The Burst And Transient Source Experiment (BATSE) on board the Compton Gamma-Ray Observatory made many observations of TGFs from low-Earth orbit between 1991 and 2000. In fact, our second event after turning on the instrument was located to the Earth; very surprising, in view of the fact that we didn't expect *any*! The ironic part is that our main objects of study, gamma-ray bursts, were discovered by a series of satellites (Vela) that were monitoring the Earth (and the far side of the Moon) for gamma-rays indicating violations of the nuclear test ban treaty with the (then) Soviet Union. Seeing nothing from the Earth, the Los Alamos scientists looked for any other signal...
Terrestrial Gamma Flashes have been detected by orbiting instruments for some time; at least since 1991,iirc. What's new here is the definite signature of positron annihilation; this can only be done with a sufficiently large detector looking at the right energy. The Burst Monitor on Fermi was designed to catch the medium energies of gamma-ray bursts (as well as low- and high energies), so this was a nice add-on to the main science.
You can always tell when a story is based on a NASA press release. If the spacecraft exceeded its mission expectations, it's a "NASA spacecraft." But if it failed, it's a "Lockheed-built spacecraft" (or whichever contractor they decide to blame).
For a change it would be nice to see NASA give kudos to whatever contractor built the successful spacecraft for them. Umm. some of NASA's spacecraft are delivered to the agency in-orbit, after checkout. Until then, they remain the property of the contractor. This is the case with GLAST, which was just launched, but will remain with General Dynamics until L+60 days.
Homeland Security Presidential Directive 12 has far-reaching implications. I am a state university research professor and receive funding from a NASA project. Even though I am a Co-Investigator on this project, I was told by my own management and University counsel that I would not be allowed access to my own data, should I refuse to sign, and thus cut myself off from my own funding. Fired, in other words. Needless to say, I signed.
As far as I can determine, HSPD-12 applies to *all* Gov't. agencies that supply computer network support. Now, imagine trying to get a foreign national on such networks for international collaboration...
Your tax dollars (US citizens only!) are now being spent investigating me and all my colleagues, so that we can continue to have the NASA computer accounts we've already held for years.
Although Einstein wanted to show that Mach's Principle applied to the universe (which is what the Parent Poster was implying), he couldn't make it work in the framework of General Relativity. Essentially, we only feel the net force of matter within our horizon (defined loosely as the portion of the Universe visible to us since the beginning of time) and move accordingly. A portion of the Universe with net angular momentum that is non-zero is not ruled out in GR, spiral galaxies are an example on one length scale; this new result carries this to a much larger scale!
Why 1/10th c? Why not 99% of c? Why not faster than c? Granted faster than light travel is nothing more than theory and dreams at this point, but this article makes the assumption that other civilizations have not progressed in the field of physics any faster nor further than we ourselves have, to date.
You are excused for not knowing the fantastic amount of energy (in the form of consumables) required to even approach the 10% figure. Something like (off the top of my head, now) 10 times the weight of the entire probe will be needed to accelerate it to these speeds and then decelerate it at the far end. For every ten percentile closer to c you want to attain, you will need (roughly) ten times more propellant; a very real Zeno's paradox! This is pure physics; no Sci-Fi techniques need apply; since, if you assume magic, well, then anything's possible. In fact, the Fermi paradox tells us as much about the limitations of physics as anything else...
Why, yes, I *am* a rocket scientist (actually, an astrophysicist).
Sneaking in under the radar has been the iTunes Store from Apple. It is a desktop app; no, it is a web-based app. Actually, it is both, and a very successful model for the future.
