The Boston Marathon faces a population explosion today as a record field of over 3000 qualified runners and countless unofficial crashers race the 26-mile,-385-yard course from the small town of Hopkinton to the finish line at the Prudential Center.

An event which once attracted only a few dozen harriers, in recent years the Boston Athletic Association (BAA) classic has rapidly grown in size despite the constant tightening of qualifying requirements. Now in order to qualify, a male under 40 must run a marathon in under three hourse; all others must complete the distance in under 3:30. But the lure of this famous race is such that 3016 people from all over the world have met those standards, including a record 141 women.

Among those poised for the start at noon are several world-class marathoners along with a few former winners of the event. Bill Rodgers of Melrose, who astonished onlookers in 1975 by winning the Marathon in a record 2:09.55, will join the chase as well as last year's winner, Jack Fultz, a 28-year-old Georgetown graduate from Franklin Park, Pa. (Fultz's time: 2:20.19). 1976 female champ Kim Merritt (2:47.10), who was hospitalized for exhaustion after her victory, will attempt to repeat her win without any of last year's side effects. And 1974 victor Neil Cusak will lead a group of Irish runners (Mick Molloy, Danny McDavid, Jim McNamara) in this star-studded field. Others to watch include Tom Fleming of Bloomfield, N.J., who twice has finished second, Mexico's Mario Cuevas and Toronto's Jerome Drayton (2:10.08 lifetime best). But the excitement of the Boston Marathon is in part due to the unpredictability of the finish: dark horse runners often manage to upset the favorites (Rodgers, Cusack and Fultz all fit into that category) so it's best to be prepared for the unexpected.

For Harvard a fast group of qualified runners will battle Heartbreak Hill and the strain of running without a break for three hourse. Bill Kraus, a Lowell House senior, is a sure bet to lead the Crimson contingent. He ran last year and turned in an impressive 2:39.05 to finish 79th. Kraus ran in the Silver Lake Marathon (Hopkinton to Newton, a course similar to the BAA race) in February and finished with a 2:50 and 11th-place position in near-blizzard conditions. The Akron, Ohio resident says he's looking to run the Marathon today in a time under 2:30.

Mather House will contribute two official entries--sophomore David Sullivan and Joel Arnason, a junior. Sullivan also qualified in the Silver Lake Marathon, running a 2:47.48 in his first effort. Sullivan, who has a track and cross-country background said last week there's some pressure to the race: "All these people keep telling me that they're going to come down and watch me and Jeez, what if I drop out? I tell everybody that it's my problem, not theirs. After it's all over I'm going to get drunk."

Arnason, a native of Grand Forks, N.D., said he has been running up to 75 miles a week to prepare for today. A pole-vaulter who discovered the Boston Marathon his freshman year, Arnason went back West to qualify--at the Paavo Nurmi Marathon last August (his time: 2:57). Like Kraus, Arnason wants to bring his time down about ten minutes or so, into the 2:40s.

Cross-country runners Kraus and Sullivan will be joined by teammate Bill Berkeley, formerly of Winthrop House and New Canaan, Conn., who has 2:40 ambitions for his second marathon. Berkeley finished the Silver Lake jaunt in 2:48, but his 50-to-70-mile training regimen has "been inconsistent because of school work."

Harvard's most impressive entrant is Bob Zoellick, a law school student. With several marathons in the low 2:30s to his credit, the former Swarthmore cross-country star should place high.

While the official entrants are talking confidently of sub-2:50 times, several unofficial Harvard runners are just hoping to cross the finish line on Hereford Street. Chris Bergonzi of Adams House and Armonk, N.Y. "had a horrendous time" when he ran in the Silver Lake race. Injured Harvard baseball player Steve Shevick of Evanston, Ill. has no previous racing experience but spent the last four weeks averaging ten miles a day in a crash training program. Despite his nonchalant planning, Shevick is looking forward to a 3:15-to-3:30 race, "if I finish."

Tomorrow will also provide sweet revenge for Chem 20 students as Professor Jim Wuest exchanges his lab apron for gym shorts and a "Cincinnati" T-shirt. Wuest has been running for three years and trained heavily for the past two months. After a 3:04 time in the Silver Marathon in Lowell last month, he modestly aspires to a sub-three-hour effort.