People are so used to programs loading instantly on modern hardware that they forget that it used to be normal to wait a good 30 seconds for a typical program to load
Yes, they forgot the DOS days, and they are happy about that. Why in the world they'd go back if they don't have to?
think that waiting 2-3 seconds for a program to load is a crime against humanity.
I have a reasonably fast Vista notebook (Windows score 4.2.) MS Word 2003 starts in... let me measure... 4 seconds, and I can start typing. OpenOffice starts in... let me measure... in 25 seconds. Now, 5x difference is a major one, and this notebook has 2 GB of RAM (a netbook may have less than that - RAM eats power.)
Although I am on record for online applications, and I am a big supporter for the idea however there are some software that can be online apps but shouldn't.
Also people work with many documents that shouldn't ever be uploaded onto servers that someone else controls. That can be company documents or just your financial data, or anything else you don't want revealed. If you are really concerned, you can install full disk encryption. But that will do nothing for safety of documents "in the cloud" .
I make an actual voice call maybe once a week, so it's one of the least important features for me
I agree - ability to MAKE the call is not that important because you are in control and you can find an alternate way or time to call someone.
The most important purpose of a cell phone is to RECEIVE calls. You can't control incoming calls, so your phone must be always ready to accept them. Some calls may be even important.
I understand what you are saying, but I think investors into *this kind* of venture are smart enough to ask for the calculations before they will want to see pictures. Ask for the specific impulse and see crazies wither and disappear.
Besides, if they haven't calculated the weight, size and shape of their vehicle, may I ask what exactly they are going to render? Something they remember from Star Wars, or from cover pages of Amazing Stories?
The "render first, make later" approach works only when your product is technically simple, but is unique in its shape or form. Watches and cell phones are the prime example.
A lot of you seem really quite pessimistic, which is somewhat depressing tbh.
That's because they seem to approach the problem as amateurs, in the worst meaning of the word. Here, in the brackets below, is the entire drawing that they need for first 300 pages of math and sketches:
[.]
They need only that much of detail to define the vehicle, select engines, determine weight limits, and so on. Once that dot "flies" in math, only then you might want to look at it closer.
If they work on robotics and such, a proper CAD is even more relevant because you can have parts made right after you designed the assembly, and you can put your robot together a week or two after that. No, this whole mess with "graphic artists" and F/OSS CAD is just a mess. Or at least the OP presented it as such. Maybe it's just a live demo of why only certain officers of a company, and not any random engineer who wants to, should talk to the press.
And you are suggesting to do stress and vibration analysis with that software? (none of the ones you list have any calculation quality beyond a fast and dirt check).
I don't suggest anything, I tell you what I use. There is a difference. What I use is suitable for my projects, and I don't design flight hardware. If you do, please make your own choices.
If you are curious, last time I used FloTherm for thermal/airflow simulations, Ansys Workbench for stress/deformation, and NASTRAN for vibration. Those are pure FEA packages that the company has licenses for. I use Cosmos tools and the little stress module in Inventor mainly for quick-and-dirty checks. There are many tools out there, and the designer should know what to use and when.
Yes, both things are something that I wanted to mention but it was too late.
It does make sense for a company to *add* something to the existing package if they think it is a good idea. Modern CADs allow easy addition of 3rd party applications to the system, so that they have access to the models and can do things. There is a good number of 3rd party add-ons for SolidWorks, for example. Your suggestion of refining "one thing" is very valid.
Outside of that, I do not know if Armadillo programmers' gaming experience fits well into the needs of a FEA. In games you need an approximate answer; an error within 10% would be invisible to the user. But you need the answer very fast. Gaming engine's physics module satisfies those requirements; you may need only integer math to get close enough. But in FEA modeling errors accumulate and propagate; they can lead to failure to converge when by all indications it should. So it is a matter of considerable concern, managing accuracy, precision and the size of the data (it's usually huge already.) SMP is typically supported by all modelers; some, like CST, support clusters. This is yet another thing that games don't need to worry about.
Also, NASA has lots of code specifically written for spacecraft simulation, and I'm sure Armadillo can get access to that - for use or for improvements as needed (and it is badly needed in some cases, the code is old.)
Your comment makes me wonder what Armadillo Aerospace could come up with (in software) for their own designs
This is not a new problem, really. What a startup didn't hear such a great idea from a young, enthusiastic engineer? "Boss, don't buy Quickbooks, don't waste $150, I will write the stuff for you for free!" If the boss doesn't know any better, such a proposition is usually a total loss. (Just have a look at QuickBooks for the proof.)
There are at least two issues at work here. First, do you have an expertise? And second, will your resources be better spent on something else, new perhaps, instead of reinventing the wheel?
