Gamma and X-Ray are what's known as "cosmic rays" because they are prevalent in background radiation.
This is a common misconception. I learned the real meaning of the term from an astronomy professor just a few weeks ago. Most people who know the term think that it means really high energy EM radiation, like X-rays or gamma rays, but in fact they are high-energy charged particles. They are frequently protons, but can also be nuclei of almost any element. They can be big, heavy nuclei moving at quite nearly the speed of light.
It turns out that almost all Boron and Beryllium in existence is formed when a cosmic ray nucleus like carbon, oxygen, or nitrogen smacks into an interstellar gas atom like hydrogen and breaks apart (it's called spallation). Only trace amounts of B and Be were produced during the nucleosynthesis phase after the big bang, and only trace amounts are produced in supernovae.
What about a conversation held by a series of paper snail-mail letters? Is it illegal to save those letters? I don't think so. A chat room is basically the same thing, just instant and electronic. Rather than sending a stream of sound information (phone) they are giving you an electronic copy of text that they have written. I can't see how this law applies, but I guess I'm not a lawyer.
Note: I am a physics undergrad with some galactic dynamics / astronomy / cosmology education.
What if this is only a *very* good approximation for all normal purposes, and even for things as large as the solar system (in the same way that Newtonian mechanics is good enough for all earthly based stuff).
What if gravity doesn't quite work this way at galactic scales?
This is a possibility that is NOT being ignored by the astrophysics community. There have been several attempts (presumably like the one you reference, though I haven't checked it out) to modify gravity theories much like you say. Up close they predict the orbits of planets and such very well, but over longer distances they change the behavior of gravity as to match some of the observations. The problem with them thus far is that they fail to explain every observed system, such as galaxy interactions and clustering. They can only get some parts to work, not all. This doesn't imply, however, that there is no such theory, it is entierly possible that we haven't thought of it yet.
Several decades ago, the Big Bang theory wasn't universaly accepted by the cosmology community. Another thoery, the Steady State Theory had about as big of a following. Over time though, holes and failed predictions started showing up, and they kept mounting and mounting, while the Big Bang theory kept matching new observational discoveries. It has been modified now and then (like by adding inflation), but the basic concept is still the same, and now it is thought to be true (or at least the general idea) by the vast majority of cosmologists. The mountain of observational evidence is impossible to ignore. The weaker theory has been weeded out, and the consistent one has thrived.
Maybe a new theory of gravity or some other theory will come forth that explains the same thing that Dark Matter does, and maybe it will have correct predictions where dark matter fails. If that is the case then Dark Matter will be all but cast aside. It seems extremely unlikely though, since several entierly different sources have had the same predictions for dark matter / dark energy breakdowns. Observations of type Ia supernovae in distant galaxies gave the first major hints that the universe expansion is accelerating. It gave values for the relative amounts of dark matter and dark energy. A totaly unrelated observation (WMAP) of something with no relationship to type Ia supernovae gave effectivly the same results. Big Bang Nucleosynthesis theory starts with very few premises and derives a the same ratios of various mass particles that WMAP and other more conventional observations show. It would take something truly extrodanry to overthrow this theory.
But who knows? It can still happen. The community really is open to it, if a good theory comes forth, though they have gotten comfortable where they are.
I read through all the computer policy crap that Fermilab has when I got my computer account there (worked on the CDF experiment a tad). It is their policy that no computers that control systems which could cause personal or environmental harm are connected to the internet. Further, any computer being used to write software that controls these systems can not be connected to the internet.
As others have already pointed out, there is no classified information at Fermilab. It is research done to expand human knowledge, and everything learned there is made public.
Will someone else come along and show that we don't understand gravity sufficiently, and postulate a theory that will eliminate the need for dark matter and energy?
When observation does not match theory, then either the observation is wrong, the thoery is wrong, or both are wrong. The observed mass of the Galaxy is not enough to do what is seen, based on current gravity theory. If we assume that the observed mass is wrong, and add in dark matter, everything seems to work out fine. The problem is that (excepting this paper) searches for dark matter have thus far failed. If we assume that the theory of gravity is wrong, one can try to cook up new thoeries that make everything work out for the Galaxy. The problem is, or so a dark matter researcher told me, that so far those theories don't correctly explain what happens in groups of galaxies.
