The Geological Society of London reported last month that a super-volcano is 5-10 times as likely to occur than a major meteorite impact, but could be just as disastrous.

An area the size of North America can be devastated, and pronounced deterioration of global climate would be expected for a few years following the eruption. They could result in the devastation of world agriculture, severe disruption of food supplies, and mass starvation. These effects could be sufficiently severe to threaten the fabric of civilization.

Phil and I recently examined the ten threats to civilization reported by The Guardian. To review they are:

1. Climate Change
2. Telomere Erosion
3. Viral Pandemic
4. Terrorism
5. Nuclear War
6. Meteorite Impact
7. Robot Takeover
8. Cosmic Ray Blast
9. Super-Volcano
10. Artificial Black Hole

One question that The Gaurdian left unanswered was, “which of these risks is the biggest?” Risk equals the probability that the risk will occur multiplied by the damage it would do if it did; or:

Risk = Probability x Consequences

While any of these disasters might be sufficient for the task of doing us in, some of these scenarios are more worrisome than others. I completely discount telomere erosion (manageable consequences, and I think zero probability). And the risks of climate change, viral pandemic, terrorism (which is a viral meme), and nuclear war are not likely to result in human extinction were they to occur.

We are a uniquely adaptable species, so climate change is not likely to kill us all. There’s no benefit to a virus or to terrorists to wipe out all of humanity. And the risk of global nuclear war seems to have faded as the risk of regional nuclear war has increased.

Physicists have reassured us that the artificial black hole risk is nothing to worry about – zero probability. I don’t know whether to be reassured by recent experiments or not. Obviously scientists didn’t create a black hole, but they got something totally unexpected – a perfect liquid at a trillion degrees. How certain can these guys be that there is no risk of disaster if they are capable of being completely surprised?

That said, there’s no point in arguing the level of this risk with people who know much more about the probability than I. That leaves “meteorite impact,” “robot takeover,” “cosmic ray blast,” and “super-volcano.” If we accept the Geological Society of London assessment (and I’ve got no reason to doubt it), then risk of meteorite impact is significantly less than “super vocano.” So we’re down to three.

The risk of extinction from a supernova was downgraded in 2003.

Scientists at NASA and Kansas University have determined that the supernova would need to be within 26 light years from Earth to significantly damage the ozone layer and allow cancer-causing ultraviolet radiation to saturate the Earth’s surface.

An encounter with a supernova that close only happens at a rate of about once in 670 million years.

That risk is pretty remote. So, we’re down to two great existential risks: robot/AI takeover and super-volcano. Which takes the “Big Risk” title?

Each has much to recommend it.

Ray Kurzweil tells us that the state of art in A.I. and computer science is perpetually ahead of what the public realizes. We could wake up one day in a world dominated by super-intelligent machines before we could mobilize to stop it.

Not that we could stop it if we tried. If we legislated against super-A.I. here in the U.S., it would simply push its development elsewhere. The potential payoff is too valuable to ignore, and we humans tend to push the envelope regardless of risk or benefit. If it’s possible to do, it will be done.

There is no question of “if” with a super-volcano – only when.

The Earth tends to have super-volcanic eruptions every 100,000 years. The last super-volcano to blow was 74,000 years ago. This doesn’t mean we necessarily have 26,000 years until the next huge eruption. The Yellowstone super-volcano tends to blow every 600,000 years. The last eruption was 640,000 years ago. We’re overdue.

Time to pick the “Big Risk” champion. Drum roll please…..

And the winner is…

ROBOTIC TAKEOVER!

Why? Both scenarios are pretty grim. But the human race survived the last super-volcano, and I have hope that we can survive the next one – if not on earth, perhaps in a self-sustaining off-world colony.

But the risk of robotic takeover will be with us wherever we go (see the DUNE novels and Battlestar Galactica). I agree with Kurzweil that our best bet is to be part of the leap.

The “flying car” concept contemplates a vehicle that’s as simple to operate as automobile. The average adult will not feel comfortable and safe flying an aircraft until piloting is made much simpler. In “That Flying Car Problem” I imagined a push-button aircraft that would do it all: file a flight plan, communicate with air traffic control, take off, fly, and land at your destination without interference. You’d just have to tell it where to take you. It would be a robotic air taxi.

This is the future of air travel and NASA is already taking the intermediate steps to get us there.

