Both of which have GM modifications for sale as we speak.
You are correct, the grandparent was speaking of herbicides while I typed in pesticides but the point is still valid. Both chemicals are needed to acheive good growth and BOTH types of chemicals have been inserted into various GM crops.
I used the wrong word...I admit it....but that mistake actually strengthened my argument by pointing out how GM plants can allow you to lower the use of SEVERAL different types of chemicals.
He was saying he use to use 100 gallons of pesticide A on traditional crops....with GM crops he now only uses 10 gallons of pesticide A.
Now if you go to pesticide B which is 20X stronger you would only be using HALF a gallon instead of 5 gallons....the GM crops still use less pesticide.
As I acknowledged earlier, I am not saying that in theory an entropy stable system is impossible....rather I am saying that there is no possible way to BUILD such a system.
Now of COURSE you cannot define the entropy of an electron. This is again based on the first law of thermodynamics, conservation of energy. A single object isolated from EVERYTHING else will never change.
However put two things in that system...any two things and you can't predict what will happen based on prior knowledge. This is exactly why the 2nd law was created. By it's very deffinition entropy can only effect two or more things.
Now actually, you CAN determine the entropy of an atom or a molecule. These things are created out of subunits which can exist on their own. There are spontaneous nuclear reactions (radio-active materials are obvious but you can also get spontaneous fusion and fission) and a big driving force behind them IS entropy. In my other post today I went through and carefully explained the entropy driving molecules, atomic reactions are similar but you also now have to take into account the entropy of the energy leaving/entering the atom in the form of mass loss and radiation.
Now I will redily admit that we currently cannot directly measure the entropy of a single atom/molecule. We must infer the AVERAGE entropy in a system based on meausrements of a large sample. This however does NOT mean that individual atoms/molecules do not have entropy...it on;y means we can't measure it directly.
Not at all. Absolute reversible processes are certainly allowed...in theory.
As I mentioned we can concive of entropy stable systems however realisticly we can not build them.
I would also like to point out that the example you gave and nanotech absolutly are both non-reversible processes.
A reversible process will spontaneously revert to prior components...a molecule will fall apart...now at the same time thoes components are staying coming together for a net change of zero.
The concentrations of products vs reagents are actually entropy driven...The system will come to equilibrium when the push of entropy (having multiple chemicals floating around) balances any energy released by combining them into a single process.
HOWEVER reversible processes do ZERO work (Conservation of Energy). In order to create your nanites you will have to pour energy into the system to get the balance to favor your devices (same with the tea cup). Once everything is created which is actually a bunch of farily low energy reactions that are easily reversed you then essentially put a lock on it with a high energy reaction.
NOW, since you poured energy into these guys to create them, this energy is stored in the structure in the form of minimized entropy and chemical bonds. However the high energy lock STILL will still maintain a ration of products vs reactants. Once the lock falls off the entier structure will quickly fall apart driven by the entropy release....this is freshman chemistry btw.
The logic behind this is simple....Very complicated structres must be built to exatcing standards. Every piece must be exactly the right size and placed in exactly the right place at exactly the tright time or the whole building falls down.
Chemistry is no different....you start out with say 1000 different chemicals that are used to build these nanites. You start by adding chem A to chem B to get chem AB. To make this reaction go efficiently you will need to adjust the temperature, pressure etc. Now you add chem C to chem AB to get ABC. This requiers different temp and pressures.
Now once it starts falling abart you are unlikly to get the right local temperature/pressure at the same tome as the correct chemicals get close enough. You will end up with a big mix of all the various components of your machines floating about...useless. There will be a few that sponaneously come together but the rate will be so slow as compared to the falling apart as to be non-existant.
This is exactly why the gray goo will never happen. It will take the machines EXACTLY the same amount of energy to build one of itself as it takes us to build one (again conservation of energy) however we can seperate the various components in beakers etc making it easier. Nanites will not have this luxury.
Google has 15,897 more if you like. Every one I reviewed said entropy can ONLY increase.
As per your statement, I beleive I DID refute your claim.
You put forth a tea cup as a model for your claim that entropy remains constant.
I provided two counter examples that directly refute your claim. One immediate and one very long term. Tea evaporating and wood rotting. Both of these will increase the entropy of your system unless energy is used to counter act it.
I also provided an atomic view of the world that directly refutes your claim vis-avis nanotech.
This principle is represented in the "activation energy" of chemical reactions. You can graph it by drawing a line followed by a hump with another line following the hump at a different height than the first.
In a chemical reaction you must put enough energy into the molecules to get them over the hump. The hump represents how dificult it is to get the atoms where they need to be. The height of the lines represents the energy level of the products based on bond energy and entropy level.