So the end result will be that there is dark matter, general relativity is wrong or flawed, or some combination of the two. Observation, experiment, and theoretical work will decide the issue, that's what science is all about.
I'm assuming that the "troll" rating you got earlier was a misrepresentation, since you haven't been rated as one recently.
Earth spins at a constant angular rate. By using a 100,000 km ribbon, the velocity at the end is... 7.27 km/sec. Also, you'll note that as you get further out the force from gravity decreases. At that distance, the acceleration due to gravity is around 1/500 the gravity at the surface of the earth.
You'll notice that planets further from the sun orbit at much lower angular velocities, a couple of hundredths the rate of earth.
Another example is the Moon. It is a few hundred thousand km away, but it takes 28 days to move around the earth. This thing will be a good chunk of that distance and spin 28 times faster. Seems like plenty to me.
Satellites in low earth orbit go around once every 90 minutes or so, but ones in the much higher geosynchronous orbits go around only once per day.
I was commenting on the point that the whole argument of your original post was "It's illegal, so he should be arrested". I didn't get outside of that, so calm down.
He was violating the law......and were glad to have them fixed, what he did was still illegal. He should deserve to be arrested...
Are you saying that everything one does to break the law is bad and should be punished? The law is an approximation of morality. It's that whole stealing bread to feed your starving children thing. Not wrong, but illegal. I'm not saying that this guy's reasons are as pure as that, but just because it is illegal doesn't mean it is wrong. If I loose my Windows CD but need to re-install my OS, is it wrong to use a pirated copy of the same version? It's illegal, but I'd say that it is most definitely not bad.
If I jaywalk to stop a little kid from running into traffic, should I be fined?
If you would have RTFA before posting, you would know that they aren't saying that at all.
While the exact details are still being debated by theorists, the researchers' own theoretical considerations suggest the presence of short-lived (sub-femtosecond) entanglement, in which protons in adjacent hydrogen atoms (and possibly the surrounding electrons) are all interlinked in such a way as to change the nature of the scattering results. Realizing that water itself has anomalous properties, the researchers repeated the neutron experiments in other more typical molecules, for instance in benzene (conventionally noted as C6H6). In that case, they found that the neutrons saw a ratio of hydrogen to carbon of 4.5 to 6! Meanwhile, this effect was also confirmed in various hydrogen-containing metals, in a collaboration with Uppsala University in Sweden.
They are saying that maybe at attosecond time scales, maybe the adjacent hydrogen nuclei are entangled in such a way that fewer of them interact with the incoming particle, or something to that effect. To fully understand this probably requires a deeper knowlege of quantum mechanics and more detail than this article provides, but it is not without precident for many particles to behave as one. Check out Bose-Einstein condensates for info on that.
Another great place in Ohio, which is a little more nerdy, is the United States Air Force Museum at the Wright-Patterson Air Force Base in Dayton, Ohio. When I was there a few years ago, they had some of the most advanced aircraft ever made, including the XB-70, SR-71, YF-22, X-29, F-117, Tacit Blue, as well as some old favorites like an X-15, B-52, F-15A, A-10, B-1A, and F-16A. And MANY MANY more.
I don't know if I would clasify it as a "once in a lifetime" experience, but if you are at all interested in aircraft, it is simply glorioius to be able to go up to and touch these almost mythical planes.
The XB-70 is amazing, it doesn't even look like it should be able to exist.
To win the $10 million X Prize a spacecraft must be privately financed and constructed with the ability to fly three people 62 miles (100 kilometers) into space. It also must be reusable, flying twice within a two-week period.
They can use no money from the Israeli Gov., whether it be from Israeli or US taxpayers.
I am concerned about the recent setbacks in many scientific fields. With the loss of the Challenger, the crash of the Helios, and now this, it makes me wonder what next.
Hang on there cowboy. This probably just needs to be filed under the "Shit Happens" category. Spacecraft have always been blowing up because it is mighty difficult to build something that reliable goes through all that punishment. Experimental aircraft have always crashed, because they're experimental. You do experiments, and when something crashes you know what not to do. This sub was lost because it ended up in an extreme environment.
