Jewish World Review June 8, 2004 / 19 Sivan, 5764
How search engines work; time travel; more
Q: How do Internet search engines like Google find stuff? Eric Fordley
A: Eric, did you know Google's original name was Backrub? It's true.
Backrub is a reference to analyzing certain Web links. Now, I love a nice backrub, and Google is a funky word. (It's a reference to "googol," a name for a very large number.)
But I wonder if the company on the brink of making a $2.7 billion initial public stock offering would've had the same success with the image of a cozy little massage.
Chris Sherman, an industry expert and the editor of SearchDay, the daily newsletter of SearchEngineWatch.com, walked us through the search engine process.
The key thing to understand is that search engines don't actually search the Web. They search their own databases. That's how they can pop back up with a response so fast.
Every few weeks, search engines do what's called a "crawl." This is when computer "robots" surf the Web, downloading as many pages as fast as they can - millions of pages per hour. Google says it has downloaded roughly 5 billion Web pages. Smaller crawls are done all the time to update this cache.
All of these pages are copied and stored on tens of thousands of servers. (Some estimate that Google's servers could comprise the world's largest supercomputer.) Then all these pages are indexed to show what they contain. So when we do a search, the engine doesn't have to look all around the Web. It just has to flip through this index, which is a sort of map of the Web.
Search engines do something else when you punch in a search. They ask, "What is this person really looking for?" There are often thousands - perhaps millions - of responses to a search engine query. A search engine wants to show you the best ones first. But how does it prioritize?
A big search engine like Google includes perhaps 100 factors to decide this. A few are:
How often the search terms appear in a page.
Whether search terms are in the title of the page.
How popular a page is, based on the number of other pages that link to it.
That's why if you type in the words James Bond (with no quote marks) and hit search, you'll see an official James Bond search engine on the top of the list. But millions of pages include those two words. What's at the bottom of the list? I looked. One page was an ad for a guy selling a rhino. Google assumed - correctly - that I wasn't looking for that.
What can't search engines do? Lots. Only a tiny fraction of the world's knowledge is online. We need discussion and books more than ever.
And no matter how good a search engine is, it still can't give a decent backrub.
Q: Is time travel possible? Patricia Nims
A: Patricia, the droll comedian Steven Wright tells this joke:
"I went into a restaurant and the sign said BREAKFAST ANYTIME. So I ordered French toast during the Renaissance."
And that's how many of us think of time travel: You hop in a machine and stroll out into the Stone Age or the American Revolution or the 1950s. (Where your then-teenage mom gets a crush on you, as happened in "Back to the Future.")
That ain't gonna happen.
Although time travel is still vastly unexplored and holds many possibilities, the great thinkers agree that it will never be like we see it in the movies.
It's not science fiction, but astrophysics.
So I turned to the good people at Princeton University's astrophysics department. One of the world's great thinkers on this subject, professor Richard Gott, and his colleague, Michael Strauss, were nice enough to help.
Time travel is possible, at least to an extent.
Much of it is based on one principle: An object traveling at a very high speed "ages more slowly" than a stationary object. This means that, if you were to travel into outer space and return moving close to light speed, you would age slower than the people on Earth.
Let's say you had a twin who was, obviously, exactly the same age as you. If you took this super-fast journey, you might return to Earth to find she was now a month older than you. (Or 10 years older than you, depending on the length and speed of your journey.) All kinds of other things had happened while you were gone. Thereby with your high-speed journey you would have "traveled into the future."
Some physicists believe we might be able to capitalize on this principle to travel quite far into the Earth's future. You couldn't travel back, though. Once you made a trip to the future via ultrahigh speeds, you couldn't undo it.
Of course, we're nowhere near building a spaceship that can travel at close to the speed of light. But this principle has been shown in very limited experiments and has been gradually developed since Einstein revolutionized physics with his "special theory of relativity" showing how time changes with motion.
Time travel to the past presents other problems. Many astrophysicists believe we will never be able to zip back three days and return those videos before they're overdue, or prevent the recording of "The Macarena."
There are many arguments against the feasibility of time travel to the past. One of the most famous is "the grandfather paradox": If you traveled into the past and killed your own grandfather before your father was born, what would happen to you? Wouldn't any change made in the past (including a visit by a time traveler, itself) be problematic, because it would affect events that had already happened?
But some astrophysicists have refuted the grandfather paradox and used Einstein's theories to show travel to the past is possible. Perhaps time travelers could visit the past, but not affect it. Perhaps they were always part of the past, but we didn't realize it. Some even suggest there could be "parallel universes" so that time travelers could affect the past.
At the very least, astrophysicists say time travel to the past would be limited in one major way: One could not travel back in time to before when the time machine was invented. If a time machine were invented in 3000, you would not be able to travel back to 2004. It appears the trip to ancient Greece is off.
Many time travel obstacles might someday be overcome using natural phenomena like black holes, "worm holes" or "cosmic strings." Or time travel might someday be achieved with new applications of Einstein's theories and exploration of sciences like quantum gravity - how gravity behaves on microscopic scales.
It all sounds fantastic now. But who knows? Skeptics scoffed at the airplane, telephone and computer, too.
You can read more from professor Gott in his fascinating book "Time Travel in Einstein's Universe."
The PBS program "Nova" has a terrific Web site on time travel, where we also found material for this column, at www.pbs.org/wgbh/nova/time/. And here's a page with links to other sites on time travel: http://science.howstuffworks.com/time-travel7.htm. (The hyphen is part of the Web address.)
On brain-freezing delights:
1. What frozen cocktail got its name from a village near Santiago, Cuba?
2. George Washington ran up a $200 bill for what one summer? a) Iced tea b)
Ice cream c) Lemonade d) King Cobra
3. What frozen concoction did Jimmy Buffett immortalize?
4. Cola, vanilla ice cream and chocolate syrup are referred to as what
5. What Ben & Jerry's flavor takes its name from a legendary rock star?
2. b) Ice cream
4. Brown cow
5. Cherry Garcia
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