For now. Still, getting back 27 engines for the loss of one is still a good tradeoff. It means wasting some fuel and limiting the maximum payload, tho.
Fuel is a small part of the cost of a launch. The maximum payload is only reduced if you want the cost saving of reusability. And one can reserve recycled boosters near the end of their useful life for higher payload missions.
Trolleybusses a) need a temporary shutdown of the roads until the wires are put up, c) need complicated wiring at crossings, and especially at central bus stops, level crossings with streetcars and electric trains and c) are not very flexible when it comes to rerouting compared with diesel busses.
Installing Trolleybus wiring isn't particularly disruptive. The wiring on our local trolleybus (MBTA 73) was removed a few years ago for a major road rebuild and later replaced without much fuss. Also battery operated busses have to be taken out of service periodically and parked somewhere for recharging and they have to carry very heavy battery packs, which increases their energy consumption. You are right, trolleybuses are less flexible, but that lack of flexibility can be an advantage in encouraging transit-oriented development.
The study is meaningless. Any advantage of Mercury being closer to Earth several time a year is completely overwhelmed by how deep Mercury is in the Sun's gravity well. In fact spacecraft that have gone to Mercury have had to perform one or more flybys of Venus to lower their potential energy. It takes a long time and much clever astrogation to get to Mercury with the rockets we have.
Clarke predicted stuff long before 1977. He was the first to suggest using artificial satellites in geostationary orbit as communication relays, way back in 1945.
They do need to know the local gravity to measure mass. There are absolute gravimeters that measure the local value of g by dropping an object in a vacuum chamber and measuring its acceleration to very high accuracy using a laser interferometer and an atomic clock. This does not depend on the mass of the test object by General Relatively. See the Wikipedia article on Gravimeter.
From the NASA Psyche web site:
"The Psyche mission will test a sophisticated new laser communication technology that encodes data in photons (rather than radio waves) to communicate between a probe in deep space and Earth."
Maybe some of the engineers laid off from the Dawn team could be employed as technical proof readers for NASA PR.
Nuclear power's higher costs may indeed make it uncompetitive with power from fossil fuel (and some of those higher cost are due to endless litigation by opposing environmentalists, at least in the U.S.). But if we have very little time to sharply cut CO2 emissions, ten years according to the IPCC, then we need to at least keep running the nuclear power plants we already have, even if the cost is higher. There is no way we can develop and bring on line enough renewable power to eliminate fossil fuel use in that time frame, and as long as we depend on some fossil fuel, shutting any nuclear plant results in a lot more CO2 emissions. Why aren't environmentalists demanding a moratorium on closing nuclear plants?
Amazon doesn't owe Wikipedia contributors anything. Contributions to Wikipedia are licensed under the Creative Commons Attribution-ShareAlike 3.0 licensed, under which "You are free: to Share—to copy, distribute and transmit the work, and to Remix—to adapt the work, for any purpose, even commercially." You still have to attribute the work and license your modifications under similar terms. (https://en.wikipedia.org/wiki/Wikipedia:Text_of_Creative_Commons_Attribution-ShareAlike_3.0_Unported_License)
Contributors agree to this license when they click "Publish changes." So maybe Amazon needs to do a better job of attribution, and million dollar gifts are always appreciated, but that about it.
Countries that are cutting back on nuclear power, particularly Germany and Japan, have largely escaped criticism. While both countries are making greater use of renewables, keeping nuclear plants running will eliminate CO2 emissions as long as they would otherwise burn some fossil fuels. If the situation is as grave as the report says, it's time for the green left, which has fought nuclear power relentlessly since the 1970s, to admit that maybe this was not such a good idea and push for nuclear in the mix.
Appleâ(TM)s emulations of the 68000 on the PowerPC and, later, the PowerPC on Intel worked quite well. They also had tools for distributing a program with separate binaries for different platforms. No doubt they can dust them off to distribute apps for both ARM and x86 when the time comes. Apple seems to be taking their time to think this through, which is wise.
A big factor was U.S. export controls. An operating system with strong security would require individual licenses to be sold in other countries. Remember 40-bit encryption keys?
