What kind of cargo are we bringing down ? Space is empty. Bringing back dead satellites has never caught on, even when we had the shuttle.
Also, there's no reason why this capsule wouldn't be reusable. Obviously, the heat shield needs to be replaced, but the rest of the capsule should still be okay.
There's not much that you can do to improve fundamental technology to go into space, but they can still try to make things as cheap and low-weight as possible. Every kilogram that you take off the re-entry system is another kilogram of useful payload that you can take up.
Or, it could have consciousness, but if you asked it if it was conscious, it could say 'no
But then the behavior would be different. Assume we can get a simulation to a point where the behavior was exactly the same as ours. We could ask it about consciousness, intentionality, qualia even, and it would respond in similar way as you and me. Sometimes it would say things like: "hmm... I've been wondering about qualia, and I think Dennett is right", and start arguing with you. The simulation would also show the same kinds of emotions as we, get fooled by the same optical illusions, etc.. etc..
How would you determine if there really was consciousness in there ? How, in fact, would you determine that other people are really conscious ? I imagine, that if you believe p-zombies are really possible, some people may have a damaged gene for consciousness, and we would never find out. It also makes sense to believe consciousness had to evolve at some point, so therefore it must have had an effect on survival, meaning that it determines behavior.
You couldn't hope to look inside their brains and see if there's consciousness in there, if you have no idea what to look for. And learning what to look for is basically impossible, if you can't even say whether something/somebody has consciousness or not. You could be examining the brain of a person who lacks the consciousness gene.
Does that mean someone who cannot communicate are not conscious?
Obviously not, but we just wouldn't be able to tell.
The thing is, you won't find consciousness looking at the signals in the brain. The brain is composed of parts that have no consciousness themselves, and the patterns are too complicated to understand anyway. Even if you manage to see all the patterns at once, you still won't see conciousness.
The only solution is to look at the behavior. If the simulated brain can have a discussion about consciousness, it has everything you can possibly want.
Dennett has already provided some insights. The problem is that people find that it doesn't match their intuition, so they keep looking for something else. The biggest hurdle you have to take is to realize that you can't know your own consciousness. Once you get beyond that, the problem becomes a lot easier.
The time period during which we've been collecting data is insignificant compared to the age of the earth
How exactly is that relevant for the current issue ?
It's like saying that it's okay if New Orleans gets flooded, because, after all, millions of years ago, that place was under water anyway.
And yes, everybody in the field knows that H2O is a powerful greenhouse gas. We also know that CO2 is the second largest greenhouse gas, and that we've added about 35% since the industrial age. We have not a similar influence on water vapour, except that increases in sea temperature due to CO2 greenhouse effect causes higher evaporation rates, and increased atmospheric water vapour.
First of all, you'd have to pick a propulsion system, and a cruising speed (delta_v). The reaction mass required is then given by the Tsiolkovsky rocket equation (see wiki), and is equal to payload mass * exp( delta_v / exhaust_speed )
VASIMR has exhaust speed of 300 km/sec, so for a 0.1 c cruising speed, you get total reaction mass of exp(100) = 10^43 times payload mass, and a 50 year trip to a destination of 5 lightyears away.
You can reduce the mass consirably by lengthening the trip. At 0.01 c cruising speed, you "only" use 22000 times payload mass in reaction mass. Of course, the trip will take 5 centuries, and you'll fly by your destination without stopping. If you want to stop when you get there, you'll need 22000 * 22000 times the reaction mass to start with.
Note that this doesn't even answer your question about how much fuel you need for the fusion reactor to power all of this. Let's try that...
For every kg of payload, you'll need to accelerate 22000 * 22000 kg of reaction mass to 300 km/sec, which requires about 1/2 mv^2 = 10^19 joule. Assume a very good fusion reactor, converting 0.3% fuel mass into usable energy using E=mc^2, requires 10^19/0.003/c^2 = 37 tons of fusion fuel per kg of payload. Even a hypothetical antimatter power source with 100% mass conversion would require 10^19/c^2 = 111 kg of matter/antimatter per kg of payload. Of course, this fuel needs to be accelerated as well, requiring more reaction mass, and more fuel.... etc... and even these insane numbers only get you to a slow crawl of 0.01 c top speed.
A simple change of civilization does not un-invent the drill, the reactor, or the tractor
Not right away, but it doesn't take long. Burn some libraries to keep warm in the winter, turn off electricity for our computers, and it only takes a few generations to forget most things.
As far as how this applies to the topic: we currently are not anywhere near colonizing other planets. If our civilisation collapses before that point, it may never get to that point before it collapses again, and again.
It has happened before, but never with so many people, and never with such difficult energy sources.
A civilisation that depends on burning trees for energy will quickly recover. The knowledge of cutting trees is easy to remember (or re-invent), and the trees themselves grow back quickly.
We depend on oil reserves that are a few miles underground, and sometimes under an additional mile of water, which require very sophisticated technology to locate and to exploit (as the current problems with the oil spill demonstrate). This technology in turn, requires plenty of energy to get operational.
