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Thursday, February 4, 2010

Feb. 4 - Dodging the arrow of time?‏

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Dodging the arrow of time?

Posted: Tuesday, February 02, 2010 6:00 PM by Alan Boyle

Benjamin Linus (played by Michael Emerson) sets off a time-travel effect by pushing a wheel through a nexus of exotic energy in the ABC television series "Lost." Physicist Sean Carroll takes readers through a more scientifically grounded exploration of time's flow in his book, "From Eternity to Here."

The last season of "Lost" might clear up some fictional time-travel mysteries, but the true mysteries of time can be found in a new book titled "From Eternity to Here."

If the laws of physics are reversible, why can we change the future - but not the past? Why is it virtually impossible to unscramble an egg, or unstir the cream in our cup of coffee? Why does the arrow of time move in only one direction?

In the world of "Lost," the arrow of time gets tied up in knots: A mother shoots her time-traveling son before he was born ... A plane-crash survivor nearly kills a kid who grows up to enlist him as an assassin. Virtually everyone on the island gets zapped from the present to the past and the future when somebody pushes a creaky old wheel through a glowing slice of weird electromagnetic energy.

So far, however, the show hasn't run into the kinds of paradoxes that plague science-fiction tales ranging from "The Twilight Zone" to the latest "Star Trek" movie. Nobody goes back and kills Hitler to head off the Holocaust. Nobody kills his mother before he's born. As one character says, "Whatever happened, happened."

That's a refreshing perspective, says Caltech theoretical physicist Sean Carroll, the author of "From Eternity to Here."

"I'm surprised at how well time travel is treated in 'Lost,'" Carroll told me today. "It acts as a narrative illustration of what I say in the book. ... At a deeper level, they get the message: The reason why time travel affects us on a visceral level is because it touches on this idea of destiny versus choice."

It's all about the entropy

The way Carroll sees it, the mysteries of time - including the permanence of the past, as well as predestination versus free will in the future - focus on the cosmic concept known as entropy. Entropy is generally defined as the progression from order to disorder, from useful energy to useless energy equilibrium, from an ice cube to a puddle of lukewarm water.

Our universe appears to moving irrevocably from a state of low entropy (the big bang) to high entropy (the Big Chill). That means the past has less entropy than the future ... and that, in turn, means you can't go back and change things. "The way the laws of physics work, we're never going to experience anything going backward in time from our own point of view," Carroll said.

Sure, you can refreeze the water into an ice cube. Heck, it's theoretically possible to reprocess a scrambled egg, molecule by molecule, so that it looks like a raw egg again. But that requires adding more energy into the system. The total entropy of the system still goes up. It's the law - specifically, the Second Law of Thermodynamics.

Carroll's book isn't so much about the impossibility of time travel as it is about that bigger mystery of entropy. Why does the arrow of time fly in just one direction, and where did that arrow come from, anyway? Does it make sense to talk about what happened before the arrow flew?

Some physicists would say such questions can't be discussed in scientific terms. But Carroll isn't one of those physicists. After explaining in detail what we know about entropy and its relation to the arrow of time, he moves on to the more speculative side of the issue.

"Why do we ever find an egg?" Carroll asked me during our interview. "It's because it's not an isolated system in the universe. ... We should think about the universe like we think about the egg, which is that it came from something else."

Bubble universes ... again!

In the book, Carroll explains why the idea that our universe is just one isolated corner or "bubble" in a larger multiverse makes scientific sense, even though it's based totally on speculation.

The bubble-universe idea has popped up in other contexts as well - for example, to explain why our particular universe seems to work as well as it does. "It's eerily similar to what cosmologists are talking about," Carroll acknowledged. He said the bubble-universe concept is "certainly very far from established" but helps explain some features of the cosmos that scientists have long puzzled over, including the arrow of time.

Carroll suggests that the big bang could have been a cosmological blow-up that started pushing our universe from low to high entropy, and set the arrow of time on its flight path. Other bubble universes might have gone in different directions. "These universes would be created both 'forward' and 'backward' in time," Carroll said.

If we could see a high-to-low-entropy universe in action, it might look to us as if the world was running in reverse. But that's a completely theoretical "if," because every universe is completely cut off from the others.

Or are they?

"There are models out there that make predictions that haven't yet been strongly tested," Carroll said. "Pockets of bubble universes might have bumped into each other and left a spot."
Some physicists think the marks left behind by those bumps just might show up in a detailed map of cosmic microwave background radiation - perhaps even the one currently being made by the European Space Agency's Planck satellite. (However, the latest analysis of data from the Wilkinson Microwave Anisotropy Probe has not found any anomalies, as reported by Columbia mathematical physicist Peter Woit on Not Even Wrong.)

Carroll is also looking forward to seeing results from Europe's Large Hadron Collider, which is due to begin its science campaign in earnest this month. Those results may not immediately shed new light directly on the arrow-of-time question, but they will provide more grist for Carroll and his fellow theorists to chew over.
"One of the best things that could come out of the Large Hadron Collider is a better understanding of space-time," Carroll said. "Finding new particles is great, but particles are interesting because they teach us something deeper than that."

Another wrinkle in time

While we're on the subject of depth, I should mention that Carroll's 438-page book delves deeply into the details of quantum theory, thermodynamics and thought experiments such as the Boltzmann brain paradox. If you're looking for something a bit less scientifically rigorous than "From Eternity to Here" but more rigorous than "Lost," you might want to page through "In Search of Time," Canadian science writer Dan Falk's survey of the various concepts of time through the centuries.