... three members of NASA's advisory panel resigned for telling Griffen what he didn't want to know: that NASA is stealing money from science. Two of these were asked outright to leave and the other quit in sympathy (check NASA watch). To paraphrase: NASA doesn't need anyone to comment on current policy. Yet another example of how far Griffen has fallen to support the Bush adminitration's 'NASA as feeder for the aerospace business' policy. Sure, we'll get cargo to space, but it will consist of McDonalds (tm) hambugers for the ISS. Sorry I'm so bitter about this, but there goes your tax dollars (US readers!). Think of what $500 million US could do for the shrinking portion devote to the NASA science budget; which, by the way, has helped to fund the current and next generations of astronomy and astrophysics researchers in the US. Given the nature of the research, that helped everyone by advancing fundamental science research.
If we are truly able to upload or create or model intelligences in AI, they will be subject to *exactly* the same kind of boredom that we would experience. Otherwise, they would not be fair copies! Even worse, these intelligences would have no bodies for eating, drinking, or doing any of the tasks *we* might do to relieve the tedium. At best, you could turn them off until they reach their destination and hope that the `On' switch survives the trip! GRR
Wait, aren't we talking at the speed at which we "travel" into time? I think the meaning of dt/dt is to say that time can only appear to go at always the same rate
This is where the original article has lead everyone astray: in GR (General Relativity), only the dx, dy, dz, and dt have meaning, not any of their ratios. In fact, in the broadest interpretation of GR, there is no special place for dt, it is just one of four mixed coordinates. Velocities are all (wait for it!)... relative. I've been reading a lot about this lately, which is why the simplistic tone of the article really grates on me.
You describe spacial travel as the dx, not the dx/dt. It stands to reason that you would describe time travel with the dt, not as some rate of travel we haven't come up with yet.
I *am* a physicist, and this guy just holed the article in one line. Good one!
OK. I am also an astrophysicist, and I have been studying gravity in its string theory and loop quantum guises. Gravitational waves carry information, so they will *not* come out of a black hole horizon. However, gravity (as expressed in the theory of General Relativity) obeys what is called Gauss's law, which just means to say that it doesn't matter (!) what lies beneath the spherical BH horizon, or *any* imaginary sphere that surrounds it, gravity only depends upon the total mass (or equivalent energy) contained within. No gravitons need escape the BH horizon to create the gravity equivalent to the mass gobbled up by the hole. - GRR
Make sure there's an atmosphere! We have survived being right next to an inconstant star for quite some time. Some of those recent X-class solar flares have been quite fierce.
As soon as it gets to the point where it becomes a re-entry risk (which happens when only one gyro remains functional), NASA will drop it into the Pacific. They don't want to risk an unplanned, uncontrolled descent that may put it in the middle of a population area.
Except, of course, it currently has no de-orbit capability, hence the plan to go there and add it. But, if you already have to go there...
But that's the wrong way to go. Microsoft, Apple, and other vendors need to figure out how to create software platforms that allow good integration between applications that weren't developed by a single team. And none of them have managed that yet.
True integration requires open, flexible standards for content and inter-application communications. Nobody has really figured out how to do that yet, least of all Microsoft and Apple.
This is a good point. Apple developed something called OpenDoc, which consisted of object-oriented documents with plug-in replaceable reader and content generator code. That way, if you didn't like the text editor, you simply bought another that worked the way you wished. BBEdit had a module that replaced the one Apple shipped. IIRC, ODoc was killed in a MS-Apple deal that left Office running on Macs...
The Dublin conference talk isn't old news, but the possibility that Hawking was wrong has been growing for some time. General Relativity is, after all, a classical theory, which means that it must be invalid at high gravitational field strengths, such as you might find at the center of any black hole. It was shown some time ago by Polchinski (sp?) that certain aspects of string theory allow for enough freedom to solve the informational problem and, at the same time, account for the black hole entropy theorem. Thus, it was said that the center of each black hole harbors a 'stringularity'.
If we don't get a good fuel before the price of oil jacks up, then the only viable form of transportation is going to be electric rail, which is fine for dense areas, but is bad news for the US.