The folks at NASA have built something called “The Highway in the Sky.” It’s a computer system designed to let millions of people fly whenever they please, and take off and land from wherever they please, in their very own vehicles…

…here’s how it works: In a NASA animation, pilots focus on one main screen. It’s very much like a videogame. Keep the plane inside the box, away from other vehicles, and the plane’s computers automatically guide them towards their destination. They can even follow the highway down to the ground.

This is just a part of NASA’s plan. Through the Small Aircraft Transportation System (SATS) program, NASA is working on aircraft computing, advanced flight controls, Highway in the Sky displays that would overlay the windshield, and automated air traffic separation and sequencing.

Automatic separation and sequencing is extremely important. A head-up display showing a virtual highway is useful only if the highway is clear. As Jim Strickland suggested in the comments, “[an air] traffic jam would be very, very bad.”

One of the regular features at The Speculist during its inauguration was Phil’s “Seven Questions” interview. Phil’s last question was always “Why is it that in the year 2003 I still don’t have a flying car? When do you think I’ll be able to get one?”

Phil was asking the question metaphorically (when I answered I wrote about how large scale tech has been trailing small tech for the last thirty years). But really. It’s 2005 and we still don’t have flying cars. What gives? When Phil asked Aubrey de Grey, he got a more direct answer:

You don’t have [a flying car] because it’s very hard to build something that fits the bill — fast, safe, affordable. “Safe” is probably the hardest.

Of course, when I think of a “flying car” I imagine something like this:

But it doesn’t look like we’re going to get a gravity-defying roadster anytime soon. For now, this flying car will remain a “past-futures” fantasy. But why can’t we have an intermediate vehicle – a “fast, safe, and affordable” aircraft; an everyday, everyman aircraft?

Safety is a big part of this problem. A “safe” aircraft is “idiot-proof.” Most adults of average intelligence can be taught to be reasonably safe behind the wheel of a car. The flying car has to be comparably safe or it will never be adopted.

In order to be safe today, a pilot must be smart, fly constantly, have an understanding of his aircraft, a respect for the weather, and be humble about his skill. Many pilots don’t measure up to this, let alone the average “Joe.”

The answer is a push-button aircraft. You command it to “take me to Hot Springs, Arkansas” and it would file a flight plan, communicate with air traffic control, take off, fly, and land at your destination without interference from the pilot. Obviously this would require a sophisticated computer and software.

Assuming that could be accomplished in the short run, there is another obstacle to the everyday, everyman aircraft. Present-day aircraft are often more trouble than they’re worth, especially for short trips. Even people who have spent $100,000 + for a private plane often find that they don’t use them enough to justify the expense. Every flight requires a trip to an out-of-the-way airport and arrangements for ground transportation at the destination. Airports are put in out of the way places because they take up so much land.

If airplanes were made simple enough so that more people flew, and the amount of land required for a runway were reduced, then there would be more airports, making it more likely that an airport would be at or near your desired destination. Heliports don’t take up significant space – a good flat roof fits the bill. But helicopters are difficult to operate, and, even if a fully automated helicopter were developed, it would still require constant, expensive maintenance.

And the helicopter still wouldn’t be as safe as a fixed wing aircraft. There is a certain altitude range for helicopters called the “dead man zone.” If you lose your engine in this zone then there is insufficient time for the formerly powered rotor to be switched to auto-rotate mode. You drop like a rock to the ground.

Carter Aviation Technologies is developing a hybrid solution to these problems. Their “Cartercopter” allows vertical take off and landing, will fly as fast as a fixed wing aircraft (which is much faster than a helicopter), and will not be subject to the “dead man zone” problem. Why no “dead man zone?” Because as a gyroplane it is always in auto-rotate mode. If you lose power you just float down. Theoretically it would be safer than either a helicopter or an airplane in a power-off emergency landing.

There’s nothing new about gyroplanes. They’ve been around since 1923. But this form of aircraft has been neglected since the helicopter became practical. Carter Aviation saw an opportunity to innovate.

The Cartercopter’s first innovation is depleted uranium on the tips of the overhead rotor. Depleted uranium makes the tips of the rotor very heavy. While safely on the ground the overhead rotor is powered up by the engine. A gyroplane rotor is never powered in the air because it lacks a rear-stabilizing rotor like a helicopter. But once the Cartercopter’s rotor is spinning, the heavy tipped blade will maintain its spin and provide significant lift before the aircraft even begins its roll forward.

