Which raised a question: What if nothing worked at all? What if the oil just kept coming out of the ground until it stopped naturally? How long would it take? What would be the consequences?

The quick answer is that they would be severe — though nobody is quite sure how much oil might escape because nobody, even at BP, is sure how much is down there.

“It’s huge. It’s a big oil field,” said Roger Anderson, an oil geophysicist at the Earth Institute of Columbia University. “If 20,000 barrels a day are escaping, it could stay there for years, then drop off. It could flow at a small rate for a very, very long time.”

Calls to more than a dozen experts yielded similar answers: it might be years, not months, if nothing stops the gusher, but it would not stretch into a decade. Many engineers and agencies said they would prefer not to guess.