Put it on the border between the dark and light sides of the moon. Then, you can point it one way shoot stuff at Mars, and the other way to shoot stuff at Earth.
This would simply find what time the seismic waves from the quake reached the seismograph station. I'm talking about the time that the actual quake (ie. the snapping of the rock) occured at.
Do you know exactly how they get the time from the empirical graphs? Your explanation makes a fair bit of sense, but as far as I know the graphs of P and S wave can't be used to determine the time.
Maybe the aliens who we contact will be peaceful and benevolent.
I understand that you're thinking of the worst case scenario, but it's foolish to cut ourselves from any chance of caontacting other life in the galaxy because we're afraid of the unknown.
But what about the key thing we want to discover, ie. the composition of the Earth?
The propogation time, if I understand it right, is equal to distance over velocity (Pt = d/v). However, the velocity is dependent on the composition of the Earth, because the velocity of seismic waves differs depending on the materials properties, density, state, etc. So basically, it seems like you need to know the composition of the Earth before you cand find the time. This seems to confirm the idea that earthquakes can't be used to dtermine the composition of the Earth.
Of course, this method could still be used to get a time if you use the model of the Earth that has been created in the past 50 or so years.
Becuase I know that you can determine the distance of the quake (or nuke) by recording the difference between the P and S wave arrival times. (And then using an empirically discovered curve to determine the distance.)
As far a I knew you couldn't determine the precise times.
I mean, I'm as pessimistic as the next guy, but I refuse to think that a civilization powerful enough to send ships to Earth to destroy life isn't going to be that belligerent. The idea of a whole civilization wanting to wipe out another world just because it exists seems farfetched.
How advanced would a civilization have to be to send out signals? A simple array of radio transmitters beaming out a simple message wouldn't be too hard to build.
And a physical object, however small, would take a lot longer than a radio message to reach another star.
I was under the impression (from my university geo course), that to map the inside of the earth using seismic waves, you need to know the exact time and location that a seismic event began at. This would mean only nuclear weapon tests would be useful for seismic studies.
Does anyone know how they've got around this? A link describing the exact provedure for doing this would be sweet too.
The P and S waves from an earthquake can both travel through solid material. The speed varies depending on the nature of the material.
In fact, the S (or Secondary) waves from an earthquake cannot propogate though a liquid, because they are shear waves, and require the material with cohesion between molecules to propogate. The fact that S waves don't pass through liquid is how we determined the upper core is liquid.
Maybe I'm missing something, but it seems like one of the few reasons to buy star would be for the tech support (the other reason would be the extra management features I guess). With support now available for OO, there's even less reason to buy star.
This might be enough to make me go back to OO. I'm using Office at the moment because my university centres its first year Computing-for-Idiots course around Office products, so using OO means extra work figuring out how to do things by yourself.
Indeed. DC++ and reznet is freakin' bliss. Unforunately, everything else about the internet service here sucks. Browsing is slow, file sharing programs are blcoked, so it's tough to get new material for the hub, and all the good newsgroups are missing.
The nagain, I filled a new 120Gig HDD in about a month, so I'm not complaining too loudly.
This may be kind of obvious, but an interesting benefit of the unmanned nature of this project is that the prototypes can be tested in dangerous, risky conditions. (Assuming the prototpyes are cheap or sturdy enough to make it economical.)
So, they won't have to be sure the transition will work before they test it in the real world.
How do you expect advanced space technology to be developed without an active space program? Not even reagarding the inability to test new designs, how motivated would you be to work on ne technology if you were sure it wouldn't be used in your lifetime?
I seem to recall that the military cut off GPS signals in Iraq during the recent war. (For everyone except the military off course.)
It would be interesting to know if they are still denying civilian access to GPS in Iraq.
So I assume the symetrical airfoil would be rather inefficient? If so, would the ineffeciency put a cap on the top speed of a design using the symetrical airfoil?
How are they going to make the airfoil symetrical for fixed-winf flight? Wouldn't one half of the wing be facing in the right direction, and the other half be "backwards"?
It didn't mention this in any of the links as far as I can tell. The only solution I can think of is a symetrical airfoil from front to back.
Something's wrong withthe link.
Why is finding out there's liquid CH4 (that's methane right?) on Titan important? Is it just another piece of data about the solar system?
Slashdot Mirror
Ya, maybe they'll set up a rail gun on the Moon.
Put it on the border between the dark and light sides of the moon. Then, you can point it one way shoot stuff at Mars, and the other way to shoot stuff at Earth.