Now, please remember that atoms are not all at the same energy level. Temperature only represents the AVERAGE energy level. Now if the hump is close to the line on one side, the chance of a random higher energy molecule hitting your fancy nanite and giving it enough energy to break apart goes up dramatically.
As per YOUR physics knowledge, I will admit there is the possibility of a system which does not spontaneously increase entropy. However this system absolutly requiers a closed system and pre-existing uniform entropy. Your example has neither of these. Now systems like this has ever been observed or created and no one anticipates finding them.
I suggest that you review your physics books and sample problems before you try and design an entropy static system.
#1 a teacup sitting on a table is not in a very high entopy level compared to the requierments of nanotech.
#2 you are assuming the only things in the system are the table, the tea cup and gravity...the reality is that the only closed system is the entier universe. The table will eventually rot dropping the teacup. The tea will evaporate off (increasing entropy) etc.
#3 nanotech is more like the "magic" acts that include someone spinning a saucer on top of a 10 foot pole...in a closed system, with no friction, no air resistance and perfect balance, that is a stable setup. This is not a realistic statment.
#4 At atomic scales all atoms have a "jitter." The are always bouncing around. It takes energy to place them into the correct position and depending on the stability of the bond the random jitters of the neighboring atoms can impart enough energy to break the bond you just established.
#5 Only when everything in the system is at exactly the same entropy level (as in when there is NO free energy in the system) will the entropylevel stay the same. In all other cases it will trend upwards.
Apply this to any situation and you will find that the higher the order in the system the more energy it takes to keep the system in that higher state of order.
Now in normal life this isn't THAT big an issue....but when you are takinging about manipulating single atoms at an angstrom level of accuracy the energy requiered to construct and then maintain it gets to be incredibly.
Wow! I wish I had the free time to proofread the submitions OTHER people made on an INTERNET website...a place were people use leet-speak on a regular basis!
I did not intend to say that the siRNA sequence will no longer become functional, rather the blue rose will not breed true.
Since the original colors genes are still intact AND stil expressed, once the siRNA is removed (say through breeding) the colors will once again appear.
The ONLY way to make this line breed true (and therefore become a strain) is to either knock out the colors or prevent expression....it looks like knocking out the "Rose DFR gene" would do it.
SiRNA is a RNA that is maintained by the host completly seperate from the genome. It happens to compliment the RNA of the target gene and therefore inhibits expression.
SiRNA is not stable long term. THese roses will slowly revert to the original levels of Red/Orange with blue tossed in as well.
To make this permenent you will need to deactivate the color genes on the genome level rather than the cytoplasmic/transcription level.
The number of connections does not represent the ammount of data the neuron has direct access to but rather the level of parralelism in the computation.
The "data" of a neurion is actually stored in the neural junctions. It is stored by modifying the sensitivity to neurotransmitters and whether stimulation by the neurotransmitters means fire the neuron or suppress the firing. This is also where the neuron "processes" information.
While the parrelelism of the brain is unquestioned, the neuronal access to information is limited to a few hundred to a thousand pieces of data.
Now this is already far in excess of silicone but it is no where near "infinite" data access. However at the same time this basic data must then be processed and combined into usefull signals....this is what slows the brain down while at the same time making it an incredibly dynamic yet stable structure.
Now if we were to transalte this into silicone we would essentially give every gate a place to store it's recent states while at the same time giving hundreds to thousands of other gates the ability to directly query the state of that gate X # of cycles ago.
Each neuron really does operate as a mini processor but it doesn't have access to ALL memory. It only has access to a small fraction of it.
So each neuron can simultaneously access one unit of it's own memory...and therefore the brain can access billions of peices of info at a time BUT it still needs to compile the little bits together which slows it down somewhat.
The universities will find it very difficult to add hardware to the probe when it is at the edge of the solar system.
We are not talking about having the universities create and launch a new system...we are talking about essentially a maint. organisation for the last few years of the project.
I think the best way to do it is to have the universities run the program with NASA oversite. This cuts the cost to NASA, provides the universities with a selling point to applicants and direct control over data priorities.
I leave the NASA oversight in so that there is a backup to the university system if something goes wrong.
To be honest this is all ready beyond my math background.
All I can do is point you to the FAQ of a company actually trying to build the thing. I am going to assume they have run the numbers and have been back checked throughly.
http://liftport.com/faq.php#science6a
According to their initital design, they will be be able to launch one 5 ton load per day or one 13 ton load every 3 days.
The design they have will result in a ribbon that weighs 7.5 kg per Kilometer! Plus about the upper 1/3 of the below GEO will reach orbit.
Now to build one that could carry 20 tons/day like you suggested would weigh at least 30 kg/KM and probably a bit more. So even with the larger version you suggested it wouldn't cause much damage and most would get burnt up on the way down.
