Some problems that occur to me with trying to broadcast messages. The number one problem of course is that all of our broadcasts (and the signals we are trying to receive with SETI) are travelling at the speed of light. That means that for all but nearby star systems, the messages will not arrive until the senders are long dead. For even the very closest couple of star systems, we are talking 5 or 6 years to receive a response to a message we send. And while it is not certain, there is a reasonably good chance that if any "civilization" existed on a nearby star system, we would have detected them by now.
The problem with targetting star systems is figuring out which ones to target. So far we have not found one single system outside our own with "planets in a temperate climate that can harbor life", simply because we do not yet have the technology capable of finding such a thing. The best we can do currently is select systems with a single sun like star, but that number is probably still in the billions in our galaxy.
And finally, there is the problem of the alien civilization detecting our signals. Unless our laser is putting out a beam that will exceed the brightness of the sun, the other system will have to have an ongoing program to search for lasers, that has continued uninterrupted for millions of years (since it is unlikely they will be at the same stage of evolution as us). That system would have to be comprehensive, scanning the entire sky, if they don't already know where we are. And if they do already know where we are, then it is pretty clear they do not want to talk to us yet.
Face it, technology always kills people. Here is another angle: These people where definitely killed by airplanes. Banning airplanes would have saved these people.
What is the answer? Ban airplanes?
Not good enough. A truck loaded with exposives was used in Oklahoma City. So ban trucks. A powerboat was used in Yemen. So ban powerboats. Explosives have been sent as mailbombs. So ban mail.
What I would really like is some context to this quote. Does anyone know of a link to a web page with something more than just this quote and no context?
Oh, Andreas can be just as rude to long time developers, too. But I do think he is an excellent example of the kind of person needed to make an OS project work. He is almost dictatorial about where the code is headed, but is completely open to patches from anyone as long as they do not stray from that path and are good code.
"Open Source" definitely is not a magic incantation that confers success and greatness on any software. Linux would never have made it to where it is today without Linus. And I think similarly Wine would not be where it is without Andreas.
Having stood directly under several different wind turbines (we have lots of them here in California), I can assure you that not only is the "whoosh" there, it is quite loud. I cannot imagine how they will prevent that sound being transmitted through the building. And while each whoosh is white noise in nature, the rythmic pulsing of it is not.
Nyquist only applies to digitizing an analog signal, and has nothing to do with compression. Compression can easily far exceed the Nyquist limit, but the claims of this particular article are hard to believe. I would not not invest any money until I see the box with the lid off!
I have thought that a really cool thing to do would be to put a mirror manufacturing facility in space. Launching a large mirror, or mirrors, is difficult. But launching raw materials would be much easier; and it could use unmanned rockets, for example. Then you could make truely huge mirrors, and make them (relatively) thin with none of the support structure needed for launch.
Even more random speculation. The mirror facility could me near to but not neccesarily connected to the space station. It would be mostly automated, but someone from the space station could hop over on occasion for checkups and tweaks. Oh well, enough idle dreaming for now.
JPL does say that their images are indeed reversed. "The stereo-pair images are reversed; that is to say, the "left-eye" image is on the right side of the pair. This is intentional. It is set up for cross-eyed viewing, as indicated on the image."
There is a trick that I use to do (almost) naked eye viewing of images that are like this (and I actually find it easier on my eyes). By the way, what are the links to some of the images you were looking at?
Close your left eye and slide your right hand in from the right, about a foot in front of your face, until it blocks the right image but not the left image. So now your right eye is looking at the left image. Now, while trying to keep that hand approximately where it was, close the right eye and open the left, and similarly slide your left hand in from the left.
Now you can open both eyes, and do a little fine tuning with your hands, maybe moving them slightly forward or back to get the image visibility right. It sounds kind of complicated, but in practice, I found it pretty easy to do.
Notice that is an average vertical accuracy of 13 meters. But the horizontal accuracy is one one point every 60 kilometers. You are not going to get a very detailed map out of that!
However, the Magellan spacecraft had made somewhat detailed radar images of Venus long before SRTM flew, though not topographic maps, and not to nearly the resolution and accuracy of SRTM.
Umm... I designed and built some of the hardware for SIR-C (and also SRTM). There was absolutely no military connection to SIR-C. And X-SAR was built by the European space agencies, primarily the Italians on the antenna, and the Germans on the digital hardware, and they also had no military connection. The US military only got involved in SRTM after they saw how well the SIR-C radar worked, and after some of the SIR-C folks went looking for money to upgrade SIR-C to SRTM.
