No, they didn't. The idea that Pluto's atmosphere will freeze out over the next few decades is apparently probably not accurate. The leader of my research group has one of the two competing Pluto mission proposals, and he shared that finding with us a few months ago at a group meeting. Another interesting thing they found was that you can always go to Pluto for a reasonable price, propulsion wise. There are at least one or two gravity assists every year from Venus alone. Jupiter is preferable, of course, but not required.
The really neat thing from my point of view is that no matter which team wins the mission, people in my department will be on the science team.
I just saw them from within Boulder, CO (40 degrees N latitude). Yes, from inside Boulder proper, despite the city lights. So darker sky sites should have better luck. They were pretty identifiable as a pale green glow to the north. Unfortunately, they appear to be fading, now. So go out now!
I'm a bit miffed that Dr. Masters (gosh, that looks weird, doesn't it?) is already guessing that this is reasonsible for a fall of civilizations when he hasn't even dated the site yet. Perhaps it's just the tone that the authors of the authors of the article opted to take, but it's premature to be claiming this is the cause of the events it is being blamed for.
Of course, getting into Iraq to take samples and date the crater will not likely happen soon.
I think it's a bit blithe to state that we mammals are more fit than dinosaurs were. They were the dominant life on the planet for tens of millions of years, long than mammals have been running the show and much longer than humans have been around. If we were, in fact, superior in some way, why did it take a comet impact to give us our chance to shake them loose? I would have thought that given tens of millions of years, another, less violent, oppurtunity would have presented itself.
It's also worth remembering that in all probability, dinosaurs have direct descendents alive and well today. So they aren't exactly totally gone as just smaller and more feathered.
We wouldn't see radiation moving away from us. The SN that triggered the formation of our Solar System (if there was one) is well past dispersed by now, 4.55 billion years later. And it wouldn't be uniform in all directions at the predicted temperature of 3 K. Also, you need to explain why it's so uniform in different directions (once you account for Earth's known motions). A local source would tend to create a non-isotropic pattern.
I can't believe that, since the Earth, if compressed sufficiently, would only make a black hole less than 1 cm across. So if a 1 cm black hole swollowed the entire Earth, it would only be 2 cm across. Not big enough to have consumed the entire Earth by a long shot. The extra mass in the center of the planet would lead to some additional compression and a bit of extra feeding of the black hole, but not enough I should expect.
In any event, a mini-black hole would make a tiny puncture in the Earth. It would have to be well smaller than 1 cm, since a 1 cm radius black hole would have an Earth-mass and we'd have felt that go by as a jolt over the entire planet (not to mention the wicked tides). A puncture a micron across, for example, would never be noticed.
Creating protons isn't really nuclear as it's usually thought of. And the formation of atoms didn't occur for quite some time after the Big Bang. In any event, the term 'nuclear' completely fails to encompass the nature of the Big Bang, since 'nuclear' has nothing to do with the creation of spacetime.
I think you're misunderstanding the evidence for the Big Bang. We can see that galaxies are moving away from us, in accordance with Hubble's Law. We know that they are moving away from the Doppler effect: they are reddened (or they are abiding by totally different laws of physics). This means that whatever theory you adopt, it has to account for this apparent motion. This is pretty tricky, when you think about it. It has been attempted. Hoyle and others tried to create a steady state universe, with no beginning and no end. But when the measurements started coming in, the Big Bang started winning out (in addition to the fact that the steady state model was never really liked on purely aesthetic grounds). For example, the Big Bang correctly predicted the Cosmic Microwave background. (If the universe had always existed, where would it have come from?) The Big Bang also correctly predicts the relative fraction of elements in the universe. So any theory you come up with will be going toe-to-toe with a pretty beefy theory, depsite many claims to the contrary.
A better to way to date the universe than using the method of your second paragraph would be to simple figure out the Hubble Constant, this allowing us to figure out the current rate of expansion. Playing the problem backwards gives an age for the universe. The trouble with your method is that there is no clear way to date how old the stars you see are. Light doesn't age as it moves through the cosmos, remember.
Now, dark matter... It's called dark matter because we cannot see it with light gathering telescopes. But we can detect it. If it were not present, galaxies would be flying apart according to understood laws of physics. Similarly, galactic clusters would disperse. So it isn't like we can't detect the dark matter. It's like extra-solar planets. We've detected most of them indirectly by watching their stars. Still, most people think they are there.
According to the leading theory, an enormous nuclear explosion called the Big Bang happened 13 billion to 15 billion years ago.