Ion rockets still needs reaction mass. Assuming 250 km/sec exhaust velocity, and 0.1 c delta-V, the total mass required is exp(30000 / 250) * Mp where Mp is mass of the payload. That's about 10^52 * Mp, and doesn't include braking when you get there.
At 0.01 c, you'll need 160,000 times payload mass of fuel to reach that speed, but then it will take several generations to reach the destination, which will introduce it's own problems. It also doesn't take into account the fuel for the energy source you need to accelerate all that mass.
No, not total depopulation. Our current civilisation is quite fragile. A simple revolution, followed by a period of total anarchy is quite feasible (it has happened multiple times before). The problem is that we are currently with many more people on earth, who can only be fed with our current advanced technology.
Most people in industrialised nations depend on easily available food in supermarkets that gets delivered with an incredibly tight just-in-time supply chain. Without food, people will panic, and destroy whatever infrastructure is left. Also, hungry people don't go to work 9-5, but stay home and try to get some food. Look what Katrina did, and multiply that to the entire USA.
Do you think people will go to work on their offshore oil platform to drill some more oil for the rest of us ? If not, gasoline will quickly run out. Without gasoline/diesel, trucks couldn't run, and no food can be transported anymore. Even the people willing to drive to work couldn't get there. The power grids shuts down, and without computers and internet, nothing gets done anymore.
It's a chain reaction to the bottom, and from that bottom it's very hard to bootstrap civilisation again, especially with 6-7 billion people that require 3 meals a day.
Slashdot Mirror
What kind of cargo are we bringing down ? Space is empty. Bringing back dead satellites has never caught on, even when we had the shuttle.
Also, there's no reason why this capsule wouldn't be reusable. Obviously, the heat shield needs to be replaced, but the rest of the capsule should still be okay.
There's not much that you can do to improve fundamental technology to go into space, but they can still try to make things as cheap and low-weight as possible. Every kilogram that you take off the re-entry system is another kilogram of useful payload that you can take up.
Or, it could have consciousness, but if you asked it if it was conscious, it could say 'no
But then the behavior would be different. Assume we can get a simulation to a point where the behavior was exactly the same as ours. We could ask it about consciousness, intentionality, qualia even, and it would respond in similar way as you and me. Sometimes it would say things like: "hmm... I've been wondering about qualia, and I think Dennett is right", and start arguing with you. The simulation would also show the same kinds of emotions as we, get fooled by the same optical illusions, etc.. etc..
How would you determine if there really was consciousness in there ? How, in fact, would you determine that other people are really conscious ? I imagine, that if you believe p-zombies are really possible, some people may have a damaged gene for consciousness, and we would never find out. It also makes sense to believe consciousness had to evolve at some point, so therefore it must have had an effect on survival, meaning that it determines behavior.
You couldn't hope to look inside their brains and see if there's consciousness in there, if you have no idea what to look for. And learning what to look for is basically impossible, if you can't even say whether something/somebody has consciousness or not. You could be examining the brain of a person who lacks the consciousness gene.
Does that mean someone who cannot communicate are not conscious?
Obviously not, but we just wouldn't be able to tell.
You could use a genetic algorithm, and get the results without understanding how it works.
The thing is, you won't find consciousness looking at the signals in the brain. The brain is composed of parts that have no consciousness themselves, and the patterns are too complicated to understand anyway. Even if you manage to see all the patterns at once, you still won't see conciousness.
The only solution is to look at the behavior. If the simulated brain can have a discussion about consciousness, it has everything you can possibly want.
Dennett has already provided some insights. The problem is that people find that it doesn't match their intuition, so they keep looking for something else. The biggest hurdle you have to take is to realize that you can't know your own consciousness. Once you get beyond that, the problem becomes a lot easier.
http://www.youtube.com/watch?v=kOxqM21qBzw
Forced delays become meaningless if the attacker has access to a large botnet
No problem, just use hydrogen instead.
What has that to do with the validity of extrapolating global temperatures from a single ice core in Greenland ? Not much, I suppose.
Here's some basic homework for anti-deniers so that they understand what they are arguing against:
http://www.foresight.org/nanodot/?p=3553
Apparently they are arguing against people who think you can extrapolate global temperature to 0.5 degree from a single ice core located in Greenland.
I fail to see how this is any different from any other climate change in the four billion year history of everything on Earth
All those other times, we weren't there to care about it. Now we are.
I thought it was the camp where attributing a cause to something that's not happening doesn't make any sense at all.
The time period during which we've been collecting data is insignificant compared to the age of the earth
How exactly is that relevant for the current issue ?
It's like saying that it's okay if New Orleans gets flooded, because, after all, millions of years ago, that place was under water anyway.
And yes, everybody in the field knows that H2O is a powerful greenhouse gas. We also know that CO2 is the second largest greenhouse gas, and that we've added about 35% since the industrial age. We have not a similar influence on water vapour, except that increases in sea temperature due to CO2 greenhouse effect causes higher evaporation rates, and increased atmospheric water vapour.