Now regarding orbit's that dip below LEO, that isn't a problem. As it dips below LEO the object is moving the fastest and the friction with the atmosphere will slow it and therby making theorbit more circular. So long as the object has enough energy to circularize ABOVE LEO it's won't matter if it dips below LEO temporarily.
As for the crashing....you need to remember that as something falls it gains energy.
So while the section of ribbon 5 KM below the Geosync spot will not have enough speed to maintain THAT orbit, as it falls it will aquier energy and thus be able to enter a lower orbit.
Now this new orbit will be very elliptical and the ellipse will become more extreme as you get closer to the surface. But, so long as the elipse doews not brush the atmosphere it will be stable.
Now if the cable stayed in one piece even the top sections that COULD enter stable orbits would get dragged down with the rest. However this will slow the overall desent of the cable and probably minimizing damage.
Below LEO the sections of cable will not be able to escape the atmosphere and would thus crash.
Plus even if the cables turn out not to be strong enough to support a geosync-surface elevator we could still build a much less ambitious high atmosphere-geosync or slightly lower elevator.
You fly a plane up to a platform and take the cable up the rest of the way. Bu cutting off the bottom 10 KM you reduce the overall tension and atmosphere effects. The downside is that you have to use fuel to get up to the platform and it may not be geosync-and therefore geographically stable.
Plus the technology that is needed for a space elevator has innumerable uses here on earth or in current space tech.
Using nanotubes you could build a suspension bridge over the straigh of jibralta (sp?) in europe. You could disign vehicle cabs that are essentially impervious at current speeds for a fraction of the weight...etc.
Actually even the best steel we have could not even in theory support it's own weight let alone a payload if set up as a cable.
A GROUND to Geosync cable HAS to be nano tubes.
You can make a Low Earth Orbit (LEO) tether out of current materials like kevlar etc. So you fly up to the stationary platform just above the atmosphere and ride the cable up to Geosync.
As for a cable crashing, it is important to remember that just because part of it is below geosync orbit, it doesn't mean that it will crash on the planet. Actually pretty much anything above LEO will go into orbit and not hit the surface. Below LEO it will be slowed by the atmosphere and therfore deorbit and crash....not technically this COULD bring the hole bottom half down but the reality is that somewhere along the cable it will burn through as the lower parts enter the atmosphere allowing the upper sections to maintain an orbit. Not to mention that we could sever the cable with a missle etc or even build in a cutting mechanism to sever the cable in that event.
As for heat of reentry...right now the space shuttle flys in LEO. It requiers special shielding and temperatures can STILL get up to several thousand degrees as it re-enters. At geosync orbit things are moving at roughly 24,000 MPH....lower down they have to move even faster....plenty of energy to burn things up.
While the original concept of a space elevator was a cable, newer models are actually ribbons with a very slight curve. This design does not sacrifice any strength but does lower the risk of being hit by a meteor (don't as me how I haven't seen the math) AND increases wind resistance as it falls. This increased wind resistance will increase the heat generated by the atmosphere burning up even more cable as well as slow the overall desent to that of a piece of paper dropped off a building. PLUS your 50 KM of cable will be stretched out over 50 KM not piled onto one place which will minimize the damage.
As for your catapult idea you need to remember that ALL satelites have to have mechanisms to control their orbit. All sattelites need to beable to track a traget, fine tune it's position and compensate for any drag that if might get from stray molecules.
It's only the true cargo...the stuff that is being built into something else that needs to be caught...and you already have to have vehicles up there to build the things:-)
I do like the floating Cargo launcher idea....it will have to be friggin HUGE to be able to support the launcher and cargo....so why not cover the exterier with solar cells....that should give you enough power to launch some of your cargo for free:-)
Actually simple nanotubes would do the trick...but we still need to manufacture them:-) Plus once we get better at making them we can find stronger variants...double-walled etc.
We already commonly manufacture wires or threads that are 100's of Km long.
You are correct that the cable will probably be anchored and under extra tension so it can carry a little extra weight.
The advantage of space elevators/cables is that they are self correcting. You DON'T have to expend much delta-V to keep it stable even during construction.
As for the Day Might cycle you forget that the vast magority of the cable will be outsid earth's umbra. It will be in daylight ALL the time. The part that WILL have a day night cycle will mainly be in the atmosphere which will prevent massive heat changes and therefore prevent massive size changes...Plus Nanotubes already stretch length wise (this will be taken account in the construction) and almost all the thermal expansion is in the horizantal plane.
As for snapping...There is a chance of it getting hit by something large enough to destroy the cable....however even the smallest cable (the one currently being planned) can withstand hits my 5 cm debris and possibly up to 10 cm. We already track everything 10 CM or bigger and they plan on getting that down to 1 CM. Then you activly move the cable to dodge the debris. The current concept has the cable attached to a ship which moves a few KM a day to avoid debris.
