Besides the fact that most traits are caused not by one gene, but by the interaction of dozens of genes and the proteins they create, you have to consider that almost all human traits develop in accordance to someone's environment.
This has been the traditional view, that environment and parenting determine the outcome of one's upbringing. However twins' studies have been turning up some amazing evidence to the contrary.
In some cases of identical twins who were brought up in completely separate households, the twins have met again as adults and discovered incredible similarities in their lives.
Yeah looks like it. ADD SOMETHING INTELLIGENT ^H^H^H^H blib ...
Damn the lameness filter! It wouldn't let me post this comment because it had too many allcaps. Maybe this rant at the end will get it through...despite making my posting even more lame.
I couldn't agree less with your claim that preservation of wildlife is more important than human lives. One of the main reasons sub-Saharan Africa is so poor is because of problems like the tsetse fly. The article points out that they cost the region about $4.5 billion a year and these are people who can't afford that kind of loss.
If science and technology can succeed in hauling these countries into the 21st century you will see the same kinds of voluntary population control that you see in Europe, for example. Many wealthy European countries have a declining native population and it is directly related to economic wellbeing.
The suggestion that the tsetse fly, HIV, etc are helping to deal with population problems in Africa is abhorrent. We need to help solve these problems and make Africa wealthy - then the population problem will solve itself and there will be room for wildlife as well.
Nah those are with huge lasers for open-air displays. All you would need is a good laser pointer. The page you want is here where they have a bunch of cheap components like mirrors and "General scanning 124 Galvo" for a couple hundred.
Also they have a "hackers special" which includes the laser and stuff for $2700, which is almost getting down to the price-range. It looks like the galvo (motors) + mirror subsystem goes for around $1000 though - still pricey.
Nice idea, but tracking the ball movements is not going to be feasible unless you have a very fancy high-speed high-bandwidth camera and a lot of computing power to process images many times a second. The problem is mostly with the break, I should think. The balls are moving essentially at random all over the place in just a fraction of a second. The ball tracker would also have to understand the basic physics of the game, because otherwise even two balls colliding head on would present a big problem. The moving ball may appear to pass through a stationary ball for example.
But all is not lost. I don't see why you can't just track the balls on colour. In pool, each ball has a unique colour and at least some of it is always visible - even on the "stripes" balls (aka bigs or halves). Since you're not tracking movement, you can do all the image processing between shots, taking several seconds if necessary.
Finally, may I suggest, instead of an expensive projector, you could rig up a laser pointer reflected off some kind of servoed mirror. If your computer could manipulate the mirror accurately and quickly enough it could draw out the line along which you should hit. You may well be able to buy these mirror components as they are already used in laser displays for rock bands, museums, etc.
It's like the classic story of the US space-biro and the Russian lead pencils.
The US decided to use an optical mouse for the pointing device on the Hubble, but the Russian designed Hubbliski which never got off the ground due to lack of funding simply used a brown stick.
Can I just go ahead and point out the obvious here. Self-shredding email or whatever you want to call it can only work with the consent of the recipient, which goes completely against the tone of the CNN article:
Senders can destroy messages either remotely or automatically, without a recipient's consent or cooperation.
Just like the whole digital-rights management problem, eventually you have to give access to the message to your recipient and they can store a copy. If it's displayed on your screen then even the most recalcitrant software can be bypassed with a screen-shot or at absolute worst, a photograph of your monitor.
All these schemes can do is make it less convenient to store the email you receive. Even so, the receiving software could be dissasembled (DeCSS style) and you could create tools that would store the plain-text like a normal email client.
For the moralist out there, I wish to ask them one simple question: If we are to be continually called to be the world's cop, like we were in Bosnia, Kosovo, and Somalia, why are you against giving the guys who are doing the dirty work the support to do their jobs? If you don't want us to be the world's cop, then do you have any right to be self rightous about the massacres in these same countries?
Please, do you really think America acts the world-cop because they are called to do so? Do you think they spend billions of dollars out of altruism? Wake up, you have had your own flag pulled over your eyes. The US acts out of self-interest when it comes to military intervention. The benifits are:
o Global stability (don't want any more global conflicts to flare up from seemingly inocuous local wars).
o Weapons development (there's no better field test than taking your new toys into the field and trying them out for real - war games are almost as expensive and not as effective). Weapons development is funded as a means of defending the homeland - so why do you think they are used overseas all the time?
