I’m a bit of a physics geek. Not that I can do the math. But I’ve always wanted to know how the world works, and physics is the very coolest science for that. The foundation. So I decided to find three bits of news in physics to put forward as a little gift for my fellow science geeks – a bit of how the world might work for the holiday season. Continue reading All I want for Christmas is some cool new physics
I miss a lot of things about working in public libraries, but exposure to Dan Brown novels is not one of them. As such, I had no idea that Hollywood had made a movie from another of his books, Angels & Demons, but apparently they have.
Less surprising is the revelation that Brown has played fast and loose with the facts (and the writing, I fully expect); Wired UK takes a look at Brown’s antimatter-bomb-in-the-Vatican plot and points out that we’ve no need to worry about terrorists stealing the stuff from CERN:
And it’s true – scientists there really have produced antimatter. But only in submicroscopic quantities. “If you add up all the antimatter we have made in more than 30 years of antimatter physics here at CERN, and if you were very generous, you might get 10 billionths of a gram,” CERN’s Rolf Landua, told New Scientist magazine recently. “Even if that exploded on your fingertip it would be no more dangerous than lighting a match.”
It would be possible to make more, of course, but not cheap:
The cost of antimatter is, by [NASA’s] estimates $62.5 million per microgram (£41 million). However, they suggest that a dedicated antimatter production facility, with a pricetag of $3 – $10 billion, would bring the price down to just $25,000 per microgram (a mere £16 million).
But even if that much were just lying around, the storage facilities don’t exactly lend themselves to a cat-burglar raid:
Positrons can be stored in a Penning Trap, a sort of magnetic bottle. (The Air Force bought a new positron trap in December – but only for a device to examine defects in semiconductors.) However, such traps are leaky and you can’t store your positrons indefinitely. There’s also the issue of what happens when the power fails. The trap stops working and all your positrons come into contact with the container walls, which could mean a big boom. Then there’s the question of how many positrons you can store. At the moment storing a microgram of positrons would require a Penning Trap of stupendous size. A 2004 report by the US National Research Council said that much greater energy densities were needed for positrons to be useful as an explosive. The study advised against heavy investment in such a high-risk, immature technology.
So, fear not – the Vatican is safe from antimatter, at least for now. Given the size of the place, I can’t imagine why you’d think you needed anything bigger than a small nuke to take it out… but that doesn’t sound quite as exotic, I guess, and exotic puts the ‘thrill’ into ‘technothriller’. Best leave the plausibility and scientific rigour to those science fiction nerds, eh? [image by V 2]
An intriguing essay on the treatment and development of antimatter (or “contraterrene” matter) in science fiction from physicist William S. Higgins:
In 1940, Rojansky speculated that some objects in our solar system might consist of contraterrene matter. Certainly, some do not; fallen meteorites contain the same elements as terrestrial materials. If, however, a contraterrene object were orbiting the sun or passing through the solar system, it would be steadily bombarded by ordinary dust and gas. The resulting annihilation would gradually heat and erode its surface, causing volatile materials to escape and surrounding the object with a cloud of debris. In other words, it would look very much like a comet. Were some comets contraterrene?
This sparked John Campbell’s restless imagination. He imagined that space-going miners might pursue contraterrene asteroids as a rich source of energy, despite the deadly radiation risks in handling untouchable material. After author Robert Heinlein turned down the idea, Campbell offered it to veteran writer Jack Williamson. Williamson set to work.
His story, “Collision Orbit,” appeared in the July 1942 issue of Astounding Science Fiction under the pen name Will Stewart. In it, engineer Jim Drake struggles to exploit the energy of contraterrene asteroids by finding a way to manipulate them without touching them, using magnetic fields. (Read the logbook from this issue for more information.)
Ooh yes do check it out.
Well, if not impossible, then extremely difficult, expensive and time-consuming. Rocket boffins at the 44th Joint Propulsion Conference in Hartford, Connecticut believe that it would be nearly impossible to reach the stars within a human lifetime, as reported in Wired:
The major problem is that propulsion — shooting mass backwards to go forwards — requires large amounts of both time and fuel
Even the most theoretically efficient type of propulsion, an imaginary engine powered by antimatter, would still require decades to reach Alpha Centauri, according to Robert Frisbee, group leader in the Advanced Propulsion Technology Group within NASA’s Jet Propulsion Laboratory.
And then there’s the issue of fuel. It would take at least the current energy output of the entire world to send a probe to the nearest star, according to Brice N. Cassenti, an associate professor with the Department of Engineering and Science at Rensselaer Polytechnic Institute. That’s a generous figure: More likely, Cassenti says, it would be as much as 100 times that.
It’s tempting to cite Clarke’s First Law and point out the number of times in history when esteemed scientists have claimed that something is impossible until it is actually accomplished.
However what is really being said by Professors Cassenti et al is that travelling to nearby stars is merely massively expensive in terms of time and energy, to the point of being infeasible.
There are a couple of points I can think of that might be relevant to the discussion of the possibility of interstellar space travel:
1: Increased longevity – if people live longer they may change their perceptions as to what constitutes a worthwhile scientific endeavour. Waiting several decades before we receive any useful scientific information about other solar systems may be unacceptable now, but if engineered negligible senescence is achieved then that perspective might change.
2: Increased wealth – as the global economy increases in size and people (hopefully) become richer the vast amounts of investment needed to travel between the stars will become less of a barrier.
3: As Professor Cassenti says: “We just can’t extract the resources from the Earth … They just don’t exist. We would need to mine the outer planets.” Presumably after exploring and developing the solar system we would be in a better position to launch an interstellar mission – a case of learning to walk before we run.
4: If you were aiming for a one-way unmanned interstellar mission then it is likely that the ongoing miniaturisation of space technology, as exemplified by developments in micro-spacecraft described here, might help reduce the mass of any interstellar probe to the point that it becomes a cheaper prospect.
Dr Robert Frisbee describes what might be entailed by an interstellar spacecraft:
Frisbee’s design calls for a long, needle-like spaceship with each component stacked in line to keep radiation from the engines from harming sensitive equipment or people.
At the rocket end, a large superconducting magnet would direct the stream of particles created by annihilating hydrogen and antihydrogen. A regular nozzle could not be used, even if made of exotic materials, because it could not withstand exposure to the high-energy particles, Frisbee said. A heavy shield would protect the rest of the ship from the radiation produced by the reaction.
So the general conclusion seems to be that interstellar travel is hideously expensive, time-consuming and technically challenging, but hopefully just short of being impossible, as Dr Frisbee points out:
“It’s always science fiction until someone goes out and does it”
Antimatter has powered countless science fictional starships, but has yet to be used as a propulsion method in reality. Reasons are manifold: firstly, it’s very difficult and expensive to make even the tiniest amount of it; and second, we’re still not entirely sure what it is or how it works. Centauri Dreams reports on the state of antimatter research, and hopes that someday we’ll be able to use it to move between the stars.
That said, successful Space Shuttle launches aside, we’re still short of a simple and affordable route to orbit, let alone our nearest stellar neighbours. JP Aerospace reckons it has an answer to getting us at least half-way there – namely making lighter-than-air flyers to ascend to a sub-orbital space station, from which super-light orbiters could be launched. It’s a low-budget lo-fi approach, but if it works, why not?
Still hungry for space-related stuff? Carnival of Space #14 is live at Universe Today.