As major CADs go, a mere $20K for a full SolidWorks seat is peanuts. Most of the labor that goes into the software is spent on interfaces; the rest is in licensed, very specialized libraries that do their job. For example, most 3D CADs use 3rd party math libraries that calculate all the solids and do all the heavy lifting. Simulation is very frequently done with 3rd party tools also, just because it's so hard to do fast. Ansys licenses their solvers to Autodesk, IIRC, as well as sells them independently (Ansys Workbench.) Then you go into the flow modeling (liquid, gas) and thermal modeling (in everything) - those represent yet another unique problem. The equations that describe the model are pretty well known; the real challenge is to simplify the model enough so that the computation ends before you die from old age, and at the same time retains enough accuracy. Meshers are a popular, very complex problem, most FEA tools have several adaptive meshes, and a lot of effort goes into building them.
All that takes an awful amount of time and resources. Armadillo probably doesn't have enough expertise to code most of the hard stuff. Sure they can do GUI, but that's the easy part. They'd need probably a few decades, given their limited workforce, to recreate the existing software, and that would cost them a lot, and they'd be making no progress on the rocket, and they'd be getting no grants for any of that. Unless they want to enter the market of simulation tools, they'd be better off working on their main goals, and paying pocket change for access to missing knowledge and skills (in form of simulation software, or consultants, or whatever.)
Keyfobs allow you to use the car without ever removing them from the pocket or a bag.
Mechanical keys are dangerous too; apparently in some cars if you turn the key back one click too many the steering will lock. You probably don't want that at 65 mph.
The damned foot pedal brake is extremely uncommon here
When the parking brake is engaged there is a red indicator among instruments, it says BRAKE.
I'm sure your aunt would be just as much confused if she drove cars with an on/off button all her life, but this weird car has a key, like a house key, and you need to do something non-trivial with it!
Ok, let me explain. Either you buy an excellent 3D drafting / modeling software, or you spend 1,000x that much on paper analyses done by PhDs and on testing of real parts done at ranges and in test flights. The latter approach was used for Moon rockets - cost was no object. Those guys are welcome to borrow $100B and do the same; or they can borrow $100-200K and buy the best tools that are available today. But using play-do for things that life depends on is, IMO, beyond silly. I'd call it criminal, though as someone else already said they have no chance to even get to the point where they can kill someone with their rockets.
I do mechanical design and simulations, by the way, in SolidWorks/CosmosWorks, in Inventor, and with CoCreate/Nastran tools. Probably more. So I know a thing or two about this.
I looked briefly at the FreeCAD, it is impressive for a F/OSS project but I'm afraid it's not good enough yet to even make a plastic case for yer cell phone, let alone a propellant tank. For example:
There is no "Assembly" workbench with its numerous constraints.
I don't see auxiliary geometry, such as work planes, axes and points.
I don't see projected contours and relations between parts. That's a super-major hole.
The list of features that can be created is quite basic. Professional CADs (SolidWorks, Inventor, SolidEdge, ProE) have lots more, and you need them.
There is no pipe and harness workbench, sheet metal workbench, molds, gears, kinematic, stress, thermal, vibration - you name them they don't have them. You'd think stress and vibration are optional on a rocket?
The OP asked "what free s/w to use to build hardware to fly to the moon." My answer would be: "it doesn't matter, it won't work anyway." If I were to do the whole project, I would be first concerned about financing the whole project; cost of the best software on the market would be a drop in the ocean compared to everything else. People who started the moon project with a predetermined opinion what tools they will use won't get anywhere, not in the rocket science at least.
We have absolutely no evidence that FTL travel or communication is possible.
Absence of evidence != evidence of absence.
Our theories of Physics do not predict the possibility of FTL travel.
They don't predict many things. Our theories are incomplete, full of major assumptions, and still there are so many of them. The hope is that LHC will weed some out by proving them wrong. But we are not yet at the stage where we can definitively proclaim that FTL travel or messaging is impossible. Near-instant communication that we enjoy today would be a preposterous impossibility to a medieval king because no horse can run that fast.
Today we have theories that challenge some foundations. For example, this paper points out that if the speed of gravity were to be limited to 1c then our Solar system (just as all other) would spiral into the Sun pretty fast. It turns out, orbital mechanics calculations use infinite speed of gravity, and Pluto always "knows" exactly and instantly where the Sun is - not where it used to be hours ago. This is a very interesting paper.
Merely getting from there to here would consume so much energy
An ideal round trip in a potential field consumes zero energy. A pendulum can swing for a very long time, limited only by losses in the thread. Our rockets consume a lot of energy just because they are so incredibly inefficient.
About slow communications. I am indeed pessimistic about prospects of communicating if FTL messaging is proven to be impossible. There would be very little reason for dissimilar civilizations to spend vast resources on talking over light years and centuries of round trip time. If you want to ask "do you have antigravity?" it will require you a millennium to establish the dictionary, then ask the question and then to receive a response. Probably by that time you could figure it out yourself. And the answer would be probably already superceded by the newest research done at either end.