Gack. How do they figure an explosion of spacetime is nuclear? There were no nuclei to fuse or split. My cynicism is telling me that the author just though "nuclear" sounded big and bang-y.
That's actually a fantastically good question. Unfortuantely, it's also one that we have no equipment to answer right now. Since we have no measurements of time before our universe (time didn't exist, at least not our time), we can't really apply the scientific method to that question. Maybe someday, we'll figure out a way of constraining theories about the "meta-universe" in which our universe is embedded. But for now, it's complete speculation and essentially not science.
Black holes have no magnetic fields. If their parent stars had had magnetic fields, they would be radiated away upon formation of the black hole (see the "no hair" theorem).
The material around a black hole in the accretion disk, however, can have a magnetic field. In fact, odds are pretty good that it will.
Not quite right: Mercury (and the Moon) have atmospheres composed mainly of sodium, potassium and oxygen blown off of the surface rocks. Hydrogen would escape via thermal means very rapid off of both worlds, as would helium.
I should defend Bob Pappalardo since I was on the committee that recommended his hiring here at CU and because otherwise my officemate (his grad student) will throw something heavy at me.
Bob's thesis was done years ago, the mid-90's as I recall, so I don't know why the press is just picking this up now. I have a hard time imaging that it's Bob's fault as much as the media's odd way of getting interested in things. Still, it is important work even if it did only show that Miranda probably wasn't broken apart, simply because removing one theory makes the research field that much smaller and easier to handle.
That said, the article is misleading. Bob's contention is seriously different from the beaking up hypothesis, because he believes Miranda suffered slow geological processes over long time periods, similar to processes seen on Earth. The smashing theory would have been a much more sudden event, not akin to anything in terrestrial geology. Bob's contention avoids the stochastic nature of the old theory, as well as allowing us to use what we know from Earth to study Miranda.
It's also worth noting that it had been known that Miranda could have been tidally heated since the late 80's, when Murry, Dermott and Malhorta published a paper on this topic. I got the sense for the article that Bob's work had come first, and the tidal study later, but this isn't the case.
Actually, it's quite easy to tell the difference with a few good measurments. Jupiter's magnetic field is tilted 10 degrees from the spin axis, so that Io, in the spin equator of Jupiter, is moving not just azimuthally through Jupiter's field as it passes over Io (10 hour period vs a 42 hour period for Io's orbit), but also up and down in the field. This means that the induced field will vary at different times. This is how they detected induced magnetic fields in Europa, Ganymede and Callisto (in these cases, the field strengths and compostions of the bodies point to liquid water).
The article hints at, but doesn't really explain, that the principle goal here is to find out of Io has an intrinsic or induced magnetic field. If the field is induced from Io's moment through Jupiter's whomping-string field (actually, the latter moves over Io more than anything, but whatever), then the south polar pass will show a different field signature than if the field is intrisically due to the internal workings of Io's core (a molten, convecting core ought to be able to create a field).
Last time Galileo tried this, it suffered a glitch just prior to closest approach. The magnetometer was turned out late in the restart sequence (which was probably a poor decision), so we didn't get the data two years ago. (This fly-by has been dubbed the 'cry-by' by several researchers I know.)
Let's just hold the poor, battered warrior survives this one.
Indeed, it could possibly harbor life. But the probability is much lower than Europa harboring life. So NASA and the Galileo mission planners made a choice: crash into Jupiter a very low risk vs. crash into Europa at a significantly higher risk.
More to the point, if Galileo, which is NOT fully decontaminated of Earth bacteria, hits Europa and gets under the ice (either now or in a few thousand years via tectonics), the WHOLE ecosystem is contaminated, since it's all interconnected quite readily. Jupiter is presumed to have no life, since there is very little for it to use to build organic molecules. So Jupiter is a safe target to hit.
NASA, and other international groups, has already thought of that and long ago addressed it. Even the Apollo missions were carried out so that the Moon rocks were kept in a quarantine, at negative relative pressure. Scientists worked with them via those glovey things you see in labs. Admittedly, the Apollo mission's planetary protection was done rather half-heartly (I won't regale you with stories, here). But Mars is taken a lot more seriously, as is Europa (Europa is the reason that Galileo is being sent to crash into Jupiter while we still have control of it, rather than let it continue to orbit indefinately). Any Mars mission has be decontaminated to where they're gauged as having less than 1 change in 10,000 of contaminating Mars. Martians samples are to be treated as hazardous until we are certain they are not.