Second, the aircraft has wings like what you would expect on a fast moving jet. These wings are small and thin to hold down drag, but small wings provide limited lift. Without the rotor, the aircraft would stall at about 150 knots – the rotor makes up the difference.

At cruising altitude, the CarterCopter’s third innovation becomes available. Overhead rotor drag makes traditional gyroplanes very slow. The drag of the rotor is a cube function of the speed of the rotor. And the faster a traditional gyroplane flys, the faster the overhead rotor turns creating increasing drag. But the Cartercopter slows the rotor speed as airspeed increases. By slowing the overhead rotor from about 300 rpm to 100, the drag on the Cartercopter is significantly reduced which allows speeds comparable to fixed wing aircraft.

You might be wondering why they don’t just stop the rotor if drag would be reduced. Stopping the rotor would reduce drag, but it would be costly to engineer a stopped rotor, and the aircraft is safer with the rotor still spinning. This slowed rotation appears to be a smart compromise.

If a flying Delorean is out of the question, a fully automated Cartercopter would be a nice consolation prize.

UPDATE: Here’s a link to the video page at Discovery.com where you can see the program that inspired this post.

UPDATE II: And here’s a link to a 60 minutes print story on “flying cars” that also mentions the Cartercopter.

UPDATE III: In the comments Jim Strickland points out two additional problems with “flying cars” – noise pollution and petroleum depletion. To that I would add increased fossil fuel emissions.

Hydrogen fuel cells could address all of these problems. Hydrogen fuel cell vehicles run on electricity produced by hydrogen. It would be very quiet, would not deplete petroleum reserves, and would be clean for the environment.

Honda has done some impressive work in the last few years improving power output of fuel cell vehicles (see here and here). Whether fuel cells have been developed to the point that they could power an aircraft is another question. Probably not…yet.

InstaPundit links this morning to the Guardian’s Top Ten List of doomsday predictions. My take is that these problems are all more or less fixable, with a little ingenuity. Let’s have a look.

1: Climate Change

By the end of this century it is likely that greenhouse gases will have doubled and the average global temperature will have risen by at least 2C. This is hotter than anything the Earth has experienced in the last one and a half million years.

Well, no. According to the Klima Climate Change Center:

Changes in our climate have been occuring naturally. Ice core data have shown that the surface temperatures for the past 420,000 years have been following a steady rhythm of warming and cooling, suggesting that climate is affected by natural forcings and feedbacks.The global temperature record of the last 420,000 years shows that the amplitude of warm and cold (interglacial and ice age) events does not go beyond 8 °C.

So a 2 °C shift is well within the experience of the planet within the past 42,000 years, never mind the past 2 million. Will the 2 °C rise bring about devastation? Will it even happen?

Consider this possibility: maybe global warming is the only thing standing between us and the next ice age.

The solution to the Global Warming Doomsday scenario is twofold:

– Elimiate the politics and hysteria from the discussion

– Then define appropriate action

---

Stephen here – I was preparing a post on the same subject, but Phil beat me to the punch. My thoughts will be italicized.

There is a general concensus amoung scientists that the world is warming and that human activity is part of the problem. It is my belief that (whether fortunate or unfortunate) world petroleum production will soon peak. Petroleum prices will rise until alternatives become attractive. As those alternatives are adopted, they will be developed – made more efficient, and cheaper.

Many of these alternatives are also cleaner for the environment. I am thinking of mainly of hydrogen, but helium-3 and even cold fusion remain possibilities.

---

2: Telomere Erosion

My theory is that there is a tiny loss of telomere length from one generation to the next, mirroring the process of ageing in individuals. Over thousands of generations the telomere gets eroded down to its critical level. Once at the critical level we would expect to see outbreaks of age-related diseases occurring earlier in life and finally a population crash.

The telomere-shortening problem has been identified as one of the Seven Deadly Causes of Aging. Top minds are already at work on how to solve this problem for individuals. If Stindl’s (highly speculative)theory of species-level telomere-shortening pans out, I’m sure that whatever we come up with to address the problem for individuals will have some applicability at the species level.

If so, we’ll have yet another example of life-extension research providing “practical” (yeah, like there’s nothing “practical” about extending human life) benefits.