What's next? More spacecraft exploding, more experimental aircraft crashing, and engineers and scientists learning a lot from it. This isn't a fairy-tale world; pushing the boundaries of known science and engineering is bound to have some hic-ups and failures. Think of all the test pilots who have died, the scores rockets that blew up in the 50's and 60's, and the ships lost at sea hundreds of years ago. When the cabin of Apollo 1 burst into flames and killed three people, we didn't abandon the program, we just figured out what went wrong, fixed it, and moved on and landed on the moon what, seven times? That progress at the cost of a failure invigorated at least one nation and led to greater public interest in aerospace, without which Helios wouldn't even have a chance to fail.
It's just a proof of concept. Yeah, it sure would suck to be stuck in the front and have your horse trip, that would probably take out a significant fraction of the calvary.
If I remember correctly from the Silmarillion, the major reason why they had to choose was to determine what would happen when/if they die.
When Elves die, they go to the Halls of Mandos, on Arda (earth), where they wait for the end of the world. Elves truly are immortal, in that even if you slay them, they still exist in some form on Arda until the end.
It is different for the race of Men. When Men die, they do not go to the Halls of Mandos... I don't remember exactly what happens to them, but I think that nobody else on Arda did either. It was just said that they would have some part to play "in the end".
So I think that this was the reason that they had to choose, because Mandos wanted to be sure what would happen when they die.
By the way, Dwarves were never really meant to exist. One of the Valar, Aule (deity who made things of metal and stone), in slight defiance of Eru (The Creator) made the Dwarves that would enjoy the things that he did. I think that it is said that they "return to the stone" or something like that when they die.
At first I thought the same, but it turns out that horses CAN do that. I've had a few experienced horsemen look at that clip, and they claim that a well trained horse and experienced rider should have no problem charging down a hill that steep. Supposedly the Rohirrim are the best horsemen and have the best horses in middle earth.
Also, watch the movie Tombstone. There is a brief scene in which Wyatt Earp and someone else run their horses down an equaly steep, albiet smaller, hill. That wasn't CG.
Oh, that's nothing. You should see a 2-liter soda bottle filled with LN2 or dry ice. I think that the energy released is proportional to volume * pressure. I've learned from experience with this that soda bottles blow bigger than water bottles, because they're made to withstand internal pressure. Heck, even a 20 oz bottle is loud enough to make you think that you're being bombed.
NOTE: These explosions send plastic shards flying out FAST. I suggest the safest and most reliable set-up of tying bricks or a cinder block to the bottle and submerging it in water. Not only will the water help with stopping shards, it will act as a heat reseviour to heat the CO2/LN2 up fast enough to cause it to explode reliably. If you use a tall bucket or trash can, then all of the shrapnel will be directed upward.
If you want a REALLY good, reliable, and safe set-up for smaller than 1 liter bottles, try this: Get a large rubber trash can with a lid that snaps onto the top, but can be removed simply by puling on it (no fancy latches). Drill dozens of ~1-1.5 cm holes out of the lid, as many as you can get and still have it be strong. Place a bucket of water in the bottom of the trash can. Fill a bottle (20 oz soda bottles work wonderfully) ~ 1/3 full of Liquid Nitrogen or Dry Ice, and (very very quickly) put the cap on TIGHT, throw the damned thing into the bucket, slam the lid on the can tight, and run away screaming "FIRE IN THE HOLE" (safe distance > 20 feet). In 5-30 seconds, the bottle should blow, the gas and some water will fly out of the holes, and the lid will blow off and fly >10 feet up (watch out for power lines), and a single, beautiful sound will eminate from the beast, enthralling the onlookers while terrifying those who have no idea what just happened. The lid will stay on long enough to slow down the plastic shards to reasonable velocities, but they will still be scattered around the setup.
Disclamer: This is kinda dangerous, and maybe illegal (disturbing the peace). Do it at your own risk. LN2/Dry ice is COLD, sound is LOUD, shrapnel is FAST. Sometimes the bottle may take longer to blow (especialy if you put too little/too much cold stuff in it). If more than a minute or two passes, then... be carefull. The safest measure is to just let it sit for a LONG time. I've known these things to sit dormant for up to a half hour before going off. However, if you didn't put the cap on tight enough, the gas could have leaked out, and you have nothing more than a cold bottle that you should be afraid of. If you for some reason decide to take the lid off the can and look inside to see what's going on, wear some damn saftey glasses!