No, you don't get the same information. The lab equipment on Earth is far superior to what we can get onto a spacecraft. Ultimately, is it cheaper to ship the lab to Mars, or the samples to Earth? (Answer: the latter.)
Additionally, having people actually handling the rocks is more important that you might think. People are intereactive, able to notice things not thought about during mission planning, then able to persue those questions. If you built a probe, you make a set of assumptions about what kinds of instruments you need and tests you'll do. You have to limit yourself more than you would if you have a person actually handling the rocks.
The fullest continuation of this logic is that we ultimately will want to put people on Mars for these same reasons. However, we're nowhere near ready for that at this time.
Oh, no. It's getting a nice severence package, including a small, but helpful, pension, stocks and it can keep that little beach place in the Bahamas if it likes. Except there was this clause about having to show up in person to claim the stocks and checks.
A black hole can only consume as much matter as it can reach. Its gravity doesn't have some magical proerpty that allows it to yank stars out of their orbits, so the feeding slows to a near halt after a while. This is why the Milky Way does not poesses an active nucleus like many younger, distance galaxies appear to.
n this aspect you are right - without such an object the Milky Way could not exist as it does now, as there would be nothing stronger than the attraction between solar systems to hold it together.
The attraction between stars would be quite enough to hold the galaxy together. For decades, galactic researchers didn't have any reason to think that there was a black hole at the center of our galaxy. They never needed it to hold things together; after all, the black holes looks just like 3 million solar mass stars in the galactic nucleus to our Sun.
By way of analogy, globular clusters are hold themselves together without black holes in their cores (N-body simulations indicate that they are, in fact, dynamically stable). And there is at least one case of a galaxy that probably does not have a black hole in its nucleas. All tests have come up negative for it.
The fact that the Milky Way is a spiral demonstrates that the orbit is degrading.
Not really, no. The spiral structure of galaxies has nothing to do with "spriralling down the hole." It's probably some time of density wave phenomenon, stable and self-perpetuating. The orbits of individual stars and gas clouds are basically stable, Keplerian orbits.
Even if the black holes 'eats' all of the stars in its area, it won't affect the Sun's orbit about the galactic center. All the that Sun sees at this distance is how much mass is as close to the galactic center as it is or closer. What form that that matter is in turns out not to matter. Black holes don't get really wacky, graviationally speaking, until you get close to them. This is exactly why they are so hard to identify with the existing data.
Slashdot Mirror
No, they didn't. The idea that Pluto's atmosphere will freeze out over the next few decades is apparently probably not accurate. The leader of my research group has one of the two competing Pluto mission proposals, and he shared that finding with us a few months ago at a group meeting. Another interesting thing they found was that you can always go to Pluto for a reasonable price, propulsion wise. There are at least one or two gravity assists every year from Venus alone. Jupiter is preferable, of course, but not required.
The really neat thing from my point of view is that no matter which team wins the mission, people in my department will be on the science team.
I just saw them from within Boulder, CO (40 degrees N latitude). Yes, from inside Boulder proper, despite the city lights. So darker sky sites should have better luck. They were pretty identifiable as a pale green glow to the north. Unfortunately, they appear to be fading, now. So go out now!
I'm a bit miffed that Dr. Masters (gosh, that looks weird, doesn't it?) is already guessing that this is reasonsible for a fall of civilizations when he hasn't even dated the site yet. Perhaps it's just the tone that the authors of the authors of the article opted to take, but it's premature to be claiming this is the cause of the events it is being blamed for.
Of course, getting into Iraq to take samples and date the crater will not likely happen soon.
I think it's a bit blithe to state that we mammals are more fit than dinosaurs were. They were the dominant life on the planet for tens of millions of years, long than mammals have been running the show and much longer than humans have been around. If we were, in fact, superior in some way, why did it take a comet impact to give us our chance to shake them loose? I would have thought that given tens of millions of years, another, less violent, oppurtunity would have presented itself.
It's also worth remembering that in all probability, dinosaurs have direct descendents alive and well today. So they aren't exactly totally gone as just smaller and more feathered.
We wouldn't see radiation moving away from us. The SN that triggered the formation of our Solar System (if there was one) is well past dispersed by now, 4.55 billion years later. And it wouldn't be uniform in all directions at the predicted temperature of 3 K. Also, you need to explain why it's so uniform in different directions (once you account for Earth's known motions). A local source would tend to create a non-isotropic pattern.
I can't believe that, since the Earth, if compressed sufficiently, would only make a black hole less than 1 cm across. So if a 1 cm black hole swollowed the entire Earth, it would only be 2 cm across. Not big enough to have consumed the entire Earth by a long shot. The extra mass in the center of the planet would lead to some additional compression and a bit of extra feeding of the black hole, but not enough I should expect.