Finally, should it get hit and fall down you are correct that anything above the Geosync level will fly off and anything below it (about 1/3 of it) will fall down. But it is important to remember that while the whole thing will be VERY heavy the actual density will be pretty low. Plus it is made of what is essentially graphite. The vast magority will burn up in the atmosphere on the way down. What remains will have roughly the consistency of paper.
But I have to say I had never heard of the Lighter than air catapult....interesting idea. You won't even really need something to catch it. You can vary the angle and initial velocity to make the payload orbit with minimal thrust from the payload.
Personally I think a mix of these technologies will be the final solution.
The elevator will only be attached in the most rudimentary form of the word. It will probably be clamped so we can dampen any vibrations that it develops but that would not effect it's strength. A space elevator can be perfectly functional floating 5 inches above the ground.
The rules of orbital dynamics are actually determined by gravity, velocity, angular velocity and acceleration. Centripetal force is a combination of velocity, acceleration and angular velocity.
As you can see orbital dynamics is just a specific application of centripital force using gravity as the acceleration source.
It is best to think of orbital dynamics as a spinning invisible string. In a two body system (the only trully stable orbit) both items lie somewhere in the middle of that invisible string (Not at the ends). Orbital dynamics allows you to predict what the objects will do when you tap them.
You are confusing the idea of a ribbon with a spinning string.
If you spun a string so that the center of the circle it creates is INSIDE the string you are correct in stating that the string will remain taught so long as both sides have the same inertia. If the center of rotation is outside the sting than the string will get flung out. The experiment is to take a record player (Old I know) and put your string one one side of the center. When you spin up the record the string will go flying.
For your model to maintain tension it would have to spin end to end. There are actually models like that already in existence but they are NOT space elevators as everyone knows them.
Now for the Space elevator. I would like to point out that we could put geosync space elevators on other planets....even planets like venus which has a single rotation per year. Based on your model it would be impossible to create such things as geosync because the centripital force created will be very different. PLUS assuming that earth just HAPPENED to have the correct spin to get a geosyn cable due to centripital forces caused by it's rotation (it doesn't) the cable itself will weigh gigatons under great force. You would have to somehow hold that weight down which honestly would be harder than creating the cable. In addition the tension would snap the cable because the bottom would have to support double the whole weight of the cable....the cable plus an equal amount of earths mass.
Finally, how would you build such a system? The only way would be to build the cable on the ground then attach massive rockets (with more delta-v than mankind has every used in it's existence) and drag it up.
So your concept of a cable is technically possible but absolutely impossible to build.
Now imagine mine....you put up a satellite into geosync orbit. It now starts to extrude cable down to the earth and up into space. The whole mass is STILL moving at geosync orbit...The cable that is closer to earth will now be moving too slow for it's orbit and will begin to fall to earth. The cable going into space will now be travelling too fast for it's orbit and will try to fall off into space....the net effect is the cable is held tight up and down with the maximum tension being one cables weight at geosync orbit.
Now it isn't that straight forward...the cable fed downwards will have a greater effect on the system than the cable feed upwards due to gravity stronger effect therefore if you wanted to use a simple cable for the system it will have to reach about 1/3 of the way to the moon. This is why the topside has a counter wieght....just to cut down on it's length.
Plus in a space cable system the ground side will have no tension and all the tension will be in the center of mass...therefore most space cable designs are actually much thincker in the middle. this allows it to hold a lot more weight. But it does complicate the orbit.
While a small part of the tension DOES come from the rotation of the cable it is actually contrary t
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Both of which have GM modifications for sale as we speak.
You are correct, the grandparent was speaking of herbicides while I typed in pesticides but the point is still valid. Both chemicals are needed to acheive good growth and BOTH types of chemicals have been inserted into various GM crops.
I used the wrong word...I admit it....but that mistake actually strengthened my argument by pointing out how GM plants can allow you to lower the use of SEVERAL different types of chemicals.
you seem to have missed his point.
He was saying he use to use 100 gallons of pesticide A on traditional crops....with GM crops he now only uses 10 gallons of pesticide A.
Now if you go to pesticide B which is 20X stronger you would only be using HALF a gallon instead of 5 gallons....the GM crops still use less pesticide.
Also, sorry about the spelling errors....it is early in the morning here :-)
As I acknowledged earlier, I am not saying that in theory an entropy stable system is impossible....rather I am saying that there is no possible way to BUILD such a system.
Now of COURSE you cannot define the entropy of an electron. This is again based on the first law of thermodynamics, conservation of energy. A single object isolated from EVERYTHING else will never change.