Wow, I didn't really mean to write more than the first paragraph, but I thought that I would get it all down for those interested.
Hmmm... here's an idea: If you use the plastic soda bottle variety you could somehow modify the cap so that it breaks before the rest of the bottle (maybe cut a circle in it that goes half way through). Pressure will build up and when the cap blows out you get a (very) brief and powerful rocket blast.
I perfer Liquid Nitrogen to dry ice. MUCH safer to handle, and there are many many many more cool things that you can do with it. At U of I, we use liquid nitrogen to make ice cream in seconds.
Good solid post, but I would like to make one little point (that doesn't change your argument):
Height has nothing to do with it. Orbit is achieved by virtue of velocity. While it can be argued that some satellites didn't need to be launched via the shuttle, it is silly to argue that satellites have been compromised by being ddiesinged to fit in the shuttle's cargo bay. All satellites must be designed to fit in the craft that launches them, whether a shuttle or an expendable booster.
For some scientific equipment (such as some observatories), a non-shuttle launch vehicle (such as a Delta) would be optimal to get it to the high orbit needed to get away from earth's interference. However, for some American projects, the government has required scientists to modify their designs to be launched with the shuttle rather than by the optimal launch vehicle. This sometimes means making it smaller to fit in the cargo bay, as well as allowing room for extra boosters to get the satellite to its desired orbit, decreasing the craft's capabilities.. More politics, just NASA trying to justify the shuttle program.
Note that I'm not saying anything bad about the shuttle. I think that it is a remarkable and useful craft, however its use shouldn't forced as it is.
No such neutrino exists, as far as anyone can tell.
The theorized neutrino, called the "sterile neutrino" is thought to potentially exist because the way that the mass differences add up for the other 3 neutrinos doesn't work out quite right. In current experiments, we can not detect the masses of neutrinos, only the squares of the differences of the masses between types of neutrinos. IIRC, there is 1 large difference and 2 small differences that can not add up to the first one. For this (and other) reasons they theorize the sterile neutrino's existence to make up for this extra gap.
Its existence does not imply a fourth generation of quarks and leptons, however.
This isn't widely accepted, but I heard it at a colloquium given by a neutrino physicist shortly after some of the big announcements on neutrino mass last year.
Slashdot Mirror
It turns out that almost all Boron and Beryllium in existence is formed when a cosmic ray nucleus like carbon, oxygen, or nitrogen smacks into an interstellar gas atom like hydrogen and breaks apart (it's called spallation). Only trace amounts of B and Be were produced during the nucleosynthesis phase after the big bang, and only trace amounts are produced in supernovae.
Fascinating stuff.
What about a conversation held by a series of paper snail-mail letters? Is it illegal to save those letters? I don't think so. A chat room is basically the same thing, just instant and electronic. Rather than sending a stream of sound information (phone) they are giving you an electronic copy of text that they have written. I can't see how this law applies, but I guess I'm not a lawyer.
This is a possibility that is NOT being ignored by the astrophysics community. There have been several attempts (presumably like the one you reference, though I haven't checked it out) to modify gravity theories much like you say. Up close they predict the orbits of planets and such very well, but over longer distances they change the behavior of gravity as to match some of the observations. The problem with them thus far is that they fail to explain every observed system, such as galaxy interactions and clustering. They can only get some parts to work, not all. This doesn't imply, however, that there is no such theory, it is entierly possible that we haven't thought of it yet.
Several decades ago, the Big Bang theory wasn't universaly accepted by the cosmology community. Another thoery, the Steady State Theory had about as big of a following. Over time though, holes and failed predictions started showing up, and they kept mounting and mounting, while the Big Bang theory kept matching new observational discoveries. It has been modified now and then (like by adding inflation), but the basic concept is still the same, and now it is thought to be true (or at least the general idea) by the vast majority of cosmologists. The mountain of observational evidence is impossible to ignore. The weaker theory has been weeded out, and the consistent one has thrived.
