Relativity on the human scale

24/09/2010

Updating Einstein’s Universe and Magic Universe

Relativity on the human scale

The most gratifying physics I’ve seen for a while comes in today’s Science magazine, from James Chin-Wen Chou and his colleagues in the Time and Frequency Division at the National Institute of Standards and Technology in Boulder, Colorado. They detect well-known effects of relativity on the rate of time passing, but now on the scale of ordinary human activities.

Standard atomic clocks employ microwaves to ensure their regularity, but Chou’s team used laser light in a pair of aluminium-27 optical clocks (invented in 2005), which gives about 100 times better accuracy. In one experiment, they used an electric field to jiggle the aluminium ion at the heart of a clock and showed that time passed more slowly in accordance Einstein’s Special Relativity theory, about the effect of motion on time. The effect of atomic motion as slow as 8 metres per second (about 30 km/h) was detectable.

Raising a clock makes it run a little faster. Credit: Chou et al., Science, 24 September 2010 – see reference.

Especially pleasing for me was another experiment, in which one clock was jacked up just 33 cm relative to the other. The clock gaining height ran faster because it was further from the Earth’s centre of gravity, and the gravitational field was slightly weaker, in accordance with General Relativity. As the change in clock rate was only about 40 parts in a billion billion (1018), its detection was a tour de force for the NIST team.

This effect of altitude on time was the key to the efforts by Martin Freeth of BBC-TV and me to make Einstein’s theory of gravity, General Relativity, comprehensible to the public, in our film “Einstein’s Universe” (1979).

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Worse than Ivan the Terrible

06/09/2010

Predictions Revisited

Worse than Ivan the Terrible

The “balance of error” for a missile boat’s captain

Prompting this post is a recent report that Russian Akula-class hunter-killer submarines are stalking British Vanguard-class submarines carrying Trident nuclear missiles. It’s the sort of thing that happened routinely during the Cold War. Thomas Harding, defence editor of the Daily Telegraph, quotes a senior Royal Navy source as saying: “The Russians have been playing games with us, the Americans and French in the North Atlantic. We have put a lot of resources into protecting Trident because we cannot afford by any stretch to let the Russians learn the acoustic profile of one of our bombers as that would compromise the deterrent.”

Bombers, by the way, is Navy slang for missile-carrying boats.

The special problems of controlling them figured in one of the predictions of possible routes to nuclear war explored in 1979 by Peter Batty and me in our BBC-TV programme “Nuclear Nightmares”.

In the accompanying book of the same title I wrote:

… the submarine as the weapon of the last resort remains an important concept and an awkward problem in command and control because, by definition, the submarine ought logically to be able to launch its missiles without receipt of explicit orders.

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What Language on Mars?

02/08/2010

Predictions Revisited

What Language Will They Speak on Mars?

The planet Mars in Chinese script. Credit: About.com: Chinese Culture, written by “js”

Chinese, on present showing. Never mind that seven men – Russian (4) European (2) and Chinese (1) – are now two months into a 520-day isolation trial in Moscow, simulating a manned mission to Mars. That’s for show. Political willpower will settle the issue.

In 1964 the rocket engineer Wernher von Braun forecast a human visit to Mars by 1984. That might well have happened had the US not cancelled its proposed Orion rocket in 1965 – the year after von Braun made his prediction. The trouble was that Orion would have had nuclear propulsion, not merely by nuclear motors, but by nuclear bombs. So it had to be abandoned in the aftermath of the nuclear test-ban treaty, much to the annoyance of Freeman J. Dyson and other enthusiasts.

Orion – the gigantic might-have-been

Here’s a diagram from my book Spaceships of the Mind (1978) which accompanied the BBC-OECA series with the same title, produced by Dick Gilling of BBC-TV. Assembled in Earth orbit, Orion would have carried about 2000 10-kiloton nuclear fission bombs, released at a rate of one a second to explode close behind a large spaceship. With a pusher plate absorbing the shocks, the spacecraft would quickly reach a speed that would take about 20 astronauts around Mars and back to Earth in just six months.

It may seem daft now but Orion was a recognition, at the very start of the Space Age, that if human beings are ever to become serious about space travel, they’ll have to think nuclear. That’s still the case, although nuclear fusion will be preferable, of course, with ignition as far from the Earth as possible.

When von Braun contributed to the New Scientist’s 1964 series on “The World in 1984” he remained mute about Orion although he glanced the nuclear option. At the time he was director of NASA’s Marshall Space Flight Center in Huntsville, Alabama, with the Apollo missions to the Moon at the top of his agenda. Here, for a start, are two early extracts from his article entitled “Exploration to the Farthest Planets”:

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Wisdom of Kilgore Trout

25/06/2010

Predictions Revisited, Updating Magic Universe, and Climate Change: News & Comments

The Wisdom of Kilgore Trout

While checking a reference for yesterday’s posting I came across an epigram concerning human behaviour that I declared, back in 1983, should rank with Einstein’s E=mc2 in physics. I quoted it in 1984 and After, but it really ought to be written on every blackboard in the world.

Who said so? None other than Kilgore Trout, the imaginary science fiction writer invented by the real-life science fiction writer, Kurt Vonnegut. In Breakfast of Champions, Vonnegut re-caps a Trout story called Plague on Wheels.

A space traveller called Kago told the Earthlings about the self-reproducing automobiles on a dying planet named Lingo-Three.

Kago did not know that human beings could be as easily felled by a single idea as by cholera or the bubonic plague. There was no immunity to cuckoo ideas on Earth.” Within a century of Kago’s arrival the Earth was dying too, littered with the shells of automobiles.

Getting an interview with Vonnegut was never easy, but when I managed it my key question was whether Kilgore Trout’s epigram expressed his own opinion. He said, Yes it did.

Before this accidental prompt, I wasn’t going to bother to comment on a paper published this week in the Proceedings of the National Academy of Sciences, no less. Anderegg et al. claim that scientists convinced about man-made global warming are cleverer and better respected, as well as much more numerous, than scientists who are unconvinced.

Now I’ll say that it’s scary but not surprising that the National Academy of Sciences should permit a division of experts into an ingroup and an outgroup, and an evaluation of them by arbitrary tests that have nothing whatever to do with the inherent substance or merit of their research. Unsurprising because it accords with Kilgore Trout’s insight into human behaviour, which has been well verified in psychological experiments.

Alec Nisbett of BBC-TV filmed one experiment called Klee-Kandinsky, executed for real with unsuspecting schoolboys, for our documentary “The Human Conspiracy” (1975).  I also summarize the experiment in Magic Universe, in the story “Altruism and aggression: looking for the origins of those human alternatives”.

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