts, 7 rows affected
  updating PostTags associations, 7 rows affected
  removing/renaming old tag, 1 rows affected
  updating count for master tag, 1 rows affected
  merge of [software-rec] and [software] complete!

I'm not sure if it should be a synonym or not, so I didn't make one for now
Answer: I can't imagine a question that should be tagged software and not software-rec. It makes sense for E&R, but not here. Since this is a Unix & Linux site, all questions relate somewhat to software - it's a given.
Comment: I just retagged http://unix.stackexchange.com/questions/3322/what-makes-osx-programs-not-runnable-on-linux then wondered if `software` hadn't been a legitimate tag after all.
Comment: @Gilles That does seem like a rare legitimate usage, but the tag itself isn't particularly helpful; nobody's going to search for all [software] posts

Merge tags software and software-rec?


What are the audio equivalents of images like "Lena", "Mandrill", and "Cameraman"?

Question: I don't know what to call these images, but they're very often used in the image processing world as standard examples to show the output of a particular operation. Here's a link to the page describing Lena as a "standard test image". Are there similar canonical audio clips used to demonstrate the effects of certain audio filters or operations?
Answer: The closest example I can think of is the beginning of Suzanne Vega's "Tom's Diner" which has been used for the mpeg-1 layer 3 development, and is still occasionally used to demo audio codecs.
Comment: yah, Tom's Diner is a reasonably clean (reverb free) and monophonic singing voice snippet that is useful for testing pitch detection programs.  another one is a Boyz II Men clip offa their cover of the Beatles' "Yesterday" (right at the very end).  good for pitch tracking of a monophonic vocal.  it's tougher than Tom's Diner.  i remember Digital Performer used it.
Answer: Audio processing is a large field, but specifically in speech processing, an open database of samples known as Harvard Sentences is widely used. Harvard sentences are phonetically balanced collections of sentences in American English. Many equivalent databases exist for other languages as well.
Actual files with Harvard Sentences speech can be found here.
Answer: I also think that NIST database is very popular when it comes to speech recognition tasks. In fact it is a standard for comparison of new algorithms and techniques during yearly challenges.
Additionally MATLAB's load handel containing snippet of G.F.Handel - Hallelujah is quite commonly used.
Answer: The European Broadcasting Union's (EBU) Sound Quality Assessment Material (SQAM) resource is pretty popular. https://tech.ebu.ch/publications/sqamcd
Answer: Do not underestimate the power of 1 kHz sine wave at 0 dBFS. In mono. A lot of things that are wrong with signal paths can be found with that.
I've built and calibrated enough audio systems that I can whistle 1 kHz pretty exactly. From simple memory.
Other than that, I.G.Y by Donald Fagen is so popular as test track that it's been forbidden by a number of festivals.