SIR-C did not make topographic maps, except for one or two special tests using a technique called "repeat pass interferometry", because it did not have the outboard antenna on the 60M mast that SRTM had, and which gave SRTM its "stereo vision". And SIR-C only imaged a few small strips of the earth, each specifically requested by a scientist for some research purpose, or of course a few strips taken for PR purposes. SIR-C did not attempt to make a global map. This data is in the hands of the scientists involved, who supposedly continue to turn out papers based on the data. Also, SIR-C was conceived as a technology test experiment (and is also referred to as SRL - Space Radar Laboratory), used to test a variety of new radar technologies to see how well they worked from a spacebased platform.
Terraserver, and other systems that produce resolutions on the order of 1 meter, are photographic systems. SRTM is an imaging radar system, with resolution of 20-30 meters. And the key part of the phrase in your quote is "better than any global map".
The primary job of SRTM was to generate a uniform global topographic map. There are other radar systems, such as geosar, which can get better resolution. But that is because they are mounted on airplanes, and are therefore flying much closer to their target. But you are unlikely see a global map from geosar, or any other airborne radar, because, well, the earth is just too big to cover it all in an airplane. And just trying flying a US military imaging radar on an airplane over China! They get grumpy enough about the spy planes flying off their coast. And yet SRTM made a world wide map in a single 10 day mission (except somehow they missed Area 51 - don't know how that happened).
And the value of a uniform map is that there are maps around from literally hundreds of data sources, but maps of two different areas, made with two different data sets, are difficult to compare accurately without a uniform baseline to compare them against. SRTM data is intended to be that baseline.
And finally, an advantages of radar data over photographic data is that it is difficult to get accurate topographic data from optical data. Also, you are at the mercy of the weather when obtaining photo data. The radar can see through clouds just fine.
No need to sound paranoid. In fact, major funding for this mission was provided by NIMA, primarily for the purpose of generating maps for cruise missiles. However, JPL (who ran the mission) managed to get the condition that somewhat lower resolution data would be released to researchers. Actually, I believe US data will be released at full resolution, because high resolution is already available anyway.
Leeward - In mission control, Houston, for the SRTM mission (but not now a NASA employee).
This idea that a citizen of one country, engaged in acts within that country which are legal in that country, can be arrested in another country for those acts, is truely scary. Though it does seem to be the latest trend.
I guess this means that anyone employed by Adobe had better not visit Russia. They run the risk of being arrested for working for a company that produces software which is, apparently, illegal in Russia. Anyone considering a visit to a foriegn country will soon need to consult a lawyer to determine whether it is safe to do so.
I am real surprised no one has posted a Linux friendly URL yet. In any case, I don't know how it compares to those Windoze Media files, but space.com has a nice little video, complete with dramatic music in stereo. And it is available in RealPlayer, as well as Quicktime and the ubiquitous Windoze Media.
I'm just wondering what the heck are these floppies that everyone is talking about. Does anyone have some links or something so I can find out more about them? Just out of historical curiosity of course.
What you say is true if you are building "the fastest microprocessors in the known universe". But FPGAs are rapidly getting extremely powerful, and their cost keeps dropping. A great deal of power, and the tools to develop code for them, is right now readily available at a price that is affordable to even your average college engineering student. And I think this is a good thing.
Multi million gate, very fast FPGAs are already available, and I personally don't think it will be very many years before they are suitable for general purpose microprocessors, rather than just special purpose reconfigurable computers. And when that happens then:
Anybody can fix it when it breaks. I have seen in the last couple of years a dramatic increase in the number of VHDL simulators available, and a corresponding decrease in the cost of them. When someone identifies the problem, they will just write a patch, and then you will download into your FPGA/microprocessor/whatever hardware. This idea is already available with Xilinx Internet Reconfigurable Logic.
You can tweak it to your needs. Just as with software, your typical hacker is not going to do extensive verification. They will do a quick simulation to test the changes they made, load the design into the FPGA, and try it out. And if it doesn't work right, just do another iteration.
How many people are going to learn Verilog/VHDL? How many people have learned JAVA, Python, Perl... (this list is almost endless). And my HP16500 mostly sets in a corner gathering dust. I am now seeing the practice of imbedding a logic analyzer into the FPGA, and having a GUI frontend on your computer.