And finally, if you think these kind of actions are just about the US, you're wrong. Europe, Australia and New Zealand are just as capable of dealing with them (yes, Australian special forces are putting there lives on the line in Afghanistan as we speak). They just don't go in as big when the US is already willing to do so. There are plenty of exceptions. The US was uninterested in the civil war in East Timor, so it's fallen to Australia to deal with it.
There's nothing new in a government monitoring such phone calls. Hasn't anyone heard of Echelon or Carnivore?
I'm not saying it's a good thing, but we can pretty much assume that it goes on all the time if you don't use strong encryption for your communications. The only thing unusual about Australia in this regard is firstly that this sort of intelligence gets mentioned publicly and secondly we Australians are very good at whipping up one-sided outrage in the national media.
In the same vein, Slashdot has a nasty tendency to go with the "Australians do it again" angle every time that nation is mentioned. "Australia" translates directly to "privacy issue" in the lexicon of Slashdot-level understanding.
I'm sure this is also a good thing for getting more haptics rendering (ie. force feedback rendering, for example) working on linux.
The challenge with haptics is getting at least a 1kHz frame-rate on force renderings. This requires soft-realtime perfomance at a minimum and is tricky on most platforms.
The writing standards in this review by Richard Menta are amongst the worst I have seen. He repeats almost every piece of information at least once (so you say it supports MP3 and WMA?) and fails to mention some pretty crucial features of any mp3 player. For example, he mentions the lithium-ion batteries "had no trouble handling the power hungry Microdives" - but how long did they actually last?!
Also, testing the VoiceNav feature with 14 songs is laughable. You basically had to know the full artist+track name anyway, so why not just memorise the 14 tracks and refer to them by number? My mp3 player has over 3000 tracks at the moment and I have no confidence that VoiceNav could handle them, despite reading this review which gave it 4 stars. And seriously, on a crowded and noisy subway train who is going to yell "Achey breaky heart" into their shirt pocket?
How can something be both increasingly commercial and subterranean at the same time?
One pointless generalisation that we can make is that people less and less feel the need to pontificate on the direction of the 'net and are less entertained by Wired magazine "gurus" that do so.
"There is no way hydrogen is ever going to be allowed aboard an airplane," Stefener said.
I think this is an overly dismissive statement. Methanol itself is really just a hydrogen storage method. You throw in some carbon to stabilise the hydrogen and as a result, you produce carbon dioxide when the fuel is used up.
There's a lot of work going on to find non-chemical storage methods for hydrogen, such as sponges or matrices that would be explosion-proof. There's no reason to believe that this won't eventually succeed in a safer and more efficient fiel cell than methanol based ones. It will just take longer.
All of these traditional methods are being enhanced by ZeoSync through collaboration with top experts from Harvard University, MIT, University of California at Berkley, Stanford University, University of Florida, University of Michigan, Florida Atlantic University, Warsaw Polytechnic, Moscow State University and Nankin and Peking Universities in China, Johannes Kepler University in Lintz Austria, and the University of Arkansas, among others.
The claims about their compression performance are clearly false - but even legitimate companies are known to exaggerate and oversell. However this list of academic collaborators is the most damning evidence of a hoax, IMHO. Having worked on quite a few projects at the interface of commercialisation and academia, I can promise you that there is no way any project can run with such a long list of partners. Maybe 2 or 3 would be beleivable.
Maybe Apple is letting them start the buzz a little early.
No I don't buy that at all. Jobs is a showman. Apple got real pissed when previous products were leaked just prior to MacWorld. It's a major embarassment - no question.
Traditional rockets tend to burn up to one quarter of their overall fuel reserves before they lift the first inches off the ground/out the silo.
What do you mean the first inches? For industrial rockets there's no way they burn a quarter of their fuel in a few inches. Maybe if you phrase it as "before they travel their own length off the pad"?
I agree generally with what you're saying. It's interesting that this discussion doesn't seem to have come up much in Edwards' report. One thing he advocates is using a floating platform like the Boeing SeaLaunch. This would allow you to move the cable out of the way of space debris on an hourly basis and away from storm systems. However the angulam momentum issue would cause an overall westward pull. The total impulse involved would be comparable to the impulse applied to the cargoes (ie. they're heavy payloads being given planetary transfer velocities), so the platform would need to be pushing east all the time in order to maintain position.