When you call 911 or the equivalent, your phone should have the ability to respond using voice synthesis to queries from emergency services, sent using two or three digit touch-tone signals. The queries could include your GPS location and other information you supply, such as the floor you are usually on, apartment or office number, car make and model, chronic diseases, meds, allergies, and real time info, if available, from FitBits and the like. Maybe even a query for number and types of pets (that would be a big seller). Apple and Google could agree on a list of query codes and incorporate the feature in iOS and Android, with an opt-out for the paranoid. Since Touch-tone key pads are built into many phones and easily added if not, there would be no need for 911 call centers to update their technology, which can take decades, just have the code list handy. This is an easy fix.
In theory, frequently changed password make no sense. If someone guesses a complex password, it is either not complex, or obtained by asking the owner, or keylogged. None of these methods are prevented by frequent changes. And it encourages non complex, written down password.
The latest NIST guidelines, SP800-63B rev 3, specifically recommends against requiring regular password changes, except in cases of possible compromise. If a bad guy gets your password, they will use it soon, not wait three months.
On the other hand, advice against writing down passwords is also flawed, as long as the paper is kept someplace reasonably safe, like a locked drawer or your wallet. The main threat these days is remote attacks. If a sophisticated bad guy gains physical access to your property, they have many ways to compromise your password. And people are more likely to choose complex passwords if they can backup their memory with a written version. Password crackers can try tens of billions of passwords a second if they get hold of the types of password hashes commonly used, so a password complex enough to be safe (e.g. 6 random Diceware words) is too complex for most people to be confident they will remember it.
No, assembler wasn't available from the very beginning... but no one ever actually programmed in binary. They at least used decimal representations of instruction values and arguments. Even when systems (mostly hobby systems) had no input device other than toggle switches, you wrote out your code in decimal or hexadecimal, then translated to binary only for data entry. You would never "pore over" lines of binary except perhaps to check the translation from the more usable form right next to it.
Early computers had assembler programs and hardware input output. Early minicomputers were more primitive and one often had to enter a short bootstrap loader program into memory using front panel switches to get them started. The bootstrap program would remain in core memory until some program crash erased it.
Hexadecimal didn't become popular until the IBM 360 in the mid 1960's. Prior to that most computers were either decimal or binary with a sub multiple of 36 bits (36, 18, 12) and octal (base 8) was used to represent the contents of machine words. Switches and lights were grouped in threes and one quickly learned to set the switches from octal values and read the lights into octal. I never saw anyone writing programs in 1's and 0's.
[1]: One caveat is that some diceware dictionary contain words with less than 12.9 bits of entropy such as pairs of numbers (e.g. 21), in a case like that a naive brute force attack could actually outperform one that knows the dictionary in use.
That's not quite right. The entropy in Diceware, or any other system that selects random words from a list, comes for the number of words in the list, not from the individual words. It is of course possible that a random Diceware passphrase could consist entirely of "words" that were numeric, or single characters or the like, and that passphrase could then be vulnerable to a brute force attack, but the odds of that happening are extremely low and it would be easy to spot and just generate another passphrase. This is not much different from the fact that a password randomly selected from alphanumeric characters could (with very low probability) come out all numeric.
NASA-TV showed displays of the S-band and X-band carriers prior to loss of signal, sharp spikes above a noise background. The S-band signal faded out first, as the spacecraft began to lose pointing accuracy for its high gain antenna when the thrusters could no longer keep up with the atmospheric forces. The X-band signal persisted for a few more seconds (more antenna gain at the shorter wavelength, presumably) before it faded out, but then it reappeared briefly above the noise before going away forever. It was as if the spacecraft gave one last effort to stay in touch with home. A very sad moment.
I attended a presentation on the ARPAnet in the early 1970's and I asked about encryption. I was told they were not including encryption because doing so would mean the entire project would be classified and they very much wanted to avoid that (this was a few years before DES was released). They also said that DOD intended to encrypt each communication link (link encryption) in its network, which would also protect against traffic analysis.
Yes, if the $1200 model is the iPhone I like best, and I may buy more for family members too. I want a company that takes security seriously, that controls the entire product from the hardware up (no security if you don't) , that can update the software it provides without asking my cell carrier for permission, that is willing to stand up to the FBI, and, yes, that vets every app I download. I consider the last a valuable service; you may not. $1200 over two or maybe three years is dirt cheap compared to what I am getting.
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For now. Still, getting back 27 engines for the loss of one is still a good tradeoff. It means wasting some fuel and limiting the maximum payload, tho.
