(Roughly) Daily

Reassurance… of a sort…

Abhay Ashtekar, a professor at the Penn State Institute for Gravitation and the Cosmos, and a team of collaborators have taken on Einstein, who suggested that not even light can escape from a black hole, and Stephen Hawking, who followed in 1970 with the assertion that information (e.g., the identity of matter that is swallowed by black holes) is permanently lost. At the time, Hawking’s assertion threatened to turn quantum mechanics– arguably the most successful physical theory ever posited by humankind–on its head, since a fundamental tenet of the theory is that information cannot be lost.

By way of explanation, Ashtekar used an analogy from Alice in Wonderland. “When the Cheshire cat disappears, his grin remains,” he said. “We used to think it was the same way with black holes. Hawking’s analysis suggested that at the end of a black hole’s life, even after it has completely evaporated away, a singularity–or a final edge to space-time–is left behind, and this singularity serves as a sink for unrecoverable information.”

But Ashtekar and his collaborators suggest that singularities do not exist in the real world. “Information only appears to be lost because we have been looking at a restricted part of the true quantum mechanical space-time,” said Varadarajan. “Once you consider quantum gravity, then space-time becomes much larger and there is room for information to reappear in the distant future on the other side of what was first thought to be the end of space-time.”

According to Ashtekar, space-time is not a continuum as physicists once believed. Instead, it is made up of individual building blocks, just as a piece of fabric, though it appears to be continuous, is made up of individual threads. “Once we realized that the notion of space-time as a continuum is only an approximation of reality, it became clear to us that singularities are merely artifacts of our insistence that space-time should be described as a continuum.”

Next up for the team, the location of socks that enter the dryer by do not emerge…

A summary of the research is here; the full report is published in the May 20 edition of Physical Review Letters.

As we recalibrate our cosmologies, we might recall that it was on this date in 1960 that the most powerful earthquake ever recorded struck Chile; epicentered in Canete (though known as the “Valdivia earthquake” as that was the most affected city); it measured 9.5 on the moment magnitude scale (the successor to the Richter scale). The resulting tsunami affected southern Chile, Hawaii, Japan, the Philippines, eastern New Zealand, south east Australia and the Aleutian Islands in Alaska. By way of contrast, the May 12 earthquake in China was of a magnitude of 7.9 on the same scale… which, readers, will recall, is logarithmic…

Valdivia after the quake

A once-level Valdiva street after the quake

Written by (Roughly) Daily

May 22, 2008 at 1:03 am

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