How exactly does the key work?
This would simply find what time the seismic waves from the quake reached the seismograph station. I'm talking about the time that the actual quake (ie. the snapping of the rock) occured at.
Do you know exactly how they get the time from the empirical graphs? Your explanation makes a fair bit of sense, but as far as I know the graphs of P and S wave can't be used to determine the time.
Who ever said anything about catching up?
Maybe the aliens who we contact will be peaceful and benevolent.
I understand that you're thinking of the worst case scenario, but it's foolish to cut ourselves from any chance of caontacting other life in the galaxy because we're afraid of the unknown.
But what about the key thing we want to discover, ie. the composition of the Earth?
The propogation time, if I understand it right, is equal to distance over velocity (Pt = d/v). However, the velocity is dependent on the composition of the Earth, because the velocity of seismic waves differs depending on the materials properties, density, state, etc. So basically, it seems like you need to know the composition of the Earth before you cand find the time. This seems to confirm the idea that earthquakes can't be used to dtermine the composition of the Earth.
Of course, this method could still be used to get a time if you use the model of the Earth that has been created in the past 50 or so years.
Do you happen to know how they find the time?
Becuase I know that you can determine the distance of the quake (or nuke) by recording the difference between the P and S wave arrival times. (And then using an empirically discovered curve to determine the distance.)
As far a I knew you couldn't determine the precise times.
Why so pessimestic?
I mean, I'm as pessimistic as the next guy, but I refuse to think that a civilization powerful enough to send ships to Earth to destroy life isn't going to be that belligerent. The idea of a whole civilization wanting to wipe out another world just because it exists seems farfetched.
I would think: -Send a deatiled signal towards the star we received the signal from -focus a lot of telescope power on that star
How advanced would a civilization have to be to send out signals? A simple array of radio transmitters beaming out a simple message wouldn't be too hard to build.
And a physical object, however small, would take a lot longer than a radio message to reach another star.
I was under the impression (from my university geo course), that to map the inside of the earth using seismic waves, you need to know the exact time and location that a seismic event began at. This would mean only nuclear weapon tests would be useful for seismic studies.
Does anyone know how they've got around this? A link describing the exact provedure for doing this would be sweet too.
The P and S waves from an earthquake can both travel through solid material. The speed varies depending on the nature of the material.
In fact, the S (or Secondary) waves from an earthquake cannot propogate though a liquid, because they are shear waves, and require the material with cohesion between molecules to propogate. The fact that S waves don't pass through liquid is how we determined the upper core is liquid.
Maybe I'm missing something, but it seems like one of the few reasons to buy star would be for the tech support (the other reason would be the extra management features I guess). With support now available for OO, there's even less reason to buy star.
So what you're saying is, Open Office is finally stepping ito the light?
Not too difficult is sometimes too much work when you're cramming for a midterm the next day.
This might be enough to make me go back to OO. I'm using Office at the moment because my university centres its first year Computing-for-Idiots course around Office products, so using OO means extra work figuring out how to do things by yourself.
Indeed. DC++ and reznet is freakin' bliss. Unforunately, everything else about the internet service here sucks. Browsing is slow, file sharing programs are blcoked, so it's tough to get new material for the hub, and all the good newsgroups are missing. The nagain, I filled a new 120Gig HDD in about a month, so I'm not complaining too loudly.
This may be kind of obvious, but an interesting benefit of the unmanned nature of this project is that the prototypes can be tested in dangerous, risky conditions. (Assuming the prototpyes are cheap or sturdy enough to make it economical.) So, they won't have to be sure the transition will work before they test it in the real world.
How do you expect advanced space technology to be developed without an active space program? Not even reagarding the inability to test new designs, how motivated would you be to work on ne technology if you were sure it wouldn't be used in your lifetime?
I seem to recall that the military cut off GPS signals in Iraq during the recent war. (For everyone except the military off course.) It would be interesting to know if they are still denying civilian access to GPS in Iraq.
So I assume the symetrical airfoil would be rather inefficient? If so, would the ineffeciency put a cap on the top speed of a design using the symetrical airfoil?
How are they going to make the airfoil symetrical for fixed-winf flight? Wouldn't one half of the wing be facing in the right direction, and the other half be "backwards"? It didn't mention this in any of the links as far as I can tell. The only solution I can think of is a symetrical airfoil from front to back.
Something's wrong withthe link. Why is finding out there's liquid CH4 (that's methane right?) on Titan important? Is it just another piece of data about the solar system?