physics

MAINWAY

MAINWAY is a physics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand MAINWAY rather than just read about it. In short: MAINWAY is a database maintained by the United States' National Security Agency (NSA) containing metadata for hundreds of billions of telephone calls made through the largest telephone carriers in the United States, including AT&T, Verizon, and T-Mobile. The existence of this database and the NSA program that compiled it was unknown to the general public until USA Today broke the story on May 10, 2006.

Key takeaways

MAINWAY belongs to physics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect MAINWAY to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of MAINWAY from memory before moving on to harder problems.

Reference excerpt

MAINWAY is a database maintained by the United States' National Security Agency (NSA) containing metadata for hundreds of billions of telephone calls made through the largest telephone carriers in the United States, including AT&T, Verizon, and T-Mobile.

The existence of this database and the NSA program that compiled it was unknown to the general public until USA Today broke the story on May 10, 2006. It is estimated that the database contains over 1.9 trillion call-detail records. The records include detailed call information (caller, receiver, date/time of call, length of call, etc.) for use in traffic analysis and social network analysis, but do not include audio information or transcripts of the content of the phone calls. According to former NSA director Michael Hayden, the NSA sought to deploy MAINWAY prior to 9/11 in response to the Millennium Plot but did not do so because it did not comply with US law. Hayden wrote: "The answer from [the Justice Department] was clear: ' ... you can't do this.'" As of June 2013, the database stores metadata for at least five years. According to Pulitzer Prize winning journalist James Risen, MAINWAY was the most important of the four components that comprised the ThinThread program. The database's existence has prompted fierce objections. It is often viewed as an illegal warrantless search and violation of the pen register provisions of the Foreign Intelligence Surveillance Act and (in some cases) the Fourth Amendment of the United States Constitution. The George W. Bush administration neither confirmed nor denied the existence of the domestic call record database. This contrasts with a related NSA controversy concerning warrantless surveillance of selected telephone calls; in that case they did confirm the existence of the program of debated legality. That program's code name was Stellar Wind. Similar programs exist or are planned in other countries, including Sweden (Titan traffic database) and Great Britain (Interception Modernisation Programme). The MAINWAY equivalent for Internet traffic is MARINA.

Content According to an anonymous source, the database is "the largest database ever assembled in the world," and contains call-detail records (CDRs) for all phone calls, domestic and international. A call-detail record consists of the phone numbers of the callers and recipients along with time, position and duration of the call. While the database does not contain specific names or addresses, that information is widely available from non-classified sources. According to the research group TeleGeography, AT&T (including the former SBC), Verizon, and BellSouth connected nearly 500 billion telephone calls in 2005 and nearly two trillion calls since late 2001. It is reported that all four companies were paid to provide the information to the NSA.

Usage Although such a database of phone records would not be useful as a tool in itself for national security, it could be used as an element of broader national security analytical efforts and data mining. These efforts could involve analysts using the data to connect phone numbers with names and links to persons of interest. Such efforts have been the focus of the NSA's recent attempts to acquire key technologies from high tech firms in Silicon Valley and elsewhere. Link analysis software, such as Link Explorer or the Analyst's Notebook, is used by law enforcement to organize and view links that are demonstrated through such information as telephone and financial records, which are imported into the program from other sources. Neural network software is used to detect patterns, classify and cluster data as well as forecast future events. Using relational mathematics, it is possible to find out if someone changes their telephone number by analyzing and comparing calling patterns. ThinThread, a system designed largely by William Binney, which pre-dated this database, but was discarded for the Trailblazer Project, introduced some of the technology which is used to analyze the data. Michael Hayden, former director of the NSA, admitted as much in an interview, saying: "But we judged fundamentally that as good as [ThinThread] was, and believe me, we pulled a whole bunch of elements out of it and used it for our final solution for these problems, as good as it was, it couldn't scale sufficiently to the volume of modern communications." Where ThinThread encrypted privacy data, however, no such measures have been reported with respect to the current system.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with MAINWAY

Start with the simplest possible case. Write down what MAINWAY claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to MAINWAY before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about MAINWAY ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of MAINWAY

In research: MAINWAY appears in physics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses MAINWAY in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: MAINWAY is common in secondary-school and first-year university syllabi. It links to neighbouring topics Counterterrorism in the United States, George W. Bush administration controversies, Government databases in the United States, so understanding it makes those chapters shorter.
In everyday life: Look for MAINWAY outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study MAINWAY in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what MAINWAY means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain MAINWAY out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is MAINWAY in simple terms?

Why does MAINWAY matter?

Because it connects several physics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study MAINWAY?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on MAINWAY.