---

I think this theory is bogus. I’ve never heard of an upper limit for the life expectancy of a species in the fossil record. If this were a problem why do we have turtles?

But if I’m wrong and our species were due for telomere extinction in the next century, I’m convinced we would be able to engineer our way out the crisis. Provided some other catastrophe doesn’t set us back to the Stone Age, there will be a technological solution to this problem long before it became an issue.

---

3: Viral Pandemic

Within the last century we have had four major flu epidemics, along with HIV and Sars. Major pandemics sweep the world every century, and it is inevitable that at least one will occur in the future. At the moment the most serious concern is H5 avian influenza in chickens in south-east Asia.

There are some specific, practical steps we can take concerning avian strains of the flu from Asia.

Longer term, nanotechnology looks like our best pandemic defense.

---

We’re overdue for a bad flu (whether from nature or some imprudent research accident) – which is a virus. I’m also concerned that we are currently losing the antibiotics arms race against bacterial infections.

Back in 2003 Glenn Reynolds wrote briefly about “peptide nanotubes that kill bacteria by punching holes in the bacteria’s membrane… By controlling the type of peptides used to build the rings, scientists are able to design nanotubes that selectively perforate bacterial membranes without harming the cells of the host.”

This is an exciting development because bacteria would have trouble adapting to this kind of attack. As long as these nanotubes could differentiate between bacterial membranes and host membranes and penetrate bacteria, it would be lethal to bacteria.

---

4: Terrorism

Today’s society is more vulnerable to terrorism because it is easier for a malevolent group to get hold of the necessary materials, technology and expertise to make weapons of mass destruction. The most likely cause of large scale, mass-casualty terrorism right now is from a chemical or biological weapon.

Well, call me crazy, but I think what’s called for here is an outright global war on terrorism. We could even call it that — The War on Terror. The Guardian doesn’t mention whether any such solution has been considered.

Also, like with item 1, I think it’s important for us all to truly understand the problem.

---

The Guardian exposed their bias by failing to mention the War on Terror. I recommend this article to those who would like to “understand the problem.”

---

5: Nuclear War

In theory, a nuclear war could destroy the human civilisation but in practice I think the time of that danger has probably passed.

Solution: End communism in Europe. Done. Problem solved. Hey, who am I to argue with Air Marshal Lord Garden?

---

It wouldn’t take an all-out nuclear war to set our civilization back twenty years. Those who think the United States has overreacted to 9/11 would think back fondly on these carefree days were a nuke to explode within our borders.

The risk of a state actor in such an attack is low. This is one big reason why it’s so important for the U.S. to win the War on Terror. Certainly Al Qaeda wouldn’t hesitate to use a nuke against us if they could get one. Our risk is reduced if they’re busy running and dying.

---

6: Meteroite Impact

Over very long timescales, the risk of you dying as a result of a near-Earth object impact is roughly equivalent to the risk of dying in an aeroplane accident. To cause a serious setback to our civilisation, the impactor would have to be around 1.5km wide or larger.

A nasty potential problem, to be sure. While some folks are working on how best to assess and categorize the risk, others are developing actual solutions to the problem. Note that the proposed “tugboat” method is superior to the nuclear options we looked at a few years ago. Blasting an asteroid into little bits just means that we’ll be bombarded by thousands of little meteorites rather than one big one.

---

We are now entering a time when it would be possible to deflect or destroy threatening objects. Our ability to protect ourselves should improve over time barring some other catastrophe.

---

7: Robot Takeover

Robot controllers double in complexity (processing power) every year or two. They are now barely at the lower range of vertebrate complexity, but should catch up with us within a half-century. By 2050 I predict that there will be robots with humanlike mental power, with the ability to abstract and generalise.

Such robots need not become a threat, but they could. Glenn Reynolds and Scott Burgess are having some fun with the idea of “Robot Overlords,” but this is actually a fairly serious risk. Fortunately, as with Telomere shortening and asteroid impacts, there are excellent minds looking at the problem. The solution seems to be to make robots as friendly as we can while we’re still the ones making them. (Before they start making themselves.)

---

If strong A.I. is possible, then I would expect it to be achieved this century. Once achieved it would not be possible to prohibit it. The value is such that prohibition simply wouldn’t work.

What might work is a requirement that strong A.I. always be tied to a human. Symbiotic A.I. would help ensure that humanity is transformed rather than supplanted.