Just to summarise how I understand the angular momentum issue now: When a payload is launched its angular momentum is increased by, say, A. This is taken from the cable, causing it to lean west slightly. As it leans west it will transfer its angular momentum to the Earth via both the coupling with the ground/sea and via a correcting gravitational torque (which of course acts equally and oppositely on the cable and the Earth). The cable will then pendulate east and west, transferring angular momentum back and forth between itself and the Earth. If left in this state I suppose the oscillation would eventually dampen out from friction with the atmosphere and from induced currents in the cable as it moves through the Earth's magnetic field. This may well take millions of years though. If you then time a subsequent launch (when the cable is swinging east, say) then you can stop it in the vertical position, cancelling the oscillation. At this point the cable will have transferred 2A units of westward angular momentum to the Earth.
It may well be however that these issues are not a consideration for designers. If the induced oscillation is small enough then you could simply launch whenever you like and you would be increasing the oscillation about half the time and decreasing it the other half of the time. Overall it would be very unlikely that a problem would develop.
Yes that's what I'm saying. You take a Neo, remove the expensive bits and add an ethernet chip. I'm not saying anyone would want to do this, I'm just comparing the components you have in the different products.
Yes, finally nested 6 or 7 deep the correct and simple answer to the question. The angular momentum comes from the Earth.
As a payload climbs the cable its angular momentum is increasing. This is initially transferred to the cable which may or may not pendulate. However since the cable is pulling upwards under centripetal acceleration, it will eventually transfer its extra angular momentum to the Earth.
I don't agree however that you could cancel the effect out by timing the subsequent launches. The issue of total angular momentum needs to be addressed. Subsequent launches could only cancel the angular momentum if they were somehow launched from the end of the cable with opposite angular momentum.
We can consider the total angular momentum to be a conserved scalar (keep everything moving around the Earth's axis). As a payload climbs the cable its angular momentum is increasing. Consequently the angular momentum of the cable is decreasing, so it lags behind the Earth (very very slightly). Having just read the full 15Mb document, I don't think was discussed anywhere. My guess is that the cable would lean very slightly to the west more or less permanently while you are sending up payloads. In this state the cable would also be pulling up and to the west on the mooring station, which would bleed off some angular momentum from the Earth (but never enough to measure). If you stopped sending up payloads the cable would gradually straighten. I'm not 100% sure how the converse case works (when payloads come down the cable). But one thing discussed in the thesis is how gravity applies a torque to the cable when it is not perfectly vertical. In this case an equal and opposite torque is applied to the Earth through gravity.
Very cool device, but $269 is pretty excessive considering you can get cheaper fully contained players for less. For example the 10G Neo Jukebox for $220. Hmm paradoxically you can buy the Neo Jukebox without the hard drive for an extra $10 at MTE.
I'm not saying don't buy one. The point is that you just know devices like this sliMP3 could be sold profitably for less than $50 if the volume was high enough. They are essentially the same as the Neo jukebox but with all the expensive components removed (battery, hard drive) and with an ethernet chip added. The Neo has a dinky remote control as well.
If you check out Slim Device's photos page, you can see just how 'garage' the company has been. It's pretty cool how they take you through the whole production process - almost makes me want to buy one just for that.
Not sure you were reading the same document as I was. The cable certainly does go all the way to the ground. Also, the cable described cannot really be built with existing materials because it relies on carbon nanotubes. While this material does exist, I don't believe it has ever been used as a construction material outside the laboratory.
...and has the added bonus of providing 256 grey shades of gray.
In related news, researches in Zurich have been making inroads into using flamingo enzymes to make e-paper. Currently the technique allows only for 256 grey shades of fleurescent pink, but Chief Scientist Dr Fandango promises - "It grows on you".
This is very true, but as someone else pointed out - you will gradually increase the key length as well. Also, the processor time and memory is roughly proportional to key length. They're all connected in an interesting way. So if you double the capabilities of your computer then you can double the key length without taking a performance hit. In doing so you square the time needed to brute-force crack the key.
For example, when public key cryptography was first invented (there's enough contentious history there to make the founding of Cisco look like a tea party) the cost of actually using "safe" length keys was pretty prohibitive. The founding fathers of PGP were just waiting for computers to get fast enough that this situation would be reversed and encryption would become as common as digital information. Well computers probably got fast enough in the last 80s, but encryption-for-everybody still hasn't really taken off. I guess social factors are harder to model than CPU speeds!
Er...hello...it's absolutely impossible to derive the message from the hash. The hash may contain millions of times less information than the message. The point of cryptographic hashing is that it should be impractical to fabricate a second message that will produce the same hash.
Cryptographic signing is the same principal except you encrypt the resulting hash with your private key so that it can be verified using your public key.