Falk's book touches not only on the arrow(s) of time, but also on the history of timekeeping, the neuroscience of time perception and much more. Sir Martin Rees, Britain's Astronomer Royal, says it's "almost unputdownable." Because the book came out a couple of years ago, it qualifies as this month's selection for the Cosmic Log Used Book Club.

For almost eight years, the CLUB Club has been highlighting books with cosmic themes that have been around long enough to turn up at your local library or used-book shop. Send in your CLUB Club recommendation, and if it's picked up as a future monthly selection I'll send you a signed copy of my own book, "The Case for Pluto."

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How to Digitally Record/Video a UFO sighting:

Como registar digitalmente ou gravar um vídeo de um avistamento de um UFO:

Stabilize the camera on a tripod. If there is no tripod, then set it on top of a stable, flat surface. If that is not possible lean against a wall to stabilize your body and prevent the camera from filming in a shaky, unsteady manner.

Estabilize a camera com um tripé. Se não tiver um tripé, então coloque-a em cima de uma superfície estável. Se não for possível, então encoste-se a uma parede para estabilizar o corpo e evitar que a camera registe de maneira tremida e instável.

Provide visual reference points for comparison. This includes the horizon, treetops, lampposts, houses, and geographical landmarks (i.e., Horsetooth Reservoir, Mt. Adams, etc.) Provide this in the video whenever is appropriate and doesn’t detract from what your focus is, the UFO.

Forneça pontos visuais de referência para comparação. Isso inclui o horizonte, cimo das árvores, postes de iluminação, pontos de referência geográficos (como o Reservatório de Horsetooth, Mone Adams, etc) Forneça esses pontos no vídeo sempre que for apropriado e não se distraia do que é o seu foco, o UFO/a Nave.

Narrate your videotape. Provide details of the date, time, location, and direction (N,S,E,W) you are looking in. Provide your observations on the weather, including approximate temperature, windspeed, any visible cloud cover or noticeable weather anomalies or events. Narrate on the shape, size, color, movements, approximate altitude of the UFO, etc and what it appears to be doing. Also include any unusual physical, psychological or emotional sensations you might have. Narrate any visual reference points on camera so they correlate with what the viewer will see, and thereby will be better able to understand.

Faça a narração do vídeo. Forneça pormenores sobre a data, hora, local e direcção (Norte, Sul, Este, Oeste) que está a observar. Faça observações sobre as condições atmosféricas, incluindo a temperatura aproximada, velocidade do vento, quantidade de nuvens, anomalias ou acontecimentos meteorológicos evidentes. Descreva a forma, o tamanho, a cor, os movimentos, a altitude aproximada onde se encontra o UFO/nave, etc e o que aparenta estar a fazer. Inclua também quaisquer aspectos pouco habituais de sensações físicas, psicológicas ou emocionais que possa ter. Faça a narração de todos os pontos de referência visual que o espectador irá ver e que, deste modo, será capaz de compreender melhor.

Be persistent and consistent. Return to the scene to videotape and record at this same location. If you have been successful once, the UFO sightings may be occurring in this region regularly, perhaps for specific reasons unknown, and you may be successful again. You may also wish to return to the same location at a different time of day (daylight hours) for better orientation and reference. Film just a minute or two under “normal” circumstances for comparison. Write down what you remember immediately after. As soon as you are done recording the experience/event, immediately write down your impressions, memories, thoughts, emotions, etc. so it is on the record in writing. If there were other witnesses, have them independently record their own impressions, thoughts, etc. Include in this exercise any drawings, sketches, or diagrams. Make sure you date and sign your documentation.

Seja persistente e não contraditório. Volte ao local da cena e registe o mesmo local. Se foi bem sucedido uma vez, pode ser que nessa região ocorram avistamentos de UFOs/naves com regularidade, talvez por razões específicas desconhecidas, e talvez possa ser novamente bem sucedido. Pode também desejar voltar ao mesmo lugar a horas diferentes do dia (durante as horas de luz)para ter uma orientação e referência melhor. Filme apenas um ,inuto ou dois em circunstâncias “normais” para ter um termo de comparação. Escreva tudo o que viu imediatamente após o acontecimento. Logo após ter feito o registo da experiência/acontecimento, escreva imediatamente as impressões, memórias, pensamentos, emoções, etc para que fiquem registadas por escrito. Se houver outras testemunhas, peça-lhes para registar independentemente as suas próprias impressões, pensamentos, etc. Inclua quaisquer desenhos, esbolos, diagramas. Certifique-se que data e assina o seu documento/testemunho.

Always be prepared. Have a digital camera or better yet a video camera with you, charged and ready to go, at all times. Make sure you know how to use your camera (and your cell phone video/photo camera) quickly and properly. These events can occur suddenly, unexpectedly, and often quite randomly, so you will need to be prepared.

Esteja sempre preparado, Tenha sempre uma camera digital, melhor ainda, uma camera vídeo consigo, carregada e pronta a usar sempre que necessário. Certifique-se que sabe como lidar com a sua camera (ou com o seu celular/camera fotográfica) rápida e adequadamente. Esses acontecimentos podem acontecer súbita e inesperadamente e, por vezes, acidentalmente, por isso, necessita estar preparado.

Look up. Be prepared. Report. Share.

Olhe para cima, Esteja preparado, Relate, Partilhe.



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