---

8: Cosmic Ray Blast

Once every few decades a massive star from our galaxy, the Milky Way, runs out of fuel and explodes, in what is known as a supernova. Cosmic rays (high-energy particles like gamma rays) spew out in all directions and if the Earth happens to be in the way, they can trigger an ice age.

Well, first off, I just have to ask — if it’s going to trigger an ice age, isn’t this our best hope against global warming?

Okay, seriously, we know we don’t want to be exposed to all that radiation. But what can protect us from a star exploding light years away? Here are three thoughts:

– Figure out a way to destroy, without unleashing the cosmic rays, all stars in the immediate vicinity. (Raises major ethical and logistical issues.)

– Figure out a way to move our solar system safely out of the galaxy. (Still logisitically difficult, but ethically okay.)

– Build a protective Dyson Sphere around the solar system (Cheap, safe, and easy!)

Also note that a smaller-scale Dyson sphere might be used to protect us from Asteroid collisions.

---

Supernovas are out of human control and so aren’t worth worrying about. Even an interstellar civilization would be destroyed unless it was spread over distant stars.

---

9: Super-Volcano

Approximately every 50,000 years the Earth experiences a super-volcano. More than 1,000 sq km of land can be obliterated by pyroclastic ash flows, the surrounding continent is coated in ash and sulphur gases are injected into the atmosphere, making a thin veil of sulphuric acid all around the globe and reflecting back sunlight for years to come. Daytime becomes no brighter than a moonlit night.

Based on my detailed analysis of the recent made-for-TV movie on the subject, I think our best bet is to create some kind of release valve for these systems. The pressure in a caldera system builds and builds until the gasses and magma begin to vent, leading to massive explosions. But what if we created a way for the system to vent slowly over a period of years? Obviously, this would require some engineering beyond what we currently have. (But it would be significantly easier to do than the Dyson Sphere.)

Also, slowly releasing volcanic ash into the atmosphere might be another way to offset global warming.

---

A Super-volcano is out of our control, but humanity might survive if it had a permanent off-world presence. In fact, a permanent off-world presence would protect humanity from extinction in all but the supernova, artificial black hole, and telomere erosion scenarios.

---

10: Earth Swallowed by Black Hole

Around seven years ago, when the Relativistic Heavy Ion Collider was being built at the Brookhaven National Laboratory in New York, there was a worry that a state of dense matter could be formed that had never been created before. At the time this was the largest particle accelerator to have been built, making gold ions crash head on with immense force. The risk was that this might form a stage that was sufficiently dense to be like a black hole, gathering matter from the outside.

If we’re worried about being swallowed by home-made black holes, my suggestion is that we don’t make any. If we’re worried about rogue black holes wandering in from deep space, the solution will probably lie with some kind of combination of the solutions for problems 6 and 8.

Failing that, there’s always the Space Ark.

---

The black hole scenario is uniquely scary. Most of these other risks leave the possibility of some survivors. Not this. Even an off-world presence wouldn’t necessarily save us – Mars wouldn’t be far enough to avoid disaster.

Apparently most physicists don’t think this is a real danger. I hope they’re right.

---

InstaPundit links this morning to the Guardian’s Top Ten List of doomsday predictions. My take is that these problems are all more or less fixable, with a little ingenuity. Let’s have a look.

1: Climate Change

By the end of this century it is likely that greenhouse gases will have doubled and the average global temperature will have risen by at least 2C. This is hotter than anything the Earth has experienced in the last one and a half million years.

Well, no. According to the Klima Climate Change Center:

Changes in our climate have been occuring naturally. Ice core data have shown that the surface temperatures for the past 420,000 years have been following a steady rhythm of warming and cooling, suggesting that climate is affected by natural forcings and feedbacks.The global temperature record of the last 420,000 years shows that the amplitude of warm and cold (interglacial and ice age) events does not go beyond 8 °C.

So a 2 °C shift is well within the experience of the planet within the past 42,000 years, never mind the past 2 million. Will the 2 °C rise bring about devastation? Will it even happen?

Consider this possibility: maybe global warming is the only thing standing between us and the next ice age.

The solution to the Global Warming Doomsday scenario is twofold:

– Elimiate the politics and hysteria from the discussion

– Then define appropriate action

---

Stephen here – I was preparing a post on the same subject, but Phil beat me to the punch. My thoughts will be italicized.