You're wrong. Aether was thought to be a physical fluid whose ripples were the basis of the wave-like nature of light. This was proven not to be so by Michelson and Morely, who showed that the speed of light was the same no matter if it were going with or against the aether (which was presumably flowing past the moving Earth). Dark energy is a field, like light or gravity, which presumably has no preferred frame of reference (like light or gravity).
Slashdot Mirror
The Burst And Transient Source Experiment (BATSE) on board the Compton Gamma-Ray Observatory made many observations of TGFs from low-Earth orbit between 1991 and 2000. In fact, our second event after turning on the instrument was located to the Earth; very surprising, in view of the fact that we didn't expect *any*! The ironic part is that our main objects of study, gamma-ray bursts, were discovered by a series of satellites (Vela) that were monitoring the Earth (and the far side of the Moon) for gamma-rays indicating violations of the nuclear test ban treaty with the (then) Soviet Union. Seeing nothing from the Earth, the Los Alamos scientists looked for any other signal...
Terrestrial Gamma Flashes have been detected by orbiting instruments for some time; at least since 1991,iirc. What's new here is the definite signature of positron annihilation; this can only be done with a sufficiently large detector looking at the right energy. The Burst Monitor on Fermi was designed to catch the medium energies of gamma-ray bursts (as well as low- and high energies), so this was a nice add-on to the main science.
"I have discovered a truly marvellous formal proof of this OS, which this sig is too narrow to contain"
For a change it would be nice to see NASA give kudos to whatever contractor built the successful spacecraft for them. Umm. some of NASA's spacecraft are delivered to the agency in-orbit, after checkout. Until then, they remain the property of the contractor. This is the case with GLAST, which was just launched, but will remain with General Dynamics until L+60 days.
Homeland Security Presidential Directive 12 has far-reaching implications. I am a state university research professor and receive funding from a NASA project. Even though I am a Co-Investigator on this project, I was told by my own management and University counsel that I would not be allowed access to my own data, should I refuse to sign, and thus cut myself off from my own funding. Fired, in other words. Needless to say, I signed.
As far as I can determine, HSPD-12 applies to *all* Gov't. agencies that supply computer network support. Now, imagine trying to get a foreign national on such networks for international collaboration...
Your tax dollars (US citizens only!) are now being spent investigating me and all my colleagues, so that we can continue to have the NASA computer accounts we've already held for years.
GammaRay Rob
Although Einstein wanted to show that Mach's Principle applied to the universe (which is what the Parent Poster was implying), he couldn't make it work in the framework of General Relativity. Essentially, we only feel the net force of matter within our horizon (defined loosely as the portion of the Universe visible to us since the beginning of time) and move accordingly. A portion of the Universe with net angular momentum that is non-zero is not ruled out in GR, spiral galaxies are an example on one length scale; this new result carries this to a much larger scale!
Why, yes, I *am* a rocket scientist (actually, an astrophysicist).
Sneaking in under the radar has been the iTunes Store from Apple. It is a desktop app; no, it is a web-based app. Actually, it is both, and a very successful model for the future.
... three members of NASA's advisory panel resigned for telling Griffen what he didn't want to know: that NASA is stealing money from science. Two of these were asked outright to leave and the other quit in sympathy (check NASA watch). To paraphrase: NASA doesn't need anyone to comment on current policy. Yet another example of how far Griffen has fallen to support the Bush adminitration's 'NASA as feeder for the aerospace business' policy. Sure, we'll get cargo to space, but it will consist of McDonalds (tm) hambugers for the ISS. Sorry I'm so bitter about this, but there goes your tax dollars (US readers!). Think of what $500 million US could do for the shrinking portion devote to the NASA science budget; which, by the way, has helped to fund the current and next generations of astronomy and astrophysics researchers in the US. Given the nature of the research, that helped everyone by advancing fundamental science research.
If we are truly able to upload or create or model intelligences in AI, they will be subject to *exactly* the same kind of boredom that we would experience. Otherwise, they would not be fair copies! Even worse, these intelligences would have no bodies for eating, drinking, or doing any of the tasks *we* might do to relieve the tedium. At best, you could turn them off until they reach their destination and hope that the `On' switch survives the trip!