You do mention the continuous streaming of knowledge, and that might work, but it depends on willingness to spend considerable energy on an exchange that you will gain little out of (if you are an advanced civ.) Earth has nothing to say, except basics of our life.
Xenophobia is misplaced in this situation.
I only described concerns that would be valid if we encountered a version of our own civilization. To dismiss those concerns you need to show that our civilization is unusually violent and bloodthirsty. And I see nothing particularly unusual in how we developed so far. At every moment of our history our civilization was acting pretty logically for their time. There was no divine enlightenment, for example, no black monolith with 1x4x9 proportions - we arose from animals by just being more violent and more smart, and taking our time.
A cube farm usually has power, phone and Ethernet coming into each cube. Ethernet is usually routed from a switch somewhere in the back room. The link is very simple, and if it fails you just test the cable with a pocket tester or replace the switch.
Use of optical LAN may require *more* wiring, not less, depending on how many APs you need, and AP's cables have to climb walls if that's where your lasers are. You also need to feed power to them somehow, using PoE or from wall sockets. If something goes wrong you have several possible reasons, and the investigation will take longer, and it will be not as easy to replace a laser AP that is on the ceiling or high on the wall. Some faults can be caused by shadows, people passing by, and other problems that Ethernet is free of.
Leakage to other areas is not affected (unless you talk WiFi which isn't that popular in cube farms) because there are cables that go to laser APs anyway. The 1 Gbps speed is already provided over CAT6 Ethernet, and even if you push it to 10 Gbps somehow it won't make any difference because your SharePoint server still takes 10 seconds to display a page, and your Exchange server still takes minutes to "synchronize folders" because it is obviously such a monumental job.
Considering the cost of laser APs, and of their counterparts in each computer, and additional wiring, and additional complexity, a simple Ethernet cable laid by a lowly tech once, working forever and requiring no power, looks like a great deal.
I think it's safe to assume that point (1) is correct. We know very little about how interstellar travel will be conducted, but we do know that the energy cost of moving things between stars is extremely high.
The energy cost of a round trip is zero, unless your spaceship has friction against ether, or something. Besides, even if you use more wasteful ships, an advanced civilization is supposed to be able to afford their use if they make them in the first place.
As for point (2), Earth is nothing special.
You offer many guesses, but miss the one that several posters already mentioned. The aliens may want to simply destroy us as future competitors. They indeed don't need us or our planet or anything in between. They might just want us gone, like you want mice gone from your home. Just a guess, of course, but it has its place among others. And don't forget the hyperspace bypass theory too.
considering the cost of interstellar travel, any civilisation that makes a habit of sending ships to other worlds for the sole purpose of killing aliens isn't going to last very long.
You may be right, and when Earth starts shaking and falling apart under their destructor beams we should be sure that those aliens won't outlive us by much - a few million years, top.
I just love how everyone on Slashdot thinks that they know what some alien race is thinking, as if they themselves were from some alien race and have the key to their rationale.
One of those keys is indeed available to us; it's called "logic." Logic should be, to our best knowledge, universal across this Universe and it applies to all species equally. When we say that "civ. A may be worried that civ. B is hostile" this is just a statement of logic and has nothing to do with either civ. - unless the A is totally incapable of comprehending the word "hostile". And to that I find it unlikely that a civ. can sail all the way to the "advanced" stage without encountering opposition, be it from nature or from sentient things.
Logic is the foundation for math, and math is the foundation for science. A civilization can't become advanced without being well acquainted with logic. Therefore when faced with a problem of logic they will solve it just like we, or other civ. would do, given the inputs are the same or at least understood as variables.
You should put away your absolutes and your thoughts that 'humanity is superior', because we have no evidence to either.
Humanity, as matter of fact, is superior to animal kingdom. Historically, many groups of humans were superior to other groups. We know well how that works between humans. If we extrapolate this behavior onto other civilizations we always claim that it's a mere guess. But there is no law against guessing. Lacking more information, it is perfectly valid to presume (for some purposes) that aliens are just like us, because we have one sample of such species right here (and we have no samples of other, theorized species.)
We are so ignorant and arrogant that we expect other civilizations to think and act exactly like us [...] so they must be truculent and violent like we are
It is not unreasonable as a first guess. We are violent because it is our survival mechanism. Top predators have few offspring, they can't afford large losses. Rabbits multiply like rabbits, they depend on that instead of their teeth and claws.
The question is really when (or whether) the society transitions from violent survival mode to relaxed, peaceful mode. That's not easy to answer because our behavior is coded in our genes. Some civilizations, like Klingons, may even cherish this trait. We don't know how likely it is, but the one sample we have - ourselves - tells us that it's not an easy answer. And we can't even say that we are unique in our violent roots - there doesn't seem to be anything unnatural in what we do and how we ended up this way.