There is a general concensus amoung scientists that the world is warming and that human activity is part of the problem. It is my belief that (whether fortunate or unfortunate) world petroleum production will soon peak. Petroleum prices will rise until alternatives become attractive. As those alternatives are adopted, they will be developed – made more efficient, and cheaper.

Many of these alternatives are also cleaner for the environment. I am thinking of mainly of hydrogen, but helium-3 and even cold fusion remain possibilities.

---

2: Telomere Erosion

My theory is that there is a tiny loss of telomere length from one generation to the next, mirroring the process of ageing in individuals. Over thousands of generations the telomere gets eroded down to its critical level. Once at the critical level we would expect to see outbreaks of age-related diseases occurring earlier in life and finally a population crash.

The telomere-shortening problem has been identified as one of the Seven Deadly Causes of Aging. Top minds are already at work on how to solve this problem for individuals. If Stindl’s (highly speculative)theory of species-level telomere-shortening pans out, I’m sure that whatever we come up with to address the problem for individuals will have some applicability at the species level.

If so, we’ll have yet another example of life-extension research providing “practical” (yeah, like there’s nothing “practical” about extending human life) benefits.

---

I think this theory is bogus. I’ve never heard of an upper limit for the life expectancy of a species in the fossil record. If this were a problem why do we have turtles?

But if I’m wrong and our species were due for telomere extinction in the next century, I’m convinced we would be able to engineer our way out the crisis. Provided some other catastrophe doesn’t set us back to the Stone Age, there will be a technological solution to this problem long before it became an issue.

---

3: Viral Pandemic

Within the last century we have had four major flu epidemics, along with HIV and Sars. Major pandemics sweep the world every century, and it is inevitable that at least one will occur in the future. At the moment the most serious concern is H5 avian influenza in chickens in south-east Asia.

There are some specific, practical steps we can take concerning avian strains of the flu from Asia.

Longer term, nanotechnology looks like our best pandemic defense.

---

We’re overdue for a bad flu (whether from nature or some imprudent research accident) – which is a virus. I’m also concerned that we are currently losing the antibiotics arms race against bacterial infections.

Back in 2003 Glenn Reynolds wrote briefly about “peptide nanotubes that kill bacteria by punching holes in the bacteria’s membrane… By controlling the type of peptides used to build the rings, scientists are able to design nanotubes that selectively perforate bacterial membranes without harming the cells of the host.”

This is an exciting development because bacteria would have trouble adapting to this kind of attack. As long as these nanotubes could differentiate between bacterial membranes and host membranes and penetrate bacteria, it would be lethal to bacteria.

---

4: Terrorism

Today’s society is more vulnerable to terrorism because it is easier for a malevolent group to get hold of the necessary materials, technology and expertise to make weapons of mass destruction. The most likely cause of large scale, mass-casualty terrorism right now is from a chemical or biological weapon.

Well, call me crazy, but I think what’s called for here is an outright global war on terrorism. We could even call it that — The War on Terror. The Guardian doesn’t mention whether any such solution has been considered.

Also, like with item 1, I think it’s important for us all to truly understand the problem.

---

The Guardian exposed their bias by failing to mention the War on Terror. I recommend this article to those who would like to “understand the problem.”

---

5: Nuclear War

In theory, a nuclear war could destroy the human civilisation but in practice I think the time of that danger has probably passed.

Solution: End communism in Europe. Done. Problem solved. Hey, who am I to argue with Air Marshal Lord Garden?

---

It wouldn’t take an all-out nuclear war to set our civilization back twenty years. Those who think the United States has overreacted to 9/11 would think back fondly on these carefree days were a nuke to explode within our borders.

The risk of a state actor in such an attack is low. This is one big reason why it’s so important for the U.S. to win the War on Terror. Certainly Al Qaeda wouldn’t hesitate to use a nuke against us if they could get one. Our risk is reduced if they’re busy running and dying.

---

6: Meteroite Impact

Over very long timescales, the risk of you dying as a result of a near-Earth object impact is roughly equivalent to the risk of dying in an aeroplane accident. To cause a serious setback to our civilisation, the impactor would have to be around 1.5km wide or larger.

