1. Linked The 9 th Link: Achilles’ Heel The 10 th Link: Viruses and Fads Amber Cornelius Dawn Moore Mark Strausser

2. The 9 th Link: Achilles' Heel Easy to forget how dependent we are on modern technology Summer of 1996 Electricity totally down between the crest of the Rockies and the Pacific Coast In financial terms, blackout was more devastating than the Great Northeast Blackout of 1965 30 million people without power for 13 hours Today’s power grid is much more connected than the 1965 power grid

3. The 9 th Link: Achilles' Heel Power grid used to be comprised of individual islands with only weak ties to rest of the grid Blackouts caused people to panic Result of panics was that formerly islanded power systems began to link up Gave rise to the largest man-made structure on Earth, containing enough wire to reach to the moon and back

4. The 9 th Link: Achilles' Heel Huge electric grid was now so interconnected that a single disturbance could be detected thousands of miles away 1996 Blackout highlighted the vulnerability of system Connectivity made power system more robust and efficient However, errors could now cascade through entire system Connectivity caused vulnerability

5. The 9 th Link: Achilles' Heel Man-made systems are corrupted by errors and failures Vehicles Computer circuitry Natural systems have a unique ability to survive in a wide range of conditions and errors Ecosystem Between 3 and 100 million species go extinct per year, but causes little harm to overall system

6. The 9 th Link: Achilles' Heel Robustness Comes from Latin word meaning “oak” Signifies strength and longevity Symbolizes nature’s ability to maintain networks through interconnectivity Increasingly investigated topic in many fields Robustness is the ultimate goal for man- made networks and structures Copying nature’s choice of a universal network structure

7. The 9 th Link: Achilles' Heel In 1999, Defense Advanced Research Projects Agency (DARPA) called for proposals to study fault-tolerant networks “the program will focus primarily on the development of new network technologies that will allow the networks of the future to be resistant to attacks and continue to provide network services”

8. The 9 th Link: Achilles' Heel Node Failures Can easily break a network into isolated islands Such fragmentation is well-known property of networks affected by failures How long will it take to break a network if we remove random nodes? Decades of research on random networks indicates that it is not a gradual process Removing a few nodes has little impact If critical number of nodes are removed, the system abruptly breaks

9. The 9 th Link: Achilles' Heel In January 2000, the DARPA proposal motivated a series of computer experiments to test the Internet’s resilience to router failures Using an Internet map and computer simulation, started removing randomly selected nodes Expected Internet to break apart when critical number of nodes reached The Internet refused to break apart Removed as many as 80% of nodes, and remaining 20% formed a tightly interlinked cluster

10. The 9 th Link: Achilles' Heel Realized that the Internet, unlike other human made structures, showed high degree of robustness Frequent and unavoidable breakdowns of routers rarely cause significant disruptions of service Soon became clear that this robustness was not unique to the Internet Any scale-free network can tolerate removal of random nodes and not break apartscale-free network Internet World Wide Web Cell networks Social networks

11. The 9 th Link: Achilles' Heel Source of amazing robustness in scale- free networks? Hub: highly connected nodes keep networks together Failures, however, do not discriminate between nodes Affect large hubs and small nodes with same probability Small nodes more likely to be affected, as they number many, many more than large hubs

12. The 9 th Link: Achilles' Heel Scale-free networks where the degree exponent is less than or equal to three have no critical threshold Most networks of interest have a degree exponent less than three These scale-free networks will only break apart when all nodes have been removed Or for all practical purposes, never

13. The 9 th Link: Achilles' Heel Summer of 1997 National Security Agency (NSA) called for a war game to test the security of the US electronic infrastructure Hired between 25 and 50 computer specialists to execute a coordinated attack on the nation’s unclassified systems Power grid 911 systems

14. The 9 th Link: Achilles' Heel Operation Eligible Receiver Illustrated that such assaults by moderately sophisticated adversaries were plausible and potentially devastating Capable of toppling US military communication systems and other critical infrastructures completely Demonstrated frightening vulnerabilities in US economic and security systems Attacks intuitively aimed to decimate the hubs