Fuel is a small part of the cost of a launch. The maximum payload is only reduced if you want the cost saving of reusability. And one can reserve recycled boosters near the end of their useful life for higher payload missions.
Trolleybusses a) need a temporary shutdown of the roads until the wires are put up, c) need complicated wiring at crossings, and especially at central bus stops, level crossings with streetcars and electric trains and c) are not very flexible when it comes to rerouting compared with diesel busses.
Installing Trolleybus wiring isn't particularly disruptive. The wiring on our local trolleybus (MBTA 73) was removed a few years ago for a major road rebuild and later replaced without much fuss. Also battery operated busses have to be taken out of service periodically and parked somewhere for recharging and they have to carry very heavy battery packs, which increases their energy consumption. You are right, trolleybuses are less flexible, but that lack of flexibility can be an advantage in encouraging transit-oriented development.
The study is meaningless. Any advantage of Mercury being closer to Earth several time a year is completely overwhelmed by how deep Mercury is in the Sun's gravity well. In fact spacecraft that have gone to Mercury have had to perform one or more flybys of Venus to lower their potential energy. It takes a long time and much clever astrogation to get to Mercury with the rockets we have.
Clarke predicted stuff long before 1977. He was the first to suggest using artificial satellites in geostationary orbit as communication relays, way back in 1945.
They do need to know the local gravity to measure mass. There are absolute gravimeters that measure the local value of g by dropping an object in a vacuum chamber and measuring its acceleration to very high accuracy using a laser interferometer and an atomic clock. This does not depend on the mass of the test object by General Relatively. See the Wikipedia article on Gravimeter.
From the NASA Psyche web site: "The Psyche mission will test a sophisticated new laser communication technology that encodes data in photons (rather than radio waves) to communicate between a probe in deep space and Earth." Maybe some of the engineers laid off from the Dawn team could be employed as technical proof readers for NASA PR.
Nuclear power's higher costs may indeed make it uncompetitive with power from fossil fuel (and some of those higher cost are due to endless litigation by opposing environmentalists, at least in the U.S.). But if we have very little time to sharply cut CO2 emissions, ten years according to the IPCC, then we need to at least keep running the nuclear power plants we already have, even if the cost is higher. There is no way we can develop and bring on line enough renewable power to eliminate fossil fuel use in that time frame, and as long as we depend on some fossil fuel, shutting any nuclear plant results in a lot more CO2 emissions. Why aren't environmentalists demanding a moratorium on closing nuclear plants?
Amazon doesn't owe Wikipedia contributors anything. Contributions to Wikipedia are licensed under the Creative Commons Attribution-ShareAlike 3.0 licensed, under which "You are free: to Share—to copy, distribute and transmit the work, and to Remix—to adapt the work, for any purpose, even commercially." You still have to attribute the work and license your modifications under similar terms. (https://en.wikipedia.org/wiki/Wikipedia:Text_of_Creative_Commons_Attribution-ShareAlike_3.0_Unported_License) Contributors agree to this license when they click "Publish changes." So maybe Amazon needs to do a better job of attribution, and million dollar gifts are always appreciated, but that about it.
OP should have mentioned a security tax too.
Countries that are cutting back on nuclear power, particularly Germany and Japan, have largely escaped criticism. While both countries are making greater use of renewables, keeping nuclear plants running will eliminate CO2 emissions as long as they would otherwise burn some fossil fuels. If the situation is as grave as the report says, it's time for the green left, which has fought nuclear power relentlessly since the 1970s, to admit that maybe this was not such a good idea and push for nuclear in the mix.
If they start including their new AI processors in the laptops and desktops along with their A-series processors, that could be interesting.
Appleâ(TM)s emulations of the 68000 on the PowerPC and, later, the PowerPC on Intel worked quite well. They also had tools for distributing a program with separate binaries for different platforms. No doubt they can dust them off to distribute apps for both ARM and x86 when the time comes. Apple seems to be taking their time to think this through, which is wise.
Which fonts work best for you?
A big factor was U.S. export controls. An operating system with strong security would require individual licenses to be sold in other countries. Remember 40-bit encryption keys?