Slashdot Mirror
And not only that, but there is (yet another) unadvertised pref. Adding:
, true);
user_pref("browser.tabs.opentabfor.middleclick"
to prefs.js, or better, user.js, allows you to open a new tab by clicking the middle button on a link.
Some problems that occur to me with trying to broadcast messages. The number one problem of course is that all of our broadcasts (and the signals we are trying to receive with SETI) are travelling at the speed of light. That means that for all but nearby star systems, the messages will not arrive until the senders are long dead. For even the very closest couple of star systems, we are talking 5 or 6 years to receive a response to a message we send. And while it is not certain, there is a reasonably good chance that if any "civilization" existed on a nearby star system, we would have detected them by now.
The problem with targetting star systems is figuring out which ones to target. So far we have not found one single system outside our own with "planets in a temperate climate that can harbor life", simply because we do not yet have the technology capable of finding such a thing. The best we can do currently is select systems with a single sun like star, but that number is probably still in the billions in our galaxy.
And finally, there is the problem of the alien civilization detecting our signals. Unless our laser is putting out a beam that will exceed the brightness of the sun, the other system will have to have an ongoing program to search for lasers, that has continued uninterrupted for millions of years (since it is unlikely they will be at the same stage of evolution as us). That system would have to be comprehensive, scanning the entire sky, if they don't already know where we are. And if they do already know where we are, then it is pretty clear they do not want to talk to us yet.
Face it, technology always kills people. Here is another angle: These people where definitely killed by airplanes. Banning airplanes would have saved these people.
What is the answer? Ban airplanes?
Not good enough. A truck loaded with exposives was used in Oklahoma City. So ban trucks. A powerboat was used in Yemen. So ban powerboats. Explosives have been sent as mailbombs. So ban mail.
And the list goes on...
What I would really like is some context to this quote. Does anyone know of a link to a web page with something more than just this quote and no context?
Oh, Andreas can be just as rude to long time developers, too. But I do think he is an excellent example of the kind of person needed to make an OS project work. He is almost dictatorial about where the code is headed, but is completely open to patches from anyone as long as they do not stray from that path and are good code.
"Open Source" definitely is not a magic incantation that confers success and greatness on any software. Linux would never have made it to where it is today without Linus. And I think similarly Wine would not be where it is without Andreas.
Having stood directly under several different wind turbines (we have lots of them here in California), I can assure you that not only is the "whoosh" there, it is quite loud. I cannot imagine how they will prevent that sound being transmitted through the building. And while each whoosh is white noise in nature, the rythmic pulsing of it is not.
Nyquist only applies to digitizing an analog signal, and has nothing to do with compression. Compression can easily far exceed the Nyquist limit, but the claims of this particular article are hard to believe. I would not not invest any money until I see the box with the lid off!
I have thought that a really cool thing to do would be to put a mirror manufacturing facility in space. Launching a large mirror, or mirrors, is difficult. But launching raw materials would be much easier; and it could use unmanned rockets, for example. Then you could make truely huge mirrors, and make them (relatively) thin with none of the support structure needed for launch.
Even more random speculation. The mirror facility could me near to but not neccesarily connected to the space station. It would be mostly automated, but someone from the space station could hop over on occasion for checkups and tweaks. Oh well, enough idle dreaming for now.
JPL does say that their images are indeed reversed. "The stereo-pair images are reversed; that is to say, the "left-eye" image is on the right side of the pair. This is intentional. It is set up for cross-eyed viewing, as indicated on the image."
There is a trick that I use to do (almost) naked eye viewing of images that are like this (and I actually find it easier on my eyes). By the way, what are the links to some of the images you were looking at?
Close your left eye and slide your right hand in from the right, about a foot in front of your face, until it blocks the right image but not the left image. So now your right eye is looking at the left image. Now, while trying to keep that hand approximately where it was, close the right eye and open the left, and similarly slide your left hand in from the left.
Now you can open both eyes, and do a little fine tuning with your hands, maybe moving them slightly forward or back to get the image visibility right. It sounds kind of complicated, but in practice, I found it pretty easy to do.
Notice that is an average vertical accuracy of 13 meters. But the horizontal accuracy is one one point every 60 kilometers. You are not going to get a very detailed map out of that!