However when connected to 3-phase power there are always two lights that are on for every one that is off.
Also when discussing street lights, it's practical to note that the lights shine down, not up. Only the light that is reflected by dark, gray asphalt, or grass, or trees (10% maybe?) escapes into space. An alien astronomer could write it off as lava flows from volcanos, given the spectrum of HPS lights.
what value would we get out of colonizing the moon. Or Venus or Mars? [...] We can't even bring ourselves to build reasonable colonies underwater on earth, or at the south pole
There are plenty of people who would be glad to leave their tyrannical states and go somewhere else, to create another state of their own, not as corrupt yet.
But there is no free place on Earth to do that. All usable land belongs to someone. Antarctica is so harsh and inhospitable that it probably rivals the Moon (get out without a suit and you die.) There is far more economic advantage to have a city on the Moon than in Antarctica.
Creating such a state under the sea is definitely a possibility, but it's quite expensive. Probably cheaper than doing the same on the Moon, but they both are orders of magnitude more costly than a bunch of wannabe settlers can collect. Eventually, though, underwater cities will be built - it makes plenty of sense; there are natural resources in oceans, and many people are used to living in steel (stone) caves already, so what's the difference? A city a mile underwater is also very safe from weather, and can be built to tolerate large earthquakes by making the buildings sufficiently light; if their supports fail they simply slowly drift some 100' to the bottom instead of crashing hard. Such a city is also safe from asteroids striking the planet.
technology is not going to allow us to circumvent the speed of light.
That can be said only if you have the Complete Theory of Everything in your posession. Besides, the 'c' limit is valid (if it is) in this Universe; we don't know that about other Universes. For example:
In the first 1E-35 seconds (that is 0.00..(34
zeroes)..01 seconds after the big bang the universe expanded to a diameter
of something like 1 meter carrying all matter with it. So it was expanding
something like 3E26 (that is 3 followed by 26 zeroes) times faster than the
speed of light! (link)
That is because the space itself expanded faster than light. Find a way to create (and destroy) space at will and you have FTL. This, actually, had been proposed many decades ago by at least one SF writer.
Intergalactic travel is too energy-expensive to be a reasonable solution for any of the scenarios you outline.
I'm sure something like that was said to Columbus:
On 1 May 1486, permission having been granted, Columbus presented his plans to Queen Isabella, who, in turn, referred it to a committee. After the passing of much time, these savants of Spain, like their counterparts in Portugal, reported back that Columbus had judged the distance to Asia much too short. They pronounced the idea impractical, and advised their Royal Highnesses to pass on the proposed venture.
In 15th century a trip to Asia/Americas was too expensive for a king (and they were wrong about that too.) In 20th century a trip to Asia/Americas is cheap enough so that any working person can afford it. I wouldn't dare to opine about costs of future intergalactic trips.
Ships that would either whizz right by you, crash into you at relativistic speeds (with presumably fatal results), or have to spend most of their payload capacity decelerating before they got to you.
I see that you are not a Cosmic Engineer then. I would catch the incoming ship with some force field and recover all its kinetic energy while slowing it down. Remember, an advanced civilization, who builds a Dyson Sphere, is not necessarily limited to kerosene+LOX rockets.
You presuppose that an advanced civilisation would not deliberately broadcast radio signals for others to detect?
I'd expect it to NOT broadcast. There is one simple reason - you never know who is going to receive those signals. Are you willing to bet the existence of your civilization on the theory that all civilizations are peaceful? We are the proof of the opposite.
a very advanced civilisation would realise that radio technology is cheap and simple
... and that the radio propagates with just the light speed. Which means by the time they receive the signal that "young" civilization can already have FTL ships and be knocking on their doors, with peace or with war in mind. That's hardly smart if you have FTL yourself. An advanced civilization can afford to send a probe into many star systems; these probes then can do monitoring and reporting by FTL channels. Further observers can be always sent if necessary.
I'm sure they might do some deliberate broadcasting of their own towards likely stars, in the hope ob being detected.
Why would an advanced civilization "hope" that a young one developed tools to receive those signals? What is the benefit? The older civilization gains nothing, other than a new article in their Encyclopedia Galactica. The younger civilization, having no FTL, will probably go crazy. You can't maintain a dialog over the radio on the scale of the galaxy, the radio is too slow for that. Imagine that we received today a message from the stars, and the message says "Hi!" - what will happen to the world? And I'm very much unsure that the older civilization will be quick to send us the FTL formulas; likely it will require a lot of science before we can understand them, and without the common language it's hard to achieve. But the older civilization must also consider that we can receive and understand FTL, and then immediately make a weapon out of it. Knowing earthlings, it's a certainty.
