The third major problem is the security hole it exposes. Once a domestic Internet kill switch has been built, why would a cyberattacker concentrate his efforts on anything else?

Given that the number of people who could use the Internet for good in a crisis situation will presumably outnumber the bad guys, it is probably best to not cut off our heavy dependence on the Web just as things are going bad. Given that a recent survey by Unisys found 61% of Americans approve of the Internet kill-switch concept, this issue will require constant vigilance.

Tell your congressmen: Back away from the switch, slowly.

4. Cable cutting

Although satellites are used for some Internet traffic, more than 99 percent of global Web traffic is dependent on deep-sea networks of fiber-optic cables that blanket the ocean floor like a nervous system. These are a major physical target in wars, especially at special choke-points in the system. And this is not simply a theoretical prediction, the underwater battles are well underway.

As much as three-fourths of the international communications between the Middle East and Europe have been carried by two undersea cables: SeaMeWe-4 and FLAG Telecom's FLAG Europe-Asia cable. On January 30, 2008, both of these cables were cut, severely disrupting Internet and telephone traffic from India to Egypt.

It is still not clear how the cables were cut, or by whom. And for that matter, it is not clear how many cables were cut: some news reports suggest that there were at least eight. Initial speculations proposed that the cuts came from a ship anchor, but a video analysis soon revealed there were no ships in that region from 12 hours before until 12 hours after the slice.

Those cables were only the beginning. A few days later, on February 1, 2008, an undersea FLAG Falcon cable in the Persian Gulf was cut 55 miles off the coast of Dubai. On February 3rd, a cable between the United Arab Emirates and Qatar was cut. On February 4th, the Khaleej Times reported that not only these cables, but also two more, a Persian Gulf cable near Iran, and a SeaMeWe4 cable off the coast of Malaysia.

These cuts led to widespread outages of the Internet, especially in Iran. Suspicions that this reflected underwater sabotage derived in no small part from the geographical pattern: almost all the cables were cut in Middle Eastern waters near Muslim nations. Who might have done it? No one knows. But it is known that the U.S. Navy has deployed undersea special operations for decades. In Operation Ivy Bells, for example, Navy divers appear to have swum from submarines to tap an undersea cable in the Kuril Islands.

Whatever the truth behind the incident, we see that if a government or organization wants badly enough to sabotage the telecommunications across a wide swath, it is possible. New deep-sea cables are urgently needed to protect the global economy because businesses worldwide are vulnerable to the targeting of "choke points" in underwater communications.

Whether by terrorists, governments or cyber-pirates, these weak points in the chain should be keeping us all up at night.

What to do about it

The Global Seed Vault in Svalbard (a small island in the Arctic) is a secure bank for the future of the world. It holds duplicate samples -- that is, spare copies -- of seeds held in gene banks worldwide. The seed vault provides insurance in the event of large-scale regional or global crises.

If a nuclear winter, say, were to wipe out all the crops on the planet, future generations could reboot the agricultural system by hoofing it out to Svalbard.

I propose that we need to have a similar backup security plan for the human knowledge that underlies the Internet.

I'm not suggesting something like the Way Back Machine, which takes snapshots of websites through time. I'm instead talking about simple instructions, burned onto physical media, for how to generate electricity, how to build a computer, how to build a router and how to reconstitute the Internet from basic principles.

The Web appears to be the single most important technology that has ever been invented. We have been the generation lucky enough to witness its inception, and we are now the ones responsible for its protection.

The opinions expressed in this commentary are solely those of David Eagleman.