Maybe a new theory of gravity or some other theory will come forth that explains the same thing that Dark Matter does, and maybe it will have correct predictions where dark matter fails. If that is the case then Dark Matter will be all but cast aside. It seems extremely unlikely though, since several entierly different sources have had the same predictions for dark matter / dark energy breakdowns. Observations of type Ia supernovae in distant galaxies gave the first major hints that the universe expansion is accelerating. It gave values for the relative amounts of dark matter and dark energy. A totaly unrelated observation (WMAP) of something with no relationship to type Ia supernovae gave effectivly the same results. Big Bang Nucleosynthesis theory starts with very few premises and derives a the same ratios of various mass particles that WMAP and other more conventional observations show. It would take something truly extrodanry to overthrow this theory.
But who knows? It can still happen. The community really is open to it, if a good theory comes forth, though they have gotten comfortable where they are.
I read through all the computer policy crap that Fermilab has when I got my computer account there (worked on the CDF experiment a tad). It is their policy that no computers that control systems which could cause personal or environmental harm are connected to the internet. Further, any computer being used to write software that controls these systems can not be connected to the internet.
As others have already pointed out, there is no classified information at Fermilab. It is research done to expand human knowledge, and everything learned there is made public.
So the end result will be that there is dark matter, general relativity is wrong or flawed, or some combination of the two. Observation, experiment, and theoretical work will decide the issue, that's what science is all about.
I'm assuming that the "troll" rating you got earlier was a misrepresentation, since you haven't been rated as one recently.
Earth spins at a constant angular rate. By using a 100,000 km ribbon, the velocity at the end is... 7.27 km/sec. Also, you'll note that as you get further out the force from gravity decreases. At that distance, the acceleration due to gravity is around 1/500 the gravity at the surface of the earth.
You'll notice that planets further from the sun orbit at much lower angular velocities, a couple of hundredths the rate of earth.
Another example is the Moon. It is a few hundred thousand km away, but it takes 28 days to move around the earth. This thing will be a good chunk of that distance and spin 28 times faster. Seems like plenty to me.
Satellites in low earth orbit go around once every 90 minutes or so, but ones in the much higher geosynchronous orbits go around only once per day.
I was commenting on the point that the whole argument of your original post was "It's illegal, so he should be arrested". I didn't get outside of that, so calm down.
And there's no need to mark me as a foe...
If I jaywalk to stop a little kid from running into traffic, should I be fined?
Hey, could you post the full text? I don't have a subscription to the digital thing, only the paper copy, and only since june.
Sorry, but reading your comment it seemed like you were talking about the research itself and dismissing it out of hand.
Another great place in Ohio, which is a little more nerdy, is the United States Air Force Museum at the Wright-Patterson Air Force Base in Dayton, Ohio. When I was there a few years ago, they had some of the most advanced aircraft ever made, including the XB-70, SR-71, YF-22, X-29, F-117, Tacit Blue, as well as some old favorites like an X-15, B-52, F-15A, A-10, B-1A, and F-16A. And MANY MANY more.
I don't know if I would clasify it as a "once in a lifetime" experience, but if you are at all interested in aircraft, it is simply glorioius to be able to go up to and touch these almost mythical planes.
The XB-70 is amazing, it doesn't even look like it should be able to exist.
They can use no money from the Israeli Gov., whether it be from Israeli or US taxpayers.
Here's a recent possibility for a tetraquark.
What's next? More spacecraft exploding, more experimental aircraft crashing, and engineers and scientists learning a lot from it. This isn't a fairy-tale world; pushing the boundaries of known science and engineering is bound to have some hic-ups and failures. Think of all the test pilots who have died, the scores rockets that blew up in the 50's and 60's, and the ships lost at sea hundreds of years ago. When the cabin of Apollo 1 burst into flames and killed three people, we didn't abandon the program, we just figured out what went wrong, fixed it, and moved on and landed on the moon what, seven times? That progress at the cost of a failure invigorated at least one nation and led to greater public interest in aerospace, without which Helios wouldn't even have a chance to fail.
Wow, thanks! I may do that if I can fit in in my class schedule.
I'm an undergrad in physics at UIUC. Any jobs at your place open for the fall? Filling dewars or some such?
But come on, it's an epic movie.
When Elves die, they go to the Halls of Mandos, on Arda (earth), where they wait for the end of the world. Elves truly are immortal, in that even if you slay them, they still exist in some form on Arda until the end.
It is different for the race of Men. When Men die, they do not go to the Halls of Mandos... I don't remember exactly what happens to them, but I think that nobody else on Arda did either. It was just said that they would have some part to play "in the end".