As I mentioned earlier, the only sane way to use radio would be for the older civilization to monitor the stars (using probes or listening directly from their homeworld.) Once signals are received, an FTL ship with scientists should be sent to that star system to investigate and decide if the new one can be trusted with the contact.
Slashdot Mirror
People are so used to programs loading instantly on modern hardware that they forget that it used to be normal to wait a good 30 seconds for a typical program to load
Yes, they forgot the DOS days, and they are happy about that. Why in the world they'd go back if they don't have to?
think that waiting 2-3 seconds for a program to load is a crime against humanity.
I have a reasonably fast Vista notebook (Windows score 4.2.) MS Word 2003 starts in ... let me measure ... 4 seconds, and I can start typing. OpenOffice starts in ... let me measure ... in 25 seconds. Now, 5x difference is a major one, and this notebook has 2 GB of RAM (a netbook may have less than that - RAM eats power.)
Although I am on record for online applications, and I am a big supporter for the idea however there are some software that can be online apps but shouldn't.
Also people work with many documents that shouldn't ever be uploaded onto servers that someone else controls. That can be company documents or just your financial data, or anything else you don't want revealed. If you are really concerned, you can install full disk encryption. But that will do nothing for safety of documents "in the cloud" .
would you have preferred them to have rejected the app outright instead?
An outright, written rejection on the grounds of mentioning the competition may be seen by lawyers as grounds for a lawsuit.
I make an actual voice call maybe once a week, so it's one of the least important features for me
I agree - ability to MAKE the call is not that important because you are in control and you can find an alternate way or time to call someone.
The most important purpose of a cell phone is to RECEIVE calls. You can't control incoming calls, so your phone must be always ready to accept them. Some calls may be even important.
I understand what you are saying, but I think investors into *this kind* of venture are smart enough to ask for the calculations before they will want to see pictures. Ask for the specific impulse and see crazies wither and disappear.
Besides, if they haven't calculated the weight, size and shape of their vehicle, may I ask what exactly they are going to render? Something they remember from Star Wars, or from cover pages of Amazing Stories?
The "render first, make later" approach works only when your product is technically simple, but is unique in its shape or form. Watches and cell phones are the prime example.
Brake ! = Park Brake
I'm not aware of any car on the market (or near it) that has an indicator that lights up when you press on the brake pedal.
A lot of you seem really quite pessimistic, which is somewhat depressing tbh.
That's because they seem to approach the problem as amateurs, in the worst meaning of the word. Here, in the brackets below, is the entire drawing that they need for first 300 pages of math and sketches:
[.]
They need only that much of detail to define the vehicle, select engines, determine weight limits, and so on. Once that dot "flies" in math, only then you might want to look at it closer.
If they work on robotics and such, a proper CAD is even more relevant because you can have parts made right after you designed the assembly, and you can put your robot together a week or two after that. No, this whole mess with "graphic artists" and F/OSS CAD is just a mess. Or at least the OP presented it as such. Maybe it's just a live demo of why only certain officers of a company, and not any random engineer who wants to, should talk to the press.
And you are suggesting to do stress and vibration analysis with that software? (none of the ones you list have any calculation quality beyond a fast and dirt check).
I don't suggest anything, I tell you what I use. There is a difference. What I use is suitable for my projects, and I don't design flight hardware. If you do, please make your own choices.
If you are curious, last time I used FloTherm for thermal/airflow simulations, Ansys Workbench for stress/deformation, and NASTRAN for vibration. Those are pure FEA packages that the company has licenses for. I use Cosmos tools and the little stress module in Inventor mainly for quick-and-dirty checks. There are many tools out there, and the designer should know what to use and when.
Yes, both things are something that I wanted to mention but it was too late.
It does make sense for a company to *add* something to the existing package if they think it is a good idea. Modern CADs allow easy addition of 3rd party applications to the system, so that they have access to the models and can do things. There is a good number of 3rd party add-ons for SolidWorks, for example. Your suggestion of refining "one thing" is very valid.
Outside of that, I do not know if Armadillo programmers' gaming experience fits well into the needs of a FEA. In games you need an approximate answer; an error within 10% would be invisible to the user. But you need the answer very fast. Gaming engine's physics module satisfies those requirements; you may need only integer math to get close enough. But in FEA modeling errors accumulate and propagate; they can lead to failure to converge when by all indications it should. So it is a matter of considerable concern, managing accuracy, precision and the size of the data (it's usually huge already.) SMP is typically supported by all modelers; some, like CST, support clusters. This is yet another thing that games don't need to worry about.
Also, NASA has lots of code specifically written for spacecraft simulation, and I'm sure Armadillo can get access to that - for use or for improvements as needed (and it is badly needed in some cases, the code is old.)
