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Sat, 29 May 2004

Moore's Law to end in 600 years: Silicon Valley in panic

According to a paper by Lawrence M. Krauss and Glenn D. Starkman, there's a hard limit to the amount of computation that can be done in the universe if -- as currently observed -- it is expanding at an accelerating rate. As Physics Web explains:

the nature of the universe itself also places limits on computation because it is not possible to transmit or receive information beyond the so-called global event-horizon in an accelerating universe.

The acceleration of the universe is driven by something that has repulsive rather than attractive gravitational interactions. However, although this so-called "dark energy" is thought to account for around two-thirds of the universe, no one knows what it is made of. Possible explanations for dark energy include a "cosmological constant" or something known as quintessence.

Krauss and Starkman have determined how far an observer could travel in such a universe and still be able to transmit energy back to Earth. They then determined how much energy could be transmitted this way. To calculate the total amount of information that could be processed, they assumed that the universe has a minimum temperature, below which no energy -- and therefore no information -- can be extracted. Theory predicts that this minimum temperature exists if the universe has a cosmological constant.

The duo calculated that the total number of computer bits that could be processed in the future would be less than 1.35x10120. This means that the effective information available to any observer within the event horizon of an expanding universe will be significantly less than the total so-called Hawking-Beckenstein entropy -- the entropy that is associated with a black hole -- in the universe.

Let's not rush around screaming just yet: the universe isn't about to halt on us. To put this in human terms, Hans Moravec expounds an estimate for the computational complexity of a human brain of around 1014 ops/sec. I'm inclined to think he errs on the optimistic side by at least 3, and more likely 6-9, orders of magnitude, but it's hard to see a human brain requiring more than 1017 MIPS to simulate accurately down to the synaptic level. Elsewhere, speculative posthumanists as Robert Bradbury discuss the amount of computation you can do with the entire mass of a solar system -- it's only about 1020-25 times higher than my upper (conservative) limit for a human brain. And by the time we move on to discussions of the computational bandwidth of a Kardashev Type III civilization some really big numbers are flying around. But we're still about 1060 step-units below the upper bound derived by Krauss and Starkman. That figure of 1.35x10120 corresponds to about 1040 times the number of elementary particles in the observable universe. So we aren't going to run out of bits any time soon, at least not in human terms. But there are some other tantalizing hints that puzzle me:

"It is interesting that the numerical value in [reference 8] for the future information processing capacity of an observer in an accelerating Universe is comparable to the value claimed for the computational capacity of our entire observable Universe over its past history ..."

I'm still trying to get my head around the implications of that one. Anyone got anything to offer?

[Link] [Discuss singularity]

posted at: 19:50 | path: /space | permanent link to this entry

Where's a giant caterpilar with a hookah when you need one?

Quoth Reuters (by way of Yahoo news):

BRAZZAVILLE (Reuters) - A giant three-tiered mushroom which measures a yard across and was found in the tropical forests of the Republic of Congo has left experts in the capital Brazzaville scratching their heads.

"It's the first time we've ever seen a mushroom like this so it's difficult for us to classify. But we are going to determine what it is scientifically," Pierre Botaba, head of Congo's veterinary and zoology center, told reporters on Thursday.

The giant fungi stands 45 centimeters (18 inches) high and has three tiered caps on top of a broad stem. The bottom cap measures one meter across, the second one 60 cm and the top one is 24 cm wide, Botaba said.

The bizarre-looking mushroom was found in the village of Mvoula about 40 miles from Brazzaville and transported carefully to the capital by the local chief.

No photographs, dammit. Time to re-read Alice's Adventures in Wonderland.

[Link] [Discuss strange wildlife]

posted at: 19:15 | path: /weird | permanent link to this entry


Is SF About to Go Blind? -- Popular Science article by Greg Mone
Unwirer -- an experiment in weblog mediated collaborative fiction
Inside the MIT Media Lab -- what it's like to spend a a day wandering around the Media Lab
"Nothing like this will be built again" -- inside a nuclear reactor complex

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