Slashdot Mirror
Besides the fact that most traits are caused not by one gene, but by the interaction of dozens of genes and the proteins they create, you have to consider that almost all human traits develop in accordance to someone's environment.
This has been the traditional view, that environment and parenting determine the outcome of one's upbringing. However twins' studies have been turning up some amazing evidence to the contrary.
In some cases of identical twins who were brought up in completely separate households, the twins have met again as adults and discovered incredible similarities in their lives.
An excellent overview is this Discover Channel site. In particular, check out the Jim twins.
Yeah looks like it.
ADD SOMETHING INTELLIGENT
^H^H^H^H
blib
...
Damn the lameness filter! It wouldn't let me post this comment because it had too many allcaps. Maybe this rant at the end will get it through...despite making my posting even more lame.
I couldn't agree less with your claim that preservation of wildlife is more important than human lives. One of the main reasons sub-Saharan Africa is so poor is because of problems like the tsetse fly. The article points out that they cost the region about $4.5 billion a year and these are people who can't afford that kind of loss.
If science and technology can succeed in hauling these countries into the 21st century you will see the same kinds of voluntary population control that you see in Europe, for example. Many wealthy European countries have a declining native population and it is directly related to economic wellbeing.
The suggestion that the tsetse fly, HIV, etc are helping to deal with population problems in Africa is abhorrent. We need to help solve these problems and make Africa wealthy - then the population problem will solve itself and there will be room for wildlife as well.
Nah those are with huge lasers for open-air displays. All you would need is a good laser pointer. The page you want is here where they have a bunch of cheap components like mirrors and "General scanning 124 Galvo" for a couple hundred.
Also they have a "hackers special" which includes the laser and stuff for $2700, which is almost getting down to the price-range. It looks like the galvo (motors) + mirror subsystem goes for around $1000 though - still pricey.
Nice idea, but tracking the ball movements is not going to be feasible unless you have a very fancy high-speed high-bandwidth camera and a lot of computing power to process images many times a second. The problem is mostly with the break, I should think. The balls are moving essentially at random all over the place in just a fraction of a second. The ball tracker would also have to understand the basic physics of the game, because otherwise even two balls colliding head on would present a big problem. The moving ball may appear to pass through a stationary ball for example.
But all is not lost. I don't see why you can't just track the balls on colour. In pool, each ball has a unique colour and at least some of it is always visible - even on the "stripes" balls (aka bigs or halves). Since you're not tracking movement, you can do all the image processing between shots, taking several seconds if necessary.
Finally, may I suggest, instead of an expensive projector, you could rig up a laser pointer reflected off some kind of servoed mirror. If your computer could manipulate the mirror accurately and quickly enough it could draw out the line along which you should hit. You may well be able to buy these mirror components as they are already used in laser displays for rock bands, museums, etc.
It's like the classic story of the US space-biro and the Russian lead pencils.
The US decided to use an optical mouse for the pointing device on the Hubble, but the Russian designed Hubbliski which never got off the ground due to lack of funding simply used a brown stick.
Can I just go ahead and point out the obvious here. Self-shredding email or whatever you want to call it can only work with the consent of the recipient, which goes completely against the tone of the CNN article:
Senders can destroy messages either remotely or automatically, without a recipient's consent or cooperation.
Just like the whole digital-rights management problem, eventually you have to give access to the message to your recipient and they can store a copy. If it's displayed on your screen then even the most recalcitrant software can be bypassed with a screen-shot or at absolute worst, a photograph of your monitor.
All these schemes can do is make it less convenient to store the email you receive. Even so, the receiving software could be dissasembled (DeCSS style) and you could create tools that would store the plain-text like a normal email client.
By the way, an Australian soldier was killed in Afghanistan on Saturday.
Please, do you really think America acts the world-cop because they are called to do so? Do you think they spend billions of dollars out of altruism? Wake up, you have had your own flag pulled over your eyes. The US acts out of self-interest when it comes to military intervention. The benifits are:
o Global stability (don't want any more global conflicts to flare up from seemingly inocuous local wars).
o Weapons development (there's no better field test than taking your new toys into the field and trying them out for real - war games are almost as expensive and not as effective). Weapons development is funded as a means of defending the homeland - so why do you think they are used overseas all the time?
