Physics in the strangest places …

Fernanda Torres in Casa de areia
Caption: Áurea (Fernanda Torres) talks to Luiz (Enrique Diaz) in Casa de areia.

On our day off Monday, I ended up watching TV in the afternoon and stumbled upon a Brazilian movie on Starz, Casa de areia (House of Sand), that to my surprise had references to Einstein’s relativity theory in it.

The plot is minimal. The movie’s effect comes from the acting and the ironic turns in its main characters’ lives.

Áurea is a young, city-bred woman whose husband has the crackbrained idea of moving to a godforsaken plot of land on Brazil’s arid northeast (O Nordeste). Her mother, Dona Maria, accompanies them. The husband dies before the birth of Áurea’s only child, Maria, leaving the women essentially stranded in the middle of nowhere.

Áurea wants to leave in the worst way, while Dona Maria would prefer to stay. There are no men to tell her what to do, Dona Maria says. After nearly a decade stuck in O Nordeste, Áurea arranges to leave with a wandering peddler who sells salt and other sundries to the few people living in the region.

But the peddler dies en route to the women’s house. Áurea and their neighbor, a reserved man named Massu, go in search of the peddler. Along the way, Áurea tells Massu she will finish the trip on her own, following tracks in the sand. After two days, she comes across the campsite of a group of scientists photographing the solar eclipse of 1919.

A soldier accompanying the scientists explains to Áurea that the scientists are attempting to prove that the Sun’s gravity bends light by photographing the eclipse. He explains that comparing the photograph with the Sun in the way with a photograph taken later, when the Sun is not in the way, will show whether the Sun’s gravity has changed the position of the stars.

As it turns out, Albert Einstein proposed this very test when he published the general theory of relativity in 1916. His theory states that matter (the Sun, for example) warps space around it. Light and objects in that space have to follow that warpage, appearing to outside observers to bend. So a star’s position would appear to shift ever so slightly if its light grazed the “edge” of the Sun.

Einstein calculated the amount of apparent deflection, and invited astronomers to verify the calculation during a solar eclipse. Several expeditions, including one to Africa led by Sir Arthur Eddington and one in the north of Brazil, provided observational verification that Einstein’s calculations, and thus his theory, were correct. Gravity “bends” light.

The soldier, Luiz, also tells Áurea another prediction of relativity, but doesn’t quite get it right. He describes to her Einstein’s famous “twin trip” thought-experiment, demonstrating the concept of time dilation. He simplifies the explanation, leaving out the requirement that the space-traveling twin move at speeds approaching the speed of light, but the omission is probably intentional, since Áurea refers to it again toward the end of the movie.

In Luiz’ explanation, one twin stays on Earth, while the other travels through space. He tells Áurea that when the twins reunite, the space traveler will be younger than the stay-at-home twin. (She asks how he gets to space. Luiz tells her with rockets.) Now, he leaves out the critical fact that, according to the special theory of relativity, motions slows down time for the moving observer/object relative to a non-moving frame. The discrepancy depends on the speed; the closer the speed to the speed of light, the greater the difference in the twins’ ages.

So, depending on their relative speeds, the space twin could be years younger than the Earth twin once they reunite. While we don’t have direct evidence for this prediction, we do know that high speed extends the lifetimes of short-lived subatomic particles (muons, for example), exactly as special relativity predicts. We presume that what’s good for muons is good for all particles, and for us.

Back to the movie …

Luiz and Áurea fall in love, or at least they have sex, since she’s the only woman around for miles it seems. Luiz arranges with the scientists to meet Áurea in four days and take her back to civilization. This means she has barely enough time to walk home, collect her daughter, and walk back.

She never makes it. The shifting sands have buried their house in the days Áurea is gone. Áurea tries to uncover their bodies, but fails. Eventually, her daughter, Maria, reappears. But Dona Maria has died. Áurea and Maria scurry back to the campsite, but of course they are too late.

Time passes. Áurea has become middle aged, and runs a store of sorts. Maria is now in her 20s, spending most of her time being drunk and bedding any available male around. Luiz reappears. Maria bums a cigarette from him, and since he’s male, seduces him. He takes her back to her house in his Jeep, and discovers that Áurea is still alive. (He has married someone else; Áurea married Massu, so their romance is over.) Áurea convinces Luiz to take Maria back to the city.

Years pass again. The year is now 1969. Maria is now middle aged (dressed like hippie, too) and has driven the long miles to see Áurea, now an elderly woman. The moon is full, and Maria remarks that men have walked on the moon. Áurea, remembering Luiz’ fractured explanation of time dilation, asks how they got there and if they came back younger. Maria explains that, no, in fact they came back as old as they would have normally. Áurea seems disappointed, then she asks what they found on the moon. Sand, Maria says. And Áurea looks knowingly, as if such a discovery would be no surprise for a woman stuck in a desolate landscape for 60 years.

Like many foreign films, Casa de areia, moves at a languid pace, unlike the wham-bam pace of most Hollywood flicks. You have to be patient. The beauty of the film is in the acting, the cinematography and the character’s philosophical resignation to their deadend lives. As a science film, I can’t recommend it, but as an example of the craft of film making, I’d give it an 8.
[amtap amazon:asin=B00005JPGF]

Possibly Related Posts:

Leave a Reply




This site uses Akismet to reduce spam. Learn how your comment data is processed.

WP Facebook Auto Publish Powered By :