Your comment makes me wonder what Armadillo Aerospace could come up with (in software) for their own designs
This is not a new problem, really. What a startup didn't hear such a great idea from a young, enthusiastic engineer? "Boss, don't buy Quickbooks, don't waste $150, I will write the stuff for you for free!" If the boss doesn't know any better, such a proposition is usually a total loss. (Just have a look at QuickBooks for the proof.)
There are at least two issues at work here. First, do you have an expertise? And second, will your resources be better spent on something else, new perhaps, instead of reinventing the wheel?
As major CADs go, a mere $20K for a full SolidWorks seat is peanuts. Most of the labor that goes into the software is spent on interfaces; the rest is in licensed, very specialized libraries that do their job. For example, most 3D CADs use 3rd party math libraries that calculate all the solids and do all the heavy lifting. Simulation is very frequently done with 3rd party tools also, just because it's so hard to do fast. Ansys licenses their solvers to Autodesk, IIRC, as well as sells them independently (Ansys Workbench.) Then you go into the flow modeling (liquid, gas) and thermal modeling (in everything) - those represent yet another unique problem. The equations that describe the model are pretty well known; the real challenge is to simplify the model enough so that the computation ends before you die from old age, and at the same time retains enough accuracy. Meshers are a popular, very complex problem, most FEA tools have several adaptive meshes, and a lot of effort goes into building them.
All that takes an awful amount of time and resources. Armadillo probably doesn't have enough expertise to code most of the hard stuff. Sure they can do GUI, but that's the easy part. They'd need probably a few decades, given their limited workforce, to recreate the existing software, and that would cost them a lot, and they'd be making no progress on the rocket, and they'd be getting no grants for any of that. Unless they want to enter the market of simulation tools, they'd be better off working on their main goals, and paying pocket change for access to missing knowledge and skills (in form of simulation software, or consultants, or whatever.)
Why change what works?
Keyfobs allow you to use the car without ever removing them from the pocket or a bag.
Mechanical keys are dangerous too; apparently in some cars if you turn the key back one click too many the steering will lock. You probably don't want that at 65 mph.
The damned foot pedal brake is extremely uncommon here
When the parking brake is engaged there is a red indicator among instruments, it says BRAKE.
I'm sure your aunt would be just as much confused if she drove cars with an on/off button all her life, but this weird car has a key, like a house key, and you need to do something non-trivial with it!
Ok, let me explain. Either you buy an excellent 3D drafting / modeling software, or you spend 1,000x that much on paper analyses done by PhDs and on testing of real parts done at ranges and in test flights. The latter approach was used for Moon rockets - cost was no object. Those guys are welcome to borrow $100B and do the same; or they can borrow $100-200K and buy the best tools that are available today. But using play-do for things that life depends on is, IMO, beyond silly. I'd call it criminal, though as someone else already said they have no chance to even get to the point where they can kill someone with their rockets.
I do mechanical design and simulations, by the way, in SolidWorks/CosmosWorks, in Inventor, and with CoCreate/Nastran tools. Probably more. So I know a thing or two about this.
I looked briefly at the FreeCAD, it is impressive for a F/OSS project but I'm afraid it's not good enough yet to even make a plastic case for yer cell phone, let alone a propellant tank. For example:
The OP asked "what free s/w to use to build hardware to fly to the moon." My answer would be: "it doesn't matter, it won't work anyway." If I were to do the whole project, I would be first concerned about financing the whole project; cost of the best software on the market would be a drop in the ocean compared to everything else. People who started the moon project with a predetermined opinion what tools they will use won't get anywhere, not in the rocket science at least.
We have absolutely no evidence that FTL travel or communication is possible.
Absence of evidence != evidence of absence.
Our theories of Physics do not predict the possibility of FTL travel.
They don't predict many things. Our theories are incomplete, full of major assumptions, and still there are so many of them. The hope is that LHC will weed some out by proving them wrong. But we are not yet at the stage where we can definitively proclaim that FTL travel or messaging is impossible. Near-instant communication that we enjoy today would be a preposterous impossibility to a medieval king because no horse can run that fast.
Today we have theories that challenge some foundations. For example, this paper points out that if the speed of gravity were to be limited to 1c then our Solar system (just as all other) would spiral into the Sun pretty fast. It turns out, orbital mechanics calculations use infinite speed of gravity, and Pluto always "knows" exactly and instantly where the Sun is - not where it used to be hours ago. This is a very interesting paper.
Merely getting from there to here would consume so much energy
An ideal round trip in a potential field consumes zero energy. A pendulum can swing for a very long time, limited only by losses in the thread. Our rockets consume a lot of energy just because they are so incredibly inefficient.
About slow communications. I am indeed pessimistic about prospects of communicating if FTL messaging is proven to be impossible. There would be very little reason for dissimilar civilizations to spend vast resources on talking over light years and centuries of round trip time. If you want to ask "do you have antigravity?" it will require you a millennium to establish the dictionary, then ask the question and then to receive a response. Probably by that time you could figure it out yourself. And the answer would be probably already superceded by the newest research done at either end.