Building a dam to replace a glacier may not be a affordable option in many places of the world.
Even if that's true, that's a totally different issue, working on a completely different timescale.
There has been no global reduction in CO2 production, despite some local efforts.
http://www.esrl.noaa.gov/gmd/webdata/ccgg/trends/co2_trend_mlo.png
http://www.esrl.noaa.gov/gmd/webdata/ccgg/trends/co2_data_mlo.png
If the earth would be gradually warming over a time span of 10,000 or 100,000 years, there would be no acceleration in the recent years.
http://en.wikipedia.org/wiki/File:1000_Year_Temperature_Comparison.png
If anything, it looks like the earth was slowly cooling in the last millennium, before industrialisation started.
Strangely enough, there are also people who believe that global warming is not happening, and that the cause is not anthropogenic.
This camp is surprisingly large.
Why would the presence of glaciers 100,000 years ago cause (accelerated) warming in recent times ?
They bother, because there are still plenty of people not convinced that the earth is indeed warming.
First of all, you'd have to pick a propulsion system, and a cruising speed (delta_v). The reaction mass required is then given by the Tsiolkovsky rocket equation (see wiki), and is equal to payload mass * exp( delta_v / exhaust_speed )
VASIMR has exhaust speed of 300 km/sec, so for a 0.1 c cruising speed, you get total reaction mass of exp(100) = 10^43 times payload mass, and a 50 year trip to a destination of 5 lightyears away.
You can reduce the mass consirably by lengthening the trip. At 0.01 c cruising speed, you "only" use 22000 times payload mass in reaction mass. Of course, the trip will take 5 centuries, and you'll fly by your destination without stopping. If you want to stop when you get there, you'll need 22000 * 22000 times the reaction mass to start with.
Note that this doesn't even answer your question about how much fuel you need for the fusion reactor to power all of this. Let's try that...
For every kg of payload, you'll need to accelerate 22000 * 22000 kg of reaction mass to 300 km/sec, which requires about 1/2 mv^2 = 10^19 joule. Assume a very good fusion reactor, converting 0.3% fuel mass into usable energy using E=mc^2, requires 10^19/0.003/c^2 = 37 tons of fusion fuel per kg of payload. Even a hypothetical antimatter power source with 100% mass conversion would require 10^19/c^2 = 111 kg of matter/antimatter per kg of payload. Of course, this fuel needs to be accelerated as well, requiring more reaction mass, and more fuel.... etc... and even these insane numbers only get you to a slow crawl of 0.01 c top speed.
A simple change of civilization does not un-invent the drill, the reactor, or the tractor
Not right away, but it doesn't take long. Burn some libraries to keep warm in the winter, turn off electricity for our computers, and it only takes a few generations to forget most things.
As far as how this applies to the topic: we currently are not anywhere near colonizing other planets. If our civilisation collapses before that point, it may never get to that point before it collapses again, and again.
It has happened before, but never with so many people, and never with such difficult energy sources.
A civilisation that depends on burning trees for energy will quickly recover. The knowledge of cutting trees is easy to remember (or re-invent), and the trees themselves grow back quickly.
We depend on oil reserves that are a few miles underground, and sometimes under an additional mile of water, which require very sophisticated technology to locate and to exploit (as the current problems with the oil spill demonstrate). This technology in turn, requires plenty of energy to get operational.
Ion rockets still needs reaction mass. Assuming 250 km/sec exhaust velocity, and 0.1 c delta-V, the total mass required is exp(30000 / 250) * Mp where Mp is mass of the payload. That's about 10^52 * Mp, and doesn't include braking when you get there.
At 0.01 c, you'll need 160,000 times payload mass of fuel to reach that speed, but then it will take several generations to reach the destination, which will introduce it's own problems. It also doesn't take into account the fuel for the energy source you need to accelerate all that mass.
No, not total depopulation. Our current civilisation is quite fragile. A simple revolution, followed by a period of total anarchy is quite feasible (it has happened multiple times before). The problem is that we are currently with many more people on earth, who can only be fed with our current advanced technology.
Most people in industrialised nations depend on easily available food in supermarkets that gets delivered with an incredibly tight just-in-time supply chain. Without food, people will panic, and destroy whatever infrastructure is left. Also, hungry people don't go to work 9-5, but stay home and try to get some food. Look what Katrina did, and multiply that to the entire USA.
Do you think people will go to work on their offshore oil platform to drill some more oil for the rest of us ? If not, gasoline will quickly run out. Without gasoline/diesel, trucks couldn't run, and no food can be transported anymore. Even the people willing to drive to work couldn't get there. The power grids shuts down, and without computers and internet, nothing gets done anymore.
It's a chain reaction to the bottom, and from that bottom it's very hard to bootstrap civilisation again, especially with 6-7 billion people that require 3 meals a day.