However put two things in that system...any two things and you can't predict what will happen based on prior knowledge. This is exactly why the 2nd law was created. By it's very deffinition entropy can only effect two or more things.
Now actually, you CAN determine the entropy of an atom or a molecule. These things are created out of subunits which can exist on their own. There are spontaneous nuclear reactions (radio-active materials are obvious but you can also get spontaneous fusion and fission) and a big driving force behind them IS entropy. In my other post today I went through and carefully explained the entropy driving molecules, atomic reactions are similar but you also now have to take into account the entropy of the energy leaving/entering the atom in the form of mass loss and radiation.
Now I will redily admit that we currently cannot directly measure the entropy of a single atom/molecule. We must infer the AVERAGE entropy in a system based on meausrements of a large sample. This however does NOT mean that individual atoms/molecules do not have entropy...it on;y means we can't measure it directly.
Not at all. Absolute reversible processes are certainly allowed...in theory.
As I mentioned we can concive of entropy stable systems however realisticly we can not build them.
I would also like to point out that the example you gave and nanotech absolutly are both non-reversible processes.
A reversible process will spontaneously revert to prior components...a molecule will fall apart...now at the same time thoes components are staying coming together for a net change of zero.
The concentrations of products vs reagents are actually entropy driven...The system will come to equilibrium when the push of entropy (having multiple chemicals floating around) balances any energy released by combining them into a single process.
HOWEVER reversible processes do ZERO work (Conservation of Energy). In order to create your nanites you will have to pour energy into the system to get the balance to favor your devices (same with the tea cup). Once everything is created which is actually a bunch of farily low energy reactions that are easily reversed you then essentially put a lock on it with a high energy reaction.
NOW, since you poured energy into these guys to create them, this energy is stored in the structure in the form of minimized entropy and chemical bonds. However the high energy lock STILL will still maintain a ration of products vs reactants. Once the lock falls off the entier structure will quickly fall apart driven by the entropy release....this is freshman chemistry btw.
The logic behind this is simple....Very complicated structres must be built to exatcing standards. Every piece must be exactly the right size and placed in exactly the right place at exactly the tright time or the whole building falls down.
Chemistry is no different....you start out with say 1000 different chemicals that are used to build these nanites. You start by adding chem A to chem B to get chem AB. To make this reaction go efficiently you will need to adjust the temperature, pressure etc. Now you add chem C to chem AB to get ABC. This requiers different temp and pressures.
Now once it starts falling abart you are unlikly to get the right local temperature/pressure at the same tome as the correct chemicals get close enough. You will end up with a big mix of all the various components of your machines floating about...useless. There will be a few that sponaneously come together but the rate will be so slow as compared to the falling apart as to be non-existant.
This is exactly why the gray goo will never happen. It will take the machines EXACTLY the same amount of energy to build one of itself as it takes us to build one (again conservation of energy) however we can seperate the various components in beakers etc making it easier. Nanites will not have this luxury.
This is of course why we don't have them now...
I would quote my physics books but it is harder to provide a link to a hardback book ;-)
d ynamics.html i stry/Miscellenous/Helpfile/spontaneityentropy/2ndl aw.htm
but here are a few more links:
http://theory.uwinnipeg.ca/mod_tech/node78.html
http://www.christiananswers.net/q-eden/edn-thermo
http://www.cartage.org.lb/en/themes/Sciences/Chem
Google has 15,897 more if you like. Every one I reviewed said entropy can ONLY increase.
As per your statement, I beleive I DID refute your claim.
You put forth a tea cup as a model for your claim that entropy remains constant.
I provided two counter examples that directly refute your claim. One immediate and one very long term. Tea evaporating and wood rotting. Both of these will increase the entropy of your system unless energy is used to counter act it.
I also provided an atomic view of the world that directly refutes your claim vis-avis nanotech.
This principle is represented in the "activation energy" of chemical reactions. You can graph it by drawing a line followed by a hump with another line following the hump at a different height than the first.
In a chemical reaction you must put enough energy into the molecules to get them over the hump. The hump represents how dificult it is to get the atoms where they need to be. The height of the lines represents the energy level of the products based on bond energy and entropy level.
Now, please remember that atoms are not all at the same energy level. Temperature only represents the AVERAGE energy level. Now if the hump is close to the line on one side, the chance of a random higher energy molecule hitting your fancy nanite and giving it enough energy to break apart goes up dramatically.
As per YOUR physics knowledge, I will admit there is the possibility of a system which does not spontaneously increase entropy. However this system absolutly requiers a closed system and pre-existing uniform entropy. Your example has neither of these. Now systems like this has ever been observed or created and no one anticipates finding them.