When you call 911 or the equivalent, your phone should have the ability to respond using voice synthesis to queries from emergency services, sent using two or three digit touch-tone signals. The queries could include your GPS location and other information you supply, such as the floor you are usually on, apartment or office number, car make and model, chronic diseases, meds, allergies, and real time info, if available, from FitBits and the like. Maybe even a query for number and types of pets (that would be a big seller). Apple and Google could agree on a list of query codes and incorporate the feature in iOS and Android, with an opt-out for the paranoid. Since Touch-tone key pads are built into many phones and easily added if not, there would be no need for 911 call centers to update their technology, which can take decades, just have the code list handy. This is an easy fix.
Could be a good location for wind power.
Much of Manhattan in New York City has long been heated by waste heat steam from the power company (ConEd).
In theory, frequently changed password make no sense. If someone guesses a complex password, it is either not complex, or obtained by asking the owner, or keylogged. None of these methods are prevented by frequent changes. And it encourages non complex, written down password.
The latest NIST guidelines, SP800-63B rev 3, specifically recommends against requiring regular password changes, except in cases of possible compromise. If a bad guy gets your password, they will use it soon, not wait three months. On the other hand, advice against writing down passwords is also flawed, as long as the paper is kept someplace reasonably safe, like a locked drawer or your wallet. The main threat these days is remote attacks. If a sophisticated bad guy gains physical access to your property, they have many ways to compromise your password. And people are more likely to choose complex passwords if they can backup their memory with a written version. Password crackers can try tens of billions of passwords a second if they get hold of the types of password hashes commonly used, so a password complex enough to be safe (e.g. 6 random Diceware words) is too complex for most people to be confident they will remember it.
No, assembler wasn't available from the very beginning... but no one ever actually programmed in binary. They at least used decimal representations of instruction values and arguments. Even when systems (mostly hobby systems) had no input device other than toggle switches, you wrote out your code in decimal or hexadecimal, then translated to binary only for data entry. You would never "pore over" lines of binary except perhaps to check the translation from the more usable form right next to it.
Early computers had assembler programs and hardware input output. Early minicomputers were more primitive and one often had to enter a short bootstrap loader program into memory using front panel switches to get them started. The bootstrap program would remain in core memory until some program crash erased it. Hexadecimal didn't become popular until the IBM 360 in the mid 1960's. Prior to that most computers were either decimal or binary with a sub multiple of 36 bits (36, 18, 12) and octal (base 8) was used to represent the contents of machine words. Switches and lights were grouped in threes and one quickly learned to set the switches from octal values and read the lights into octal. I never saw anyone writing programs in 1's and 0's.
[1]: One caveat is that some diceware dictionary contain words with less than 12.9 bits of entropy such as pairs of numbers (e.g. 21), in a case like that a naive brute force attack could actually outperform one that knows the dictionary in use.
That's not quite right. The entropy in Diceware, or any other system that selects random words from a list, comes for the number of words in the list, not from the individual words. It is of course possible that a random Diceware passphrase could consist entirely of "words" that were numeric, or single characters or the like, and that passphrase could then be vulnerable to a brute force attack, but the odds of that happening are extremely low and it would be easy to spot and just generate another passphrase. This is not much different from the fact that a password randomly selected from alphanumeric characters could (with very low probability) come out all numeric.
Thanks for the correction.
NASA-TV showed displays of the S-band and X-band carriers prior to loss of signal, sharp spikes above a noise background. The S-band signal faded out first, as the spacecraft began to lose pointing accuracy for its high gain antenna when the thrusters could no longer keep up with the atmospheric forces. The X-band signal persisted for a few more seconds (more antenna gain at the shorter wavelength, presumably) before it faded out, but then it reappeared briefly above the noise before going away forever. It was as if the spacecraft gave one last effort to stay in touch with home. A very sad moment.
I attended a presentation on the ARPAnet in the early 1970's and I asked about encryption. I was told they were not including encryption because doing so would mean the entire project would be classified and they very much wanted to avoid that (this was a few years before DES was released). They also said that DOD intended to encrypt each communication link (link encryption) in its network, which would also protect against traffic analysis.
Yes, if the $1200 model is the iPhone I like best, and I may buy more for family members too. I want a company that takes security seriously, that controls the entire product from the hardware up (no security if you don't) , that can update the software it provides without asking my cell carrier for permission, that is willing to stand up to the FBI, and, yes, that vets every app I download. I consider the last a valuable service; you may not. $1200 over two or maybe three years is dirt cheap compared to what I am getting.
From ruling: "GORSUCH, J., took no part in the consideration or decision of the case."