In any event, a mini-black hole would make a tiny puncture in the Earth. It would have to be well smaller than 1 cm, since a 1 cm radius black hole would have an Earth-mass and we'd have felt that go by as a jolt over the entire planet (not to mention the wicked tides). A puncture a micron across, for example, would never be noticed.
Creating protons isn't really nuclear as it's usually thought of. And the formation of atoms didn't occur for quite some time after the Big Bang. In any event, the term 'nuclear' completely fails to encompass the nature of the Big Bang, since 'nuclear' has nothing to do with the creation of spacetime.
I think you're misunderstanding the evidence for the Big Bang. We can see that galaxies are moving away from us, in accordance with Hubble's Law. We know that they are moving away from the Doppler effect: they are reddened (or they are abiding by totally different laws of physics). This means that whatever theory you adopt, it has to account for this apparent motion. This is pretty tricky, when you think about it. It has been attempted. Hoyle and others tried to create a steady state universe, with no beginning and no end. But when the measurements started coming in, the Big Bang started winning out (in addition to the fact that the steady state model was never really liked on purely aesthetic grounds). For example, the Big Bang correctly predicted the Cosmic Microwave background. (If the universe had always existed, where would it have come from?) The Big Bang also correctly predicts the relative fraction of elements in the universe. So any theory you come up with will be going toe-to-toe with a pretty beefy theory, depsite many claims to the contrary.
A better to way to date the universe than using the method of your second paragraph would be to simple figure out the Hubble Constant, this allowing us to figure out the current rate of expansion. Playing the problem backwards gives an age for the universe. The trouble with your method is that there is no clear way to date how old the stars you see are. Light doesn't age as it moves through the cosmos, remember.
Now, dark matter... It's called dark matter because we cannot see it with light gathering telescopes. But we can detect it. If it were not present, galaxies would be flying apart according to understood laws of physics. Similarly, galactic clusters would disperse. So it isn't like we can't detect the dark matter. It's like extra-solar planets. We've detected most of them indirectly by watching their stars. Still, most people think they are there.
Gack. How do they figure an explosion of spacetime is nuclear? There were no nuclei to fuse or split. My cynicism is telling me that the author just though "nuclear" sounded big and bang-y.
That's actually a fantastically good question. Unfortuantely, it's also one that we have no equipment to answer right now. Since we have no measurements of time before our universe (time didn't exist, at least not our time), we can't really apply the scientific method to that question. Maybe someday, we'll figure out a way of constraining theories about the "meta-universe" in which our universe is embedded. But for now, it's complete speculation and essentially not science.
Doesn't work, since black holes have no intrinsic magnetic fields of their own, by the "no hair" theorem.
Black holes have no magnetic fields. If their parent stars had had magnetic fields, they would be radiated away upon formation of the black hole (see the "no hair" theorem).
The material around a black hole in the accretion disk, however, can have a magnetic field. In fact, odds are pretty good that it will.
Not quite right: Mercury (and the Moon) have atmospheres composed mainly of sodium, potassium and oxygen blown off of the surface rocks. Hydrogen would escape via thermal means very rapid off of both worlds, as would helium.
A circle is just a degenerate ellipse that is easier to draw.
I always balk at unbound trajectories "orbits". It goes against my perceived meaning of the word, somehow.
Perhaps by "looping" the press release was refering to how the orbit won't be closed? Yeah, I doubt that they were being that subtle, too.
I should defend Bob Pappalardo since I was on the committee that recommended his hiring here at CU and because otherwise my officemate (his grad student) will throw something heavy at me.
Bob's thesis was done years ago, the mid-90's as I recall, so I don't know why the press is just picking this up now. I have a hard time imaging that it's Bob's fault as much as the media's odd way of getting interested in things. Still, it is important work even if it did only show that Miranda probably wasn't broken apart, simply because removing one theory makes the research field that much smaller and easier to handle.
That said, the article is misleading. Bob's contention is seriously different from the beaking up hypothesis, because he believes Miranda suffered slow geological processes over long time periods, similar to processes seen on Earth. The smashing theory would have been a much more sudden event, not akin to anything in terrestrial geology. Bob's contention avoids the stochastic nature of the old theory, as well as allowing us to use what we know from Earth to study Miranda.
It's also worth noting that it had been known that Miranda could have been tidally heated since the late 80's, when Murry, Dermott and Malhorta published a paper on this topic. I got the sense for the article that Bob's work had come first, and the tidal study later, but this isn't the case.