I suggest that you review your physics books and sample problems before you try and design an entropy static system.
Please refer to the wikipedia refference to thermodynamics:
d _Law_of_Thermodynamics
http://www.nwcreation.net/wiki/index.php?title=2n
#1 a teacup sitting on a table is not in a very high entopy level compared to the requierments of nanotech.
#2 you are assuming the only things in the system are the table, the tea cup and gravity...the reality is that the only closed system is the entier universe. The table will eventually rot dropping the teacup. The tea will evaporate off (increasing entropy) etc.
#3 nanotech is more like the "magic" acts that include someone spinning a saucer on top of a 10 foot pole...in a closed system, with no friction, no air resistance and perfect balance, that is a stable setup. This is not a realistic statment.
#4 At atomic scales all atoms have a "jitter." The are always bouncing around. It takes energy to place them into the correct position and depending on the stability of the bond the random jitters of the neighboring atoms can impart enough energy to break the bond you just established.
#5 Only when everything in the system is at exactly the same entropy level (as in when there is NO free energy in the system) will the entropylevel stay the same. In all other cases it will trend upwards.
2nd law of thermodynamics.
"entropy is always increasing"
Apply this to any situation and you will find that the higher the order in the system the more energy it takes to keep the system in that higher state of order.
Now in normal life this isn't THAT big an issue....but when you are takinging about manipulating single atoms at an angstrom level of accuracy the energy requiered to construct and then maintain it gets to be incredibly.
Perhaps you should work on having original thoughts rather than proofreading someone elses.
People seem to think that nanotech is magic.
It really isn't, it obeys the same laws as the rest of the universe. A big law being THERMODYNAMICS.
One aspect of the peky little law is that the tighter you try and control something the more energy it takes.
Nanotech is based on controling the EXACT 3 demensional placement of atoms....about as highly controled as you can get.
Nanotech is going to requier HUGE amounts of energy....
No translate that to the real world...a Nanite is kept in a container specially designed to supply the energy for it to function.
It gets out and discovers that there is not enough free energy around to build additional nanites faster than they are destroyed by nature.
Nanites will be very usefull for very specific reactions but the assembilers will be almost useless outside of a controled environment.
Wow! I wish I had the free time to proofread the submitions OTHER people made on an INTERNET website...a place were people use leet-speak on a regular basis!
siRNA is straight forward competitive inhibition.
It works because it is cheap and fast to do.
I did not intend to say that the siRNA sequence will no longer become functional, rather the blue rose will not breed true.
Since the original colors genes are still intact AND stil expressed, once the siRNA is removed (say through breeding) the colors will once again appear.
The ONLY way to make this line breed true (and therefore become a strain) is to either knock out the colors or prevent expression....it looks like knocking out the "Rose DFR gene" would do it.
it was a pleasure :-)
They use siRNA to turn off the color genes.
SiRNA is a RNA that is maintained by the host completly seperate from the genome. It happens to compliment the RNA of the target gene and therefore inhibits expression.
SiRNA is not stable long term. THese roses will slowly revert to the original levels of Red/Orange with blue tossed in as well.
To make this permenent you will need to deactivate the color genes on the genome level rather than the cytoplasmic/transcription level.
The number of connections does not represent the ammount of data the neuron has direct access to but rather the level of parralelism in the computation.
The "data" of a neurion is actually stored in the neural junctions. It is stored by modifying the sensitivity to neurotransmitters and whether stimulation by the neurotransmitters means fire the neuron or suppress the firing. This is also where the neuron "processes" information.
While the parrelelism of the brain is unquestioned, the neuronal access to information is limited to a few hundred to a thousand pieces of data.
Now this is already far in excess of silicone but it is no where near "infinite" data access. However at the same time this basic data must then be processed and combined into usefull signals....this is what slows the brain down while at the same time making it an incredibly dynamic yet stable structure.
Now if we were to transalte this into silicone we would essentially give every gate a place to store it's recent states while at the same time giving hundreds to thousands of other gates the ability to directly query the state of that gate X # of cycles ago.
Close but not perfect.
Each neuron really does operate as a mini processor but it doesn't have access to ALL memory. It only has access to a small fraction of it.
So each neuron can simultaneously access one unit of it's own memory...and therefore the brain can access billions of peices of info at a time BUT it still needs to compile the little bits together which slows it down somewhat.
Every system has it's tradoffs.
Hold on there cowboy!
The universities don't need a launch vehicle.
The universities will find it very difficult to add hardware to the probe when it is at the edge of the solar system.
We are not talking about having the universities create and launch a new system...we are talking about essentially a maint. organisation for the last few years of the project.
I think the best way to do it is to have the universities run the program with NASA oversite. This cuts the cost to NASA, provides the universities with a selling point to applicants and direct control over data priorities.