15. The 9 th Link: Achilles' Heel The author embarked on a new set of experiments that mimicked the actions of the attackers Targeted the hubs of the network instead of randomly selecting nodes Consequences were immediately evident Removal of one hub did not break system Removal of several hubs, disruptions were clear Large chunks of nodes were falling off of the network Removing even more hubs collapsed the network entirely

16. The 9 th Link: Achilles' Heel The response of scale-free networks under attack is similar to that of random networks under failures Same collapse witnessed when: removing highly connected proteins from a yeast cell deleting highly connected nodes from food webs Crucial difference is that it only takes disabling a few hubs for the scale-free network to collapse into tiny fragments

17. The 9 th Link: Achilles' Heel DARPA refused Barabási’s paper detailing the error and attack tolerance of complex networks Nature featured it on their front cover In 2000, no one could see foresee the important role that scale-free networks would play in our understanding of attack survivability and fault tolerance The fact that the Internet was a scale-free network was only known to a few researchers Consequences were clearly unexplored

18. The 9 th Link: Achilles' Heel Robustness of scale-free network comes at cost of fragility under attack Although they are vulnerable to attack at their hubs, several of the largest hubs must be simultaneously removed to crush them Would require several hundred Internet routers to be attacked disabled at the same time It might appear that the Internet’s topology harbors strong defenses against both random breakdowns and malicious assaults Unfortunately, this is not really the case

19. The 9 th Link: Achilles' Heel 1996 blackout turned out to not be the result of an organized attack Blackout was the result of a cascading failure A cascading failure is a failure in a system of interconnected parts in which the failure of a part can trigger the failure of successive partscascading failure Local failure shifts load or responsibilities to other nodes If negligible load, can be absorbed If load is too much, node again shifts load or it fails Magnitude and reach of failure depends on the centrality and capacity of nodes removed in the first round

20. The 9 th Link: Achilles' Heel Cascading failures are not unique to power grids Internet Routers do not break, they merely form a queue and drop packets if they can’t process them fast enough End result is denial-of-service Removal of several large nodes could result in the same catastrophic disruption on the Internet as the power line failing in the 1996 blackout caused Economy 1997: International Monetary Fund puts pressure on banks, banks call loans in from companies Led to a cascade of bank and corporation failures Ecosystem Removal of a specific species can lead to a significant reorganization of the ecosystem

21. The 9 th Link: Achilles' Heel Duncan Watts, Columbia University Discovered that most cascades are not instantaneous Failure can go unnoticed for a long time before starting a landslide Cascading failures Understanding is limited They are a dynamic property of complex networks Barabási expects that there are still undiscovered laws that govern how cascading failures work Discovery of those laws would have profound implications for many fields, from the Internet to marketing

22. The 9 th Link: Achilles' Heel Error tolerance we’ve discussed is good news Network robustness allows Humans to recover from minor malfunctions and irritations Internet router errors to not really be noticed The ecosystem to continue on even as species disappear Price for this is extreme vulnerability to attacks All complex systems have their Achilles’ Heel With increased awareness and research, understanding of these issues will definitely improve over time

23. Tenth Link: Viruses and Fads Gaetan Dugas and the spread of AIDS He was known as Patient Zero He is an example of the power of HUBS Mike Collins created a cartoon about the 200 Florida ballot and he sent it to 30 of his friends The cartoon circled the globe and a business was born overnight

24. The Spread of Viruses and Fads Depends heavily on first adopters, also known as innovators Ipod Apple Newton Palm Pilots Hybrid Corn Seed Early Adopters Early Majority Late Majority Lagards

26. How do Social Ties effect Behavior 1954 Elihu Katz circulated a proposal to study the effects of social ties on behavior Fellow Columbia Alumni, was the director of Market Research at Pfizer He offered Katz and his partners 40K dollars to track the spread of Tetracycline