A nasty potential problem, to be sure. While some folks are working on how best to assess and categorize the risk, others are developing actual solutions to the problem. Note that the proposed “tugboat” method is superior to the nuclear options we looked at a few years ago. Blasting an asteroid into little bits just means that we’ll be bombarded by thousands of little meteorites rather than one big one.

---

We are now entering a time when it would be possible to deflect or destroy threatening objects. Our ability to protect ourselves should improve over time barring some other catastrophe.

---

7: Robot Takeover

Robot controllers double in complexity (processing power) every year or two. They are now barely at the lower range of vertebrate complexity, but should catch up with us within a half-century. By 2050 I predict that there will be robots with humanlike mental power, with the ability to abstract and generalise.

Such robots need not become a threat, but they could. Glenn Reynolds and Scott Burgess are having some fun with the idea of “Robot Overlords,” but this is actually a fairly serious risk. Fortunately, as with Telomere shortening and asteroid impacts, there are excellent minds looking at the problem. The solution seems to be to make robots as friendly as we can while we’re still the ones making them. (Before they start making themselves.)

---

If strong A.I. is possible, then I would expect it to be achieved this century. Once achieved it would not be possible to prohibit it. The value is such that prohibition simply wouldn’t work.

What might work is a requirement that strong A.I. always be tied to a human. Symbiotic A.I. would help ensure that humanity is transformed rather than supplanted.

---

8: Cosmic Ray Blast

Once every few decades a massive star from our galaxy, the Milky Way, runs out of fuel and explodes, in what is known as a supernova. Cosmic rays (high-energy particles like gamma rays) spew out in all directions and if the Earth happens to be in the way, they can trigger an ice age.

Well, first off, I just have to ask — if it’s going to trigger an ice age, isn’t this our best hope against global warming?

Okay, seriously, we know we don’t want to be exposed to all that radiation. But what can protect us from a star exploding light years away? Here are three thoughts:

– Figure out a way to destroy, without unleashing the cosmic rays, all stars in the immediate vicinity. (Raises major ethical and logistical issues.)

– Figure out a way to move our solar system safely out of the galaxy. (Still logisitically difficult, but ethically okay.)

– Build a protective Dyson Sphere around the solar system (Cheap, safe, and easy!)

Also note that a smaller-scale Dyson sphere might be used to protect us from Asteroid collisions.

---

Supernovas are out of human control and so aren’t worth worrying about. Even an interstellar civilization would be destroyed unless it was spread over distant stars.

---

9: Super-Volcano

Approximately every 50,000 years the Earth experiences a super-volcano. More than 1,000 sq km of land can be obliterated by pyroclastic ash flows, the surrounding continent is coated in ash and sulphur gases are injected into the atmosphere, making a thin veil of sulphuric acid all around the globe and reflecting back sunlight for years to come. Daytime becomes no brighter than a moonlit night.

Based on my detailed analysis of the recent made-for-TV movie on the subject, I think our best bet is to create some kind of release valve for these systems. The pressure in a caldera system builds and builds until the gasses and magma begin to vent, leading to massive explosions. But what if we created a way for the system to vent slowly over a period of years? Obviously, this would require some engineering beyond what we currently have. (But it would be significantly easier to do than the Dyson Sphere.)

Also, slowly releasing volcanic ash into the atmosphere might be another way to offset global warming.

---

A Super-volcano is out of our control, but humanity might survive if it had a permanent off-world presence. In fact, a permanent off-world presence would protect humanity from extinction in all but the supernova, artificial black hole, and telomere erosion scenarios.

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10: Earth Swallowed by Black Hole

Around seven years ago, when the Relativistic Heavy Ion Collider was being built at the Brookhaven National Laboratory in New York, there was a worry that a state of dense matter could be formed that had never been created before. At the time this was the largest particle accelerator to have been built, making gold ions crash head on with immense force. The risk was that this might form a stage that was sufficiently dense to be like a black hole, gathering matter from the outside.

If we’re worried about being swallowed by home-made black holes, my suggestion is that we don’t make any. If we’re worried about rogue black holes wandering in from deep space, the solution will probably lie with some kind of combination of the solutions for problems 6 and 8.

Failing that, there’s always the Space Ark.

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The black hole scenario is uniquely scary. Most of these other risks leave the possibility of some survivors. Not this. Even an off-world presence wouldn’t necessarily save us – Mars wouldn’t be far enough to avoid disaster.

Apparently most physicists don’t think this is a real danger. I hope they’re right.

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