And finally, if you think these kind of actions are just about the US, you're wrong. Europe, Australia and New Zealand are just as capable of dealing with them (yes, Australian special forces are putting there lives on the line in Afghanistan as we speak). They just don't go in as big when the US is already willing to do so. There are plenty of exceptions. The US was uninterested in the civil war in East Timor, so it's fallen to Australia to deal with it.
There's nothing new in a government monitoring such phone calls. Hasn't anyone heard of Echelon or Carnivore?
I'm not saying it's a good thing, but we can pretty much assume that it goes on all the time if you don't use strong encryption for your communications. The only thing unusual about Australia in this regard is firstly that this sort of intelligence gets mentioned publicly and secondly we Australians are very good at whipping up one-sided outrage in the national media.
In the same vein, Slashdot has a nasty tendency to go with the "Australians do it again" angle every time that nation is mentioned. "Australia" translates directly to "privacy issue" in the lexicon of Slashdot-level understanding.
I'm sure this is also a good thing for getting more haptics rendering (ie. force feedback rendering, for example) working on linux.
The challenge with haptics is getting at least a 1kHz frame-rate on force renderings. This requires soft-realtime perfomance at a minimum and is tricky on most platforms.
The writing standards in this review by Richard Menta are amongst the worst I have seen. He repeats almost every piece of information at least once (so you say it supports MP3 and WMA?) and fails to mention some pretty crucial features of any mp3 player. For example, he mentions the lithium-ion batteries "had no trouble handling the power hungry Microdives" - but how long did they actually last?!
Also, testing the VoiceNav feature with 14 songs is laughable. You basically had to know the full artist+track name anyway, so why not just memorise the 14 tracks and refer to them by number? My mp3 player has over 3000 tracks at the moment and I have no confidence that VoiceNav could handle them, despite reading this review which gave it 4 stars. And seriously, on a crowded and noisy subway train who is going to yell "Achey breaky heart" into their shirt pocket?
Not I, for more reasons than one.
How can something be both increasingly commercial and subterranean at the same time?
One pointless generalisation that we can make is that people less and less feel the need to pontificate on the direction of the 'net and are less entertained by Wired magazine "gurus" that do so.
"There is no way hydrogen is ever going to be allowed aboard an airplane," Stefener said.
I think this is an overly dismissive statement. Methanol itself is really just a hydrogen storage method. You throw in some carbon to stabilise the hydrogen and as a result, you produce carbon dioxide when the fuel is used up.
There's a lot of work going on to find non-chemical storage methods for hydrogen, such as sponges or matrices that would be explosion-proof. There's no reason to believe that this won't eventually succeed in a safer and more efficient fiel cell than methanol based ones. It will just take longer.
Their press release states:
All of these traditional methods are being enhanced by ZeoSync through collaboration with top experts from Harvard University, MIT, University of California at Berkley, Stanford University, University of Florida, University of Michigan, Florida Atlantic University, Warsaw Polytechnic, Moscow State University and Nankin and Peking Universities in China, Johannes Kepler University in Lintz Austria, and the University of Arkansas, among others.
The claims about their compression performance are clearly false - but even legitimate companies are known to exaggerate and oversell. However this list of academic collaborators is the most damning evidence of a hoax, IMHO. Having worked on quite a few projects at the interface of commercialisation and academia, I can promise you that there is no way any project can run with such a long list of partners. Maybe 2 or 3 would be beleivable.
Maybe Apple is letting them start the buzz a little early.
No I don't buy that at all. Jobs is a showman. Apple got real pissed when previous products were leaked just prior to MacWorld. It's a major embarassment - no question.
Traditional rockets tend to burn up to one quarter of their overall fuel reserves before they lift the first inches off the ground/out the silo.
What do you mean the first inches? For industrial rockets there's no way they burn a quarter of their fuel in a few inches. Maybe if you phrase it as "before they travel their own length off the pad"?
I agree generally with what you're saying. It's interesting that this discussion doesn't seem to have come up much in Edwards' report. One thing he advocates is using a floating platform like the Boeing SeaLaunch. This would allow you to move the cable out of the way of space debris on an hourly basis and away from storm systems. However the angulam momentum issue would cause an overall westward pull. The total impulse involved would be comparable to the impulse applied to the cargoes (ie. they're heavy payloads being given planetary transfer velocities), so the platform would need to be pushing east all the time in order to maintain position.