I leave the NASA oversight in so that there is a backup to the university system if something goes wrong.
Actually the stock sale is not at all unusual.
Selling on a limited basis means big investors...100K minimum.
I agree the 7.5 is probably an average over the whole things and the bottom section will probably be significantly less.
To be honest this is all ready beyond my math background.
All I can do is point you to the FAQ of a company actually trying to build the thing. I am going to assume they have run the numbers and have been back checked throughly.
http://liftport.com/faq.php#science6a
According to their initital design, they will be be able to launch one 5 ton load per day or one 13 ton load every 3 days.
The design they have will result in a ribbon that weighs 7.5 kg per Kilometer! Plus about the upper 1/3 of the below GEO will reach orbit.
Now to build one that could carry 20 tons/day like you suggested would weigh at least 30 kg/KM and probably a bit more. So even with the larger version you suggested it wouldn't cause much damage and most would get burnt up on the way down.
Now regarding orbit's that dip below LEO, that isn't a problem. As it dips below LEO the object is moving the fastest and the friction with the atmosphere will slow it and therby making theorbit more circular. So long as the object has enough energy to circularize ABOVE LEO it's won't matter if it dips below LEO temporarily.
As for the crashing....you need to remember that as something falls it gains energy.
So while the section of ribbon 5 KM below the Geosync spot will not have enough speed to maintain THAT orbit, as it falls it will aquier energy and thus be able to enter a lower orbit.
Now this new orbit will be very elliptical and the ellipse will become more extreme as you get closer to the surface. But, so long as the elipse doews not brush the atmosphere it will be stable.
Now if the cable stayed in one piece even the top sections that COULD enter stable orbits would get dragged down with the rest. However this will slow the overall desent of the cable and probably minimizing damage.
Below LEO the sections of cable will not be able to escape the atmosphere and would thus crash.
Plus even if the cables turn out not to be strong enough to support a geosync-surface elevator we could still build a much less ambitious high atmosphere-geosync or slightly lower elevator.
You fly a plane up to a platform and take the cable up the rest of the way. Bu cutting off the bottom 10 KM you reduce the overall tension and atmosphere effects. The downside is that you have to use fuel to get up to the platform and it may not be geosync-and therefore geographically stable.
Plus the technology that is needed for a space elevator has innumerable uses here on earth or in current space tech.
Using nanotubes you could build a suspension bridge over the straigh of jibralta (sp?) in europe. You could disign vehicle cabs that are essentially impervious at current speeds for a fraction of the weight...etc.
Actually even the best steel we have could not even in theory support it's own weight let alone a payload if set up as a cable.
:-)
:-)
A GROUND to Geosync cable HAS to be nano tubes.
You can make a Low Earth Orbit (LEO) tether out of current materials like kevlar etc. So you fly up to the stationary platform just above the atmosphere and ride the cable up to Geosync.
As for a cable crashing, it is important to remember that just because part of it is below geosync orbit, it doesn't mean that it will crash on the planet. Actually pretty much anything above LEO will go into orbit and not hit the surface. Below LEO it will be slowed by the atmosphere and therfore deorbit and crash....not technically this COULD bring the hole bottom half down but the reality is that somewhere along the cable it will burn through as the lower parts enter the atmosphere allowing the upper sections to maintain an orbit. Not to mention that we could sever the cable with a missle etc or even build in a cutting mechanism to sever the cable in that event.
As for heat of reentry...right now the space shuttle flys in LEO. It requiers special shielding and temperatures can STILL get up to several thousand degrees as it re-enters. At geosync orbit things are moving at roughly 24,000 MPH....lower down they have to move even faster....plenty of energy to burn things up.
While the original concept of a space elevator was a cable, newer models are actually ribbons with a very slight curve. This design does not sacrifice any strength but does lower the risk of being hit by a meteor (don't as me how I haven't seen the math) AND increases wind resistance as it falls. This increased wind resistance will increase the heat generated by the atmosphere burning up even more cable as well as slow the overall desent to that of a piece of paper dropped off a building. PLUS your 50 KM of cable will be stretched out over 50 KM not piled onto one place which will minimize the damage.
As for your catapult idea you need to remember that ALL satelites have to have mechanisms to control their orbit. All sattelites need to beable to track a traget, fine tune it's position and compensate for any drag that if might get from stray molecules.
It's only the true cargo...the stuff that is being built into something else that needs to be caught...and you already have to have vehicles up there to build the things
I do like the floating Cargo launcher idea....it will have to be friggin HUGE to be able to support the launcher and cargo....so why not cover the exterier with solar cells....that should give you enough power to launch some of your cargo for free
It's stationary with respect to earth's magnetic field.