27. Katz, Coleman, and Menzel Study 125 Doctors 3 Doctors Discussed Medical Practices with. 3 Doctors that They sought advice About a medicine 3 Doctors that They considered To be Friends

28. Results A few of the doctors were named by a large fraction of their colleagues as playing an important role in day to day decisions. These are known as the HUBS The doctors who were named as friends were 3x’s more likely to adopt the new drug Prescriptions were followed using the local pharmacies records The early adopters and early majority had numerous social links The trend would then spread to doctors who were not as connected

29. What is a HUB Hubs are often referred to as Opinion Leaders Power Users Influencers They are individuals who communicate with more people about a certain product than the average person They are the first to notice and use the experience of the Innovators If the hubs resist a product a wall will be formed and the product will likely fail

30. Apple Newton Fails, but the a market is born! The First Mover does not always have the advantage A number of poor reviews about the Newtons hand writing recognition application Extremely poor battery life Why did Newton Fail? (Advertising is not a sufficient Argument)

32. Threshold Model We all differ in our willingness to accept innovation Diffusion Models assign a threshold to each individual, quantifying the likelihood that he or she will adopt a given innovation All products have a Spreading Rate.(From introduction to purchase) Crititical Threshold- A quantity determined by the properties of the network in which the innovation spreads If the spreading rate is lower than the critical threshold, the product will die out. If it is higher, then eventually, every user who can, will adopt the innovation Critical Threshold is part of every diffusion theory today

33. The Love Bug The Love Bug was a computer virus which spread rapidly in May 2000 It originated in the Phillipines and was one of the most destructive computer viruses to date The virus shut down financial systems in Belgium The virus also crippled operations at Parliament Eighty percent of computers belonging to the Federal government were infected The Love Bug caused over ten billion dollars in damages

34. How the Love Bug Spread An e-mail was sent to the unwitting user with a subject line that read “Love-Letter-For-You?” A user would open the e-mail and the damage began The Love Bug had an affinity for MP3 and JPEG files The Love Bug used the Outlook e-mail client to send e-mails to contacts stored in the Outlook address book The Love Bug is still around today despite having an antidote

35. A Closer Look at Viruses Romualdo Pastor-Satorras and Alessandro Vespignani concluded that the life cycle of a virus is between six and fourteen months The pair discovered that viruses were still infecting computers long after they had been “eradicated”

36. Conventional Wisdom States…. If computers are randomly connected: A virulent (highly contagious) virus which passes the threshold will reach most computers If the level of virulence is less than the threshold the number of new infections decline and the virus dies out eventually

37. Another Theory on the Spreading of Viruses Computers are not connected randomly Scale free networks appear to not have any threshold Viruses can have an indefinite life cycle Even if a virus is not highly contagious it will still spread and enjoy a long life cycle

38. Computer Viruses and AIDS Understanding how computer viruses are spread give us a good understanding how AIDS might be spread The spread of AIDS follows a similar “Power Law” logic to Scale Free networks

39. Slowing the Spread of AIDS AIDS is difficult to treat largely due to cost In places such as Africa even if the costs were reduced the lack of infrastructure would make it difficult to deliver medicines to all who needed them One method is to treat the ‘hubs’ but that requires that hubs are known members of the population

40. Slowing the Spread of AIDS The effectiveness of treating just ‘hubs’ has been questioned The fairness of only treating those who where ‘sexually connected’ has been called into question It is possible that many who needed treatment would not get it simply because they were not ‘hubs’

41. Random Events May Not Be So Random After All Random occurrences are a part of any major event Major events can be predicted with a high degree of accuracy despite random occurrences New booms can be predicted whether it is the AIDS virus or the Love Bug Virus

42. Conclusion Technology has become such a part of our lives that we take the availability of it for granted. Because our technologies are linked, a major failure in one area can cause failures in other areas in a cascading effect. A failure can be mechanical, technological, biological, intentional, or unintentional. Any mass failure of the technology we depend on will have expensive and broad reaching implications for an undefined period of time.

43. Questions?