Just to summarise how I understand the angular momentum issue now: When a payload is launched its angular momentum is increased by, say, A. This is taken from the cable, causing it to lean west slightly. As it leans west it will transfer its angular momentum to the Earth via both the coupling with the ground/sea and via a correcting gravitational torque (which of course acts equally and oppositely on the cable and the Earth). The cable will then pendulate east and west, transferring angular momentum back and forth between itself and the Earth. If left in this state I suppose the oscillation would eventually dampen out from friction with the atmosphere and from induced currents in the cable as it moves through the Earth's magnetic field. This may well take millions of years though. If you then time a subsequent launch (when the cable is swinging east, say) then you can stop it in the vertical position, cancelling the oscillation. At this point the cable will have transferred 2A units of westward angular momentum to the Earth.
It may well be however that these issues are not a consideration for designers. If the induced oscillation is small enough then you could simply launch whenever you like and you would be increasing the oscillation about half the time and decreasing it the other half of the time. Overall it would be very unlikely that a problem would develop.
Yes that's what I'm saying. You take a Neo, remove the expensive bits and add an ethernet chip. I'm not saying anyone would want to do this, I'm just comparing the components you have in the different products.
Yes, finally nested 6 or 7 deep the correct and simple answer to the question. The angular momentum comes from the Earth.
As a payload climbs the cable its angular momentum is increasing. This is initially transferred to the cable which may or may not pendulate. However since the cable is pulling upwards under centripetal acceleration, it will eventually transfer its extra angular momentum to the Earth.
I don't agree however that you could cancel the effect out by timing the subsequent launches. The issue of total angular momentum needs to be addressed. Subsequent launches could only cancel the angular momentum if they were somehow launched from the end of the cable with opposite angular momentum.
We can consider the total angular momentum to be a conserved scalar (keep everything moving around the Earth's axis). As a payload climbs the cable its angular momentum is increasing. Consequently the angular momentum of the cable is decreasing, so it lags behind the Earth (very very slightly). Having just read the full 15Mb document, I don't think was discussed anywhere. My guess is that the cable would lean very slightly to the west more or less permanently while you are sending up payloads. In this state the cable would also be pulling up and to the west on the mooring station, which would bleed off some angular momentum from the Earth (but never enough to measure). If you stopped sending up payloads the cable would gradually straighten. I'm not 100% sure how the converse case works (when payloads come down the cable). But one thing discussed in the thesis is how gravity applies a torque to the cable when it is not perfectly vertical. In this case an equal and opposite torque is applied to the Earth through gravity.
Very cool device, but $269 is pretty excessive considering you can get cheaper fully contained players for less. For example the 10G Neo Jukebox for $220. Hmm paradoxically you can buy the Neo Jukebox without the hard drive for an extra $10 at MTE.
I'm not saying don't buy one. The point is that you just know devices like this sliMP3 could be sold profitably for less than $50 if the volume was high enough. They are essentially the same as the Neo jukebox but with all the expensive components removed (battery, hard drive) and with an ethernet chip added. The Neo has a dinky remote control as well.
If you check out Slim Device's photos page, you can see just how 'garage' the company has been. It's pretty cool how they take you through the whole production process - almost makes me want to buy one just for that.
Not sure you were reading the same document as I was. The cable certainly does go all the way to the ground. Also, the cable described cannot really be built with existing materials because it relies on carbon nanotubes. While this material does exist, I don't believe it has ever been used as a construction material outside the laboratory.
...and has the added bonus of providing 256 grey shades of gray.
In related news, researches in Zurich have been making inroads into using flamingo enzymes to make e-paper. Currently the technique allows only for 256 grey shades of fleurescent pink, but Chief Scientist Dr Fandango promises - "It grows on you".
This is very true, but as someone else pointed out - you will gradually increase the key length as well. Also, the processor time and memory is roughly proportional to key length. They're all connected in an interesting way. So if you double the capabilities of your computer then you can double the key length without taking a performance hit. In doing so you square the time needed to brute-force crack the key.
For example, when public key cryptography was first invented (there's enough contentious history there to make the founding of Cisco look like a tea party) the cost of actually using "safe" length keys was pretty prohibitive. The founding fathers of PGP were just waiting for computers to get fast enough that this situation would be reversed and encryption would become as common as digital information. Well computers probably got fast enough in the last 80s, but encryption-for-everybody still hasn't really taken off. I guess social factors are harder to model than CPU speeds!
Er...hello...it's absolutely impossible to derive the message from the hash. The hash may contain millions of times less information than the message. The point of cryptographic hashing is that it should be impractical to fabricate a second message that will produce the same hash.
Cryptographic signing is the same principal except you encrypt the resulting hash with your private key so that it can be verified using your public key.