QUESTION: Why didn't the Vikings populate America?

ANSWER: It got cold. Honest to gosh, that was a big part of it. Also they didn't have the royal backing that Columbus had, or his ambitious attitude.The Vikings were wildcatters. They were folks who sailed around the sea, pillaging here, plundering there, and sometimes setting up a farm or two. They didn't have the machinery of church and state behind them. Populating America would have been a big order for a few entrepreneurs looking for pelts and grazing land.

The Vikings were island-hoppers. They settled the Faroes, west of Norway, then went on to Iceland, and in the late 900s A.D. about 3,000 Icelanders settled Greenland, which was actually pretty green back then. Just before the turn of the millennium, a sailor got blown off course and hit North America.

Soon thereafter Leif Erikson established a colony in what is now Newfoundland. They figured they had found another island.

Their ambitions were modest, as was their enlightenment. As Daniel Boorstin notes in "The Discoverers," the Vikings didn't really discover North America. They missed the point, just like that guy at Decca records who turned down the Beatles in the early '60s. (In fairness, even Columbus missed the point: He insisted to his death that Cuba was the Asian mainland.)

One reason the Vikings didn't stick is that they didn't hit it off with the natives. In fact the Skraelings, as the Vikings called them, bombarded the Vikings with moose-bladder buzz bombs. The Norsemen packed it in after a couple of decades.

Then even Greenland became inhospitable. The climate gradually worsened, icebergs clogged the sea, and the Greenlanders died out by the early 1400s. Meanwhile, the Viking era ended in the middle of the 11th century or so, as sailors drifted home, became integrated into Western European culture, abandoned Thor and Odin for mainstream Christian beliefs and eventually bought riding lawn mowers. They stopped calling themselves Vikings and presumably threw away those helmets with the horns.

QUESTION: Why are there only four dimensions?

ANSWER: We've checked our collection of old Doctor Strange comic books - Doctor Strange is still the best name for a hero - and he was always zipping off into another dimension to fight that guy Dormamu, whose head looked like a fireball with eyes and a mouth. Factually absurd! It's high time we faced up to the fact that there are only four dimensions - at least, only four flat dimensions. Yes, flat. If you concentrate really hard you can feel the flatness. Dig it.

There may be as many as 10 or even 26 dimensions, according to some theoretical physicists. (These are physicists who exist only in theory.) The dimensions we can't see would have to be tiny, essentially irrelevant and offering no opportunity for intergalactic shortcuts for those feeling hampered by cosmic distances.

Of the four dimensions, we see three, and experience the fourth (time). Einstein realized that space and time are inseparable, that time does not have some independent reality but rather is merely a dimension by which we can describe the coordinates of an object (i.e., we can say that Michael Jordan is 10 feet off the ground at longitude 88 west and latitude 42 north at 8:30 p.m. - four coordinates).

Stephen Hawking's book, "A Brief History of Time" (universally owned but not actually read), gives a terrific summary of why our universe must be four flat dimensions. In a world with more than three spatial dimensions, gravity would more radically fluctuate according to the distance between objects (it's physics; you don't want to know more), and matter wouldn't cohere into nice stable solar systems capable of supporting life.

Moreover, living creatures probably need at least three dimensions so that blood and nutrients can circulate. A two-dimensional person couldn't consume food at one end and excrete wastes at the other, the way we three-D people do, because the gastrointestinal passageway would cut him or her into two unconnected parts.

This leaves open the possibility, though, that universes beyond our own (and admittedly it's hard to picture what "beyond" our universe means) could have one or two or 10 dimensions but not support life. Indeed, a four-dimensional universe might be rare. It's just that those are the only kind in which there are living creatures who count dimensions.

QUESTION: Why does beer give you a beer belly?

ANSWER: We thought that maybe it was the carbonation, all those accumulated bubbles swelling the gut. Nah. Wine can give you a beer belly too. So can chocolate cake. Calories are calories. Lots of beer drinkers don't get beer bellies - it just depends on your personal body composition, whether you are prone to abdominal weight gain.

The strange thing is that there is evidence that people with heavy intra-abdominal fat tend to have more heart trouble than those who bulk up elsewhere. We could swear that they also tend to smoke, wear white undershirts around the house, watch bowling tournaments on TV and never move except to wield a flyswatter, but we've got no evidence.

Washington Post Writers Group