Misinformation magnifies over time. This is a law of journalism.

For an example of how the law works, visit the sixth floor of the old Texas Book Depository building in Dallas. It's a tourist shrine now. You can gaze over Dealey Plaza, imagining a Lincoln Continental cruising past, presidential occupants waving. And when you do, just about every Kennedy conspiracy theory will vanish from your mind.

The road is so damn close and the view from the sixth floor so clear that Oswald could've hit President Kennedy with a baseball, if he'd had a half-decent arm. But a few reported misunderstandings about ballistics gave rise to the second gunman theory, which snowballed into a notion of Cuban/Mafia intrigue, which ultimately led us to a terrible Oliver Stone movie. Misinformation not only magnifies, it coarsens.

This week we may be seeing the beginnings of another misinformation explosion, again arising from a death in the South: Dale Earnhardt's, in Florida on Sunday during the Daytona 500. Reporting errors on the NASCAR racer's death abound, both of commission and omission.

While the latter may have been avoided through simple Internet searching, many of the former needed only a pair of eyes to get right. For three days now, the Associated Press has been reporting that Earnhardt's Chevrolet 'slammed head-on into a concrete wall at 180 mph.'

No, it didn't. We've all seen the crash, many dozens of times. Earnhardt was traveling at around 180 mph when he lost control and veered right, towards the wall. It's a physical impossibility that he maintained that velocity up to the point of impact. The car was sliding. Substantial speed was scrubbed off.

And 'head-on'? The Chev hit at an angle, probably less than 45 degrees. Look at the video, AP. From FreeRepublic.com to CNNsi, NASCAR-friendly chatrooms have been ripping this blatantly incorrect coverage since the shock of the accident wore off.

The mainstream media became more confused when reporters took as conclusive early theories on Earnhardt's injuries. At a news conference late Sunday, Dr. Steve Bohannon, head of emergency services for the 500, speculated -- with some considerable expertise, but in absence of final proof -- that Earnhardt (who experienced an unexplained series of blackouts after a crash in 1997) died from a particular type of injury where rapid deceleration causes the base of the skull to break away from the spine.

'When you have a force that will fracture the base of the skull, such as this, there's also a lot of damage to the base of the brain,' Bohannon said. 'I feel there were probably significant injuries to the base of the brain that were the cause of death.'

That was enough for most. The Indianapolis Star reported with finality on Monday that Earnhardt 'suffered head and neck injuries.' The London Guardian wrote that Earnhardt died from a seperation of skull and spine. This widespread belief provoked calls for NASCAR to force drivers to use a Head and Neck Restraining System (HANS).

In advance of autopsy reports on Monday, AP's Paul Newberry gave HANS manufacturer Ken Adams a platform to promote his device. 'The most frustrating thing is [Earnhardt] died of basilar skull fracture,' Adams told Newberry. 'That's what our device is designed to prevent. I really think he would have lived.'

It turns out, however, that Earnhardt didn't die from a basilar skull fracture (although HANS demands are today running in every mainstream U.S. newspaper). Preliminary autopsy resultsreleased late Monday revealed that Earnhardt suffered a skull fracture which ran from the front to the back of his head -- not the base. Further eroding the HANS cause, there was no spinal damage, although the crash did break Earnhardt's sternum (previously broken in a crash in 1996), eight left ribs and his left ankle.

Rib, sternum and especially leg injuries are relatively common in motor sport; a host of veteran drivers walk with what is known as 'Lola limp' after crashing British-made Lola race cars in the 1970s. But Earnhardt's skull fracture is puzzling; the autopsy reported 'blunt trauma injury' to the back of the head. This isn't usually an injury caused by the skull whipping forward, as is basilar skull injury. It's caused by something hitting the rear of Earnhardt's crash helmet hard enough to break his skull. That's an enormous hit.

One particular doctor in Florida may be worth talking to about this, although so far there is no evidence anyone has bothered to seek him out. Searching the Net archives of a few Southern and Midwest newspapers (when you want NASCAR information, it pays not to limit yourself to The New York Times) turned up an intriguing story: On Jan. 5, Earnhardt underwent surgery in Daytona Beach to remove a piece of metal from his head. He told the Detroit Free Press that he believed the eighth-of-an-inch long steel sliver had become lodged near the left temple some 24 years earlier in a workshop accident.

You would think that -- given Earnhardt died from a fractured skull, and that his injuries were concentrated on the left side of his body -- an alert journalist might care to investigate the recent operation on the left side of Earnhardt's skull. Contact the surgeon in Daytona Beach. Get expert opinion on the implications of such an operation, specifically in terms of reduced bone strength or weak points. Ask NASCAR if Earnhardt's operation was known to them before the race.

(And ask again if NASCAR refuses to talk. The organization tends toward inertia in the face of fatalities: Last year, following the deaths of drivers Adam Petty and Kenny Irwin, NASCAR reportedly failed to request copiesof their autopsies . Also, neither driver's car was subject to the sort of forensic examination by NASCAR which might be expected. While you've got NASCAR's attention, ask about any planned analysis of the Earnhardt car -- what part of it dealt the fatal blow?)

It's entirely likely Earnhardt's skull operation had nothing to do with his death -- but until questions are asked, nobody will know.

Want another law of journalism? Misinformation expands to fill the void created by lack of information.

Revised Feb. 21, 2001 -- Due to an editing error, a previous version of the story said there was an 'eight-inch long steel sliver' was lodged in Earnhardt's left temple. It should have read 'eighth-of-an-inch.'