GRR
Wait, aren't we talking at the speed at which we "travel" into time? I think the meaning of dt/dt is to say that time can only appear to go at always the same rate
This is where the original article has lead everyone astray: in GR (General Relativity), only the dx, dy, dz, and dt have meaning, not any of their ratios. In fact, in the broadest interpretation of GR, there is no special place for dt, it is just one of four mixed coordinates. Velocities are all (wait for it!)... relative. I've been reading a lot about this lately, which is why the simplistic tone of the article really grates on me.
You describe spacial travel as the dx, not the dx/dt. It stands to reason that you would describe time travel with the dt, not as some rate of travel we haven't come up with yet.
I *am* a physicist, and this guy just holed the article in one line. Good one!
...or the terrorists win!
OK. I am also an astrophysicist, and I have been studying gravity in its string theory and loop quantum guises. Gravitational waves carry information, so they will *not* come out of a black hole horizon. However, gravity (as expressed in the theory of General Relativity) obeys what is called Gauss's law, which just means to say that it doesn't matter (!) what lies beneath the spherical BH horizon, or *any* imaginary sphere that surrounds it, gravity only depends upon the total mass (or equivalent energy) contained within. No gravitons need escape the BH horizon to create the gravity equivalent to the mass gobbled up by the hole.
- GRR
It's funny!
Redundant, sheesh....
-GRR
How can we prevent being fried?
Make sure there's an atmosphere! We have survived being right next to an inconstant star for quite some time. Some of those recent X-class solar flares have been quite fierce.
GRR
As soon as it gets to the point where it becomes a re-entry risk (which happens when only one gyro remains functional), NASA will drop it into the Pacific. They don't want to risk an unplanned, uncontrolled descent that may put it in the middle of a population area.
Except, of course, it currently has no de-orbit capability, hence the plan to go there and add it. But, if you already have to go there...
But that's the wrong way to go. Microsoft, Apple, and other vendors need to figure out how to create software platforms that allow good integration between applications that weren't developed by a single team. And none of them have managed that yet.
True integration requires open, flexible standards for content and inter-application communications. Nobody has really figured out how to do that yet, least of all Microsoft and Apple.
This is a good point. Apple developed something called OpenDoc, which consisted of object-oriented documents with plug-in replaceable reader and content generator code. That way, if you didn't like the text editor, you simply bought another that worked the way you wished. BBEdit had a module that replaced the one Apple shipped. IIRC, ODoc was killed in a MS-Apple deal that left Office running on Macs...
Another story about how slow those Apples are!
If the parent isn't modded up +5 Funny, then Belgium Slashdot!!!
The Dublin conference talk isn't old news, but the possibility that Hawking was wrong has been growing for some time. General Relativity is, after all, a classical theory, which means that it must be invalid at high gravitational field strengths, such as you might find at the center of any black hole. It was shown some time ago by Polchinski (sp?) that certain aspects of string theory allow for enough freedom to solve the informational problem and, at the same time, account for the black hole entropy theorem. Thus, it was said that the center of each black hole harbors a 'stringularity'.
Damn! I just used up my last moderator point. I could have modded this down to (-1) Troll!!!
As the saying goes:
The box said, "Use Windows 98 or better", so I bought a Mac.
If we don't get a good fuel before the price of oil jacks up, then the only viable form of transportation is going to be electric rail, which is fine for dense areas, but is bad news for the US.
Umm, before the price of oil jacks up?!?
You're wrong. Aether was thought to be a physical fluid whose ripples were the basis of the wave-like nature of light. This was proven not to be so by Michelson and Morely, who showed that the speed of light was the same no matter if it were going with or against the aether (which was presumably flowing past the moving Earth). Dark energy is a field, like light or gravity, which presumably has no preferred frame of reference (like light or gravity).