However, the Magellan spacecraft had made somewhat detailed radar images of Venus long before SRTM flew, though not topographic maps, and not to nearly the resolution and accuracy of SRTM.
Umm... I designed and built some of the hardware for SIR-C (and also SRTM). There was absolutely no military connection to SIR-C. And X-SAR was built by the European space agencies, primarily the Italians on the antenna, and the Germans on the digital hardware, and they also had no military connection. The US military only got involved in SRTM after they saw how well the SIR-C radar worked, and after some of the SIR-C folks went looking for money to upgrade SIR-C to SRTM.
SIR-C did not make topographic maps, except for one or two special tests using a technique called "repeat pass interferometry", because it did not have the outboard antenna on the 60M mast that SRTM had, and which gave SRTM its "stereo vision". And SIR-C only imaged a few small strips of the earth, each specifically requested by a scientist for some research purpose, or of course a few strips taken for PR purposes. SIR-C did not attempt to make a global map. This data is in the hands of the scientists involved, who supposedly continue to turn out papers based on the data. Also, SIR-C was conceived as a technology test experiment (and is also referred to as SRL - Space Radar Laboratory), used to test a variety of new radar technologies to see how well they worked from a spacebased platform.
Terraserver, and other systems that produce resolutions on the order of 1 meter, are photographic systems. SRTM is an imaging radar system, with resolution of 20-30 meters. And the key part of the phrase in your quote is "better than any global map".
The primary job of SRTM was to generate a uniform global topographic map. There are other radar systems, such as geosar, which can get better resolution. But that is because they are mounted on airplanes, and are therefore flying much closer to their target. But you are unlikely see a global map from geosar, or any other airborne radar, because, well, the earth is just too big to cover it all in an airplane. And just trying flying a US military imaging radar on an airplane over China! They get grumpy enough about the spy planes flying off their coast. And yet SRTM made a world wide map in a single 10 day mission (except somehow they missed Area 51 - don't know how that happened).
And the value of a uniform map is that there are maps around from literally hundreds of data sources, but maps of two different areas, made with two different data sets, are difficult to compare accurately without a uniform baseline to compare them against. SRTM data is intended to be that baseline.
And finally, an advantages of radar data over photographic data is that it is difficult to get accurate topographic data from optical data. Also, you are at the mercy of the weather when obtaining photo data. The radar can see through clouds just fine.
No need to sound paranoid. In fact, major funding for this mission was provided by NIMA, primarily for the purpose of generating maps for cruise missiles. However, JPL (who ran the mission) managed to get the condition that somewhat lower resolution data would be released to researchers. Actually, I believe US data will be released at full resolution, because high resolution is already available anyway.
Leeward - In mission control, Houston, for the SRTM mission (but not now a NASA employee).
This idea that a citizen of one country, engaged in acts within that country which are legal in that country, can be arrested in another country for those acts, is truely scary. Though it does seem to be the latest trend.
I guess this means that anyone employed by Adobe had better not visit Russia. They run the risk of being arrested for working for a company that produces software which is, apparently, illegal in Russia. Anyone considering a visit to a foriegn country will soon need to consult a lawyer to determine whether it is safe to do so.
Click on Reentry Video.
I'm just wondering what the heck are these floppies that everyone is talking about. Does anyone have some links or something so I can find out more about them? Just out of historical curiosity of course.
See Internet Reconfigurable Logic from Xilinx. These chips are now in the multi million gate range.
Multi million gate, very fast FPGAs are already available, and I personally don't think it will be very many years before they are suitable for general purpose microprocessors, rather than just special purpose reconfigurable computers. And when that happens then:
Anybody can fix it when it breaks. I have seen in the last couple of years a dramatic increase in the number of VHDL simulators available, and a corresponding decrease in the cost of them. When someone identifies the problem, they will just write a patch, and then you will download into your FPGA/microprocessor/whatever hardware. This idea is already available with Xilinx Internet Reconfigurable Logic.
You can tweak it to your needs. Just as with software, your typical hacker is not going to do extensive verification. They will do a quick simulation to test the changes they made, load the design into the FPGA, and try it out. And if it doesn't work right, just do another iteration.
How many people are going to learn Verilog/VHDL? How many people have learned JAVA, Python, Perl... (this list is almost endless). And my HP16500 mostly sets in a corner gathering dust. I am now seeing the practice of imbedding a logic analyzer into the FPGA, and having a GUI frontend on your computer.