So I think that this was the reason that they had to choose, because Mandos wanted to be sure what would happen when they die.
By the way, Dwarves were never really meant to exist. One of the Valar, Aule (deity who made things of metal and stone), in slight defiance of Eru (The Creator) made the Dwarves that would enjoy the things that he did. I think that it is said that they "return to the stone" or something like that when they die.
Also, watch the movie Tombstone. There is a brief scene in which Wyatt Earp and someone else run their horses down an equaly steep, albiet smaller, hill. That wasn't CG.
I don't get it...
Oh, that's nothing. You should see a 2-liter soda bottle filled with LN2 or dry ice. I think that the energy released is proportional to volume * pressure. I've learned from experience with this that soda bottles blow bigger than water bottles, because they're made to withstand internal pressure. Heck, even a 20 oz bottle is loud enough to make you think that you're being bombed.
NOTE: These explosions send plastic shards flying out FAST. I suggest the safest and most reliable set-up of tying bricks or a cinder block to the bottle and submerging it in water. Not only will the water help with stopping shards, it will act as a heat reseviour to heat the CO2/LN2 up fast enough to cause it to explode reliably. If you use a tall bucket or trash can, then all of the shrapnel will be directed upward.
If you want a REALLY good, reliable, and safe set-up for smaller than 1 liter bottles, try this: Get a large rubber trash can with a lid that snaps onto the top, but can be removed simply by puling on it (no fancy latches). Drill dozens of ~1-1.5 cm holes out of the lid, as many as you can get and still have it be strong. Place a bucket of water in the bottom of the trash can. Fill a bottle (20 oz soda bottles work wonderfully) ~ 1/3 full of Liquid Nitrogen or Dry Ice, and (very very quickly) put the cap on TIGHT, throw the damned thing into the bucket, slam the lid on the can tight, and run away screaming "FIRE IN THE HOLE" (safe distance > 20 feet). In 5-30 seconds, the bottle should blow, the gas and some water will fly out of the holes, and the lid will blow off and fly >10 feet up (watch out for power lines), and a single, beautiful sound will eminate from the beast, enthralling the onlookers while terrifying those who have no idea what just happened. The lid will stay on long enough to slow down the plastic shards to reasonable velocities, but they will still be scattered around the setup.
Disclamer: This is kinda dangerous, and maybe illegal (disturbing the peace). Do it at your own risk. LN2/Dry ice is COLD, sound is LOUD, shrapnel is FAST. Sometimes the bottle may take longer to blow (especialy if you put too little/too much cold stuff in it). If more than a minute or two passes, then... be carefull. The safest measure is to just let it sit for a LONG time. I've known these things to sit dormant for up to a half hour before going off. However, if you didn't put the cap on tight enough, the gas could have leaked out, and you have nothing more than a cold bottle that you should be afraid of. If you for some reason decide to take the lid off the can and look inside to see what's going on, wear some damn saftey glasses!
Wow, I didn't really mean to write more than the first paragraph, but I thought that I would get it all down for those interested.
Hmmm... here's an idea: If you use the plastic soda bottle variety you could somehow modify the cap so that it breaks before the rest of the bottle (maybe cut a circle in it that goes half way through). Pressure will build up and when the cap blows out you get a (very) brief and powerful rocket blast.
I perfer Liquid Nitrogen to dry ice. MUCH safer to handle, and there are many many many more cool things that you can do with it. At U of I, we use liquid nitrogen to make ice cream in seconds.
Note that I'm not saying anything bad about the shuttle. I think that it is a remarkable and useful craft, however its use shouldn't forced as it is.
No such neutrino exists, as far as anyone can tell.
The theorized neutrino, called the "sterile neutrino" is thought to potentially exist because the way that the mass differences add up for the other 3 neutrinos doesn't work out quite right. In current experiments, we can not detect the masses of neutrinos, only the squares of the differences of the masses between types of neutrinos. IIRC, there is 1 large difference and 2 small differences that can not add up to the first one. For this (and other) reasons they theorize the sterile neutrino's existence to make up for this extra gap.
Its existence does not imply a fourth generation of quarks and leptons, however.
This isn't widely accepted, but I heard it at a colloquium given by a neutrino physicist shortly after some of the big announcements on neutrino mass last year.