You do mention the continuous streaming of knowledge, and that might work, but it depends on willingness to spend considerable energy on an exchange that you will gain little out of (if you are an advanced civ.) Earth has nothing to say, except basics of our life.
Xenophobia is misplaced in this situation.
I only described concerns that would be valid if we encountered a version of our own civilization. To dismiss those concerns you need to show that our civilization is unusually violent and bloodthirsty. And I see nothing particularly unusual in how we developed so far. At every moment of our history our civilization was acting pretty logically for their time. There was no divine enlightenment, for example, no black monolith with 1x4x9 proportions - we arose from animals by just being more violent and more smart, and taking our time.
A cube farm usually has power, phone and Ethernet coming into each cube. Ethernet is usually routed from a switch somewhere in the back room. The link is very simple, and if it fails you just test the cable with a pocket tester or replace the switch.
Use of optical LAN may require *more* wiring, not less, depending on how many APs you need, and AP's cables have to climb walls if that's where your lasers are. You also need to feed power to them somehow, using PoE or from wall sockets. If something goes wrong you have several possible reasons, and the investigation will take longer, and it will be not as easy to replace a laser AP that is on the ceiling or high on the wall. Some faults can be caused by shadows, people passing by, and other problems that Ethernet is free of.
Leakage to other areas is not affected (unless you talk WiFi which isn't that popular in cube farms) because there are cables that go to laser APs anyway. The 1 Gbps speed is already provided over CAT6 Ethernet, and even if you push it to 10 Gbps somehow it won't make any difference because your SharePoint server still takes 10 seconds to display a page, and your Exchange server still takes minutes to "synchronize folders" because it is obviously such a monumental job.
Considering the cost of laser APs, and of their counterparts in each computer, and additional wiring, and additional complexity, a simple Ethernet cable laid by a lowly tech once, working forever and requiring no power, looks like a great deal.
I think it's safe to assume that point (1) is correct. We know very little about how interstellar travel will be conducted, but we do know that the energy cost of moving things between stars is extremely high.
The energy cost of a round trip is zero, unless your spaceship has friction against ether, or something. Besides, even if you use more wasteful ships, an advanced civilization is supposed to be able to afford their use if they make them in the first place.
As for point (2), Earth is nothing special.
You offer many guesses, but miss the one that several posters already mentioned. The aliens may want to simply destroy us as future competitors. They indeed don't need us or our planet or anything in between. They might just want us gone, like you want mice gone from your home. Just a guess, of course, but it has its place among others. And don't forget the hyperspace bypass theory too.
considering the cost of interstellar travel, any civilisation that makes a habit of sending ships to other worlds for the sole purpose of killing aliens isn't going to last very long.
You may be right, and when Earth starts shaking and falling apart under their destructor beams we should be sure that those aliens won't outlive us by much - a few million years, top.
I just love how everyone on Slashdot thinks that they know what some alien race is thinking, as if they themselves were from some alien race and have the key to their rationale.
One of those keys is indeed available to us; it's called "logic." Logic should be, to our best knowledge, universal across this Universe and it applies to all species equally. When we say that "civ. A may be worried that civ. B is hostile" this is just a statement of logic and has nothing to do with either civ. - unless the A is totally incapable of comprehending the word "hostile". And to that I find it unlikely that a civ. can sail all the way to the "advanced" stage without encountering opposition, be it from nature or from sentient things.
Logic is the foundation for math, and math is the foundation for science. A civilization can't become advanced without being well acquainted with logic. Therefore when faced with a problem of logic they will solve it just like we, or other civ. would do, given the inputs are the same or at least understood as variables.
You should put away your absolutes and your thoughts that 'humanity is superior', because we have no evidence to either.
Humanity, as matter of fact, is superior to animal kingdom. Historically, many groups of humans were superior to other groups. We know well how that works between humans. If we extrapolate this behavior onto other civilizations we always claim that it's a mere guess. But there is no law against guessing. Lacking more information, it is perfectly valid to presume (for some purposes) that aliens are just like us, because we have one sample of such species right here (and we have no samples of other, theorized species.)
We are so ignorant and arrogant that we expect other civilizations to think and act exactly like us [...] so they must be truculent and violent like we are
It is not unreasonable as a first guess. We are violent because it is our survival mechanism. Top predators have few offspring, they can't afford large losses. Rabbits multiply like rabbits, they depend on that instead of their teeth and claws.
The question is really when (or whether) the society transitions from violent survival mode to relaxed, peaceful mode. That's not easy to answer because our behavior is coded in our genes. Some civilizations, like Klingons, may even cherish this trait. We don't know how likely it is, but the one sample we have - ourselves - tells us that it's not an easy answer. And we can't even say that we are unique in our violent roots - there doesn't seem to be anything unnatural in what we do and how we ended up this way.