Actually, it's quite easy to tell the difference with a few good measurments. Jupiter's magnetic field is tilted 10 degrees from the spin axis, so that Io, in the spin equator of Jupiter, is moving not just azimuthally through Jupiter's field as it passes over Io (10 hour period vs a 42 hour period for Io's orbit), but also up and down in the field. This means that the induced field will vary at different times. This is how they detected induced magnetic fields in Europa, Ganymede and Callisto (in these cases, the field strengths and compostions of the bodies point to liquid water).
The article hints at, but doesn't really explain, that the principle goal here is to find out of Io has an intrinsic or induced magnetic field. If the field is induced from Io's moment through Jupiter's whomping-string field (actually, the latter moves over Io more than anything, but whatever), then the south polar pass will show a different field signature than if the field is intrisically due to the internal workings of Io's core (a molten, convecting core ought to be able to create a field).
Last time Galileo tried this, it suffered a glitch just prior to closest approach. The magnetometer was turned out late in the restart sequence (which was probably a poor decision), so we didn't get the data two years ago. (This fly-by has been dubbed the 'cry-by' by several researchers I know.)
Let's just hold the poor, battered warrior survives this one.
Indeed, it could possibly harbor life. But the probability is much lower than Europa harboring life. So NASA and the Galileo mission planners made a choice: crash into Jupiter a very low risk vs. crash into Europa at a significantly higher risk.
More to the point, if Galileo, which is NOT fully decontaminated of Earth bacteria, hits Europa and gets under the ice (either now or in a few thousand years via tectonics), the WHOLE ecosystem is contaminated, since it's all interconnected quite readily. Jupiter is presumed to have no life, since there is very little for it to use to build organic molecules. So Jupiter is a safe target to hit.
NASA, and other international groups, has already thought of that and long ago addressed it. Even the Apollo missions were carried out so that the Moon rocks were kept in a quarantine, at negative relative pressure. Scientists worked with them via those glovey things you see in labs. Admittedly, the Apollo mission's planetary protection was done rather half-heartly (I won't regale you with stories, here). But Mars is taken a lot more seriously, as is Europa (Europa is the reason that Galileo is being sent to crash into Jupiter while we still have control of it, rather than let it continue to orbit indefinately). Any Mars mission has be decontaminated to where they're gauged as having less than 1 change in 10,000 of contaminating Mars. Martians samples are to be treated as hazardous until we are certain they are not.
Additionally, having people actually handling the rocks is more important that you might think. People are intereactive, able to notice things not thought about during mission planning, then able to persue those questions. If you built a probe, you make a set of assumptions about what kinds of instruments you need and tests you'll do. You have to limit yourself more than you would if you have a person actually handling the rocks.
The fullest continuation of this logic is that we ultimately will want to put people on Mars for these same reasons. However, we're nowhere near ready for that at this time.
Oh, no. It's getting a nice severence package, including a small, but helpful, pension, stocks and it can keep that little beach place in the Bahamas if it likes. Except there was this clause about having to show up in person to claim the stocks and checks.
A black hole can only consume as much matter as it can reach. Its gravity doesn't have some magical proerpty that allows it to yank stars out of their orbits, so the feeding slows to a near halt after a while. This is why the Milky Way does not poesses an active nucleus like many younger, distance galaxies appear to.
The attraction between stars would be quite enough to hold the galaxy together. For decades, galactic researchers didn't have any reason to think that there was a black hole at the center of our galaxy. They never needed it to hold things together; after all, the black holes looks just like 3 million solar mass stars in the galactic nucleus to our Sun.
By way of analogy, globular clusters are hold themselves together without black holes in their cores (N-body simulations indicate that they are, in fact, dynamically stable). And there is at least one case of a galaxy that probably does not have a black hole in its nucleas. All tests have come up negative for it.
The fact that the Milky Way is a spiral demonstrates that the orbit is degrading.
Not really, no. The spiral structure of galaxies has nothing to do with "spriralling down the hole." It's probably some time of density wave phenomenon, stable and self-perpetuating. The orbits of individual stars and gas clouds are basically stable, Keplerian orbits.
Even if the black holes 'eats' all of the stars in its area, it won't affect the Sun's orbit about the galactic center. All the that Sun sees at this distance is how much mass is as close to the galactic center as it is or closer. What form that that matter is in turns out not to matter. Black holes don't get really wacky, graviationally speaking, until you get close to them. This is exactly why they are so hard to identify with the existing data.