:-(
No current will be created that way
Actually simple nanotubes would do the trick...but we still need to manufacture them :-) Plus once we get better at making them we can find stronger variants...double-walled etc.
We already commonly manufacture wires or threads that are 100's of Km long.
You are correct that the cable will probably be anchored and under extra tension so it can carry a little extra weight.
The advantage of space elevators/cables is that they are self correcting. You DON'T have to expend much delta-V to keep it stable even during construction.
As for the Day Might cycle you forget that the vast magority of the cable will be outsid earth's umbra. It will be in daylight ALL the time. The part that WILL have a day night cycle will mainly be in the atmosphere which will prevent massive heat changes and therefore prevent massive size changes...Plus Nanotubes already stretch length wise (this will be taken account in the construction) and almost all the thermal expansion is in the horizantal plane.
As for snapping...There is a chance of it getting hit by something large enough to destroy the cable....however even the smallest cable (the one currently being planned) can withstand hits my 5 cm debris and possibly up to 10 cm. We already track everything 10 CM or bigger and they plan on getting that down to 1 CM. Then you activly move the cable to dodge the debris. The current concept has the cable attached to a ship which moves a few KM a day to avoid debris.
Finally, should it get hit and fall down you are correct that anything above the Geosync level will fly off and anything below it (about 1/3 of it) will fall down. But it is important to remember that while the whole thing will be VERY heavy the actual density will be pretty low. Plus it is made of what is essentially graphite. The vast magority will burn up in the atmosphere on the way down. What remains will have roughly the consistency of paper.
But I have to say I had never heard of the Lighter than air catapult....interesting idea. You won't even really need something to catch it. You can vary the angle and initial velocity to make the payload orbit with minimal thrust from the payload.
Personally I think a mix of these technologies will be the final solution.
Space elevators ARE free floating constructions.
The elevator will only be attached in the most rudimentary form of the word. It will probably be clamped so we can dampen any vibrations that it develops but that would not effect it's strength. A space elevator can be perfectly functional floating 5 inches above the ground.
The rules of orbital dynamics are actually determined by gravity, velocity, angular velocity and acceleration. Centripetal force is a combination of velocity, acceleration and angular velocity.
As you can see orbital dynamics is just a specific application of centripital force using gravity as the acceleration source.
It is best to think of orbital dynamics as a spinning invisible string. In a two body system (the only trully stable orbit) both items lie somewhere in the middle of that invisible string (Not at the ends). Orbital dynamics allows you to predict what the objects will do when you tap them.
You are confusing the idea of a ribbon with a spinning string.
If you spun a string so that the center of the circle it creates is INSIDE the string you are correct in stating that the string will remain taught so long as both sides have the same inertia. If the center of rotation is outside the sting than the string will get flung out. The experiment is to take a record player (Old I know) and put your string one one side of the center. When you spin up the record the string will go flying.
For your model to maintain tension it would have to spin end to end. There are actually models like that already in existence but they are NOT space elevators as everyone knows them.
Now for the Space elevator. I would like to point out that we could put geosync space elevators on other planets....even planets like venus which has a single rotation per year. Based on your model it would be impossible to create such things as geosync because the centripital force created will be very different. PLUS assuming that earth just HAPPENED to have the correct spin to get a geosyn cable due to centripital forces caused by it's rotation (it doesn't) the cable itself will weigh gigatons under great force. You would have to somehow hold that weight down which honestly would be harder than creating the cable. In addition the tension would snap the cable because the bottom would have to support double the whole weight of the cable....the cable plus an equal amount of earths mass.
Finally, how would you build such a system? The only way would be to build the cable on the ground then attach massive rockets (with more delta-v than mankind has every used in it's existence) and drag it up.
So your concept of a cable is technically possible but absolutely impossible to build.
Now imagine mine....you put up a satellite into geosync orbit. It now starts to extrude cable down to the earth and up into space. The whole mass is STILL moving at geosync orbit...The cable that is closer to earth will now be moving too slow for it's orbit and will begin to fall to earth. The cable going into space will now be travelling too fast for it's orbit and will try to fall off into space....the net effect is the cable is held tight up and down with the maximum tension being one cables weight at geosync orbit.
Now it isn't that straight forward...the cable fed downwards will have a greater effect on the system than the cable feed upwards due to gravity stronger effect therefore if you wanted to use a simple cable for the system it will have to reach about 1/3 of the way to the moon. This is why the topside has a counter wieght....just to cut down on it's length.
Plus in a space cable system the ground side will have no tension and all the tension will be in the center of mass...therefore most space cable designs are actually much thincker in the middle. this allows it to hold a lot more weight. But it does complicate the orbit.
While a small part of the tension DOES come from the rotation of the cable it is actually contrary t