Most lights flash twice for each cycle.
However when connected to 3-phase power there are always two lights that are on for every one that is off.
Also when discussing street lights, it's practical to note that the lights shine down, not up. Only the light that is reflected by dark, gray asphalt, or grass, or trees (10% maybe?) escapes into space. An alien astronomer could write it off as lava flows from volcanos, given the spectrum of HPS lights.
what value would we get out of colonizing the moon. Or Venus or Mars? [...] We can't even bring ourselves to build reasonable colonies underwater on earth, or at the south pole
There are plenty of people who would be glad to leave their tyrannical states and go somewhere else, to create another state of their own, not as corrupt yet.
But there is no free place on Earth to do that. All usable land belongs to someone. Antarctica is so harsh and inhospitable that it probably rivals the Moon (get out without a suit and you die.) There is far more economic advantage to have a city on the Moon than in Antarctica.
Creating such a state under the sea is definitely a possibility, but it's quite expensive. Probably cheaper than doing the same on the Moon, but they both are orders of magnitude more costly than a bunch of wannabe settlers can collect. Eventually, though, underwater cities will be built - it makes plenty of sense; there are natural resources in oceans, and many people are used to living in steel (stone) caves already, so what's the difference? A city a mile underwater is also very safe from weather, and can be built to tolerate large earthquakes by making the buildings sufficiently light; if their supports fail they simply slowly drift some 100' to the bottom instead of crashing hard. Such a city is also safe from asteroids striking the planet.
technology is not going to allow us to circumvent the speed of light.
That can be said only if you have the Complete Theory of Everything in your posession. Besides, the 'c' limit is valid (if it is) in this Universe; we don't know that about other Universes. For example:
In the first 1E-35 seconds (that is 0.00..(34 zeroes)..01 seconds after the big bang the universe expanded to a diameter of something like 1 meter carrying all matter with it. So it was expanding something like 3E26 (that is 3 followed by 26 zeroes) times faster than the speed of light! (link)
That is because the space itself expanded faster than light. Find a way to create (and destroy) space at will and you have FTL. This, actually, had been proposed many decades ago by at least one SF writer.
Intergalactic travel is too energy-expensive to be a reasonable solution for any of the scenarios you outline.
I'm sure something like that was said to Columbus:
On 1 May 1486, permission having been granted, Columbus presented his plans to Queen Isabella, who, in turn, referred it to a committee. After the passing of much time, these savants of Spain, like their counterparts in Portugal, reported back that Columbus had judged the distance to Asia much too short. They pronounced the idea impractical, and advised their Royal Highnesses to pass on the proposed venture.
In 15th century a trip to Asia/Americas was too expensive for a king (and they were wrong about that too.) In 20th century a trip to Asia/Americas is cheap enough so that any working person can afford it. I wouldn't dare to opine about costs of future intergalactic trips.
Ships that would either whizz right by you, crash into you at relativistic speeds (with presumably fatal results), or have to spend most of their payload capacity decelerating before they got to you.
I see that you are not a Cosmic Engineer then. I would catch the incoming ship with some force field and recover all its kinetic energy while slowing it down. Remember, an advanced civilization, who builds a Dyson Sphere, is not necessarily limited to kerosene+LOX rockets.
25,000 light-years is still not going to be traversable in months.
Unless you are traveling near warp 10.
You presuppose that an advanced civilisation would not deliberately broadcast radio signals for others to detect?
I'd expect it to NOT broadcast. There is one simple reason - you never know who is going to receive those signals. Are you willing to bet the existence of your civilization on the theory that all civilizations are peaceful? We are the proof of the opposite.
a very advanced civilisation would realise that radio technology is cheap and simple
I'm sure they might do some deliberate broadcasting of their own towards likely stars, in the hope ob being detected.
Why would an advanced civilization "hope" that a young one developed tools to receive those signals? What is the benefit? The older civilization gains nothing, other than a new article in their Encyclopedia Galactica. The younger civilization, having no FTL, will probably go crazy. You can't maintain a dialog over the radio on the scale of the galaxy, the radio is too slow for that. Imagine that we received today a message from the stars, and the message says "Hi!" - what will happen to the world? And I'm very much unsure that the older civilization will be quick to send us the FTL formulas; likely it will require a lot of science before we can understand them, and without the common language it's hard to achieve. But the older civilization must also consider that we can receive and understand FTL, and then immediately make a weapon out of it. Knowing earthlings, it's a certainty.
As I mentioned earlier, the only sane way to use radio would be for the older civilization to monitor the stars (using probes or listening directly from their homeworld.) Once signals are received, an FTL ship with scientists should be sent to that star system to investigate and decide if the new one can be trusted with the contact.